Imaginal Disc Abnormalities in Lethal Mutants of Drosophila

PubMed Central

Shearn, Allen; Rice, Thomas; Garen, Alan; Gehring, Walter

1971-01-01

Late lethal mutants of Drosophila melanogaster, dying after the larval stage of development, were isolated. The homozygous mutant larvae were examined for abnormal imaginal disc morphology, and the discs were injected into normal larval hosts to test their capacities to differentiate into adult structures. In about half of the mutants analyzed, disc abnormalities were found. Included among the abnormalities were missing discs, small discs incapable of differentiating, morphologically normal discs with limited capacities for differentiation, and discs with homeotic transformations. In some mutants all discs were affected, and in others only certain discs. The most extreme abnormal phenotype is a class of “discless” mutants. The viability of these mutant larvae indicates that the discs are essential only for the development of an adult and not of a larva. The late lethals are therefore a major source of mutants for studying the genetic control of disc formation. Images PMID:5002822

Effect of corticosterone on larval growth, antipredator behaviour and metamorphosis of Hylarana indica.

PubMed

Kulkarni, P S; Gramapurohit, N P

2017-09-15

Corticosterone (CORT), a principal glucocorticoid in amphibians, is known to regulate diverse physiological processes including growth and metamorphosis of anuran tadpoles. Environmental stressors activate the neuroendocrine stress axis (hypothalamus-pituitary-interrenal axis, HPI) leading to an acute increase in CORT, which in turn, helps in coping with particular stress. However, chronic increase in CORT can negatively affect other physiological processes such as growth and metamorphosis. Herein, we studied the effect of exogenous CORT on larval growth, antipredator behaviour and metamorphic traits of Hylarana indica. Embryonic exposure to 5 or 20μg/L CORT did not affect their development, hatching duration as well as larval growth and metamorphosis. Exposure of tadpoles to 10 or 20μg/L CORT throughout larval development caused slower growth and development leading to increased body mass at stage 37. However, body and tail morphology of tadpoles was not affected. Interestingly, larval exposure to 5, 10 or 20μg/L CORT enhanced their antipredator response against kairomones in a concentration-dependent manner. Further, larval exposure to increasing concentrations of CORT resulted in the emergence of heavier froglets at 10 and 20μg/L while, delaying metamorphosis at all concentrations. Interestingly, the heavier froglets had shorter hindlimbs and consequently shorter jump distances. Tadpoles exposed to 20μg/L CORT during early, mid or late larval stages grew and developed slowly but tadpole morphology was not altered. Interestingly, exposure during early or mid-larval stages resulted in an enhanced antipredator response. These individuals metamorphosed later but at higher body mass while SVL was unaffected. Copyright © 2016 Elsevier Inc. All rights reserved.

Staggered larval time-to-hatch and insecticide resistance in the major malaria vector Anopheles gambiae S form.

PubMed

Kaiser, Maria L; Koekemoer, Lizette L; Coetzee, Maureen; Hunt, Richard H; Brooke, Basil D

2010-12-14

Anopheles gambiae is a major vector of malaria in the West African region. Resistance to multiple insecticides has been recorded in An. gambiae S form in the Ahafo region of Ghana. A laboratory population (GAH) established using wild material from this locality has enabled a mechanistic characterization of each resistance phenotype as well as an analysis of another adaptive characteristic - staggered larval time-to-hatch. Individual egg batches obtained from wild caught females collected from Ghana and the Republic of the Congo were monitored for staggered larval time-to-hatch. In addition, early and late larval time-to-hatch sub-colonies were selected from GAH. These selected sub-colonies were cross-mated and their hybrid progeny were subsequently intercrossed and back-crossed to the parental strains. The insecticide susceptibilities of the GAH base colony and the time-to-hatch selected sub-colonies were quantified for four insecticide classes using insecticide bioassays. Resistance phenotypes were mechanistically characterized using insecticide-synergist bioassays and diagnostic molecular assays for known reduced target-site sensitivity mutations. Anopheles gambiae GAH showed varying levels of resistance to all insecticide classes. Metabolic detoxification and reduced target-site sensitivity mechanisms were implicated. Most wild-caught families showed staggered larval time-to-hatch. However, some families were either exclusively early hatching or late hatching. Most GAH larvae hatched early but many egg batches contained a proportion of late hatching larvae. Crosses between the time-to-hatch selected sub-colonies yielded ambiguous results that did not fit any hypothetical models based on single-locus Mendelian inheritance. There was significant variation in the expression of insecticide resistance between the time-to-hatch phenotypes. An adaptive response to the presence of multiple insecticide classes necessarily involves the development of multiple resistance mechanisms whose effectiveness may be enhanced by intra-population variation in the expression of resistance phenotypes. The variation in the expression of insecticide resistance in association with selection for larval time-to-hatch may induce this kind of enhanced adaptive plasticity as a consequence of pleiotropy, whereby mosquitoes are able to complete their aquatic life stages in a variable breeding environment using staggered larval time-to-hatch, giving rise to an adult population with enhanced variation in the expression of insecticide resistance.

LABORATORY EVOLUTION OF LIFE-HISTORY TRAITS IN THE BEAN WEEVIL (ACANTHOSCELIDES OBTECTUS): THE EFFECTS OF DENSITY-DEPENDENT AND AGE-SPECIFIC SELECTION.

PubMed

Tucić, Nikola; Stojković, Oliver; Gliksman, Ivana; Milanović, Agana; Šešlija, Darka

1997-12-01

Four types of laboratory populations of the bean weevil (Acanthoscelides obtectus) have been developed to study the effects of density-dependent and age-specific selection. These populations have been selected at high (K) and low larval densities (r) as well as for reproduction early (Y) and late (O) in life. The results presented here suggest that the r- and K-populations (density-dependent selection regimes) have differentiated from each other with respect to the following life-history traits: egg-to-adult viability at high larval density (K > r), preadult developmental time (r > K), body weight (r > K), late fecundity (K > r), total realized fecundity (r > K), and longevity of males (r > K). It was also found that the following traits responded in statistically significant manner in populations subjected to different age-specific selection regimes: egg-to-adult viability (O > Y), body weight (O > Y), early fecundity (Y > O), late fecundity (O > Y), and longevity of females and males (O > Y). Although several life-history traits (viability, body weight, late fecundity) responded in similar manner to both density-dependent and age-specific selection regimes, it appears that underlying genetic and physiological mechanisms responsible for differentiation of the r/K and Y/O populations are different. We have also tested quantitative genetic basis of the bean weevil life-history traits in the populations experiencing density-dependent and age-specific selection. Among the traits traded-off within age-specific selection regimes, only early fecundity showed directional dominance, whereas late fecundity and longevity data indicated additive inheritance. In contrast to age-specific selecton regimes, three life-history traits (developmental time, body size, total fecundity) in the density-sependent regimes exhibited significant dominance effects. Lastly, we have tested the congruence between short-term and long-term effects of larval densities. The comparisons of the outcomes of the r/K selection regimes and those obtained from the low- and high-larval densities revealed that there is no congruence between the selection results and phenotypic plasticity for the analyzed life-history traits in the bean weevil. © 1997 The Society for the Study of Evolution.

Embryogenesis and Larval Biology of the Cold-Water Coral Lophelia pertusa

PubMed Central

Strömberg, Susanna M.; Dahl, Mikael P.; Lundälv, Tomas; Brooke, Sandra

2014-01-01

Cold-water coral reefs form spectacular and highly diverse ecosystems in the deep sea but little is known about reproduction, and virtually nothing about the larval biology in these corals. This study is based on data from two locations of the North East Atlantic and documents the first observations of embryogenesis and larval development in Lophelia pertusa, the most common framework-building cold-water scleractinian. Embryos developed in a more or less organized radial cleavage pattern from ∼160 µm large neutral or negatively buoyant eggs, to 120–270 µm long ciliated planulae. Embryogenesis was slow with cleavage occurring at intervals of 6–8 hours up to the 64-cell stage. Genetically characterized larvae were sexually derived, with maternal and paternal alleles present. Larvae were active swimmers (0.5 mm s−1) initially residing in the upper part of the water column, with bottom probing behavior starting 3–5 weeks after fertilization. Nematocysts had developed by day 30, coinciding with peak bottom-probing behavior, and possibly an indication that larvae are fully competent to settle at this time. Planulae survived for eight weeks under laboratory conditions, and preliminary results indicate that these planulae are planktotrophic. The late onset of competency and larval longevity suggests a high dispersal potential. Understanding larval biology and behavior is of paramount importance for biophysical modeling of larval dispersal, which forms the basis for predictions of connectivity among populations. PMID:25028936

Larval cases of caddisfly (Insecta: Trichoptera) affinity in Early Permian marine environments of Gondwana

NASA Astrophysics Data System (ADS)

Mouro, Lucas D.; Zatoń, Michał; Fernandes, Antonio C. S.; Waichel, Breno L.

2016-01-01

Caddisflies (Trichoptera) are small, cosmopolitan insects closely related to the Lepidoptera (moths and butterflies). Most caddisflies construct protective cases during their larval development. Although the earliest recognisable caddisflies date back to the early Mesozoic (Early and Middle Triassic), being particularly numerous and diverse during the Late Jurassic and Early Cretaceous, the first records of their larval case constructions are known exclusively from much younger, Early to Middle Jurassic non-marine deposits in the northern hemisphere. Here we present fossils from the Early Permian (Asselian-Sakmarian) marine deposits of Brazil which have strong morphological and compositional similarity to larval cases of caddisflies. If they are, which is very probable, these finds not only push back the fossil record of true caddisflies, but also indicate that their larvae constructed cases at the very beginning of their evolution in marine environments. Since modern caddisflies that construct larval cases in marine environments are only known from eastern Australia and New Zealand, we suggest that this marine ecology may have first evolved in western Gondwana during the Early Permian and later spread across southern Pangea.

Larval cases of caddisfly (Insecta: Trichoptera) affinity in Early Permian marine environments of Gondwana

PubMed Central

Mouro, Lucas D.; Zatoń, Michał; Fernandes, Antonio C.S.; Waichel, Breno L.

2016-01-01

Caddisflies (Trichoptera) are small, cosmopolitan insects closely related to the Lepidoptera (moths and butterflies). Most caddisflies construct protective cases during their larval development. Although the earliest recognisable caddisflies date back to the early Mesozoic (Early and Middle Triassic), being particularly numerous and diverse during the Late Jurassic and Early Cretaceous, the first records of their larval case constructions are known exclusively from much younger, Early to Middle Jurassic non-marine deposits in the northern hemisphere. Here we present fossils from the Early Permian (Asselian–Sakmarian) marine deposits of Brazil which have strong morphological and compositional similarity to larval cases of caddisflies. If they are, which is very probable, these finds not only push back the fossil record of true caddisflies, but also indicate that their larvae constructed cases at the very beginning of their evolution in marine environments. Since modern caddisflies that construct larval cases in marine environments are only known from eastern Australia and New Zealand, we suggest that this marine ecology may have first evolved in western Gondwana during the Early Permian and later spread across southern Pangea. PMID:26765261

Larval cases of caddisfly (Insecta: Trichoptera) affinity in Early Permian marine environments of Gondwana.

PubMed

Mouro, Lucas D; Zatoń, Michał; Fernandes, Antonio C S; Waichel, Breno L

2016-01-14

Caddisflies (Trichoptera) are small, cosmopolitan insects closely related to the Lepidoptera (moths and butterflies). Most caddisflies construct protective cases during their larval development. Although the earliest recognisable caddisflies date back to the early Mesozoic (Early and Middle Triassic), being particularly numerous and diverse during the Late Jurassic and Early Cretaceous, the first records of their larval case constructions are known exclusively from much younger, Early to Middle Jurassic non-marine deposits in the northern hemisphere. Here we present fossils from the Early Permian (Asselian-Sakmarian) marine deposits of Brazil which have strong morphological and compositional similarity to larval cases of caddisflies. If they are, which is very probable, these finds not only push back the fossil record of true caddisflies, but also indicate that their larvae constructed cases at the very beginning of their evolution in marine environments. Since modern caddisflies that construct larval cases in marine environments are only known from eastern Australia and New Zealand, we suggest that this marine ecology may have first evolved in western Gondwana during the Early Permian and later spread across southern Pangea.

Riceland mosquito management practices for Anopheles quadrimaculatus larvae.

PubMed

Allen, R A; Wilkes, W W; Lewis, C N; Meisch, M V

2008-12-01

Two separate but related studies were conducted regarding management of Anopheles quadrimaculatus larval populations in commercial rice fields near Cleveland, MS, in 2004. Study 1 was to evaluate the effectiveness of 2 treatments of aerially applied ultra-low volume applications of Bacillus thuringiensis var. israelensis (Bti) against An. quadrimaculatus larvae in dense, high-canopy mid- to late-season rice crop. Study 2 was to investigate the effect of preflood treatments of lambda-cyhalothrin (Karate), which is commonly used against rice water weevil (Lissorhoptrus oryzophilus), on An. quadrimaculatus larvae. Excellent initial, but short residual control (>99% control 1 day after treatment) was observed in the Bti-treated fields in both mid- and late-season rice. Little or no effect on mosquito larvae was observed in the lambda-cyhalothrin-treated fields. Results indicate that Bti can be effectively used by mosquito management personnel to control larval populations of An. quadrimaculatus in late-season rice fields; however, lambda-cyhalothrin did not effectively control larval An. quadrimaculatus when applied preflood to rice fields.

Volatile emissions from Aesculus hippocastanum induced by mining of larval stages of Cameraria ohridella influence oviposition by conspecific females.

PubMed

Johne, A Bettina; Weissbecker, Bernhard; Schütz, Stefan

2006-10-01

Larval stages of the horse chestnut leafminer Cameraria ohridella can completely destroy the surface of horse chestnut leaves, Aesculus hippocastanum. This study investigated the effect of the degree of leaf browning caused by the insect's larvae on olfactory detection, aggregation, and oviposition of C. ohridella adults. The influence of A. hippocastanum flower scent on oviposition of the first generation was also evaluated. Utilizing gas chromatography coupled with parallel detection by mass spectrometry and electroantennography (GC-MS/EAD), more than 30 compounds eliciting responses from antennae of C. ohridella were detected. Oviposition and mining by C. ohridella caused significant changes in the profile of leaf volatiles of A. hippocastanum. After oviposition and subsequent mining by early larval stages (L1-L3), substances such as benzaldehyde, 1,8-cineole, benzyl alcohol, 2-phenylethanol, methyl salicylate, (E)-beta-caryophyllene, and (E,E)-alpha-farnesene were emitted in addition to the compounds emitted by uninfested leaves. Insects were able to detect these compounds. The emitted amount of these substances increased with progressive larval development. During late larval stages (L4, L5) and severe loss of green leaf area, (E,E)-2,4-hexadienal, (E/Z)-linalool oxide (furanoid), nonanal, and decanal were also released by leaves. These alterations of the profile of volatiles caused modifications in aggregation of C. ohridella on leaves. In choice tests, leaves in early infestation stages showed no significant effect on aggregation, whereas insects avoided leaves in late infestation stages. Further choice tests with leaves treated with single compounds led to the identification of substances mediating an increase or decrease in oviposition.

Identification of Late Larval Stage Developmental Checkpoints in Caenorhabditis elegans Regulated by Insulin/IGF and Steroid Hormone Signaling Pathways

PubMed Central

Schindler, Adam J.; Baugh, L. Ryan; Sherwood, David R.

2014-01-01

Organisms in the wild develop with varying food availability. During periods of nutritional scarcity, development may slow or arrest until conditions improve. The ability to modulate developmental programs in response to poor nutritional conditions requires a means of sensing the changing nutritional environment and limiting tissue growth. The mechanisms by which organisms accomplish this adaptation are not well understood. We sought to study this question by examining the effects of nutrient deprivation on Caenorhabditis elegans development during the late larval stages, L3 and L4, a period of extensive tissue growth and morphogenesis. By removing animals from food at different times, we show here that specific checkpoints exist in the early L3 and early L4 stages that systemically arrest the development of diverse tissues and cellular processes. These checkpoints occur once in each larval stage after molting and prior to initiation of the subsequent molting cycle. DAF-2, the insulin/insulin-like growth factor receptor, regulates passage through the L3 and L4 checkpoints in response to nutrition. The FOXO transcription factor DAF-16, a major target of insulin-like signaling, functions cell-nonautonomously in the hypodermis (skin) to arrest developmental upon nutrient removal. The effects of DAF-16 on progression through the L3 and L4 stages are mediated by DAF-9, a cytochrome P450 ortholog involved in the production of C. elegans steroid hormones. Our results identify a novel mode of C. elegans growth in which development progresses from one checkpoint to the next. At each checkpoint, nutritional conditions determine whether animals remain arrested or continue development to the next checkpoint. PMID:24945623

Postharvest irradiation treatment for quarantine control of the invasive Lobesia botrana (Lepidoptera: Tortricidae)

USDA-ARS?s Scientific Manuscript database

The effects of irradiation on egg, larval, and pupal development in European grapevine moth, Lobesia botrana (Lepidoptera: Tortricidae), were examined. Eggs, neonates, third instars, fifth instars, and early and late stage pupae were irradiated at target doses of 50, 100, 150, or 200 Gy or left untr...

Developmental Progression in the Coral Acropora digitifera Is Controlled by Differential Expression of Distinct Regulatory Gene Networks

PubMed Central

Reyes-Bermudez, Alejandro; Villar-Briones, Alejandro; Ramirez-Portilla, Catalina; Hidaka, Michio; Mikheyev, Alexander S.

2016-01-01

Corals belong to the most basal class of the Phylum Cnidaria, which is considered the sister group of bilaterian animals, and thus have become an emerging model to study the evolution of developmental mechanisms. Although cell renewal, differentiation, and maintenance of pluripotency are cellular events shared by multicellular animals, the cellular basis of these fundamental biological processes are still poorly understood. To understand how changes in gene expression regulate morphogenetic transitions at the base of the eumetazoa, we performed quantitative RNA-seq analysis during Acropora digitifera’s development. We collected embryonic, larval, and adult samples to characterize stage-specific transcription profiles, as well as broad expression patterns. Transcription profiles reconstructed development revealing two main expression clusters. The first cluster grouped blastula and gastrula and the second grouped subsequent developmental time points. Consistently, we observed clear differences in gene expression between early and late developmental transitions, with higher numbers of differentially expressed genes and fold changes around gastrulation. Furthermore, we identified three coexpression clusters that represented discrete gene expression patterns. During early transitions, transcriptional networks seemed to regulate cellular fate and morphogenesis of the larval body. In late transitions, these networks seemed to play important roles preparing planulae for switch in lifestyle and regulation of adult processes. Although developmental progression in A. digitifera is regulated to some extent by differential coexpression of well-defined gene networks, stage-specific transcription profiles appear to be independent entities. While negative regulation of transcription is predominant in early development, cell differentiation was upregulated in larval and adult stages. PMID:26941230

Roles of insulin-like growth factors in metamorphic development of turbot (Scophthalmus maximus).

PubMed

Jia, Yudong

2018-01-31

Larval turbot (Scophthalmus maximus) undergo metamorphosis, a late post-embryonic developmental event that precedes juvenile transition. Insulin-like growth factors (IGFs) are important endocrine/autocrine/paracrine factors that provide essential signals to control of the embryonic and postnatal development of vertebrate species, including fish. Accumulating evidence suggests that IGFs are involved in regulating the metamorphic development of flatfish. This mini review focus on the functions of all known IGFs (IGF-I and IGF-II) during the metamorphic development of turbot. Information about IGFs and insulin-like growth factors binding proteins (IGFBPs) from other teleosts is also included in this review to provide an overview of IGFs functions in the metamorphic development of turbot. These findings may enhance our understanding of the potential roles of the IGFs system in controlling of flatfish metamorphosis and contributing to the improvement of broodstock management strategies for larval turbot. Copyright © 2018 Elsevier Inc. All rights reserved.

Larvicidal Activity of Citrus Limonoids against Aedes albopictus Larvae.

PubMed

Bilal, Hazrat; Akram, Waseem; Ali-Hassan, Soaib

2012-12-01

Development of insecticide resistance occurred due to the continuous and misuse of synthetic insecticides therefore, the recent study was conducted to explore eco-friendly plant extracts that have some potential to suppress mosquito larval population. WHO recommended mosquito larval bioassay method for insecticide was used while for the analysis of citrus oils for limonin and nomilin content HPLC was used. Among the two citrus cultivars tested as larvicide against Aedes albopictus, valencia late (Citrus sinensis) was the best in terms of LC(50) (297 ppm), % mortality (97%) and LT(50) (18.49 hours) then freutrall early (Citrus reticulate) with LC(50) (377.4 ppm), % mortality (88%) and LT(50) (31 hours), While nomilin gave lowest LC(50) (121.04 ppm) than limonin (382.22 ppm) after 72 hours of exposure. Valencia late also had more limonin and nomilin (377 μg/ml and 21.19 μg/ml) than freutrall early (5.29 μg/ml and 3.89 μg/ml) respectively. Valencia late showed best results in term of LC(50), LT(50) and percentage mortality against Aedes albopictus as it has more amount of nomilin then freutrall early, however further evaluation in the field conditions is required.

Larvicidal Activity of Citrus Limonoids against Aedes albopictus Larvae

PubMed Central

Bilal, Hazrat; Akram, Waseem; Ali-Hassan, Soaib

2012-01-01

Background: Development of insecticide resistance occurred due to the continuous and misuse of synthetic insecticides therefore, the recent study was conducted to explore eco-friendly plant extracts that have some potential to suppress mosquito larval population. Methods: WHO recommended mosquito larval bioassay method for insecticide was used while for the analysis of citrus oils for limonin and nomilin content HPLC was used. Results: Among the two citrus cultivars tested as larvicide against Aedes albopictus, valencia late (Citrus sinensis) was the best in terms of LC50 (297 ppm), % mortality (97%) and LT50 (18.49 hours) then freutrall early (Citrus reticulate) with LC50 (377.4 ppm), % mortality (88%) and LT50 (31 hours), While nomilin gave lowest LC50 (121.04 ppm) than limonin (382.22 ppm) after 72 hours of exposure. Valencia late also had more limonin and nomilin (377 μg/ml and 21.19 μg/ml) than freutrall early (5.29 μg/ml and 3.89 μg/ml) respectively. Conclusion: Valencia late showed best results in term of LC50, LT50 and percentage mortality against Aedes albopictus as it has more amount of nomilin then freutrall early, however further evaluation in the field conditions is required. PMID:23378967

Higher thyroid hormone receptor expression correlates with short larval periods in spadefoot toads and increases metamorphic rate

PubMed Central

Hollar, Amy R.; Choi, Jinyoung; Grimm, Adam T.; Buchholz, Daniel R.

2011-01-01

Spadefoot toad species display extreme variation in larval period duration, due in part to evolution of thyroid hormone (TH) physiology. Specifically, desert species with short larval periods have higher tail tissue content of TH and exhibit increased responsiveness to TH. To address the molecular basis of larval period differences, we examined TH receptor (TR) expression across species. Based on the dual function model for the role of TR in development, we hypothesized that desert spadefoot species with short larval periods would have 1) late onset of TR expression prior to the production of endogenous TH and 2) higher TR levels when endogenous TH becomes available. To test these hypotheses, we cloned fragments of TRα and TRβ genes from the desert spadefoot toads Scaphiopus couchii and Spea multiplicata and their non-desert relative Pelobates cultripes and measured their mRNA levels in tails using quantitative PCR in the absence (premetamorphosis) or presence (natural metamorphosis) of TH. All species express TRα and TRβ from the earliest stages measured (from just after hatching), but S. couchii, which has the shortest larval period, had more TRα throughout development compared to P. cultripes, which has the longest larval period. TRβ mRNA levels were similar across species. Exogenous T3 treatment induced faster TH-response gene expression kinetics in S. couchii compared to the other species, consistent with its increased TRα mRNA expression and indicative of a functional consequence of more TRα activity at the molecular level. To directly test whether higher TRα expression may contribute to shorter larval periods, we overexpressed TRα via plasmid injection into tail muscle cells of the model frog Xenopus laevis and found an increased rate of muscle cell death in response to TH. These results suggest that increased TRα expression evolved in S. couchii and contribute to its higher metamorphic rates. PMID:21651912

A Novel Ecdysone Receptor Mediates Steroid-Regulated Developmental Events during the Mid-Third Instar of Drosophila

PubMed Central

Costantino, Benjamin F. B.; Bricker, Daniel K.; Alexandre, Kelly; Shen, Kate; Merriam, John R.; Antoniewski, Christophe; Callender, Jenna L.; Henrich, Vincent C.; Presente, Asaf; Andres, Andrew J.

2008-01-01

The larval salivary gland of Drosophila melanogaster synthesizes and secretes glue glycoproteins that cement developing animals to a solid surface during metamorphosis. The steroid hormone 20-hydroxyecdysone (20E) is an essential signaling molecule that modulates most of the physiological functions of the larval gland. At the end of larval development, it is known that 20E—signaling through a nuclear receptor heterodimer consisting of EcR and USP—induces the early and late puffing cascade of the polytene chromosomes and causes the exocytosis of stored glue granules into the lumen of the gland. It has also been reported that an earlier pulse of hormone induces the temporally and spatially specific transcriptional activation of the glue genes; however, the receptor responsible for triggering this response has not been characterized. Here we show that the coordinated expression of the glue genes midway through the third instar is mediated by 20E acting to induce genes of the Broad Complex (BRC) through a receptor that is not an EcR/USP heterodimer. This result is novel because it demonstrates for the first time that at least some 20E-mediated, mid-larval, developmental responses are controlled by an uncharacterized receptor that does not contain an RXR-like component. PMID:18566664

Representation of particle motion in the auditory midbrain of a developing anuran.

PubMed

Simmons, Andrea Megela

2015-07-01

In bullfrog tadpoles, a "deaf period" of lessened responsiveness to the pressure component of sounds, evident during the end of the late larval period, has been identified in the auditory midbrain. But coding of underwater particle motion in the vestibular medulla remains stable over all of larval development, with no evidence of a "deaf period." Neural coding of particle motion in the auditory midbrain was assessed to determine if a "deaf period" for this mode of stimulation exists in this brain area in spite of its absence from the vestibular medulla. Recording sites throughout the developing laminar and medial principal nuclei show relatively stable thresholds to z-axis particle motion, up until the "deaf period." Thresholds then begin to increase from this point up through the rest of metamorphic climax, and significantly fewer responsive sites can be located. The representation of particle motion in the auditory midbrain is less robust during later compared to earlier larval stages, overlapping with but also extending beyond the restricted "deaf period" for pressure stimulation. The decreased functional representation of particle motion in the auditory midbrain throughout metamorphic climax may reflect ongoing neural reorganization required to mediate the transition from underwater to amphibious life.

The two origins of hemocytes in Drosophila.

PubMed

Holz, Anne; Bossinger, Barbara; Strasser, Thomas; Janning, Wilfried; Klapper, Robert

2003-10-01

As in many other organisms, the blood of Drosophila consists of several types of hemocytes, which originate from the mesoderm. By lineage analyses of transplanted cells, we specified two separate anlagen that give rise to different populations of hemocytes: embryonic hemocytes and lymph gland hemocytes. The anlage of the embryonic hemocytes is restricted to a region within the head mesoderm between 70 and 80% egg length. In contrast to all other mesodermal cells, the cells of this anlage are already determined as hemocytes at the blastoderm stage. Unexpectedly, these hemocytes do not degenerate during late larval stages, but have the capacity to persist through metamorphosis and are still detectable in the adult fly. A second anlage, which gives rise to additional hemocytes at the onset of metamorphosis, is located within the thoracic mesoderm at 50 to 53% egg length. After transplantation within this region, clones were detected in the larval lymph glands. Labeled hemocytes are released by the lymph glands not before the late third larval instar. The anlage of these lymph gland-derived hemocytes is not determined at the blastoderm stage, as indicated by the overlap of clones with other tissues. Our analyses reveal that the hemocytes of pupae and adult flies consist of a mixture of embryonic hemocytes and lymph gland-derived hemocytes, originating from two distinct anlagen that are determined at different stages of development.

Oviposition Site Selection by the Dengue Vector Aedes aegypti and Its Implications for Dengue Control

PubMed Central

Wong, Jacklyn; Stoddard, Steven T.; Astete, Helvio; Morrison, Amy C.; Scott, Thomas W.

2011-01-01

Background Because no dengue vaccine or antiviral therapy is commercially available, controlling the primary mosquito vector, Aedes aegypti, is currently the only means to prevent dengue outbreaks. Traditional models of Ae. aegypti assume that population dynamics are regulated by density-dependent larval competition for food and little affected by oviposition behavior. Due to direct impacts on offspring survival and development, however, mosquito choice in oviposition site can have important consequences for population regulation that should be taken into account when designing vector control programs. Methodology/Principal Findings We examined oviposition patterns by Ae. aegypti among 591 naturally occurring containers and a set of experimental containers in Iquitos, Peru. Using larval starvation bioassays as an indirect measure of container food content, we assessed whether females select containers with the most food for their offspring. Our data indicate that choice of egg-laying site is influenced by conspecific larvae and pupae, container fill method, container size, lid, and sun exposure. Although larval food positively influenced oviposition, our results did not support the hypothesis that females act primarily to maximize food for larvae. Females were most strongly attracted to sites containing immature conspecifics, even when potential competitors for their progeny were present in abundance. Conclusion/Significance Due to strong conspecific attraction, egg-laying behavior may contribute more to regulating Ae. aegypti populations than previously thought. If highly infested containers are targeted for removal or larvicide application, females that would have preferentially oviposited in those sites may instead distribute their eggs among other suitable, previously unoccupied containers. Strategies that kill mosquitoes late in their development (i.e., insect growth regulators that kill pupae rather than larvae) will enhance vector control by creating “egg sinks,” treated sites that exploit conspecific attraction of ovipositing females, but reduce emergence of adult mosquitoes via density-dependent larval competition and late acting insecticide. PMID:21532736

[Agglutination and phagocytosis of foreign abiotic particles by hemocytes of the blowely, Calliphora vicina in vivo. I. Dynamics of hemocyte activity during larval development].

PubMed

Kind, T V

2005-01-01

Three types of Calliphora larval hemocytes have been revealed to be involved in phagocytosis of abiotic foreign particles: thrombocytoids, larval plasmatocytes and plasmatocytes I. Thrombocytoids are the quickest to respond to the appearance of invaders. The onset of test particle entrapment by thrombocytoid cytoplasmic fragments was observed, depending on the larval age within 0.5-5.0 min after injection. Separated fragments were fused, forming strands or roundish agglutinates. Phagocytosis of carbon, carmine or Indian ink particles by larval plasmatocytes occurs far more lately, and no earlier than 20-30 min after injection. Plasmatocytes I are capable of foreign particles adhesion on their surface, with a subsequent morule formation, and of engulfing these particles. These two events start in different time periods: adhesion occurs in 5-10 min, while phagocytosis is observed in 1--3 h. The rate of test particle entrapment and stability of agglutinales clearly depends on the larval age. The most pronounced reaction of hemocytes to foreign particles may be observed by the end of feeding and crop emptying. The second, somewhat less expressed rise of activity occurs in mature larvae not long before the onset of pupariation. Diapause induction is accompanied by reducing activities of both plasmatocytes and thrompocytoids. The importance of different hemocyte types in cellular immune reaction of Calliphora vicina larvae, and co-ordination between plasmatocytes and thrombocytoids are discussed.

Estuarine retention of larvae of the crab Rhithropanopeus harrisii

NASA Astrophysics Data System (ADS)

Cronin, Thomas W.

1982-08-01

Larvae of estuarine organisms continually face possible export from the parent estuary. Retention of larvae of the estuarine crab Rhithropanopeus harrisii was investigated in the upper Newport River estuary, North Carolina. All of the developmental stages occurred in the same area of the estuary with similar horizontal distributions, and the concentrations of intermediate and late stages were not greatly reduced from those of the first larval stage. This was strong evidence for the continuous retention of larvae in the upper estuary. To determine mechanisms by which retention might be effected, field studies of the vertical distributions and migrations of these larvae were made. The four zoeal stages had similar but complex vertical migration patterns, which varied from study to study. These migrations centered on the depth of no net flow, reducing longitudinal transport during development. Cross-spectral analysis of the larval migrations and the environmental cycles of light, salinity and current speed revealed that each of these external cycles affected larval depth. Megalopae of R. harrisii also migrated vertically, but they were present in much lower concentrations than the zoeal stages, an indication of a change to benthic existence in this final larval form.

Fish Inner Ear Otolith Growth Under Real Microgravity (Spaceflight) and Clinorotation

NASA Astrophysics Data System (ADS)

Anken, Ralf; Brungs, Sonja; Grimm, Dennis; Knie, Miriam; Hilbig, Reinhard

2016-06-01

Using late larval stages of cichlid fish ( Oreochromis mossambicus) we have shown earlier that the biomineralization of otoliths is adjusted towards gravity by means of a neurally guided feedback loop. Centrifuge experiments, e.g., revealed that increased gravity slows down otolith growth. Microgravity thus should yield an opposite effect, i.e., larger than normal otoliths. Consequently, late larval cichlids (stage 14, vestibular system operational) were subjected to real microgravity during the 12 days FOTON-M3 spaceflight mission (OMEGAHAB-hardware). Controls were kept at 1 g on ground within an identical hardware. Animals of another batch were subsequently clinorotated within a submersed fast-rotating clinostat with one axis of rotation (2d-clinostat), a device regarded to simulate microgravity. Temperature and light conditions were provided in analogy to the spaceflight experiment. Controls were maintained at 1 g within the same aquarium. After all experiments, animals had reached late stage 21 (fish can swim freely). Maintenance under real microgravity during spaceflight resulted in significantly larger than normal otoliths (both lapilli and sagittae, involved in sensing gravity and the hearing process, respectively). This result is fully in line with an earlier spaceflight study in the course of which otoliths from late-staged swordtails Xiphophorus helleri were analyzed. Clinorotation resulted in larger than 1 g sagittae. However, no effect on lapilli was obtained. Possibly, an effect was present but too light to be measurable. Overall, spaceflight obviously induces an adaptation of otolith growth, whereas clinorotation does not fully mimic conditions of microgravity regarding late larval cichlids.

Modelling the transport of common sole larvae in the southern North Sea: Influence of hydrodynamics and larval vertical movements

NASA Astrophysics Data System (ADS)

Savina, Marie; Lacroix, Geneviève; Ruddick, Kevin

2010-04-01

In the present work we used a particle-tracking model coupled to a 3D hydrodynamic model to study the combined effect of hydrodynamic variability and active vertical movements on the transport of sole larvae in the southern North Sea. Larval transport from the 6 main spawning grounds was simulated during 40 day periods starting on 2 plausible spawning dates, the 15/04 and the 01/05, during 2 years, 1995 and 1996. In addition to a "passive" behaviour, 3 types of active vertical movements inspired from previous studies have been tested: (1) Eggs and early larvae float in the surface waters, late larvae migrate toward the bottom and stay there until the end of the simulation; (2 and 3) Eggs float in the surface waters, early larvae perform diel vertical migrations in the surface waters, and (2) Late larvae perform diel vertical migrations in the bottom waters until the end of the simulation; or (3) Late larvae perform tidally synchronised vertical migrations in the bottom waters until the end of the simulation. These behaviours have been implemented in the model with vertical migration rates, positive or negative, which can account for buoyancy or real swimming activity. Variations in larval transport were analysed in terms of mean trajectories, final larvae distribution, larval retention above nurseries, and connectivity. Results suggest that the variations in larval retention above nurseries due to the varying hydrodynamic conditions are not consistent in space i.e. not the same for all the spawning sites. The effect of active vertical movements on larval transport is also not consistent in space: Effects of active vertical movements include decreased retention above nurseries, decreased transport and/or decreased horizontal dispersion of larvae through reduced vertical shear (depending on the zone). The variability in larval retention due to hydrodynamic variability is higher than variability due to differences in the behaviour of larvae. In terms of connectivity, exchanges of larvae between the 6 areas considered are moderate: 10 connections happened out of the 30 possible, and the amount of larvae exchanged is much lower than the amount of larvae retained except in a few cases. This is not incompatible with the possible existence of subpopulations of sole in the Eastern Channel and southern North Sea.

C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability.

PubMed

Korzelius, Jerome; The, Inge; Ruijtenberg, Suzan; Portegijs, Vincent; Xu, Huihong; Horvitz, H Robert; van den Heuvel, Sander

2011-02-15

DNA replication and its connection to M phase restraint are studied extensively at the level of single cells but rarely in the context of a developing animal. C. elegans lin-6 mutants lack DNA synthesis in postembryonic somatic cell lineages, while entry into mitosis continues. These mutants grow slowly and either die during larval development or develop into sterile adults. We found that lin-6 corresponds to mcm-4 and encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex. The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase. Induction of cell cycle entry and differentiation continues in developing mcm-4 larvae, even in cells that went through abortive division. In contrast to somatic cells in mcm-4 mutants, the gonad continues DNA replication and cell division until late larval development. Expression of MCM-4 in the epidermis (also known as hypodermis) is sufficient to rescue the growth retardation and lethality of mcm-4 mutants. While the somatic gonad and germline show substantial ability to cope with lack of zygotic mcm-4 function, mcm-4 is specifically required in the epidermis for growth and survival of the whole organism. Thus, C. elegans mcm-4 has conserved functions in DNA replication and replication checkpoint control but also shows unexpected tissue-specific requirements. Copyright © 2010 Elsevier Inc. All rights reserved.

C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability

PubMed Central

Korzelius, Jerome; The, Inge; Ruijtenberg, Suzan; Portegijs, Vincent; Xu, Huihong; Horvitz, H. Robert; van den Heuvel, Sander

2012-01-01

DNA replication and its connection to M phase restraint are studied extensively at the level of single cells but rarely in the context of a developing animal. C. elegans lin-6 mutants lack DNA synthesis in postembryonic somatic cell lineages, while entry into mitosis continues. These mutants grow slowly and either die during larval development or develop into sterile adults. We found that lin-6 corresponds to mcm-4 and encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex. The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase. Induction of cell-cycle entry and differentiation continues in developing mcm-4 larvae, even in cells that went through abortive division. In contrast to somatic cells in mcm-4 mutants, the gonad continues DNA replication and cell division until late larval development. Expression of MCM-4 in the epidermis (also known as hypodermis) is sufficient to rescue the growth retardation and lethality of mcm-4 mutants. While the somatic gonad and germline show substantial ability to cope with lack of zygotic mcm-4 function, mcm-4 is specifically required in the epidermis for growth and survival of the whole organism. Thus, C. elegans mcm-4 has conserved functions in DNA replication and replication checkpoint control but also shows unexpected tissue-specific requirements. PMID:21146520

The ecology and larval habitats characteristics of anopheline mosquitoes (Diptera: Culicidae) in Aligudarz County (Luristan province, western Iran)

PubMed Central

Amani, Hamid; Yaghoobi-Ershadi, Mohammad Reza; Kassiri, Hamid

2014-01-01

Objective To determine ecology and characteristics of the larval habitats of the genus Anopheles (Dipetra: Culicidae) in Aligudarz County, western Iran. Methods This descriptive cross-sectional research was carried out to study the anopheline larvae ecology in seven rural districts, Aligudarz County, from late April to late November 1997. Larvae were captured using the dipping method. Larval breeding places characteristics were noted according to water situation (turbid or clean, stagnant or running), substrate type, site type (man-made or natural), sunlight situation, site situation (transient or permanent, with or without vegetation). Results A total of 9 620 3rd and 4th instar larvae of Anopheles from 115 breeding places in 22 villages were captured, which belonged to the following species: Anopheles stephensi, Anopheles d'thali, Anopheles apoci, Anopheles superpictus (forms A and B), Anopheles marterii sogdianus, Anopheles turkhodi, Anopheles maculipennis S.L and Anopheles claviger. Anopheles stephensi, Anopheles maculipennis S.L and Anopheles apoci were collected for the first time in this county. Anopheles superpictus (93.18%) was the most prevailed one and dispersed over the entire region. Larval habitats consisted of nine natural and three artificial larval habitats. The most important larval habitats were river edges (54.8%), rice fields (12.2%), and grassland (8.7%) with permanent or transient, stagnant or running and clean water, with or without vegetation, sand or mud substrate in full sunlight area. Conclusions Regarding this research, river edges and rice fields are the most important breeding places of malaria vectors in Aligudarz County. It is worthy of note in larvicidal programs. PMID:25183088

Hydroxyurea-mediated neuroblast ablation establishes birthdates of secondary lineages and addresses neuronal interactions in the developing Drosophila brain

PubMed Central

Lovick, Jennifer K.; Hartenstein, Volker

2015-01-01

The Drosophila brain is comprised of neurons formed by approximately 100 lineages, each of which is derived from a stereotyped, asymmetrically dividing neuroblast. Lineages serve as structural and developmental units of Drosophila brain anatomy and reconstruction of lineage projection patterns represents a suitable map of Drosophila brain circuitry at the level of neuron populations (“macro-circuitry”). Two phases of neuroblast proliferation, the first in the embryo and the second during the larval phase (following a period of mitotic quiescence), produce primary and secondary lineages, respectively. Using temporally controlled pulses of hydroxyurea (HU) to ablate neuroblasts and their corresponding secondary lineages during the larval phase, we analyzed the effect on development of primary and secondary lineages in the late larval and adult brain. Our findings indicate that timing of neuroblast re-activation is highly stereotyped, allowing us to establish “birth dates” for all secondary lineages. Furthermore, our results demonstrate that, whereas the trajectory and projection pattern of primary and secondary lineages is established in a largely independent manner, the final branching pattern of secondary neurons is dependent upon the presence of appropriate neuronal targets. Taken together, our data provide new insights into the degree of neuronal plasticity during Drosophila brain development. PMID:25773365

Temporal and cross-shelf distribution of ichthyoplankton in the central Cantabrian Sea

NASA Astrophysics Data System (ADS)

Rodriguez, J. M.

2008-09-01

Environmental variables have been measured and sampling for ichthyoplankton has been conducted monthly, since April 2001, at three stations, located at the inner (1), middle (2) and outer (3) shelf of the central Cantabrian Sea. This paper presents the results of the study of the ichthyoplankton collected from July 2001 to June 2004. Fish larvae from 99 species, belonging to 37 families, were identified. Families with higher number of species were Gadidae, Sparidae and Labridae. The larval fish assemblage was dominated by pelagic fish species, with Sardina pilchardus, as the most abundant. There was a pronounced spring peak in larval abundance, dominated by S. pilchardus. A smaller peak, dominated by S. pilchardus and Micromesistius poutassou, was recorded in late winter at Stns 2 and 3. This pattern was evident for the three-year study. Results also indicate that this study was limited to the coastal larval fish assemblage inhabiting the central Cantabrian Sea shelf. This assemblage was temporally structured into other three assemblages: winter, late winter-spring and summer-autumn. Temperature was apparently a key factor in larval fish assemblage succession. In a scenario of global warming, this study constitutes a basis to evaluating the ongoing changes in the pelagic coastal ecosystem of the central Cantabrian Sea.

Time of planting and choice of maize hybrids in controlling WCR (Diabrotica virgifera virgifera Le Conte) in Serbia and Montenegro.

PubMed

Baca, F; Videnovic, Z; Erski, P; Stankovic, R; Dobrikovic, Danica

2003-01-01

Effects of the length of growing season of maize hybrids (FAO maturity groups 400, 500, 600 and 700) and planting dates on the maize crop, as an attractive supplemental feeding for western corn rootworm (WCR) beetles and larval survival, were observed in two locations of South Banat, during a three-year (1997-1999) and a two-year period (2001 and 2002). The feeding attraction of the maize crop for WCR beetles and survival of larvae were evaluated in dependency of the variable "plant lodging". The following results were obtained: First location: A. Plant lodging over time of planting and applied insecticides. 1. Early planting: 44.2%, 77.6%, and 76.7% for FAO 400, 500 and 600, respectively. 2. Late planting: 4.7%, 14.9%, and 7.9% for FAO 400, 500 and 600, respectively. B. Plant lodging over time of planting and cropping practices: 1. Early planting without insecticide application 72.2%, and with insecticide application 7.3%. The efficacy of application of insecticide carbofurane (Furadan 350 FS, dosage 4.0 liter/ha) in larval control was 89.9%. 2. Late planting without insecticide application, plant lodging was 47.7%, and with insecticide application 8.1%. The efficacy of application of insecticide carbofurane (Furadan 350 FS, dosage 4.0 l/ha-1) in larval control was 83.0%. Early planting resulted in greater survival of larvae; hence plant lodging was 10 times greater in early than in late planting. The percentage of lodged plants indicates that the maize crop in late planting was more attractive to imagoes. Therefore, more lodged plants were observed in the treatment where late planting preceded. Second location: Plant lodging as dependent on "treatments" 1. Regular plantings: 90.7% in untreated control and 76.2% in insecticide treated variant. The efficacy of insecticide application in control of high larval population was 16.0%. 2. Replanting date: 12.2% in untreated and 4.4% in treated variant. The efficacy of insecticide in control of low larval population increased from 16.0 to 63.9%. To successfully decrease the size and intensity of attacks of the Diabrotica v. virgifera population under conditions of applying insecticides or not, it is necessary to use maize hybrids of the earliest possible maturity group and to plant the seed on the earliest date possible in the first year of growing maize, if maize is to be followed by maize in the next year.

Effects of hatching time for larval ambystomatid salamanders

USGS Publications Warehouse

Boone, M.D.; Scott, D.E.; Niewiarowski, P.H.

2002-01-01

In aquatic communities, the phenology of breeding may influence species interactions. In the early-breeding marbled salamander, Ambystoma opacum, timing of pond filling may determine whether interactions among larvae are competitive or predatory. The objectives of our studies were to determine how time of egg hatching affected size, larval period, and survival to metamorphosis in A. opacum, and if early-hatching in A. opacum influenced the competitive and predator-prey relationships with smaller larvae of the mole salamander, Ambystoma talpoideum. Salamander larvae were reared from hatching through metamorphosis in large, outdoor enclosures located in a natural temporary pond in Aiken County, South Carolina, in two experiments. In study 1, we reared early- and late-hatching A. opacum larvae separately from hatching through metamorphosis. In study 2, we examined how early- versus late-hatching A. opacum affected a syntopic species, A. talpoideum. In general, early-hatching A. opacum were larger and older at metamorphosis, had greater survival, and left the pond earlier than late-hatching larvae. Ambystoma talpoideum reared in the presence of early-hatching A. opacum had lower survival than in controls, suggesting that A. opacum may predate upon A. talpoideum when they gain a growth advantage over later-hatching larvae. Our studies demonstrate that time of pond filling and phenology of breeding may influence population dynamics and alter the nature of relationships that develop among species.

Development of the five primary podia from the coeloms of a sea star larva: homology with the echinoid echinoderms and other deuterostomes

PubMed Central

Morris, Valerie B.; Selvakumaraswamy, Paulina; Whan, Renée; Byrne, Maria

2009-01-01

Confocal laser scanning microscopy of larvae of the asteroid Parvulastra exigua was used to investigate the development of the five primary podia from the coeloms in the echinoderm phylum in an approach to the problem of morphological homology in the deuterostome phyla. The development is shown from an early brachiolaria larval stage to a pre-settlement late brachiolaria larval stage. In the early brachiolaria larva, a single enterocoele connected to the archenteron has formed into two lateral coeloms and an anterior coelom. The primary podia form from the coelomic regions on the left side of the brachiolaria larva, while on the right the coelomic regions connect with the exterior through the pore canal and hydropore. The anterior coelom forms the coelom of the brachia. Homology between the primary podia of the asteroid and the echinoid classes of echinoderms is described and extended to coeloms of other deuterostome phyla. PMID:19129140

Metamorphosis enhances the effects of metal exposure on the mayfly, Centroptilum triangulifer

USGS Publications Warehouse

Wesner, Jeff S.; Kraus, Johanna M.; Schmidt, Travis S.; Walters, David M.; Clements, William H.

2014-01-01

The response of larval aquatic insects to stressors such as metals is used to assess the ecological condition of streams worldwide. However, nearly all larval insects metamorphose from aquatic larvae to winged adults, and recent surveys indicate that adults may be a more sensitive indicator of stream metal toxicity than larvae. One hypothesis to explain this pattern is that insects exposed to elevated metal in their larval stages have a reduced ability to successfully complete metamorphosis. To test this hypothesis we exposed late-instar larvae of the mayfly, Centroptilum triangulifer, to an aqueous Zn gradient (32–476 μg/L) in the laboratory. After 6 days of exposure, when metamorphosis began, larval survival was unaffected by zinc. However, Zn reduced wingpad development at concentrations above 139 μg/L. In contrast, emergence of subimagos and imagos tended to decline with any increase in Zn. At Zn concentrations below 105 μg/L (hardness-adjusted aquatic life criterion), survival between the wingpad and subimago stages declined 5-fold across the Zn gradient. These results support the hypothesis that metamorphosis may be a survival bottleneck, particularly in contaminated streams. Thus, death during metamorphosis may be a key mechanism explaining how stream metal contamination can impact terrestrial communities by reducing aquatic insect emergence.

Dynamic genome wide expression profiling of Drosophila head development reveals a novel role of Hunchback in retinal glia cell development and blood-brain barrier integrity

PubMed Central

Torres-Oliva, Montserrat; Schneider, Julia; Wiegleb, Gordon

2018-01-01

Drosophila melanogaster head development represents a valuable process to study the developmental control of various organs, such as the antennae, the dorsal ocelli and the compound eyes from a common precursor, the eye-antennal imaginal disc. While the gene regulatory network underlying compound eye development has been extensively studied, the key transcription factors regulating the formation of other head structures from the same imaginal disc are largely unknown. We obtained the developmental transcriptome of the eye-antennal discs covering late patterning processes at the late 2nd larval instar stage to the onset and progression of differentiation at the end of larval development. We revealed the expression profiles of all genes expressed during eye-antennal disc development and we determined temporally co-expressed genes by hierarchical clustering. Since co-expressed genes may be regulated by common transcriptional regulators, we combined our transcriptome dataset with publicly available ChIP-seq data to identify central transcription factors that co-regulate genes during head development. Besides the identification of already known and well-described transcription factors, we show that the transcription factor Hunchback (Hb) regulates a significant number of genes that are expressed during late differentiation stages. We confirm that hb is expressed in two polyploid subperineurial glia cells (carpet cells) and a thorough functional analysis shows that loss of Hb function results in a loss of carpet cells in the eye-antennal disc. Additionally, we provide for the first time functional data indicating that carpet cells are an integral part of the blood-brain barrier. Eventually, we combined our expression data with a de novo Hb motif search to reveal stage specific putative target genes of which we find a significant number indeed expressed in carpet cells. PMID:29360820

Identification of Bombyx mori nucleopolyhedrovirus bm58a as an auxiliary gene and its requirement for cell lysis and larval liquefaction.

PubMed

Yang, Rui; Zhang, Jianjia; Feng, Min; Wu, Xiaofeng

2016-11-01

Bombyx mori nucleopolyhedrovirus orf58a (bm58a) and its homologues are highly conserved in genomes of all sequenced group I alphabaculoviruses and its function is still unknown. Transcriptional analysis revealed that bm58a is a very late gene initiated from a late transcriptional start motif TAAG. To examine its role in the virus, a bm58a knockout virus (vBmbm-58a-KO-PH-GFP) was generated through homologous recombination in Escherichia coli. Analysis of fluorescence microscopy, titration assays and electron microscopy examination showed that the deletion of bm58a did not affect viral replication and occlusion bodies formation in vitro, indicating that bm58a is not required for viral propagation. However, vBmbm-58a-KO-PH-GFP did not result in cell lysis when wild-type virus infected cells began to lyse, and the vBmbm-58a-KO-PH-GFP infected cells remained intact until 2 weeks post-infection. Quantification of polyhedra release from cells confirmed this observation. Accordingly, though deletion of bm58a did not reduce Bombyx mori nucleopolyhedrovirus infectivity in vivo in bioassays, it did significantly disrupt the larval liquefaction, reducing the level of polyhedra release from infected host. Immunofluorescence analysis demonstrated that Bm58a was predominantly localized on the cellular membrane at the late stage of infection, which may contribute to its function of facilitating cell lysis and larval liquefaction. Our results suggest that although bm58a is not essential for viral propagation as an auxiliary gene, it is a key factor of virus-induced cell lysis and larval liquefaction in vitro and in vivo.

Use of an activated beta-catenin to identify Wnt pathway target genes in caenorhabditis elegans, including a subset of collagen genes expressed in late larval development.

PubMed

Jackson, Belinda M; Abete-Luzi, Patricia; Krause, Michael W; Eisenmann, David M

2014-04-16

The Wnt signaling pathway plays a fundamental role during metazoan development, where it regulates diverse processes, including cell fate specification, cell migration, and stem cell renewal. Activation of the beta-catenin-dependent/canonical Wnt pathway up-regulates expression of Wnt target genes to mediate a cellular response. In the nematode Caenorhabditis elegans, a canonical Wnt signaling pathway regulates several processes during larval development; however, few target genes of this pathway have been identified. To address this deficit, we used a novel approach of conditionally activated Wnt signaling during a defined stage of larval life by overexpressing an activated beta-catenin protein, then used microarray analysis to identify genes showing altered expression compared with control animals. We identified 166 differentially expressed genes, of which 104 were up-regulated. A subset of the up-regulated genes was shown to have altered expression in mutants with decreased or increased Wnt signaling; we consider these genes to be bona fide C. elegans Wnt pathway targets. Among these was a group of six genes, including the cuticular collagen genes, bli-1 col-38, col-49, and col-71. These genes show a peak of expression in the mid L4 stage during normal development, suggesting a role in adult cuticle formation. Consistent with this finding, reduction of function for several of the genes causes phenotypes suggestive of defects in cuticle function or integrity. Therefore, this work has identified a large number of putative Wnt pathway target genes during larval life, including a small subset of Wnt-regulated collagen genes that may function in synthesis of the adult cuticle.

Larvae of the genus Eleodes (Coleoptera, Tenebrionidae): matrix-based descriptions, cladistic analysis, and key to late instars

PubMed Central

Smith, Aaron D.; Dornburg, Rebecca; Wheeler, Quentin D.

2014-01-01

Abstract Darkling beetle larvae (Coleoptera, Tenebrionidae) are collectively referred to as false wireworms. Larvae from several species in the genus Eleodes are considered to be agricultural pests, though relatively little work has been done to associate larvae with adults of the same species and only a handful of species have been characterized in their larval state. Morphological characters from late instar larvae were examined and coded to produce a matrix in the server-based content management system mx. The resulting morphology matrix was used to produce larval species descriptions, reconstruct a phylogeny, and build a key to the species included in the matrix. Larvae are described for the first time for the following 12 species: Eleodes anthracinus Blaisdell, Eleodes carbonarius (Say), Eleodes caudiferus LeConte, Eleodes extricatus (Say), Eleodes goryi Solier, Eleodes hispilabris (Say), Eleodes nigropilosus LeConte, Eleodes pilosus Horn, Eleodes subnitens LeConte, Eleodes tenuipes Casey, Eleodes tribulus Thomas, and Eleodes wheeleri Aalbu, Smith & Triplehorn. The larval stage of Eleodes armatus LeConte is redescribed with additional characters to differentiate it from the newly described congeneric larvae. PMID:25009429

Temperature effects on egg development and larval condition in the lesser sandeel, Ammodytes marinus

NASA Astrophysics Data System (ADS)

Régnier, Thomas; Gibb, Fiona M.; Wright, Peter J.

2018-04-01

Understanding the influence of temperature on egg development and larval condition in planktonic fish is a prerequisite to understanding the phenological impacts of climate change on marine food-webs. The lesser sandeel, Ammodytes marinus (Raitt 1934), is a key trophic link between zooplankton and many piscivorous fish, sea birds and mammals in the northeast Atlantic. Temperature-egg development relationships were determined for batches of lesser sandeel eggs. Hatching began as early as 19 days post fertilisation at 11 °C and as late as 36 days post fertilisation at 6 °C, which is faster than egg development rates reported for closely related species at the lower end of the tested temperature range. The average size of newly hatched larvae decreased with increasing incubation temperatures in early hatching larvae, but this effect was lost by the middle of the hatching period. While the study revealed important temperature effects on egg development rate, predicted variability based on the range of temperatures eggs experience in the field, suggests it is only a minor contributor to the observed inter-annual variation in hatch date.

Cellular Apoptosis of Hemocytes from Dendrolimus tabulaeformis Tsai et Liu Larvae Induced with the Secondary Metabolites of Beauveria brongniartii (Sacc.) Petch

PubMed Central

Fan, Jinhua; Xie, Yingping; Xue, Jiaoliang; Zhang, Yingling; Yang, Qian

2013-01-01

To investigate the effect of the secondary metabolites of entomopathogenic fungus on the hemocyte immunity of host insect, the secondary metabolite complex (SMC) of Beauveria brongniartii was used in three concentrations (5.5, 55, and 550 µg/mL), and the 4th instar larvae of the pine caterpillar Dendrolimus tabulaeformis were employed as host insects. The larvae were inoculated with the SMC solutions by injection in bioassays. Apoptosis of the larval hemocytes was observed using fluorescence microscopy (FM), transmission electron microscopy (TEM), and flow cytometry (FCM). The FM results showed that in the treated groups, larval hemocytes exhibited symptoms of early apoptosis at 6 h post-treatment by radiating a non-uniform kelly fluorescence and exhibited symptoms of late apoptosis at 12 h post-treatment by radiating a non-uniform orange fluorescence. Under TEM, the following ultra-structural changes associated with apoptosis of the larval hemocytes were observed in the treated groups: the nuclei were hypertrophied, slight folds were on the nuclear envelope, the chromatin became concentrated, the mitochondrial cristae disappeared or were disorderly, most cells developed blebs, and fibrillar aggregation appeared and accumulated in the cytoplasm. Apoptosis of the larval hemocytes was detected by FCM at 6 h post-treatment; the percentage of early apoptotic cells in the SMC 5.5, 55, and 550 µg/mL treatment groups were 11.93%, 13.10%, and 18.42%, respectively. Late apoptosis first occurred at 12 h post-treatment; the highest rate of apoptosis was 36.54 ± 4.37% at 24 h post-treatment in the SMC 55 µg/mL treatment group. In general, the cellular apoptosis rate was positively correlated with the SMC concentration and the time post-treatment. These results indicate that secondary metabolites of B . brongniartii are able to attack the hemocytes of D . tabulaeformis larvae and induce cellular apoptosis, thereby providing new evidence that secondary metabolites of mycopathogens can act on host immune systems. PMID:23940771

First Record of the Larval Endoparasitoid Tachinaephagus zealandicus (Hymenoptera: Encyrtidae) From Fly Hosts Developing on Burnt Remains and in Pennsylvania.

PubMed

Rivers, David B

2016-05-01

Adults of the gregarious larval endoparasitoid Tachinaephagus zealandicus Ashmead (Hymenoptera: Encyrtidae) were collected from two species of carrion-inhabiting flies, Phormia regina Meigen (Diptera: Calliphoridae) and Hydrotaea aenescens Wiedemann (Muscidae), associated with the burnt remains of a domesticated pig, Sus scrofa L. (Artiodactyla: Suidae), during late summer in south central Pennsylvania. This represents the first reported occurrence of the wasp in the state and only the second in the mid-Atlantic region. Collection from P. regina is a new host record for T. zealandicus and also the first for this parasitoid being attracted to flies on burnt remains. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Magnetic Resonance Imaging of Alimentary Tract Development in Manduca sexta

PubMed Central

Rowland, Ian J.; Goodman, Walter G.

2016-01-01

Non-invasive 3D magnetic resonance imaging techniques were used to investigate metamorphosis of the alimentary tract of Manduca sexta from the larval to the adult stage. The larval midgut contracts in volume immediately following cessation of feeding and then greatly enlarges during the late pharate pupal period. Magnetic resonance imaging revealed that the foregut and hindgut of the pharate pupa undergo ecdysis considerably earlier than the external exoskeleton. Expansion of air sacs in the early pupa and development of flight muscles several days later appear to orient the midgut into its adult position in the abdomen. The crop, an adult auxiliary storage organ, begins development as a dorsal outgrowth of the foregut. This coincides with a reported increase in pupal ecdysteroid titers. An outgrowth of the hindgut, the rectal sac, appears several days later and continues to expand until it nearly fills the dorsal half of the abdominal cavity. This development correlates with a second rise in pupal ecdysteroid titers. In the pharate pupa, the presence of paramagnetic species renders the silk glands hyperintense. PMID:27280776

Can metamorphosis survival during larval development in spiny lobster Sagmariasus verreauxi be improved through quantitative genetic inheritance?

PubMed

Nguyen, Nguyen H; Fitzgibbon, Quinn P; Quinn, Jane; Smith, Greg; Battaglene, Stephen; Knibb, Wayne

2018-05-04

One of the major impediments to spiny lobster aquaculture is the high cost of hatchery production due to the long and complex larval cycle and poor survival during the many moult stages, especially at metamorphosis. We examined if the key trait of larval survival can be improved through selection by determining if genetic variance exists for this trait. Specifically, we report, for the first time, genetic parameters (heritability and correlations) for early survival rates recorded at five larval phases; early-phyllosoma stages (instars 1-6; S1), mid-phyllosoma stages (instars; 7-12; S2), late-phyllosoma stages (instars 13-17; S3), metamorphosis (S4) and puerulus stage (S5) in hatchery-reared spiny lobster Sagmariasus verreauxi. The data were collected from a total of 235,060 larvae produced from 18 sires and 30 dams over nine years (2006 to 2014). Parentage of the offspring and full-sib families was verified using ten microsatellite markers. Analysis of variance components showed that the estimates of heritability for all the five phases of larval survival obtained from linear mixed model were generally similar to those obtained from threshold logistic generalised models (0.03-0.47 vs. 0.01-0.50). The heritability estimates for survival traits recorded in the early larval phases (S1 and S2) were higher than those estimated in later phases (S3, S4 and S5). The existence of the additive genetic component in larval survival traits indicate that they could be improved through selection. Both phenotypic and genetic correlations among the five survival measures studied were moderate to high and positive. The genetic associations between successive rearing periods were stronger than those that are further apart. Our estimates of heritability and genetic correlations reported here in a spiny lobster species indicate that improvement in the early survival especially during metamorphosis can be achieved through genetic selection in this highly economic value species.

Larval feeding behavior and ant association in frosted elfin, Callophrys irus (Lycaenidae)

USGS Publications Warehouse

Albanese, G.; Nelson, M.W.; Vickery, P.D.; Sievert, P.R.

2007-01-01

Callophrys irus is a rare and declining lycaenid found in the eastern U.S., inhabiting xeric and open habitats maintained by disturbance. Populations are localized and monophagous. We document a previously undescribed larval feeding behavior in both field and lab reared larvae in which late instar larvae girdled the main stem of the host plant. Girdled stems provide a unique feeding sign that was useful in detecting the presence of larvae in the field. We also observed frequent association of field larvae with several species of ants and provide a list of ant species. We suggest two hypotheses on the potential benefits of stem-girdling to C. irus larvae: 1) Stem girdling provides phloem sap as a larval food source and increases the leaf nutrient concentration, increasing larval growth rates and providing high quality honeydew for attending ants; 2) Stem girdling reduces stem toxicity by inhibiting transport of toxins from roots to the stem.

The Role of Maternal Nutrition on Oocyte Size and Quality, with Respect to Early Larval Development in The Coral-Eating Starfish, Acanthaster planci.

PubMed

Caballes, Ciemon Frank; Pratchett, Morgan S; Kerr, Alexander M; Rivera-Posada, Jairo A

2016-01-01

Variation in local environmental conditions can have pronounced effects on the population structure and dynamics of marine organisms. Previous studies on crown-of-thorns starfish, Acanthaster planci, have primarily focused on effects of water quality and nutrient availability on larval growth and survival, while the role of maternal nutrition on reproduction and larval development has been overlooked. To examine the effects of maternal nutrition on oocyte size and early larval development in A. planci, we pre-conditioned females for 60 days on alternative diets of preferred coral prey (Acropora abrotanoides) versus non-preferred coral prey (Porites rus) and compared resulting gametes and progeny to those produced by females that were starved over the same period. Females fed ad libitum with Acropora increased in weight, produced heavier gonads and produced larger oocytes compared to Porites-fed and starved females. Fed starfish (regardless of whether it was Acropora or Porites) produced bigger larvae with larger stomachs and had a higher frequency of normal larvae that reached the late bipinnaria / early brachiolaria stage compared to starved starfish. Females on Acropora diet also produced a higher proportion of larvae that progressed to more advanced stages faster compared to Porites-fed starfish, which progressed faster than starved starfish. These results suggest that maternal provisioning can have important consequences for the quality and quantity of progeny. Because food quality (coral community structure) and quantity (coral abundance) varies widely among reef locations and habitats, local variation in maternal nutrition of A. planci is likely to moderate reproductive success and may explain temporal and spatial fluctuations in abundance of this species.

The Role of Maternal Nutrition on Oocyte Size and Quality, with Respect to Early Larval Development in The Coral-Eating Starfish, Acanthaster planci

PubMed Central

Pratchett, Morgan S.; Kerr, Alexander M.; Rivera-Posada, Jairo A.

2016-01-01

Variation in local environmental conditions can have pronounced effects on the population structure and dynamics of marine organisms. Previous studies on crown-of-thorns starfish, Acanthaster planci, have primarily focused on effects of water quality and nutrient availability on larval growth and survival, while the role of maternal nutrition on reproduction and larval development has been overlooked. To examine the effects of maternal nutrition on oocyte size and early larval development in A. planci, we pre-conditioned females for 60 days on alternative diets of preferred coral prey (Acropora abrotanoides) versus non-preferred coral prey (Porites rus) and compared resulting gametes and progeny to those produced by females that were starved over the same period. Females fed ad libitum with Acropora increased in weight, produced heavier gonads and produced larger oocytes compared to Porites-fed and starved females. Fed starfish (regardless of whether it was Acropora or Porites) produced bigger larvae with larger stomachs and had a higher frequency of normal larvae that reached the late bipinnaria / early brachiolaria stage compared to starved starfish. Females on Acropora diet also produced a higher proportion of larvae that progressed to more advanced stages faster compared to Porites-fed starfish, which progressed faster than starved starfish. These results suggest that maternal provisioning can have important consequences for the quality and quantity of progeny. Because food quality (coral community structure) and quantity (coral abundance) varies widely among reef locations and habitats, local variation in maternal nutrition of A. planci is likely to moderate reproductive success and may explain temporal and spatial fluctuations in abundance of this species. PMID:27327627

Biogenesis of Golgi Stacks in Imaginal Discs of Drosophila melanogaster

PubMed Central

Kondylis, Vangelis; Goulding, Sarah E.; Dunne, Jonathan C.; Rabouille, Catherine

2001-01-01

We provide a detailed description of Golgi stack biogenesis that takes place in vivo during one of the morphogenetic events in the lifespan of Drosophila melanogaster. In early third-instar larvae, small clusters consisting mostly of vesicles and tubules were present in epithelial imaginal disk cells. As larvae progressed through mid- and late-third instar, these larval clusters became larger but also increasingly formed cisternae, some of which were stacked. In white pupae, the typical Golgi stack was observed. We show that larval clusters are Golgi stack precursors by 1) localizing various Golgi-specific markers to the larval clusters by electron and immunofluorescence confocal microscopy, 2) driving this conversion in wild-type larvae incubated at 37°C for 2 h, and 3) showing that this conversion does not take place in an NSF1 mutant (comt 17). The biological significance of this conversion became clear when we found that the steroid hormone 20-hydroxyecdysone (ecdysone) is critically involved in this conversion. In its absence, Golgi stack biogenesis did not occur and the larval clusters remained unaltered. We showed that dGM130 and sec23p expression increases approximately three- and fivefold, respectively, when discs are exposed to ecdysone in vivo and in vitro. Taken together, these results suggest that we have developed an in vivo system to study the ecdysone-triggered Golgi stack biogenesis. PMID:11514618

Effects of MON810 Bt field corn on adult emergence of Helicoverpa zea (Lepidoptera: Noctuidae).

PubMed

Horner, T A; Dively, G P; Herbert, D A

2003-06-01

A 3-yr study (1996-1998) was conducted to evaluate the effects of MON810 Bt corn on Helicoverpa zea (Boddie) emergence and to determine whether delayed larval development as a result of Bt intoxication results in higher levels of diapause induction and pupal mortality. In the 1997 study, there was no difference in prepupal mortality between corn types, although significantly more prepupae from Bt plots than from non-Bt plots died in emergence buckets before constructing pupal chambers in 1998. In all years, significantly fewer moths emerged from prepupae collected from Bt plots, suggesting that effects of the expressed Cry1Ab extended to the prepupal and pupal stages. Late plantings of corn showed the greatest reductions in moth emergence from Bt corn because environmental conditions were more conducive to trigger diapause at the time H. zea was developing in these plantings. This was supported by a significantly greater proportion of diapausing pupae remaining in the ground in the late plantings of both Bt and non-Bt corn. For April and early May plantings, larval feeding on Bt corn delayed the time to pupation, although there was no significant difference in moth emergence between corn types for those larvae that successfully pupated. Although Bt expression had less impact on the proportion of moths emerging, the actual number of moths emerging from Bt corn was significantly reduced because fewer larvae reached pupation. Delays in adult emergence, along with significant reductions in adult emergence from MON810 Bt corn, should reduce the rates of colonization in soybean and other late host crops but may also result in asynchrony of mating between individuals emerging from Bt and non-Bt corn. This, in turn, may contribute to the evolution of resistance to Bt corn.

Competition between larvae in a butterfly Pieris napi and maintenance of different life-history strategies.

PubMed

Kivelä, Sami M; Välimäki, Panu

2008-05-01

1. In scramble competition all individuals suffer equally from competition, whereas in contest competition some individuals outperform the others. Generally, larger individuals gain asymmetric advantage in competition over smaller ones. Given the positive correlation between age and size, asynchronous birth may result in asymmetric competition among juveniles. 2. In Pieris napi (Lepidoptera: Pieridae), reproductive rate is determined by the females' intrinsic mating tactic. The early reproductive rate is high in females with a low mating frequency and low in females with a high mating frequency, whereas lifetime fecundity shows the opposite pattern. Thus, offspring of monandrous females start to develop in relatively low densities and they are relatively large when the offspring of highly polyandrous females start to hatch. 3. The purpose of this study was to explore if asymmetry in larval competition could outweigh the late-life benefits of polyandry. In a laboratory experiment, P. napi larvae of different ages were reared together in different densities. 4. Increasing density decreased both larval survival and reachable pupal mass, but had no effect on duration of larval period. Younger larvae suffered from high mortality and reduced size compared with the older larvae. Mortality decreased in the older cohort with increasing age difference between the cohorts, and the reverse occurred in the younger cohort. Increasing age difference between the cohorts was associated with increase in pupal mass in both cohorts. All the variables showed a lot of variation between broods of different females. 5. The results suggest that polyandrous females, or more generally females with a low early reproductive rate, may lose a great proportion of their late-life benefits, which may partly explain the maintenance of polymorphism in reproductive strategies within species.

Tyrosine pathway regulation is host-mediated in the pea aphid symbiosis during late embryonic and early larval development.

PubMed

Rabatel, Andréane; Febvay, Gérard; Gaget, Karen; Duport, Gabrielle; Baa-Puyoulet, Patrice; Sapountzis, Panagiotis; Bendridi, Nadia; Rey, Marjolaine; Rahbé, Yvan; Charles, Hubert; Calevro, Federica; Colella, Stefano

2013-04-10

Nutritional symbioses play a central role in insects' adaptation to specialized diets and in their evolutionary success. The obligatory symbiosis between the pea aphid, Acyrthosiphon pisum, and the bacterium, Buchnera aphidicola, is no exception as it enables this important agricultural pest insect to develop on a diet exclusively based on plant phloem sap. The symbiotic bacteria provide the host with essential amino acids lacking in its diet but necessary for the rapid embryonic growth seen in the parthenogenetic viviparous reproduction of aphids. The aphid furnishes, in exchange, non-essential amino acids and other important metabolites. Understanding the regulations acting on this integrated metabolic system during the development of this insect is essential in elucidating aphid biology. We used a microarray-based approach to analyse gene expression in the late embryonic and the early larval stages of the pea aphid, characterizing, for the first time, the transcriptional profiles in these developmental phases. Our analyses allowed us to identify key genes in the phenylalanine, tyrosine and dopamine pathways and we identified ACYPI004243, one of the four genes encoding for the aspartate transaminase (E.C. 2.6.1.1), as specifically regulated during development. Indeed, the tyrosine biosynthetic pathway is crucial for the symbiotic metabolism as it is shared between the two partners, all the precursors being produced by B. aphidicola. Our microarray data are supported by HPLC amino acid analyses demonstrating an accumulation of tyrosine at the same developmental stages, with an up-regulation of the tyrosine biosynthetic genes. Tyrosine is also essential for the synthesis of cuticular proteins and it is an important precursor for cuticle maturation: together with the up-regulation of tyrosine biosynthesis, we observed an up-regulation of cuticular genes expression. We were also able to identify some amino acid transporter genes which are essential for the switch over to the late embryonic stages in pea aphid development. Our data show that, in the development of A. pisum, a specific host gene set regulates the biosynthetic pathways of amino acids, demonstrating how the regulation of gene expression enables an insect to control the production of metabolites crucial for its own development and symbiotic metabolism.

Caffeine induces high expression of cyp-35A family genes and inhibits the early larval development in Caenorhabditis elegans.

PubMed

Min, Hyemin; Kawasaki, Ichiro; Gong, Joomi; Shim, Yhong-Hee

2015-03-01

Intake of caffeine during pregnancy can cause retardation of fetal development. Although the significant influence of caffeine on animal development is widely recognized, much remains unknown about its mode of action because of its pleiotropic effects on living organisms. In the present study, by using Caenorhabditis elegans as a model organism, the effects of caffeine on development were examined. Brood size, embryonic lethality, and percent larval development were investigated, and caffeine was found to inhibit the development of C. elegans at most of the stages in a dosage-dependent fashion. Upon treatment with 30 mM caffeine, the majority (86.1 ± 3.4%) of the L1 larvae were irreversibly arrested without further development. In contrast, many of the late-stage larvae survived and grew to adults when exposed to the same 30 mM caffeine. These results suggest that early-stage larvae are more susceptible to caffeine than later-stage larvae. To understand the metabolic responses to caffeine treatment, the levels of expression of cytochrome P450 (cyp) genes were examined with or without caffeine treatment using comparative micro-array, and it was found that the expression of 24 cyp genes was increased by more than 2-fold (p < 0.05). Among them, induction of the cyp-35A gene family was the most prominent. Interestingly, depletion of the cyp-35A family genes one-by-one or in combination through RNA interference resulted in partial rescue from early larval developmental arrest caused by caffeine treatment, suggesting that the high-level induction of cyp-35A family genes can be fatal to the development of early-stage larvae.

Impact of small mammal predators on gypsy moth

Treesearch

Joseph S. Elkinton; Harvey R. Smith; Andrew M. Liebhold

1991-01-01

Research in western Massachusetts, on Cape Cod, and on Bryant Mountain in Vermont conducted over the past decade has confirmed the importance of mortality during the late larval and pupal stages to gypsy moth population dynamics.

Endocrine Control of Exaggerated Trait Growth in Rhinoceros Beetles.

PubMed

Zinna, R; Gotoh, H; Brent, C S; Dolezal, A; Kraus, A; Niimi, T; Emlen, D; Lavine, L C

2016-08-01

Juvenile hormone (JH) is a key insect growth regulator frequently involved in modulating phenotypically plastic traits such as caste determination in eusocial species, wing polymorphisms in aphids, and mandible size in stag beetles. The jaw morphology of stag beetles is sexually-dimorphic and condition-dependent; males have larger jaws than females and those developing under optimum conditions are larger in overall body size and have disproportionately larger jaws than males raised under poor conditions. We have previously shown that large males have higher JH titers than small males during development, and ectopic application of fenoxycarb (JH analog) to small males can induce mandibular growth similar to that of larger males. What remains unknown is whether JH regulates condition-dependent trait growth in other insects with extreme sexually selected structures. In this study, we tested the hypothesis that JH mediates the condition-dependent expression of the elaborate horns of the Asian rhinoceros beetle, Trypoxylus dichotomus. The sexually dimorphic head horn of this beetle is sensitive to nutritional state during larval development. Like stag beetles, male rhinoceros beetles receiving copious food produce disproportionately large horns for their body size compared with males under restricted diets. We show that JH titers are correlated with body size during the late feeding and early prepupal periods, but this correlation disappears by the late prepupal period, the period of maximum horn growth. While ectopic application of fenoxycarb during the third larval instar significantly delayed pupation, it had no effect on adult horn size relative to body size. Fenoxycarb application to late prepupae also had at most a marginal effect on relative horn size. We discuss our results in context of other endocrine signals of condition-dependent trait exaggeration and suggest that different beetle lineages may have co-opted different physiological signaling mechanisms to achieve heightened nutrient-sensitive weapon growth. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Knockout silkworms reveal a dispensable role for juvenile hormones in holometabolous life cycle

PubMed Central

Daimon, Takaaki; Uchibori, Miwa; Nakao, Hajime; Sezutsu, Hideki; Shinoda, Tetsuro

2015-01-01

Insect juvenile hormones (JHs) prevent precocious metamorphosis and allow larvae to undergo multiple rounds of status quo molts. However, the roles of JHs during the embryonic and very early larval stages have not been fully understood. We generated and characterized knockout silkworms (Bombyx mori) with null mutations in JH biosynthesis or JH receptor genes using genome-editing tools. We found that embryonic growth and morphogenesis are largely independent of JHs in Bombyx and that, even in the absence of JHs or JH signaling, pupal characters are not formed in first- or second-instar larvae, and precocious metamorphosis is induced after the second instar at the earliest. We also show by mosaic analysis that a pupal specifier gene broad, which is dramatically up-regulated in the late stage of the last larval instar, is essential for pupal commitment in the epidermis. Importantly, the mRNA expression level of broad, which is thought to be repressed by JHs, remained at very low basal levels during the early larval instars of JH-deficient or JH signaling-deficient knockouts. Therefore, our study suggests that the long-accepted paradigm that JHs maintain the juvenile status throughout larval life should be revised because the larval status can be maintained by a JH-independent mechanism in very early larval instars. We propose that the lack of competence for metamorphosis during the early larval stages may result from the absence of an unidentified broad-inducing factor, i.e., a competence factor. PMID:26195792

Knockout silkworms reveal a dispensable role for juvenile hormones in holometabolous life cycle.

PubMed

Daimon, Takaaki; Uchibori, Miwa; Nakao, Hajime; Sezutsu, Hideki; Shinoda, Tetsuro

2015-08-04

Insect juvenile hormones (JHs) prevent precocious metamorphosis and allow larvae to undergo multiple rounds of status quo molts. However, the roles of JHs during the embryonic and very early larval stages have not been fully understood. We generated and characterized knockout silkworms (Bombyx mori) with null mutations in JH biosynthesis or JH receptor genes using genome-editing tools. We found that embryonic growth and morphogenesis are largely independent of JHs in Bombyx and that, even in the absence of JHs or JH signaling, pupal characters are not formed in first- or second-instar larvae, and precocious metamorphosis is induced after the second instar at the earliest. We also show by mosaic analysis that a pupal specifier gene broad, which is dramatically up-regulated in the late stage of the last larval instar, is essential for pupal commitment in the epidermis. Importantly, the mRNA expression level of broad, which is thought to be repressed by JHs, remained at very low basal levels during the early larval instars of JH-deficient or JH signaling-deficient knockouts. Therefore, our study suggests that the long-accepted paradigm that JHs maintain the juvenile status throughout larval life should be revised because the larval status can be maintained by a JH-independent mechanism in very early larval instars. We propose that the lack of competence for metamorphosis during the early larval stages may result from the absence of an unidentified broad-inducing factor, i.e., a competence factor.

Evaluation of the naturally-derived insecticide spinosad against Culex pipiens L. (Diptera: Culicidae) larvae in septic tank water in Antalya, Turkey.

PubMed

Cetin, Huseyin; Yanikoglu, Atila; Cilek, James E

2005-06-01

The naturally-derived insecticide spinosad (Conserve SC) was evaluated against larval Culex pipiens L. (Diptera: Culicidae) under laboratory and field conditions in Antalya, Turkey. Laboratory bioassays showed that the 24 h LC50 and LC90 against late 3rd and early 4th instars were estimated at 0.027 and 0.111 parts per million, respectively, while adult emergence was eliminated at concentrations above 0.06 ppm. Larval mortality from septic tanks that were treated with spinosad at rates of 25, 50, 100, and 200 g ai/ha ranged between 22 to 78% 1 day after application. At 7 days post-treatment, larval mortality ranged from 2 to 50% and at 14 days mortality was <10% for all treatments. Larval bioassays of the water from those septic tanks treated at 100 and 200 g ai/ha resulted in an elimination of Cx. pipiens larvae 7 days after treatment. After this time, larval reduction declined to 79 and 83%, respectively, 14 days after treatment. Larval reduction in septic tanks treated at the two lowest rates (i.e. 25 and 50 g ai/ha) ranged from 14 to 74% during the 14-day study. These results indicated that spinosad can be considered an effective larvicide for treatment of septic tanks against Cx. pipiens.

Larval salinity tolerance of the South American salt-marsh crab, Neohelice (Chasmagnathus) granulata: physiological constraints to estuarine retention, export and reimmigration

NASA Astrophysics Data System (ADS)

Anger, Klaus; Spivak, Eduardo; Luppi, Tomás; Bas, Claudia; Ismael, Deborah

2008-06-01

The semiterrestrial crab Neohelice (= Chasmagnathus) granulata (Dana 1851) is a predominant species in brackish salt marshes, mangroves and estuaries. Its larvae are exported towards coastal marine waters. In order to estimate the limits of salinity tolerance constraining larval retention in estuarine habitats, we exposed in laboratory experiments freshly hatched zoeae to six different salinities (5 32‰). At 5‰, the larvae survived for a maximum of 2 weeks, reaching only exceptionally the second zoeal stage, while 38% survived to the megalopa stage at 10‰. Shortest development and negligible mortality occurred at all higher salt concentrations. These observations show that the larvae of N. granulata can tolerate a retention in the mesohaline reaches of estuaries, with a lower limit of ca. 10 15‰. Maximum survival at 25‰ suggests that polyhaline conditions rather than an export to oceanic waters are optimal for successful larval development of this species. In another experiment, we tested the capability of the last zoeal stage (IV) for reimmigration from coastal marine into brackish waters. Stepwise reductions of salinity during this stage allowed for moulting to the megalopa at 4 10‰. Although survival was at these conditions reduced and development delayed, these results suggest that already the zoea-IV stage is able to initiate the reimmigration into estuaries. After further salinity reduction, megalopae survived in this experiment for up to >3 weeks in freshwater, without moulting to juvenile crabs. In a similar experiment starting from the megalopa stage, successful metamorphosis occurred at 4 10‰, and juvenile growth continued in freshwater. Although these juvenile crabs showed significantly enhanced mortality and smaller carapace width compared to a seawater control, our results show that the late larval and early juvenile stages of N. granulata are well adapted for successful recruitment in brackish and even limnetic habitats.

A novel interplay between the ubiquitin–proteasome system and serine proteases during Drosophila development.

PubMed

Lipinszki, Zoltán; Klement, Eva; Hunyadi-Gulyas, Eva; Medzihradszky, Katalin F; Márkus, Róbert; Pál, Margit; Deák, Péter; Udvardy, Andor

2013-09-15

The concentrations of the Drosophila proteasomal and extraproteasomal polyubiquitin receptors fluctuate in a developmentally regulated fashion. This fluctuation is generated by a previously unidentified proteolytic activity. In the present paper, we describe the purification, identification and characterization of this protease (endoproteinase I). Its expression increases sharply at the L1-L2 larval stages, remains high until the second half of the L3 stage, then declines dramatically. This sharp decrease coincides precisely with the increase of polyubiquitin receptor concentrations in late L3 larvae, which suggests a tight developmental co-regulation. RNAi-induced down-regulation of endoproteinase I results in pupal lethality. Interestingly, we found a cross-talk between the 26S proteasome and this larval protease: transgenic overexpression of the in vivo target of endoproteinase I, the C-terminal half of the proteasomal polyubiquitin receptor subunit p54/Rpn10 results in transcriptional down-regulation of endoproteinase I and consequently a lower level of proteolytic elimination of the polyubiquitin receptors. Another larval protease, Jonah65A-IV, which degrades only unfolded proteins and exhibits similar cross-talk with the proteasome has also been purified and characterized. It may prevent the accumulation of polyubiquitylated proteins in larvae contrary to the low polyubiquitin receptor concentration.

Habitat use by larval fishes in backwater lake of the upper Mississippi River

USGS Publications Warehouse

Dewey, M.R.; Jennings, C.A.

1992-01-01

Light traps were used to sample larval fishes in Lawrence Lake (Pool 8, upper Mississippi River) from late May through mid-August 1990. Catches differed considerably between vegetated sites and an adjacent open- water area and were highly variable among vegetated stations. Sunfishes (Lepomis spp.) dominated the vegetated sites. Brook silversides (Labidesthes sicculus), Cyprinidae ad gizzard shad (Dorosoma cepedianum) dominated catches at the open-water site. There was no difference in fish use of vegetated habitats near and far from the main channel of the Mississippi River. Taxonomic diversity was greatest at stations with emergent vegetation.

Correlated evolution between mode of larval development and habitat in muricid gastropods.

PubMed

Pappalardo, Paula; Rodríguez-Serrano, Enrique; Fernández, Miriam

2014-01-01

Larval modes of development affect evolutionary processes and influence the distribution of marine invertebrates in the ocean. The decrease in pelagic development toward higher latitudes is one of the patterns of distribution most frequently discussed in marine organisms (Thorson's rule), which has been related to increased larval mortality associated with long pelagic durations in colder waters. However, the type of substrate occupied by adults has been suggested to influence the generality of the latitudinal patterns in larval development. To help understand how the environment affects the evolution of larval types we evaluated the association between larval development and habitat using gastropods of the Muricidae family as a model group. To achieve this goal, we collected information on latitudinal distribution, sea water temperature, larval development and type of substrate occupied by adults. We constructed a molecular phylogeny for 45 species of muricids to estimate the ancestral character states and to assess the relationship between traits using comparative methods in a Bayesian framework. Our results showed high probability for a common ancestor of the muricids with nonpelagic (and nonfeeding) development, that lived in hard bottoms and cold temperatures. From this ancestor, a pelagic feeding larva evolved three times, and some species shifted to warmer temperatures or sand bottoms. The evolution of larval development was not independent of habitat; the most probable evolutionary route reconstructed in the analysis of correlated evolution showed that type of larval development may change in soft bottoms but in hard bottoms this change is highly unlikely. Lower sea water temperatures were associated with nonpelagic modes of development, supporting Thorson's rule. We show how environmental pressures can favor a particular mode of larval development or transitions between larval modes and discuss the reacquisition of feeding larva in muricids gastropods.

Larval descriptions of the family Porcellanidae: A worldwide annotated compilation of the literature (Crustacea, Decapoda)

PubMed Central

Vela, María José; González-Gordillo, Juan Ignacio

2016-01-01

Abstract For most of the family Porcellanidae, which comprises 283 species, larval development remains to be described. Full development has been only described for 52 species, while part of the larval cycle has been described for 45 species. The importance of knowing the complete larval development of a species goes beyond allowing the identification of larval specimens collected in the plankton. Morphological larval data also constitute a support to cladistic techniques used in the establishment of the phylogenetic status (see Hiller et al. 2006, Marco-Herrero et al. 2013). Nevertheless, the literature on the larval development of this family is old and widely dispersed and in many cases it is difficult to collect the available information on a particular taxon. Towards the aim of facilitating future research, all information available on the larval development of porcellanids has been compiled. Following the taxonomic checklist of Porcellanidae proposed by Osawa and McLaughlin (2010), a checklist has been prepared that reflects the current knowledge about larval development of the group including larval stages and the method used to obtain the larvae, together with references. Those species for which the recognised names have been changed according to Osawa and McLaughlin (2010) are indicated. PMID:27081332

Survival dynamics of scleractinian coral larvae and implications for dispersal

NASA Astrophysics Data System (ADS)

Graham, E. M.; Baird, A. H.; Connolly, S. R.

2008-09-01

Survival of pelagic marine larvae is an important determinant of dispersal potential. Despite this, few estimates of larval survival are available. For scleractinian corals, few studies of larval survival are long enough to provide accurate estimates of longevity. Moreover, changes in mortality rates during larval life, expected on theoretical grounds, have implications for the degree of connectivity among reefs and have not been quantified for any coral species. This study quantified the survival of larvae from five broadcast-spawning scleractinian corals ( Acropora latistella, Favia pallida, Pectinia paeonia, Goniastrea aspera, and Montastraea magnistellata) to estimate larval longevity, and to test for changes in mortality rates as larvae age. Maximum lifespans ranged from 195 to 244 d. These longevities substantially exceed those documented previously for coral larvae that lack zooxanthellae, and they exceed predictions based on metabolic rates prevailing early in larval life. In addition, larval mortality rates exhibited strong patterns of variation throughout the larval stage. Three periods were identified in four species: high initial rates of mortality; followed by a low, approximately constant rate of mortality; and finally, progressively increasing mortality after approximately 100 d. The lifetimes observed in this study suggest that the potential for long-distance dispersal may be substantially greater than previously thought. Indeed, detection of increasing mortality rates late in life suggests that energy reserves do not reach critically low levels until approximately 100 d after spawning. Conversely, increased mortality rates early in life decrease the likelihood that larvae transported away from their natal reef will survive to reach nearby reefs, and thus decrease connectivity at regional scales. These results show how variation in larval survivorship with age may help to explain the seeming paradox of high genetic structure at metapopulation scales, coupled with the maintenance of extensive geographic ranges observed in many coral species.

Changes during late-stage embryonic development from egg-juvenile to free-living hatchling in Chinese freshwater crab Sinopotamon yangtsekiense (Decapoda, Brachyura, Potamidae)

NASA Astrophysics Data System (ADS)

Xue, Junzeng; Liu, Yan; Cumberlidge, Neil; Wu, Huixian

2013-05-01

This study expands on recent reports that direct development in the Chinese potamid freshwater crab Sinopotamon yangtsekiense involves the completion of all brachyuran larval stages (nauplius, zoea, and megalopa) inside the egg case during embryonic development. Detailed studies of embryonic development in this species revealed the presence of an additional larval stage (the egg-juvenile) between the megalopa and the free-living hatchling crab. We described and compared the appendages of the head, thorax, and abdomen of the egg-juvenile with those of the hatchling crab in S. yangtsekiense. Significant differences were found between most of the appendages of these two stages with a soft exoskeleton in the egg-juvenile, no joint articulation, a slimmer appearance, and a lack of setae when compared with the newly emerged free-living hatchling crab. These modifications of the appendages are related to the confinement within the egg case of the egg-megalopa and egg-juvenile during direct development, and the need for the free-living hatchling freshwater crab to move, feed, and respire. In marine crabs, the megalopa gives rise to the first crab stage whereas in freshwater crabs the egg-juvenile follows the megalopa and immediately precedes the free-living first crab stage.

Life-History Traits of Spodoptera frugiperda Populations Exposed to Low-Dose Bt Maize

PubMed Central

Sousa, Fernanda F.; Mendes, Simone M.; Santos-Amaya, Oscar F.; Araújo, Octávio G.; Oliveira, Eugenio E.

2016-01-01

Exposure to Bacillus thuringiensis (Bt) toxins in low- and moderate-dose transgenic crops may induce sublethal effects and increase the rate of Bt resistance evolution, potentially compromising control efficacy against target pests. We tested this hypothesis using the fall armyworm Spodoptera frugiperda, a major polyphagous lepidopteran pest relatively tolerant to Bt notorious for evolving field-relevant resistance to single-gene Bt maize. Late-instar larvae were collected from Bt Cry1Ab and non-Bt maize fields in five locations in Brazil, and their offspring was compared for survival, development, and population growth in rearing environment without and with Cry1Ab throughout larval development. Larval survival on Cry1Ab maize leaves varied from 20 to 80% among the populations. Larvae reared on Cry1Ab maize had seven-day delay in development time in relation to control larvae, and such delay was shorter in offspring of armyworms from Cry1Ab maize. Population growth rates were 50–70% lower for insects continuously exposed to Cry1Ab maize relative to controls, showing the population-level effect of Cry1Ab, which varied among the populations and prior exposure to Cry1Ab maize in the field. In three out of five populations, armyworms derived from Bt maize reared on Cry1Ab maize showed higher larval weight, faster larval development and better reproductive performance than the armyworms derived from non-Bt maize, and one of these populations showed better performance on both Cry1Ab and control diets, indicating no fitness cost of the resistance trait. Altogether, these results indicate that offspring of armyworms that developed on field-grown, single-gene Bt Cry1Ab maize had reduced performance on Cry1Ab maize foliage in two populations studied, but in other three populations, these offspring had better overall performance on the Bt maize foliage than that of the armyworms from non-Bt maize fields, possibly because of Cry1Ab resistance alleles in these populations. Implications of these findings for resistance management of S. frugiperda in Bt crops are discussed. PMID:27243977

Life-History Traits of Spodoptera frugiperda Populations Exposed to Low-Dose Bt Maize.

PubMed

Sousa, Fernanda F; Mendes, Simone M; Santos-Amaya, Oscar F; Araújo, Octávio G; Oliveira, Eugenio E; Pereira, Eliseu J G

2016-01-01

Exposure to Bacillus thuringiensis (Bt) toxins in low- and moderate-dose transgenic crops may induce sublethal effects and increase the rate of Bt resistance evolution, potentially compromising control efficacy against target pests. We tested this hypothesis using the fall armyworm Spodoptera frugiperda, a major polyphagous lepidopteran pest relatively tolerant to Bt notorious for evolving field-relevant resistance to single-gene Bt maize. Late-instar larvae were collected from Bt Cry1Ab and non-Bt maize fields in five locations in Brazil, and their offspring was compared for survival, development, and population growth in rearing environment without and with Cry1Ab throughout larval development. Larval survival on Cry1Ab maize leaves varied from 20 to 80% among the populations. Larvae reared on Cry1Ab maize had seven-day delay in development time in relation to control larvae, and such delay was shorter in offspring of armyworms from Cry1Ab maize. Population growth rates were 50-70% lower for insects continuously exposed to Cry1Ab maize relative to controls, showing the population-level effect of Cry1Ab, which varied among the populations and prior exposure to Cry1Ab maize in the field. In three out of five populations, armyworms derived from Bt maize reared on Cry1Ab maize showed higher larval weight, faster larval development and better reproductive performance than the armyworms derived from non-Bt maize, and one of these populations showed better performance on both Cry1Ab and control diets, indicating no fitness cost of the resistance trait. Altogether, these results indicate that offspring of armyworms that developed on field-grown, single-gene Bt Cry1Ab maize had reduced performance on Cry1Ab maize foliage in two populations studied, but in other three populations, these offspring had better overall performance on the Bt maize foliage than that of the armyworms from non-Bt maize fields, possibly because of Cry1Ab resistance alleles in these populations. Implications of these findings for resistance management of S. frugiperda in Bt crops are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryo, H.; Yoo, M.A.; Fujikawa, K.

Somatic reversion of strains with the ivory (wi) allele, a mutation associated with a tandem duplication of a DNA sequence at the white locus, increased with the age of larvae at the time of X-irradiation as expected from the increase in the number of target cells. In contrast, two independently isolated strains with unstable w+ loci associated with insertion of transposable elements showed higher reversion frequencies after treatment with X rays or ethyl methanesulfonate (EMS) at early larval stages than at late stages. Nevertheless, both the wi strain and the two unstable w+ strains reverted at nearly equal rates aftermore » treatment with X rays or EMS at early larval stages. Possible similarity in hot spot structure for the high reversibility of the two types of mutations is discussed in relation to production of presumed mutator-type cofactors specific to the transposon-caused mutations at early larval stages.« less

Effect of bodily fluids from honey bee (Apis mellifera) larvae on growth and genome-wide transcriptional response of the causal agent of American Foulbrood disease (Paenibacillus larvae).

PubMed

De Smet, Lina; De Koker, Dieter; Hawley, Alyse K; Foster, Leonard J; De Vos, Paul; de Graaf, Dirk C

2014-01-01

Paenibacillus larvae, the causal agent of American Foulbrood disease (AFB), affects honey bee health worldwide. The present study investigates the effect of bodily fluids from honey bee larvae on growth velocity and transcription for this Gram-positive, endospore-forming bacterium. It was observed that larval fluids accelerate the growth and lead to higher bacterial densities during stationary phase. The genome-wide transcriptional response of in vitro cultures of P. larvae to larval fluids was studied by microarray technology. Early responses of P. larvae to larval fluids are characterized by a general down-regulation of oligopeptide and sugar transporter genes, as well as by amino acid and carbohydrate metabolic genes, among others. Late responses are dominated by general down-regulation of sporulation genes and up-regulation of phage-related genes. A theoretical mechanism of carbon catabolite repression is discussed.

In vitro development of Strongylus edentatus to the fourth larval stage with notes on Strongylus vulgaris and Strongylus equinus.

PubMed

Farrar, R G; Klei, T R

1985-08-01

Strongylus edentatus was successfully cultured in vitro to the fourth larval stage (L4). Some growth continued for periods of 40-50 days at which time reductions in viability were observed in some of the culture systems tested. Various combinations of media, sera, buffers and organ explant cultures were tested. All cultures were incubated at 37 C in an atmosphere of 95% air and 5% CO2. Larvae underwent growth and differentiation to the L4 in all medium-serum combinations with and without organ explant cultures. Development and growth did occur but viability was reduced to insignificant levels in media without serum or cells. Optimal growth, differentiation, and longevity were observed in bicarbonate buffered RPMI-1640 containing 10% fetal calf serum and gerbil (Meriones unguiculatus) cecum explant cultures. Observations indicated that Strongylus vulgaris and Strongylus equinus also developed to the L4 stage using similar techniques. However, viability of S. vulgaris L4 was markedly limited. Specific morphological changes marked phases of development of S. edentatus, categorized as early, middle and late third stage, third molt and early fourth stage. Strongylus equinus appeared to follow the same developmental pattern in vitro as S. edentatus. Distinct differences in morphological features during differentiation were observed between S. edentatus and S. vulgaris.

Growth and Survival of Larval Alewife (Alosa pseudoharengus) in Southern New England Lakes

NASA Astrophysics Data System (ADS)

Suca, J.; Jones, A.; Llopiz, J.

2016-02-01

Alewives (Alosa pseudoharengus) are ecologically and commercially important anadromous fish in eastern North America, and populations have declined to close to 1% of their historic levels. Despite moratoriums in recent years in most US states, there has been little recovery of alewives. In light of this poor recovery, we examined the factors that influence the survival of alewife larvae that were spawned in multiple freshwater systems in Massachusetts. Four lakes were sampled each week throughout the spring and summer for fish larvae, zooplankton and physicochemical parameters. Abundances of larvae from the lakes were analyzed, along with environmental factors. In the lab, otoliths of larvae from two different lakes were used for age and growth rate determination, as well as examining selective mortality during the larval period. Additionally, differences in growth and selective mortality of early and late spawned larvae were analyzed to investigate the tradeoffs between spawning early versus late in the spawning season. Abundances varied greatly between lakes and sampling times. Through otolith analysis, differences in growth rates between lakes were observed. This is likely due to differences in either temperature or food availability, and ongoing work quantifying zooplankton abundances will address these potential factors. Interestingly, there was no evidence for selective mortality in the two lakes examined, a result that is consistent with the hypothesis that anadromy in this species evolved as a strategy to minimize predation during the vulnerable larval period.

Offshore-onshore linkages in the larval life history of sole in the Gulf of Lions (NW-Mediterranean)

NASA Astrophysics Data System (ADS)

Morat, Fabien; Letourneur, Yves; Blamart, Dominique; Pécheyran, Christophe; Darnaude, Audrey M.; Harmelin-Vivien, Mireille

2014-08-01

Understanding individual dispersion from offshore natal areas to coastal nurseries during pelagic larval life is especially important for the sustainable management of exploited marine fish species. For several years, the hatching period, the larval life duration, the average growth rate and the otolith chemical composition (δ13C, δ18O, Sr:Ca and Ba:Ca) during the larval life were studied for young of the year (YOY) of sole collected in three main nurseries of the Gulf of Lions (GoL) (Thau, Mauguio and Berre). We investigated the spatial variation in the origin of the sole larvae which colonised the nurseries around the GoL, and whether temporal differences in environmental conditions during this life stage affected growth and larval life duration. The hatching period ranges from October to March, depending on year and site. Average ages at metamorphosis varied between 43 and 50 days, with the lowest and highest values consistently found for Mauguio and Berre, respectively. Otolith growth rates ranged between 2.7 and 3.2 μm d-1, with the lowest values in Thau and Mauguio and the highest in Berre. Otolith chemical composition during the larval life also varied, suggesting contrasted larval environmental histories in YOY among nurseries. In fishes from Berre and Mauguio, larval life was more influenced by the Rhône River, showing consistently higher larval Ba:Ca ratios (10/23 μmol mol-1) and lower δ13C (-6.5/-6.1‰) and δ18O values (-1.6/0.1‰) than for Thau (with Ba:Ca ratios < 8 μmol mol-1, δ13C ˜-2.3‰ and δ18O ˜1.5‰). Differences in larval otolith composition were observed for 2004, with higher Ba:Ca and lower δ13C and δ18O values than in the two other years. These differences were explained by changes in composition and chemical signatures of water masses after an exceptional flooding event of the Rhône River in late 2003.

CLOCK expression identifies developing circadian oscillator neurons in the brains of Drosophila embryos.

PubMed

Houl, Jerry H; Ng, Fanny; Taylor, Pete; Hardin, Paul E

2008-12-18

The Drosophila circadian oscillator is composed of transcriptional feedback loops in which CLOCK-CYCLE (CLK-CYC) heterodimers activate their feedback regulators period (per) and timeless (tim) via E-box mediated transcription. These feedback loop oscillators are present in distinct clusters of dorsal and lateral neurons in the adult brain, but how this pattern of expression is established during development is not known. Since CLK is required to initiate feedback loop function, defining the pattern of CLK expression in embryos and larvae will shed light on oscillator neuron development. A novel CLK antiserum is used to show that CLK expression in the larval CNS and adult brain is limited to circadian oscillator cells. CLK is initially expressed in presumptive small ventral lateral neurons (s-LNvs), dorsal neurons 2 s (DN2s), and dorsal neuron 1 s (DN1s) at embryonic stage (ES) 16, and this CLK expression pattern persists through larval development. PER then accumulates in all CLK-expressing cells except presumptive DN2s during late ES 16 and ES 17, consistent with the delayed accumulation of PER in adult oscillator neurons and antiphase cycling of PER in larval DN2s. PER is also expressed in non-CLK-expressing cells in the embryonic CNS starting at ES 12. Although PER expression in CLK-negative cells continues in ClkJrk embryos, PER expression in cells that co-express PER and CLK is eliminated. These data demonstrate that brain oscillator neurons begin development during embryogenesis, that PER expression in non-oscillator cells is CLK-independent, and that oscillator phase is an intrinsic characteristic of brain oscillator neurons. These results define the temporal and spatial coordinates of factors that initiate Clk expression, imply that circadian photoreceptors are not activated until the end of embryogenesis, and suggest that PER functions in a different capacity before oscillator cell development is initiated.

Interannual variations in the hatching pattern, larval growth and otolith size of a sand-dwelling fish from central Chile

NASA Astrophysics Data System (ADS)

Rodríguez-Valentino, Camilo; Landaeta, Mauricio F.; Castillo-Hidalgo, Gissella; Bustos, Claudia A.; Plaza, Guido; Ojeda, F. Patricio

2015-09-01

The interannual variation (2010-2013) of larval abundance, growth and hatching patterns of the Chilean sand stargazer Sindoscopus australis (Pisces: Dactyloscopidae) was investigated through otolith microstructure analysis from samples collected nearshore (<500 m from shore) during austral late winter-early spring off El Quisco bay, central Chile. In the studied period, the abundance of larval stages in the plankton samples varied from 2.2 to 259.3 ind. 1000 m-3; larval abundance was similar between 2010 and 2011, and between 2012 and 2013, but increased significantly from 2011 to 2012. The estimated growth rates increased twice, from 0.09 to 0.21 mm day-1, between 2011 and 2013. Additionally, otolith size (radius, perimeter and area), related to body length of larvae, significantly decreased from 2010 to 2012, but increases significantly in 2013. Although the mean values of microincrement widths of sagitta otoliths were similar between 2010 and 2011 (around 0.6-0.7 μm), the interindividual variability increases in 2011 and 2013, suggesting large environmental variability experienced by larvae during these years. Finally, the hatching pattern of S. australis changed significantly from semi-lunar to lunar cycle after 2012.

Anopheles larval abundance and diversity in three rice agro-village complexes Mwea irrigation scheme, central Kenya.

PubMed

Mwangangi, Joseph M; Shililu, Josephat; Muturi, Ephantus J; Muriu, Simon; Jacob, Benjamin; Kabiru, Ephantus W; Mbogo, Charles M; Githure, John; Novak, Robert J

2010-08-09

The diversity and abundance of Anopheles larvae has significant influence on the resulting adult mosquito population and hence the dynamics of malaria transmission. Studies were conducted to examine larval habitat dynamics and ecological factors affecting survivorship of aquatic stages of malaria vectors in three agro-ecological settings in Mwea, Kenya. Three villages were selected based on rice husbandry and water management practices. Aquatic habitats in the 3 villages representing planned rice cultivation (Mbui Njeru), unplanned rice cultivation (Kiamachiri) and non-irrigated (Murinduko) agro-ecosystems were sampled every 2 weeks to generate stage-specific estimates of mosquito larval densities, relative abundance and diversity. Records of distance to the nearest homestead, vegetation coverage, surface debris, turbidity, habitat stability, habitat type, rice growth stage, number of rice tillers and percent Azolla cover were taken for each habitat. Captures of early, late instars and pupae accounted for 78.2%, 10.9% and 10.8% of the total Anopheles immatures sampled (n = 29,252), respectively. There were significant differences in larval abundance between 3 agro-ecosystems. The village with 'planned' rice cultivation had relatively lower Anopheles larval densities compared to the villages where 'unplanned' or non-irrigated. Similarly, species composition and richness was higher in the two villages with either 'unplanned' or limited rice cultivation, an indication of the importance of land use patterns on diversity of larval habitat types. Rice fields and associated canals were the most productive habitat types while water pools and puddles were important for short periods during the rainy season. Multiple logistic regression analysis showed that presence of other invertebrates, percentage Azolla cover, distance to nearest homestead, depth and water turbidity were the best predictors for Anopheles mosquito larval abundance. These results suggest that agricultural practices have significant influence on mosquito species diversity and abundance and that certain habitat characteristics favor production of malaria vectors. These factors should be considered when implementing larval control strategies which should be targeted based on habitat productivity and water management.

Lecithotrophic behaviour in zoea and megalopa larvae of the ghost shrimp Lepidophthalmus siriboia Felder and Rodrigues, 1993 (Decapoda: Callianassidae).

PubMed

Abrunhosa, Fernando A; Simith, Darlan J B; Palmeira, Carlos A M; Arruda, Danielle C B

2008-12-01

Food supply is considered critical for a successful culturing of decapod larvae. However, some species may present yolk reserve sufficient to complete their larval development without external food supply (known as lecithotrophic larval development). In the present study, two experiments were carried out in order to verify whether the callianassid Lepidophthalmus siriboia have lecithotrophic behaviour or, if they need external food for their larval development: Experiment 1, larvae submitted to an initial feeding period and Experiment 2, larvae submitted to an initial starvation period. High survival rate was observed in both experiments, in which only 2 megalopae and 1 zoea III died. These results strongly suggest that larvae of L. siriboia are lecithotrophic as they have sufficiently large yolk reserve to complete their larval development, while the megalopa stage shows facultative lecithotrophy. The larval periods of each stage of the treatments were quite similar and, despite some significant differences in some larval periods, these can be related probably to larval rearing conditions, abiotic factors or, individual variability of larval health, as well as stress caused to the ovigerous females during embryogenesis.

Effectiveness of artificial bark flaps in mediating migration of late-instar gypsy moth larvae

Treesearch

Michael L. McManus; Harvey R. Smith

1984-01-01

Field studies demonstrated that migrating larval instars of the gypsy moth, Lymantria dispar (L.), preferred resting locations placed on tree boles at 4.6 m over those placed at 1.5 and 3 m. More larvae were found beneath bark flaps than beneath flaps of hard black plastic.

Relationships between maternal engorgement weight and the number, size, and fat content of larval Ixodes scapularis (Acari: Ixodidae)

USGS Publications Warehouse

Ginsberg, Howard; Lee, Chong; Volson, Barry; Dyer, Megan C.; LeBrun, Roger A.

2017-01-01

The relationship between engorgement weight of female Ixodes scapularis Say and characteristics of offspring was studied using field-collected females fed on rabbits in the laboratory. The number of eggs laid was positively related to maternal engorgement weight in one trial, and larval size (estimated by scutal area) was positively related to maternal engorgement weight in the other. These results suggest a trade-off in number of eggs produced versus average size of offspring, possibly determined during late engorgement. The adults for the two trials were collected from different sites in southern Rhode Island and in different seasons (the fall adults were newly emerged, while the spring adults had presumably lived through the winter), so it is not clear whether these results reflect genetic differences or subtle environmental differences between trials. Percent egg hatch and average fat content of larvae were not related to female engorgement weight. We present a modified method to measure lipid content of pooled larval ticks.

Evolutionary modification of mesenchyme cells in sand dollars in the transition from indirect to direct development.

PubMed

Yajima, Mamiko

2007-01-01

Peronella japonica, an intermediate type of direct-developing sand dollar, forms an abbreviated pluteus, followed by metamorphosis within 3 days without feeding. In this species, ingression of mesenchyme cells starts before hatching and continues until gastrulation, but no typical secondary mesenchyme cells (SMCs) migrate from the tip of the archenteron. Here, I investigated the cell lineage of mesenchyme cells through metamorphosis in P. japonica and found that mesenchyme cells migrating before hatching (early mesenchyme cells [EMCs]) were exclusively derived from micromeres and became larval skeletogenic cells, whereas cells migrating after hatching (late mesenchyme cells [LMCs]) appeared to contain several nonskeletogenic cells. Thus, it is likely that EMCs are homologous to primary mesenchyme cells (PMCs) and LMCs are similar to the SMCs of typical indirect developers, suggesting that heterochrony in the timing of mesenchyme cell ingression may have occurred in this species. EMCs disappeared after metamorphosis and LMCs were involved in adult skeletogenesis. Embryos from which micromeres were removed at the 16-cell stage formed armless plutei that went on to form adult skeletons and resulted in juveniles with normal morphology. These results suggest that in P. japonica, LMCs form adult skeletal elements, whereas EMCs are specialized for larval spicule formation. The occurrence of evolutionary modifications in mesenchyme cells in the transition from indirect to direct development of sand dollars is discussed.

Crowding of Drosophila larvae affects lifespan and other life-history traits via reduced availability of dietary yeast.

PubMed

Klepsatel, Peter; Procházka, Emanuel; Gáliková, Martina

2018-06-19

Conditions experienced during development have often long-lasting effects persisting into adulthood. In Drosophila, it is well-documented that larval crowding influences fitness-related traits such as body size, starvation resistance and lifespan. However, the underlying mechanism of this phenomenon is not well understood. Here, we show that the effects of increased larval density on life-history traits can be explained by decreased yeast availability in the diet during development. Yeast-poor larval diet alters various life-history traits and mimics the effects of larval crowding. In particular, reduced amount of yeast in larval diet prolongs developmental time, reduces body size, increases body fat content and starvation resistance, and prolongs Drosophila lifespan. Conversely, the effects of larval crowding can be rescued by increasing the concentration of the dietary yeast in the diet during development. Altogether, our results show that the well-known effects of larval crowding on life-history traits are mainly caused by the reduced availability of dietary yeasts due to increased larval competition. Copyright © 2018. Published by Elsevier Inc.

Larval development of the subantarctic king crabs Lithodes santolla and Paralomis granulosa reared in the laboratory

NASA Astrophysics Data System (ADS)

Calcagno, J. A.; Anger, K.; Lovrich, G. A.; Thatje, S.; Kaffenberger, A.

2004-02-01

The larval development and survival in the two subantarctic lithodid crabs Lithodes santolla (Jaquinot) and Paralomis granulosa (Molina) from the Argentine Beagle Channel were studied in laboratory cultures. In L. santolla, larval development lasted about 70 days, passing through three zoeal stages and the megalopa stage, with a duration of approximately 4, 7, 11 and 48 days, respectively. The larval development in P. granulosa is more abbreviated, comprising only two zoeal stages and the megalopa stage, with 6, 11 and 43 days' duration, respectively. In both species, we tested for effects of presence versus absence of food (Artemia nauplii) on larval development duration and survival rate. In P. granulosa, we also studied effects of different rearing conditions, such as individual versus mass cultures, as well as aerated versus unaerated cultures. No differences in larval development duration and survival were observed between animals subjected to those different rearing conditions. The lack of response to the presence or absence of potential food confirms, in both species, a complete lecithotrophic mode of larval development. Since lithodid crabs are of high economic importance in the artisanal fishery in the southernmost parts of South America, the knowledge of optimal rearing conditions for lithodid larvae is essential for future attempts at repopulating the collapsing natural stocks off Tierra del Fuego.

The Implications of Temperature-Mediated Plasticity in Larval Instar Number for Development within a Marine Invertebrate, the Shrimp Palaemonetes varians

PubMed Central

Oliphant, Andrew; Hauton, Chris; Thatje, Sven

2013-01-01

Variations in larval instar number are common among arthropods. Here, we assess the implications of temperature-mediated variations in larval instar number for larval development time, larval growth rates, and juvenile dry weight within the palaemonid shrimp, Palaemonetes varians. In contrast with previous literature, which focuses on terrestrial arthropods, particularly model and pest species often of laboratory lines, we use wild shrimp, which differ in their life history from previous models. Newly-hatched P. varians larvae were first reared at 5, 10, 17, 25, and 30°C to assess their thermal scope for development. Larvae developed at 17, 25, and 30°C. At higher temperatures, larvae developed through fewer larval instars. Two dominant developmental pathways were observed; a short pathway of four instars and a long pathway of five instars. Longer developmental pathways of six to seven instars were rarely observed (mostly at lower temperatures) and consisted of additional instars as ‘repeat’ instars; i.e. little developmental advance over the preceding instar. To assess the implications of temperature-mediated variation in larval instar number, newly-hatched larvae were then reared at 15, 20, and 25°C. Again, the proportion of larvae developing through four instars increased with temperature. At all temperatures, larval development time and juvenile dry weight were greater for larvae developing through five instars. Importantly, because of the increasing proportion of larvae developing through four instars with increasing temperature, larval traits associated with this pathway (reduced development time and juvenile dry weight) became more dominant. As a consequence of increasing growth rate with temperature, and the shift in the proportion of larvae developing through four instars, juvenile dry weight was greatest at intermediate temperatures (20°C). We conclude that at settlement P. varians juveniles do not follow the temperature-size rule; this is of importance for life-history ecology in response to environmental change, as well as for aquaculture applications. PMID:24069450

The implications of temperature-mediated plasticity in larval instar number for development within a marine invertebrate, the shrimp Palaemonetes varians.

PubMed

Oliphant, Andrew; Hauton, Chris; Thatje, Sven

2013-01-01

Variations in larval instar number are common among arthropods. Here, we assess the implications of temperature-mediated variations in larval instar number for larval development time, larval growth rates, and juvenile dry weight within the palaemonid shrimp, Palaemonetes varians. In contrast with previous literature, which focuses on terrestrial arthropods, particularly model and pest species often of laboratory lines, we use wild shrimp, which differ in their life history from previous models. Newly-hatched P. varians larvae were first reared at 5, 10, 17, 25, and 30 °C to assess their thermal scope for development. Larvae developed at 17, 25, and 30 °C. At higher temperatures, larvae developed through fewer larval instars. Two dominant developmental pathways were observed; a short pathway of four instars and a long pathway of five instars. Longer developmental pathways of six to seven instars were rarely observed (mostly at lower temperatures) and consisted of additional instars as 'repeat' instars; i.e. little developmental advance over the preceding instar. To assess the implications of temperature-mediated variation in larval instar number, newly-hatched larvae were then reared at 15, 20, and 25 °C. Again, the proportion of larvae developing through four instars increased with temperature. At all temperatures, larval development time and juvenile dry weight were greater for larvae developing through five instars. Importantly, because of the increasing proportion of larvae developing through four instars with increasing temperature, larval traits associated with this pathway (reduced development time and juvenile dry weight) became more dominant. As a consequence of increasing growth rate with temperature, and the shift in the proportion of larvae developing through four instars, juvenile dry weight was greatest at intermediate temperatures (20 °C). We conclude that at settlement P. varians juveniles do not follow the temperature-size rule; this is of importance for life-history ecology in response to environmental change, as well as for aquaculture applications.

Novel Metrics to Characterize Embryonic Elongation of the Nematode Caenorhabditis elegans.

PubMed

Martin, Emmanuel; Rocheleau-Leclair, Olivier; Jenna, Sarah

2016-03-28

Dissecting the signaling pathways that control the alteration of morphogenic processes during embryonic development requires robust and sensitive metrics. Embryonic elongation of the nematode Caenorhabditis elegans is a late developmental stage consisting of the elongation of the embryo along its longitudinal axis. This developmental stage is controlled by intercellular communication between hypodermal cells and underlying body-wall muscles. These signaling mechanisms control the morphology of hypodermal cells by remodeling the cytoskeleton and the cell-cell junctions. Measurement of embryonic lethality and developmental arrest at larval stages as well as alteration of cytoskeleton and cell-cell adhesion structures in hypodermal and muscle cells are classical phenotypes that have been used for more than 25 years to dissect these signaling pathways. Recent studies required the development of novel metrics specifically targeting either early or late elongation and characterizing morphogenic defects along the antero-posterior axis of the embryo. Here, we provide detailed protocols enabling the accurate measurement of the length and the width of the elongating embryos as well as the length of synchronized larvae. These methods constitute useful tools to identify genes controlling elongation, to assess whether these genes control both early and late phases of this stage and are required evenly along the antero-posterior axis of the embryo.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, L.; Miller, S.N.; Schmidtmann, E.T.

Potential larval habitats of the mosquito Culex tarsalis (Coquillett), implicated as a primary vector of West Nile virus in Wyoming, were identified using integrated remote sensing and geographic information system (GIS) analyses. The study area is in the Powder River Basin of north central Wyoming, an area that has been undergoing a significant increase in coalbed methane gas extractions since the late 1990s. Large volumes of water are discharged, impounded, and released during the extraction of methane gas, creating aquatic habitats that have the potential to support immature mosquito development. Landsat TM and ETM + data were initially classified intomore » spectrally distinct water and vegetation classes, which were in turn used to identify suitable larval habitat sites. This initial habitat classification was refined using knowledge-based GIS techniques requiring spatial data layers for topography, streams, and soils to reduce the potential for overestimation of habitat. Accuracy assessment was carried out using field data and high-resolution aerial photography commensurate with one of the Landsat images. The classifier can identify likely habitat for ponds larger than 0.8 ha (2 acres) with generally satisfactory results (72.1%) with a lower detection limit of approximate to 0.4 ha (1 acre). Results show a 75% increase in potential larval habitats from 1999 to 2004 in the study area, primarily because of the large increase in small coalbed methane water discharge ponds. These results may facilitate mosquito abatement programs in the Powder River Basin with the potential for application throughout the state and region.« less

A role for Lin-28 in growth and metamorphosis in Drosophila melanogaster.

PubMed

González-Itier, Sergio; Contreras, Esteban G; Larraín, Juan; Glavic, Álvaro; Faunes, Fernando

2018-06-13

Insect metamorphosis has been a classic model to understand the role of hormones in growth and timing of developmental transitions. In addition to hormones, transitions in some species are regulated by genetic programs, such as the heterochronic gene network discovered in C. elegans. However, the functional link between hormones and heterochronic genes is not clear. The heterochronic gene lin-28 is involved in the maintenance of stem cells, growth and developmental timing in vertebrates. In this work, we used gain-of-function and loss-of-function experiments to study the role of Lin-28 in larval growth and the timing of metamorphosis of Drosophila melanogaster. During the late third instar stage, Lin-28 is mainly expressed in neurons of the central nervous system and in the intestine. Loss-of-function lin-28 mutant larvae are smaller and the larval-to-pupal transition is accelerated. This faster transition correlates with increased levels of ecdysone direct target genes such as Broad-Complex (BR-C) and Ecdysone Receptor (EcR). Overexpression of Lin-28 does not affect the timing of pupariation but most animals are not able to eclose, suggesting defects in metamorphosis. Overexpression of human Lin-28 results in delayed pupariation and the death of animals during metamorphosis. Altogether, these results suggest that Lin-28 is involved in the control of growth during larval development and in the timing and progression of metamorphosis. Copyright © 2017. Published by Elsevier B.V.

Population and life-stage-specific effects of two herbicide formulations on the aquatic development of European common frogs (Rana temporaria).

PubMed

Wagner, Norman; Veith, Michael; Lötters, Stefan; Viertel, Bruno

2017-01-01

Environmental contamination is suggested to contribute to amphibian population declines. However, the effects of a contaminant on a particular amphibian species can differ among populations. The authors investigated the toxic effects of 2 herbicide formulations on different populations and on representative developmental stages of the European common frog (Rana temporaria). Larvae from forest populations were more sensitive to a commonly used glyphosate-based herbicide compared with individuals from agrarian land. Median lethal concentrations correlated with measured glyphosate levels in the breeding ponds, which may be a sign of evolved tolerances. The reverse result was observed for a less commonly used cycloxydim-based herbicide. Effects of the glyphosate-based herbicide were stronger for earlier larval stages compared with later larval stages. Hence, applications in early spring (when early larvae are present in breeding ponds) pose greater risk concerning acute toxic effects on R. temporaria. With regard to late larval stages, short exposure (96 h) of prometamorphic larvae prolonged time to metamorphosis, but only at the highest test concentration that did not significantly induce mortality. This could be due to impairment of the thyroid axis. Notably, nearly all test concentrations of the 2 herbicides provoked growth retardation. Further research on how evolved or induced tolerances are acquired, actual contamination levels of amphibian habitats, and potential endocrine effects of glyphosate-based herbicides is necessary. Environ Toxicol Chem 2017;36:190-200. © 2016 SETAC. © 2016 SETAC.

Corn rootworms (Coleoptera: Chrysomelidae) in space and time

NASA Astrophysics Data System (ADS)

Park, Yong-Lak

Spatial dispersion is a main characteristic of insect populations. Dispersion pattern provides useful information for developing effective sampling and scouting programs because it affects sampling accuracy, efficiency, and precision. Insect dispersion, however, is dynamic in space and time and largely dependent upon interactions among insect, plant and environmental factors. This study investigated the spatial and temporal dynamics of corn rootworm dispersion at different spatial scales by using the global positioning system, the geographic information system, and geostatistics. Egg dispersion pattern was random or uniform in 8-ha cornfields, but could be aggregated at a smaller scale. Larval dispersion pattern was aggregated regardless of spatial scales used in this study. Soil moisture positively affected corn rootworm egg and larval dispersions. Adult dispersion tended to be aggregated during peak population period and random or uniform early and late in the season and corn plant phenology was a major factor to determine dispersion patterns. The dispersion pattern of root injury by corn rootworm larval feeding was aggregated and the degree of aggregation increased as the root injury increased within the range of root injury observed in microscale study. Between-year relationships in dispersion among eggs, larvae, adult, and environment provided a strategy that could predict potential root damage the subsequent year. The best prediction map for the subsequent year's potential root damage was the dispersion maps of adults during population peaked in the cornfield. The prediction map was used to develop site-specific pest management that can reduce chemical input and increase control efficiency by controlling pests only where management is needed. This study demonstrated the spatio-temporal dynamics of insect population and spatial interactions among insects, plants, and environment.

Fatty acid profiles of phyllosoma larvae of western rock lobster (Panulirus cygnus) in cyclonic and anticyclonic eddies of the Leeuwin Current off Western Australia

NASA Astrophysics Data System (ADS)

Wang, M.; O'Rorke, R.; Waite, A. M.; Beckley, L. E.; Thompson, P.; Jeffs, A. G.

2014-03-01

The recent dramatic decline in settlement in the population of the spiny lobster, Panulirus cygnus, may be due to changes in the oceanographic processes that operate offshore of Western Australia. It has been suggested that this decline could be related to poor nutritional condition of the post-larvae, especially lipid which is accumulated in large quantities during the preceding extensive pelagic larval stage. The current study focused on investigations into the lipid content and fatty acid (FA) profiles of lobster phyllosoma larvae from three mid to late stages of larval development (stages VI, VII, VIII) sampled from two cyclonic and two anticyclonic eddies of the Leeuwin Current off Western Australia. The results showed significant accumulation of lipid and energy storage FAs with larval development regardless of location of capture, however, larvae from cyclonic eddies had more lipid and FAs associated with energy storage than larvae from anticyclonic eddies. FA food chain markers from the larvae indicated significant differences in the food webs operating in the two types of eddy, with a higher level of FA markers for production from flagellates and a lower level from copepod grazing in cyclonic versus anticyclonic eddies. The results indicate that the microbial food web operating in cyclonic eddies provides better feeding conditions for lobster larvae despite anticyclonic eddies being generally more productive and containing greater abundances of zooplankton as potential prey for lobster larvae. Gelatinous zooplankton, such as siphonophores, may play an important role in cyclonic eddies by accumulating dispersed microbial nutrients and making them available as larger prey for phyllosoma. The markedly superior nutritional condition of lobster larvae feeding in the microbial food web found in cyclonic eddies, could greatly influence their subsequent settlement and recruitment to the coastal fishery.

Patterns in connectivity and retention of simulated Tanner crab (Chionoecetes bairdi) larvae in the eastern Bering Sea

NASA Astrophysics Data System (ADS)

Richar, Jonathan I.; Kruse, Gordon H.; Curchitser, Enrique; Hermann, Albert J.

2015-11-01

The eastern Bering Sea (EBS) population of Tanner crab (Chionoecetes bairdi) has exhibited high variability in recruitment to the commercially exploited stock since the late 1970s. Concurrently, apparent shifts in crab distribution have also been observed. Larval advection patterns and associated local retention offer a potential mechanism for these observations. The Regional Ocean Modeling System (ROMS) was used to simulate larval Tanner crab advection patterns over 1978-2004 based on larval hatching sites inferred from the distributions of reproductive females sampled during annual National Marine Fisheries Service trawl surveys. Connectivity among EBS subregions was examined by comparing start and end float locations after 60 days of simulated drift. High levels of retention (>50% of floats) were observed in the majority of source subregions, and contributed significantly to the total number of endpoints in each region. Patterns in advection and resultant interregional connectivity were variable, with strongest sustained connectivity occurring along shelf, within individual domains. Increased settlement potential in the outer domain and southern middle domain after 1990 is consistent with an observed geographic shift in fishery productivity. Apparent reliance of Bristol Bay on local larval retention validates recent spatial fishery management to conserve this area as a subpopulation.

Prevalence of Helicoverpa zea (Lepidoptera: Noctuidae) on late season volunteer corn in Mississippi: implications on Bt resistance management

USDA-ARS?s Scientific Manuscript database

The southern United States has a long growing period between corn harvest and first winter frost, so volunteer corn which germinates after corn harvest has a growing period sufficient for corn earworm, Helicoverpa zea (Boddie) to feed on these plants. However, lower air temperatures can limit larval...

Characterization of glycosaminoglycans during tooth development and mineralization in the axolotl, Ambystoma mexicanum.

PubMed

Wistuba, J; Völker, W; Ehmcke, J; Clemen, G

2003-10-01

Glycosaminoglycans (GAGs) involved in the formation of the teeth of Ambystoma mexicanum were located and characterized with the cuprolinic blue (CB) staining method and transmission electron microscopy (TEM). Glycosaminoglycan-cuprolinic blue precipitates (GAGCB) were found in different compartments of the mineralizing tissue. Various populations of elongated GAGCB could be discriminated both according to their size and their preferential distribution in the extracellular matrix (ECM). GAGCB populations that differ in their composition could be attributed not only to the compartments of the ECM but also to different zones and to different tooth types (early-larval and transformed). Larger precipitates were only observed within the dentine matrix of the shaft of the early-larval tooth. The composition of the populations differed significantly between the regions of the transformed tooth: pedicel, shaft and dividing zone. In later stages of tooth formation, small-sized GAGCBs were seen as intracellular deposits in the ameloblasts. It is concluded that the composition of GAGCB populations seems to play a role in the mineralization processes during tooth development in A. mexicanum and influence qualitative characteristics of the mineral in different tooth types and zones, and it is suggested that GAGs might be resorbed by the enamel epithelium during the late phase of enamel formation.

Temporal and spatial variations in microclimate influence the larval foraging behaviors and performance of a conifer-feeding sawfly.

PubMed

Johns, R C; Boone, J; Leggo, J J; Smith, S; Carleton, D; Quiring, D T

2012-06-01

Herbivorous insects are often exposed to broad temporal and spatial variations in microclimate conditions within their host plants and have adapted a variety of behaviors, such as avoidance or basking, to either offset or benefit from such variation. Field experiments were carried out to investigate the influence of daily and intratree variations in microclimate on the behaviors (feeding, resting, dispersal, and hiding) and associated performance of late-instar larvae of the yellowheaded spruce sawfly, Pikonema alaskensis (Rohwer) (Hymenoptera: Tenthredinidae) within crowns of 1.25-1.5 m tall black spruce (Picea mariana [Miller] Britton Sterns Poggenburg); late instars feed on developing shoots of young spruce and are often exposed to microclimatic extremes with unknown effects on performance. Larvae fed diurnally from just after dawn (0800 h) until dusk (2000 h) and rested throughout the night, with brief periods of dispersal occurring in the morning and evening. Neither larval behavior nor abiotic conditions differed significantly between the upper and lower crowns of trees. Temperature, humidity, and solar insolation all explained >90% of variation in feeding; however, sunrise and sunset were the most likely cues influencing diurnal behavior. Most larvae (94%) fed on the bottom, shaded side of shoots, and field experiments indicated that this behavior is adaptive with respect to microclimate, probably reducing hygrothermal stress. Thus, behavioral adaptations by P. alaskensis to daily and within-shoot microclimatic variation may reduce the risk of hygrothermal stress during dispersal or feeding, while still allowing larvae to feed on the preferred and highly nutritious upper crown foliage of young spruce.

Carryover effects of larval exposure to different environmental bacteria drive adult trait variation in a mosquito vector

PubMed Central

Dickson, Laura B.; Jiolle, Davy; Minard, Guillaume; Moltini-Conclois, Isabelle; Volant, Stevenn; Ghozlane, Amine; Bouchier, Christiane; Ayala, Diego; Paupy, Christophe; Moro, Claire Valiente; Lambrechts, Louis

2017-01-01

Conditions experienced during larval development of holometabolous insects can affect adult traits, but whether differences in the bacterial communities of larval development sites contribute to variation in the ability of insect vectors to transmit human pathogens is unknown. We addressed this question in the mosquito Aedes aegypti, a major arbovirus vector breeding in both sylvatic and domestic habitats in Sub-Saharan Africa. Targeted metagenomics revealed differing bacterial communities in the water of natural breeding sites in Gabon. Experimental exposure to different native bacterial isolates during larval development resulted in significant differences in pupation rate and adult body size but not life span. Larval exposure to an Enterobacteriaceae isolate resulted in decreased antibacterial activity in adult hemolymph and reduced dengue virus dissemination titer. Together, these data provide the proof of concept that larval exposure to different bacteria can drive variation in adult traits underlying vectorial capacity. Our study establishes a functional link between larval ecology, environmental microbes, and adult phenotypic variation in a holometabolous insect vector. PMID:28835919

Muscle organizers in Drosophila: the role of persistent larval fibers in adult flight muscle development

NASA Technical Reports Server (NTRS)

Farrell, E. R.; Fernandes, J.; Keshishian, H.

1996-01-01

In many organisms muscle formation depends on specialized cells that prefigure the pattern of the musculature and serve as templates for myoblast organization and fusion. These include muscle pioneers in insects and muscle organizing cells in leech. In Drosophila, muscle founder cells have been proposed to play a similar role in organizing larval muscle development during embryogenesis. During metamorphosis in Drosophila, following histolysis of most of the larval musculature, there is a second round of myogenesis that gives rise to the adult muscles. It is not known whether muscle founder cells organize the development of these muscles. However, in the thorax specific larval muscle fibers do not histolyze at the onset of metamorphosis, but instead serve as templates for the formation of a subset of adult muscles, the dorsal longitudinal flight muscles (DLMs). Because these persistent larval muscle fibers appear to be functioning in many respects like muscle founder cells, we investigated whether they were necessary for DLM development by using a microbeam laser to ablate them singly and in combination. We found that, in the absence of the larval muscle fibers, DLMs nonetheless develop. Our results show that the persistent larval muscle fibers are not required to initiate myoblast fusion, to determine DLM identity, to locate the DLMs in the thorax, or to specify the total DLM fiber volume. However, they are required to regulate the number of DLM fibers generated. Thus, while the persistent larval muscle fibers are not obligatory for DLM fiber formation and differentiation, they are necessary to ensure the development of the correct number of fibers.

Efficacy of Four Nematicides Against the Reproduction and Development of Pinewood Nematode, Bursaphelenchus xylophilus

PubMed Central

Bi, Zhenzhen; Gong, Yanting; Huang, Xiaojuan; Yu, Hongshi; Bai, Liqun; Hu, Jiafu

2015-01-01

To understand the efficacy of emamectin benzoate, avermectin, milbemectin, and thiacloprid on the reproduction and development of Bursaphelenchus xylophilus, seven parameters, namely population growth, fecundity, egg hatchability, larval lethality, percent larval development, body size, and sexual ratio, were investigated using sublethal (LC20) doses of these compounds in the laboratory. Emamectin benzoate treatment led to a significant suppression in population size, brood size, and percent larval development with 411, 3.50, and 49.63%, respectively, compared to 20850, 24.33, and 61.43% for the negative control. The embryonic and larval lethality increased obviously from 12.47% and 13.70% to 51.37% and 75.30%, respectively. In addition, the body length was also significantly reduced for both males and females in the emamectin benzoate treatment. Avermectin and milbemectin were also effective in suppressing population growth by increasing larval lethality and reducing larval development, although they did not affect either brood size or embryonic lethality. Body length for both male and female worms was increased by avermectin. Thiacloprid caused no adverse reproductive effects, although it suppressed larval development. Sexual ratio was not affected by any of these four nematicides. Our results indicate that emamectin benzoate, milbemectin, and avermectin are effective against the reproduction of B. xylophilus. We think these three nematicides can be useful for the control of pine wilt disease. PMID:26170474

Efficacy of Four Nematicides Against the Reproduction and Development of Pinewood Nematode, Bursaphelenchus xylophilus.

PubMed

Bi, Zhenzhen; Gong, Yanting; Huang, Xiaojuan; Yu, Hongshi; Bai, Liqun; Hu, Jiafu

2015-06-01

To understand the efficacy of emamectin benzoate, avermectin, milbemectin, and thiacloprid on the reproduction and development of Bursaphelenchus xylophilus, seven parameters, namely population growth, fecundity, egg hatchability, larval lethality, percent larval development, body size, and sexual ratio, were investigated using sublethal (LC20) doses of these compounds in the laboratory. Emamectin benzoate treatment led to a significant suppression in population size, brood size, and percent larval development with 411, 3.50, and 49.63%, respectively, compared to 20850, 24.33, and 61.43% for the negative control. The embryonic and larval lethality increased obviously from 12.47% and 13.70% to 51.37% and 75.30%, respectively. In addition, the body length was also significantly reduced for both males and females in the emamectin benzoate treatment. Avermectin and milbemectin were also effective in suppressing population growth by increasing larval lethality and reducing larval development, although they did not affect either brood size or embryonic lethality. Body length for both male and female worms was increased by avermectin. Thiacloprid caused no adverse reproductive effects, although it suppressed larval development. Sexual ratio was not affected by any of these four nematicides. Our results indicate that emamectin benzoate, milbemectin, and avermectin are effective against the reproduction of B. xylophilus. We think these three nematicides can be useful for the control of pine wilt disease.

Cold hardiness of emerald ash borer, Agrilus planipennis: a new perspective

Treesearch

Robert C. Venette; Mark Abrahamson

2010-01-01

This study was designed to assess the cold hardiness of emerald ash borer larvae, the overwintering stage of the insect. We began by measuring larval supercooling points, the temperatures at which larvae freeze. We found that larvae collected from naturally infested trees in St. Paul, MN between late October and early December had an average supercooling point of -25...

North to Alaska: Evidence for conveyor belt transport of Dungeness crab larvae along the west coast of the United States and Canada

USGS Publications Warehouse

Park, W.; Douglas, David C.; Shirley, Thomas C.

2007-01-01

We propose and evaluate the hypothesis that Dungeness crab (Cancer magister) larvae from the northwestern coast of the United States and Canada can be transported northward to southeastern Alaska. Larvae collected in southeastern Alaska during May and June 1997–2004 had abundances and stages that varied seasonally, interannually, and spatially. An unexpected presence of late-stage larvae in spring raises a question regarding their origin, and the most plausible explanation is that they hatched off the northern Washington and British Columbia coasts and were transported to southeastern Alaska. Buoy drift tracks support the hypothesis that larvae released off the northern Washington and British Columbia coasts during the peak hatching season can be physically transported to southeastern Alaska, arriving as late-stage larvae in May and June, when local larvae are only beginning to hatch. A northward spring progression of monthly mean 7°C SST isotherms and phytoplankton blooms provide further evidence that environmental conditions are conducive for larval growth and metabolism during the transport period. The proposed larval transport suggests possible unidirectional gene flow between southern and northern populations of Dungeness crabs in southeastern Alaska.

Is mosquito larval source management appropriate for reducing malaria in areas of extensive flooding in The Gambia? A cross-over intervention trial.

PubMed

Majambere, Silas; Pinder, Margaret; Fillinger, Ulrike; Ameh, David; Conway, David J; Green, Clare; Jeffries, David; Jawara, Musa; Milligan, Paul J; Hutchinson, Robert; Lindsay, Steven W

2010-02-01

Larviciding to control malaria was assessed in rural areas with extensive seasonal flooding. Larval and adult mosquitoes and malaria incidence were surveyed routinely in four 100-km(2) areas either side of the Gambia River. Baseline data were collected in 2005. Microbial larvicide was applied to all water bodies by hand application with water-dispersible granular formulations and corn granules weekly from May to November in two areas in 2006 and in the other two areas in 2007 in a cross-over design. The intervention was associated with a reduction in habitats with late stage anopheline larvae and an 88% reduction in larval densities (P < 0.001). The effect of the intervention on mosquito densities was not pronounced and was confounded by the distance of villages to the major breeding sites and year (P = 0.002). There was no reduction in clinical malaria or anemia. Ground applications of non-residual larvicides with simple equipment are not effective in riverine areas with extensive flooding, where many habitats are poorly demarcated, highly mobile, and inaccessible on foot.

Zooplankton variability and larval striped bass foraging: Evaluating potential match/mismatch regulation

USGS Publications Warehouse

Chick, J.H.; Van Den Avyle, M.J.

1999-01-01

We quantified temporal and spatial variability of zooplankton in three potential nursery sites (river, transition zone, lake) for larval striped bass (Morone saxatilis) in Lake Marion, South Carolina, during April and May 1993-1995. In two of three years, microzooplankton (rotifers and copepod nauplii) density was significantly greater in the lake site than in the river or transition zone. Macrozooplankton (>200 ??m) composition varied among the three sites in all years with adult copepods and cladocerans dominant at the lake, and juvenile Corbicula fluminea dominant at the river and transition zone. Laboratory feeding experiments, simulating both among-site (site treatments) and within-site (density treatments) variability, were conducted in 1995 to quantify the effects of the observed zooplankton variability on foraging success of larval striped bass. A greater proportion of larvae fed in the lake than in the river or transition-zone treatments across all density treatments: mean (x), 10x and 100x. Larvae also ingested significantly more dry mass of prey in the lake treatment in both the mean and 10x density treatments. Field zooplankton and laboratory feeding data suggest that both spatial and temporal variability of zooplankton influence larval striped bass foraging. Prey density levels that supported successful foraging in our feeding experiments occurred in the lake during late April and May in 1994 and 1995 but were never observed in the river or transition zone. Because the rivers flowing into Lake Marion are regulated, it may be possible to devise flow management schemes that facilitate larval transport to the lake and thereby increase the proportion of larvae matched to suitable prey resources.

Experimental studies on the larval development of the shrimps Crangon crangon and C. allmanni

NASA Astrophysics Data System (ADS)

Criales, M. M.; Anger, K.

1986-09-01

Larvae of the shrimps Crangon crangon L. and C. allmanni Kinahan were reared in the laboratory from hatching through metamorphosis. Effects of rearing methods (larval density, application of streptomycin, food) and of salinity on larval development were tested only in C. crangon, influence of temperature was studied in both species. Best results were obtained when larvae were reared individually, with a mixture of Artemia sp. and the rotifer Brachionus plicatilis as food. Streptomycin had partly negative effects and was thus not adopted for standard rearing techniques. All factors tested in this study influenced not only the rates of larval survival and moulting, but also morphogenesis. In both species, in particular in C. crangon, a high degree of variability in larval morphology and in developmental pathways was observed. Unsuitable conditions, e.g. crowding in mass culture, application of antibiotics, unsuitable food (rotifers, phytoplankton), extreme temperatures and salinities, tend to increase the number of larval instars and of morphological forms. The frequency of moulting is controlled mainly by temperature. Regression equations describing the relations between the durations of larval instars and temperature are given for both Crangon species. The number of moults is a linear function of larval age and a power function of temperature. There is high variation in growth (measured as carapace length), moulting frequency, morphogenesis, and survival among hatches originating from different females. The interrelations between these different measures of larval development in shrimps and prawns are discussed.

Microarray analysis of a salamander hopeful monster reveals transcriptional signatures of paedomorphic brain development

PubMed Central

2010-01-01

Background The Mexican axolotl (Ambystoma mexicanum) is considered a hopeful monster because it exhibits an adaptive and derived mode of development - paedomorphosis - that has evolved rapidly and independently among tiger salamanders. Unlike related tiger salamanders that undergo metamorphosis, axolotls retain larval morphological traits into adulthood and thus present an adult body plan that differs dramatically from the ancestral (metamorphic) form. The basis of paedomorphic development was investigated by comparing temporal patterns of gene transcription between axolotl and tiger salamander larvae (Ambystoma tigrinum tigrinum) that typically undergo a metamorphosis. Results Transcript abundances from whole brain and pituitary were estimated via microarray analysis on four different days post hatching (42, 56, 70, 84 dph) and regression modeling was used to independently identify genes that were differentially expressed as a function of time in both species. Collectively, more differentially expressed genes (DEGs) were identified as unique to the axolotl (n = 76) and tiger salamander (n = 292) than were identified as shared (n = 108). All but two of the shared DEGs exhibited the same temporal pattern of expression and the unique genes tended to show greater changes later in the larval period when tiger salamander larvae were undergoing anatomical metamorphosis. A second, complementary analysis that directly compared the expression of 1320 genes between the species identified 409 genes that differed as a function of species or the interaction between time and species. Of these 409 DEGs, 84% exhibited higher abundances in tiger salamander larvae at all sampling times. Conclusions Many of the unique tiger salamander transcriptional responses are probably associated with metamorphic biological processes. However, the axolotl also showed unique patterns of transcription early in development. In particular, the axolotl showed a genome-wide reduction in mRNA abundance across loci, including genes that regulate hypothalamic-pituitary activities. This suggests that an axolotls failure to undergo anatomical metamorphosis late in the larval period is indirectly associated with a mechanism(s) that acts earlier in development to broadly program transcription. The axolotl hopeful monster provides a model to identify mechanisms of early brain development that proximally and ultimately affect the expression of adult phenotypes. PMID:20584293

How Metamorphosis Is Different in Plethodontids: Larval Life History Perspectives on Life-Cycle Evolution

PubMed Central

Beachy, Christopher K.; Ryan, Travis J.; Bonett, Ronald M.

2017-01-01

Plethodontid salamanders exhibit biphasic, larval form paedomorphic, and direct developing life cycles. This diversity of developmental strategies exceeds that of any other family of terrestrial vertebrate. Here we compare patterns of larval development among the three divergent lineages of biphasic plethodontids and other salamanders. We discuss how patterns of life-cycle evolution and larval ecology might have produced a wide array of larval life histories. Compared with many other salamanders, most larval plethodontids have relatively slow growth rates and sometimes exceptionally long larval periods (up to 60 mo). Recent phylogenetic analyses of life-cycle evolution indicate that ancestral plethodontids were likely direct developers. If true, then biphasic and paedomorphic lineages might have been independently derived through different developmental mechanisms. Furthermore, biphasic plethodontids largely colonized stream habitats, which tend to have lower productivity than seasonally ephemeral ponds. Consistent with this, plethodontid larvae grow very slowly, and metamorphic timing does not appear to be strongly affected by growth history. On the basis of this, we speculate that feeding schedules and stress hormones might play a comparatively reduced role in governing the timing of metamorphosis of stream-dwelling salamanders, particularly plethodontids. PMID:29269959

Biology and host range of Tecmessa elegans (Lepidoptera: Notodontidae), a leaf-feeding moth evaluated as a potential biological control agent for Schinus terebinthifolius (Sapindales: Anacardiaceae) in the United States.

PubMed

Oleiro, Marina; Mc Kay, Fernando; Wheeler, Gregory S

2011-06-01

During surveys for natural enemies that could be used as classical biological control agents of Schinus terebinthifolius Raddi (Brazilian pepper), the caterpillar, Tecmessa elegans Schaus (Lepidoptera: Notodontidae), was recorded feeding on the leaves of the shrub in South America. The biology and larval and adult host range of this species were examined to determine the insect's suitability for biological control of this invasive weed in North America and Hawaii. Biological observations indicate that the larvae have five instars. When disturbed, the late instar larvae emit formic acid from a prothoracic gland that may protect larvae from generalist predators. Larval host range tests conducted both in South and North America indicated that this species feeds and completes development primarily on members of the Anacardiaceae within the tribe Rhoeae. Oviposition tests indicated that when given a choice in large cages the adults will select the target weed over Pistacia spp. However, considering the many valued plant species in its host range, especially several North American natives, this species will not be considered further for biological control of S. terebinthifolius in North America.

Bombyx mori nucleopolyhedrovirus BM5 protein regulates progeny virus production and viral gene expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kokusho, Ryuhei, E-mail: kokusho@ss.ab.a.u-tokyo.a

2016-11-15

Bombyx mori nucleopolyhedrovirus (BmNPV) orf5 (Bm5) is a core gene of lepidopteran baculoviruses and encodes the protein with the conserved amino acid residues (DUF3627) in its C-terminus. Here, we found that Bm5 disruption resulted in lower titers of budded viruses and fewer numbers of occlusion bodies (OBs) in B. mori cultured cells and larvae, although viral genome replication was not affected. Bm5 disruption also caused aberrant expression of various viral genes at the very late stage of infection. Immunocytochemical analysis revealed that BM5 localized to the nuclear membrane. We also found that DUF3627 is important for OB production, transcriptional regulationmore » of viral genes, and subcellular localization of BM5. Compared with wild-type BmNPV infection, larval death was delayed when B. mori larvae were infected with Bm5 mutants. These results suggest that BM5 is involved in progeny virus production and regulation of viral gene expression at the very late stage of infection. -- Highlights: •The role of BmNPV BM5 protein was examined in B. mori cultured cells and larvae. •BM5 contributes to efficient production of budded viruses and occlusion bodies. •BM5 regulates viral gene expression at the very late stage of infection. •BM5 dominantly localizes to the nuclear membrane. •Bm5 mutant showed v-cath down-regulation and resulting delay of larval death.« less

Preliminary results of the Artemia salina experiments in biostack on LDEF

NASA Technical Reports Server (NTRS)

Graul, E. H.; Ruether, W.; Hiendl, C. O.

1992-01-01

The mosaic egg of the brine shrimp, Artemia salina, resting in blastula or gastrula state represents a system that during further development, proceeds without any further development to the larval stage, the free swimming nauplius. Therefore, injury to a single cell of the egg will be manifest in the larvae. In several experiments, it was shown that the passage of a single heavy ion through the shrimp egg damaged a cellular area large enough to disturb either embryogenesis or further development of the larvae, or the integrity of the adult individual. Emergence from the egg shell was heavily disturbed by the heavy ions as was hatching. Additional late effects, due to a hit by a heavy ion, are delayed of growth and of sexual maturity, and reduced fertility. Anomalies in the body and the extremities could be observed more frequently for the nauplii which had developed from eggs hit by heavy ions.

Effects of arginine vasotocin and mesotocin on the activation and development of amiloride-blockable short-circuit current across larval, adult, and cultured larval bullfrog skins.

PubMed

Takada, Makoto; Fujimaki-Aoba, Kayo; Hokari, Shigeru

2010-03-01

Amphibian skin has osmoregulatory functions, with Na(+) crossing from outside to inside. Na(+) transport can be measured as the short-circuit current (SCC). We investigated the short-term and long-term effects of arginine vasotocin (AVT) and mesotocin (MT) (which modulate Na(+) transport) on the activation and development of an amiloride-blockable SCC (adult-type feature) in larval, adult, and corticoid-cultured larval bullfrog skins. We found: (1) AVT-receptor (AVT-R) and MT-receptor (MT-R) mRNAs could be detected in both larval and adult skins, (2) in the short term (within 60 min), the larval SCC (amiloride-stimulated SCC) was increased by AVT, forskolin, and MT, suggesting that AVT and MT did not activate the inactive ENaC (epithelial sodium channel) protein thought to be expressed in larval skin, (3) in the short term (within 90 min), AVT, forskolin, and MT stimulated the adult SCC (amiloride-blockable SCC), (4) AVT and MT increased both the larval and adult SCC via receptors insensitive to OPC-21268 (an antagonist of the V(1)-type receptor), OPC-31260 (an antagonist of the V(2)-type receptor), and ([d(CH(2))(5),Tyr(Me)(2),Thr(4),Orn(8),des-Gly-NH (2) (9) ]VT) (an antagonist of the oxytocin receptor), (5) culturing EDTA-treated larval skin with corticoids supplemented with AVT (1 microM) or MT (1 microM) for 2 weeks (long-term effects of AVT and MT) did not alter the corticoid-induced development of an amiloride-blockable SCC (adult-type feature). AVT and MT thus have the potential to stimulate SCC though channels that are already expressed, but they may not influence the development of the amiloride-blockable SCC (an adult-type feature) in larval skin.

VARIATION IN GROWTH, LIPID CLASS AND FATTY ACID COMPOSITION OF THE MUD CRAB, RHITHROPANOPEUS HARRISII (GOULD) DURING LARVAL DEVELOPMENT FOLLOWING EXPOSURE TO AN INSECT JUVENILE HORMONE ANALOG (FENOXYCARB(R))

EPA Science Inventory

This study examines the effects of fenoxycarb?, an insect juvenile hormone (JH) analog, on larval growth, and lipid class and fatty acid composition in first crabs of the mud crab Rhithropanopeus harrisii reared through total larval development in nominal water concentrations fr...

VARIATION IN GROWTH, LIPID CLASS AND FATTY ACID COMPOSITION OF THE MUD CRAB, RHITHROPANOPEUS HARRISII (GOULD) DURING LARVAL DEVELOPMENT FOLLOWING EXPOSURE TO AN INSECT JUVENILE HORMONE ANALOG (FENOXYCARB)

EPA Science Inventory

This study examines the effects of fenoxycarb?, an insect juvenile hormone analog, on larval growth, and lipid class and fatty acid composition in first crabs of the mud crab Rhithropanopeus harrisii reared through total larval development in nominal water concentrations from 1 ...

Endoparasitic flies, pollen-collection by bumblebees and a potential host-parasite conflict.

PubMed

Schmid-Hempel, Regula; Schmid-Hempel, Paul

1991-07-01

Conopid flies (Conopidae, Diptera) are common larval parasites of bumblebees. The larva develops inside the abdomen of workers, queens and males. Development is completed within 10-12 days after oviposition when the host is killed and the parasite pupates in situ. Development results in parasitised bees becoming unable to carry large loads of nectar, as the conopid larvae reside where the honey crop is normally located. Furthermore, an addition to the bee's unloaden body mass is likely (average larval weight reached at pupation by the common parasite species Sicus ferrugineus: ±SD 36.3±12.3 mg, n=59; by Physocephala rufipes: 55.8±16.9 mg, n=108). We here asked whether the propensity of workers of the bumblebee Bombus pascuorum to collect nectar rather than pollen is related to the presence of conopid larvae. For samples of bees (n=2254 workers) collected over 3 years of field studies in northwestern Switzerland, there was no difference in the frequency of bees caught as pollen collectors among parasitised (38.1% of cases, n=210) as compared to non-parastised bees (43.9%, n=360) (χ 2 =1.83, n.s.). However, compared to the non-parasitised bees (n=360), those hosts containing a third (last) instar larva (n=9) were less likely to collect pollen than expected by chance χ 2 =6.91, P=0.003. Similarly, hosts with short survival time between capture and being killed by the developing larva (which hence must have harboured a late instar parasite at time of capture) were less likely to collect pollen (8%, n=25) than those found not parasitised (37.6%, n=891 χ 2 =9.16, P<0.001). Late instar larvae grow so big that they fill the entire abdomen. Although there was also a tendency for presumably older bees to collect less pollen, this is unlikely to explain the observations. We also discuss whether these changes in foraging behaviour of bumblebees may reflect a host-parasite conflict over the type of resource to be collected.

Phylogenetic analyses of mode of larval development.

PubMed

Hart, M

2000-12-01

Phylogenies based on morphological or molecular characters have been used to provide an evolutionary context for analysis of larval evolution. Studies of gastropods, bivalves, tunicates, sea stars, sea urchins, and polychaetes have revealed massive parallel evolution of similar larval forms. Some of these studies were designed to test, and have rejected, the species selection hypothesis for evolutionary trends in the frequency of derived larvae or life history traits. However, the lack of well supported models of larval character evolution leave some doubt about the quality of inferences of larval evolution from phylogenies of living taxa. Better models based on maximum likelihood methods and known prior probabilities of larval character state changes will improve our understanding of the history of larval evolution. Copyright 2000 Academic Press.

Developmental Effects of Ocean Acidification Conditions and Elevated Temperature on Homarus Americanus Larvae

NASA Astrophysics Data System (ADS)

Mcveigh, H.; Waller, J. D.

2016-02-01

The Gulf of Maine is experiencing a rapid warming in sea surface temperature and a marked decrease in pH. This study aimed to quantify the impact of elevated temperature and acidification on the larval development of the iconic American lobster (Homarus americanus). Experimental conditions were reflective of current and IPCC predicted levels of temperature and pCO2 to be reached by the end of the century. Larvae were measured for growth (carapace length), development time, and survivorship over the larval duration. Treatments of elevated temperatures experienced decreased development time across the larval stages of H. americanus. Consequently mortality increased at a significantly higher rate under elevated temperature. An increase in larval mortality may decrease recruitment to the commercial fishery, thus impacting the most valuable single species in the state of Maine. Furthermore, experimental pCO2 treatments yielded a significantly decreased development time between larval stages II and III, yet did not have a significant impact on carapace length or mortality. This study indicates that warmer temperatures may have a greater influence than decreased pH on larval development and survival. Determining how this species may respond to changing climactic conditions will better inform the sustainability efforts of such a critical marine fishery.

Mosquito surveillance in the Demilitarized Zone, Republic of Korea, during an outbreak of Plasmodium vivax malaria in 1996 and 1997.

PubMed

Strickman, D; Miller, M E; Kim, H C; Lee, K W

2000-06-01

Since 1993, more than 2,000 cases of vivax malaria have occurred in the Republic of Korea in an epidemic that ended nearly 20 malaria-free years. Most malaria has occurred in the northwestern part of the country, mainly affecting Korean military personnel. As a part of an operational surveillance effort, we sampled mosquitoes in and near the Demilitarized Zone (Paju County, Kyonggi Province) during the last 2 wk of July in 1996 and from May 15 to September 10 in 1997. The 1st year, landing collections were done at 5 different sites; the 2nd year, carbon-dioxide-baited light traps at 5 sites, larval collections in 10 adjacent fields, and landing collections at 1 site in the Demilitarized Zone were performed weekly. Of 17 species collected, Anopheles sinensis was consistently the most abundant mosquito, comprising 79-96% of mosquitoes. The diel pattern of biting by An. sinensis varied by location and season, with the majority of individuals biting late at night during warm weather (>20 degrees C) and early at night during cool weather. In contrast, Aedes vexans nipponii (the 2nd most abundant species) bit in the greatest numbers at the same time all season, from 2000 to 2300 h. Among the correlates with abundance of An. sinensis were average nighttime temperature 2 wk previous to the night in question, wind late at night (negatively correlated), and apparent size of the moon (negatively correlated). The data showed that the exact number of An. sinensis biting could not be estimated from numbers collected in carbon-dioxide-baited light traps. On the other hand, a threshold of 15 An. sinensis per trap night corresponded (88% accuracy) to a threshold of 12 mosquitoes biting 2 adjacent collectors per night. Larval collections were also significantly correlated with landing collections, despite inexact sampling methods and separation of the larval habitat from the site where landing collections were performed. Operational entomology assets using nighttime temperature records, carbon-dioxide-baited light traps, and larval collections should be able to target their efforts in Korea more efficiently.

Larval diet affects mosquito development and permissiveness to Plasmodium infection.

PubMed

Linenberg, Inbar; Christophides, George K; Gendrin, Mathilde

2016-12-02

The larval stages of malaria vector mosquitoes develop in water pools, feeding mostly on microorganisms and environmental detritus. Richness in the nutrient supply to larvae influences the development and metabolism of larvae and adults. Here, we investigated the effects of larval diet on the development, microbiota content and permissiveness to Plasmodium of Anopheles coluzzii. We tested three fish diets often used to rear mosquitoes in the laboratory, including two pelleted diets, Dr. Clarke's Pool Pellets and Nishikoi Fish Pellets, and one flaked diet, Tetramin Fish-Flakes. Larvae grow and develop faster and produce bigger adults when feeding on both types of pellets compared with flakes. This correlates with a higher microbiota load in pellet-fed larvae, in agreement with the known positive effect of the microbiota on mosquito development. Larval diet also significantly influences the prevalence and intensity of Plasmodium berghei infection in adults, whereby Nishikoi Fish Pellets-fed larvae develop into adults that are highly permissive to parasites and survive longer after infection. This correlates with a lower amount of Enterobacteriaceae in the midgut microbiota. Together, our results shed light on the influence of larval feeding on mosquito development, microbiota and vector competence; they also provide useful data for mosquito rearing.

Expression patterns of Eph genes in the "dual visual development" of the lamprey and their significance in the evolution of vision in vertebrates.

PubMed

Suzuki, Daichi G; Murakami, Yasunori; Yamazaki, Yuji; Wada, Hiroshi

2015-01-01

Image-forming vision is crucial to animals for recognizing objects in their environment. In vertebrates, this type of vision is achieved with paired camera eyes and topographic projection of the optic nerve. Topographic projection is established by an orthogonal gradient of axon guidance molecules, such as Ephs. To explore the evolution of image-forming vision in vertebrates, lampreys, which belong to the basal lineage of vertebrates, are key animals because they show unique "dual visual development." In the embryonic and pre-ammocoete larval stage (the "primary" phase), photoreceptive "ocellus-like" eyes develop, but there is no retinotectal optic nerve projection. In the late ammocoete larval stage (the "secondary" phase), the eyes grow and form into camera eyes, and retinotectal projection is newly formed. After metamorphosis, this retinotectal projection in adult lampreys is topographic, similar to that of gnathostomes. In this study, we explored the involvement of Ephs in lamprey "dual visual development" and establishment of the image-form vision. We found that gnathostome-like orthogonal gradient expression was present in the retina during the "secondary" phase; i.e., EphB showed a gradient of expression along the dorsoventral axis, while EphC was expressed along the anteroposterior axis. However, no orthogonal gradient expression was observed during the "primary" phase. These observations suggest that Ephs are likely recruited de novo for the guidance of topographical "second" optic nerve projection. Transformations during lamprey "dual visual development" may represent "recapitulation" from a protochordate-like ancestor to a gnathostome-like vertebrate ancestor. © 2015 Wiley Periodicals, Inc.

Phormidium animalis (Cyanobacteria: Oscillatoriaceae) supports larval development of Anopheles albimanus.

PubMed

Vázquez-Martínez, M Guadalupe; Rodríguez, Mario H; Arredondo-Jiménez, Juan I; Méndez-Sánchez, José D

2003-06-01

The capability of Phormidium animalis, a cyanobacterium commonly found in larval habitats of Anopheles albimanus in southern Mexico, to support larval development of this mosquito was investigated. First-stage larvae were reared under insectary conditions with P. animalis ad libitum and their development was compared with larvae fed with wheat germ. The time of pupation and adult mosquito size, assessed by wing length, were similar in both groups, but fewer adult mosquitoes were obtained from larvae fed with the cyanobacteria. Nevertheless, these observations indicate that P. animalis is ingested and assimilated by larval An. albimanus, making this cyanobacterium a good candidate for genetic engineering for the introduction of mosquitocidal toxins for malaria control in the region.

An analysis of the larval instars of the walnut twig beetle, Pityophthorus juglandis, in northern California black walnut, Juglans hindsii, and a new host record for Hylocurus hirtellus

Treesearch

Paul.L. Dallara; Mary.L. Flint; Steven. J. Seybold

2012-01-01

By measuring and analyzing larval head capsule widths, we determined that a northern California population of the walnut twig beetle, Pityophthorus juglandis Blackman (Coleoptera: Scolytidae), has three larval instars. We also developed rules to classify P. juglandis larval instars. Overlap in the ranges of widths among...

Larval food quantity affects development time, survival and adult biological traits that influence the vectorial capacity of Anopheles darlingi under laboratory conditions.

PubMed

Araújo, Maisa da-Silva; Gil, Luiz Herman S; e-Silva, Alexandre de-Almeida

2012-08-02

The incidence of malaria in the Amazon is seasonal and mosquito vectorial capacity parameters, including abundance and longevity, depend on quantitative and qualitative aspects of the larval diet. Anopheles darlingi is a major malaria vector in the Amazon, representing >95% of total Anopheles population present in the Porto Velho region. Despite its importance in the transmission of the Plasmodium parasite, knowledge of the larval biology and ecology is limited. Studies regarding aspects of adult population ecology are more common than studies on larval ecology. However, in order develop effective control strategies and laboratory breeding conditions for this species, more data on the factors affecting vector biology is needed. The aim of the present study is to assess the effects of larval food quantity on the vectorial capacity of An. darling under laboratory conditions. Anopheles darlingi was maintained at 28°C, 80% humidity and exposed to a daily photoperiod of 12 h. Larvae were divided into three experimental groups that were fed either a low, medium, or high food supply (based on the food amounts consumed by other species of culicids). Each experiment was replicated for six times. A cohort of adults were also exposed to each type of diet and assessed for several biological characteristics (e.g. longevity, bite frequency and survivorship), which were used to estimate the vectorial capacity of each experimental group. The group supplied with higher food amounts observed a reduction in development time while larval survival increased. In addition to enhanced longevity, increasing larval food quantity was positively correlated with increasing frequency of bites, longer blood meal duration and wing length, resulting in greater vectorial capacity. However, females had greater longevity than males despite having smaller wings. Overall, several larval and adult biological traits were significantly affected by larval food availability. Greater larval food supply led to enhance larval and production and larger mosquitoes with longer longevity and higher biting frequency. Thus, larval food availability can alter important biological traits that influence the vectorial capacity of An. darlingi.

Cloning of aquaporin-1 of the blue crab, Callinectes sapidus: its expression during the larval development in hyposalinity.

PubMed

Chung, J Sook; Maurer, Leah; Bratcher, Meagan; Pitula, Joseph S; Ogburn, Matthew B

2012-09-03

Ontogenetic variation in salinity adaptation has been noted for the blue crab, Callinectes sapidus, which uses the export strategy for larval development: females migrate from the estuaries to the coast to spawn, larvae develop in the ocean, and postlarvae (megalopae) colonize estuarine areas. We hypothesized that C. sapidus larvae may be stenohaline and have limited osmoregulatory capacity which compromises their ability to survive in lower salinity waters. We tested this hypothesis using hatchery-raised larvae that were traceable to specific life stages. In addition, we aimed to understand the possible involvement of AQP-1 in salinity adaptation during larval development and during exposure to hyposalinity. A full-length cDNA sequence of aquaporin (GenBank JQ970426) was isolated from the hypodermis of the blue crab, C. sapidus, using PCR with degenerate primers and 5' and 3' RACE. The open reading frame of CasAQP-1 consists of 238 amino acids containing six helical structures and two NPA motifs for the water pore. The expression pattern of CasAQP-1 was ubiquitous in cDNAs from all tissues examined, although higher in the hepatopancreas, thoracic ganglia, abdominal muscle, and hypodermis and lower in the antennal gland, heart, hemocytes, ovary, eyestalk, brain, hindgut, Y-organs, and gill. Callinectes larvae differed in their capacity to molt in hyposalinity, as those at earlier stages from Zoea (Z) 1 to Z4 had lower molting rates than those from Z5 onwards, as compared to controls kept in 30 ppt water. No difference was found in the survival of larvae held at 15 and 30 ppt. CasAQP-1 expression differed with ontogeny during larval development, with significantly higher expression at Z1-2, compared to other larval stages. The exposure to 15 ppt affected larval-stage dependent CasAQP-1 expression which was significantly higher in Z2- 6 stages than the other larval stages. We report the ontogenetic variation in CasAQP-1 expression during the larval development of C. sapidus and the induction of its expression at early larval stages in the exposure of hyposalinity. However, it remains to be determined if the increase in CasAQP-1 expression at later larval stages may have a role in adaptation to hyposalinity.

Exogenous stress hormones alter energetic and nutrient costs of development and metamorphosis.

PubMed

Kirschman, Lucas J; McCue, Marshall D; Boyles, Justin G; Warne, Robin W

2017-09-15

Variation in environmental conditions during larval life stages can shape development during critical windows and have lasting effects on the adult organism. Changes in larval developmental rates in response to environmental conditions, for example, can trade off with growth to determine body size and condition at metamorphosis, which can affect adult survival and fecundity. However, it is unclear how use of energy and nutrients shape trade-offs across life-stage transitions because no studies have quantified these costs of larval development and metamorphosis. We used an experimental approach to manipulate physiological stress in larval amphibians, along with respirometry and 13 C-breath testing to quantify the energetic and nutritional costs of development and metamorphosis. Central to larval developmental responses to environmental conditions is the hypothalamic-pituitary-adrenal/interrenal (HPA/I) axis, which regulates development, as well as energy homeostasis and stress responses across many taxa. Given these pleiotropic effects of HPA/I activity, manipulation of the HPA/I axis may provide insight into costs of metamorphosis. We measured the energetic and nutritional costs across the entire larval period and metamorphosis in a larval amphibian exposed to exogenous glucocorticoid (GC) hormones - the primary hormone secreted by the HPA/I axis. We measured metabolic rates and dry mass across larval ontogeny, and quantified lipid stores and nutrient oxidation via 13 C-breath testing during metamorphosis, under control and GC-exposed conditions. Changes in dry mass match metamorphic states previously reported in the literature, but dynamics of metabolism were influenced by the transition from aquatic to terrestrial respiration. GC-treated larvae had lower dry mass, decreased fat stores and higher oxygen consumption during stages where controls were conserving energy. GC-treated larvae also oxidized greater amounts of 13 C-labelled protein stores. These results provide evidence for a proximate cause of the physiological trade-off between larval growth and development, and provide insight into the energetic and nutrient costs that shape fitness trade-offs across life stages. © 2017. Published by The Company of Biologists Ltd.

Spiroplasma infection causes either early or late male killing in Drosophila, depending on maternal host age

NASA Astrophysics Data System (ADS)

Kageyama, Daisuke; Anbutsu, Hisashi; Shimada, Masakazu; Fukatsu, Takema

2007-04-01

Symbiont-induced male-killing phenotypes have been found in a variety of insects. Conventionally, these phenotypes have been divided into two categories according to the timing of action: early male killing at embryonic stages and late male killing at late larval stages. In Drosophila species, endosymbiotic bacteria of the genus Spiroplasma have been known to cause early male killing. Here, we report that a spiroplasma strain normally causing early male killing also induces late male killing depending on the maternal host age: male-specific mortality of larvae and pupae was more frequently observed in the offspring of young females. As the lowest spiroplasma density and occasional male production were also associated with newly emerged females, we proposed the density-dependent hypothesis for the expression of early and late male-killing phenotypes. Our finding suggested that (1) early and late male-killing phenotypes can be caused by the same symbiont and probably by the same mechanism; (2) late male killing may occur as an attenuated expression of early male killing; (3) expression of early and late male-killing phenotypes may be dependent on the symbiont density, and thus, could potentially be affected by the host immunity and regulation; and (4) early male killing and late male killing could be alternative strategies adopted by microbial reproductive manipulators.

Spatial and temporal variation in distribution of larval lake whitefish in eastern Lake Ontario: signs of recovery?

USGS Publications Warehouse

McKenna, J.E.; Johnson, J. H.

2009-01-01

The lake whitefish (Coregonus clupeaformis) is one of the native Lake Ontario fishes that declined severely over the past century. Recent evidence of larval lake whitefish production in a historic spawning area (Chaumont Bay) might signal a recovery of this species in New York waters. We surveyed coastal and open water areas to evaluate densities and estimate total abundance of larval lake whitefish in Chaumont Bay. Other historic spawning areas and embayments with appropriate spawning and nursery habitat were also surveyed, but only a few larvae were found outside of Chaumont Bay. Lake whitefish larvae were found in every embayment sampled within Chaumont Bay, with larval densities of nearly 600/1000 m2 in some samples. Greatest abundances occurred in the northern sectors and near the mouth of the bay. Open water densities were generally less than half that of nearshore sites. The total bay-wide estimate for 2005 was approximately 644,000 lake whitefish larvae, but dropped to 230,000–400,000 in 2006 and 2007, respectively. Mean larval growth rates (0.36 mm/day) did not differ by year, but were consistently higher in early May than in late April. Lake whitefish production in Chaumont Bay is encouraging for this species, but the cause and persistence of the decline after 2005 can be determined only by continued monitoring. Other possible bottlenecks of survival may exist at juvenile and adult stages and could significantly affect recruitment dynamics. This species is sensitive to normal climatic fluctuations and increased variability associated with global climatic change could make winter nursery conditions unfavorable for this species.

Laboratory trials reveal that exposure to extreme raining events prior to metamorphosis affect the post-settlement performance of an estuarine crab

NASA Astrophysics Data System (ADS)

Rey, Felisa; Silva Neto, Gina M.; Rosa, Rui; Queiroga, Henrique; Calado, Ricardo

2015-03-01

Meteorological forcing can impact planktonic communities, with extreme raining events promoting salinity decreases and triggering larval mortality in estuarine plankton. The present study evaluated how exposure to low salinities prior to metamorphosis of Carcinus maenas megalopae (last larval stage) may affect its ability to metamorphose and the post-metamorphosis performance of juvenile crabs. An extreme raining event that promoted a generalized decrease in salinity (from 25 to 10) in the whole water column of one of the main channels of a coastal lagoon was mimicked in the laboratory. Wild megalopae of C. maenas were collected and kept individually without any food at salinities of 10 or 25 (S10 or S25) until they either died or metamorphosed to the first crab instar (C1). Specimens metamorphosing in 5 days or less following their collection were labeled as early settlers (ES10 and ES25), while those taking more than 5 days were labeled as late settlers (LS10 and LS25). All newly metamorphosed crabs were kept individually until C5 at a salinity of 25 and fed ad libitum, with their intermolt periods and carapace width (CW) being recorded. Osmotic stress did not affect the survival or ability to metamorphose of C. maenas megalopae, with 89% of all larvae in both salinities being able to metamorphose. This result is supported by the ability of this larval stage to hyper-regulate. Nonetheless, an exposure of late settling megalopae to low salinities prior to metamorphosis promotes the occurrence of juvenile crabs with a smaller CW. The deleterious effects of exposing late settling megalopae to low salinities appears to be magnified during early benthic life, with C5 originating from treatment LS10 displaying a significantly smaller CW (4.87 ± 0.28 mm) and lower wet weight (WW) (28.95 ± 4.62 mg). On the other side, C5 originating from ES25 exhibited a significantly higher CW (5.90 ± 0.33 mm) and WW (50.89 ± 8.14 mg). The nutritional vulnerability experienced by megalopae starved for longer periods (late settlers) may have been magnified for specimens exposed to a lower salinity, with the energetic costs associated with hyper-regulation negatively affecting the growth performance of juvenile crabs. Osmotic stress experienced by late settling megalopae can shape adult populations of C. maenas by promoting the occurrence of smaller juveniles, thus more vulnerable to predation and cannibalism. Phenotypic links must be incorporated in the study of marine invertebrates, namely when life stages are vulnerable to metereological forcing (e.g., extreme rainfall) at critical periods of their life-cycle (e.g., metamorphosis).

[Biological cycle of Cyrnea (Procyrnea) mansoni Seurat, 1914, a habronemid nematode parasite of birds of prey in Togo].

PubMed

Quentin, J C; Seureau, C; Railhac, C

1983-01-01

A habronemid nematode in birds of prey, Milvus migrans Bonaparti and Accipiter badius Linné, in Togo, is identified as Cyrnea (Procyrnea) mansioni (Seurat, 1914). Larval development is experimentally studied in the orthopteran Acrididae Tylotropidius patagiatus Karsch. The first three larval stages are described and illustrated. The biology of this spiruroid nematode is distinguished by the unusual rapidity of larval development (infective larvae at 10 days). Comparison of the life cycle of C. mansioni with life cycles of other Habronemid Nematodes parasitizing birds, points out an evolution of larvae from primitive forms of large size and slow development to evolved forms of small size and rapid development. Observations concerning the encapsulation of infective larvae in the intermediate host confirm this larval evolution.

Bacterial microbiota assemblage in Aedes albopictus mosquitoes and its impacts on larval development.

PubMed

Wang, Xiaoming; Liu, Tong; Wu, Yang; Zhong, Daibin; Zhou, Guofa; Su, Xinghua; Xu, Jiabao; Sotero, Charity F; Sadruddin, Adnan A; Wu, Kun; Chen, Xiao-Guang; Yan, Guiyun

2018-05-30

Interactions between bacterial microbiota and mosquitoes play an important role in mosquitoes' capacity to transmit pathogens. However, microbiota assemblages within mosquitoes and the impact of microbiota in environments on mosquito development and survival remain unclear. This study examined microbiota assemblages and the effects of aquatic environment microbiota on the larval development of the Aedes albopictus mosquito, an important dengue virus vector. Life table studies have found that reducing bacterial load in natural aquatic habitats through water filtering and treatment with antibiotics significantly reduced the larva-to-adult emergence rate. This finding was consistent in two types of larval habitats examined-discarded tires and flowerpots, suggesting that bacteria play a crucial role in larval development. Pyrosequencing of the bacterial 16S rRNA gene was used to determine the diversity of bacterial communities in larval habitats and the resulting numbers of mosquitoes under both laboratory and field conditions. The microbiota profiling identified common shared bacteria among samples from different years; further studies are needed to determine whether these bacteria represent a core microbiota. The highest microbiota diversity was found in aquatic habitats, followed by mosquito larvae, and the lowest in adult mosquitoes. Mosquito larvae ingested their bacterial microbiota and nutrients from aquatic habitats of high microbiota diversity. Taken together, the results support the observation that Ae. albopictus larvae are able to utilize diverse bacteria from aquatic habitats and that live bacteria from aquatic habitats play an important role in larval mosquito development and survival. These findings provide new insights into bacteria's role in mosquito larval ecology. © 2018 John Wiley & Sons Ltd.

[BIO-INSECTICIDAL ACTIVITY OF ALPINIA GALANGA (L.) ON LARVAL DEVELOPMENT OF SPODOPTERA LITURA (LEPIDOPTERA: NOCTUIDAE).

PubMed

Pumchan, A; Puangsomchit, A; Temyarasilp, P; Pluempanupat, W; Bullangpoti, V

2015-01-01

The aim of the study was to assess the bio-efficacy of four Alpinia galanga rhizome crude extracts against the second and third instars of Spodoptera litura, an important field pest. The growth of younger larvae was significantly affected while that of the older larval stage was less influenced. In both stages, the methanol crude extract showed the greatest efficiency which caused the highest number of abnormal adults to occur and produced a large LD₅₀ value (12.816 µg/ larvae) pupicidal percentage after treatment, whereas, hexane extract caused the highest mortality during the larval-pupal stage after treatment with an LD₅₀ value of 6.354 µg/ larvae. However, the larval development was not significantly different among all treated larvae compared to the control. This study suggests that secondary larval instars of S. litura are more susceptible to the larval growth inhibitory action of Alpinia galanga extracts and these extracts could also be applied for use in the management of pests.

Methods for conducting bioassays using embryos and larvae of Pacific herring, Clupea pallasi.

PubMed

Dinnel, Paul A; Middaugh, Douglas P; Schwarck, Nathan T; Farren, Heather M; Haley, Richard K; Hoover, Richard A; Elphick, James; Tobiason, Karen; Marshall, Randall R

2011-02-01

The rapid decrease of several stocks of Pacific herring, Clupea pallasi, in Puget Sound, Washington, has led to concerns about the effects of industrial and nonpoint source contamination on the embryo and larval stages of this and related forage fish species. To address these concerns, the state of Washington and several industries have funded efforts to develop embryo and larval bioassay protocols that can be used by commercial laboratories for routine effluent testing. This article presents the results of research to develop herring embryo and larval bioassay protocols. Factors evaluated during protocol development included temperature, salinity, dissolved oxygen (DO), light intensity, photoperiod, larval feeding regimes, use of brine and artificial sea salts, gonad sources, collection methods, and egg quality.

Gene expression patterns during the larval development of European sea bass (dicentrarchus labrax) by microarray analysis.

PubMed

Darias, M J; Zambonino-Infante, J L; Hugot, K; Cahu, C L; Mazurais, D

2008-01-01

During the larval period, marine teleosts undergo very fast growth and dramatic changes in morphology, metabolism, and behavior to accomplish their metamorphosis into juvenile fish. Regulation of gene expression is widely thought to be a key mechanism underlying the management of the biological processes required for harmonious development over this phase of life. To provide an overall analysis of gene expression in the whole body during sea bass larval development, we monitored the expression of 6,626 distinct genes at 10 different points in time between 7 and 43 days post-hatching (dph) by using heterologous hybridization of a rainbow trout cDNA microarray. The differentially expressed genes (n = 485) could be grouped into two categories: genes that were generally up-expressed early, between 7 and 23 dph, and genes up-expressed between 25 and 43 dph. Interestingly, among the genes regulated during the larval period, those related to organogenesis, energy pathways, biosynthesis, and digestion were over-represented compared with total set of analyzed genes. We discuss the quantitative regulation of whole-body contents of these specific transcripts with regard to the ontogenesis and maturation of essential functions that take place over larval development. Our study is the first utilization of a transcriptomic approach in sea bass and reveals dynamic changes in gene expression patterns in relation to marine finfish larval development.

Weather, hydroregime, and breeding effort influence juvenile recruitment of anurans: implications for climate change

DOE PAGES

Greenberg, C. H.; Zarnoch, S. J.; Austin, J. D.

2017-05-03

Amphibians that primarily breed in ephemeral wetlands are especially vulnerable to climate change because they rely on rainfall or temperature to initiate breeding and create suitable hydroregimes (water duration, timing, frequency, depth) for reproductive success. Hydroregime effects on reproductive success are likely to differ among species because of differences in reproductive strategies: the length and timing of breeding period, rate of larval development, and timing of metamorphosis. We applied an information-theoretic approach to 22 consecutive years of continuous amphibian trapping data at eight ephemeral wetlands to test hypotheses regarding environmental (hydroregime, weather) and biological (adult breeding effort) factors affecting juvenilemore » recruitment (JR) by six focal species representing four reproductive strategies. We hypothesized that (1) JR by species with similar reproductive strategies would be influenced by similar variables; (2) JR would be higher for all species when models encompassed the maximum time span of potential tadpole occurrence and development; and (3) JR rates within individual wetlands and breeding cycles would correlate most closely between species with similar breeding strategies. The best model for all focal species (except Scaphiopus holbrookii) encompassed the maximum time span and indicated that ≥1 hydroregime variable, total precipitation, or both were important drivers of reproductive success; average air temperature was not. Continuous hydroperiod through peak juvenile emigration was an important predictor of JR for species with prolonged breeding periods, slow larval development, and a “fixed” late spring start date for juvenile emigration (regardless of when oviposition occurred, or cohort age; Lithobates capito, Lithobates sphenocephalus), but not for species with rapid larval development and continual emigration as cohorts complete metamorphosis ( Anaxyrus terrestris, Anaxyrus quercicus, Gastrophryne carolinensis, S. holbrookii). Total rainfall was positively associated with recruitment for most species; depth characteristics affected species differently. Annual JR was positively correlated among species with similar reproductive strategies. Our results indicate that weather and hydroregime characteristics interact with reproductive strategies that differ among amphibian species and influence reproductive plasticity, opportunity, and success. In conclusion, effects of altered weather patterns associated with climate change on amphibian reproductive success may correspond more closely among species having similar reproductive strategies, with critical implications for population trends and assemblages.« less

Weather, hydroregime, and breeding effort influence juvenile recruitment of anurans: implications for climate change

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenberg, C. H.; Zarnoch, S. J.; Austin, J. D.

Amphibians that primarily breed in ephemeral wetlands are especially vulnerable to climate change because they rely on rainfall or temperature to initiate breeding and create suitable hydroregimes (water duration, timing, frequency, depth) for reproductive success. Hydroregime effects on reproductive success are likely to differ among species because of differences in reproductive strategies: the length and timing of breeding period, rate of larval development, and timing of metamorphosis. We applied an information-theoretic approach to 22 consecutive years of continuous amphibian trapping data at eight ephemeral wetlands to test hypotheses regarding environmental (hydroregime, weather) and biological (adult breeding effort) factors affecting juvenilemore » recruitment (JR) by six focal species representing four reproductive strategies. We hypothesized that (1) JR by species with similar reproductive strategies would be influenced by similar variables; (2) JR would be higher for all species when models encompassed the maximum time span of potential tadpole occurrence and development; and (3) JR rates within individual wetlands and breeding cycles would correlate most closely between species with similar breeding strategies. The best model for all focal species (except Scaphiopus holbrookii) encompassed the maximum time span and indicated that ≥1 hydroregime variable, total precipitation, or both were important drivers of reproductive success; average air temperature was not. Continuous hydroperiod through peak juvenile emigration was an important predictor of JR for species with prolonged breeding periods, slow larval development, and a “fixed” late spring start date for juvenile emigration (regardless of when oviposition occurred, or cohort age; Lithobates capito, Lithobates sphenocephalus), but not for species with rapid larval development and continual emigration as cohorts complete metamorphosis ( Anaxyrus terrestris, Anaxyrus quercicus, Gastrophryne carolinensis, S. holbrookii). Total rainfall was positively associated with recruitment for most species; depth characteristics affected species differently. Annual JR was positively correlated among species with similar reproductive strategies. Our results indicate that weather and hydroregime characteristics interact with reproductive strategies that differ among amphibian species and influence reproductive plasticity, opportunity, and success. In conclusion, effects of altered weather patterns associated with climate change on amphibian reproductive success may correspond more closely among species having similar reproductive strategies, with critical implications for population trends and assemblages.« less

Coordinated metabolic transitions during Drosophila embryogenesis and the onset of aerobic glycolysis.

PubMed

Tennessen, Jason M; Bertagnolli, Nicolas M; Evans, Janelle; Sieber, Matt H; Cox, James; Thummel, Carl S

2014-03-12

Rapidly proliferating cells such as cancer cells and embryonic stem cells rely on a specialized metabolic program known as aerobic glycolysis, which supports biomass production from carbohydrates. The fruit fly Drosophila melanogaster also utilizes aerobic glycolysis to support the rapid growth that occurs during larval development. Here we use singular value decomposition analysis of modENCODE RNA-seq data combined with GC-MS-based metabolomic analysis to analyze the changes in gene expression and metabolism that occur during Drosophila embryogenesis, spanning the onset of aerobic glycolysis. Unexpectedly, we find that the most common pattern of co-expressed genes in embryos includes the global switch to glycolytic gene expression that occurs midway through embryogenesis. In contrast to the canonical aerobic glycolytic pathway, however, which is accompanied by reduced mitochondrial oxidative metabolism, the expression of genes involved in the tricarboxylic cycle (TCA cycle) and the electron transport chain are also upregulated at this time. Mitochondrial activity, however, appears to be attenuated, as embryos exhibit a block in the TCA cycle that results in elevated levels of citrate, isocitrate, and α-ketoglutarate. We also find that genes involved in lipid breakdown and β-oxidation are upregulated prior to the transcriptional initiation of glycolysis, but are downregulated before the onset of larval development, revealing coordinated use of lipids and carbohydrates during development. These observations demonstrate the efficient use of nutrient stores to support embryonic development, define sequential metabolic transitions during this stage, and demonstrate striking similarities between the metabolic state of late-stage fly embryos and tumor cells. Copyright © 2014 Tennessen et al.

Solar irradiance dictates settlement timing and intensity of marine mussels

PubMed Central

Fuentes-Santos, Isabel; Labarta, Uxío; Álvarez-Salgado, X. Antón; Fernández-Reiriz, Mª José

2016-01-01

Identifying the environmental factors driving larval settlement processes is crucial to understand the population dynamics of marine invertebrates. This work aims to go a step ahead and predict larval presence and intensity. For this purpose we consider the influence of solar irradiance, wind regime and continental runoff on the settlement processes. For the first time, we conducted a 5-years weekly monitoring of Mytilus galloprovincialis settlement on artificial suspended substrates, which allowed us to search for interannual variability in the settlement patterns. Comparison between the seasonal pattern of larval settlement and solar irradiance, as well as the well-known effect of solar irradiance on water temperature and food availability, suggest that solar irradiance indirectly influences the settlement process, and support the use of this meteorological variable to predict settlement occurrence. Our results show that solar irradiance allows predicting the beginning and end of the settlement cycle a month in advance: Particularly we have observed that solar irradiance during late winter indirectly drives the timing and intensity of the settlement onset, Finally, a functional generalise additive model, which considers the influence of solar irradiance and continental runoff on the settlement process, provides an accurate prediction of settlement intensity a fortnight in advance. PMID:27384527

Late-instar Behavior of Aedes aegypti (Diptera: Culicidae) Larvae in Different Thermal and Nutritive Environments.

PubMed

Reiskind, Michael H; Janairo, M Shawn

2015-09-01

The effects of temperature on ectotherm growth have been well documented. How temperature affects foraging behavior is less well explored, and has not been studied in larval mosquitoes. We hypothesized that temperature changes foraging behavior in the aquatic larval phase of the mosquito, Aedes aegypti L. Based on empirical results in other systems, we predicted that foraging effort would increase at higher temperatures in these insects. We tested this prediction over three temperature conditions at two food levels. We measured behaviors by video recording replicated cohorts of fourth-instar mosquitoes and assessing individual behavior and time budgets using an ethogram. We found both food level and temperature had significant impacts on larval foraging behavior, with more time spent actively foraging at low food levels and at low temperatures, and more occurrences of active foraging at both temperature extremes. These results are contrary to some of our predictions, but fit into theoretical responses to temperature based upon dynamic energy budget models. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Solar irradiance dictates settlement timing and intensity of marine mussels

NASA Astrophysics Data System (ADS)

Fuentes-Santos, Isabel; Labarta, Uxío; Álvarez-Salgado, X. Antón; Fernández-Reiriz, Mª José

2016-07-01

Identifying the environmental factors driving larval settlement processes is crucial to understand the population dynamics of marine invertebrates. This work aims to go a step ahead and predict larval presence and intensity. For this purpose we consider the influence of solar irradiance, wind regime and continental runoff on the settlement processes. For the first time, we conducted a 5-years weekly monitoring of Mytilus galloprovincialis settlement on artificial suspended substrates, which allowed us to search for interannual variability in the settlement patterns. Comparison between the seasonal pattern of larval settlement and solar irradiance, as well as the well-known effect of solar irradiance on water temperature and food availability, suggest that solar irradiance indirectly influences the settlement process, and support the use of this meteorological variable to predict settlement occurrence. Our results show that solar irradiance allows predicting the beginning and end of the settlement cycle a month in advance: Particularly we have observed that solar irradiance during late winter indirectly drives the timing and intensity of the settlement onset, Finally, a functional generalise additive model, which considers the influence of solar irradiance and continental runoff on the settlement process, provides an accurate prediction of settlement intensity a fortnight in advance.

VARIATIONS IN LARVAL GROWTH AND METABOLISM OF AN ESTUARINE SHRIMP DURING TOXICOSIS BY AN INSECT GROWTH REGULATOR

EPA Science Inventory

Exposure of the estuarine shrimp, Ptiaemonetes pugio, to a juvenile hormone analogue (> 3 ug methoprene-1) throughout larval development inhibited successful completion of metamorphosis. Methoprene exposure retarded growth in early larval stages and postlarvae enhanced growth in ...

Jaw muscle development as evidence for embryonic repatterning in direct-developing frogs.

PubMed Central

Hanken, J; Klymkowsky, M W; Alley, K E; Jennings, D H

1997-01-01

The Puerto Rican direct-developing frog Eleutherodactylus coqui (Leptodactylidae) displays a novel mode of jaw muscle development for anuran amphibians. Unlike metamorphosing species, several larval-specific features never form in E. coqui; embryonic muscle primordia initially assume an abbreviated, mid-metamorphic configuration that is soon remodelled to form the adult morphology before hatching. Also lacking are both the distinct population of larval myofibres and the conspicuous, larval-to-adult myofibre turnover that are characteristic of muscle development in metamorphosing species. These modifications are part of a comprehensive alteration in embryonic cranial patterning that has accompanied life history evolution in this highly speciose lineage. Embryonic 'repatterning' in Eleutherodactylus may reflect underlying developmental mechanisms that mediate the integrated evolution of complex structures. Such mechanisms may also facilitate, in organisms with a primitively complex life cycle, the evolutionary dissociation of embryonic, larval, and adult features. PMID:9332017

Soundscapes and Larval Settlement: Characterizing the Stimulus from a Larval Perspective.

PubMed

Lillis, Ashlee; Eggleston, David B; Bohnenstiehl, DelWayne R

2016-01-01

There is growing evidence that underwater sounds serve as a cue for the larvae of marine organisms to locate suitable settlement habitats; however, the relevant spatiotemporal scales of variability in habitat-related sounds and how this variation scales with larval settlement processes remain largely uncharacterized, particularly in estuarine habitats. Here, we provide an overview of the approaches we have developed to characterize an estuarine soundscape as it relates to larval processes, and a conceptual framework is provided for how habitat-related sounds may influence larval settlement, using oyster reef soundscapes as an example.

Comparative analysis of Met-enkephalin, galanin and GABA immunoreactivity in the developing trout preoptic-hypophyseal system.

PubMed

Rodríguez Díaz, M A; Candal, E; Santos-Durán, G N; Adrio, F; Rodríguez-Moldes, I

2011-08-01

We studied the organization of Met-enkephalin-containing cells and fibers in the developing preoptic-hypophyseal system of the brown trout (Salmo trutta fario) by immunohistochemistry and determined the relationship of these cells and fibers to the galaninergic and GABAergic systems. Met-enkephalin immunoreactivity was observed in cells in the preoptic area, the hypothalamus and the pituitary of late larvae. In the hypophysis, a few Met-enkephalin-containing cells were present in all divisions of the adenohypophysis, and some immunoreactive fibers were present in the interdigitations of the neural lobe with the proximal pars distalis. Concurrently, GABAergic fibers innervated the anterior and posterior neural lobe. Galanin cells coexisted with Met-enkephalin cells in neuronal groups of the preoptic-hypophyseal system. Galaninergic and GABAergic fibers innervated the preoptic and hypothalamic areas, but GABAergic fibers containing galanin were not observed. These results indicate that Met-enkephalin, galanin and GABA may modulate neuroendocrine activities in the preoptic area, hypothalamus and pituitary during the transition from larval to juvenile period. To better know how the development of the trout preoptic-hypophyseal system takes place, we studied the patterns of cell proliferation and expression of Pax6, a conserved transcription factor involved in the hypophysis development. Pax6 expressing cells and proliferating cells were present in the Rathke's pouch, the hypothalamus and the hypophysis of early larvae. In late larvae, Pax6 expression was no longer observed in these areas, and the density of proliferating cells largely decreased throughout development, although they remained in the hypophysis of late larvae and juveniles, suggesting that Pax6 might play an important role in the early regionalization of the pituitary in the trout. Copyright © 2011 Elsevier Inc. All rights reserved.

Relationships of abscised cotton fruit to boll weevil (Coleoptera: Curculionidae) feeding, oviposition, and development.

PubMed

Showler, Allan T

2008-02-01

Abscised cotton, Gossypium hirsutum L., fruit in field plots planted at different times were examined to assess adult boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), use of squares and bolls during 2002 and 2003 in the Lower Rio Grande Valley of Texas. Although boll abscission is not necessarily related to infestation, generally more bolls abscised than squares and abundances of fallen bolls were not related to the planting date treatments. During 2003, fallen squares were most abundant in the late-planted treatment. Although large squares (5.5-8-mm-diameter) on the plant are preferred for boll weevil oviposition, diameter of abscised squares is not a reliable measurement because of shrinkage resulting from desiccation and larval feeding. Fallen feeding-punctured squares and bolls were most abundant in late plantings but differences between fallen feeding-punctured squares versus fallen feeding-punctured bolls were found in only one treatment in 2003. During the same year, fallen oviposition-punctured squares were more numerous in the late-planted treatment than in the earlier treatments. Treatment effects were not found on numbers of oviposition-punctured bolls, but fallen oviposition-punctured squares were more common than bolls in the late-planted treatment compared with earlier treatments each year. Dead weevil eggs, larvae, and pupae inside fallen fruit were few and planting date treatment effects were not detected. Living third instars and pupae were more abundant in fallen squares of the late-planted treatment than in the earlier treatments and bolls of all three treatments. This study shows that fallen squares in late-planted cotton contribute more to adult boll weevil populations than bolls, or squares of earlier plantings.

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Arca inflata Reeve

NASA Astrophysics Data System (ADS)

Li, Jiaqi; Jiang, Zengjie; Zhang, Jihong; Mao, Yuze; Bian, Dapeng; Fang, Jianguang

2014-11-01

We evaluated the effect of pH on larval development in larval Pacific oyster ( Crassostrea gigas) and blood cockle ( Arca inflata Reeve). The larvae were reared at pH 8.2 (control), 7.9, 7.6, or 7.3 beginning 30 min or 24 h post fertilization. Exposure to lower pH during early embryonic development inhibited larval shell formation in both species. Compared with the control, larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3. Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3. However, when exposure was delayed until 24 h post fertilization, shell formation was only inhibited in blood cockle larvae reared at pH 7.3. Thus, the early embryonic stages were more sensitive to acidified conditions. Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves. Although the effects appear subtle, they may accumulate and lead to subsequent issues during later larval development.

Does Skipping a Meal Matter to a Butterfly's Appearance? Effects of Larval Food Stress on Wing Morphology and Color in Monarch Butterflies

PubMed Central

Johnson, Haley; Solensky, Michelle J.; Satterfield, Dara A.; Davis, Andrew K.

2014-01-01

In animals with complex life cycles, all resources needed to form adult tissues are procured at the larval stage. For butterflies, the proper development of wings involves synthesizing tissue during metamorphosis based on the raw materials obtained by larvae. Similarly, manufacture of pigment for wing scales also requires resources acquired by larvae. We conducted an experiment to test the effects of food deprivation in the larval stage on multiple measures of adult wing morphology and coloration of monarch butterflies (Danaus plexippus), a species in which long-distance migration makes flight efficiency critical. In a captive setting, we restricted food (milkweed) from late-stage larvae for either 24 hrs or 48 hrs, then after metamorphosis we used image analysis methods to measure forewing surface area and elongation (length/width), which are both important for migration. We also measured the brightness of orange pigment and the intensity of black on the wing. There were correlations between several wing features, including an unexpected association between wing elongation and melanism, which will require further study to fully understand. The clearest effect of food restriction was a reduction in adult wing size in the high stress group (by approximately 2%). Patterns observed for other wing traits were ambiguous: monarchs in the low stress group (but not the high) had less elongated and paler orange pigmentation. There was no effect on wing melanism. Although some patterns obtained in this study were unclear, our results concerning wing size have direct bearing on the monarch migration. We show that if milkweed is limited for monarch larvae, their wings become stunted, which could ultimately result in lower migration success. PMID:24695643

Does skipping a meal matter to a butterfly's appearance? Effects of larval food stress on wing morphology and color in monarch butterflies.

PubMed

Johnson, Haley; Solensky, Michelle J; Satterfield, Dara A; Davis, Andrew K

2014-01-01

In animals with complex life cycles, all resources needed to form adult tissues are procured at the larval stage. For butterflies, the proper development of wings involves synthesizing tissue during metamorphosis based on the raw materials obtained by larvae. Similarly, manufacture of pigment for wing scales also requires resources acquired by larvae. We conducted an experiment to test the effects of food deprivation in the larval stage on multiple measures of adult wing morphology and coloration of monarch butterflies (Danaus plexippus), a species in which long-distance migration makes flight efficiency critical. In a captive setting, we restricted food (milkweed) from late-stage larvae for either 24 hrs or 48 hrs, then after metamorphosis we used image analysis methods to measure forewing surface area and elongation (length/width), which are both important for migration. We also measured the brightness of orange pigment and the intensity of black on the wing. There were correlations between several wing features, including an unexpected association between wing elongation and melanism, which will require further study to fully understand. The clearest effect of food restriction was a reduction in adult wing size in the high stress group (by approximately 2%). Patterns observed for other wing traits were ambiguous: monarchs in the low stress group (but not the high) had less elongated and paler orange pigmentation. There was no effect on wing melanism. Although some patterns obtained in this study were unclear, our results concerning wing size have direct bearing on the monarch migration. We show that if milkweed is limited for monarch larvae, their wings become stunted, which could ultimately result in lower migration success.

Stage-Specific Changes in Physiological and Life-History Responses to Elevated Temperature and Pco2 during the Larval Development of the European Lobster Homarus gammarus (L.).

PubMed

Small, Daniel P; Calosi, Piero; Boothroyd, Dominic; Widdicombe, Steve; Spicer, John I

2015-01-01

An organism's physiological processes form the link between its life-history traits and the prevailing environmental conditions, especially in species with complex life cycles. Understanding how these processes respond to changing environmental conditions, thereby affecting organismal development, is critical if we are to predict the biological implications of current and future global climate change. However, much of our knowledge is derived from adults or single developmental stages. Consequently, we investigated the metabolic rate, organic content, carapace mineralization, growth, and survival across each larval stage of the European lobster Homarus gammarus, reared under current and predicted future ocean warming and acidification scenarios. Larvae exhibited stage-specific changes in the temperature sensitivity of their metabolic rate. Elevated Pco2 increased C∶N ratios and interacted with elevated temperature to affect carapace mineralization. These changes were linked to concomitant changes in survivorship and growth, from which it was concluded that bottlenecks were evident during H. gammarus larval development in stages I and IV, the transition phases between the embryonic and pelagic larval stages and between the larval and megalopa stages, respectively. We therefore suggest that natural changes in optimum temperature during ontogeny will be key to larvae survival in a future warmer ocean. The interactions of these natural changes with elevated temperature and Pco2 significantly alter physiological condition and body size of the last larval stage before the transition from a planktonic to a benthic life style. Thus, living and growing in warm, hypercapnic waters could compromise larval lobster growth, development, and recruitment.

Contributions of Anopheles larval control to malaria suppression in tropical Africa: review of achievements and potential.

PubMed

Walker, K; Lynch, M

2007-03-01

Malaria vector control targeting the larval stages of mosquitoes was applied successfully against many species of Anopheles (Diptera: Culicidae) in malarious countries until the mid-20th Century. Since the introduction of DDT in the 1940s and the associated development of indoor residual spraying (IRS), which usually has a more powerful impact than larval control on vectorial capacity, the focus of malaria prevention programmes has shifted to the control of adult vectors. In the Afrotropical Region, where malaria is transmitted mainly by Anopheles funestus Giles and members of the Anopheles gambiae Giles complex, gaps in information on larval ecology and the ability of An. gambiae sensu lato to exploit a wide variety of larval habitats have discouraged efforts to develop and implement larval control strategies. Opportunities to complement adulticiding with other components of integrated vector management, along with concerns about insecticide resistance, environmental impacts, rising costs of IRS and logistical constraints, have stimulated renewed interest in larval control of malaria vectors. Techniques include environmental management, involving the temporary or permanent removal of anopheline larval habitats, as well as larviciding with chemical or biological agents. This present review covers large-scale trials of anopheline larval control methods, focusing on field studies in Africa conducted within the past 15 years. Although such studies are limited in number and scope, their results suggest that targeting larvae, particularly in human-made habitats, can significantly reduce malaria transmission in appropriate settings. These approaches are especially suitable for urban areas, where larval habitats are limited, particularly when applied in conjunction with IRS and other adulticidal measures, such as the use of insecticide treated bednets.

Cross-shore and Vertical Distributions of Invertebrate Larvae Using Autonomous Sampling Coupled with Genetic Analysis

NASA Astrophysics Data System (ADS)

Govindarajan, A.; Pineda, J.; Purcell, M.; Tradd, K.; Packard, G.; Girard, A.; Dennett, M.; Breier, J. A., Jr.

2016-02-01

We present a new method to estimate the distribution of invertebrate larvae relative to environmental variables such as temperature, salinity, and circulation. A large volume in situ filtering system developed for discrete biogeochemical sampling in the deep-sea (the Suspended Particulate Rosette "SUPR" multisampler) was mounted to the autonomous underwater vehicle REMUS 600 for coastal larval and environmental sampling. We describe the results of SUPR-REMUS deployments conducted in Buzzards Bay, Massachusetts (2014) and west of Martha's Vineyard, Massachusetts (2015). We collected discrete samples cross-shore and from surface, middle, and bottom layers of the water column. Samples were preserved for DNA analysis. Our Buzzards Bay deployment targeted barnacle larvae, which are abundant in late winter and early spring. For these samples, we used morphological analysis and DNA barcodes generated by Sanger sequencing to obtain stage and species-specific cross-shore and vertical distributions. We targeted bivalve larvae in our 2015 deployments, and genetic analysis of larvae from these samples is underway. For these samples, we are comparing species barcode data derived from traditional Sanger sequencing of individuals to those obtained from next generation sequencing (NGS) of bulk plankton samples. Our results demonstrate the utility of autonomous sampling combined with DNA barcoding for studying larval distributions and transport dynamics.

A model of muscle atrophy based on live microscopy of muscle remodelling in Drosophila metamorphosis.

PubMed

Kuleesha, Yadav; Puah, Wee Choo; Wasser, Martin

2016-02-01

Genes controlling muscle size and survival play important roles in muscle wasting diseases. In Drosophila melanogaster metamorphosis, larval abdominal muscles undergo two developmental fates. While a doomed population is eliminated by cell death, another persistent group is remodelled and survives into adulthood. To identify and characterize genes involved in the development of remodelled muscles, we devised a workflow consisting of in vivo imaging, targeted gene perturbation and quantitative image analysis. We show that inhibition of TOR signalling and activation of autophagy promote developmental muscle atrophy in early, while TOR and yorkie activation are required for muscle growth in late pupation. We discovered changes in the localization of myonuclei during remodelling that involve anti-polar migration leading to central clustering followed by polar migration resulting in localization along the midline. We demonstrate that the Cathepsin L orthologue Cp1 is required for myonuclear clustering in mid, while autophagy contributes to central positioning of nuclei in late metamorphosis. In conclusion, studying muscle remodelling in metamorphosis can provide new insights into the cell biology of muscle wasting.

A model of muscle atrophy based on live microscopy of muscle remodelling in Drosophila metamorphosis

PubMed Central

Kuleesha, Yadav; Puah, Wee Choo; Wasser, Martin

2016-01-01

Genes controlling muscle size and survival play important roles in muscle wasting diseases. In Drosophila melanogaster metamorphosis, larval abdominal muscles undergo two developmental fates. While a doomed population is eliminated by cell death, another persistent group is remodelled and survives into adulthood. To identify and characterize genes involved in the development of remodelled muscles, we devised a workflow consisting of in vivo imaging, targeted gene perturbation and quantitative image analysis. We show that inhibition of TOR signalling and activation of autophagy promote developmental muscle atrophy in early, while TOR and yorkie activation are required for muscle growth in late pupation. We discovered changes in the localization of myonuclei during remodelling that involve anti-polar migration leading to central clustering followed by polar migration resulting in localization along the midline. We demonstrate that the Cathepsin L orthologue Cp1 is required for myonuclear clustering in mid, while autophagy contributes to central positioning of nuclei in late metamorphosis. In conclusion, studying muscle remodelling in metamorphosis can provide new insights into the cell biology of muscle wasting. PMID:26998322

Acidification reduced growth rate but not swimming speed of larval sea urchins.

PubMed

Chan, Kit Yu Karen; García, Eliseba; Dupont, Sam

2015-05-15

Swimming behaviors of planktonic larvae impact dispersal and population dynamics of many benthic marine invertebrates. This key ecological function is modulated by larval development dynamics, biomechanics of the resulting morphology, and behavioral choices. Studies on ocean acidification effects on larval stages have yet to address this important interaction between development and swimming under environmentally-relevant flow conditions. Our video motion analysis revealed that pH covering present and future natural variability (pH 8.0, 7.6 and 7.2) did not affect age-specific swimming of larval green urchin Strongylocentrotus droebachiensis in still water nor in shear, despite acidified individuals being significantly smaller in size (reduced growth rate). This maintenance of speed and stability in shear was accompanied by an overall change in size-corrected shape, implying changes in swimming biomechanics. Our observations highlight strong evolutionary pressure to maintain swimming in a varying environment and the plasticity in larval responses to environmental change.

Larval development to the first eighth zoeal stages in the deep-sea caridean shrimp Plesionika grandis Doflein, 1902 (Crustacea, Decapoda, Pandalidae).

PubMed

Jiang, Guo-Chen; Chan, Tin-Yam; Shih, Tung-Wei

2017-01-01

The larvae of the deep-sea pandalid shrimp Plesionika grandis Doflein, 1902 were successfully reared in the laboratory for the first time. The larvae reached the eighth zoeal stage in 36 days, both of which are longest records for the genus. Early larval stages of P. grandis bear the general characters of pandalid shrimps and differ from the other two species of Plesionika with larval morphology known in the number of spines on the anteroventral margin of carapace, number of tubercles on antennule, endopod segmentation in antenna, and third maxilliped setation. Although members in Plesionika are often separated into species groups, members of the same species group do not necessarily have similar early larval morphology. Since the zoea VIII of P. grandis still lacks pleopods and fifth pereiopod, this shrimp likely has at least 12 zoeal stages and a larval development of 120 days.

Ocean acidification boosts larval fish development but reduces the window of opportunity for successful settlement.

PubMed

Rossi, Tullio; Nagelkerken, Ivan; Simpson, Stephen D; Pistevos, Jennifer C A; Watson, Sue-Ann; Merillet, Laurene; Fraser, Peter; Munday, Philip L; Connell, Sean D

2015-12-22

Locating appropriate settlement habitat is a crucial step in the life cycle of most benthic marine animals. In marine fish, this step involves the use of multiple senses, including audition, olfaction and vision. To date, most investigations of larval fish audition focus on the hearing thresholds to various frequencies of sounds without testing an ecological response to such sounds. Identifying responses to biologically relevant sounds at the development stage in which orientation is most relevant is fundamental. We tested for the existence of ontogenetic windows of reception to sounds that could act as orientation cues with a focus on vulnerability to alteration by human impacts. Here we show that larvae of a catadromous fish species (barramundi, Lates calcarifer) were attracted towards sounds from settlement habitat during a surprisingly short ontogenetic window of approximately 3 days. Yet, this auditory preference was reversed in larvae reared under end-of-century levels of elevated CO2, such that larvae are repelled from cues of settlement habitat. These future conditions also reduced the swimming speeds and heightened the anxiety levels of barramundi. Unexpectedly, an acceleration of development and onset of metamorphosis caused by elevated CO2 were not accompanied by the earlier onset of attraction towards habitat sounds. This mismatch between ontogenetic development and the timing of orientation behaviour may reduce the ability of larvae to locate habitat or lead to settlement in unsuitable habitats. The misinterpretation of key orientation cues can have implications for population replenishment, which are only exacerbated when ontogenetic development decouples from the specific behaviours required for location of settlement habitats. © 2015 The Author(s).

Diversity of olfactomedin proteins in the sea urchin.

PubMed

Hillier, Brian J; Moy, Gary W; Vacquier, Victor D

2007-06-01

Olfactomedin (OLF) domain proteins maintain extracellular protein-protein interactions in diverse phyla. Only one OLF family member, amassin-1, has been described from the sea urchin Strongylocentrotus purpuratus, a basal invertebrate deuterostome. Amassin-1 mediates intercellular adhesion of coelomocytes (immunocytes). Here we describe the protein structural features of four additional OLF proteins, the total for the genome being five. Phylogenetically, four of these proteins (the amassins) form a subgroup among previously identified OLF proteins. The fifth OLF protein is within the colmedin subfamily and contains a type II transmembrane domain, collagen repeats, and an OLF domain. Sea urchin OLF proteins represent an intermediate diversification between protostomes and vertebrates. Transcripts of all five OLF family members are in coelomocytes and adult radial nerve tissue. Transcripts for some OLF proteins increase during late larval stages. Transcript levels for amassin-1 increase 1,000,000-fold, coinciding with formation of the adult urchin rudiment within the larval body.

Effect of ivermectin treatment on eosinophilic pneumonia and other extravascular lesions of late Strongylus vulgaris larval migration in foals.

PubMed

Turk, M A; Klei, T R

1984-01-01

Eighteen parasite-free pony foals were infected orally with 500 third stage larvae of Strongylus vulgaris. At 56 days after infection, six ponies were treated with intramuscular ivermectin (22, 23-dihydroavermectin B1); six were treated with oral ivermectin; and six were not treated. Necropsy was done 91 days after infection to study the pathologic effects of migrating S. vulgaris larvae and to determine the efficacy of ivermectin in attenuation of S. vulgaris-induced lesions. Larval migration induced eosinophilic inflammation of the liver, spleen, mesenteric, colic and cecal lymph nodes, and small and large intestine. Previously unreported parasitic lesions included eosinophilic pneumonia with eosinophilic granulomas and pulmonary lymphoid nodules. S. vulgaris larvae were observed in eosinophilic granulomas in the lung, epicardium, liver, and intestinal serosa. Injectable and oral ivermectin formulations were equally effective in reduction of these lesions.

A field guide to amphibian larvae and eggs of Minnesota, Wisconsin, and Iowa

USGS Publications Warehouse

Parmelee, J.R.; Knutson, M.G.; Lyon, J.E.

2002-01-01

Apparent worldwide declines in amphibian populations (Pechmann and Wake 1997) have stimulated interest in amphibians as bioindicators of the health of ecosystems. Because we have little information on the population status of many species, there is interest by public and private land management agencies in monitoring amphibian populations. Amphibian egg and larval surveys are established methods of surveying pond-breeding amphibians. Adults may be widely dispersed across the landscape, but eggs and larvae are confined to the breeding site during a specific season of the year. Also, observations of late-stage larvae or metamorphs are evidence of successful reproduction, which is an important indicator of the viability of the population. The goal of this guide is to help students, natural resources personnel, and biologists identify eggs and larval stages of amphibians in the field without the aid of a microscope.

Incorporation of habitat information in the development of indices of larval bluefin tuna (Thunnus thynnus) in the Western Mediterranean Sea (2001-2005 and 2012-2013)

NASA Astrophysics Data System (ADS)

Ingram, G. Walter; Alvarez-Berastegui, Diego; Reglero, Patricia; Balbín, Rosa; García, Alberto; Alemany, Francisco

2017-06-01

Fishery independent indices of bluefin tuna larvae in the Western Mediterranean Sea are presented utilizing ichthyoplankton survey data collected from 2001 through 2005 and 2012 through 2013. Indices were developed using larval catch rates collected using two different types of bongo sampling, by first standardizing catch rates by gear/fishing-style and then employing a delta-lognormal modeling approach. The delta-lognormal models were developed three ways: 1) a basic larval index including the following covariates: time of day, a systematic geographic area variable, month and year; 2) a standard environmental larval index including the following covariates: mean water temperature over the mixed layer depth, mean salinity over the mixed layer depth, geostrophic velocity, time of day, a systematic geographic area variable, month and year; and 3) a habitat-adjusted larval index including the following covariates: a potential habitat variable, time of day, a systematic geographic area variable, month and year. Results indicated that all three model-types had similar precision in index values. However, the habitat-adjusted larval index demonstrated a high correlation with estimates of spawning stock biomass from the previous stock assessment model, and, therefore, is recommended as a tuning index in future stock assessment models.

Morphology of First Zoeal Stage of Four Genera of Alvinocaridid Shrimps from Hydrothermal Vents and Cold Seeps: Implications for Ecology, Larval Biology and Phylogeny

PubMed Central

Hernández-Ávila, Iván; Cambon-Bonavita, Marie-Anne; Pradillon, Florence

2015-01-01

Alvinocaridid shrimps are endemic species inhabiting hydrothermal vents and/or cold seeps. Although indirect evidences (genetic and lipid markers) suggest that their larval stages disperse widely and support large scale connectivity, larval life and mechanisms underlying dispersal are unknown in alvinocaridids. Here we provide for the first time detailed descriptions of the first larval stage (zoea I) of four alvinocaridid species: Rimicaris exoculata and Mirocaris fortunata from the Mid-Atlantic Ridge, Alvinocaris muricola from the Congo Basin and Nautilocaris saintlaurentae from the Western Pacific. The larvae were obtained from onboard hatching of brooding females (either at atmospheric pressure or at habitat pressure in hyperbaric chambers) and from the water column near adult habitats, sampled with plankton pumps or sediment traps. Major characteristics of the alvinocaridid larvae include undeveloped mandible and almost complete absence of setation in the inner margin of the mouth parts and maxillipeds. Although the larvae are very similar between the four species studied, some morphological features could be used for species identification. In addition, undeveloped mouthparts and the large amount of lipid reserves strongly support the occurrence of primary lecithotrophy in the early stage of alvinocaridids. Although lecithotrophy in decapod crustaceans is usually associated with abbreviated larval development, as a mechanism of larval retention, morphological and physiological evidences suggest the occurrence of an extended and lecithotrophic larval stage in the Alvinocarididae. These traits permit the colonization of widely dispersed and fragmented environments of hydrothermal vents and cold seeps. Distribution of larval traits along the phylogenetic reconstruction of the Alvinocarididae and related families suggest that lecithotrophy/planktotrophy and extended/abbreviated development have evolved independently along related families in all potential combinations. However, the Alvinocarididae is the only taxa with a combination of lecithotrophy and extended larval development. PMID:26710075

Functional morphology of mouthparts and digestive system during larval development of the cleaner shrimp Lysmata amboinensis (de Man, 1888).

PubMed

Tziouveli, Vasiliki; Bastos Gomes, Giana; Bastos-Gomez, Giana; Bellwood, Orpha

2011-09-01

Mouthpart and alimentary canal development was examined in Lysmata amboinensis larvae using scanning electron microscopy and histology. The gross morphological features of external mouthparts and internal digestive tract structures of larvae at different developmental stages indicate that ingestive and digestive capabilities are well developed from early on. With increasing age of the larvae the mouthpart appendages increased in size, the hepatopancreas in tubular density and the midgut in length. The density of setae and robustness of teeth and spines of individual structures increased. The most pronounced changes from early to late stage larvae involved formation of pores on the paragnaths and labrum, transformation of the mandibular spine-like teeth to molar cusps, development of the filter press in the proventriculus and of infoldings in the previously straight hindgut. The results suggest that early stage L. amboinensis larvae may benefit from soft, perhaps gelatinous prey, whereas later stages are better equipped to handle larger, muscular or more fibrous foods. 2011 Wiley-Liss, Inc.

Development of the larval amphibian growth and development assay: Effects of benzophenone-2 exposure in Xenopus laevis from embryo to juvenile

EPA Science Inventory

The Larval Amphibian Growth and Development Assay (LAGDA) is a globally harmonized chemical testing guideline developed by the U.S. Environmental Protection Agency in collaboration with Japan’s Ministry of Environment to support risk assessment. The assay is employed as a ...

Simulated Seasonal Photoperiods and Fluctuating Temperatures Have Limited Effects on Blood Feeding and Life History in Aedes triseriatus (Diptera: Culicidae)

PubMed Central

Westby, K. M.

2015-01-01

Biotic and abiotic factors change seasonally and impact life history in temperate-zone ectotherms. Temperature and photoperiod are factors that change in predictable ways. Most studies testing for effects of temperature on vectors use constant temperatures and ignore potential correlated effects of photoperiod. In two experiments, we tested for effects of larval rearing environments creating ecologically relevant temperatures and photoperiods simulating early and late season conditions (June and August), or constant temperatures (cool and warm) with the June or August photoperiods, respectively. We determined effects on survivorship, development, size, and a composite performance index in a temperate-zone population of Aedes triseriatus (Say). We followed cohorts of resulting females, all held under the same environmental conditions, to assess carry-over effects of rearing conditions for larvae on longevity, blood feeding, and egg production. Larval survivorship was affected by treatment in one experiment. Development time was greater in the June and cool treatments, but the constant and fluctuating temperatures did not differ. Significantly larger mosquitoes were produced in fluctuating versus constant temperature treatments. There were no significant treatment effects on the composite performance index. Adult female longevity was lower after rearing at constant versus fluctuating temperature, but there was no difference between June and August, nor did size affect longevity. There was no effect of treatments on blood feeding and a limited effect on egg production. We conclude that seasonal temperatures and photoperiods during development have limited effects on this population of A. triseriatus and find little evidence of strong effects of fluctuating versus constant temperatures. PMID:26336255

Microbial composition affects the performance of an artificial Tephritid larval diet.

PubMed

Rempoulakis, P; Sela Saldinger, S; Nemny-Lavy, E; Pinto, R; Birke, A; Nestel, D

2017-09-20

The present study investigated the patterns of microorganisms in an artificial larval diet during Dacus ciliatus (Diptera; Tephritidae) larval development. Microbial population contents in the diet of total heterotrophic bacteria, yeast and molds, coliform and lactobacilli, and their dynamics during development, were monitored. Initially, the microbial composition in diet trays failing to produce viable pupae and in trays successfully producing pupae and adult flies was characterized. The failing diet trays contained large populations of lactobacilli that increased during larval development, and low populations of coliforms. In contrast, the successful diet showed an increasing population of coliforms and a low, or undetected, population of lactobacilli. To study the hypothesis that lactobacilli affect D. ciliatus larval development, we conducted controlled inoculation experiments in which Lactobacillus plantarum was added into fresh diet at the time of egg seeding. L. plantarum inoculated trays showed no production of D. ciliatus. Control trays without lactobacilli inoculation showed variable results. One tray successfully produced viable pupae and adults, and showed a slight and slow increase in the indigenous populations of lactobacilli. The second tray, however, failed to produce pupae and showed a fast increase of the indigenous lactobacilli to very high levels. Monitored pH trends in L. plantarum-inoculated diet showed a sharp pH decrease during the first 4 days of larval development from 5 to less than 4 units, while successful diet, producing viable D. ciliatus pupae and adults, showed a moderate pH drop during most of the larval development period. The paper discusses the possible ecological interactions between D. ciliatus larvae, the microbial content of the diet and the physical properties of the diet. The discussion also points out at the usefulness of this approach in understanding and managing mass production parameters of tephritid fruit flies industrial diets used for Sterile Insect Technique.

Effects of temperature and diet on black soldier fly, Hermetia illucens (L.) (Diptera: Stratiomyidae), development.

PubMed

Harnden, Laura M; Tomberlin, Jeffery K

2016-09-01

The black soldier fly, Hermetia illucens, is recognised for its use in a forensic context as a means for estimating the time of colonisation and potentially postmortem interval of decomposing remains. However, little data exist on this species outside of its use in waste management. This study offers a preliminary assessment of the development, and subsequent validation, of H. illucens. Larvae of H. illucens were reared at three temperatures (24.9°C, 27.6°C and 32.2°C) at 55% RH on beef loin muscle, pork loin muscle and a grain-based diet (control). Each of the temperatures and diets were found to significantly (P<0.05) affect all stages of immature growth except for pupation time. Overall, those reared on the pork diet required on average ≈23.1% and ≈139.7% more degree hours to complete larval development than those reared on the beef and grain-based diets, respectively. Larvae reared at 27.6°C and 32.2°C required on average ≈8.7% more degree hours to complete development and had a final larval weight ≈30% greater than larvae reared at 24.9°C. The validity of the laboratory larval length and weight data sets was assessed via estimating the age of field-reared larvae. Grain-diet data lacked accuracy when used to estimate larval age in comparison to estimates made with beef and pork-diet data, which were able to predict larval age for ≈55.6% and ≈88.9% of sampling points, respectively, when length and weight data were used in conjunction. Field-reared larval sizes exceeded the maximum observed under laboratory conditions in almost half of the samples, which reduced estimate accuracy. Future research should develop additional criteria for identifying development of each specific instar, which may aid in improving the accuracy and precision of larval age estimates for this species. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Development of the Drosophila entero-endocrine lineage and its specification by the Notch signaling pathway

PubMed Central

Takashima, Shigeo; Adams, Katrina L.; Ortiz, Paola A.; Ying, Chong T.; Moridzadeh, Rameen; Younossi-Hartenstein, Amelia; Hartenstein, Volker

2013-01-01

In this paper we have investigated the developmental-genetic steps that shape the entero-endocrine system of Drosophila melanogaster from the embryo to the adult. The process starts in the endoderm of the early embryo where precursors of endocrine cells and enterocytes of the larval midgut, as well as progenitors of the adult midgut, are specified by a Notch signaling-dependent mechanism. In a second step that occurs during the late larval period, enterocytes and endocrine cells of a transient pupal midgut are selected from within the clusters of adult midgut progenitors. As in the embryo, activation of the Notch pathway triggers enterocyte differentiation, and inhibits cells from further proliferation or choosing the endocrine fate. The third step of entero-endocrine cell development takes place at a mid-pupal stage. Before this time point, the epithelial layer destined to become the adult midgut is devoid of endocrine cells. However, precursors of the intestinal midgut stem cells (pISCs) are already present. After an initial phase of symmetric divisions which causes an increase in their own population size, pISCs start to spin off cells that become postmitotic and express the endocrine fate marker, Prospero. Activation of Notch in pISCs forces these cells into an enterocyte fate. Loss of Notch function causes an increase in the proliferatory activity of pISCs, as well as a higher ratio of Prospero-positive cells. PMID:21382366

Development and infectious disease in hosts with complex life cycles.

PubMed

Searle, Catherine L; Xie, Gisselle Yang; Blaustein, Andrew R

2013-01-01

Metamorphosis is often characterized by profound changes in morphology and physiology that can affect the dynamics of species interactions. For example, the interaction between a pathogen and its host may differ depending on the life stage of the host or pathogen. One pathogen that infects hosts with complex life cycles is the emerging fungal pathogen of amphibians, Batrachochytrium dendrobatidis (Bd). We sought to determine how conditions at the larval stage can affect variation in development and patterns of Bd infection across amphibian life stages. We used outdoor experimental mesocosms to simulate natural pond habitats and manipulated the presence of Bd, the larval density, and the number of host species in larvae of two co-occurring amphibian species (Rana cascadae and Pseudacris regilla). We found that infection differed between species throughout development; P. regilla consistently had higher infection severity compared to R. cascadae. Additionally, while up to 100% of larvae were infected, only 18.2% of R. cascadae and 81.5% of P. regilla were infected after metamorphosis. This indicates that amphibians have the ability to recover from Bd infection as they undergo metamorphosis. Higher larval densities in P. regilla led to a shorter larval period, and individuals with a shorter larval period had lower infection severity. This led to a trend where P. regilla larvae reared at high densities tended to have lower infection prevalence after metamorphosis. We also found that exposure to Bd increased larval mortality and prolonged the larval period in P. regilla, indicating that P. regilla are susceptible to the negative effects of Bd as larvae. This study demonstrates that host density, species composition, and pathogen exposure may all interact to influence development and infection in hosts with complex life cycles.

Exploring Larval Development and Applications in Marine Fish Aquaculture Using Pink Snapper Embryos

ERIC Educational Resources Information Center

Tamaru, Clyde; Haverkort-Yeh, Roxanne D.; Gorospe, Kelvin D.; Rivera, Malia Ana J.

2014-01-01

This biology investigation on "Pristipomoides filamentosus" larval development, survival, and aquaculture research was developed with three educational objectives: to provide high school students with (1) a scientific background on the biology and science of fisheries as well as overfishing, its consequences, and possible mitigations;…

Selection in the host structures the microbiota associated with developing cod larvae (Gadus morhua).

PubMed

Bakke, Ingrid; Coward, Eivind; Andersen, Tom; Vadstein, Olav

2015-10-01

Marine fish larvae are immature upon hatching, and share their environment with high numbers of bacteria. The microbial communities associated with developing fish larvae might be structured by other factors than those important in developing terrestrial animals. Here, we analysed the beta (β)-diversity of the microbiota associated with developing cod larvae and compared it with the bacterial communities in water and live feed by applying pyrosequencing of bar coded v4 16S rDNA amplicons. A total of 15 phyla were observed in the cod larval microbiota. Proteobacteria was the most abundant, followed by Firmicutes, Bacteroidetes and Actinobacteria. The composition and diversity of the cod larval microbiota changed considerably with age. The temporal and spatial patterns of β-diversity could not be explained by stochastic processes, and did not coincide with changes in the rearing conditions. Furthermore, the larval microbiota was highly distinct from the water and the live feed microbiota, particularly at early developmental stages. However, the similarity between larval and water microbiota increased with age. This study suggests that strong selection in the host structures the cod larval microbiota. The changes in community structure observed with increasing age can be explained by altered selection pressure due to development of the intestinal system. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Decline in offspring viability as a manifestation of aging in Drosophila melianogaster.

PubMed

Kern, S; Ackermann, M; Stearns, S C; Kawecki, T J

2001-09-01

The evolutionary explanation of senescence proposes that selection against alleles with deleterious effects manifested only late in life is weak because most individuals die earlier for extrinsic reasons. This argument also applies to alleles whose deleterious effects are nongenetically transmitted from mother to progeny, that is, that affect the performance of progeny produced at late ages rather than of the aging individuals themselves. We studied the effect of maternal age on offspring viability (egg hatching success and larva-to-adult survival) in two sets of Drosophila melanogaster lines (HAM/LAM and YOUNG/OLD), originating from two long-term selection experiments. In each set, some lines (HAM and YOUNG, respectively) have been selected for early reproduction, whereas later reproduction was favored in their counterparts (LAM and OLD). In the HAM and LAM lines, both egg hatching success and larval viability declined with mother's age and did so with accelerating rates. The hatching success declined significantly faster with maternal age in HAM than in LAM lines, according to one of two statistical approaches used. Egg hatching success also declined with maternal age in YOUNG and OLD lines, with no difference between the selection regimes. However, the relationship between mother's age and offspring larva-to-adult viability differed significantly between these two selection regimes: a decline of larval viability with maternal age occurred in YOUNG lines but not in OLD lines. This suggests that the rate with which offspring viability declines with mother's age responded to selection for early versus late reproduction. We suggest broadening the evolutionary concept of senescence to include intrinsically caused declines in offspring quality with maternal age.

How does competition among wild type mosquitoes influence the performance of Aedes aegypti and dissemination of Wolbachia pipientis?

PubMed Central

de Oliveira, Suellen; Villela, Daniel Antunes Maciel; Dias, Fernando Braga Stehling; Moreira, Luciano Andrade

2017-01-01

Background Wolbachia has been deployed in several countries to reduce transmission of dengue, Zika and chikungunya viruses. During releases, Wolbachia-infected females are likely to lay their eggs in local available breeding sites, which might already be colonized by local Aedes sp. mosquitoes. Therefore, there is an urgent need to estimate the deleterious effects of intra and interspecific larval competition on mosquito life history traits, especially on the duration of larval development time, larval mortality and adult size. Methodology/principal findings Three different mosquito populations were used: Ae. aegypti infected with Wolbachia (wMelBr strain), wild Ae. aegypti and wild Ae. albopictus. A total of 21 treatments explored intra and interspecific larval competition with varying larval densities, species proportions and food levels. Each treatment had eight replicates with two distinct food levels: 0.25 or 0.50 g of Chitosan and fallen avocado leaves. Overall, overcrowding reduced fitness correlates of the three populations. Ae. albopictus larvae presented lower larval mortality, shorter development time to adult and smaller wing sizes than Ae. aegypti. The presence of Wolbachia had a slight positive effect on larval biology, since infected individuals had higher survivorship than uninfected Ae. aegypti larvae. Conclusions/significance In all treatments, Ae. albopictus outperformed both wild Ae. aegypti and the Wolbachia-infected group in larval competition, irrespective of larval density and the amount of food resources. The major force that can slow down Wolbachia invasion is the population density of wild mosquitoes. Given that Ae. aegypti currently dominates in Rio, in comparison with Ae. albopictus frequency, additional attention must be given to the population density of Ae. aegypti during releases to increase the likelihood of Wolbachia invasion. PMID:28991902

Large-Scale Ichthyoplankton and Water Mass Distribution along the South Brazil Shelf

PubMed Central

de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

2014-01-01

Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27′ and 34°51′S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients. PMID:24614798

Ocean acidification alters temperature and salinity preferences in larval fish.

PubMed

Pistevos, Jennifer C A; Nagelkerken, Ivan; Rossi, Tullio; Connell, Sean D

2017-02-01

Ocean acidification alters the way in which animals perceive and respond to their world by affecting a variety of senses such as audition, olfaction, vision and pH sensing. Marine species rely on other senses as well, but we know little of how these might be affected by ocean acidification. We tested whether ocean acidification can alter the preference for physicochemical cues used for dispersal between ocean and estuarine environments. We experimentally assessed the behavioural response of a larval fish (Lates calcarifer) to elevated temperature and reduced salinity, including estuarine water of multiple cues for detecting settlement habitat. Larval fish raised under elevated CO 2 concentrations were attracted by warmer water, but temperature had no effect on fish raised in contemporary CO 2 concentrations. In contrast, contemporary larvae were deterred by lower salinity water, where CO 2 -treated fish showed no such response. Natural estuarine water-of higher temperature, lower salinity, and containing estuarine olfactory cues-was only preferred by fish treated under forecasted high CO 2 conditions. We show for the first time that attraction by larval fish towards physicochemical cues can be altered by ocean acidification. Such alterations to perception and evaluation of environmental cues during the critical process of dispersal can potentially have implications for ensuing recruitment and population replenishment. Our study not only shows that freshwater species that spend part of their life cycle in the ocean might also be affected by ocean acidification, but that behavioural responses towards key physicochemical cues can also be negated through elevated CO 2 from human emissions.

Large-scale ichthyoplankton and water mass distribution along the South Brazil Shelf.

PubMed

de Macedo-Soares, Luis Carlos Pinto; Garcia, Carlos Alberto Eiras; Freire, Andrea Santarosa; Muelbert, José Henrique

2014-01-01

Ichthyoplankton is an essential component of pelagic ecosystems, and environmental factors play an important role in determining its distribution. We have investigated simultaneous latitudinal and cross-shelf gradients in ichthyoplankton abundance to test the hypothesis that the large-scale distribution of fish larvae in the South Brazil Shelf is associated with water mass composition. Vertical plankton tows were collected between 21°27' and 34°51'S at 107 stations, in austral late spring and early summer seasons. Samples were taken with a conical-cylindrical plankton net from the depth of chlorophyll maxima to the surface in deep stations, or from 10 m from the bottom to the surface in shallow waters. Salinity and temperature were obtained with a CTD/rosette system, which provided seawater for chlorophyll-a and nutrient concentrations. The influence of water mass on larval fish species was studied using Indicator Species Analysis, whereas environmental effects on the distribution of larval fish species were analyzed by Distance-based Redundancy Analysis. Larval fish species were associated with specific water masses: in the north, Sardinella brasiliensis was found in Shelf Water; whereas in the south, Engraulis anchoita inhabited the Plata Plume Water. At the slope, Tropical Water was characterized by the bristlemouth Cyclothone acclinidens. The concurrent analysis showed the importance of both cross-shelf and latitudinal gradients on the large-scale distribution of larval fish species. Our findings reveal that ichthyoplankton composition and large-scale spatial distribution are determined by water mass composition in both latitudinal and cross-shelf gradients.

Life cycle of lithobiidae - with a discussion of the r-and K-selection theory.

PubMed

Albert, Anke M

1983-02-01

The life cycle of two lithobiid species (Chilopoda: Lithobiidae) Lithobius mutabilis L. Koch and L. curtipes C.L. Koch in an old beech stand in the Solling is described. In addition to a main egg-laying period lithobiids are able to lay eggs continuously throughout the year. The reproductive potential is small, as only one egg is laid over several days. Most juveniles hatch in the spring and over-winter as L3 or L4 larvae. Epimorph development to attainment of sexual maturity takes nearly 2 years. Adult L. mutablilis live a further 2 years or more, adult L. curtipes about 1 year or more. Total life span is about 5-6 years for L. mutabilis and 4-5 years for L. curtipes. Egg development times and instar durations can be very different for different animals. Mortality is relatively high for eggs and small juveniles and low for post larval instars except the very old animals. A method is presented for construction of a survivorship curve from monthly abundance figures. Due to their slow development, late attainment of reproductive period, long reproductive phase, low reproductive potential, long life span, low mortality of post larval instars except very old animals, lithobiids can be regarded as K-strategists or, better, equilibrium species, among the arthropods. It is argued that the theory of r- and K-selection in its general use is not sufficient for a description of the ecological strategies of animals such as Lithobiomorpha. For lithobiids, variability in development time is a very important means of keeping population size at a constant level. The life cycle of the two lithobiid species is compared with ahat of Geophilomorpha and one henicopid species also occurring in the Solling.

Seasonal variation in the occurrence of planktic bivalve larvae in the Schleswig-Holstein Wadden Sea

NASA Astrophysics Data System (ADS)

Pulfrich, Andrea

1997-03-01

In the late 1980s, recruitment failures of the mussel Mytilus edulis led to economic problems in the mussel fishing and cultivation industries of northwestern Europe. As part of a collaborative study to gain a better understanding of the mechanisms affecting recruitment processes of mussels, plankton samples were collected regularly over a four-year period (1990-1993) from three stations in the Schleswig-Holstein Wadden Sea. The bivalve component of the plankton was dominated by the Solenidae, which was almost exclusively represented by Ensis americanus (= directus). M. edulis was the second most abundant species. Abundances of mussel larvae peaked 2 to 4 weeks after spawning maxima in the adult populations. Although variations in timing and amplitude of the total larval densities occurred, annual abundances of M. edulis larvae remained stable during the study period, and regional abundance differences were insignificant. A close relationship was found between peaks in larval abundance and phytoplankton blooms. Differences in larval concentrations in the ebb and the flow currents were insignificant. Planktic mussel larvae measured between 200 μm and 300 μm, and successive cohorts were recognizable in the majority of samples. Most larvae were found to originate from local stocks, although imports from outside the area do occur.

Morphology of the advanced-stage larva of Eustrongylides wenrichi Canavan 1929, occurring encapsulated in the tissues of Amphiuma in Louisiana.

PubMed

Panesar, T S; Beaver, P C

1979-02-01

Larval nematodes identified as Eustrongylides wenrichi Canavan 1929, from cysts in the tissues of Amphiuma means tridactylum Cuvier in Louisana were redescribed. The extent of differentiation of the sex organs was found to be greater than that of 3rd-stage Dioctophyma renale, or of the infective stage of Trichinella spiralis, and comparable with the late 4th-stage larva of secernentean (phasmid) nematodes.

Detecting host-parasitoid interactions in an invasive Lepidopteran using nested tagging DNA metabarcoding.

PubMed

Kitson, James J N; Hahn, Christoph; Sands, Richard J; Straw, Nigel A; Evans, Darren M; Lunt, David H

2018-02-27

Determining the host-parasitoid interactions and parasitism rates for invasive species entering novel environments is an important first step in assessing potential routes for biocontrol and integrated pest management. Conventional insect rearing techniques followed by taxonomic identification are widely used to obtain such data, but this can be time-consuming and prone to biases. Here, we present a next-generation sequencing approach for use in ecological studies which allows for individual-level metadata tracking of large numbers of invertebrate samples through the use of hierarchically organised molecular identification tags. We demonstrate its utility using a sample data set examining both species identity and levels of parasitism in late larval stages of the oak processionary moth (Thaumetopoea processionea-Linn. 1758), an invasive species recently established in the United Kingdom. Overall, we find that there are two main species exploiting the late larval stages of oak processionary moth in the United Kingdom with the main parasitoid (Carcelia iliaca-Ratzeburg, 1840) parasitising 45.7% of caterpillars, while a rare secondary parasitoid (Compsilura concinnata-Meigen, 1824) was also detected in 0.4% of caterpillars. Using this approach on all life stages of the oak processionary moth may demonstrate additional parasitoid diversity. We discuss the wider potential of nested tagging DNA metabarcoding for constructing large, highly resolved species interaction networks. © 2018 John Wiley & Sons Ltd.

Location Isn’t Everything: Timing of Spawning Aggregations Optimizes Larval Replenishment

PubMed Central

Donahue, Megan J.; Karnauskas, Mandy; Toews, Carl; Paris, Claire B.

2015-01-01

Many species of reef fishes form large spawning aggregations that are highly predictable in space and time. Prior research has suggested that aggregating fish derive fitness benefits not just from mating at high density but, also, from oceanographic features of the spatial locations where aggregations occur. Using a probabilistic biophysical model of larval dispersal coupled to a fine resolution hydrodynamic model of the Florida Straits, we develop a stochastic landscape of larval fitness. Tracking virtual larvae from release to settlement and incorporating changes in larval behavior through ontogeny, we found that larval success was sensitive to the timing of spawning. Indeed, propagules released during the observed spawning period had higher larval success rates than those released outside the observed spawning period. In contrast, larval success rates were relatively insensitive to the spatial position of the release site. In addition, minimum (rather than mean) larval survival was maximized during the observed spawning period, indicating a reproductive strategy that minimizes the probability of recruitment failure. Given this landscape of larval fitness, we take an inverse optimization approach to define a biological objective function that reflects a tradeoff between the mean and variance of larval success in a temporally variable environment. Using this objective function, we suggest that the length of the spawning period can provide insight into the tradeoff between reproductive risk and reward. PMID:26103162

Exploration of the "larval pool": development and ground-truthing of a larval transport model off leeward Hawai'i.

PubMed

Wren, Johanna L K; Kobayashi, Donald R

2016-01-01

Most adult reef fish show site fidelity thus dispersal is limited to the mobile larval stage of the fish, and effective management of such species requires an understanding of the patterns of larval dispersal. In this study, we assess larval reef fish distributions in the waters west of the Big Island of Hawai'i using both in situ and model data. Catches from Cobb midwater trawls off west Hawai'i show that reef fish larvae are most numerous in offshore waters deeper than 3,000 m and consist largely of pre-settlement Pomacanthids, Acanthurids and Chaetodontids. Utilizing a Lagrangian larval dispersal model, we were able to replicate the observed shore fish distributions from the trawl data and we identified the 100 m depth strata as the most likely depth of occupancy. Additionally, our model showed that for larval shore fish with a pelagic larval duration longer than 40 days there was no significant change in settlement success in our model. By creating a general additive model (GAM) incorporating lunar phase and angle we were able to explain 67.5% of the variance between modeled and in situ Acanthurid abundances. We took steps towards creating a predictive larval distribution model that will greatly aid in understanding the spatiotemporal nature of the larval pool in west Hawai'i, and the dispersal of larvae throughout the Hawaiian archipelago.

[Specific features of digestive function development in larvae of some salmonid fish].

PubMed

Ershova, T S; Volkova, I V; Zaĭtseva, V F

2004-01-01

We studied the activities of digestive enzymes responsible for the digestion of food carbohydrate and protein components in plant-eating fish at various stages of larval development. The activities of all digestive enzymes tend to rise during larval development. Species specific features of the alimentary canal functioning have been described.

Effects of temperature on embryonic and early larval growth and development in the rough-skinned newt (Taricha granulosa).

PubMed

Smith, Geoffrey D; Hopkins, Gareth R; Mohammadi, Shabnam; M Skinner, Heather; Hansen, Tyler; Brodie, Edmund D; French, Susannah S

2015-07-01

We investigated the effects of temperature on the growth and development of embryonic and early larval stages of a western North American amphibian, the rough-skinned newt (Taricha granulosa). We assigned newt eggs to different temperatures (7, 14, or 21°C); after hatching, we re-assigned the newt larvae into the three different temperatures. Over the course of three to four weeks, we measured total length and developmental stage of the larvae. Our results indicated a strong positive relationship over time between temperature and both length and developmental stage. Importantly, individuals assigned to cooler embryonic temperatures did not achieve the larval sizes of individuals from the warmer embryonic treatments, regardless of larval temperature. Our investigation of growth and development at different temperatures demonstrates carry-over effects and provides a more comprehensive understanding of how organisms respond to temperature changes during early development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Modelling developmental changes in the carbon and nitrogen budgets of larval brachyuran crabs

NASA Astrophysics Data System (ADS)

Anger, K.

1990-03-01

The uptake and partitioning of nutritional carbon (C) and nitrogen (N) were studied during the complete larval development of a brachyuran crab, Hyas araneus, reared under constant conditions in the laboratory. Biochemical and physiological data were published in a foregoing paper, and complete budgets of C and N were now constructed from these data. Regression equations describing rates of feeding ( F), growth ( G), respiration ( R), and ammonia excretion ( U) as functions of time during individual larval moult cycles were inserted in a simulation model, in order to analyse time-dependent (i.e. developmental) patterns of variation in these parameters as well as in bioenergetic efficiencies. Absolute daily feeding rates ( F; per individual) as well as carbon and nitrogen-specific rates ( F/C, F/N) are in general maximum in early, and minimum in late stages of individual larval moult cycles (postmoult and premoult, respectively). Early crab zoeae may ingest equivalents of up to ca 40% body C and 30% body N per day, respectively, whereas megalopa larvae usually eat less than 10%. Also growth rates ( G; G/C, G/N) reveal decreasing tendencies both during individual moult cycles and, on the average, in subsequent instars. Conversion of C and N data to lipid and protein, respectively, suggests that in all larval instars there is initially an increase in the lipid: protein ratio. Protein, however, remains clearly the predominant biochemical constituent in larval biomass. The absolute and specific values of respiration ( R; R/C) and excretion ( U; U/N) vary only little during the course of individual moult cycles. Thus, their significance in relation to G increases within the C and N budgets, and net growth efficiency ( K 2) decreases concurrently. Also gross growth and assimilation efficiency ( K 2; A/F) are, in general, maximum in early stages of the moult cycle (postmoult). Biochemical data suggest that lipid utilization efficiency is particularly high in early moult cycle stages, whereas protein utilization efficiency is higher in later stages. Only the zoea II appears to accumulate lipid from food constantly with a higher conversion efficiency than protein. The cumulative C and N budgets show in subsequent larval instars conspicuously increasing figures in all of their parameters. F and G increase to a particularly high extent from the first to the second zoeal instar, whereas R, U, exuvia production ( G E), and total assimilation ( A) reveal a greater increase from the zoea II to the megalopa. Respiratory, excretory, and exuvial losses increase in subsequent larval instars at higher rates than tissue growth and, hence, K 2 decreases in the same order. In the C budget, K 2 values of 0.63 (zoea I). 0.56 (zoea II), and 0.29 (megalopa) were calculated (or: 0.56, 0.46, and 0.16 after subtraction of exuviae). In the N budget, corresponding values of 0.76, 0.66, and 0.45 (or: 0.72, 0.62, 0.38 without exuviae) were obtained. Also K 1 decreases slightly in subsequent instars, whereas A/F reveals rather an increasing tendency, at least from the zoeal instars to the megalopa. Changes in the uptake and partitioning of matter in crab larvae are discussed in relation to developmental events and changes in life style before metamorphosis.

Expression patterns of wnt8 orthologs in two sand dollar species with different developmental modes.

PubMed

Nakata, Hidewo; Minokawa, Takuya

2009-03-01

Two wnt8 orthologs, Smwnt8 and Pjwnt8, were isolated from an indirect developing sand dollar, Scaphechinus mirabilis, and a direct developing sand dollar, Peronella japonica, respectively. The expression patterns of two genes during early development were examined by whole mount in situ hybridization. The expression of Smwnt8 was initiated in the micromeres at the late 16-cell stage and expanded at the 64-cell stage to the whole vegetal hemisphere, including the presumptive endomesodermal regions. The timing of the initiation of Pjwnt8 transcription in the presumptive endomesoderm region was delayed by 2-3 cell cycles compared to that of Smwnt8. The delay, or molecular heterochrony, of Pjwnt8 transcription strongly suggests the existence of a substantial evolutionary change in the early endomesodermal specification of P. japonica. In addition to the endomesodermal expression during early embryogenesis, bilateral expressions were observed commonly in the ectoderm of two sand dollar species during larval stages.

Reverse osmosis and ultrafiltration for recovery and reuse of larval rearing water in Anopheles arabiensis mass production: Effect of water quality on larval development and fitness of emerging adults.

PubMed

Mamai, Wadaka; Hood-Nowotny, Rebecca; Maiga, Hamidou; Ali, Adel Barakat; Bimbile-Somda, Nanwintoun S; Soma, Diloma Dieudonné; Yamada, Hanano; Lees, Rosemary Susan; Gilles, Jeremie R L

2017-06-01

Countries around the world are showing increased interest in applying the sterile insect technique against mosquito disease vectors. Many countries in which mosquitoes are endemic, and so where vector control using the sterile insect technique may be considered, are located in arid zones where water provision can be costly or unreliable. Water reuse provides an alternate form of water supply. In order to reduce the cost of mass rearing of Anopheles arabiensis mosquitoes, the possibility of recycling and reusing larval rearing water was explored. The used rearing water ('dirty water') was collected after the tilting of rearing trays for collection of larvae/pupae, and larvae/pupae separation events and underwent treatment processes consisting of ultrafiltration and reverse osmosis. First-instar An. arabiensis larvae were randomly assigned to different water-type treatments, 500 larvae per laboratory rearing tray: 'clean' dechlorinated water, routinely used in rearing; dirty water; and 'recycled' dirty water treated using reverse osmosis and ultrafiltration. Several parameters of insect quality were then compared: larval development, pupation rate, adult emergence, body size and longevity. Water quality of the samples was analyzed in terms of ammonia, nitrite, nitrate, sulphate, dissolved oxygen, chloride, and phosphate concentrations after the larvae had all pupated or died. Surface water temperatures were also recorded continuously during larval development. Pupation rates and adult emergence were similar in all water treatments. Adult body sizes of larvae reared in recycled water were similar to those reared in clean water, but larger than those reared in the dirty larval water treatment, whereas the adult longevity of larvae reared in recycled water was significantly increased relative to both 'clean' and 'dirty' water. Dirty larval water contained significantly higher concentrations of ammonium, sulfate, phosphate and chloride and lower levels of dissolved oxygen than clean water. These parameters significantly varied during the period of larval development. After dirty water was recycled by ultrafiltration and reverse osmosis, all the parameters measured were the same as those in clean water. This study demonstrated the potential for using recycled larval rearing water to supplement clean dechlorinated water supplies. Recycling used water improved its quality and of the reared mosquitoes. As water demands and environmental pressures grow, recycling of larval rearing water will improve the sustainability and affordability of mosquito mass-rearing. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of the larval amphibian growth and development assay: Effects of chronic 4-tert-octylphenol or 17ß-trenbolone exposure in Xenopus laevis from embryo to juvenile

EPA Science Inventory

The Larval Amphibian Growth and Development Assay (LAGDA) is a Tier II test guideline being developed by the US Environmental Protection Agency under the Endocrine Disruptor Screening Program. The LAGDA was designed to evaluate effects of chronic chemical exposure on growth, thy...

Identification of Gender-specific Transcripts by Microarray in Gonad Tissue of Larval and Juvenile Xenopus tropicalis

EPA Science Inventory

Amphibian model species Xenopus tropicalis is currently being utilized by EPA in the development of a standardized in vivo reproductive toxicity assay. Perturbations to the hypothalamic-pituitary-gonadal axis from exposure to endocrine disrupting compounds during larval develop...

Dietary supplementation with vitamin k affects transcriptome and proteome of Senegalese sole, improving larval performance and quality.

PubMed

Richard, Nadège; Fernández, Ignacio; Wulff, Tune; Hamre, Kristin; Cancela, Leonor; Conceição, Luis E C; Gavaia, Paulo J

2014-10-01

Nutritional factors strongly influence fish larval development and skeletogenesis, and may induce skeletal deformities. Vitamin K (VK) has been largely disregarded in aquaculture nutrition, despite its important roles in bone metabolism, in γ-carboxylation of Gla proteins, and in regulating gene expression through the pregnane X receptor (Pxr). Since the mechanisms mediating VK effects over skeletal development are poorly known, we investigated the effects of VK-supplementation on skeletal development in Senegalese sole larvae, aiming to identify molecular pathways involved. Larvae were fed live preys enriched with graded levels of phylloquinone (PK) (0, 50, and 250 mg kg(-1)) and survival rate, growth, VK contents, calcium content and incidence of skeletal deformities were determined, revealing an improvement of larval performance and decreasing the incidence of deformities in VK-supplemented groups. Comparative proteome analysis revealed a number of differentially expressed proteins between Control and Diet 250 associated with key biological processes including skin, muscle, and bone development. Expression analysis showed that genes encoding proteins related to the VK cycle (ggcx, vkor), VK nuclear receptor (pxr), and VK-dependent proteins (VKDPs; oc1 and grp), were differentially expressed. This study highlights the potential benefits of increasing dietary VK levels in larval diets, and brings new insights on the mechanisms mediating the positive effects observed on larval performance and skeletal development.

Insights into electrosensory organ development, physiology and evolution from a lateral line-enriched transcriptome

PubMed Central

Modrell, Melinda S; Lyne, Mike; Carr, Adrian R; Zakon, Harold H; Buckley, David; Campbell, Alexander S; Davis, Marcus C; Micklem, Gos; Baker, Clare VH

2017-01-01

The anamniote lateral line system, comprising mechanosensory neuromasts and electrosensory ampullary organs, is a useful model for investigating the developmental and evolutionary diversification of different organs and cell types. Zebrafish neuromast development is increasingly well understood, but neither zebrafish nor Xenopus is electroreceptive and our molecular understanding of ampullary organ development is rudimentary. We have used RNA-seq to generate a lateral line-enriched gene-set from late-larval paddlefish (Polyodon spathula). Validation of a subset reveals expression in developing ampullary organs of transcription factor genes critical for hair cell development, and genes essential for glutamate release at hair cell ribbon synapses, suggesting close developmental, physiological and evolutionary links between non-teleost electroreceptors and hair cells. We identify an ampullary organ-specific proneural transcription factor, and candidates for the voltage-sensing L-type Cav channel and rectifying Kv channel predicted from skate (cartilaginous fish) ampullary organ electrophysiology. Overall, our results illuminate ampullary organ development, physiology and evolution. DOI: http://dx.doi.org/10.7554/eLife.24197.001 PMID:28346141

Nonconsumptive effects of predatory Chrysomya rufifacies (Diptera: Calliphoridae) larval cues on larval Cochliomyia macellaria (Diptera: Calliphoridae) growth and development

USDA-ARS?s Scientific Manuscript database

Forensic entomologists often rely on development data associated with a given species to estimate when it colonized human or other vertebrate remains. In most instances, these development studies are based on single species reared in isolation in the laboratory. This study examined the impact of e...

Oyster larval transport in coastal Alabama: Dominance of physical transport over biological behavior in a shallow estuary

NASA Astrophysics Data System (ADS)

Kim, Choong-Ki; Park, Kyeong; Powers, Sean P.; Graham, William M.; Bayha, Keith M.

2010-10-01

Among the various factors affecting recruitment of marine invertebrates and fish, larval transport may produce spatial and temporal patterns of abundance that are important determinants of management strategies. Here we conducted a field and modeling study to investigate the larval transport of eastern oyster, Crassostrea virginica, in Mobile Bay and eastern Mississippi Sound, Alabama. A three-dimensional larval transport model accounting for physical transport, biological movement of larvae, and site- and larval-specific conditions was developed. A hydrodynamic model was used to simulate physical transport, and biological movement was parameterized as a function of swimming and sinking velocity of oyster larvae. Site- and larval-specific conditions, including spawning location, spawning stock size, spawning time, and larval period, were determined based on the previous studies. The model reasonably reproduced the observed gradient in oyster spat settlement and bivalve larval concentration, although the model results were less dynamic than the data, probably owing to the simplified biological conditions employed in the model. A persistent gradient decreasing from west to east in the model results at time scales of overall average, season, and each survey in 2006 suggests that the larval supply may be responsible for the corresponding gradient in oyster spat settlement observed over the past 40 years. Biological movement increased larval retention near the spawning area, thus providing a favorable condition for local recruitment of oysters. Inclusion of biological movement, however, caused little change in the overall patterns of larval transport and still resulted in a west-east gradient, presumably because of frequent destratification in the shallow Mobile Bay system.

The geometric framework for nutrition reveals interactions between protein and carbohydrate during larval growth in honey bees

PubMed Central

Slater, Garett P.; Rajamohan, Arun; Yocum, George D.; Greenlee, Kendra J.; Bowsher, Julia H.

2017-01-01

ABSTRACT In holometabolous insects, larval nutrition affects adult body size, a life history trait with a profound influence on performance and fitness. Individual nutritional components of larval diets are often complex and may interact with one another, necessitating the use of a geometric framework for elucidating nutritional effects. In the honey bee, Apis mellifera, nurse bees provision food to developing larvae, directly moderating growth rates and caste development. However, the eusocial nature of honey bees makes nutritional studies challenging, because diet components cannot be systematically manipulated in the hive. Using in vitro rearing, we investigated the roles and interactions between carbohydrate and protein content on larval survival, growth, and development in A. mellifera. We applied a geometric framework to determine how these two nutritional components interact across nine artificial diets. Honey bees successfully completed larval development under a wide range of protein and carbohydrate contents, with the medium protein (∼5%) diet having the highest survival. Protein and carbohydrate both had significant and non-linear effects on growth rate, with the highest growth rates observed on a medium-protein, low-carbohydrate diet. Diet composition did not have a statistically significant effect on development time. These results confirm previous findings that protein and carbohydrate content affect the growth of A. mellifera larvae. However, this study identified an interaction between carbohydrate and protein content that indicates a low-protein, high-carb diet has a negative effect on larval growth and survival. These results imply that worker recruitment in the hive would decline under low protein conditions, even when nectar abundance or honey stores are sufficient. PMID:28396492

Development of the acoustically evoked behavioral response in larval plainfin midshipman fish, Porichthys notatus.

PubMed

Alderks, Peter W; Sisneros, Joseph A

2013-01-01

The ontogeny of hearing in fishes has become a major interest among bioacoustics researchers studying fish behavior and sensory ecology. Most fish begin to detect acoustic stimuli during the larval stage which can be important for navigation, predator avoidance and settlement, however relatively little is known about the hearing capabilities of larval fishes. We characterized the acoustically evoked behavioral response (AEBR) in the plainfin midshipman fish, Porichthys notatus, and used this innate startle-like response to characterize this species' auditory capability during larval development. Age and size of larval midshipman were highly correlated (r(2) = 0.92). The AEBR was first observed in larvae at 1.4 cm TL. At a size ≥ 1.8 cm TL, all larvae responded to a broadband stimulus of 154 dB re1 µPa or -15.2 dB re 1 g (z-axis). Lowest AEBR thresholds were 140-150 dB re 1 µPa or -33 to -23 dB re 1 g for frequencies below 225 Hz. Larval fish with size ranges of 1.9-2.4 cm TL had significantly lower best evoked frequencies than the other tested size groups. We also investigated the development of the lateral line organ and its function in mediating the AEBR. The lateral line organ is likely involved in mediating the AEBR but not necessary to evoke the startle-like response. The midshipman auditory and lateral line systems are functional during early development when the larvae are in the nest and the auditory system appears to have similar tuning characteristics throughout all life history stages.

Development of a meridic diet for Hylobius transversovittatus (Coleoptera: Curculionidae) and the role of carbohydrates in feeding, growth, and survival of larvae.

PubMed

Tomic-Carruthers, Nada

2007-08-01

The root-feeding weevil Hylobius transversovittatus Goeze (Coleoptera: Curculionidae) is used for biological control of the invasive plant purple loosestrife, Luthrum salicaria L. (Lythraceae). A simple rearing system for this weevil was developed with the goals of improving production techniques and increasing the availability of insects for field introduction. Additionally, the dietary effects of digestible and indigestible carbohydrates were explored. A meridic diet for rearing H. transversovittatus was formulated through nutritional alterations of a boll weevil, Anthonomus grandis grandis Boheman, diet. Diet attractiveness was evaluated on two levels: first, by recording the incidence of initial tunneling, and second, by estimating the larval establishment rate. The performance of test diet formulations was further assessed by measuring developmental and survival rates of H. transversovittatus. Sucrose, starch, and three types of indigestible carbohydrates were tested as components to improve diet performance. Physical properties of the diet, modified by fillers in test formulations, produced major effects on the initial tunneling of hatchlings. The establishment of hatchlings was affected by chemical properties of the diet. Increases in sucrose concentration decreased larval establishment, decreased the rate of larval development, and decreased larval survival. However, omitting sucrose from the diet, or replacing it with starch, increased mortality of first instars. In advanced stages of larval development, omitting sucrose from the diet did not significantly affect larval survival. The developmental rate of larvae was increased when the amount of digestible carbohydrate was reduced. To date, seven generations of the univoltine H. transversovittatus have been successfully produced on this new meridic diet.

Functional genomics identifies regulators of the phototransduction machinery in the Drosophila larval eye and adult ocelli.

PubMed

Mishra, Abhishek Kumar; Bargmann, Bastiaan O R; Tsachaki, Maria; Fritsch, Cornelia; Sprecher, Simon G

2016-02-15

Sensory perception of light is mediated by specialized Photoreceptor neurons (PRs) in the eye. During development all PRs are genetically determined to express a specific Rhodopsin (Rh) gene and genes mediating a functional phototransduction pathway. While the genetic and molecular mechanisms of PR development is well described in the adult compound eye, it remains unclear how the expression of Rhodopsins and the phototransduction cascade is regulated in other visual organs in Drosophila, such as the larval eye and adult ocelli. Using transcriptome analysis of larval PR-subtypes and ocellar PRs we identify and study new regulators required during PR differentiation or necessary for the expression of specific signaling molecules of the functional phototransduction pathway. We found that the transcription factor Krüppel (Kr) is enriched in the larval eye and controls PR differentiation by promoting Rh5 and Rh6 expression. We also identified Camta, Lola, Dve and Hazy as key genes acting during ocellar PR differentiation. Further we show that these transcriptional regulators control gene expression of the phototransduction cascade in both larval eye and adult ocelli. Our results show that PR cell type-specific transcriptome profiling is a powerful tool to identify key transcriptional regulators involved during several aspects of PR development and differentiation. Our findings greatly contribute to the understanding of how combinatorial action of key transcriptional regulators control PR development and the regulation of a functional phototransduction pathway in both larval eye and adult ocelli. Copyright © 2015 Elsevier Inc. All rights reserved.

Validation of a New Larval Rearing Unit for Aedes albopictus (Diptera: Culicidae) Mass Rearing

PubMed Central

Gilles, Jérémie R. L.; Bellini, Romeo

2014-01-01

The mosquito larval rearing unit developed at the Insect Pest Control Laboratory (IPCL) of the FAO/IAEA Joint Division was evaluated for its potential use for Aedes albopictus (Skuse, 1895) mass rearing in support of the development of a sterile insect technique (SIT) package for this species. The use of the mass rearing trays and rack did not adversely affect larval development, pupation and survival rates and allowed the management of large larval rearing colonies with reduced space requirements in comparison with classical individual trays. The effects of larval density, water temperature and diet composition on pupal production and size differentiation for sex separation efficacy were analyzed for individual mass rearing trays as well as multiple trays stacked within the dedicated rack unit. Best results were obtained using eighteen thousand larvae per tray at a density of 3 larvae per ml of deionized water at a temperature of 28°C on a diet consisting of 50% tuna meal, 36% bovine liver powder, 14% brewer's yeast and, as an additive, 0.2 gr of Vitamin Mix per 100 ml of diet solution. Pupae were harvested on the sixth day from larval introduction at L1 stage and males were separated out by the use of a 1400 µm sieve with 99.0% accuracy with a recovery rate of ca. 25% of the total available males. With the use of this larval rearing unit, an average production of 100,000 male pupae per week can be achieved in just 2 square meter of laboratory space. Compared to previous laboratory rearing method, the same pupal production and sex separation efficacy could only be achieved by use of ca. 200 plastic trays which required the space of two 5 square meter climatic-controlled rooms. PMID:24647347

EXPOSURE METHOD CONSIDERATIONS FOR MEASURING VITELLOGENIN EXPRESSION IN LARVAL AND MALE FATHEAD MINNOWS (PIMEPHALES PROMELAS)

EPA Science Inventory

Our laboratory has developed methods for measuring the expression of the vitellogenin (Vg) gene in larval and adult male fathead minnows. During this development we found several conditions that affect background Vg levels and we observed preconditions for the expression of this...

Relative abundance of tree hole-breeding mosquitoes in Boone County, Missouri, USA, with emphasis on the vector potential of Aedes triseriatus for canine heartworm, Dirofilaria immitis (Spirurida: Filariidae).

PubMed

Debboun, Mustapha; Green, Theodore J; Rueda, Leopoldo M; Hall, Robert D

2005-09-01

Aedes (Protomacleaya) triseriatus currently shares its habitat in the USA with the introduced species Aedes (Finlaya) japonicus and Aedes (Stegomyia) albopictus. In the late 1980s, before the introduction of these 2 species, Ae. triseriatus was the dominant tree hole- and artificial container-breeding mosquito in central Missouri. Aedes triseriatus represented 89% of the mosquito immatures collected from water-filled tree holes and artificial containers at 3 forested field sites in central Missouri, from May to October, 1986 to 1988. Laboratory-reared female Ae. triseriatus were able to support larval development of Dirofilaria immitis (canine heartworm) to the infective 3rd larval stage. A blood meal from a microfilaremic Collie-mix dog was sufficient to infect adult female mosquitoes, indicating that Ae. triseriatus is a possible vector of canine heartworm in central Missouri. Confirmation of the vector status of this species depends on the yet-to-be observed transmission of D. immitis by Ae. triseriatus in the field, possibly by experimental infection of dogs by wild-caught mosquitoes. Defining the role of this species in epizootic outbreaks could contribute toward accurate risk assessment as the abundance of Ae. triseriatus increases and decreases in response to the success of Ae. albopictus, Ae. japonicus, or other introduced container-breeding mosquitoes.

Predator-induced larval cloning in the sand dollar Dendraster excentricus: might mothers matter?

PubMed

Vaughn, Dawn

2009-10-01

Predator-induced cloning in echinoid larvae, with reduced size a consequence of cloning, is a dramatic modification of development and a novel response to risks associated with prolonged planktonic development. Recent laboratory studies demonstrate that exposure to stimuli from predators (i.e., fish mucus) induces cloning in the pluteus larvae (plutei) of Dendraster excentricus. However, the timing and incidence of cloning and size reduction of unrelated conspecific plutei differed across experiments. A variable cloning response suggests the effects of such factors as cue quality, egg provisioning, maternal experience, and genetic background, indicating that the potential advantages of cloning as an adaptive response to predators are not available to all larvae. This study tested the hypothesis that cloning in D. excentricus plutei is maternally influenced. Plutei from three half-sibling larval families (different mothers, same father) were exposed to fish mucus for 9 days during early development. Cloning was inferred in a percentage of plutei from each family; however, the rate and success of cloning differed significantly among the larval half-siblings. Unexpectedly, all mucus-treated plutei were smaller and developmentally delayed when compared to all plutei reared in the absence of a mucus stimulus. Thus, while the results from this study support the hypothesis of an influence of mothers on cloning of larval offspring, reduced larval size was a uniform response to fish mucus and did not indicate an effect of mothers. Hypotheses of the developmental effects of fish mucus on larval size with or without successful cloning are discussed.

Efficiency of three diets for larval development in mass rearing Aedes albopictus (Diptera: Culicidae).

PubMed

Puggioli, Arianna; Balestrino, F; Damiens, D; Lees, R S; Soliban, S M; Madakacherry, O; Dindo, M L; Bellini, R; Gilles, J R L

2013-07-01

A fundamental step in establishing a mass production system is the development of a larval diet that promotes high adult performance at a reasonable cost. To identify a suitable larval diet for Aedes albopictus (Skuse), three diets were compared: a standard laboratory diet used at the Centro Agricoltura Ambiente, Italy (CAA) and two diets developed specifically for mosquito mass rearing at the FAO/IAEA Laboratory, Austria. The two IAEA diets, without affecting survival to the pupal stage, resulted in a shorter time to pupation and to emergence when compared with the CAA diet. At 24 h from pupation onset, 50 and 90% of the male pupae produced on the CAA and IAEA diets, respectively, had formed and could be collected. The diet received during the larval stage affected the longevity of adult males with access to water only, with best results observed when using the CAA larval diet. However, similar longevity among diet treatments was observed when males were supplied with sucrose solution. No differences were observed in the effects of larval diet on adult male size or female fecundity and fertility. Considering these results, along with the relative costs of the three diets, the IAEA 2 diet is found to be the preferred choice for mass rearing of Aedes albopictus, particularly if a sugar meal can be given to adult males before release, to ensure their teneral reserves are sufficient for survival, dispersal, and mating in the field.

Nutritional and non-nutritional food components modulate phenotypic variation but not physiological trade-offs in an insect.

PubMed

Pascacio-Villafán, Carlos; Williams, Trevor; Birke, Andrea; Aluja, Martín

2016-07-12

Our understanding of how food modulates animal phenotypes and mediate trade-offs between life-history traits has benefited greatly from the study of combinations of nutritional and non-nutritional food components, such as plant secondary metabolites. We used a fruit fly pest, Anastrepha ludens, to examine phenotypic variation across larval, pupal and adult stages as a function of larval food with varying nutrient balance and content of chlorogenic acid, a secondary metabolite. Larval insects that fed on carbohydrate-biased diets relative to protein exhibited longer larval and pupal developmental periods, were often heavier as pupae and resisted desiccation and starvation for longer periods in the adult stage than insects fed on highly protein-biased diets. Except for a potential conflict between pupal development time and adult desiccation and starvation resistance, we did not detect physiological trade-offs mediated by the nutritional balance in larval food. Chlorogenic acid affected A. ludens development in a concentration and nutrient-dependent manner. Nutrients and host plant secondary metabolites in the larval diet induced changes in A. ludens phenotype and could influence fruit fly ecological interactions. We provide a unique experimental and modelling approach useful in generating predictive models of life history traits in a variety of organisms.

Nutritional and non-nutritional food components modulate phenotypic variation but not physiological trade-offs in an insect

PubMed Central

Pascacio-Villafán, Carlos; Williams, Trevor; Birke, Andrea; Aluja, Martín

2016-01-01

Our understanding of how food modulates animal phenotypes and mediate trade-offs between life-history traits has benefited greatly from the study of combinations of nutritional and non-nutritional food components, such as plant secondary metabolites. We used a fruit fly pest, Anastrepha ludens, to examine phenotypic variation across larval, pupal and adult stages as a function of larval food with varying nutrient balance and content of chlorogenic acid, a secondary metabolite. Larval insects that fed on carbohydrate-biased diets relative to protein exhibited longer larval and pupal developmental periods, were often heavier as pupae and resisted desiccation and starvation for longer periods in the adult stage than insects fed on highly protein-biased diets. Except for a potential conflict between pupal development time and adult desiccation and starvation resistance, we did not detect physiological trade-offs mediated by the nutritional balance in larval food. Chlorogenic acid affected A. ludens development in a concentration and nutrient-dependent manner. Nutrients and host plant secondary metabolites in the larval diet induced changes in A. ludens phenotype and could influence fruit fly ecological interactions. We provide a unique experimental and modelling approach useful in generating predictive models of life history traits in a variety of organisms. PMID:27406923

Determination of the efficiency of diets for larval development in mass rearing Aedes aegypti (Diptera: Culicidae).

PubMed

Gunathilaka, P A D H N; Uduwawala, U M H U; Udayanga, N W B A L; Ranathunge, R M T B; Amarasinghe, L D; Abeyewickreme, W

2017-11-23

Larval diet quality and rearing conditions have a direct and irreversible effect on adult traits. Therefore, the current study was carried out to optimize the larval diet for mass rearing of Aedes aegypti, for Sterile Insect Technique (SIT)-based applications in Sri Lanka. Five batches of 750 first instar larvae (L 1) of Ae. aegypti were exposed to five different concentrations (2-10%) of International Atomic Energy Agency (IAEA) recommended the larval diet. Morphological development parameters of larva, pupa, and adult were detected at 24 h intervals along with selected growth parameters. Each experiment was replicated five times. General Linear Modeling along with Pearson's correlation analysis were used for statistical treatments. Significant differences (P < 0.05) among the larvae treated with different concentrations were found using General Linear Modeling in all the stages namely: total body length and the thoracic length of larvae; cephalothoracic length and width of pupae; thoracic length, thoracic width, abdominal length and the wing length of adults; along with pupation rate and success, sex ratio, adult success, fecundity and hatching rate of Ae. aegypti. The best quality adults can be produced at larval diet concentration of 10%. However, the 8% larval diet concentration was most suitable for adult male survival.

Identification of mosquito larval habitats in high resolution satellite data

NASA Astrophysics Data System (ADS)

Kiang, Richard K.; Hulina, Stephanie M.; Masuoka, Penny M.; Claborn, David M.

2003-09-01

Mosquito-born infectious diseases are a serious public health concern, not only for the less developed countries, but also for developed countries like the U.S. Larviciding is an effective method for vector control and adverse effects to non-target species are minimized when mosquito larval habitats are properly surveyed and treated. Remote sensing has proven to be a useful technique for large-area ground cover mapping, and hence, is an ideal tool for identifying potential larval habitats. Locating small larval habitats, however, requires data with very high spatial resolution. Textural and contextual characteristics become increasingly evident at higher spatial resolution. Per-pixel classification often leads to suboptimal results. In this study, we use pan-sharpened Ikonos data, with a spatial resolution approaching 1 meter, to classify potential mosquito larval habitats for a test site in South Korea. The test site is in a predominantly agricultural region. When spatial characteristics were used in conjunction with spectral data, reasonably good classification accuracy was obtained for the test site. In particular, irrigation and drainage ditches are important larval habitats but their footprints are too small to be detected with the original spectral data at 4-meter resolution. We show that the ditches are detectable using automated classification on pan-sharpened data.

Growth performance and feed conversion efficiency of three edible mealworm species (Coleoptera: Tenebrionidae) on diets composed of organic by-products.

PubMed

van Broekhoven, Sarah; Oonincx, Dennis G A B; van Huis, Arnold; van Loon, Joop J A

2015-02-01

Insects receive increasing attention as an alternative protein-rich food source for humans. Producing edible insects on diets composed of organic by-products could increase sustainability. In addition, insect growth rate and body composition, and hence nutritional quality, can be altered by diet. Three edible mealworm species Tenebrio molitor L., Zophobas atratus Fab. and Alphitobius diaperinus Panzer were grown on diets composed of organic by-products originating from beer brewing, bread/cookie baking, potato processing and bioethanol production. Experimental diets differed with respect to protein and starch content. Larval growth and survival was monitored. Moreover, effects of dietary composition on feed conversion efficiency and mealworm crude protein and fatty acid profile were assessed. Diet affected mealworm development and feed conversion efficiency such that diets high in yeast-derived protein appear favourable, compared to diets used by commercial breeders, with respect to shortening larval development time, reducing mortality and increasing weight gain. Diet also affected the chemical composition of mealworms. Larval protein content was stable on diets that differed 2-3-fold in protein content, whereas dietary fat did have an effect on larval fat content and fatty acid profile. However, larval fatty acid profile did not necessarily follow the same trend as dietary fatty acid composition. Diets that allowed for fast larval growth and low mortality in this study led to a comparable or less favourable n6/n3 fatty acid ratio compared to control diets used by commercial breeders. In conclusion, the mealworm species used in this study can be grown successfully on diets composed of organic by-products. Diet composition did not influence larval protein content, but did alter larval fat composition to a certain extent. Copyright © 2015 Elsevier Ltd. All rights reserved.

dSet1 Is the Main H3K4 Di- and Tri-Methyltransferase Throughout Drosophila Development

PubMed Central

Hallson, Graham; Hollebakken, Robert E.; Li, Taosui; Syrzycka, Monika; Kim, Inho; Cotsworth, Shawn; Fitzpatrick, Kathleen A.; Sinclair, Donald A. R.; Honda, Barry M.

2012-01-01

In eukaryotes, the post-translational addition of methyl groups to histone H3 lysine 4 (H3K4) plays key roles in maintenance and establishment of appropriate gene expression patterns and chromatin states. We report here that an essential locus within chromosome 3L centric heterochromatin encodes the previously uncharacterized Drosophila melanogaster ortholog (dSet1, CG40351) of the Set1 H3K4 histone methyltransferase (HMT). Our results suggest that dSet1 acts as a “global” or general H3K4 di- and trimethyl HMT in Drosophila. Levels of H3K4 di- and trimethylation are significantly reduced in dSet1 mutants during late larval and post-larval stages, but not in animals carrying mutations in genes encoding other well-characterized H3K4 HMTs such as trr, trx, and ash1. The latter results suggest that Trr, Trx, and Ash1 may play more specific roles in regulating key cellular targets and pathways and/or act as global H3K4 HMTs earlier in development. In yeast and mammalian cells, the HMT activity of Set1 proteins is mediated through an evolutionarily conserved protein complex known as Complex of Proteins Associated with Set1 (COMPASS). We present biochemical evidence that dSet1 interacts with members of a putative Drosophila COMPASS complex and genetic evidence that these members are functionally required for H3K4 methylation. Taken together, our results suggest that dSet1 is responsible for the bulk of H3K4 di- and trimethylation throughout Drosophila development, thus providing a model system for better understanding the requirements for and functions of these modifications in metazoans. PMID:22048023

Morphological identification and COI barcodes of adult flies help determine species identities of chironomid larvae (Diptera, Chironomidae).

PubMed

Failla, A J; Vasquez, A A; Hudson, P; Fujimoto, M; Ram, J L

2016-02-01

Establishing reliable methods for the identification of benthic chironomid communities is important due to their significant contribution to biomass, ecology and the aquatic food web. Immature larval specimens are more difficult to identify to species level by traditional morphological methods than their fully developed adult counterparts, and few keys are available to identify the larval species. In order to develop molecular criteria to identify species of chironomid larvae, larval and adult chironomids from Western Lake Erie were subjected to both molecular and morphological taxonomic analysis. Mitochondrial cytochrome c oxidase I (COI) barcode sequences of 33 adults that were identified to species level by morphological methods were grouped with COI sequences of 189 larvae in a neighbor-joining taxon-ID tree. Most of these larvae could be identified only to genus level by morphological taxonomy (only 22 of the 189 sequenced larvae could be identified to species level). The taxon-ID tree of larval sequences had 45 operational taxonomic units (OTUs, defined as clusters with >97% identity or individual sequences differing from nearest neighbors by >3%; supported by analysis of all larval pairwise differences), of which seven could be identified to species or 'species group' level by larval morphology. Reference sequences from the GenBank and BOLD databases assigned six larval OTUs with presumptive species level identifications and confirmed one previously assigned species level identification. Sequences from morphologically identified adults in the present study grouped with and further classified the identity of 13 larval OTUs. The use of morphological identification and subsequent DNA barcoding of adult chironomids proved to be beneficial in revealing possible species level identifications of larval specimens. Sequence data from this study also contribute to currently inadequate public databases relevant to the Great Lakes region, while the neighbor-joining analysis reported here describes the application and confirmation of a useful tool that can accelerate identification and bioassessment of chironomid communities.

Morphological identification and COI barcodes of adult flies help determine species identities of chironomid larvae (Diptera, Chironomidae)

USGS Publications Warehouse

Failla, Andrew Joseph; Vasquez, Adrian Amelio; Hudson, Patrick L.; Fujimoto, Masanori; Ram, Jeffrey L.

2016-01-01

Establishing reliable methods for the identification of benthic chironomid communities is important due to their significant contribution to biomass, ecology and the aquatic food web. Immature larval specimens are more difficult to identify to species level by traditional morphological methods than their fully developed adult counterparts, and few keys are available to identify the larval species. In order to develop molecular criteria to identify species of chironomid larvae, larval and adult chironomids from Western Lake Erie were subjected to both molecular and morphological taxonomic analysis. Mitochondrial cytochrome c oxidase I (COI) barcode sequences of 33 adults that were identified to species level by morphological methods were grouped with COI sequences of 189 larvae in a neighbor-joining taxon-ID tree. Most of these larvae could be identified only to genus level by morphological taxonomy (only 22 of the 189 sequenced larvae could be identified to species level). The taxon-ID tree of larval sequences had 45 operational taxonomic units (OTUs, defined as clusters with >97% identity or individual sequences differing from nearest neighbors by >3%; supported by analysis of all larval pairwise differences), of which seven could be identified to species or ‘species group’ level by larval morphology. Reference sequences from the GenBank and BOLD databases assigned six larval OTUs with presumptive species level identifications and confirmed one previously assigned species level identification. Sequences from morphologically identified adults in the present study grouped with and further classified the identity of 13 larval OTUs. The use of morphological identification and subsequent DNA barcoding of adult chironomids proved to be beneficial in revealing possible species level identifications of larval specimens. Sequence data from this study also contribute to currently inadequate public databases relevant to the Great Lakes region, while the neighbor-joining analysis reported here describes the application and confirmation of a useful tool that can accelerate identification and bioassesment of chironomid communities.

Embryo-larval toxicity tests with the African catfish (Clarias gariepinus): comparative sensitivity of endpoints.

PubMed

Nguyen, L T H; Janssen, C R

2002-02-01

Embryo-larval toxicity tests with the African catfish (Clarias gariepinus) were performed to assess the comparative sensitivity of different endpoints. Measured test responses included embryo and larval survival, hatching, morphological development, and larval growth. Chromium, cadmium, copper, sodium pentachlorphenol (NaPCP), and malathion were used as model toxicants. Hatching was not affected by any of the chemicals tested, and embryo survival was only affected by chromium at > or = 36 mg/L. The growth of larvae was significantly reduced at > or = 11 mg/L Cr, > or = 0.63 mg/L Cu, > or = 0.03 mg/L NaPCP, and > or = 1.25 mg/L malathion. Morphological development of C. gariepinus was affected by all of the toxicants tested. Different types of morphological aberrations were observed, i.e., reduction of pigmentation in fish exposed to cadmium and copper, yolk sac edema in fish exposed to NaPCP and malathion, and deformation of the notochord in fish exposed to chromium and malathion. The sensitivity of the endpoints measured can be summarized as follows: growth > abnormality > larval survival > embryo survival > hatching.

Regulation of Aedes aegypti Population Dynamics in Field Systems: Quantifying Direct and Delayed Density Dependence

PubMed Central

Walsh, Rachael K.; Aguilar, Cristobal L.; Facchinelli, Luca; Valerio, Laura; Ramsey, Janine M.; Scott, Thomas W.; Lloyd, Alun L.; Gould, Fred

2013-01-01

Transgenic strains of Aedes aegypti have been engineered to help control transmission of dengue virus. Although resources have been invested in developing the strains, we lack data on the ecology of mosquitoes that could impact the success of this approach. Although studies of intra-specific competition have been conducted using Ae. aegypti larvae, none of these studies examine mixed age cohorts at densities that occur in the field, with natural nutrient levels. Experiments were conducted in Mexico to determine the impact of direct and delayed density dependence on Ae. aegypti populations. Natural water, food, and larval densities were used to estimate the impacts of density dependence on larval survival, development, and adult body size. Direct and delayed density-dependent factors had a significant impact on larval survival, larval development, and adult body size. These results indicate that control methods attempting to reduce mosquito populations may be counteracted by density-dependent population regulation. PMID:23669230

Social coercion of larval development in an ant species

NASA Astrophysics Data System (ADS)

Villalta, Irene; Amor, Fernando; Cerdá, Xim; Boulay, Raphaël

2016-04-01

Ants provide one of the best examples of the division of labor in animal societies. While the queens reproduce, workers generally refrain from laying eggs and dedicate themselves exclusively to domestic tasks. In many species, the small diploid larvae are bipotent and can develop either into workers or queens depending mostly on environmental cues. This generates a conflicting situation between the adults that tend to rear a majority of larvae into workers and the larvae whose individual interest may be to develop into reproductive queens. We tested the social regulation of larval caste fate in the fission-performing ant Aphaenogaster senilis. We first observed interactions between resident workers and queen- and worker-destined larvae in presence/absence of the queen. The results show that workers tend to specifically eliminate queen-destined larvae when the queen is present but not when she is absent or imprisoned in a small cage allowing for volatile pheromone exchanges. In addition, we found that the presence of already developed queen-destined larvae does not inhibit the development of younger still bipotent larvae into queens. Finally, we analyzed the cuticular hydrocarbon profiles of queen- and worker-destined larvae and found no significant quantitative or qualitative difference. Interestingly, the total amount of hydrocarbons on both larval castes is extremely low, which lends credence on the chemical insignificance hypothesis of larval ants. Overall, our results suggest that workers control larval development and police larvae that would develop into queens instead of workers. Such policing behavior is similar in many aspects to what is known of worker policing among adults.

Combining Google Earth and GIS mapping technologies in a dengue surveillance system for developing countries

PubMed Central

Chang, Aileen Y; Parrales, Maria E; Jimenez, Javier; Sobieszczyk, Magdalena E; Hammer, Scott M; Copenhaver, David J; Kulkarni, Rajan P

2009-01-01

Background Dengue fever is a mosquito-borne illness that places significant burden on tropical developing countries with unplanned urbanization. A surveillance system using Google Earth and GIS mapping technologies was developed in Nicaragua as a management tool. Methods and Results Satellite imagery of the town of Bluefields, Nicaragua captured from Google Earth was used to create a base-map in ArcGIS 9. Indices of larval infestation, locations of tire dumps, cemeteries, large areas of standing water, etc. that may act as larval development sites, and locations of the homes of dengue cases collected during routine epidemiologic surveying were overlaid onto this map. Visual imagery of the location of dengue cases, larval infestation, and locations of potential larval development sites were used by dengue control specialists to prioritize specific neighborhoods for targeted control interventions. Conclusion This dengue surveillance program allows public health workers in resource-limited settings to accurately identify areas with high indices of mosquito infestation and interpret the spatial relationship of these areas with potential larval development sites such as garbage piles and large pools of standing water. As a result, it is possible to prioritize control strategies and to target interventions to highest risk areas in order to eliminate the likely origin of the mosquito vector. This program is well-suited for resource-limited settings since it utilizes readily available technologies that do not rely on Internet access for daily use and can easily be implemented in many developing countries for very little cost. PMID:19627614

Social coercion of larval development in an ant species.

PubMed

Villalta, Irene; Amor, Fernando; Cerdá, Xim; Boulay, Raphaël

2016-04-01

Ants provide one of the best examples of the division of labor in animal societies. While the queens reproduce, workers generally refrain from laying eggs and dedicate themselves exclusively to domestic tasks. In many species, the small diploid larvae are bipotent and can develop either into workers or queens depending mostly on environmental cues. This generates a conflicting situation between the adults that tend to rear a majority of larvae into workers and the larvae whose individual interest may be to develop into reproductive queens. We tested the social regulation of larval caste fate in the fission-performing ant Aphaenogaster senilis. We first observed interactions between resident workers and queen- and worker-destined larvae in presence/absence of the queen. The results show that workers tend to specifically eliminate queen-destined larvae when the queen is present but not when she is absent or imprisoned in a small cage allowing for volatile pheromone exchanges. In addition, we found that the presence of already developed queen-destined larvae does not inhibit the development of younger still bipotent larvae into queens. Finally, we analyzed the cuticular hydrocarbon profiles of queen- and worker-destined larvae and found no significant quantitative or qualitative difference. Interestingly, the total amount of hydrocarbons on both larval castes is extremely low, which lends credence on the chemical insignificance hypothesis of larval ants. Overall, our results suggest that workers control larval development and police larvae that would develop into queens instead of workers. Such policing behavior is similar in many aspects to what is known of worker policing among adults.

Ocean circulation drives heterogeneous recruitments and connectivity among coral populations on the North West Shelf of Australia

NASA Astrophysics Data System (ADS)

Feng, Ming; Colberg, Frank; Slawinski, Dirk; Berry, Oliver; Babcock, Russ

2016-12-01

The North West Shelf (NWS) of Australia features extensive and globally significant fringing coral reef ecosystems with high levels of endemism and consequently has received significant conservation efforts in the form of Marine Parks. The shelf circulation on the NWS is dominated by the southwestward-flowing Holloway Current during austral autumn-winter and by the northeastward monsoonal currents during austral summer. Intraseasonal Oscillation and short-term wind variability also influence advection processes on the NWS. These circulation processes are likely to determine demographic inter-dependencies among reef systems in the region, but the extent and spatial variability of the inter-dependence are not well understood. In this study, we used a 3-dimensional, hydrostatic, primitive equations model, to simulate the shelf circulation on the NWS at 1 km horizontal resolution during 2004-2009. We then used a particle tracking model based on the shelf circulation model to simulate larval dispersal in a representative coral species, Acropora millepora, among the 3430 coral reefs on the NWS during its autumn mass spawning. Model results predicted that settling larvae typically reach suitable reef within 10 days of spawning, with a predominantly southwestward tendency of transport. There was significant spatial heterogeneity in larval settlements and the Dampier Archipelago areas seemed to be more isolated from the rest of the NWS. Year-to-year variations of larval dispersals were sensitive to the seasonal and intraseasonal variations of alongshore winds: mass spawning in late March would expose the Dampier Archipelago area to the Holloway Current onset, resulting in it being an occasional source region of larval supply for the rest of the NWS to the southwest; intraseasonal northeastward wind pulses coinciding with the mass larval spawning would bring larvae from coastal regions to the Dampier Archipelago on rare occasions. By aggregating the reefs into 47 subregions, we estimated that the mean rate of self-seeding within the subregions (as a proportion of total supply) was 22% (range from 99% to < 1%). Subregions with high retention (as a proportion of total egg production) were not necessarily those with the highest levels of overall larval settlements. Such high "sink" subregions were also some of the most important "source" subregions. Most of the important source and sink subregions were found to be outside existing marine parks, however, existing marine parks did contain subregions with some of the highest levels of self-seeding and larval retention.

Post-Larval Developmental Trajectory of Zebrafish Fry is Altered by Exposure to T3 or T4 Analogues

EPA Science Inventory

The thyroid axis plays a key role in development. While the impacts of perturbing thyroid axis development and/or function are documented in embryonic and larval zebrafish, the effects on developmental milestones at later life stages are not well-delineated. To assess potential l...

Development of a larval diet for the South American fruit fly Anastrepha fraterculus (Diptera:Tephritidae)

USDA-ARS?s Scientific Manuscript database

Mass-rearing protocols must be developed. In particular, a cost-effective larval diet, to implement the sterile insect technique against Anastrepha fratercculus (Wiedemann). The key elements of this diet are the optimal nutrients and their concentrations, diet supports or bulking agents, and the pH ...

Properties of Orange-Pupa-Inducing Factor (OPIF) in the swallowtail butterfly, Papilio xuthus L.

PubMed

Yamanaka, Akira; Adachi, Miwa; Imai, Hiroshi; Uchiyama, Terumasa; Inoue, Moeko; Islam, A T M Fayezul; Kitazawa, Chisato; Endo, Katsuhiko

2006-03-01

Diapause pupae of the swallowtail butterfly Papilio xuthus L. exhibit diapause-green, orange and brownish-orange color polymorphism. Development of orange pupae involves a neuroendocrine factor inducing orange pupa (Orange-Pupa-Inducing Factor, OPIF), which is secreted from the head-thoracic region during late pharate pupal stages, in particular from the ganglia of short-day animals located posteriorly from the second thoracic ganglion2 (TG2). This report describes certain properties of OPIF using bioassays involving ligated abdomens of short-day pharate pupae. Localization of OPIF in the central nervous system of short-day larvae indicated that it was present predominantly in TG2, thoracic ganglion3 (TG3) and abdominal ganglion1 (AG1) complexes. OPIF activity in TG(2,3)-AG1 complexes was over two times higher than in the more posteriorely located ganglia. The developmental profile of OPIF in last instar short-day larvae revealed that OPIF activity in larval ganglia posterior to TG2 became gradually higher as larval growth proceeded, suggesting that OPIF might be accumulated in TG(2,3)-AG(1-7) complexes as larvae prepare for pupal molting. Furthermore, ligated abdomens of short-day larvae developed into pupae of an orange type when a 2% NaCl extract containing OPIF prepared from TG(2,3)-AG(1-7) complexes of long-day larvae was injected into ligated abdomens of short-day pharate pupae, indicating that OPIF is also present in long-day larvae. Additionally, a biochemical investigation using gel filtration chromatography showed that the molecular weight of OPIF was about 10 kDa.

On the morphology of the central nervous system in larval stages of Carcinus maenas L. (Decapoda, Brachyura)

NASA Astrophysics Data System (ADS)

Harzsch, S.; Dawirs, R. R.

1993-02-01

We investigated the morphology of the central nervous system throughout the larval development of Carcinus maenas. For that purpose single larvae were reared in the laboratory from hatching through metamorphosis. Complete series of whole mout semithin sections were obtained from individuals of all successive larval stages and analysed with a light microscope. Morphological feature and spatial arrangement of discernable neural cell clusters, fibre tracts and neuropile are described and compared with the adult pattern. We found that most of the morphological features characterizing the adult nervous system are already present in the zoea-1. Nevertheless, there are marked differences with respect to the arrangement of nerve cell bodies, organization of cerebral neuropile, and disposition of ganglia in the ventral nerve cord. It appears that complexity of the central nervous neuropile is selectively altered during postmetamorphotic development, probably reflecting adaptive changes of sensory-motor integration in response to behavioural maturation. In contrast, during larval development there was little change in the overall structural organization of the central nervous system despite some considerable growth. However, the transition from zoea-4 to megalopa brings about multiple fundamental changes in larval morphology and behavioural pattern. Since central nervous integration should properly adapt to the altered behavioural repertoire of the megalopa, it seems necessary to ask in which respect synaptic rearrangement might characterize development of the central nervous system.

Larval Population Density Alters Adult Sleep in Wild-Type Drosophila melanogaster but Not in Amnesiac Mutant Flies

PubMed Central

Chi, Michael W.; Griffith, Leslie C.; Vecsey, Christopher G.

2014-01-01

Sleep has many important biological functions, but how sleep is regulated remains poorly understood. In humans, social isolation and other stressors early in life can disrupt adult sleep. In fruit flies housed at different population densities during early adulthood, social enrichment was shown to increase subsequent sleep, but it is unknown if population density during early development can also influence adult sleep. To answer this question, we maintained Drosophila larvae at a range of population densities throughout larval development, kept them isolated during early adulthood, and then tested their sleep patterns. Our findings reveal that flies that had been isolated as larvae had more fragmented sleep than those that had been raised at higher population densities. This effect was more prominent in females than in males. Larval population density did not affect sleep in female flies that were mutant for amnesiac, which has been shown to be required for normal memory consolidation, adult sleep regulation, and brain development. In contrast, larval population density effects on sleep persisted in female flies lacking the olfactory receptor or83b, suggesting that olfactory signals are not required for the effects of larval population density on adult sleep. These findings show that population density during early development can alter sleep behavior in adulthood, suggesting that genetic and/or structural changes are induced by this developmental manipulation that persist through metamorphosis. PMID:25116571

Larval Population Density Alters Adult Sleep in Wild-Type Drosophila melanogaster but Not in Amnesiac Mutant Flies.

PubMed

Chi, Michael W; Griffith, Leslie C; Vecsey, Christopher G

2014-08-11

Sleep has many important biological functions, but how sleep is regulated remains poorly understood. In humans, social isolation and other stressors early in life can disrupt adult sleep. In fruit flies housed at different population densities during early adulthood, social enrichment was shown to increase subsequent sleep, but it is unknown if population density during early development can also influence adult sleep. To answer this question, we maintained Drosophila larvae at a range of population densities throughout larval development, kept them isolated during early adulthood, and then tested their sleep patterns. Our findings reveal that flies that had been isolated as larvae had more fragmented sleep than those that had been raised at higher population densities. This effect was more prominent in females than in males. Larval population density did not affect sleep in female flies that were mutant for amnesiac, which has been shown to be required for normal memory consolidation, adult sleep regulation, and brain development. In contrast, larval population density effects on sleep persisted in female flies lacking the olfactory receptor or83b, suggesting that olfactory signals are not required for the effects of larval population density on adult sleep. These findings show that population density during early development can alter sleep behavior in adulthood, suggesting that genetic and/or structural changes are induced by this developmental manipulation that persist through metamorphosis.

Trade-offs between larval survival and adult ornament development depend on predator regime in a territorial dragonfly.

PubMed

Moore, Michael P; Martin, Ryan A

2018-05-28

Trade-offs between juvenile survival and the development of sexually selected traits can cause ontogenetic conflict between life stages that constrains adaptive evolution. However, the potential for ecological interactions to alter the presence or strength of these trade-offs remains largely unexplored. Antagonistic selection over the accumulation and storage of resources could be one common cause of environment-specific trade-offs between life stages: higher condition may simultaneously enhance adult ornament development and increase juvenile vulnerability to predators. We tested this hypothesis in an ornamented dragonfly (Pachydiplax longipennis). Higher larval body condition indeed enhanced the initial development of its intrasexually selected wing coloration, but was opposed by viability selection in the presence of large aeshnid predators. In contrast, viability selection did not oppose larval body condition in pools when aeshnids were absent, and was not affected when we manipulated cannibalism risk. Trade-offs between larval survival and ornament development, mediated through the conflicting effects of body condition, therefore occurred only under high predation risk. We additionally characterized how body condition influences several traits associated with predator avoidance. Although body condition did not affect burst distance, it did increase larval abdomen size, potentially making larvae easier targets for aeshnid predators. As high body condition similarly increases vulnerability to predators in many other animals, predator-mediated costs of juvenile resource accumulation could be a common, environment-specific limitation on the elaboration of sexually selected traits.

Development of the Acoustically Evoked Behavioral Response in Larval Plainfin Midshipman Fish, Porichthys notatus

PubMed Central

Alderks, Peter W.; Sisneros, Joseph A.

2013-01-01

The ontogeny of hearing in fishes has become a major interest among bioacoustics researchers studying fish behavior and sensory ecology. Most fish begin to detect acoustic stimuli during the larval stage which can be important for navigation, predator avoidance and settlement, however relatively little is known about the hearing capabilities of larval fishes. We characterized the acoustically evoked behavioral response (AEBR) in the plainfin midshipman fish, Porichthys notatus, and used this innate startle-like response to characterize this species' auditory capability during larval development. Age and size of larval midshipman were highly correlated (r2 = 0.92). The AEBR was first observed in larvae at 1.4 cm TL. At a size ≥1.8 cm TL, all larvae responded to a broadband stimulus of 154 dB re1 µPa or −15.2 dB re 1 g (z-axis). Lowest AEBR thresholds were 140–150 dB re 1 µPa or −33 to −23 dB re 1 g for frequencies below 225 Hz. Larval fish with size ranges of 1.9–2.4 cm TL had significantly lower best evoked frequencies than the other tested size groups. We also investigated the development of the lateral line organ and its function in mediating the AEBR. The lateral line organ is likely involved in mediating the AEBR but not necessary to evoke the startle-like response. The midshipman auditory and lateral line systems are functional during early development when the larvae are in the nest and the auditory system appears to have similar tuning characteristics throughout all life history stages. PMID:24340003

Immature Stages of Spodoptera eridania (Lepidoptera: Noctuidae): Developmental Parameters and Host Plants

PubMed Central

Montezano, Débora Goulart; Specht, Alexandre; Sosa–Gómez, Daniel Ricardo; Roque–Specht, Vânia Ferreira; de Barros, Neiva Monteiro

2014-01-01

Abstract This study aimed to detail the temporal and morphological parameters of the immature stages of southern armyworm Spodoptera eridania (Stoll, 1782) with larvae feed on artificial diet, under controlled conditions (25 ± 1°C, 70 ± 10% relative humidity and 14-h photophase) and gather information about their larval host plants. The viability of the egg, larval, pupal, and prepupal stages was 97.82, 93.62, 96.42, and 97.03%, respectively. The average duration of the egg, larval, pupal, and pre–pupal stages was 4.00, 16.18, 1.58, and 9.17 d, respectively. During the larval stage, 43.44% of females passed through seven instars, observing that the female’s development was significant slower than males. The female larvae that developed through six and seven instars exhibited a mean growth rate of 1.52 and 1.44, respectively. Female pupae were significantly larger, exhibiting faster development than males. The rearing method proved to be adequate, providing more detailed observations of the biological cycle, especially at the larval stage, and resulting in an overall survival of almost 85%. Two hundred two plant species belonging to 58 families are listed as natural hosts for S. eridania , mainly including Asteraceae, Fabaceae, Solanaceae, Poaceae, Amaranthaceae, and Malvaceae. PMID:25525103

In vitro manipulation of gene expression in larval Schistosoma: a model for postgenomic approaches in Trematoda

PubMed Central

YOSHINO, TIMOTHY P.; DINGUIRARD, NATHALIE; DE MORAES MOURÃO, MARINA

2013-01-01

SUMMARY With rapid developments in DNA and protein sequencing technologies, combined with powerful bioinformatics tools, a continued acceleration of gene identification in parasitic helminths is predicted, potentially leading to discovery of new drug and vaccine targets, enhanced diagnostics and insights into the complex biology underlying host-parasite interactions. For the schistosome blood flukes, with the recent completion of genome sequencing and comprehensive transcriptomic datasets, there has accumulated massive amounts of gene sequence data, for which, in the vast majority of cases, little is known about actual functions within the intact organism. In this review we attempt to bring together traditional in vitro cultivation approaches and recent emergent technologies of molecular genomics, transcriptomics and genetic manipulation to illustrate the considerable progress made in our understanding of trematode gene expression and function during development of the intramolluscan larval stages. Using several prominent trematode families (Schistosomatidae, Fasciolidae, Echinostomatidae), we have focused on the current status of in vitro larval isolation/cultivation as a source of valuable raw material supporting gene discovery efforts in model digeneans that include whole genome sequencing, transcript and protein expression profiling during larval development, and progress made in the in vitro manipulation of genes and their expression in larval trematodes using transgenic and RNA interference (RNAi) approaches. PMID:19961646

Same but different: Larval development and gall-inducing process of a non-pollinating fig wasp compared to that of pollinating fig-wasps

NASA Astrophysics Data System (ADS)

Jansen-González, Sergio; Teixeira, Simone de Padua; Kjellberg, Finn; Pereira, Rodrigo A. Santinelo

2014-05-01

The receptacles of fig trees (Ficus spp.) can harbor a highly diversified and complex community of chalcid wasps. Functional groups of fig wasps (e.g. gallers, cleptoparasites and parasitoids) oviposit into the fig at different developmental stages, reflecting different feeding regimes for these insect larvae. There are few direct data available on larval feeding regimes and access to resources. We studied the gall induction and larval feeding strategy of an Idarnes (group flavicollis) species, a non-pollinating fig wasp (NPFW) associated to Ficus citrifolia P. Miller in Brazil. This Idarnes species shares with the pollinator characteristics such as time of oviposition, ovipositor insertion through flower and location of the egg inside plant ovaries. Nevertheless, we show that the gall induction differs considerably from that of the pollinating species. This Idarnes species relies on the induction of nucellus cell proliferation for gall formation and as the main larval resource. This strategy enables it to develop in both pollinated and unpollinated figs. The large differences between this NPFW and other fig wasps in how ovules are galled suggest that there are different ways to be a galler. A functional analysis of NPFW community structure may require descriptions of the histological processes associated with larval development.

Patterns of Larval Sucker Emigration from the Sprague and Lower Williamson Rivers of the Upper Klamath Basin, Oregon, Prior to the Removal of Chiloquin Dam - 2006 Annual Report

USGS Publications Warehouse

Ellsworth, Craig M.; Tyler, Torrey J.; VanderKooi, Scott P.; Markle, Douglas F.

2009-01-01

In 2006, we collected larval Lost River sucker Deltistes luxatus (LRS), shortnose sucker Chasmistes brevirostris (SNS), and Klamath largescale sucker Catostomus snyderi (KLS) emigrating from spawning areas in the Williamson and Sprague Rivers. This work is part of a multi-year effort to characterize the relative abundance, drift timing, and length frequencies of larval suckers in this watershed prior to the removal of Chiloquin Dam on the lower Sprague River. Additional larval drift samples were collected from the Fremont Bridge on Lakeshore Drive on the south end of Upper Klamath Lake near its outlet to the Link River. Because of difficulties in distinguishing KLS larvae from SNS larvae, individuals identified as either of these two species were grouped together and reported as KLS-SNS in this report. We found that larval densities varied by site with the highest densities being collected at the most upstream site on the Sprague River at river kilometer (rkm) 108.0 near Beatty, Oregon (Beatty), and the most downstream sites near Chiloquin, Oregon; one site on the Sprague River at rkm 0.7 (Chiloquin) and the other site on the Williamson River at rkm 7.4 (Williamson). Larval catches were relatively small and sporadic at two other sites on the Sprague River located between Chiloquin and Beatty (Power Station at rkm 9.5 and Lone Pine at rkm 52.7) and one site on the Sycan River at rkm 4.7. Most larvae (79 percent) collected in 2006 were identified as LRS. More larvae and eggs were collected at Chiloquin than at any other site. The seasonal timing of larval drift varied by location; larvae generally were captured earlier at upstream sites than at downstream sites. Cumulative catch percentages of drifting larvae suggest that larval LRS emigrated earlier than KLS-SNS larvae at every site. Drift of LRS larvae at Beatty began 3 to 4 weeks earlier than at Chiloquin or Williamson. At Chiloquin, peak larval catches occurred 3 and 5 weeks after peak egg catches. The daily peak in larval drift at Chiloquin occurred approximately 1.5 to 2.0 hours after sunset. Nightly peak larval drift varied by location; larvae were captured earlier in the evening at sites closer to known spawning locations than sites farther away from these areas. The highest numerical catches of sucker-sized eggs were at Chiloquin indicating that this site is in close proximity to a spawning area. Numerical catches of older, more developed larval and juvenile suckers also were highest at Chiloquin. This may be due to the turbulent nature of this site, which could have swept larger fish into the drift. Proportional catches of older, more developed larval and juvenile suckers were highest at Sycan, Lone Pine, Power Station, and Fremont Bridge. This indicates these sites are located nearer to sucker nursery areas rather than spawning areas. Very few larval LRS were collected at Fremont Bridge at the south end of Upper Klamath Lake. Larval KLS-SNS densities at Fremont Bridge were the third highest of the seven sampling sites. Peak drift of larval KLS-SNS at Fremont Bridge occurred the week after peak drift of larval KLS-SNS at Williamson. Although inter-annual variation continues to appear in the larval drift data, our results continue to show consistent patterns of larval emigration in the drainage basin. In combination with data collected from the spawning movements and destinations of radio-tagged and PIT-tagged adult suckers, this larval drift data will provide a baseline standard by which to determine the effects of dam removal on the spawning distribution of endangered Klamath Basin suckers in the Sprague River.

Greenhouse Studies of Thiamethoxam Effects on Pea Leaf Weevil, Sitona lineatus

PubMed Central

Cárcamo, Héctor; Herle, Carolyn; Hervet, Vincent

2012-01-01

The pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae), has recently emerged as an important pest of field peas in the Canadian prairies. Systemic seed-coated insecticides may provide a tool for the integrated pest management of this pest. Therefore, several controlled assays were performed in order to determine effects of a recently registered neonicotinoid, (thiamethoxam) on S. lineatus damage to foliage, weevil mortality, fertility, egg viability, larval mortality, and root nodule damage. Foliage damage was reduced by thiamethoxam relative to untreated controls during the seedling stage (2nd–5th nodes), but weevil adult mortality was only 15–30%. Fertility was reduced substantially through an extra seven-day delay in the preoviposition period and reduced egg-laying rate during the first 20 days of the study (92% lower than controls). Overall egg viability was lower in females fed foliage grown from thiamethoxamtreated seeds. Larval survivorship and nodule damage were also lower, but only when eggs were added to treated plants at the 2nd node stage. When eggs were added late, at the 5th node stage, thiamethoxam had no effect on larval survivorship or nodule damage. The results of this study led to the conclusion that seed treatments such as thiamethoxam have potential to be used as tools that will aid in the integrated pest management of S. lineatus, especially in combination with other methods such as biocontrol and trap crops. PMID:23461362

Painted Goby Larvae under High-CO2 Fail to Recognize Reef Sounds.

PubMed

Castro, Joana M; Amorim, M Clara P; Oliveira, Ana P; Gonçalves, Emanuel J; Munday, Philip L; Simpson, Stephen D; Faria, Ana M

2017-01-01

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival.

Painted Goby Larvae under High-CO2 Fail to Recognize Reef Sounds

PubMed Central

Castro, Joana M.; Amorim, M. Clara P.; Oliveira, Ana P.; Gonçalves, Emanuel J.; Munday, Philip L.; Simpson, Stephen D.

2017-01-01

Atmospheric CO2 levels have been increasing at an unprecedented rate due to anthropogenic activity. Consequently, ocean pCO2 is increasing and pH decreasing, affecting marine life, including fish. For many coastal marine fishes, selection of the adult habitat occurs at the end of the pelagic larval phase. Fish larvae use a range of sensory cues, including sound, for locating settlement habitat. This study tested the effect of elevated CO2 on the ability of settlement-stage temperate fish to use auditory cues from adult coastal reef habitats. Wild late larval stages of painted goby (Pomatoschistus pictus) were exposed to control pCO2 (532 μatm, pH 8.06) and high pCO2 (1503 μatm, pH 7.66) conditions, likely to occur in nearshore regions subjected to upwelling events by the end of the century, and tested in an auditory choice chamber for their preference or avoidance to nighttime reef recordings. Fish reared in control pCO2 conditions discriminated reef soundscapes and were attracted by reef recordings. This behaviour changed in fish reared in the high CO2 conditions, with settlement-stage larvae strongly avoiding reef recordings. This study provides evidence that ocean acidification might affect the auditory responses of larval stages of temperate reef fish species, with potentially significant impacts on their survival. PMID:28125690

Antibiosis in Soybean Genotypes and the Resistance Levels to Spodoptera eridania (Cramer) (Lepidoptera: Noctuidae).

PubMed

Souza, B H S; Silva, A G; Janini, J C; Boica Júnior, A L

2014-12-01

The southern armyworm (SAW) Spodoptera eridania (Cramer) is one of the most common armyworm species defoliating soybeans. Preliminary screening trials have indicated that some soybean genotypes exhibit resistance to SAW. Therefore, in this study, we evaluated the development of SAW larvae fed on ten soybean genotypes in order to identify genotypes with antibiosis-type resistance. Neonate SAW larvae were daily fed with young leaves collected from plants at the vegetative growth stages V4-V5. Larval development and survival were recorded. Genotypes PI 227687 and PI 227682 delayed larval, pupal, and larva-adult development and yielded larvae with the lowest weight and survival and pupae with the lowest weight. Genotypes IAC 100 and DM 339 also negatively affected larval and pupal development and larval survival but at a lower level. Based on our results, the soybean lines PI 227687 and PI 227682 could be used as sources of genes for soybean breeding programs aiming to develop high yield, SAW-resistant cultivars. Moreover, further trials must be carried out under field conditions to validate if the commercial cultivars IAC 100 and DM 339, which expressed moderate levels of antibiosis-type resistance in the laboratory, are effective in suppressing SAW larvae populations.

The influence of spatially and temporally varying oceanographic conditions on meroplanktonic metapopulations

NASA Astrophysics Data System (ADS)

Botsford, L. W.; Moloney, C. L.; Hastings, A.; Largier, J. L.; Powell, T. M.; Higgins, K.; Quinn, J. F.

We synthesize the results of several modelling studies that address the influence of variability in larval transport and survival on the dynamics of marine metapopulations distributed along a coast. Two important benthic invertebrates in the California Current System (CCS), the Dungeness crab and the red sea urchin, are used as examples of the way in which physical oceanographic conditions can influence stability, synchrony and persistence of meroplanktonic metapopulations. We first explore population dynamics of subpopulations and metapopulations. Even without environmental forcing, isolated local subpopulations with density-dependence can vary on time scales roughly twice the generation time at high adult survival, shifting to annual time scales at low survivals. The high frequency behavior is not seen in models of the Dungeness crab, because of their high adult survival rates. Metapopulations with density-dependent recruitment and deterministic larval dispersal fluctuate in an asynchronous fashion. Along the coast, abundance varies on spatial scales which increase with dispersal distance. Coastwide, synchronous, random environmental variability tends to synchronize these metapopulations. Climate change could cause a long-term increase or decrease in mean larval survival, which in this model leads to greater synchrony or extinction respectively. Spatially managed metapopulations of red sea urchins go extinct when distances between harvest refugia become greater than the scale of larval dispersal. All assessments of population dynamics indicate that metapopulation behavior in general dependes critically on the temporal and spatial nature of larval dispersal, which is largely determined by physical oceanographic conditions. We therfore explore physical influences on larval dispersal patterns. Observed trends in temperature and salinity applied to laboratory-determined responses indicate that natural variability in temperature and salinity can lead to variability in larval development period on interannual (50%), intra-annual (20%) and latitudinal (200%) scales. Variability in development period significantly influences larval survival and, thus, net transport. Larval drifters that undertake diel vertical migration in a primitive equation model of coastal circulation (SPEM) demonstrate the importance of vertical migration in determining horizontal transport. Empirically derived estimates of the effects of wind forcing on larval transport of vertically migrating larvae (wind drift when near the surface and Ekman transport below the surface) match cross-shelf distributions in 4 years of existing larval data. We use a one-dimensional advection-diffusion model, which includes intra-annual timing of cross-shelf flows in the CCS, to explore the combined effects on settlement: (1) temperature- and salinity-dependent development and survival rates and (2) possible horizontal transport due to vertical migration of crab larvae. Natural variability in temperature, wind forcing, and the timing of the spring transition can cause the observed variability in recruitment. We conclude that understanding the dynamics of coastally distributed metapopulations in response to physically-induced variability in larval dispersal will be a critical step in assessing the effects of climate change on marine populations.

A comparison of honeybee (Apis mellifera) queen, worker and drone larvae by RNA-Seq.

PubMed

He, Xu-Jiang; Jiang, Wu-Jun; Zhou, Mi; Barron, Andrew B; Zeng, Zhi-Jiang

2017-11-06

Honeybees (Apis mellifera) have haplodiploid sex determination: males develop from unfertilized eggs and females develop from fertilized ones. The differences in larval food also determine the development of females. Here we compared the total somatic gene expression profiles of 2-day and 4-day-old drone, queen and worker larvae by RNA-Seq. The results from a co-expression network analysis on all expressed genes showed that 2-day-old drone and worker larvae were closer in gene expression profiles than 2-day-old queen larvae. This indicated that for young larvae (2-day-old) environmental factors such as larval diet have a greater effect on gene expression profiles than ploidy or sex determination. Drones had the most distinct gene expression profiles at the 4-day larval stage, suggesting that haploidy, or sex dramatically affects the gene expression of honeybee larvae. Drone larvae showed fewer differences in gene expression profiles at the 2-day and 4-day time points than the worker and queen larval comparisons (598 against 1190 and 1181), suggesting a different pattern of gene expression regulation during the larval development of haploid males compared to diploid females. This study indicates that early in development the queen caste has the most distinct gene expression profile, perhaps reflecting the very rapid growth and morphological specialization of this caste compared to workers and drones. Later in development the haploid male drones have the most distinct gene expression profile, perhaps reflecting the influence of ploidy or sex determination on gene expression. © 2017 Institute of Zoology, Chinese Academy of Sciences.

[Experimental study of the larval development of Hymenolepis stylosa (Rudolphi, 1809), Raillet, 1899 (Cestoda : cyelophyllidea) (author's transl)].

PubMed

Gabrion, C

1977-01-01

Comparative studies of the larval development of Hymenolepis stylosa Rudolphi, 1809 (Cestoda : Cyclophyllidea), a parasite of Corvid birds are undertaken from three insect species. The development in the beetle, Tenebrio molitor shows that the scolex differenciation occurs before the invagination of the metacestode in the cystic vesicle. The cercomer is long, narrow and flexuous. In the grasshopper, Lousta migratoria, the development is the same one but the scolex invaganation begins early. In another beetle, Dermestes frischi, the oncosphere is stopped in the gut-wall. The morphology and development of the cysticercoids of avian species of Hymenolepis, which have a well known life cycle, are similar. Studies on the structure of the larval stages of avian and mammal species of Hymenolepis seem necessary to find the relations between the different species of this genus.

Effect of Larval Competition on Extrinsic Incubation Period and Vectorial Capacity of Aedes albopictus for Dengue Virus.

PubMed

Bara, Jeffrey; Rapti, Zoi; Cáceres, Carla E; Muturi, Ephantus J

2015-01-01

Despite the growing awareness that larval competition can influence adult mosquito life history traits including susceptibility to pathogens, the net effect of larval competition on human risk of exposure to mosquito-borne pathogens remains poorly understood. We examined how intraspecific larval competition affects dengue-2 virus (DENV-2) extrinsic incubation period and vectorial capacity of its natural vector Aedes albopictus. Adult Ae. albopictus from low and high-larval density conditions were orally challenged with DENV-2 and then assayed for virus infection and dissemination rates following a 6, 9, or 12-day incubation period using real-time quantitative reverse transcription PCR. We then modeled the effect of larval competition on vectorial capacity using parameter estimates obtained from peer-reviewed field and laboratory studies. Larval competition resulted in significantly longer development times, lower emergence rates, and smaller adults, but did not significantly affect the extrinsic incubation period of DENV-2 in Ae. albopictus. Our vectorial capacity models suggest that the effect of larval competition on adult mosquito longevity likely has a greater influence on vectorial capacity relative to any competition-induced changes in vector competence. Furthermore, we found that large increases in the viral dissemination rate may be necessary to compensate for small competition-induced reductions in daily survivorship. Our results indicate that mosquito populations that experience stress from larval competition are likely to have a reduced vectorial capacity, even when susceptibility to pathogens is enhanced.

Effect of Larval Competition on Extrinsic Incubation Period and Vectorial Capacity of Aedes albopictus for Dengue Virus

PubMed Central

Bara, Jeffrey; Rapti, Zoi; Cáceres, Carla E.; Muturi, Ephantus J.

2015-01-01

Despite the growing awareness that larval competition can influence adult mosquito life history traits including susceptibility to pathogens, the net effect of larval competition on human risk of exposure to mosquito-borne pathogens remains poorly understood. We examined how intraspecific larval competition affects dengue-2 virus (DENV-2) extrinsic incubation period and vectorial capacity of its natural vector Aedes albopictus. Adult Ae. albopictus from low and high-larval density conditions were orally challenged with DENV-2 and then assayed for virus infection and dissemination rates following a 6, 9, or 12-day incubation period using real-time quantitative reverse transcription PCR. We then modeled the effect of larval competition on vectorial capacity using parameter estimates obtained from peer-reviewed field and laboratory studies. Larval competition resulted in significantly longer development times, lower emergence rates, and smaller adults, but did not significantly affect the extrinsic incubation period of DENV-2 in Ae. albopictus. Our vectorial capacity models suggest that the effect of larval competition on adult mosquito longevity likely has a greater influence on vectorial capacity relative to any competition-induced changes in vector competence. Furthermore, we found that large increases in the viral dissemination rate may be necessary to compensate for small competition-induced reductions in daily survivorship. Our results indicate that mosquito populations that experience stress from larval competition are likely to have a reduced vectorial capacity, even when susceptibility to pathogens is enhanced. PMID:25951173

Experimental evolution in Drosophila melanogaster: interaction of temperature and food quality selection regimes.

PubMed

Bochdanovits, Zoltán; de Jong, Gerdien

2003-08-01

In Drosophila, both the phenotypic and evolutionary effect of temperature on adult size involves alterations to larval resource processing and affects other life-history traits, that is, development time but most notably, larval survival. Therefore, thermal evolution of adult body size might not be independent of simultaneous adaptation of larval traits to resource availability. Using experimental evolution lines adapted to high and low temperatures at different levels of food, we show that selection pressures interact in shaping larval resource processing. Evolution on poor food invariably leads to lower resource acquisition suggesting a cost to feeding behavior. However, following low temperature selection, lower resource acquisition led to a higher adult body size, probably by more efficient allocation to growth. In contrast, following high temperature selection, low resource acquisition benefited larval survival, possibly by reducing feeding-associated costs. We show that evolved differences to larval resource processing provide a possible proximate mechanism to variation in a suite of correlated life-history traits during adaptation to different climates. The implication for natural populations is that in nature, thermal evolution drives populations to opposite ends of an adult size versus larval survival trade-off by altering resource processing, if resource availability is limited.

Larval competition of Chrysomya megacephala and Chrysomya rufifacies (Diptera: Calliphoridae): behavior and ecological studies of two blow fly species of forensic significance.

PubMed

Shiao, Shiuh-Feng; Yeh, Ta-Chuan

2008-07-01

Chrysomya megacephala and Chrysomya rufifacies are two predominant necrophagous species in Taiwan. Larvae of the latter can prey on other maggots, including that of their own species as facultative food. This facultative characteristic of C. rufifacies may enhance its competitive advantage over other maggots and could also change the situation of other coexisting colonies. In this study, these two species were colonized in the laboratory, and the main objective was to try to understand the effect of competition on larval development. According to our results, intraspecific competition mostly occurred as competition for food; when the rearing density was increased, larvae pupated earlier, resulting in a lighter adult dry weight. The tendencies were similar in both species, but C. megacephala developed smaller viable adults and had higher survivorship at high densities. Although C. rufifacies could use the food resource of cannibalism, its survivorship was still low. Our results also showed there were significant interactions between intraspecific competition and the density factor. However, with interspecific competition, the first-instar larvae of C. rufifacies invaded maggot masses of C. megacephala to feed together. The third instars of C. rufifacies were able to expel C. megacephala larvae from food by using a fleshy protrusion on their body surface; C. megacephala was usually forced to pupate earlier by shortening its larval stages. The results indicated that a temporary competitive advantage could only be obtained by C. rufifacies under a proper larval density. In addition, the effects on different larval stages, the responses to different competition intensities, and the temperature-dependent effects on interspecific competition are also discussed. In general, under mixed-species rearing at different temperatures and densities, larval duration, adult dry weight, and survivorship of both species decreased. However, our results did not completely agree with previous studies, and we suspect that the difference was partially caused by different experimental designs and different biological characters of different blow fly colonies. Our results also suggest that both the predation ability and defense or escape activity should be taken into account when evaluating larval competitive advantages. The durations of larval stages of these two species could be decreased by approximately 54 h when a single species was reared alone and food was limited; the largest reduction in larval duration, approximately 25 h in C. megacephala and 34 h in C. rufifacies, caused by interspecific competition was under a high larval density. In conclusion, competition decreased the larval duration of these two species by up to 2 d; this also draws attention to justifying the postmortem interval estimation of using larval developmental data when larval competition exists.

Patterning the dorsal longitudinal flight muscles (DLM) of Drosophila: insights from the ablation of larval scaffolds

NASA Technical Reports Server (NTRS)

Fernandes, J. J.; Keshishian, H.

1996-01-01

The six Dorsal Longitudinal flight Muscles (DLMs) of Drosophila develop from three larval muscles that persist into metamorphosis and serve as scaffolds for the formation of the adult fibers. We have examined the effect of muscle scaffold ablation on the development of DLMs during metamorphosis. Using markers that are specific to muscle and myoblasts we show that in response to the ablation, myoblasts which would normally fuse with the larval muscle, fuse with each other instead, to generate the adult fibers in the appropriate regions of the thorax. The development of these de novo DLMs is delayed and is reflected in the delayed expression of erect wing, a transcription factor thought to control differentiation events associated with myoblast fusion. The newly arising muscles express the appropriate adult-specific Actin isoform (88F), indicating that they have the correct muscle identity. However, there are frequent errors in the number of muscle fibers generated. Ablation of the larval scaffolds for the DLMs has revealed an underlying potential of the DLM myoblasts to initiate de novo myogenesis in a manner that resembles the mode of formation of the Dorso-Ventral Muscles, DVMs, which are the other group of indirect flight muscles. Therefore, it appears that the use of larval scaffolds is a superimposition on a commonly used mechanism of myogenesis in Drosophila. Our results show that the role of the persistent larval muscles in muscle patterning involves the partitioning of DLM myoblasts, and in doing so, they regulate formation of the correct number of DLM fibers.

DENSITY-DEPENDENT EVOLUTION OF LIFE-HISTORY TRAITS IN DROSOPHILA MELANOGASTER.

PubMed

Bierbaum, Todd J; Mueller, Laurence D; Ayala, Francisco J

1989-03-01

Populations of Drosophila melanogaster were maintained for 36 generations in r- and K-selected environments in order to test the life-history predictions of theories on density-dependent selection. In the r-selection environment, populations were reduced to low densities by density-independent adult mortality, whereas populations in the K-selection environment were maintained at their carrying capacity. Some of the experimental results support the predictions or r- and K-selection theory; relative to the r-selected populations, the K-selected populations evolved an increased larval-to-adult viability, larger body size, and longer development time at high larval densities. Mueller and Ayala (1981) found that K-selected populations also have a higher rate of population growth at high densities. Other predictions of the thoery are contradicted by the lack of differences between the r and K populations in adult longevity and fecundity and a slower rate of development for r-selected individuals at low densities. The differences between selected populations in larval survivorship, larval-to-adult development time, and adult body size are strongly dependent on larval density, and there is a significant interaction between populations and larval density for each trait. This manifests an inadequacy of the theory on r- and K-selection, which does not take into account such interactions between genotypes and environments. We describe mechanisms that may explain the evolution of preadult life-history traits in our experiment and discuss the need for changes in theories of density-dependent selection. © 1989 The Society for the Study of Evolution.

Larval spicules, cilia, and symmetry as remnants of indirect development in the direct developing sea urchin Heliocidaris erythrogramma.

PubMed

Emlet, R B

1995-02-01

Nonfeeding larvae of the echinoid Heliocidaris erythrogramma were raised in culture and examined for expression of a larval skeleton and for the arrangement of the ciliated band. Opaque larvae were fixed, cleared, and examined under polarized light for evidence of calcification. By 35 hr after fertilization (at 22 degrees C), a pair of triradiate spicules was present at the posterior end of the larvae. Each member of this pair formed a fenestrated spicule as it grew laterally. This pair and another pair which formed subsequently, were arranged across a plane of bilateral symmetry orthagonal to the juvenile oral aboral axis. These paired larval spicules can be identified as reduced expressions of postoral and posterodorsal rods found in plutei, and their expression indicates that the juvenile rudiment of H. erythrogramma forms on the left side and that larval body axes are conserved in this modified larva. By 44 hr the ciliated band formed as an incomplete transverse loop of three segments at the posterior end and on the dorsal surface of the ovoid larva. Cilia in these segments grew to lengths of 45-50 microns, longer than other swimming and feeding cilia reported for echinoderm larvae. Band segments are interpreted as expressions of epaulettes (specialized swimming bands) rather than the feeding ciliated band of the pluteus. The ciliated band segments and the larval spicules are both bilaterally symmetrical with respect to the same plane and indicate conserved larval bilateral symmetry despite the major asymmetry of the fates of cells on either side of this plane in their contribution to juvenile development.

Egg hatch and survival and development of beet webworm (Lepidoptera: Crambidae) larvae at different combinations of temperature and relative humidity

USDA-ARS?s Scientific Manuscript database

To understand the role that temperature and humidity play in the population dynamics of the beet webworm, Loxostege sticticalis L. (Lepidoptera: Crambidae), egg hatchability, survival of 1st - 5th instars, survival of the complete larval stage, survival curves, and larval development rates were inve...

Development of liquid larval diet with modified rearing system for Bactrocera dorsalis (Hendel) (Diptera:Tephritidae) for the application of sterile insect technique

USDA-ARS?s Scientific Manuscript database

A liquid larval diet and its rearing system have been developed for mass rearing of Bactrocera dorsalis (Hendel) in Hawaii. Rearing facility in Institute of Food and Radiation Biology, Atomic Energy Research Establishment, Dhaka, Bangladesh, modified protein source from brewer's yeast to a combinat...

GROWTH AND CHANGES IN BIOCHEMICAL COMPOSITION DURING LARVAL DEVELOPMENT OF THE STONE CRAB, MENIPPE ADINA WILLIAMS AND FELDER, 1986

EPA Science Inventory

Larval development in Menippe adina was associated with changes in weight and biochemical composition. Larvae of the stone crab, M. adina, were mass-reared under laboratory conditions (28|C; 20o/ooS) from hatching to the megalopal stage. Growth in M. adina is exponential througho...

Heterochronic developmental shift caused by thyroid hormone in larval sand dollars and its implications for phenotypic plasticity and the evolution of nonfeeding development.

PubMed

Heyland, Andreas; Hodin, Jason

2004-03-01

Recent work on a diverse array of echinoderm species has demonstrated, as is true in amphibians, that thyroid hormone (TH) accelerates development to metamorphosis. Interestingly, the feeding larvae of several species of sea urchins seem to obtain TH through their diet of planktonic algae (exogenous source), whereas nonfeeding larvae of the sand dollar Peronella japonica produce TH themselves (endogenous source). Here we examine the effects of TH (thyroxine) and a TH synthesis inhibitor (thiourea) on the development of Dendraster excentricus, a sand dollar with a feeding larva. We report reduced larval skeleton lengths and more rapid development of the juvenile rudiment in the exogenous TH treatments when compared to controls. Also, larvae treated with exogenous TH reached metamorphic competence faster at a significantly reduced juvenile size, representing the greatest reduction in juvenile size ever reported for an echinoid species with feeding larvae. These effects of TH on D. excentricus larval development are strikingly similar to the phenotypically plastic response of D. excentricus larvae reared under high food conditions. We hypothesize that exogenous (algae-derived) TH is the plasticity cue in echinoid larvae, and that the larvae use ingested TH levels as an indicator for larval nutrition, ultimately signaling the attainment of metamorphic competence. Furthermore, our experiments with the TH synthesis inhibitor thiourea indicate that D. excentricus larvae can produce some TH endogenously. Endogenous TH production might, therefore, be a shared feature among sand dollars, facilitating the evolution of nonfeeding larval development in that group. Mounting evidence on the effects of thyroid hormones in echinoderm development suggests life-history models need to incorporate metamorphic hormone effects and the evolution of metamorphic hormone production.

High expression of new genes in trochophore enlightening the ontogeny and evolution of trochozoans.

PubMed

Xu, Fei; Domazet-Lošo, Tomislav; Fan, Dingding; Dunwell, Thomas L; Li, Li; Fang, Xiaodong; Zhang, Guofan

2016-10-04

Animals with trochophore larvae belong to Trochozoa, one of the main branches of Bilateria. In addition to exhibiting spiral cleavage and early cell fate determination, trochozoans typically undergo indirect development, which contributes to the most unique characteristics of their ontogeny. The indirect development of trochozoans has provoked discussion regarding the origin and evolution of marine larvae and is interesting from the perspective of phylogeny-ontogeny correspondence. While these phylo-onto correlations have an hourglass shape in Deuterostomia, Ecdysozoa, plants and even fungi, they have seldom been studied in Trochozoa, and even Lophotrochozoa. Here, we compared the ontogenetic transcriptomes of the Pacific oyster, Crassostrea gigas (Bivalvia, Mollusca), the Pacific abalone, Haliotis discus hannai (Gastropoda, Mollusca), and the sand worm Perinereis aibuhitensis (Polychaeta, Annelida) using several complementary phylotranscriptomic methods to examine their evolutionary trajectories. The results revealed the late trochophore stage as the phylotypic phase. However, this basic pattern is accompanied with increased use of new genes in the trochophore stages which marks specific adaptations of the larval body plans.

Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

NASA Astrophysics Data System (ADS)

Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

1994-08-01

Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by intrduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spaceflight, and show that extensive degress of development can take place in this microgravity environment.

Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

NASA Technical Reports Server (NTRS)

Spooner, B. S.; Debell, L.; Armbrust, L.; Guikema, J. A.; Metcalf, J.; Paulsen, A.

1994-01-01

Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by introduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spa ceflight, and show that extensive degrees of development can take place in this microgravity environment.

Modeling larval connectivity of the Atlantic surfclams within the Middle Atlantic Bight: Model development, larval dispersal and metapopulation connectivity

NASA Astrophysics Data System (ADS)

Zhang, Xinzhong; Haidvogel, Dale; Munroe, Daphne; Powell, Eric N.; Klinck, John; Mann, Roger; Castruccio, Frederic S.

2015-02-01

To study the primary larval transport pathways and inter-population connectivity patterns of the Atlantic surfclam, Spisula solidissima, a coupled modeling system combining a physical circulation model of the Middle Atlantic Bight (MAB), Georges Bank (GBK) and the Gulf of Maine (GoM), and an individual-based surfclam larval model was implemented, validated and applied. Model validation shows that the model can reproduce the observed physical circulation patterns and surface and bottom water temperature, and recreates the observed distributions of surfclam larvae during upwelling and downwelling events. The model results show a typical along-shore connectivity pattern from the northeast to the southwest among the surfclam populations distributed from Georges Bank west and south along the MAB shelf. Continuous surfclam larval input into regions off Delmarva (DMV) and New Jersey (NJ) suggests that insufficient larval supply is unlikely to be the factor causing the failure of the population to recover after the observed decline of the surfclam populations in DMV and NJ from 1997 to 2005. The GBK surfclam population is relatively more isolated than populations to the west and south in the MAB; model results suggest substantial inter-population connectivity from southern New England to the Delmarva region. Simulated surfclam larvae generally drift for over one hundred kilometers along the shelf, but the distance traveled is highly variable in space and over time. Surfclam larval growth and transport are strongly impacted by the physical environment. This suggests the need to further examine how the interaction between environment, behavior, and physiology affects inter-population connectivity. Larval vertical swimming and sinking behaviors have a significant net effect of increasing larval drifting distances when compared with a purely passive model, confirming the need to include larval behavior.

Microbial larvicides for malaria control in The Gambia

PubMed Central

Majambere, Silas; Lindsay, Steven W; Green, Clare; Kandeh, Balla; Fillinger, Ulrike

2007-01-01

Background Mosquito larval control may prove to be an effective tool for incorporating into integrated vector management (IVM) strategies for reducing malaria transmission. Here the efficacy of microbial larvicides against Anopheles gambiae s.l. was tested in preparation for a large-scale larviciding programme in The Gambia. Methods The impact of water-dispersible (WDG) and corn granule (CG) formulations of commercial Bacillus sphaericus strain 2362 (Bs; VectoLex®) and Bacillus thuringiensis var.israelensis strain AM65-52 (Bti; VectoBac®) on larval development were tested under laboratory and field conditions to (1) identify the susceptibility of local vectors, (2) evaluate the residual effect and re-treatment intervals, (3) test the effectiveness of the microbials under operational application conditions and (4) develop a method for large-scale application. Results The major malaria vectors were highly susceptible to both microbials. The lethal concentration (LC) to kill 95% of third instar larvae of Anopheles gambiae s.s. after 24 hours was 0.023 mg/l (14.9 BsITU/l) for Bs WDG and 0.132 mg/l (396 ITU/l) for Bti WDG. In general Bs had little residual effect under field conditions even when the application rate was 200 times greater than the LC95. However, there was a residual effect up to 10 days in standardized field tests implemented during the dry season. Both microbials achieved 100% mortality of larvae 24–48 hours post-application but late instar larvae were detected 4 days after treatment. Pupae development was reduced by 94% (95% Confidence Interval = 90.8–97.5%) at weekly re-treatment intervals. Field tests showed that Bs had no residual activity against anopheline larvae. Both microbials provided complete protection when applied weekly. The basic training of personnel in identification of habitats, calibration of application equipment and active larviciding proved to be successful and achieved full coverage and control of mosquito larvae for three months under fully operational conditions. Conclusion Environmentally safe microbial larvicides can significantly reduce larval abundance in the natural habitats of The Gambia and could be a useful tool for inclusion in an IVM programme. The costs of the intervention in this setting could be reduced with formulations that provide a greater residual effect. PMID:17555570

Effects of temperature on survival and development of early life stage Pacific and western brook lampreys

USGS Publications Warehouse

Meeuwig, M.H.; Bayer, J.M.; Seelye, J.G.

2005-01-01

We examined the effects of temperature (10, 14, 18, and 22??C) on survival and development of Pacific lampreys Lampetra tridentata and western brook lampreys L. richardsoni during embryological and early larval stages. The temperature for zero development was estimated for each species, and the response to temperature was measured as the proportion of individuals surviving to hatch, surviving to the larval stage, and exhibiting abnormalities at the larval stage (i.e., malformations of the body). The estimated temperature for zero development was 4.850C for Pacific lampreys and 4.97??C for western brook lampreys. Survival was greatest at 18??C, followed by 14, 10, and 22??C, significant differences being observed between 22??C and the other temperatures. Overall survival was significantly greater for western brook lampreys than for Pacific lampreys; however, the overall difference in proportion of individuals surviving was only 0.02. Overall survival significantly decreased from the time of hatch (proportion surviving = 0.85) to the larval stage (0.82; i.e., during the free-embryo stage). The proportion of individuals exhibiting abnormalities at the larval stage was greatest at 22??C, followed by 18, 10, and 14??C, significant differences being observed between 22??C and the other temperatures. These data provide baseline information on the thermal requirements of early life stage Pacific and western brook lampreys and will aid in assessment and prediction of suitable spawning and rearing habitats for these species.

Efficiency of two larval diets for mass-rearing of the mosquito Aedes aegypti

PubMed Central

Bond, J. G.; Ramírez-Osorio, A.; Marina, C. F.; Fernández-Salas, I.; Liedo, P.; Dor, A.

2017-01-01

Aedes aegypti is a major vector of arboviruses that may be controlled on an area-wide basis using the sterile insect technique (SIT). Larval diet is a major factor in mass-rearing for SIT programs. We compared dietary effects on immature development and adult fitness-related characteristics for an International Atomic Energy Agency (IAEA) diet, developed for rearing Ae. albopictus, and a standardized laboratory rodent diet (LRD), under a 14:10 h (light:dark) photoperiod ("light" treatment) or continuous darkness during larval rearing. Larval development was generally fastest in the IAEA diet, likely reflecting the high protein and lipid content of this diet. The proportion of larvae that survived to pupation or to adult emergence did not differ significantly between diets or light treatments. Insects from the LRD-dark treatment produced the highest proportion of male pupae (93% at 24 h after the beginning of pupation) whereas adult sex ratio from the IAEA diet tended to be more male-biased than that of the LRD diet. Adult longevity did not differ significantly with larval diet or light conditions, irrespective of sex. In other aspects the LRD diet generally performed best. Adult males from the LRD diet were significantly larger than those from the IAEA diet, irrespective of light treatment. Females from the LRD diet had ~25% higher fecundity and ~8% higher egg fertility compared to those from the IAEA diet. Adult flight ability did not differ between larval diets, and males had a similar number of copulations with wild females, irrespective of larval diet. The LRD diet had lower protein and fat content but a higher carbohydrate and energetic content than the IAEA diet. We conclude that the LRD diet is a low-cost standardized diet that is likely to be suitable for mass-rearing of Ae. aegypti for area-wide SIT-based vector control. PMID:29095933

Growing Pains: Development of the Larval Nocifensive Response in Drosophila

PubMed Central

SULKOWSKI, MIKOLAJ J.; KUROSAWA, MATHIEU S.; OX, DANIEL N.

2014-01-01

The ability to perceive and avoid harmful substances or stimuli is key to an organism’s survival. The neuronal cognate of the perception of pain is known as nociception, and the reflexive motion to avoid pain is termed the nocifensive response. As the nocifensive response is an ancient and evolutionarily conserved behavioral response to nociceptive stimuli, it is amenable to study in relatively simple and genetically tractable model systems such as Drosophila. Recent studies have taken advantage of the useful properties of Drosophila larvae to begin elucidating the neuronal connectivity and molecular machinery underlying the nocifensive response. However, these studies have primarily utilized the third-instar larval stage, and many mutations that potentially influence nociception survive only until earlier larval stages. Here we characterize the nocifensive responses of Drosophila throughout larval development and find dramatic changes in the nature of the behavior. Notably, we find that prior to the third instar, larvae are unable to perform the characteristic “corkscrew-like roll” behavior. Also, we identify an avoidance behavior consistent with a nocifensive response that is present immediately after larval hatching, representing a paradigm that may be useful in examining mutations with an early lethal phenotype. PMID:22186918

The development of the tapeworm Diphyllobothrium latum (L. 1756) (Cestoda; Pseudophyllidea) in its definitive hosts, with special references to the growth patterns of D. dendriticum (Nitzsch, 1824) and D. ditremum (Creplin, 1827).

PubMed

Andersen, K

1978-08-01

When Diphyllobothrium latum develops from larva to adult in a definitive host, it first sheds the entire larval 'body' before growth of an adult strobila starts. This process of shedding off the entire larval abothrial extremity, piece by piece, takes about 48 h. By this time the larva has usually reached the anterior third of the small intestine of the host. D. dendriticum and D. ditremum develop quite differently, although exhibiting similar anterior migrations. In these two species the larvae develop directly into adults without the larval 'body' first being shed. The implications of the observed differences in growth pattern between these three species of Diphyllobothrium to the classification of diphyllobothriid cestodes is discussed briefly.

Bioinsecticidal activity of Talisia esculenta reserve protein on growth and serine digestive enzymes during larval development of Anticarsia gemmatalis.

PubMed

Macedo, Maria Lígia R; Freire, Maria das Graças M; Kubo, Carlos Eduardo G; Parra, José Roberto P

2011-01-01

Plants synthesize a variety of molecules to defend themselves against an attack by insects. Talisin is a reserve protein from Talisia esculenta seeds, the first to be characterized from the family Sapindaceae. In this study, the insecticidal activity of Talisin was tested by incorporating the reserve protein into an artificial diet fed to the velvetbean caterpillar Anticarsia gemmatalis, the major pest of soybean crops in Brazil. At 1.5% (w/w) of the dietary protein, Talisin affected larval growth, pupal weight, development and mortality, adult fertility and longevity, and produced malformations in pupae and adult insects. Talisin inhibited the trypsin-like activity of larval midgut homogenates. The trypsin activity in Talisin-fed larvae was sensitive to Talisin, indicating that no novel protease-resistant to Talisin was induced in Talisin-fed larvae. Affinity chromatography showed that Talisin bound to midgut proteinases of the insect A. gemmatalis, but was resistant to enzymatic digestion by these larval proteinases. The transformation of genes coding for this reserve protein could be useful for developing insect resistant crops. Copyright © 2010 Elsevier Inc. All rights reserved.

Temperature effects on gene expression and morphological development of European eel, Anguilla anguilla larvae

PubMed Central

Mazurais, David; Servili, Arianna; Zambonino-Infante, Jose-Luis; Miest, Joanna J.; Sørensen, Sune R.; Tomkiewicz, Jonna; Butts, Ian A. E.

2017-01-01

Temperature is important for optimization of rearing conditions in aquaculture, especially during the critical early life history stages of fish. Here, we experimentally investigated the impact of temperature (16, 18, 20, 22 and 24°C) on thermally induced phenotypic variability, from larval hatch to first-feeding, and the linked expression of targeted genes [heat shock proteins (hsp), growth hormone (gh) and insulin-like growth factors (igf)] associated to larval performance of European eel, Anguilla anguilla. Temperature effects on larval morphology and gene expression were investigated throughout early larval development (in real time from 0 to 18 days post hatch) and at specific developmental stages (hatch, jaw/teeth formation, and first-feeding). Results showed that hatch success, yolk utilization efficiency, survival, deformities, yolk utilization, and growth rates were all significantly affected by temperature. In real time, increasing temperature from 16 to 22°C accelerated larval development, while larval gene expression patterns (hsp70, hsp90, gh and igf-1) were delayed at cold temperatures (16°C) or accelerated at warm temperatures (20–22°C). All targeted genes (hsp70, hsp90, gh, igf-1, igf-2a, igf-2b) were differentially expressed during larval development. Moreover, expression of gh was highest at 16°C during the jaw/teeth formation, and the first-feeding developmental stages, while expression of hsp90 was highest at 22°C, suggesting thermal stress. Furthermore, 24°C was shown to be deleterious (resulting in 100% mortality), while 16°C and 22°C (~50 and 90% deformities respectively) represent the lower and upper thermal tolerance limits. In conclusion, the high survival, lowest incidence of deformities at hatch, high yolk utilization efficiency, high gh and low hsp expression, suggest 18°C as the optimal temperature for offspring of European eel. Furthermore, our results suggest that the still enigmatic early life history stages of European eel may inhabit the deeper layer of the Sargasso Sea and indicate vulnerability of this critically endangered species to increasing ocean temperature. PMID:28806748

Estuarine Larval Development and Upstream Post-Larval Migration of Freshwater Shrimps in Two Tropical Rivers of Puerto Rico

Treesearch

Jonathan P. Benstead; James G. March; Catherine M. Pringle

2000-01-01

Migratory freshwater shrimps represent important links between the headwaters and estuaries of many tropical rivers. These species exhibit amphidromous life cycles in which larvae are released by females in upper reaches of rivers; first stage (i.e., newly hatched) larvae drift passively to coastal environments where they develop and metamorphose into postlarvae...

GROWTH AND VARIATIONS IN LIPID CLASS AND FATTY ACID COMPOSITION DURING LARVAL DEVELOPMENT OF THE STONE CRAB, MENIPPE ADINA WILLIAMS AND FELDER, 1986

EPA Science Inventory

Larval development in decapod crustaceans is marked by variable growth patterns and changes in weight and biochemical composition. Larvae of the stone crab, Menippe adina, were mass-reared under laboratory conditions (28|C; 20o/ooS) from hatching to the megalopal stage. Growth in...

GROWTH AND VARIATIONS IN LIPID CLASS AND FATTY ACID COMPOSITION DURING LARVAL DEVELOPMENT OF THE STONE CRAB, MENIPPE ADINA WILLIAMS AND FELDER, 1986.

EPA Science Inventory

Larval development in decapod crustaceans is marked by variable growth patterns and changes in weight and biochemical composition. Larvae of the stone crab, Menippe adina, were mass-reared under laboratory conditions (28?C; 20o/ooS) from hatching to the megalopa stage. Growth in...

Changes in protein expression during honey bee larval development.

PubMed

Chan, Queenie W T; Foster, Leonard J

2008-10-29

The honey bee (Apis mellifera), besides its role in pollination and honey production, serves as a model for studying the biochemistry of development, metabolism, and immunity in a social organism. Here we use mass spectrometry-based quantitative proteomics to quantify nearly 800 proteins during the 5- to 6-day larval developmental stage, tracking their expression profiles. We report that honey bee larval growth is marked by an age-correlated increase of protein transporters and receptors, as well as protein nutrient stores, while opposite trends in protein translation activity and turnover were observed. Levels of the immunity factors prophenoloxidase and apismin are positively correlated with development, while others surprisingly were not significantly age-regulated, suggesting a molecular explanation for why bees are susceptible to major age-associated bee bacterial infections such as American Foulbrood or fungal diseases such as chalkbrood. Previously unreported findings include the reduction of antioxidant and G proteins in aging larvae. These data have allowed us to integrate disparate findings in previous studies to build a model of metabolism and maturity of the immune system during larval development. This publicly accessible resource for protein expression trends will help generate new hypotheses in the increasingly important field of honey bee research.

Development of DNA-based Identification methods to track the ...

EPA Pesticide Factsheets

The ability to track the identity and abundance of larval fish, which are ubiquitous during spawning season, may lead to a greater understanding of fish species distributions in Great Lakes nearshore areas including early-detection of invasive fish species before they become established. However, larval fish are notoriously hard to identify using traditional morphological techniques. While DNA-based identification methods could increase the ability of aquatic resource managers to determine larval fish composition, use of these methods in aquatic surveys is still uncommon and presents many challenges. In response to this need, we have been working with the U. S. Fish and Wildlife Service to develop field and laboratory methods to facilitate the identification of larval fish using DNA-meta-barcoding. In 2012, we initiated a pilot-project to develop a workflow for conducting DNA-based identification, and compared the species composition at sites within the St. Louis River Estuary of Lake Superior using traditional identification versus DNA meta-barcoding. In 2013, we extended this research to conduct DNA-identification of fish larvae collected from multiple nearshore areas of the Great Lakes by the USFWS. The species composition of larval fish generally mirrored that of fish species known from the same areas, but was influenced by the timing and intensity of sampling. Results indicate that DNA-based identification needs only very low levels of biomass to detect pre

Immature stages of Spodoptera eridania (Lepidoptera: Noctuidae): developmental parameters and host plants.

PubMed

Montezano, Débora Goulart; Specht, Alexandre; Sosa-Gómez, Daniel Ricardo; Roque-Specht, Vânia Ferreira; de Barros, Neiva Monteiro

2014-01-01

This study aimed to detail the temporal and morphological parameters of the immature stages of southern armyworm Spodoptera eridania (Stoll, 1782) with larvae feed on artificial diet, under controlled conditions (25 ± 1°C, 70 ± 10% relative humidity and 14-h photophase) and gather information about their larval host plants. The viability of the egg, larval, pupal, and prepupal stages was 97.82, 93.62, 96.42, and 97.03%, respectively. The average duration of the egg, larval, pupal, and pre-pupal stages was 4.00, 16.18, 1.58, and 9.17 d, respectively. During the larval stage, 43.44% of females passed through seven instars, observing that the female's development was significant slower than males. The female larvae that developed through six and seven instars exhibited a mean growth rate of 1.52 and 1.44, respectively. Female pupae were significantly larger, exhibiting faster development than males. The rearing method proved to be adequate, providing more detailed observations of the biological cycle, especially at the larval stage, and resulting in an overall survival of almost 85%. Two hundred two plant species belonging to 58 families are listed as natural hosts for S. eridania, mainly including Asteraceae, Fabaceae, Solanaceae, Poaceae, Amaranthaceae, and Malvaceae. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

Live prey enrichment, with particular emphasis on HUFAs, as limiting factor in false percula clownfish (Amphiprion ocellaris, Pomacentridae) larval development and metamorphosis: molecular and biochemical implications.

PubMed

Olivotto, Ike; Di Stefano, Michele; Rosetti, Silvestro; Cossignani, Lina; Pugnaloni, Armanda; Giantomassi, Federica; Carnevali, Oliana

2011-07-01

In fast growing organisms, like fish larvae, fatty acids provided through live prey are essential to satisfy high energy demand and are required to promote growth. Therefore, in recent decades, a great amount of research has been directed towards the development of lipid enrichment in order to improve larval fish survival and growth. However, in fish, the biochemical and molecular processes related to highly unsaturated fatty acid (HUFA) administration are still poorly understood. In the current study, the false percula clownfish, a short larval phase marine species, was used as an experimental model and the effects of a standard and a HUFAs-enriched diet were tested through a molecular, biochemical, ultrastructural and morphometric approach. Our results support the hypothesis that HUFA administration may improve larval development through the presence of better structured mitochondria, a higher synthesis of energy compounds and coenzymes with a central position in the metabolism, with respect to controls. This higher energy status was confirmed by better growth performance and a shorter larval phase in larvae fed with an enriched diet with respect to the control. This strategy of rapid growth and early energy storage may be considered positively adaptive and beneficial to the survival of this species. Copyright © 2011 Elsevier Inc. All rights reserved.

The resting sites and blood-meal sources of Anopheles minimus in Taiwan.

PubMed

Chang, Mei-Chun; Teng, Hwa-Jen; Chen, Chen-Fu; Chen, Yung-Chen; Jeng, Chian-Ren

2008-06-09

The WHO declared Taiwan free from malaria in 1965, but in 2003 the reporting of two introduced cases in a rural area suggested a possible local transmission of this disease. Therefore, understanding the resting sites and the blood sources of Anopheles minimus is crucial in order to provide information for implementing vector control strategies. During a two-year survey, mosquitoes were collected in houses and their surrounding areas and at the bank of larval habitats by backpack aspirators in 17 villages in rural areas of southern and eastern Taiwan for 1 hr. On the same day, blacklight traps were hung downward overnight. Blood-fed mosquito samples were analysed by PCR. Of the 195 total households surveyed by backpack aspirators, no Anopheles adults were collected inside the houses, while a single Anopheles minimus and a single Anopheles maculatus were collected outside of the houses. On the same day, 23 An. minimus, two An. maculatus, two Anopheles ludlowae, two Anopheles sinensis, and one Anopheles tessellatus were collected along the bank of larval habitats. In blacklight traps hung outside of the houses in the villages, 69 An. minimus, 62 An. ludlowae, 31 An. sinensis, and 19 An. maculatus were collected. In larval habitats, 98 An. ludlowae, 64 An. minimus, 49 An. sinensis, and 14 An. maculatus were collected. Of a total of 10 blood-fed samples, An. minimus fed on four animals including bovine (60%), dogs (20%), pig (10%), and non-chicken avian (10%). Anopheles minimus, an opportunist feeder in Taiwan, was not collected inside the houses, but was found outside of the houses in villages and surrounding larval habitats. Therefore, an outdoor transmission of malaria is likely to occur and, thus, the bed nets, which are favoured for controlling the late biting of An. minimus, should be a very efficient and effective method for those local residents who sleep outdoors. Additionally, space spray of insecticides for Anopheles at night, as well as residual spray inside animal huts and selective larval habitats, are also helpful to control female adults.

The resting sites and blood-meal sources of Anopheles minimus in Taiwan

PubMed Central

Chang, Mei-Chun; Teng, Hwa-Jen; Chen, Chen-Fu; Chen, Yung-Chen; Jeng, Chian-Ren

2008-01-01

Background The WHO declared Taiwan free from malaria in 1965, but in 2003 the reporting of two introduced cases in a rural area suggested a possible local transmission of this disease. Therefore, understanding the resting sites and the blood sources of Anopheles minimus is crucial in order to provide information for implementing vector control strategies. Methods During a two-year survey, mosquitoes were collected in houses and their surrounding areas and at the bank of larval habitats by backpack aspirators in 17 villages in rural areas of southern and eastern Taiwan for 1 hr. On the same day, blacklight traps were hung downward overnight. Blood-fed mosquito samples were analysed by PCR. Results Of the 195 total households surveyed by backpack aspirators, no Anopheles adults were collected inside the houses, while a single Anopheles minimus and a single Anopheles maculatus were collected outside of the houses. On the same day, 23 An. minimus, two An. maculatus, two Anopheles ludlowae, two Anopheles sinensis, and one Anopheles tessellatus were collected along the bank of larval habitats. In blacklight traps hung outside of the houses in the villages, 69 An. minimus, 62 An. ludlowae, 31 An. sinensis, and 19 An. maculatus were collected. In larval habitats, 98 An. ludlowae, 64 An. minimus, 49 An. sinensis, and 14 An. maculatus were collected. Of a total of 10 blood-fed samples, An. minimus fed on four animals including bovine (60%), dogs (20%), pig (10%), and non-chicken avian (10%). Conclusion Anopheles minimus, an opportunist feeder in Taiwan, was not collected inside the houses, but was found outside of the houses in villages and surrounding larval habitats. Therefore, an outdoor transmission of malaria is likely to occur and, thus, the bed nets, which are favoured for controlling the late biting of An. minimus, should be a very efficient and effective method for those local residents who sleep outdoors. Additionally, space spray of insecticides for Anopheles at night, as well as residual spray inside animal huts and selective larval habitats, are also helpful to control female adults. PMID:18538036

Temporal changes in the bacterial community of animal feces and their correlation with stable fly oviposition, larval development, and adult fitness

PubMed Central

Albuquerque, Thais A.; Zurek, Ludek

2014-01-01

Stable flies are blood-feeding insects with a great negative impact on animals world wide. Larvae develop primarily in animal manure and bacteria are essential for larval development; however, the principle of this dependence is not understood. We hypothesized that as the microbial community of animal manure changes over time, it plays an important role in stable fly fitness. Two-choice bioassays were conducted using 2 week old horse manure (control) and aging horse manure (fresh to 5 week old) to evaluate the effect of manure age on stable fly oviposition. Our data showed that fresh feces did not stimulate oviposition and that the attractiveness increased as manure aged but started to decline after 3 weeks. Bioassays assessing the effect of manure age at the time of oviposition on larval development demonstrated that 1–3 week old manure supported larval development significantly better than fresh, 4, and 5 week old manure. In addition, adult fitness (body size) was significantly higher in flies from 1 and 2 week old manure comparing to that of all other treatments. Analysis of the bacterial community of aging horse manure by 454-pyrosequencing of 16S rDNA revealed a great reduction in bacterial diversity and richness from fresh to 1–5 week old manure and a major shift from strict anaerobes in fresh manure to facultative anaerobes and strict aerobes in aged manure. Overall, the microbial community of 2 and 3 week old horse manure with its dominant bacterial taxa Rhizobium, Devosia, and Brevundimonas stimulated stable fly oviposition the most and provided a suitable habitat for larval development. These bacteria represent the candidates for studies focused on better understanding of stable fly – microbial interactions. PMID:25426108

Rearing and Maintaining Midge Cultures (Chironomus tentans) for Laboratory Studies.

ERIC Educational Resources Information Center

Hein, John; Mahadeva, Madhu N.

1992-01-01

The life history of the Chironomus tentans can be observed in easily established and maintained laboratory cultures. Projects for the classroom include observing hydration of an egg mass; embryonic development, hatching and larval feeding; larval activity; and mating activity. (MDH)

Specific inhibition of Xenorhabdus hominickii, an entomopathogenic bacterium, against different types of host insect phospholipase A2.

PubMed

Sadekuzzaman, Md; Kim, Yonggyun

2017-10-01

Phospholipase A 2 (PLA 2 ) hydrolyzes ester bond of phospholipids at the sn-2 position to release free fatty acid and lysophospholipids. Some PLA 2 s preferentially release arachidonic acid which is subsequently oxygenated into eicosanoids to mediate immune responses in insects. Xenorhabdus hominickii is an entomopathogenic bacterium that can suppress insect immunity by inhibiting PLA 2 activity. However, little is known about target PLA 2 types inhibited by X. hominickii. Therefore, the objective of this study was to determine PLA 2 types in the host insect, Spodoptera exigua using specific inhibitors. All developmental stages of S. exigua possessed significant PLA 2 activities, with late larval stages showing relatively higher PLA 2 activities. In different larval tissues, hemocytes had higher PLA 2 activities than fat body, gut, or epidermis. Various developmental and tissue extracts exhibited differential susceptibilities to three different PLA 2 inhibitors. Late larva-to-adult stages were highly susceptible to all three different types of PLA 2 inhibitors. In contrast, extracts from egg and young larval stages were not susceptible to secretory PLA 2 (sPLA 2 ) or calcium-independent cellular PLA 2 (iPLA 2 ) inhibitors, although they were susceptible to a calcium-dependent cellular PLA 2 (cPLA 2 ) inhibitor in a dose-dependent manner. Different tissues of fifth instars exhibited variation in susceptibility to inhibitors, with epidermal tissue being sensitive to cPLA 2 inhibitor only while other tissues were sensitive to all three types of inhibitors. Bacterial challenge with heat-killed X. hominickii significantly increased PLA 2 activity. However, live bacteria suppressed the induction of PLA 2 activity. An organic extract of X. hominickii-culture broth inhibited the susceptibility of S. exigua to sPLA 2 - and iPLA 2 - specific inhibitors, but not to cPLA 2 -specific inhibitor. Oxindole, a component of the organic extract, exhibited an inhibitory pattern similar to the organic extract. Taken together, our results indicate that S. exigua possesses different PLA 2 types and that X. hominickii can inhibit PLA 2 s susceptible to sPLA 2 - and iPLA 2 - specific inhibitors. Copyright © 2017 Elsevier Inc. All rights reserved.

C. elegans GATA factors EGL-18 and ELT-6 function downstream of Wnt signaling to maintain the progenitor fate during larval asymmetric divisions of the seam cells.

PubMed

Gorrepati, Lakshmi; Thompson, Kenneth W; Eisenmann, David M

2013-05-01

The C. elegans seam cells are lateral epithelial cells arrayed in a single line from anterior to posterior that divide in an asymmetric, stem cell-like manner during larval development. These asymmetric divisions are regulated by Wnt signaling; in most divisions, the posterior daughter in which the Wnt pathway is activated maintains the progenitor seam fate, while the anterior daughter in which the Wnt pathway is not activated adopts a differentiated hypodermal fate. Using mRNA tagging and microarray analysis, we identified the functionally redundant GATA factor genes egl-18 and elt-6 as Wnt pathway targets in the larval seam cells. EGL-18 and ELT-6 have previously been shown to be required for initial seam cell specification in the embryo. We show that in larval seam cell asymmetric divisions, EGL-18 is expressed strongly in the posterior seam-fated daughter. egl-18 and elt-6 are necessary for larval seam cell specification, and for hypodermal to seam cell fate transformations induced by ectopic Wnt pathway overactivation. The TCF homolog POP-1 binds a site in the egl-18 promoter in vitro, and this site is necessary for robust seam cell expression in vivo. Finally, larval overexpression of EGL-18 is sufficient to drive expression of a seam marker in other hypodermal cells in wild-type animals, and in anterior hypodermal-fated daughters in a Wnt pathway-sensitized background. These data suggest that two GATA factors that are required for seam cell specification in the embryo independently of Wnt signaling are reused downstream of Wnt signaling to maintain the progenitor fate during stem cell-like divisions in larval development.

C. elegans GATA factors EGL-18 and ELT-6 function downstream of Wnt signaling to maintain the progenitor fate during larval asymmetric divisions of the seam cells

PubMed Central

Gorrepati, Lakshmi; Thompson, Kenneth W.; Eisenmann, David M.

2013-01-01

The C. elegans seam cells are lateral epithelial cells arrayed in a single line from anterior to posterior that divide in an asymmetric, stem cell-like manner during larval development. These asymmetric divisions are regulated by Wnt signaling; in most divisions, the posterior daughter in which the Wnt pathway is activated maintains the progenitor seam fate, while the anterior daughter in which the Wnt pathway is not activated adopts a differentiated hypodermal fate. Using mRNA tagging and microarray analysis, we identified the functionally redundant GATA factor genes egl-18 and elt-6 as Wnt pathway targets in the larval seam cells. EGL-18 and ELT-6 have previously been shown to be required for initial seam cell specification in the embryo. We show that in larval seam cell asymmetric divisions, EGL-18 is expressed strongly in the posterior seam-fated daughter. egl-18 and elt-6 are necessary for larval seam cell specification, and for hypodermal to seam cell fate transformations induced by ectopic Wnt pathway overactivation. The TCF homolog POP-1 binds a site in the egl-18 promoter in vitro, and this site is necessary for robust seam cell expression in vivo. Finally, larval overexpression of EGL-18 is sufficient to drive expression of a seam marker in other hypodermal cells in wild-type animals, and in anterior hypodermal-fated daughters in a Wnt pathway-sensitized background. These data suggest that two GATA factors that are required for seam cell specification in the embryo independently of Wnt signaling are reused downstream of Wnt signaling to maintain the progenitor fate during stem cell-like divisions in larval development. PMID:23633508

Temperature during larval development and adult maintenance influences the survival of Anopheles gambiae s.s.

PubMed

Christiansen-Jucht, Céline; Parham, Paul E; Saddler, Adam; Koella, Jacob C; Basáñez, María-Gloria

2014-11-05

Malaria transmission depends on vector life-history parameters and population dynamics, and particularly on the survival of adult Anopheles mosquitoes. These dynamics are sensitive to climatic and environmental factors, and temperature is a particularly important driver. Data currently exist on the influence of constant and fluctuating adult environmental temperature on adult Anopheles gambiae s.s. survival and on the effect of larval environmental temperature on larval survival, but none on how larval temperature affects adult life-history parameters. Mosquito larvae and pupae were reared individually at different temperatures (23 ± 1°C, 27 ± 1°C, 31 ± 1°C, and 35 ± 1°C), 75 ± 5% relative humidity. Upon emergence into imagoes, individual adult females were either left at their larval temperature or placed at a different temperature within the range above. Survival was monitored every 24 hours and data were analysed using non-parametric and parametric methods. The Gompertz distribution fitted the survivorship data better than the gamma, Weibull, and exponential distributions overall and was adopted to describe mosquito mortality rates. Increasing environmental temperature during the larval stages decreased larval survival (p < 0.001). Increases of 4°C (from 23°C to 27°C, 27°C to 31°C, and 31°C to 35°C), 8°C (27°C to 35°C) and 12°C (23°C to 35°C) statistically significantly increased larval mortality (p < 0.001). Higher environmental temperature during the adult stages significantly lowered adult survival overall (p < 0.001), with increases of 4°C and 8°C significantly influencing survival (p < 0.001). Increasing the larval environment temperature also significantly increased adult mortality overall (p < 0.001): a 4°C increase (23°C to 27°C) did not significantly affect adult survival (p > 0.05), but an 8°C increase did (p < 0.05). The effect of a 4°C increase in larval temperature from 27°C to 31°C depended on the adult environmental temperature. The data also suggest that differences between the temperatures of the larval and adult environments affects adult mosquito survival. Environmental temperature affects Anopheles survival directly during the juvenile and adult stages, and indirectly, since temperature during larval development significantly influences adult survival. These results will help to parameterise more reliable mathematical models investigating the potential impact of temperature and global warming on malaria transmission.

Independent and interactive effects of immune activation and larval diet on adult immune function, growth and development in the greater wax moth (Galleria mellonella).

PubMed

Kangassalo, Katariina; Valtonen, Terhi M; Sorvari, Jouni; Kecko, Sanita; Pölkki, Mari; Krams, Indrikis; Krama, Tatjana; Rantala, Markus J

2018-06-29

Organisms in the wild are likely to face multiple immune challenges as well as additional ecological stressors, yet their interactive effects on immune function are poorly understood. Insects are found to respond to cues of increased infection risk by enhancing their immune capacity. However, such adaptive plasticity in immune function may be limited by physiological and environmental constraints. Here, we investigated the effects of two environmental stressors - poor larval diet and an artificial parasite-like immune challenge at the pupal stage - on adult immune function, growth and development in the greater wax moth (Galleria mellonella). Males whose immune system was activated with an artificial parasite-like immune challenge had weaker immune response - measured as strength of encapsulation response - as adults compared to the control groups, but only when raised in high-nutrition larval diet. Immune activation did not negatively affect adult immune response in males reared in low-nutrition larval diet, indicating that poor larval diet improved the capacity of the insects to respond to repeated immune challenges. Low-nutrition larval diet also had a positive independent effect on immune capacity in females, yet it negatively affected development time and adult body mass in both sexes. As in the nature immune challenges are rarely isolated, and adverse nutritional environment may indicate an elevated risk of infection, resilience to repeated immune challenges as a response to poor nutritional environment could provide a significant fitness advantage. The present study highlights the importance of considering environmental context when investigating effects of immune activation in insects. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Effects of fish cues on mosquito larvae development.

PubMed

Silberbush, Alon; Abramsky, Zvika; Tsurim, Ido

2015-10-01

We investigated the effects of predator-released kairomones on life history traits of larval Culex pipiens (Linnaeus). We compared the development time and survival of sibling larvae, reared in either water conditioned by the presence of Gambusia affinis (Baird and Girard) or fishless control-water. Our results indicate that larvae developing in fish-conditioned water (FCW) pupated faster than larvae in fishless-control water. The effect of FCW on larval survival was evident only in females. Surprisingly, FCW increased female survival. In both development-time and survival, boiling the water eliminated the FCW effect, supporting our hypothesis that fish conditioning is based on kairomones. Accelerated metamorphosis in response to predator released kairomones, evident in our results, is a rarely described phenomenon. Intuitively, when exposed to predator associated signals, aquatic larvae should metamorphose earlier to escape the higher risk of predation. However, theoretical models predict this outcome only under specific conditions. Indeed, longer - rather than shorter - time to metamorphosis is usually observed in response to predation risk. We argue that the response of larval mosquitoes to predation risk is context-dependent. Shortening larval development time may not be an exceptional response, but rather represents a part of a response spectrum that depends on the level of predation risk and resource abundance. Copyright © 2015 Elsevier B.V. All rights reserved.

Detection of in situ protein-protein complexes at the Drosophila larval neuromuscular junction using proximity ligation assay.

PubMed

Wang, Simon; Yoo, SooHyun; Kim, Hae-Yoon; Wang, Mannan; Zheng, Clare; Parkhouse, Wade; Krieger, Charles; Harden, Nicholas

2015-01-20

Discs large (Dlg) is a conserved member of the membrane-associated guanylate kinase family, and serves as a major scaffolding protein at the larval neuromuscular junction (NMJ) in Drosophila. Previous studies have shown that the postsynaptic distribution of Dlg at the larval NMJ overlaps with that of Hu-li tai shao (Hts), a homologue to the mammalian adducins. In addition, Dlg and Hts are observed to form a complex with each other based on co-immunoprecipitation experiments involving whole adult fly lysates. Due to the nature of these experiments, however, it was unknown whether this complex exists specifically at the NMJ during larval development. Proximity Ligation Assay (PLA) is a recently developed technique used mostly in cell and tissue culture that can detect protein-protein interactions in situ. In this assay, samples are incubated with primary antibodies against the two proteins of interest using standard immunohistochemical procedures. The primary antibodies are then detected with a specially designed pair of oligonucleotide-conjugated secondary antibodies, termed PLA probes, which can be used to generate a signal only when the two probes have bound in close proximity to each other. Thus, proteins that are in a complex can be visualized. Here, it is demonstrated how PLA can be used to detect in situ protein-protein interactions at the Drosophila larval NMJ. The technique is performed on larval body wall muscle preparations to show that a complex between Dlg and Hts does indeed exist at the postsynaptic region of NMJs.

Characteristics of the larval Echinococcus vogeli Rausch and Bernstein, 1972 in the natural intermediate host, the paca, Cuniculus paca L. (Rodentia: Dasyproctidae).

PubMed

Rausch, R L; D'Alessandro, A; Rausch, V R

1981-09-01

In Colombia, the natural intermediate host of Echinococcus vogeli Rausch and Bernstein, 1972 is the paca, Cuniculus paca L. (Rodentia: Dasyproctidae). The larval cestode develops in the liver of the host, where it usually is situated superficially, partly exposed beneath Glisson's capsule. The infective larva consists of a subspherical to asymmetrical, fluid-filled vesicle, up to 30 mm in diameter, enclosed by a thick laminated membrane. It typically contains numerous chambers, often interconnected, produced by endogenous proliferation of germinal and laminated tissue, within which brood capsules arise in an irregular pattern from the germinal layer. Invasive growth by means of exogenous proliferation, typical of infections in man, was not observed in the natural intermediate host. The development of the larval cestode is described on the basis of material from pacas, supplemented by observations on early-stage lesions in experimentally infected nutrias, Myocastor coypus (Molina) (Rodentia: Capromyidae). The tissue response is characterized for early-stage, mature (infective), and degenerating larvae in the comparatively long-lived intermediate host. In addition to previously reported differences in size and form of rostellar hooks, other morphologic characteristics are defined by which the larval stage of E. vogeli is distinguished from that of E. oligarthrus (Diesing, 1863). Pathogenesis by the larval E. vogeli in man, like that by the larval E. multilocularis Leuckart, 1863, is the consequence of atypical proliferation of vesicles attributable to parasite-host incompatibility.

Mutation of a cuticular protein, BmorCPR2, alters larval body shape and adaptability in silkworm, Bombyx mori.

PubMed

Qiao, Liang; Xiong, Gao; Wang, Ri-xin; He, Song-zhen; Chen, Jie; Tong, Xiao-ling; Hu, Hai; Li, Chun-lin; Gai, Ting-ting; Xin, Ya-qun; Liu, Xiao-fan; Chen, Bin; Xiang, Zhong-huai; Lu, Cheng; Dai, Fang-yin

2014-04-01

Cuticular proteins (CPs) are crucial components of the insect cuticle. Although numerous genes encoding cuticular proteins have been identified in known insect genomes to date, their functions in maintaining insect body shape and adaptability remain largely unknown. In the current study, positional cloning led to the identification of a gene encoding an RR1-type cuticular protein, BmorCPR2, highly expressed in larval chitin-rich tissues and at the mulberry leaf-eating stages, which is responsible for the silkworm stony mutant. In the Dazao-stony strain, the BmorCPR2 allele is a deletion mutation with significantly lower expression, compared to the wild-type Dazao strain. Dysfunctional BmorCPR2 in the stony mutant lost chitin binding ability, leading to reduced chitin content in larval cuticle, limitation of cuticle extension, abatement of cuticle tensile properties, and aberrant ratio between internodes and intersegmental folds. These variations induce a significant decrease in cuticle capacity to hold the growing internal organs in the larval development process, resulting in whole-body stiffness, tightness, and hardness, bulging intersegmental folds, and serious defects in larval adaptability. To our knowledge, this is the first study to report the corresponding phenotype of stony in insects caused by mutation of RR1-type cuticular protein. Our findings collectively shed light on the specific role of cuticular proteins in maintaining normal larval body shape and will aid in the development of pest control strategies for the management of Lepidoptera.

Digestion in sea urchin larvae impaired under ocean acidification

NASA Astrophysics Data System (ADS)

Stumpp, Meike; Hu, Marian; Casties, Isabel; Saborowski, Reinhard; Bleich, Markus; Melzner, Frank; Dupont, Sam

2013-12-01

Larval stages are considered as the weakest link when a species is exposed to challenging environmental changes. Reduced rates of growth and development in larval stages of calcifying invertebrates in response to ocean acidification might be caused by energetic limitations. So far no information exists on how ocean acidification affects digestive processes in marine larval stages. Here we reveal alkaline (~pH 9.5) conditions in the stomach of sea urchin larvae. Larvae exposed to decreased seawater pH suffer from a drop in gastric pH, which directly translates into decreased digestive efficiencies and triggers compensatory feeding. These results suggest that larval digestion represents a critical process in the context of ocean acidification, which has been overlooked so far.

The safety of 17a-methyltestosterone administered in feed to larval Nile tilapia

USDA-ARS?s Scientific Manuscript database

Techniques developed to control sexual differentiation in fishes have typically involved androgen or estrogen (i.e., steroid) treatment, which directs sexual differentiation toward males or females. Treatment regimens have included immersion of larval fish in water containing a steroid, incorporati...

Functional Assays and Alternative Species: Using Larval Zebrafish in Developmental Neurotoxicity Screening

EPA Science Inventory

The U.S. Environmental Protection Agency is developing and evaluating methods to screen and prioritize large numbers of chemicals for developmental toxicity. Towards this goal, we are exploring methods to detect developmental neurotoxicants in very young larval zebrafish. We have...

Diet and density dependent competition affect larval performance and oviposition site selection in the mosquito species Aedes albopictus (Diptera: Culicidae)

PubMed Central

2012-01-01

Background Oviposition-site choice is an essential component of the life history of all mosquito species. According to the oviposition-preference offspring-performance (P-P) hypothesis, if optimizing offspring performance and fitness ensures high overall reproductive fitness for a given species, the female should accurately assess details of the heterogeneous environment and lay her eggs preferentially in sites with conditions more suitable to offspring. Methods We empirically tested the P-P hypothesis using the mosquito species Aedes albopictus by artificially manipulating two habitat conditions: diet (measured as mg of food added to a container) and conspecific density (CD; number of pre-existing larvae of the same species). Immature development (larval mortality, development time to pupation and time to emergence) and fitness (measured as wing length) were monitored from first instar through adult emergence using a factorial experimental design over two ascending gradients of diet (2.0, 3.6, 7.2 and 20 mg food/300 ml water) and CD (0, 20, 40 and 80 larvae/300 ml water). Treatments that exerted the most contrasting values of larval performance were recreated in a second experiment consisting of single-female oviposition site selection assay. Results Development time decreased as food concentration increased, except from 7.2 mg to 20.0 mg (Two-Way CR ANOVA Post-Hoc test, P > 0.1). Development time decreased also as conspecific density increased from zero to 80 larvae (Two-Way CR ANOVA Post-Hoc test, P < 0.5). Combined, these results support the role of density-dependent competition for resources as a limiting factor for mosquito larval performance. Oviposition assays indicated that female mosquitoes select for larval habitats with conspecifics and that larval density was more important than diet in driving selection for oviposition sites. Conclusions This study supports predictions of the P-P hypothesis and provides a mechanistic understanding of the underlying factors driving mosquito oviposition site selection. PMID:23044004

Immunolocalization and expression of Na(+)/K(+) -ATPase in embryos, early larval stages and adults of the freshwater shrimp Palaemonetes argentinus (Decapoda, Caridea, Palaemonidae).

PubMed

Ituarte, Romina Belén; Lignot, Jehan-Hervé; Charmantier, Guy; Spivak, Eduardo; Lorin-Nebel, Catherine

2016-06-01

The euryhaline shrimp Palaemonetes argentinus exemplifies an evolutionary transition from brackish to freshwater habitats that requires adequate osmoregulatory capacities. Hyperosmoregulation is functional at hatching and it likely begins during the embryonic phase allowing this species to develop entirely in fresh water. Here, we investigated the Na(+)/K(+)-ATPase α-subunit gene (nka-α) expression using quantitative real-time PCR and localized Na(+)/K(+)-ATPase (NKA) in ion-transporting epithelia through immunofluorescence microscopy. We reared shrimps from spawning to juvenile stages at two salinities (1, 15 ‰) and maintained adults for 3 weeks at three salinity treatments (1, 15, 25 ‰). nka-α gene expression was measured in: (1) embryos at an early (SI), intermediate (SII) and late (SIII) stage of embryonic development; (2) newly hatched larvae (Zoea I, ZI); and (3) isolated gill tissue of adults. The nka-α expression was low in SI and SII embryos and reached maximum levels prior to hatching (SIII), which were similar to expression levels detected in the ZI. The nka-α expression in SIII and ZI was highest at 15 ‰, whereas salinity did not affect expression in earlier embryos. In SIII, in ZI and in a later zoeal stage ZIV, NKA was localized in epithelial cells of pleurae, in the inner-side epithelium of branchiostegite and in the antennal glands. Gills appeared in the ZIV but NKA immunolabeling of the cells of the gill shaft occurred in a subsequent developmental larval stage, the decapodid. Extrabranchial organs constitute the main site of osmoregulation in early ontogenetic stages of this freshwater shrimp.

Potential effects of physiological plastic responses to salinity on population networks of the estuarine crab Chasmagnathus granulata

NASA Astrophysics Data System (ADS)

Giménez, Luis

2002-12-01

Chasmagnathus granulata is a South American crab occurring in estuarine salt marshes of the Brazilian, Uruguayan and Argentine coasts. Life history is characterized by an export strategy of its larval stages. I reviewed information on experimental manipulation of salinity during embryonic and larval development (pre- and posthatching salinities), and on habitat characteristics of C. granulata in order to determine potential effects of larval response to salinity in the field and to suggest consequences for the population structure. Local populations are spread over coastal areas with different physical characteristics. Benthic phases occupy estuaries characterized by different patterns of salinity variation, and release larvae to coastal waters characterized by strong salinity gradients. The zoea 1 of C. granulata showed a strong acclimatory response to low salinity. This response operated only during the first weeks of development (during zoeae 1 and 2) since subsequent larval survival at low posthatching salinities was consistently low. Larvae developing at low salinity frequently followed a developmental pathway with five instead of four zoeal stages. The ability to acclimate and the variability in larval development (i.e. the existence of alternative developmental pathways) could be interpreted as a strategy to buffer environmental variability at spatial scales of local or population networks. Early survivorship and production of larvae may be relatively high across a rather wide range of variability in salinity (5-32‰). Plastic responses to low salinity would therefore contribute to maintain a certain degree of population connectivity and persistence regardless of habitat heterogeneity.

Potential effects of physiological plastic responses to salinity on population networks of the estuarine crab Chasmagnathus granulata

NASA Astrophysics Data System (ADS)

Giménez, Luis

2003-01-01

Chasmagnathus granulata is a South American crab occurring in estuarine salt marshes of the Brazilian, Uruguayan and Argentine coasts. Life history is characterized by an export strategy of its larval stages. I reviewed information on experimental manipulation of salinity during embryonic and larval development (pre- and posthatching salinities), and on habitat characteristics of C. granulata in order to determine potential effects of larval response to salinity in the field and to suggest consequences for the population structure. Local populations are spread over coastal areas with different physical characteristics. Benthic phases occupy estuaries characterized by different patterns of salinity variation, and release larvae to coastal waters characterized by strong salinity gradients. The zoea 1 of C. granulata showed a strong acclimatory response to low salinity. This response operated only during the first weeks of development (during zoeae 1 and 2) since subsequent larval survival at low posthatching salinities was consistently low. Larvae developing at low salinity frequently followed a developmental pathway with five instead of four zoeal stages. The ability to acclimate and the variability in larval development (i.e. the existence of alternative developmental pathways) could be interpreted as a strategy to buffer environmental variability at spatial scales of local or population networks. Early survivorship and production of larvae may be relatively high across a rather wide range of variability in salinity (5-32‰). Plastic responses to low salinity would therefore contribute to maintain a certain degree of population connectivity and persistence regardless of habitat heterogeneity.

The effect of purified condensed tannins of forage plants from Botswana on the free-living stages of gastrointestinal nematode parasites of livestock.

PubMed

Tibe, O; Sutherland, I A; Lesperance, L; Harding, D R K

2013-10-18

The effect of condensed tannins (CT) extracted from forage plants from Botswana on the free-living stages of a number of species of gastrointestinal nematode parasites derived from infected sheep were investigated using in vitro assays. Fresh samples of five different plants (Viscum rotundifolium, Viscum verrucosum, Tapinanthus oleifolius, Grewia flava and Ipomoea sinensis) were collected over two summers (February 2009 and 2010). Fractionation of each crude extract on a Sephadex LH-20 column yielded low molecular weight phenolics and CT-containing fractions. The effect of each purified CT fraction on parasites was evaluated using either egg hatch, larval development or larval migration inhibition assays. Three gastrointestinal nematode species (Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta) derived from infected sheep were evaluated in the study. CT from V. rotundifolium and I. sinensis fractions from samples collected in 2009 and 2010 did not inhibit larval development. However, CT isolated from V. verrucosum, T. oleifolius and G. flava collected in 2009 completely inhibited the development of all parasite species. These CT fractions were more potent in inhibiting larval development of H. contortus than fractions from the same plant species collected in 2010. However, a slight effect on larval migration was observed with some CT extracts. The results suggest that CT extracts of some forage plants from Botswana have anti-parasitic properties in vitro, and that further research is required to determine any in vivo efficacy from feeding the plants to goats in a field situation. Copyright © 2013 Elsevier B.V. All rights reserved.

An integrated analysis of phenotypic selection on insect body size and development time.

PubMed

Eck, Daniel J; Shaw, Ruth G; Geyer, Charles J; Kingsolver, Joel G

2015-09-01

Most studies of phenotypic selection do not estimate selection or fitness surfaces for multiple components of fitness within a unified statistical framework. This makes it difficult or impossible to assess how selection operates on traits through variation in multiple components of fitness. We describe a new generation of aster models that can evaluate phenotypic selection by accounting for timing of life-history transitions and their effect on population growth rate, in addition to survival and reproductive output. We use this approach to estimate selection on body size and development time for a field population of the herbivorous insect, Manduca sexta (Lepidoptera: Sphingidae). Estimated fitness surfaces revealed strong and significant directional selection favoring both larger adult size (via effects on egg counts) and more rapid rates of early larval development (via effects on larval survival). Incorporating the timing of reproduction and its influence on population growth rate into the analysis resulted in larger values for size in early larval development at which fitness is maximized, and weaker selection on size in early larval development. These results illustrate how the interplay of different components of fitness can influence selection on size and development time. This integrated modeling framework can be readily applied to studies of phenotypic selection via multiple fitness components in other systems. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

The transcriptomic and evolutionary signature of social interactions regulating honey bee caste development.

PubMed

Vojvodic, Svjetlana; Johnson, Brian R; Harpur, Brock A; Kent, Clement F; Zayed, Amro; Anderson, Kirk E; Linksvayer, Timothy A

2015-11-01

The caste fate of developing female honey bee larvae is strictly socially regulated by adult nurse workers. As a result of this social regulation, nurse-expressed genes as well as larval-expressed genes may affect caste expression and evolution. We used a novel transcriptomic approach to identify genes with putative direct and indirect effects on honey bee caste development, and we subsequently studied the relative rates of molecular evolution at these caste-associated genes. We experimentally induced the production of new queens by removing the current colony queen, and we used RNA sequencing to study the gene expression profiles of both developing larvae and their caregiving nurses before and after queen removal. By comparing the gene expression profiles of queen-destined versus worker-destined larvae as well as nurses observed feeding these two types of larvae, we identified larval and nurse genes associated with caste development. Of 950 differentially expressed genes associated with caste, 82% were expressed in larvae with putative direct effects on larval caste, and 18% were expressed in nurses with putative indirect effects on caste. Estimated selection coefficients suggest that both nurse and larval genes putatively associated with caste are rapidly evolving, especially those genes associated with worker development. Altogether, our results suggest that indirect effect genes play important roles in both the expression and evolution of socially influenced traits such as caste.

New biomarkers of post-settlement growth in the sea urchin Strongylocentrotus purpuratus.

PubMed

Fadl, Alyaa Elsaid Abdelaziz; Mahfouz, Magdy Elsayed; El-Gamal, Mona Mabrouk Taha; Heyland, Andreas

2017-10-01

Some sea urchins, including the purple sea urchin Strongylocentrotus purpuratus, have been successfully used in aquaculture, but their slow growth and late reproduction are challenging to overcome when developing efficient aquaculture production techniques. S. purpuratus develops via an indirect life history that is characterized by a drastic settlement process at the end of a larval period that lasts for several weeks. During this transition, the bilateral larva is transformed into a pentaradial juvenile, which will start feeding and growing in the benthic habitat. Due to predation and other ecological factors, settlement is typically associated with high mortality rates in juvenile populations. Additionally, juveniles require several days to develop a functional mouth and digestive system. During this perimetamorphic period, juveniles use up larval resources until they are capable to digest adult food. Mechanisms underlying the onset of juvenile feeding and metabolism have implications for the recruitment of natural populations as well as aquaculture and are relatively poorly understood in S. purpuratus . The insulin/insulin-like growth factor signalling (IIS)/Target of Rapamycin (TOR) pathway (IIS/TOR) is well conserved among animal phyla and regulates physiological and developmental functions, such as growth, reproduction, aging and nutritional status. We analyzed the expression of FoxO, TOR, and ILPs in post-settlement juveniles in conjunction with their early growth trajectories. We also tested how pre-settlement starvation affected post-settlement expression of IIS. We found that FoxO provides a useful molecular marker in early juveniles as its expression is strongly correlated with juvenile growth. We also found that pre-settlement starvation affects juvenile growth trajectories as well as IIS. Our findings provide preliminary insights into the mechanisms underlying post-settlement growth and metabolism in S. purpuratus . They also have important implications for sea urchin aquaculture, as they show that pre-settlement nutrient environment significantly affects both early growth trajectories and gene expression. This information can be used to develop new biomarkers for juvenile health in sea urchin population ecology and aquaculture aquaculture.

Exposure to 2,4-decadienal negatively impacts upon marine invertebrate larval fitness.

PubMed

Caldwell, Gary S; Lewis, Ceri; Olive, Peter J W; Bentley, Matthew G

2005-06-01

Diatoms liberate volatile, biologically active unsaturated aldehydes following cell damage, which negatively impact upon invertebrate reproductive processes such as fertilization, embryogenesis and larval survival. 2,4-Decadienal is frequently identified among the aldehydes produced and is one of the more biologically active. The majority of studies which have examined the toxic effects of diatom aldehydes to invertebrate reproduction have scored egg production and/or hatching success as indicators of biological impacts. There are very few studies which have dealt specifically with the impacts of diatom-derived aldehydes on larval fitness. Larval stages of the polychaetes Arenicola marina and Nereis virens and the echinoderms Asterias rubens and Psammechinus miliaris exposed to 2,4-decadienal at sub 1 microg ml(-1) concentrations suffered reduced survival over the incubation period (day 1-8 post fertilization) with detectable differences for the polychates at a concentration of 0.005 and 0.01-0.1 microg ml(-1) for the echinoderms. Susceptibility of larval N. virens was investigated using stage specific 24 h exposures at 2,4-decadienal concentrations up to 1.5 microg ml(-1). A clear stage specific effect was found, with earlier larval stages most vulnerable. Nectochaete larvae (9-10 d) showed no reduction in survival at the concentrations assayed. Fluctuating asymmetry (FA), defined as random deviations from perfect bilateral symmetry, was used to analyse fitness of larval P. miliaris exposed to 2,4-decadienal at concentrations of 0.1, 0.5 and 1 microg ml(-1). The degree and frequency of asymmetrical development increased with increasing 2,4-decadienal concentration. Equally, as FA increased larval survival decreased. These results provide further support for the teratogenic nature of 2,4-decadienal and its negative impact on invertebrate larval fitness.

Morphology-flow interactions lead to stage-selective vertical transport of larval sand dollars in shear flow.

PubMed

Clay, T W; Grünbaum, D

2010-04-01

Many larvae and other plankton have complex and variable morphologies of unknown functional significance. We experimentally and theoretically investigated the functional consequences of the complex morphologies of larval sand dollars, Dendraster excentricus (Eschscholtz), for hydrodynamic interactions between swimming and turbulent water motion. Vertical shearing flows (horizontal gradients of vertical flow) tilt organisms with simple geometries (e.g. spheres, ellipsoids), causing these organisms to move horizontally towards downwelling water and compromising their abilities to swim upwards. A biomechanical model of corresponding hydrodynamic interactions between turbulence-induced shear and the morphologically complex four-, six- and eight-armed stages of sand dollar larvae suggests that the movements of larval morphologies differ quantitatively and qualitatively across stages and shear intensities: at shear levels typical of calm conditions in estuarine and coastal environments, all modeled larval stages moved upward. However, at higher shears, modeled four- and eight-armed larvae moved towards downwelling, whereas six-armed larvae moved towards upwelling. We also experimentally quantified larval movement by tracking larvae swimming in low-intensity shear while simultaneously mapping the surrounding flow fields. Four- and eight-armed larvae moved into downwelling water, but six-armed larvae did not. Both the model and experiments suggest that stage-dependent changes to larval morphology lead to differences in larval movement: four- and eight-armed stages are more prone than the six-armed stage to moving into downwelling water. Our results suggest a mechanism by which differences can arise in the vertical distribution among larval stages. The ability to mitigate or exploit hydrodynamic interactions with shear is a functional consequence that potentially shapes larval evolution and development.

Effects of larvicidal and larval nutritional stresses on Anopheles gambiae development, survival and competence for Plasmodium falciparum.

PubMed

Vantaux, Amélie; Ouattarra, Issiaka; Lefèvre, Thierry; Dabiré, Kounbobr Roch

2016-04-23

Many studies have shown that the environment in which larvae develop can influence adult characteristics with consequences for the transmission of pathogens. We investigated how two environmental stresses (larviciding and nutritional stress) interact to affect Anopheles gambiae (previously An. gambiae S molecular form) life history traits and its susceptibility for field isolates of its natural malaria agent Plasmodium falciparum. Larvae were reared in the presence or not of a sub-lethal concentration of larvicide and under a high and low food regimen. Development time, individual size, adult survival and competence for P. falciparum were assessed. Individuals under low food regimen took more time to develop, had a lower development success and were smaller while there was no main effect of larvicide exposure on these traits. However, larvicide exposure impacted individual size in interaction with nutritional stress. Female survival was affected by the interaction between gametocytemia, parasite exposure and larval diet, as well as the interaction between gametocytemia, parasite exposure and larvicidal stress, and the interaction between gametocytemia, larvicidal exposure and larval diet. Among the 951 females dissected 7 days post-infection, 559 (58.78%) harboured parasites. Parasite prevalence was significantly affected by the interaction between larvicidal stress and larval diet. Indeed, females under low food regimen had a higher prevalence than females under high food regimen and this difference was greater under larvicidal stress. The two stresses did not impact parasite intensity. We found that larval nutritional and larvicidal stresses affect mosquito life history traits in complex ways, which could greatly affect P. falciparum transmission. Further studies combining field-based trials on larvicide use and mosquito experimental infections would give a more accurate understanding of the effects of this vector control tool on malaria transmission.

Reproduction and development in Halocaridina rubra Holthuis, 1963 (Crustacea: Atyidae) clarifies larval ecology in the Hawaiian anchialine ecosystem.

PubMed

Havird, Justin C; Vaught, Rebecca C; Weese, David A; Santos, Scott R

2015-10-01

Larvae in aquatic habitats often develop in environments different from those they inhabit as adults. Shrimp in the Atyidae exemplify this trend, as larvae of many species require salt or brackish water for development, while adults are freshwater-adapted. An exception within the Atyidae family is the "anchialine clade," which are euryhaline as adults and endemic to habitats with subterranean fresh and marine water influences. Although the Hawaiian anchialine atyid Halocaridina rubra is a strong osmoregulator, its larvae have never been observed in nature. Moreover, larval development in anchialine species is poorly studied. Here, reproductive trends in laboratory colonies over a 5-y period are presented from seven genetic lineages and one mixed population of H. rubra; larval survivorship under varying salinities is also discussed. The presence and number of larvae differed significantly among lineages, with the mixed population being the most prolific. Statistical differences in reproduction attributable to seasonality also were identified. Larval survivorship was lowest (12% settlement rate) at a salinity approaching fresh water and significantly higher in brackish and seawater (88% and 72%, respectively). Correlated with this finding, identifiable gills capable of ion transport did not develop until metamorphosis into juveniles. Thus, early life stages of H. rubra are apparently excluded from surface waters, which are characterized by lower and fluctuating salinities. Instead, these stages are restricted to the subterranean (where there is higher and more stable salinity) portion of Hawaii's anchialine habitats due to their inability to tolerate low salinities. Taken together, these data contribute to the understudied area of larval ecology in the anchialine ecosystem. © 2015 Marine Biological Laboratory.

Linking ocean acidification and warming to the larval development of the American lobster (Homarus americanus)

NASA Astrophysics Data System (ADS)

Waller, J. D.; Fields, D.; Wahle, R.; Mcveigh, H.; Greenwood, S.

2016-02-01

The American lobster upholds the most culturally and economically iconic fishery in New England. Over the past three decades lobster landings have risen steadily in northern New England as lobster populations have shifted northward, leaving policy makers and coastal communities wondering what the future of this fishery may hold. The underlying causes of this population shift are likely due to a suite of environmental stressors including increasing temperature and ocean acidification. In this study we investigated the interactive effects of IPCC predicted temperature and pH on key aspects of larval lobster development (size, survival, development time, respiration rate, swimming speed, prey consumption and gene expression). Our experiments showed that larvae raised in the high temperature treatments (19 °C) experienced significantly higher mortality than larvae in our control treatments (16 °C) with 50% mortality occurring in the high temperature treatment one week after hatching. The larvae in these high temperature treatments developed twice as fast and experienced respiration rates that were three times higher in the third and fourth larval stages. While temperature had a distinct effect, pH treatment had few significant effects on any of our measured parameters. These data suggest that projected end-century warming will have greater adverse effects than acidification on early larval survival, despite the hurrying effect of higher temperatures on lobster larval development and increase in physiological activity. There were no significant treatment effects on carapace length, dry weight, or carbon and nitrogen content. Analysis of swimming speed and gene expression (through RNA sequencing) are in progress. Understanding how the most vulnerable life stages of the lobster life cycle responds to climate change is essential in connecting the northward geographic shifts projected by habitat quality models, and the underlying physiological and genetic mechanisms that drive their ecology.

Distributions of larval and juvenile/adult stages of the Antarctic myctophid fish, Electrona antarctica, off Wilkes Land in East Antarctica

NASA Astrophysics Data System (ADS)

Moteki, Masato; Fujii, Kentaro; Amakasu, Kazuo; Shimada, Keishi; Tanimura, Atsushi; Odate, Tsuneo

2017-06-01

Myctophid fish are an important component of the Southern Ocean food web because of their very high biomass. This study investigated the spatial distributions of larval and juvenile/adult stages of the Antarctic myctophid Electrona antarctica. Fish were sampled in January 2011 and 2012 on a transect along 140°E and in January 2013 along 110°E using two different opening/closing net systems. In total, 1075 specimens of E. antarctica were collected: 948 larvae, 127 juveniles/adults, and 2 in the transformation stage. Most larvae were collected at 5-200 m depth, with diel vertical migration (DVM) not apparent. Larvae were mainly distributed in the Modified Circumpolar Deep Water (-1.5 °C-2.0 °C). By contrast, an analysis of the echogram at 38 kHz and discrete depth samples implied that juveniles/adults undertook DVM except in the continental slope area (65.5°S). As the distribution of krill is limited to the cold water mass (<-1.5 °C) along the continental slope, E. antarctica and krill populations are spatially separated off Wilkes Land during summer. According to the previously estimated larval period of 30-47 days, E. antarctica may spawn in late November to December in the marginal ice zone or near the sea ice edge. This study suggests that the environment related to sea ice provides a nursery ground for early stage larvae of E. antarctica.

Implications of a temperature increase for host plant range: predictions for a butterfly

PubMed Central

Audusseau, Hélène; Nylin, Sören; Janz, Niklas

2013-01-01

Although changes in phenology and species associations are relatively well-documented responses to global warming, the potential interactions between these phenomena are less well understood. In this study, we investigate the interactions between temperature, phenology (in terms of seasonal timing of larval growth) and host plant use in the polyphagous butterfly Polygonia c-album. We found that the hierarchy of larval performance on three natural host plants was not modified by a temperature increase as such. However, larval performance on each host plant and temperature treatment was affected by rearing season. Even though larvae performed better at the higher temperature regardless of the time of the rearing, relative differences between host plants changed with the season. For larvae reared late in the season, performance was always better on the herbaceous plant than on the woody plants. In this species, it is likely that a prolonged warming will lead to a shift from univoltinism to bivoltinism. The demonstrated interaction between host plant suitability and season means that such a shift is likely to lead to a shift in selective regime, favoring specialization on the herbaceous host. Based on our result, we suggest that host range evolution in response to temperature increase would in this species be highly contingent on whether the population undergoes a predicted shift from one to two generations. We discuss the effect of global warming on species associations and the outcome of asynchrony in rates of phenological change. PMID:24101991

Comparative larval growth and mortality of mesopelagic fishes and their predatory impact on zooplankton in the Kuroshio region

NASA Astrophysics Data System (ADS)

Sassa, Chiyuki; Takahashi, Motomitsu

2018-01-01

Larvae of mesopelagic fishes usually dominate in oceanic larval fish assemblages, but detailed investigations of their ecology are limited and thus preclude full assessment of the ecosystem structure and dynamics in oceanic waters. Here, we examined the growth and mortality of six taxa of numerically dominant mesopelagic fish larvae and their predatory impact on zooplankton in the Kuroshio region off southern Japan during late winter. The weight-specific growth coefficient (Gw) ranged from 0.077 (Sigmops gracilis) to 0.156 d-1 (Vinciguerria nimbaria), and the instantaneous daily mortality coefficient (M) from 0.067 (S. gracilis) to 0.143 d-1 (Myctophum asperum). The ratio Gw/M, an index of stage-specific survival of the larvae, was from 0.90 (Notoscopelus japonicus) to 1.24 (V. nimbaria), without a significant difference from a value of 1 in all species. Based on the reported relationship between Gw and ingestion rate of the larval fishes, the daily ration of each species was calculated to be 32-57% of body dry weight d-1. Mean and 95% confidence interval of food requirements of the six taxa of larvae was 1.41 ± 0.55 mg C m-2 d-1. Predatory impact of the mesopelagic fish larvae on the production rate of the available prey was estimated to be approximately 3.5-5.2%, implying that the larvae have a low level but consistent effect on zooplankton production in the oligotrophic Kuroshio region.

Environmental factors limiting fertilisation and larval success in corals

NASA Astrophysics Data System (ADS)

Woods, Rachael M.; Baird, Andrew H.; Mizerek, Toni L.; Madin, Joshua S.

2016-12-01

Events in the early life history of reef-building corals, including fertilisation and larval survival, are susceptible to changes in the chemical and physical properties of sea water. Quantifying how changes in water quality affect these events is therefore important for understanding and predicting population establishment in novel and changing environments. A review of the literature identified that levels of salinity, temperature, pH, suspended sediment, nutrients and heavy metals affect coral early life-history stages to various degrees. In this study, we combined published experimental data to determine the relative importance of sea water properties for coral fertilisation success and larval survivorship. Of the water properties manipulated in experiments, fertilisation success was most sensitive to suspended sediment, copper, salinity, phosphate and ammonium. Larval survivorship was sensitive to copper, lead and salinity. A combined model was developed that estimated the joint probability of both fertilisation and larval survivorship in sea water with different chemical and physical properties. We demonstrated the combined model using water samples from Sydney and Lizard Island in Australia to estimate the likelihood of larvae surviving through both stages of development to settlement competency. Our combined model could be used to recommend targets for water quality in coastal waterways as well as to predict the potential for species to expand their geographical ranges in response to climate change.

Effect of Oxadiazolyl 3(2H)-Pyridazinone on the Larval Growth and Digestive Physiology of the Armyworm, Pseudaletia separata

PubMed Central

Huang, Qingchun; Kong, Yuping; Liu, Manhui; Feng, Jun; Liu, Yang

2008-01-01

The effect of oxadiazolyl 3(2H)-pyridazinone (ODP), a new insect growth regulator, on growth of larvae of the armyworm, Pseudaletia separata Walker (Lepidoptera: Noctuidae) was evaluated in comparison to the insecticide, toosendanin, a tetranortriterpenoid extracted from the bark of Melia toosendan that has multiple effects on insects. The digestive physiological properties of these compounds on insects were investigated by feeding them maize leaves dipped in these compounds. The results showed that ODP inhibited the growth of P. separata significantly, causing a slowed development and a prolonged larval period, smaller body size and sluggish behavior, delayed pupation and a reduced eclosion rate of pupae and adults. Moreover, ODP strongly inhibited the activities of weak alkaline trypsine-like enzyme, chymotrypsin-like enzyme and alpha amylase in the midguts of fifth instar P. separata larvae, in vivo, and inhibited the activity of alpha amylase, in vitro. These data suggest that ODP has severe consequences on the larval carbohydrate assimilation and/or nutrient intake and thereby causes inhibition of larval growth. The regulatory action of ODP on larval growth development was similar to that of toosendanin; both could be used to decrease the growth of insect populations. PMID:20337556

Investigating phenology of larval fishes in St. Louis River ...

EPA Pesticide Factsheets

As part of the development of an early detection monitoring strategy for non-native fishes, larval fish surveys have been conducted since 2012 in the St. Louis River estuary. Survey data demonstrates there is considerable variability in fish abundance and species assemblages across different habitats and at multiple temporal scales. To optimize early detection monitoring we need to understand temporal and spatial patterns of larval fishes related to their development and dispersion, as well as the environmental factors that influence them. In 2016 we designed an experiment to assess the phenological variability in larval fish abundance and assemblages amongst shallow water habitats. Specifically, we sought to contrast different thermal environments and turbidity levels, as well as assess the importance of vegetation in these habitats. To evaluate phenological differences we sampled larval fish bi-weekly at nine locations from mid-May to mid-July. Sampling locations were split between upper estuary and lower estuary to contrast river versus seiche influenced habitats. To assess differences in thermal environments, temperature was monitored every 15 minutes at each sampling location throughout the study, beginning in early April. Our design also included sampling at both vegetated (or pre-vegetated) and non-vegetated stations within each sampling location throughout the study to assess the importance of this habitat variable. Hydroacoustic surveys (Biosonics) were

A Carboniferous insect gall: insight into early ecologic history of the Holometabola.

PubMed Central

Labandeira, C C; Phillips, T L

1996-01-01

Although the prevalence or even occurrence of insect herbivory during the Late Carboniferous (Pennsylvanian) has been questioned, we present the earliest-known ecologic evidence showing that by Late Pennsylvanian times (302 million years ago) a larva of the Holometabola was galling the internal tissue of Psaronius tree-fern fronds. Several diagnostic cellular and histological features of these petiole galls have been preserved in exquisite detail, including an excavated axial lumen filled with fecal pellets and comminuted frass, plant-produced response tissue surrounding the lumen, and specificity by the larval herbivore for a particular host species and tissue type. Whereas most suggestions over-whelmingly support the evolution of such intimate and reciprocal plant-insect interactions 175 million years later, we provide documentation that before the demise of Pennsylvanian age coal-swamp forests, a highly stereotyped life cycle was already established between an insect that was consuming internal plant tissue and a vascular plant host responding to that herbivory. This and related discoveries of insect herbivore consumption of Psaronius tissues indicate that modern-style herbivores were established in Late Pennsylvanian coal-swamp forests. Images Fig. 1 PMID:11607697

Crucial roles of Pox neuro in the developing ellipsoid body and antennal lobes of the Drosophila brain

PubMed Central

Minocha, Shilpi; Boll, Werner

2017-01-01

The paired box gene Pox neuro (Poxn) is expressed in two bilaterally symmetric neuronal clusters of the developing adult Drosophila brain, a protocerebral dorsal cluster (DC) and a deutocerebral ventral cluster (VC). We show that all cells that express Poxn in the developing brain are postmitotic neurons. During embryogenesis, the DC and VC consist of only 20 and 12 neurons that express Poxn, designated embryonic Poxn-neurons. The number of Poxn-neurons increases only during the third larval instar, when the DC and VC increase dramatically to about 242 and 109 Poxn-neurons, respectively, virtually all of which survive to the adult stage, while no new Poxn-neurons are added during metamorphosis. Although the vast majority of Poxn-neurons express Poxn only during third instar, about half of them are born by the end of embryogenesis, as demonstrated by the absence of BrdU incorporation during larval stages. At late third instar, embryonic Poxn-neurons, which begin to express Poxn during embryogenesis, can be easily distinguished from embryonic-born and larval-born Poxn-neurons, which begin to express Poxn only during third instar, (i) by the absence of Pros, (ii) their overt differentiation of axons and neurites, and (iii) the strikingly larger diameter of their cell bodies still apparent in the adult brain. The embryonic Poxn-neurons are primary neurons that lay out the pioneering tracts for the secondary Poxn-neurons, which differentiate projections and axons that follow those of the primary neurons during metamorphosis. The DC and the VC participate only in two neuropils of the adult brain. The DC forms most, if not all, of the neurons that connect the bulb (lateral triangle) with the ellipsoid body, a prominent neuropil of the central complex, while the VC forms most of the ventral projection neurons of the antennal lobe, which connect it ipsilaterally to the lateral horn, bypassing the mushroom bodies. In addition, Poxn-neurons of the VC are ventral local interneurons of the antennal lobe. In the absence of Poxn protein in the developing brain, embryonic Poxn-neurons stall their projections and cannot find their proper target neuropils, the bulb and ellipsoid body in the case of the DC, or the antennal lobe and lateral horn in the case of the VC, whereby the absence of the ellipsoid body neuropil is particularly striking. Poxn is thus crucial for pathfinding both in the DC and VC. Additional implications of our results are discussed. PMID:28441464

The Biology and Ecology of the Emerald Ash Borer, Agrilus planipennis, in China

PubMed Central

Wang, Xiao-Yi; Yang, Zhong-Qi; Gould, Juli R.; Zhang, Yi-Nan; Liu, Gui-Jun; Liu, EnShan

2010-01-01

The biology, ecology, and life cycle of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), were studied using regular inspection in the forest and observations in the laboratory. Results indicated that A. planipennis are mostly univoltine in Tianjin, China. They overwintered individually as mature larvae in shallow chambers excavated in the outer sapwood. In late July, some full-grown larvae began to build overwintering chambers, and all larvae entered the sapwood for dormancy by early November. A. planipennis pupated in the overwintering chamber from early April to mid May the following year, and the average pupal duration was about 20 days. In late April, some newly eclosed adults could be found in the pupal cells, but they had not yet emerged from the tree. Adults began to emerge in early May, with peak flight occurring in mid May. The average longevity of adults was about 21 days and the adult stage lasted through early July. The adults fed on ash foliage as a source of nutrition. Mating was usually conducted and completed on the leaf or trunk surfaces of ash trees. Oviposition began in mid May and eggs hatched on average in 15.7 days. The first instar larvae appeared in early June. The larval stage lasted about 300 days to complete an entire generation. The emerald ash borer had four larval instars on velvet ash, Fraxinus velutina (Scrophulariales: Oleaceae). The major natural control factors of A. planipennis were also investigated, and preliminary suggestions for its integrated management are proposed. PMID:20879922

The biology and ecology of the emerald ash borer, Agrilus planipennis, in China.

PubMed

Wang, Xiao-Yi; Yang, Zhong-Qi; Gould, Juli R; Zhang, Yi-Nan; Liu, Gui-Jun; Liu, En-shan

2010-01-01

The biology, ecology, and life cycle of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), were studied using regular inspection in the forest and observations in the laboratory. Results indicated that A. planipennis are mostly univoltine in Tianjin, China. They overwintered individually as mature larvae in shallow chambers excavated in the outer sapwood. In late July, some full-grown larvae began to build overwintering chambers, and all larvae entered the sapwood for dormancy by early November. A. planipennis pupated in the overwintering chamber from early April to mid May the following year, and the average pupal duration was about 20 days. In late April, some newly eclosed adults could be found in the pupal cells, but they had not yet emerged from the tree. Adults began to emerge in early May, with peak flight occurring in mid May. The average longevity of adults was about 21 days and the adult stage lasted through early July. The adults fed on ash foliage as a source of nutrition. Mating was usually conducted and completed on the leaf or trunk surfaces of ash trees. Oviposition began in mid May and eggs hatched on average in 15.7 days. The first instar larvae appeared in early June. The larval stage lasted about 300 days to complete an entire generation. The emerald ash borer had four larval instars on velvet ash, Fraxinus velutina (Scrophulariales: Oleaceae). The major natural control factors of A. planipennis were also investigated, and preliminary suggestions for its integrated management are proposed.

A review of postfeeding larval dispersal in blowflies: implications for forensic entomology

NASA Astrophysics Data System (ADS)

Gomes, Leonardo; Godoy, Wesley Augusto Conde; von Zuben, Claudio José

2006-05-01

Immature and adult stages of blowflies are one of the primary invertebrate consumers of decomposing animal organic matter. When the food supply is consumed or when the larvae complete their development and migrate prior to the total removal of the larval substrate, they disperse to find adequate places for pupation, a process known as postfeeding larval dispersal. Several important ecological and physiological aspects of this process were studied since the work by Green (Ann Appl Biol 38:475, 1951) 50 years ago. An understanding of postfeeding larval dispersal can be useful for determining the postmortem interval (PMI) of human cadavers in legal medicine, particularly because this interval may be underestimated if older dispersing larvae or those that disperse longer, faster, and deeper are not taken into account. In this article, we review the process of postfeeding larval dispersal and its implications for legal medicine, in particular showing that aspects such as burial behavior and competition among species of blowflies can influence this process and consequently, the estimation of PMI.

Evolved differences in larval social behavior mediated by novel pheromones

PubMed Central

Mast, Joshua D; De Moraes, Consuelo M; Alborn, Hans T; Lavis, Luke D; Stern, David L

2014-01-01

Pheromones, chemical signals that convey social information, mediate many insect social behaviors, including navigation and aggregation. Several studies have suggested that behavior during the immature larval stages of Drosophila development is influenced by pheromones, but none of these compounds or the pheromone-receptor neurons that sense them have been identified. Here we report a larval pheromone-signaling pathway. We found that larvae produce two novel long-chain fatty acids that are attractive to other larvae. We identified a single larval chemosensory neuron that detects these molecules. Two members of the pickpocket family of DEG/ENaC channel subunits (ppk23 and ppk29) are required to respond to these pheromones. This pheromone system is evolving quickly, since the larval exudates of D. simulans, the sister species of D. melanogaster, are not attractive to other larvae. Our results define a new pheromone signaling system in Drosophila that shares characteristics with pheromone systems in a wide diversity of insects. DOI: http://dx.doi.org/10.7554/eLife.04205.001 PMID:25497433

The toxicity of a lipid transfer protein (Cc-LTP1) from Coffea canephora Seeds on the larval development of Callosobruchus maculatus (Coleoptera: Bruchidae).

PubMed

Zottich, Umberto; Da Cunha, Maura; Dias, Germana B; Rabelo, Guilherme R; Oliveira, Antonia Elenir A; Carvalho, André O; Fernandes, Kátia Valevski S; do Nascimento, Viviane V; Gomes, Valdirene M

2014-10-01

In this work, we analyzed the effects of coffee seed proteins, especially Cc-LTP1 on the larval development of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae), a bruchid pest of beans and the most important insect pest of Vigna unguiculata (L.) Walp. Artificial seed assay, which incorporated the F/0-90 fraction from Coffea canephora seeds, resulted in the reduction of oviposition and caused an inhibition of C. maculatus larval development in a dose-dependent manner. The F/0-90 fraction used at a 4 % concentration resulted in the survival of no larvae. The purified Cc-LTP1, at a concentration of 0.5 %, also demonstrated effective inhibition of larval development, reducing both females oviposition and the weight and number of larvae. Cc-LTP1 was also able to inhibit the C. maculatus gut α-amylase activity, and immunolabeling by an anti-LTP serum was observed in the midgut tissues of the C. maculatus larvae. Cc-LTP1 has shown binding affinity towards microvillar cells, endoplasmic reticulum and mitochondria, as demonstrated by micrographic images taken by a transmission electron microscope. The results from this study indicate that Cc-LTP1 has insecticidal actions toward C. maculatus and exerts anti-nutritional effects with direct actions on intestinal tissues.

[Effects of temperature on the embryonic development and larval growth of Sepia lycidas].

PubMed

Jiang, Xia-Min; Peng, Rui-Bing; Luo, Jiang; Tang, Feng

2013-05-01

A single-factor experiment was conducted to study the effects of different temperature (15, 18, 21, 24, 27, 30, and 33 degrees C) on the embryonic development and larval growth of Sepia lycidas, aimed to search for the optimum temperature for the development and growth of S. lycidas. The results showed that temperature had significant effects on the embryonic development and larval growth of S. lycidas (P < 0.05). The suitable temperature for hatching ranged from 21 degrees C to 30 degrees C, and the optimum temperature was 24 degrees C. At the optimum temperature, the hatching rate was (93.3 +/- 2.9)%, incubation period was (24.33 +/- 0.58) d, hatching period was (6.00 +/- 1.00) d, completely absorked rate of yolk sac was (96.4 +/- 3.1)%, and newly hatched larvae mass was (0.258 +/- 0.007) g. The effective accumulated temperature model was N = 284.42/(T-12.57). The suitable temperature for the larval survival and growth ranged from 21 degrees C to 30 degrees C, and the optimum temperature was from 24 degrees C to 27 degrees C. At the optimum temperature, the survival rate ranged from 70.0% to 73.3%, and the specific growth rate was from 2.4% to 3.8%.

Investigating phenology of larval fishes in St. Louis River estuary shallow water habitats

EPA Science Inventory

As part of the development of an early detection monitoring strategy for non-native fishes, larval fish surveys have been conducted since 2012 in the St. Louis River estuary. Survey data demonstrates there is considerable variability in fish abundance and species assemblages acro...

Variation in gypsy moth, with comparisons to other Lymantria spp.

Treesearch

Paul W. Schaefer

1991-01-01

Specimens of gypsy moth, Lymantria dispar (L.) sensu lato were displayed in museum trays. Many specimens were quarantine laboratory reared during the 1989 season to provide samples (wing venation, frozen adults, prepupal haemolymph, larval feeding behavior, egg mass hair color, head capsule coloration and larval development) for...

Short report: cysticercosis in an Egyptian mummy of the late Ptolemaic period.

PubMed

Bruschi, Fabrizio; Masetti, Massimo; Locci, Maria Teresa; Ciranni, Rosalba; Fornaciari, Gino

2006-04-01

We describe here an ancient case of cysticercosis that was discovered in an Egyptian mummy of a young woman of about 20 years of age who lived in the late Ptolemaic period (second to first centuries b.c.). On removal of the stomach and its rehydration, a cystic lesion in the stomach wall was observed by naked eye. Microscopical examination of sections of this lesion revealed a cystic structure, with a wall, with numerous projecting eversions, a characteristic feature of the larval stage (cysticercus) of the human tapeworm Taenia solium (or "pig tapeworm"). Immunohistochemical testing with serum from a T. solium-infected human confirmed the identity of the cyst. This finding is the oldest on record of the antiquity of this zoonotic parasite. This observation also confirms that, in Hellenistic Egypt, the farming of swine, along with man an intermediate host of this parasite, was present, and supports other archeological evidence.

rigor mortis encodes a novel nuclear receptor interacting protein required for ecdysone signaling during Drosophila larval development.

PubMed

Gates, Julie; Lam, Geanette; Ortiz, José A; Losson, Régine; Thummel, Carl S

2004-01-01

Pulses of the steroid hormone ecdysone trigger the major developmental transitions in Drosophila, including molting and puparium formation. The ecdysone signal is transduced by the EcR/USP nuclear receptor heterodimer that binds to specific response elements in the genome and directly regulates target gene transcription. We describe a novel nuclear receptor interacting protein encoded by rigor mortis (rig) that is required for ecdysone responses during larval development. rig mutants display defects in molting, delayed larval development, larval lethality, duplicated mouth parts, and defects in puparium formation--phenotypes that resemble those seen in EcR, usp, E75A and betaFTZ-F1 mutants. Although the expression of these nuclear receptor genes is essentially normal in rig mutant larvae, the ecdysone-triggered switch in E74 isoform expression is defective. rig encodes a protein with multiple WD-40 repeats and an LXXLL motif, sequences that act as specific protein-protein interaction domains. Consistent with the presence of these elements and the lethal phenotypes of rig mutants, Rig protein interacts with several Drosophila nuclear receptors in GST pull-down experiments, including EcR, USP, DHR3, SVP and betaFTZ-F1. The ligand binding domain of betaFTZ-F1 is sufficient for this interaction, which can occur in an AF-2-independent manner. Antibody stains reveal that Rig protein is present in the brain and imaginal discs of second and third instar larvae, where it is restricted to the cytoplasm. In larval salivary gland and midgut cells, however, Rig shuttles between the cytoplasm and nucleus in a spatially and temporally regulated manner, at times that correlate with the major lethal phase of rig mutants and major switches in ecdysone-regulated gene expression. Taken together, these data indicate that rig exerts essential functions during larval development through gene-specific effects on ecdysone-regulated transcription, most likely as a cofactor for one or more nuclear receptors. Furthermore, the dynamic intracellular redistribution of Rig protein suggests that it may act to refine spatial and temporal responses to ecdysone during development.

Plant microRNAs in larval food regulate honeybee caste development

PubMed Central

Zhou, Zhen; Kong, Yan; Liang, Hongwei; Lin, Zheguang; Luo, Jun; Zheng, Huoqing; Wan, Ping; Zhang, Junfeng; Zen, Ke; Chen, Jiong; Hu, Fuliang; Zhang, Chen-Yu; Ren, Jie

2017-01-01

The major environmental determinants of honeybee caste development come from larval nutrients: royal jelly stimulates the differentiation of larvae into queens, whereas beebread leads to worker bee fate. However, these determinants are not fully characterized. Here we report that plant RNAs, particularly miRNAs, which are more enriched in beebread than in royal jelly, delay development and decrease body and ovary size in honeybees, thereby preventing larval differentiation into queens and inducing development into worker bees. Mechanistic studies reveal that amTOR, a stimulatory gene in caste differentiation, is the direct target of miR162a. Interestingly, the same effect also exists in non-social Drosophila. When such plant RNAs and miRNAs are fed to Drosophila larvae, they cause extended developmental times and reductions in body weight and length, ovary size and fecundity. This study identifies an uncharacterized function of plant miRNAs that fine-tunes honeybee caste development, offering hints for understanding cross-kingdom interaction and co-evolution. PMID:28859085

Plant microRNAs in larval food regulate honeybee caste development.

PubMed

Zhu, Kegan; Liu, Minghui; Fu, Zheng; Zhou, Zhen; Kong, Yan; Liang, Hongwei; Lin, Zheguang; Luo, Jun; Zheng, Huoqing; Wan, Ping; Zhang, Junfeng; Zen, Ke; Chen, Jiong; Hu, Fuliang; Zhang, Chen-Yu; Ren, Jie; Chen, Xi

2017-08-01

The major environmental determinants of honeybee caste development come from larval nutrients: royal jelly stimulates the differentiation of larvae into queens, whereas beebread leads to worker bee fate. However, these determinants are not fully characterized. Here we report that plant RNAs, particularly miRNAs, which are more enriched in beebread than in royal jelly, delay development and decrease body and ovary size in honeybees, thereby preventing larval differentiation into queens and inducing development into worker bees. Mechanistic studies reveal that amTOR, a stimulatory gene in caste differentiation, is the direct target of miR162a. Interestingly, the same effect also exists in non-social Drosophila. When such plant RNAs and miRNAs are fed to Drosophila larvae, they cause extended developmental times and reductions in body weight and length, ovary size and fecundity. This study identifies an uncharacterized function of plant miRNAs that fine-tunes honeybee caste development, offering hints for understanding cross-kingdom interaction and co-evolution.

Adapted to change: The rapid development of symbiosis in newly settled, fast-maturing chemosymbiotic mussels in the deep sea.

PubMed

Laming, Sven R; Duperron, Sébastien; Gaudron, Sylvie M; Hilário, Ana; Cunha, Marina R

2015-12-01

Symbioses between microbiota and marine metazoa occur globally at chemosynthetic habitats facing imminent threat from anthropogenic disturbance, yet little is known concerning the role of symbiosis during early development in chemosymbiotic metazoans: a critical period in any benthic species' lifecycle. The emerging symbiosis of Idas (sensu lato) simpsoni mussels undergoing development is assessed over a post-larval-to-adult size spectrum using histology and fluorescence in situ hybridisation (FISH). Post-larval development shows similarities to that of both heterotrophic and chemosymbiotic mussels. Data from newly settled specimens confirm aposymbiotic, planktotrophic larval development. Sulphur-oxidising (SOX) symbionts subsequently colonise multiple exposed, non-ciliated epithelia shortly after metamorphosis, but only become abundant on gills as these expand with greater host size. This wide-spread bathymodiolin recorded from sulphidic wood, bone and cold-seep habitats, displays a suite of adaptive traits that could buffer against anthropogenic disturbance. Copyright © 2015 Elsevier Ltd. All rights reserved.

Relevant microclimate for determining the development rate of malaria mosquitoes and possible implications of climate change.

PubMed

Paaijmans, Krijn P; Imbahale, Susan S; Thomas, Matthew B; Takken, Willem

2010-07-09

The relationship between mosquito development and temperature is one of the keys to understanding the current and future dynamics and distribution of vector-borne diseases such as malaria. Many process-based models use mean air temperature to estimate larval development times, and hence adult vector densities and/or malaria risk. Water temperatures in three different-sized water pools, as well as the adjacent air temperature in lowland and highland sites in western Kenya were monitored. Both air and water temperatures were fed into a widely-applied temperature-dependent development model for Anopheles gambiae immatures, and subsequently their impact on predicted vector abundance was assessed. Mean water temperature in typical mosquito breeding sites was 4-6 degrees C higher than the mean temperature of the adjacent air, resulting in larval development rates, and hence population growth rates, that are much higher than predicted based on air temperature. On the other hand, due to the non-linearities in the relationship between temperature and larval development rate, together with a marginal buffering in the increase in water temperature compared with air temperature, the relative increases in larval development rates predicted due to climate change are substantially less. Existing models will tend to underestimate mosquito population growth under current conditions, and may overestimate relative increases in population growth under future climate change. These results highlight the need for better integration of biological and environmental information at the scale relevant to mosquito biology.

A SoxC gene related to larval shell development and co-expression analysis of different shell formation genes in early larvae of oyster.

PubMed

Liu, Gang; Huan, Pin; Liu, Baozhong

2017-06-01

Among the potential larval shell formation genes in mollusks, most are expressed in cells surrounding the shell field during the early phase of shell formation. The only exception (cgi-tyr1) is expressed in the whole larval mantle and thus represents a novel type of expression pattern. This study reports another gene with such an expression pattern. The gene encoded a SoxC homolog of the Pacific oyster Crassostrea gigas and was named cgi-soxc. Whole-mount in situ hybridization revealed that the gene was highly expressed in the whole larval mantle of early larvae. Based on its spatiotemporal expression, cgi-soxc is hypothesized to be involved in periostracum biogenesis, biomineralization, and regulation of cell proliferation. Furthermore, we investigated the interrelationship between cgi-soxc expression and two additional potential shell formation genes, cgi-tyr1 and cgi-gata2/3. The results confirmed co-expression of the three genes in the larval mantle of early D-veliger. Nevertheless, cgi-gata2/3 was only expressed in the mantle edge, and the other two genes were expressed in all mantle cells. Based on the spatial expression patterns of the three genes, two cell groups were identified from the larval mantle (tyr1 + /soxc + /gata2/3 + cells and tyr1 + /soxc + /gata2/3 - cells) and are important to study the differentiation and function of this tissue. The results of this study enrich our knowledge on the structure and function of larval mantle and provide important information to understand the molecular mechanisms of larval shell formation.

Fisheries Closed Areas Strengthen Scallop Larval Settlement and Connectivity Among Closed Areas and Across International Open Fishing Grounds: A Model Study.

PubMed

Davies, Kimberley T A; Gentleman, W C; DiBacco, C; Johnson, C L

2015-09-01

This study examined whether a measured increase in average body size of adult sea scallops inside three fishery closed areas on Georges Bank (GB), United States (US), was sufficient to increase larval supply to closed areas and open fishing areas in both US and Canadian areas of the Bank. The effects of adult scallop density-at-size and fecundity-at-size on egg production were compared among open and closed fishery areas, countries, and time periods before and after the closed areas were established. Estimated egg production was then used to define spawning conditions in a coupled biological-physical larval tracking model that simulated larval development, mortality, and dispersal. Results showed that order of magnitude increases in larval settlement after closure were facilitated by increases in size-dependant egg production inside and dispersal from Closed Areas I and II, but not Nantucket Lightship Closed Area. The distributions of both egg production and larval settlement became more uniform across the Bank, causing the relative contribution of Canadian larvae to US scallop aggregations to decrease after establishment of Closed Areas I and II. Decreases in small and medium-sized scallop density in Canada and decreases in large scallops over the US-Southern Flank after closure caused local declines in egg production but were not sufficient to negatively affect larval settlement at the regional scale. Our model suggests that the establishment of fishery closed areas on GB considerably strengthened larval supply and settlement within and among several adult scallop aggregations.

Fisheries Closed Areas Strengthen Scallop Larval Settlement and Connectivity Among Closed Areas and Across International Open Fishing Grounds: A Model Study

NASA Astrophysics Data System (ADS)

Davies, Kimberley T. A.; Gentleman, W. C.; DiBacco, C.; Johnson, C. L.

2015-09-01

This study examined whether a measured increase in average body size of adult sea scallops inside three fishery closed areas on Georges Bank (GB), United States (US), was sufficient to increase larval supply to closed areas and open fishing areas in both US and Canadian areas of the Bank. The effects of adult scallop density-at-size and fecundity-at-size on egg production were compared among open and closed fishery areas, countries, and time periods before and after the closed areas were established. Estimated egg production was then used to define spawning conditions in a coupled biological-physical larval tracking model that simulated larval development, mortality, and dispersal. Results showed that order of magnitude increases in larval settlement after closure were facilitated by increases in size-dependant egg production inside and dispersal from Closed Areas I and II, but not Nantucket Lightship Closed Area. The distributions of both egg production and larval settlement became more uniform across the Bank, causing the relative contribution of Canadian larvae to US scallop aggregations to decrease after establishment of Closed Areas I and II. Decreases in small and medium-sized scallop density in Canada and decreases in large scallops over the US-Southern Flank after closure caused local declines in egg production but were not sufficient to negatively affect larval settlement at the regional scale. Our model suggests that the establishment of fishery closed areas on GB considerably strengthened larval supply and settlement within and among several adult scallop aggregations.

p53 is required for brain growth but is dispensable for resistance to nutrient restriction during Drosophila larval development

PubMed Central

Contreras, Esteban G.; Sierralta, Jimena

2018-01-01

Background Animal growth is influenced by the genetic background and the environmental circumstances. How genes promote growth and coordinate adaptation to nutrient availability is still an open question. p53 is a transcription factor that commands the cellular response to different types of stresses. In adult Drosophila melanogaster, p53 regulates the metabolic adaptation to nutrient restriction that supports fly viability. Furthermore, the larval brain is protected from nutrient restriction in a phenomenon called ‘brain sparing’. Therefore, we hypothesised that p53 may regulate brain growth and show a protective role over brain development under nutrient restriction. Results Here, we studied the function of p53 during brain growth in normal conditions and in animals subjected to developmental nutrient restriction. We showed that p53 loss of function reduced animal growth and larval brain size. Endogenous p53 was expressed in larval neural stem cells, but its levels and activity were not affected by nutritional stress. Interestingly, p53 knockdown only in neural stem cells was sufficient to decrease larval brain growth. Finally, we showed that in p53 mutant larvae under nutrient restriction, the energy storage levels were not altered, and these larvae generated adults with brains of similar size than wild-type animals. Conclusions Using genetic approaches, we demonstrate that p53 is required for proper growth of the larval brain. This developmental role of p53 does not have an impact on animal resistance to nutritional stress since brain growth in p53 mutants under nutrient restriction is similar to control animals. PMID:29621246

p53 is required for brain growth but is dispensable for resistance to nutrient restriction during Drosophila larval development.

PubMed

Contreras, Esteban G; Sierralta, Jimena; Glavic, Alvaro

2018-01-01

Animal growth is influenced by the genetic background and the environmental circumstances. How genes promote growth and coordinate adaptation to nutrient availability is still an open question. p53 is a transcription factor that commands the cellular response to different types of stresses. In adult Drosophila melanogaster, p53 regulates the metabolic adaptation to nutrient restriction that supports fly viability. Furthermore, the larval brain is protected from nutrient restriction in a phenomenon called 'brain sparing'. Therefore, we hypothesised that p53 may regulate brain growth and show a protective role over brain development under nutrient restriction. Here, we studied the function of p53 during brain growth in normal conditions and in animals subjected to developmental nutrient restriction. We showed that p53 loss of function reduced animal growth and larval brain size. Endogenous p53 was expressed in larval neural stem cells, but its levels and activity were not affected by nutritional stress. Interestingly, p53 knockdown only in neural stem cells was sufficient to decrease larval brain growth. Finally, we showed that in p53 mutant larvae under nutrient restriction, the energy storage levels were not altered, and these larvae generated adults with brains of similar size than wild-type animals. Using genetic approaches, we demonstrate that p53 is required for proper growth of the larval brain. This developmental role of p53 does not have an impact on animal resistance to nutritional stress since brain growth in p53 mutants under nutrient restriction is similar to control animals.

Remotely Sensing Larval Population Dynamics of Rice Field Anophelines

NASA Technical Reports Server (NTRS)

Beck, Louisa R.; Dister, Sheri W.; Wood, Byron L.; Washino, Robert K.

1997-01-01

The primary objective of both studies was to determine if RS and GIS techniques could be used to distinguish between high and low larval-producing rice fields in California. Results of the first study suggested that early-season green-up and proximity to livestock pastures were positively correlated with high larval abundance. Based on the early-season spectral differences between high and low larval-producing fields, it appeared that canopy development and tillering influenced mosquito habitat quality. At that time, rice fields consisted of a mixture of plants and water, a combination that allowed An. freeborni females to lay eggs in partial sunlight, protected from both predators and wind. This established a population earlier in the season than in other, 'less-green' fields where tillering and plant emergence was too minimal for ovipositioning. The study also indicated the importance of the distance that a mosquito would have to fly in order to take a bloodmeal prior to ovipositing. These associations were fully explored in an expanded study two years later. The second study confirmed the positive relationship between early season canopy development and larval abundance, and also demonstrated the relationship between abundance and distance-to-pasture. The association between greenness (as measured using NDVI), distance-to-pasture, and abundance is illustrated. The second study also indicated the siginificance of the landscape context of rice fields for larval production. Fields that included opportunities for feeding and resting within the flight range of the mosquito had higher abundances than did fields that were in a homogeneous rice area.

Development, organization, and remodeling of phoronid muscles from embryo to metamorphosis (Lophotrochozoa: Phoronida).

PubMed

Temereva, Elena N; Tsitrin, Eugeni B

2013-04-24

The phoronid larva, which is called the actinotrocha, is one of the most remarkable planktotrophic larval types among marine invertebrates. Actinotrochs live in plankton for relatively long periods and undergo catastrophic metamorphosis, in which some parts of the larval body are consumed by the juvenile. The development and organization of the muscular system has never been described in detail for actinotrochs and for other stages in the phoronid life cycle. In Phoronopsis harmeri, muscular elements of the preoral lobe and the collar originate in the mid-gastrula stage from mesodermal cells, which have immigrated from the anterior wall of the archenteron. Muscles of the trunk originate from posterior mesoderm together with the trunk coelom. The organization of the muscular system in phoronid larvae of different species is very complex and consists of 14 groups of muscles. The telotroch constrictor, which holds the telotroch in the larval body during metamorphosis, is described for the first time. This unusual muscle is formed by apical myofilaments of the epidermal cells. Most larval muscles are formed by cells with cross-striated organization of myofibrils. During metamorphosis, most elements of the larval muscular system degenerate, but some of them remain and are integrated into the juvenile musculature. Early steps of phoronid myogenesis reflect the peculiarities of the actinotroch larva: the muscle of the preoral lobe is the first muscle to appear, and it is important for food capture. The larval muscular system is organized in differently in different phoronid larvae, but always exhibits a complexity that probably results from the long pelagic life, planktotrophy, and catastrophic metamorphosis. Degeneration of the larval muscular system during phoronid metamorphosis occurs in two ways, i.e., by complete or by incomplete destruction of larval muscular elements. The organization and remodeling of the muscular system in phoronids exhibits the combination of protostome-like and deuterostome-like features. This combination, which has also been found in the organization of some other systems in phoronids, can be regarded as an important characteristic and one that probably reflects the basal position of phoronids within the Lophotrochozoa.

Development, organization, and remodeling of phoronid muscles from embryo to metamorphosis (Lophotrochozoa: Phoronida)

PubMed Central

2013-01-01

Background The phoronid larva, which is called the actinotrocha, is one of the most remarkable planktotrophic larval types among marine invertebrates. Actinotrochs live in plankton for relatively long periods and undergo catastrophic metamorphosis, in which some parts of the larval body are consumed by the juvenile. The development and organization of the muscular system has never been described in detail for actinotrochs and for other stages in the phoronid life cycle. Results In Phoronopsis harmeri, muscular elements of the preoral lobe and the collar originate in the mid-gastrula stage from mesodermal cells, which have immigrated from the anterior wall of the archenteron. Muscles of the trunk originate from posterior mesoderm together with the trunk coelom. The organization of the muscular system in phoronid larvae of different species is very complex and consists of 14 groups of muscles. The telotroch constrictor, which holds the telotroch in the larval body during metamorphosis, is described for the first time. This unusual muscle is formed by apical myofilaments of the epidermal cells. Most larval muscles are formed by cells with cross-striated organization of myofibrils. During metamorphosis, most elements of the larval muscular system degenerate, but some of them remain and are integrated into the juvenile musculature. Conclusion Early steps of phoronid myogenesis reflect the peculiarities of the actinotroch larva: the muscle of the preoral lobe is the first muscle to appear, and it is important for food capture. The larval muscular system is organized in differently in different phoronid larvae, but always exhibits a complexity that probably results from the long pelagic life, planktotrophy, and catastrophic metamorphosis. Degeneration of the larval muscular system during phoronid metamorphosis occurs in two ways, i.e., by complete or by incomplete destruction of larval muscular elements. The organization and remodeling of the muscular system in phoronids exhibits the combination of protostome-like and deuterostome-like features. This combination, which has also been found in the organization of some other systems in phoronids, can be regarded as an important characteristic and one that probably reflects the basal position of phoronids within the Lophotrochozoa. PMID:23617418

Seasonal variations in larval biomass and biochemical composition of brown shrimp, Crangon crangon (Decapoda, Caridea), at hatching

NASA Astrophysics Data System (ADS)

Urzúa, Ángel; Anger, Klaus

2013-06-01

The "brown shrimp", Crangon crangon (Linnaeus 1758), is a benthic key species in the North Sea ecosystem, supporting an intense commercial fishery. Its reproductive pattern is characterized by a continuous spawning season from mid-winter to early autumn. During this extended period, C. crangon shows significant seasonal variations in egg size and embryonic biomass, which may influence larval quality at hatching. In the present study, we quantified seasonal changes in dry weight (W) and chemical composition (CHN, protein and lipid) of newly hatched larvae of C. crangon. Our data revealed significant variations, with maximum biomass values at the beginning of the hatching season (February-March), a decrease throughout spring (April-May) and a minimum in summer (June-September). While all absolute values of biomass and biochemical constituents per larva showed highly significant differences between months ( P < 0.001), CHN, protein and lipid concentrations (expressed as percentage values of dry weight) showed only marginally significant differences ( P < 0.05). According to generalized additive models (GAM), key variables of embryonic development exerted significant effects on larval condition at hatching: The larval carbon content (C) was positively correlated with embryonic carbon content shortly after egg-laying ( r 2 = 0.60; P < 0.001) and negatively with the average incubation temperature during the period of embryonic development ( r 2 = 0.35; P < 0.001). Additionally, water temperature ( r 2 = 0.57; P < 0.001) and food availability (phytoplankton C; r 2 = 0.39; P < 0.001) at the time of hatching were negatively correlated with larval C content at hatching. In conclusion, "winter larvae" hatching from larger "winter eggs" showed higher initial values of biomass compared to "summer larvae" originating from smaller "summer eggs". This indicates carry-over effects persisting from the embryonic to the larval phase. Since "winter larvae" are more likely exposed to poor nutritional conditions, intraspecific variability in larval biomass at hatching is interpreted as part of an adaptive reproductive strategy compensating for strong seasonality in plankton production and transitory periods of larval food limitation.

Early development and molecular plasticity in the Mediterranean sea urchin Paracentrotus lividus exposed to CO2-driven acidification.

PubMed

Martin, Sophie; Richier, Sophie; Pedrotti, Maria-Luiza; Dupont, Sam; Castejon, Charlotte; Gerakis, Yannis; Kerros, Marie-Emmanuelle; Oberhänsli, François; Teyssié, Jean-Louis; Jeffree, Ross; Gattuso, Jean-Pierre

2011-04-15

Ocean acidification is predicted to have significant effects on benthic calcifying invertebrates, in particular on their early developmental stages. Echinoderm larvae could be particularly vulnerable to decreased pH, with major consequences for adult populations. The objective of this study was to understand how ocean acidification would affect the initial life stages of the sea urchin Paracentrotus lividus, a common species that is widely distributed in the Mediterranean Sea and the NE Atlantic. The effects of decreased pH (elevated P(CO(2))) were investigated through physiological and molecular analyses on both embryonic and larval stages. Eggs and larvae were reared in Mediterranean seawater at six pH levels, i.e. pH(T) 8.1, 7.9, 7.7, 7.5, 7.25 and 7.0. Fertilization success, survival, growth and calcification rates were monitored over a 3 day period. The expression of genes coding for key proteins involved in development and biomineralization was also monitored. Paracentrotus lividus appears to be extremely resistant to low pH, with no effect on fertilization success or larval survival. Larval growth was slowed when exposed to low pH but with no direct impact on relative larval morphology or calcification down to pH(T) 7.25. Consequently, at a given time, larvae exposed to low pH were present at a normal but delayed larval stage. More surprisingly, candidate genes involved in development and biomineralization were upregulated by factors of up to 26 at low pH. Our results revealed plasticity at the gene expression level that allows a normal, but delayed, development under low pH conditions.

Impact of ocean warming and ocean acidification on larval development and calcification in the sea urchin Tripneustes gratilla.

PubMed

Sheppard Brennand, Hannah; Soars, Natalie; Dworjanyn, Symon A; Davis, Andrew R; Byrne, Maria

2010-06-29

As the oceans simultaneously warm, acidify and increase in P(CO2), prospects for marine biota are of concern. Calcifying species may find it difficult to produce their skeleton because ocean acidification decreases calcium carbonate saturation and accompanying hypercapnia suppresses metabolism. However, this may be buffered by enhanced growth and metabolism due to warming. We examined the interactive effects of near-future ocean warming and increased acidification/P(CO2) on larval development in the tropical sea urchin Tripneustes gratilla. Larvae were reared in multifactorial experiments in flow-through conditions in all combinations of three temperature and three pH/P(CO2) treatments. Experiments were placed in the setting of projected near future conditions for SE Australia, a global change hot spot. Increased acidity/P(CO2) and decreased carbonate mineral saturation significantly reduced larval growth resulting in decreased skeletal length. Increased temperature (+3 degrees C) stimulated growth, producing significantly bigger larvae across all pH/P(CO2) treatments up to a thermal threshold (+6 degrees C). Increased acidity (-0.3-0.5 pH units) and hypercapnia significantly reduced larval calcification. A +3 degrees C warming diminished the negative effects of acidification and hypercapnia on larval growth. This study of the effects of ocean warming and CO(2) driven acidification on development and calcification of marine invertebrate larvae reared in experimental conditions from the outset of development (fertilization) shows the positive and negative effects of these stressors. In simultaneous exposure to stressors the dwarfing effects of acidification were dominant. Reduction in size of sea urchin larvae in a high P(CO2) ocean would likely impair their performance with negative consequent effects for benthic adult populations.

Individual and mixture effects of selected pharmaceuticals on larval development of the estuarine shrimp Palaemon longirostris.

PubMed

González-Ortegón, Enrique; Blasco, Julian; Nieto, Elena; Hampel, Miriam; Le Vay, Lewis; Giménez, Luis

2016-01-01

Few ecotoxicological studies incorporate within the experimental design environmental variability and mixture effects when assessing the impact of pollutants on organisms. We have studied the combined effects of selected pharmaceutical compounds and environmental variability in terms of salinity and temperature on survival, development and body mass of larvae of the estuarine shrimp Palaemon longirostris. Drug residues found in coastal waters occur as mixture, and the evaluation of combined effects of simultaneously occurring compounds is indispensable for their environmental risk assessment. All larval stages of P. longirostris were exposed to the nonsteroidal anti-inflammatory drug (NSAID) diclofenac sodium (DS: 40 and 750 μg L(-1)), the lipid regulator clofibric acid (CA: 17 and 361 μg L(-1)) and the fungicide clotrimazole (CLZ: 0.14 and 4 μg L(-1)). We observed no effect on larval survival of P. longirostris with the tested pharmaceuticals. However, and in contrast to previous studies on larvae of the related marine species Palaemon serratus, CA affected development through an increase in intermoult duration and reduced growth without affecting larval body mass. These developmental effects in P. longirostris larvae were similar to those observed in the mixture of DS and CA confirming the toxic effects of CA. In the case of CLZ, its effects were similar to those observed previously in P. serratus: high doses affected development altering intermoult duration, tended to reduce the number of larval instars and decreased significantly the growth rate. This study suggests that an inter-specific life histories approach should be taken into account to assess the effect of emergent compounds in coastal waters. Copyright © 2015 Elsevier B.V. All rights reserved.

Impact of Ocean Warming and Ocean Acidification on Larval Development and Calcification in the Sea Urchin Tripneustes gratilla

PubMed Central

Sheppard Brennand, Hannah; Soars, Natalie; Dworjanyn, Symon A.; Davis, Andrew R.; Byrne, Maria

2010-01-01

Background As the oceans simultaneously warm, acidify and increase in P CO2, prospects for marine biota are of concern. Calcifying species may find it difficult to produce their skeleton because ocean acidification decreases calcium carbonate saturation and accompanying hypercapnia suppresses metabolism. However, this may be buffered by enhanced growth and metabolism due to warming. Methodology/Principal Findings We examined the interactive effects of near-future ocean warming and increased acidification/P CO2 on larval development in the tropical sea urchin Tripneustes gratilla. Larvae were reared in multifactorial experiments in flow-through conditions in all combinations of three temperature and three pH/P CO2 treatments. Experiments were placed in the setting of projected near future conditions for SE Australia, a global change hot spot. Increased acidity/P CO2 and decreased carbonate mineral saturation significantly reduced larval growth resulting in decreased skeletal length. Increased temperature (+3°C) stimulated growth, producing significantly bigger larvae across all pH/P CO2 treatments up to a thermal threshold (+6°C). Increased acidity (-0.3-0.5 pH units) and hypercapnia significantly reduced larval calcification. A +3°C warming diminished the negative effects of acidification and hypercapnia on larval growth. Conclusions and Significance This study of the effects of ocean warming and CO2 driven acidification on development and calcification of marine invertebrate larvae reared in experimental conditions from the outset of development (fertilization) shows the positive and negative effects of these stressors. In simultaneous exposure to stressors the dwarfing effects of acidification were dominant. Reduction in size of sea urchin larvae in a high P CO2 ocean would likely impair their performance with negative consequent effects for benthic adult populations. PMID:20613879

A genome-wide survey of maternal and embryonic transcripts during Xenopus tropicalis development.

PubMed

Paranjpe, Sarita S; Jacobi, Ulrike G; van Heeringen, Simon J; Veenstra, Gert Jan C

2013-11-06

Dynamics of polyadenylation vs. deadenylation determine the fate of several developmentally regulated genes. Decay of a subset of maternal mRNAs and new transcription define the maternal-to-zygotic transition, but the full complement of polyadenylated and deadenylated coding and non-coding transcripts has not yet been assessed in Xenopus embryos. To analyze the dynamics and diversity of coding and non-coding transcripts during development, both polyadenylated mRNA and ribosomal RNA-depleted total RNA were harvested across six developmental stages and subjected to high throughput sequencing. The maternally loaded transcriptome is highly diverse and consists of both polyadenylated and deadenylated transcripts. Many maternal genes show peak expression in the oocyte and include genes which are known to be the key regulators of events like oocyte maturation and fertilization. Of all the transcripts that increase in abundance between early blastula and larval stages, about 30% of the embryonic genes are induced by fourfold or more by the late blastula stage and another 35% by late gastrulation. Using a gene model validation and discovery pipeline, we identified novel transcripts and putative long non-coding RNAs (lncRNA). These lncRNA transcripts were stringently selected as spliced transcripts generated from independent promoters, with limited coding potential and a codon bias characteristic of noncoding sequences. Many lncRNAs are conserved and expressed in a developmental stage-specific fashion. These data reveal dynamics of transcriptome polyadenylation and abundance and provides a high-confidence catalogue of novel and long non-coding RNAs.

Effects of temperature on Anoplophora glabripennis (Coleoptera: Cerambycidae) larvae and pupae

Treesearch

M.A. Keena; P.M. Moore

2010-01-01

Developmental thresholds, degree-days for development, larval weights, and head capsule widths for each larval instar and the pupal stage of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) were studied at eight constant temperatures (5, 10, 15, 20, 25, 30, 35, and 40ºC) for two source populations (Ravenswood, Chicago, IL [...

COMPARATIVE EMBRYONIC AND LARVAL DEVELOPMENTAL RESPONSES OF AN ESTUARINE SHRIMP (PALAEMONETES PUGIO) TO THE JUVENILE HORMONE AGONIST, FENOXYCARB.

EPA Science Inventory

Grass shrimp (Palaemonetes pugio) were reared separately through both embryonic and total larval development during exposure to fenoxycarb at measured concentrations of <2.2 to 888 ug L-1. A fenoxycarb concentration of 888 ug L-1significantly (p<0.05) inhibited embryonic developm...

Habitat Hydrology and Geomorphology Control the Distribution of Malaria Vector Larvae in Rural Africa

PubMed Central

Hardy, Andrew J.; Gamarra, Javier G. P.; Cross, Dónall E.; Macklin, Mark G.; Smith, Mark W.; Kihonda, Japhet; Killeen, Gerry F.; Ling’ala, George N.; Thomas, Chris J.

2013-01-01

Background Larval source management is a promising component of integrated malaria control and elimination. This requires development of a framework to target productive locations through process-based understanding of habitat hydrology and geomorphology. Methods We conducted the first catchment scale study of fine resolution spatial and temporal variation in Anopheles habitat and productivity in relation to rainfall, hydrology and geomorphology for a high malaria transmission area of Tanzania. Results Monthly aggregates of rainfall, river stage and water table were not significantly related to the abundance of vector larvae. However, these metrics showed strong explanatory power to predict mosquito larval abundances after stratification by water body type, with a clear seasonal trend for each, defined on the basis of its geomorphological setting and origin. Conclusion Hydrological and geomorphological processes governing the availability and productivity of Anopheles breeding habitat need to be understood at the local scale for which larval source management is implemented in order to effectively target larval source interventions. Mapping and monitoring these processes is a well-established practice providing a tractable way forward for developing important malaria management tools. PMID:24312606

Ovicidal and larvicidal activity of extracts of Opuntia ficus-indica against gastrointestinal nematodes of naturally infected sheep.

PubMed

Féboli, Aline; Laurentiz, Antonio C; Soares, Suelen C S; Augusto, Jeferson G; Anjos, Luciano A; Magalhães, Lizandra G; Filardi, Rosemeire S; Laurentiz, Rosangela S

2016-08-15

This study describes the in vitro anthelmintic activity of extracts from Opuntia ficus indica against gastrointestinal nematodes of sheep. The anthelmintic activity was evaluated by inhibition of egg hatching, larval development and larval migration assays. The residual aqueous fractions from cladodes and fruits showed higher ovicidal activity with EC50 values of 7.2mg/mL and 1.5mg/mL, respectively. The aqueous, hexane, and ethyl acetate fractions from fruits and the aqueous fraction from cladodes inhibited 100% of larval development at the lowest concentration tested (1.56mg/mL). The crude cladode and fruit ethanolic extracts inhibited larval migration and showed EC50 values of 0.74mg/mL and 0.27mg/mL, respectively. Phytochemical screening detected high concentrations of alkaloids, tannins, flavonoids, and saponins in the fruits and cladodes. The results demonstrated that O. ficus exhibits anthelmintic activity in vitro, suggesting that, beyond its nutritional potential, this plant can also be an ally for parasite control in sheep. Copyright © 2016 Elsevier B.V. All rights reserved.

Habitat hydrology and geomorphology control the distribution of malaria vector larvae in rural Africa.

PubMed

Hardy, Andrew J; Gamarra, Javier G P; Cross, Dónall E; Macklin, Mark G; Smith, Mark W; Kihonda, Japhet; Killeen, Gerry F; Ling'ala, George N; Thomas, Chris J

2013-01-01

Larval source management is a promising component of integrated malaria control and elimination. This requires development of a framework to target productive locations through process-based understanding of habitat hydrology and geomorphology. We conducted the first catchment scale study of fine resolution spatial and temporal variation in Anopheles habitat and productivity in relation to rainfall, hydrology and geomorphology for a high malaria transmission area of Tanzania. Monthly aggregates of rainfall, river stage and water table were not significantly related to the abundance of vector larvae. However, these metrics showed strong explanatory power to predict mosquito larval abundances after stratification by water body type, with a clear seasonal trend for each, defined on the basis of its geomorphological setting and origin. Hydrological and geomorphological processes governing the availability and productivity of Anopheles breeding habitat need to be understood at the local scale for which larval source management is implemented in order to effectively target larval source interventions. Mapping and monitoring these processes is a well-established practice providing a tractable way forward for developing important malaria management tools.

A spatial age-structured model for describing sea lamprey (Petromyzon marinus) population dynamics

USGS Publications Warehouse

Robinson, Jason M.; Wilberg, Michael J.; Adams, Jean V.; Jones, Michael L.

2013-01-01

The control of invasive sea lampreys (Petromyzon marinus) presents large scale management challenges in the Laurentian Great Lakes. No modeling approach has been developed that describes spatial dynamics of lamprey populations. We developed and validated a spatial and age-structured model and applied it to a sea lamprey population in a large river in the Great Lakes basin. We considered 75 discrete spatial areas, included a stock-recruitment function, spatial recruitment patterns, natural mortality, chemical treatment mortality, and larval metamorphosis. Recruitment was variable, and an upstream shift in recruitment location was observed over time. From 1993–2011 recruitment, larval abundance, and the abundance of metamorphosing individuals decreased by 80, 84, and 86%, respectively. The model successfully identified areas of high larval abundance and showed that areas of low larval density contribute significantly to the population. Estimated treatment mortality was less than expected but had a large population-level impact. The results and general approach of this work have applications for sea lamprey control throughout the Great Lakes and for the restoration and conservation of native lamprey species globally.

CCDC-55 is required for larval development and distal tip cell migration in Caenorhabditis elegans.

PubMed

Kovacevic, Ismar; Ho, Richard; Cram, Erin J

2012-01-01

The Caenorhabditis elegans distal tip cells (DTCs) are an in vivo model for the study of developmentally regulated cell migration. In this study, we characterize a novel role for CCDC-55, a conserved coiled-coil domain containing protein, in DTC migration and larval development in C. elegans. Although animals homozygous for a probable null allele, ccdc-55(ok2851), display an early larval arrest, RNAi depletion experiments allow the analysis of later phenotypes and suggest that CCDC-55 is needed within the DTC for migration to cease at the end of larval morphogenesis. The ccdc-55 gene is found in an operon with rnf-121 and rnf-5, E3 ubiquitin ligases that target cell migration genes such as the β-integrin PAT-3. Genetic interaction studies using RNAi depletion and the deletion alleles rnf-121(ok848) and rnf-5(tm794) indicate that CCDC-55 and the RNF genes act at least partially in parallel to promote termination of cell migration in the adult DTC. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

CCDC-55 is required for larval development and distal tip cell migration in C. elegans

PubMed Central

Kovacevic, Ismar; Ho, Richard; Cram, Erin J.

2012-01-01

The C. elegans distal tip cells (DTCs) are an in vivo model for the study of developmentally regulated cell migration. In this study we characterize a novel role for CCDC-55, a conserved coiled-coil domain containing protein, in DTC migration and larval development in C. elegans. Although animals homozygous for a probable null allele, ccdc-55(ok2851), display an early larval arrest, RNAi depletion experiments allow the analysis of later phenotypes and suggest that CCDC-55 is needed within the DTC for migration to cease at the end of larval morphogenesis. The ccdc-55 gene is found in an operon with rnf-121 and rnf-5, E3 ubiquitin ligases that target cell migration genes such as the β-integrin PAT-3. Genetic interaction studies using RNAi depletion and the deletion alleles rnf-121(ok848) and rnf-5(tm794) indicate that CCDC-55 and the RNF genes act at least partially in parallel to promote termination of cell migration in the adult DTC. PMID:22285439

The complete larval development of the mud shrimp Upogebia vasquezi (Gebiidea: Upogebiidae) reared in the laboratory.

PubMed

De Oliveira, Danielly Brito; Martinelli-Lemos, Jussara Moretto; Abrunhosa, Fernando Araújo

2014-07-01

The larval development of Upogebia vasquezi consists of four zoeal stages and a megalopa. In the present study, each larval stage was described and illustrated in detail. The first two stages are re-described in order to provide a detailed comparison with the data available for this species recorded in a previous study. The morphological features of all the stages are compared with those of the larvae of other Upogebia species reported previously in the literature. Broad morphological similarities and distinctions were found among most Upogebia species. The main interspecific variations in the morphology of the zoeal stages are the segmentation pattern of the antennular endopod and number of aesthetascs, the number of setae on the scaphognathite and the presence or absence of a mandibular palp.

Transstadial Effects of Bti on Traits of Aedes aegypti and Infection with Dengue Virus

PubMed Central

Alto, Barry W.; Lord, Cynthia C.

2016-01-01

Most mosquito control efforts are primarily focused on reducing the adult population size mediated by reductions in the larval population, which should lower risk of disease transmission. Although the aim of larviciding is to reduce larval abundance and thus recruitment of adults, nonlethal effects on adults are possible, including transstadial effects on phenotypes of adults such as survival and pathogen infection and transmission. In addition, the mortality induced by control efforts may act in conjunction with other sources of mosquito mortality in nature. The consequences of these effects and interactions may alter the potential of the population to transmit pathogens. We tested experimentally the combined effects of a larvicide (Bacillus thuringiensis ssp. israelensis, Bti) and competition during the larval stages on subsequent Aedes aegypti (Linnaeus) traits, population performance, and susceptibility to dengue-1 virus infection. Ae. aegypti that survived exposure to Bti experienced accelerated development, were larger, and produced more eggs with increasing amounts of Bti, consistent with competitive release among surviving mosquitoes. Changing larval density had no significant interactive effect with Bti treatment on development and growth to adulthood. Larval density, but not Bti or treatment interaction, had a strong effect on survival of adult Ae. aegypti females. There were sharper declines in cumulative daily survival of adults from crowded than uncrowded larval conditions, suggesting that high competition conditions of larvae may be an impediment to transmission of dengue viruses. Rates of infection and dengue-1 virus disseminated infections were found to be 87±13% and 88±12%, respectively. There were no significant treatment effects on infection measurements. Our findings suggest that larvicide campaigns using Bti may reduce the number of emerged adults, but survivors will have a fitness advantage (growth, development, enhanced production of eggs) relative to conspecifics that are not under larvicide pressure. However, under most circumstances, these transstadial effects are unlikely to outweigh reductions in the adult population by Bti and altered risk of disease transmission. PMID:26871951

Occurrence of a mosquito vector in bird houses: Developmental consequences and potential epidemiological implications.

PubMed

Dieng, Hamady; Hassan, Rahimah Binti; Hassan, Ahmad Abu; Ghani, Idris Abd; Abang, Fatimah Bt; Satho, Tomomitsu; Miake, Fumio; Ahmad, Hamdan; Fukumitsu, Yuki; Hashim, Nur Aida; Zuharah, Wan Fatma; Kassim, Nur Faeza Abu; Majid, Abdul Hafiz Ab; Selvarajoo, Rekha; Nolasco-Hipolito, Cirilo; Ajibola, Olaide Olawunmi; Tuen, Andrew Alek

2015-05-01

Even with continuous vector control, dengue is still a growing threat to public health in Southeast Asia. Main causes comprise difficulties in identifying productive breeding sites and inappropriate targeted chemical interventions. In this region, rural families keep live birds in backyards and dengue mosquitoes have been reported in containers in the cages. To focus on this particular breeding site, we examined the capacity of bird fecal matter (BFM) from the spotted dove, to support Aedes albopictus larval growth. The impact of BFM larval uptake on some adult fitness traits influencing vectorial capacity was also investigated. In serial bioassays involving a high and low larval density (HD and LD), BFM and larval standard food (LSF) affected differently larval development. At HD, development was longer in the BFM environment. There were no appreciable mortality differences between the two treatments, which resulted in similar pupation and adult emergence successes. BFM treatment produced a better gender balance. There were comparable levels of blood uptake and egg production in BFM and LSF females at LD; that was not the case for the HD one, which resulted in bigger adults. BFM and LSF females displayed equivalent lifespans; in males, this parameter was shorter in those derived from the BFM/LD treatment. Taken together these results suggest that bird defecations successfully support the development of Ae. albopictus. Due to their cryptic aspects, containers used to supply water to encaged birds may not have been targeted by chemical interventions. Copyright © 2015 Elsevier B.V. All rights reserved.

Bean alpha-amylase inhibitors in transgenic peas inhibit development of pea weevil larvae.

PubMed

de Sousa-Majer, Maria José; Hardie, Darryl C; Turner, Neil C; Higgins, Thomas J V

2007-08-01

This glasshouse study used an improved larval measurement procedure to evaluate the impact of transgenic pea, Pisum sativum L., seeds expressing a-amylase inhibitor (AI)-1 or -2 proteins on pea weevil, Bruchus pisorum L. Seeds of transgenic 'Laura' and 'Greenfeast' peas expressing alpha-(AI)-1 reduced pea weevil survival by 93-98%. Larval mortality occurred at an early instar. Conversely, in nontransgenic cultivars, approximately 98-99% of the pea weevils emerged as adults. By measuring the head capsule size, we determined that larvae died at the first to early third instar in alpha-(AI)-1 transgenic peas, indicating that this inhibitor is highly effective in controlling this insect. By contrast, transgenic Laura and 'Dundale' expressing alpha-(AI)-2 did not affect pea weevil survival, but they did delay larval development. After 77 d of development, the head capsule size indicated that the larvae were still at the third instar stage in transgenic alpha-(AI)-2 peas, whereas adult bruchids had developed in the nontransgenic peas.

Development of the black soldier fly (Diptera: Stratiomyidae) in relation to temperature.

PubMed

Tomberlin, Jeffery K; Adler, Peter H; Myers, Heidi M

2009-06-01

The black soldier fly, Hermetia illucens L., was reared on a grain-based diet at 27, 30, and 36 degrees C. Survival of 4- to 6-d-old larvae to adults averaged 74-97% at 27 and 30 degrees C but was only 0.1% at 36 degrees C. Flies required a mean of approximately 4 d (11%) longer to complete larval and pupal development at 27 degrees C than at 30 degrees C. At 27 and 30 degrees C, females weighed an average of 17-19% more than males but required an average of 0.6-0.8 d (3.0-4.3%) longer to complete larval development. At both temperatures, adult females lived an average of approximately 3.5 d less than adult males. The duration of larval development was a significant predictor of adult longevity. Temperature differences of even 3 degrees C produce significant fitness tradeoffs for males and females, influencing life history attributes and having practical applications for forensic entomology.

Identifying the key biophysical drivers, connectivity outcomes, and metapopulation consequences of larval dispersal in the sea.

PubMed

Treml, Eric A; Ford, John R; Black, Kerry P; Swearer, Stephen E

2015-01-01

Population connectivity, which is essential for the persistence of benthic marine metapopulations, depends on how life history traits and the environment interact to influence larval production, dispersal and survival. Although we have made significant advances in our understanding of the spatial and temporal dynamics of these individual processes, developing an approach that integrates the entire population connectivity process from reproduction, through dispersal, and to the recruitment of individuals has been difficult. We present a population connectivity modelling framework and diagnostic approach for quantifying the impact of i) life histories, ii) demographics, iii) larval dispersal, and iv) the physical seascape, on the structure of connectivity and metapopulation dynamics. We illustrate this approach using the subtidal rocky reef ecosystem of Port Phillip Bay, were we provide a broadly-applicable framework of population connectivity and quantitative methodology for evaluating the relative importance of individual factors in determining local and system outcomes. The spatial characteristics of marine population connectivity are primarily influenced by larval mortality, the duration of the pelagic larval stage, and the settlement competency characteristics, with significant variability imposed by the geographic setting and the timing of larval release. The relative influence and the direction and strength of the main effects were strongly consistent among 10 connectivity-based metrics. These important intrinsic factors (mortality, length of the pelagic larval stage, and the extent of the precompetency window) and the spatial and temporal variability represent key research priorities for advancing our understanding of the connectivity process and metapopulation outcomes.

Obligate larval inhibition of Ostertagia gruehneri in Rangifer tarandus? Causes and consequences in an Arctic system.

PubMed

Hoar, Bryanne M; Eberhardt, Alexander G; Kutz, Susan J

2012-09-01

Larval inhibition is a common strategy of Trichostrongylidae nematodes that may increase survival of larvae during unfavourable periods and concentrate egg production when conditions are favourable for development and transmission. We investigated the propensity for larval inhibition in a population of Ostertagia gruehneri, the most common gastrointestinal Trichostrongylidae nematode of Rangifer tarandus. Initial experimental infections of 4 reindeer with O. gruehneri sourced from the Bathurst caribou herd in Arctic Canada suggested that the propensity for larval inhibition was 100%. In the summer of 2009 we infected 12 additional reindeer with the F1 and F2 generations of O. gruehneri sourced from the previously infected reindeer to further investigate the propensity of larval inhibition. The reindeer were divided into 2 groups and half were infected before the summer solstice (17 June) and half were infected after the solstice (16 July). Reindeer did not shed eggs until March 2010, i.e. 8 and 9 months post-infection. These results suggest obligate larval inhibition for at least 1 population of O. gruehneri, a phenomenon that has not been conclusively shown for any other trichostrongylid species. Obligate inhibition is likely to be an adaptation to both the Arctic environment and to a migratory host and may influence the ability of O. gruehneri to adapt to climate change.

Evaluation of nine genotypes of oilseed rape (Brassica napus L.) for larval infestation and performance of rape stem weevil (Ceutorhynchus napi Gyll.)

PubMed Central

Becker, Heiko C.; Vidal, Stefan

2017-01-01

The rape stem weevil, Ceutorhynchus napi Gyll., is a serious pest of winter oilseed rape (Brassica napus L.) crops in Europe causing severe yield loss. In currently used oilseed rape cultivars no resistance to C. napi has been identified. Resynthesized lines of B. napus have potential to broaden the genetic variability and may improve resistance to insect pests. In this study, the susceptibility to C. napi of three cultivars, one breeding line and five resynthesized lines of oilseed rape was compared in a semi-field plot experiment under multi-choice conditions. Plant acceptance for oviposition was estimated by counting the number of C. napi larvae in stems. The larval instar index and the dry body mass were assessed as indicators of larval performance. The extent of larval feeding within stems was determined by the stem injury coefficient. Morphological stem traits and stem contents of glucosinolates were assessed as potential mediators of resistance. The resynthesized line S30 had significantly fewer larvae than the cultivars Express617 and Visby and the resynthesized lines L122 and L16. The low level of larval infestation in S30 was associated with a low larval instar and stem injury index. Low numbers of larvae were not correlated with the length or diameter of stems, and the level of stem glucosinolates. As indicated by the low larval infestation and slow larval development the resistance of S30 to C. napi is based on both antixenotic and antibiotic properties of the genotypes. The resynthesized line S30 should therefore be introduced into B. napus breeding programs to enhance resistance against C. napi. PMID:28686731

Novel methodologies in marine fish larval nutrition.

PubMed

Conceição, Luis E C; Aragão, Cláudia; Richard, Nadège; Engrola, Sofia; Gavaia, Paulo; Mira, Sara; Dias, Jorge

2010-03-01

Major gaps in knowledge on fish larval nutritional requirements still remain. Small larval size, and difficulties in acceptance of inert microdiets, makes progress slow and cumbersome. This lack of knowledge in fish larval nutritional requirements is one of the causes of high mortalities and quality problems commonly observed in marine larviculture. In recent years, several novel methodologies have contributed to significant progress in fish larval nutrition. Others are emerging and are likely to bring further insight into larval nutritional physiology and requirements. This paper reviews a range of new tools and some examples of their present use, as well as potential future applications in the study of fish larvae nutrition. Tube-feeding and incorporation into Artemia of (14)C-amino acids and lipids allowed studying Artemia intake, digestion and absorption and utilisation of these nutrients. Diet selection by fish larvae has been studied with diets containing different natural stable isotope signatures or diets where different rare metal oxides were added. Mechanistic modelling has been used as a tool to integrate existing knowledge and reveal gaps, and also to better understand results obtained in tracer studies. Population genomics may assist in assessing genotype effects on nutritional requirements, by using progeny testing in fish reared in the same tanks, and also in identifying QTLs for larval stages. Functional genomics and proteomics enable the study of gene and protein expression under various dietary conditions, and thereby identify the metabolic pathways which are affected by a given nutrient. Promising results were obtained using the metabolic programming concept in early life to facilitate utilisation of certain nutrients at later stages. All together, these methodologies have made decisive contributions, and are expected to do even more in the near future, to build a knowledge basis for development of optimised diets and feeding regimes for different species of larval fish.

Impact of Diurnal Temperature Fluctuations during Larval Development on Adult Life History Traits and Insecticide Susceptibility in Two Vectors; Anopheles gambiae and Aedes aegypti

DTIC Science & Technology

2014-04-30

105 x CHAPTER 1: General Introduction THE THERMAL ENVIRONMENT The ambient temperature at which an organism must function can...forces an organism to operate outside the optimal temperature range for which its physiological processes are optimized to function under. Thermal...a specific insecticide. Some of these influences are relatively intuitive. For instance, larval development in the presence of adequate nutritional

Ontogenetic development in the morphology and behavior of loach ( Misgurnus anguillicaudatus) during early life stages

NASA Astrophysics Data System (ADS)

Gao, Lei; Duan, Ming; Cheng, Fei; Xie, Songguang

2014-09-01

Loach ( Misgurnus anguillicaudatus) are a commercially important fish in China and an ideal aquaculture species. However, culturists experience high larval and juvenile mortality during mass production. To provide insight into ways to improve larviculture techniques, we describe the morphological characteristics and behavior of loach during the larval and early juvenile stages. Yolksac larvae ranged from 2.8 to 4.0 mm body length (BL) between days 0 to 4; preflexion larvae ranged from 3.6 to 5.5 mm BL between days 4 to 6; flexion larvae ranged from 4.8 to 8.1 mm BL between days 5 and 14; and postflexion larvae ranged from 7.1 to 15.7 mm BL between days 11 to 27; the minimum length and age of juveniles was 14.1 mm BL and 23 d, respectively. Loach are demersal from hatch through to the early juvenile stages. A suite of morphological characteristics (e.g., external gill filament and ventral mouth opening) and behavioral traits have developed to adapt to demersal living. We observed positive allometric growth in eye diameter, head length, head height, and pectoral fin length during the early larval stages, reflecting the priorities in the development of the organs essential for survival. Our results provide a basis for developing techniques to improve the survival of larval and juvenile loach during mass production.

Long-term changes in food availability mediate the effects of temperature on growth, development and survival in striped marsh frog larvae: implications for captive breeding programmes

PubMed Central

Courtney Jones, Stephanie K.; Munn, Adam J.; Penman, Trent D.; Byrne, Phillip G.

2015-01-01

Food availability and temperature are known to trigger phenotypic change, but the interactive effects between these factors are only beginning to be considered. The aim of this study was to examine the independent and interactive effects of long-term stochastic food availability and water temperature on larval survivorship, growth and development of the striped marsh frog, Limnodynastes peronii. Larval L. peronii were reared in conditions of either constant or stochastic food availability and in water at three different temperatures (18, 22 and 26°C), and effects on survival, growth and development were quantified. Over the experimental period, larval growth rate was highest and survivorship lowest at the warmest temperature. However, changes in food availability mediated the effects of temperature, with slower larval growth and higher survivorship in stochastic food availability treatments. Tadpoles in the stochastic food availability treatments did not reach metamorphosis during the experimental period, suggesting that developmental stasis may have been induced by food restriction. Overall, these results demonstrate that changes in food availability alter the effects of water temperature on survival, growth and development. From an applied perspective, understanding how environmental factors interact to cause phenotypic change may assist with amphibian conservation by improving the number of tadpoles generated in captive breeding programmes. PMID:27293714

Role of specific activators of intestinal amino acid transport in Bombyx mori larval growth and nutrition.

PubMed

Leonardi, M G; Casartelli, M; Fiandra, L; Parenti, P; Giordana, B

2001-12-01

Nutrient absorption and its modulation are critical for animal growth. In this paper, we demonstrate that leucine methyl ester (Leu-OMe) can greatly increase the activity of the transport system responsible for the absorption of most essential amino acids in the larval midgut of the silkworm Bombyx mori. We investigated leucine uptake activation by Leu-OMe in brush border membrane vesicles and in the apical membrane of epithelial cells in the midgut incubated in vitro. Moreover, the addition of this strong activator of amino acid absorption to diet significantly affected larval growth. Silkworms fed on artificial diet supplemented with Leu-OMe reached maximum body weight 12-18 h before control larvae, and produced cocoon shells up to 20% heavier than those of controls. The activation of amino acid absorption plays an essential role in larval development so that larval growth and cocoon production similar to controls reared on an artificial diet with 25% of dry mulberry leaf powder were observed in silkworms fed on an artificial diet with only 5% of mulberry powder. Arch. Copyright 2001 Wiley-Liss, Inc.

Techniques and methods for estimating abundance of larval and metamorphosed sea lampreys in Great Lakes tributaries, 1995 to 2001

USGS Publications Warehouse

Slade, Jeffrey W.; Adams, Jean V.; Christie, Gavin C.; Cuddy, Douglas W.; Fodale, Michael F.; Heinrich, John W.; Quinlan, Henry R.; Weise, Jerry G.; Weisser, John W.; Young, Robert J.

2003-01-01

Before 1995, Great Lakes streams were selected for lampricide treatment based primarily on qualitative measures of the relative abundance of larval sea lampreys, Petromyzon marinus. New integrated pest management approaches required standardized quantitative measures of sea lamprey. This paper evaluates historical larval assessment techniques and data and describes how new standardized methods for estimating abundance of larval and metamorphosed sea lampreys were developed and implemented. These new methods have been used to estimate larval and metamorphosed sea lamprey abundance in about 100 Great Lakes streams annually and to rank them for lampricide treatment since 1995. Implementation of these methods has provided a quantitative means of selecting streams for treatment based on treatment cost and estimated production of metamorphosed sea lampreys, provided managers with a tool to estimate potential recruitment of sea lampreys to the Great Lakes and the ability to measure the potential consequences of not treating streams, resulting in a more justifiable allocation of resources. The empirical data produced can also be used to simulate the impacts of various control scenarios.

Ontogenetic loops in habitat use highlight the importance of littoral habitats for early life-stages of oceanic fishes in temperate waters

NASA Astrophysics Data System (ADS)

Polte, Patrick; Kotterba, Paul; Moll, Dorothee; von Nordheim, Lena

2017-02-01

General concepts of larval fish ecology in temperate oceans predominantly associate dispersal and survival to exogenous mechanisms such as passive drift along ocean currents. However, for tropical reef fish larvae and species in inland freshwater systems behavioural aspects of habitat selection are evidently important components of dispersal. This study is focused on larval Atlantic herring (Clupea harengus) distribution in a Baltic Sea retention area, free of lunar tides and directed current regimes, considered as a natural mesocosm. A Lorenz curve originally applied in socio-economics to describe demographic income distribution was adapted to a 20 year time-series of weekly larval herring distribution, revealing size-dependent spatial homogeneity. Additional quantitative sampling of distinct larval development stages across pelagic and littoral areas uncovered a loop in habitat use during larval ontogeny, revealing a key role of shallow littoral waters. With increasing rates of coastal change, our findings emphasize the importance of the littoral zone when considering reproduction of pelagic, ocean-going fish species; highlighting a need for more sensitive management of regional coastal zones.

Ontogenetic loops in habitat use highlight the importance of littoral habitats for early life-stages of oceanic fishes in temperate waters

PubMed Central

Polte, Patrick; Kotterba, Paul; Moll, Dorothee; von Nordheim, Lena

2017-01-01

General concepts of larval fish ecology in temperate oceans predominantly associate dispersal and survival to exogenous mechanisms such as passive drift along ocean currents. However, for tropical reef fish larvae and species in inland freshwater systems behavioural aspects of habitat selection are evidently important components of dispersal. This study is focused on larval Atlantic herring (Clupea harengus) distribution in a Baltic Sea retention area, free of lunar tides and directed current regimes, considered as a natural mesocosm. A Lorenz curve originally applied in socio-economics to describe demographic income distribution was adapted to a 20 year time-series of weekly larval herring distribution, revealing size-dependent spatial homogeneity. Additional quantitative sampling of distinct larval development stages across pelagic and littoral areas uncovered a loop in habitat use during larval ontogeny, revealing a key role of shallow littoral waters. With increasing rates of coastal change, our findings emphasize the importance of the littoral zone when considering reproduction of pelagic, ocean-going fish species; highlighting a need for more sensitive management of regional coastal zones. PMID:28205543

Inhibition of Helicoverpa zea (Lepidoptera: Noctuidae) Growth by Transgenic Corn Expressing Bt Toxins and Development of Resistance to Cry1Ab.

PubMed

Reisig, Dominic D; Reay-Jones, Francis P F

2015-08-01

Transgenic corn, Zea mays L., that expresses the Bacillus thuringiensis (Bt) toxin Cry1Ab is only moderately toxic to Helicoverpa zea (Boddie) and has been planted commercially since 1996. Growth and development of H. zea was monitored to determine potential changes in susceptibility to this toxin over time. Small plots of corn hybrids expressing Cry1F, Cry1F × Cry1Ab, Cry1Ab × Cry3Bb1, Cry1A.105 × Cry2Ab2 × Cry3Bb1, Cry1A.105 × Cry2Ab2, and Vip3Aa20 × Cry1Ab × mCry3A were planted in both 2012 and 2013 inNorth and South Carolina with paired non-Bt hybrids from the same genetic background. H. zea larvae were sampled on three time periods from ears and the following factors were measured: kernel area injured (cm(2)) by H. zea larvae, larval number per ear, larval weight, larval length, and larval head width. Pupae were sampled on a single time period and the following factors recorded: number per ear, weight, time to eclosion, and the number that eclosed. There was no reduction in larval weight, number of insect entering the pupal stadium, pupal weight, time to eclosion, and number of pupae able to successfully eclose to adulthood in the hybrid expressing Cry1Ab compared with a non-Bt paired hybrid. As Cry1Ab affected these in 1996, H. zea may be developing resistance to Cry1Ab in corn, although these results are not comprehensive, given the limited sampling period, size, and geography. We also found that the negative impacts on larval growth and development were greater in corn hybrids with pyramided traits compared with single traits. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Cardiorespiratory physiological phenotypic plasticity in developing air-breathing anabantid fishes (Betta splendens and Trichopodus trichopterus).

PubMed

Mendez-Sanchez, Jose F; Burggren, Warren W

2017-08-01

Developmental plasticity of cardiorespiratory physiology in response to chronic hypoxia is poorly understood in larval fishes, especially larval air-breathing fishes, which eventually in their development can at least partially "escape" hypoxia through air breathing. Whether the development air breathing makes these larval fishes less or more developmentally plastic than strictly water breathing larval fishes remains unknown. Consequently, developmental plasticity of cardiorespiratory physiology was determined in two air-breathing anabantid fishes ( Betta splendens and Trichopodus trichopterus ). Larvae of both species experienced an hypoxic exposure that mimicked their natural environmental conditions, namely chronic nocturnal hypoxia (12 h at 17 kPa or 14 kPa), with a daily return to diurnal normoxia. Chronic hypoxic exposures were made from hatching through 35 days postfertilization, and opercular and heart rates measured as development progressed. Opercular and heart rates in normoxia were not affected by chronic nocturnal hypoxic. However, routine oxygen consumption M˙O2 (~4  μ mol·O 2 /g per hour in normoxia in larval Betta ) was significantly elevated by chronic nocturnal hypoxia at 17 kPa but not by more severe (14 kPa) nocturnal hypoxia. Routine M˙O2 in Trichopodus (6-7  μ mol·O 2 /g per hour), significantly higher than in Betta , was unaffected by either level of chronic hypoxia. P Crit , the PO 2 at which M˙O2 decreases as ambient PO 2 falls, was measured at 35 dpf, and decreased with increasing chronic hypoxia in Betta , indicating a large, relatively plastic hypoxic tolerance. However, in contrast, P Crit in Trichopodus increased as rearing conditions grew more hypoxic, suggesting that hypoxic acclimation led to lowered hypoxic resistance. Species-specific differences in larval physiological developmental plasticity thus emerge between the relatively closely related Betta and Trichopodus Hypoxic rearing increased hypoxic tolerance in Betta , which inhabits temporary ponds with nocturnal hypoxia. Trichopodus , inhabiting more permanent oxygenated bodies of water, showed few responses to hypoxia, reflecting a lower degree of developmental phenotypic plasticity. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

Two distinct mechanisms silence chinmo in Drosophila neuroblasts and neuroepithelial cells to limit their self-renewal.

PubMed

Dillard, Caroline; Narbonne-Reveau, Karine; Foppolo, Sophie; Lanet, Elodie; Maurange, Cédric

2018-01-25

Whether common principles regulate the self-renewing potential of neural stem cells (NSCs) throughout the developing central nervous system is still unclear. In the Drosophila ventral nerve cord and central brain, asymmetrically dividing NSCs, called neuroblasts (NBs), progress through a series of sequentially expressed transcription factors that limits self-renewal by silencing a genetic module involving the transcription factor Chinmo. Here, we find that Chinmo also promotes neuroepithelium growth in the optic lobe during early larval stages by boosting symmetric self-renewing divisions while preventing differentiation. Neuroepithelium differentiation in late larvae requires the transcriptional silencing of chinmo by ecdysone, the main steroid hormone, therefore allowing coordination of neural stem cell self-renewal with organismal growth. In contrast, chinmo silencing in NBs is post-transcriptional and does not require ecdysone. Thus, during Drosophila development, humoral cues or tissue-intrinsic temporal specification programs respectively limit self-renewal in different types of neural progenitors through the transcriptional and post-transcriptional regulation of the same transcription factor. © 2018. Published by The Company of Biologists Ltd.

Postembryonic lineages of the Drosophila ventral nervous system: Neuroglian expression reveals the adult hemilineage associated fiber tracts in the adult thoracic neuromeres.

PubMed

Shepherd, David; Harris, Robin; Williams, Darren W; Truman, James W

2016-09-01

During larval life most of the thoracic neuroblasts (NBs) in Drosophila undergo a second phase of neurogenesis to generate adult-specific neurons that remain in an immature, developmentally stalled state until pupation. Using a combination of MARCM and immunostaining with a neurotactin antibody, Truman et al. (2004; Development 131:5167-5184) identified 24 adult-specific NB lineages within each thoracic hemineuromere of the larval ventral nervous system (VNS), but because of the neurotactin labeling of lineage tracts disappearing early in metamorphosis, they were unable extend the identification of these lineages into the adult. Here we show that immunostaining with an antibody against the cell adhesion molecule neuroglian reveals the same larval secondary lineage projections through metamorphosis and bfy identifying each neuroglian-positive tract at selected stages we have traced the larval hemilineage tracts for all three thoracic neuromeres through metamorphosis into the adult. To validate tract identifications we used the genetic toolkit developed by Harris et al. (2015; Elife 4) to preserve hemilineage-specific GAL4 expression patterns from larval into the adult stage. The immortalized expression proved a powerful confirmation of the analysis of the neuroglian scaffold. This work has enabled us to directly link the secondary, larval NB lineages to their adult counterparts. The data provide an anatomical framework that 1) makes it possible to assign most neurons to their parent lineage and 2) allows more precise definitions of the neuronal organization of the adult VNS based in developmental units/rules. J. Comp. Neurol. 524:2677-2695, 2016. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

Postembryonic lineages of the Drosophila ventral nervous system: Neuroglian expression reveals the adult hemilineage associated fiber tracts in the adult thoracic neuromeres

PubMed Central

Harris, Robin; Williams, Darren W.; Truman, James W.

2016-01-01

During larval life most of the thoracic neuroblasts (NBs) in Drosophila undergo a second phase of neurogenesis to generate adult‐specific neurons that remain in an immature, developmentally stalled state until pupation. Using a combination of MARCM and immunostaining with a neurotactin antibody, Truman et al. (2004; Development 131:5167–5184) identified 24 adult‐specific NB lineages within each thoracic hemineuromere of the larval ventral nervous system (VNS), but because of the neurotactin labeling of lineage tracts disappearing early in metamorphosis, they were unable extend the identification of these lineages into the adult. Here we show that immunostaining with an antibody against the cell adhesion molecule neuroglian reveals the same larval secondary lineage projections through metamorphosis and bfy identifying each neuroglian‐positive tract at selected stages we have traced the larval hemilineage tracts for all three thoracic neuromeres through metamorphosis into the adult. To validate tract identifications we used the genetic toolkit developed by Harris et al. (2015; Elife 4) to preserve hemilineage‐specific GAL4 expression patterns from larval into the adult stage. The immortalized expression proved a powerful confirmation of the analysis of the neuroglian scaffold. This work has enabled us to directly link the secondary, larval NB lineages to their adult counterparts. The data provide an anatomical framework that 1) makes it possible to assign most neurons to their parent lineage and 2) allows more precise definitions of the neuronal organization of the adult VNS based in developmental units/rules. J. Comp. Neurol. 524:2677–2695, 2016. © 2016 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc. PMID:26878258

A model of the evolution of larval feeding rate in Drosophila driven by conflicting energy demands.

PubMed

Mueller, Laurence D; Barter, Thomas T

2015-02-01

Energy allocation is believed to drive trade-offs in life history evolution. We develop a physiological and genetic model of energy allocation that drives evolution of feeding rate in a well-studied model system. In a variety of stressful environments Drosophila larvae adapt by altering their rate of feeding. Drosophila larvae adapted to high levels of ammonia, urea, and the presence of parasitoids evolve lower feeding rates. Larvae adapted to crowded conditions evolve higher feeding rates. Feeding rates should affect gross food intake, metabolic rates, and efficiency of food utilization. We develop a model of larval net energy intake as a function of feeding rates. We show that when there are toxic compounds in the larval food that require energy for detoxification, larvae can maximize their energy intake by slowing their feeding rates. While the reduction in feeding rates may increase development time and decrease competitive ability, we show that genotypes with lower feeding rates can be favored by natural selection if they have a sufficiently elevated viability in the toxic environment. This work shows how a simple phenotype, larval feeding rates, may be of central importance in adaptation to a wide variety of stressful environments via its role in energy allocation.

Effects of temperature on Anoplophora glabripennis (Coleoptera: Cerambycidae) larvae and pupae.

PubMed

Keena, M A; Moore, P M

2010-08-01

Developmental thresholds, degree-days for development, larval weights, and head capsule widths for each larval instar and the pupal stage of Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae) were studied at eight constant temperatures (5, 10, 15, 20, 25, 30, 35, and 40°C) for two source populations (Ravenswood, Chicago, IL [IL], and Bayside, Queens, NY [NY]). The estimated lower threshold temperature for development of instars 1-5 and the pupal stage was near 10°C and was near 12°C for the higher instars. Developmental rate was less temperature sensitive for instars 5-9 compared with instars 1-4. Development for all but the first instar was inhibited at constant temperatures >30°C, and all instars failed to develop at 40°C. Although the two source populations had similar responses to temperature, IL larvae were heavier than those from NY. Temperature and its influence on larval weight had profound impacts on whether a larva proceeded to pupation. Based on the temperature effects detailed here, larval development and pupation should be possible in most of the continental United States where suitable hosts are available. These data can be used to develop a degree-day model to estimate beetle phenology; however, at least 2°C should be added to air temperatures to adjust for the mediation of temperature by the wood. These data provide a basis for predicting the potential geographical range of this species and for developing phenological models to predict the timing of immature stages, both of which are important for management programs.

Differences in the timing of cardio-respiratory development determine whether marine gastropod embryos survive or die in hypoxia.

PubMed

Rudin-Bitterli, Tabitha S; Spicer, John I; Rundle, Simon D

2016-04-01

Physiological plasticity of early developmental stages is a key way by which organisms can survive and adapt to environmental change. We investigated developmental plasticity of aspects of the cardio-respiratory physiology of encapsulated embryos of a marine gastropod, Littorina obtusata, surviving exposure to moderate hypoxia (PO2 =8 kPa) and compared the development of these survivors with that of individuals that died before hatching. Individuals surviving hypoxia exhibited a slower rate of development and altered ontogeny of cardio-respiratory structure and function compared with normoxic controls (PO2 >20 kPa). The onset and development of the larval and adult hearts were delayed in chronological time in hypoxia, but both organs appeared earlier in developmental time and cardiac activity rates were greater. The velum, a transient, 'larval' organ thought to play a role in gas exchange, was larger in hypoxia but developed more slowly (in chronological time), and velar cilia-driven, rotational activity was lower. Despite these effects of hypoxia, 38% of individuals survived to hatching. Compared with those embryos that died during development, these surviving embryos had advanced expression of adult structures, i.e. a significantly earlier occurrence and greater activity of their adult heart and larger shells. In contrast, embryos that died retained larval cardio-respiratory features (the velum and larval heart) for longer in chronological time. Surviving embryos came from eggs with significantly higher albumen provisioning than those that died, suggesting an energetic component for advanced development of adult traits. © 2016. Published by The Company of Biologists Ltd.

Fussy Feeders: Phyllosoma Larvae of the Western Rocklobster (Panulirus cygnus) Demonstrate Prey Preference

PubMed Central

Saunders, Megan I.; Thompson, Peter A.; Jeffs, Andrew G.; Säwström, Christin; Sachlikidis, Nikolas; Beckley, Lynnath E.; Waite, Anya M.

2012-01-01

The Western Rocklobster (Panulirus cygnus) is the most valuable single species fishery in Australia and the largest single country spiny lobster fishery in the world. In recent years a well-known relationship between oceanographic conditions and lobster recruitment has become uncoupled, with significantly lower recruitment than expected, generating interest in the factors influencing survival and development of the planktonic larval stages. The nutritional requirements and wild prey of the planktotrophic larval stage (phyllosoma) of P. cygnus were previously unknown, hampering both management and aquaculture efforts for this species. Ship-board feeding trials of wild-caught mid-late stage P. cygnus phyllosoma in the eastern Indian Ocean, off the coast of Western Australia, were conducted in July 2010 and August-September 2011. In a series of experiments, phyllosoma were fed single and mixed species diets of relatively abundant potential prey items (chaetognaths, salps, and krill). Chaetognaths were consumed in 2–8 times higher numbers than the other prey, and the rate of consumption of chaetognaths increased with increasing concentration of prey. The highly variable lipid content of the phyllosoma, and the fatty acid profiles of the phyllosoma and chaetognaths, indicated they were from an oligotrophic oceanic food chain where food resources for macrozooplankton were likely to be constrained. Phyllosoma fed chaetognaths over 6 days showed significant changes in some fatty acids and tended to accumulate lipid, indicating an improvement in overall nutritional condition. The discovery of a preferred prey for P. cygnus will provide a basis for future oceanographic, management and aquaculture research for this economically and ecologically valuable species. PMID:22586479

Assessment of a liquid larval diet for rearing Dacus and Bactrocera species (Diptera:Tephritidae), in Western Africa

USDA-ARS?s Scientific Manuscript database

The fruit fly larval diet formulations developed by USDA-ARS were used in this study to compare with other artificial and natural diet to rear two Dacus species. The evaluation was based on the parameters of egg hatch, pupal production, adult emergence, flight ability, and productivity. This study s...

Efficacy and longevity of the newly developed catnip oil microcapsules against stable fly oviposition larval growth

USDA-ARS?s Scientific Manuscript database

The stable fly, Stomoxys calcitrans (Diptera: Muscidae), is one of the most important pests of cattle and costs U.S. cattle producers billions of dollars in losses annually. In this study, the efficacy of catnip oil encapsulated in gelatin in oviposition deterrence and larval growth inhibition in st...

A survey of the St. Louis River estuary with emphasis on non-indigenous species and habitat structure

EPA Science Inventory

As part of a larger study to develop a monitoring network for aquatic non-indigenous species (NIS), a comprehensive multi-gear survey of larval fish and macroinvertebrates in the St. Louis River estuary was conducted during summer 2012. A total of 139 larval fish samples and 118...

Seasonal Variation and Impact of Waste-Water Lagoons as Larval Habitat on the Population Dynamics of Culicoides sonorensis (Diptera:Ceratpogonidae) at Two Dairy Farms in Northern California

PubMed Central

Mayo, Christie E.; Osborne, Cameron J.; Mullens, Bradley A.; Gerry, Alec C.; Gardner, Ian A.; Reisen, William K.; Barker, Christopher M.; MacLachlan, N. James

2014-01-01

The Sacramento (northern Central) Valley of California (CA) has a hot Mediterranean climate and a diverse ecological landscape that is impacted extensively by human activities, which include the intensive farming of crops and livestock. Waste-water ponds, marshes, and irrigated fields associated with these agricultural activities provide abundant larval habitats for C. sonorensis midges, in addition to those sites that exist in the natural environment. Within this region, C. sonorensis is an important vector of bluetongue (BTV) and related viruses that adversely affect the international trade and movement of livestock, the economics of livestock production, and animal welfare. To characterize the seasonal dynamics of immature and adult C. sonorensis populations, abundance was monitored intensively on two dairy farms in the Sacramento Valley from August 2012– to July 2013. Adults were sampled every two weeks for 52 weeks by trapping (CDC style traps without light and baited with dry-ice) along N-S and E-W transects on each farm. One farm had large operational waste-water lagoons, whereas the lagoon on the other farm was drained and remained dry during the study. Spring emergence and seasonal abundance of adult C. sonorensis on both farms coincided with rising vernal temperature. Paradoxically, the abundance of midges on the farm without a functioning waste-water lagoon was increased as compared to abundance on the farm with a waste-water lagoon system, indicating that this infrastructure may not serve as the sole, or even the primary larval habitat. Adult midges disappeared from both farms from late November until May; however, low numbers of parous female midges were detected in traps set during daylight in the inter-seasonal winter period. This latter finding is especially critical as it provides a potential mechanism for the “overwintering” of BTV in temperate regions such as northern CA. Precise documentation of temporal changes in the annual abundance and dispersal of Culicoides midges is essential for the creation of models to predict BTV infection of livestock and to develop sound abatement strategies. PMID:24586925

Seasonal variation and impact of waste-water lagoons as larval habitat on the population dynamics of Culicoides sonorensis (Diptera:Ceratpogonidae) at two dairy farms in northern California.

PubMed

Mayo, Christie E; Osborne, Cameron J; Mullens, Bradley A; Gerry, Alec C; Gardner, Ian A; Reisen, William K; Barker, Christopher M; Maclachlan, N James

2014-01-01

The Sacramento (northern Central) Valley of California (CA) has a hot Mediterranean climate and a diverse ecological landscape that is impacted extensively by human activities, which include the intensive farming of crops and livestock. Waste-water ponds, marshes, and irrigated fields associated with these agricultural activities provide abundant larval habitats for C. sonorensis midges, in addition to those sites that exist in the natural environment. Within this region, C. sonorensis is an important vector of bluetongue (BTV) and related viruses that adversely affect the international trade and movement of livestock, the economics of livestock production, and animal welfare. To characterize the seasonal dynamics of immature and adult C. sonorensis populations, abundance was monitored intensively on two dairy farms in the Sacramento Valley from August 2012- to July 2013. Adults were sampled every two weeks for 52 weeks by trapping (CDC style traps without light and baited with dry-ice) along N-S and E-W transects on each farm. One farm had large operational waste-water lagoons, whereas the lagoon on the other farm was drained and remained dry during the study. Spring emergence and seasonal abundance of adult C. sonorensis on both farms coincided with rising vernal temperature. Paradoxically, the abundance of midges on the farm without a functioning waste-water lagoon was increased as compared to abundance on the farm with a waste-water lagoon system, indicating that this infrastructure may not serve as the sole, or even the primary larval habitat. Adult midges disappeared from both farms from late November until May; however, low numbers of parous female midges were detected in traps set during daylight in the inter-seasonal winter period. This latter finding is especially critical as it provides a potential mechanism for the "overwintering" of BTV in temperate regions such as northern CA. Precise documentation of temporal changes in the annual abundance and dispersal of Culicoides midges is essential for the creation of models to predict BTV infection of livestock and to develop sound abatement strategies.

Larval traits show temporally consistent constraints, but are decoupled from post-settlement juvenile growth, in an intertidal fish.

PubMed

Thia, Joshua A; Riginos, Cynthia; Liggins, Libby; Figueira, Will F; McGuigan, Katrina

2018-05-05

1.Complex life-cycles may evolve to dissociate distinct developmental phases in an organism's lifetime. However, genetic or environmental factors may restrict trait independence across life stages, constraining ontogenetic trajectories. Quantifying covariance across life-stages and their temporal variability is fundamental in understanding life-history phenotypes and potential distributions and consequences for selection. 2.We studied developmental constraints in an intertidal fish (Bathygobius cocosensis: Gobiidae) with a discrete pelagic larval phase and benthic juvenile phase. We tested whether traits occurring earlier in life affected those expressed later, and whether larval traits were decoupled from post-settlement juvenile traits. Sampling distinct cohorts from three annual breeding seasons afforded tests of temporally variability in trait covariance. 3.From otoliths (fish ear stones), we measured hatch size, larval duration, pelagic growth (larval traits) and early post-settlement growth (juvenile trait) in 124 juvenile B. cocoensis. We used path analyses to model trait relationships with respect to their chronological expression, comparing models among seasons. We also modelled the effect of season and hatch date on each individual trait to quantify their inherent variability. 4.Our path analyses demonstrated a decoupling of larval traits on juvenile growth. Within the larval phase, longer larval durations resulted in greater pelagic growth, and larger size-at-settlement. There was also evidence that larger hatch size might reduce larval durations, but this effect was only marginally significant. Although pelagic and post-settlement growth were decoupled, pelagic growth had post-settlement consequences: individuals with high pelagic growth were among the largest fish at settlement, and remained among the largest early post-settlement. We observed no evidence that trait relationships varied among breeding seasons, but larval duration differed among breeding seasons, and was shorter for larvae hatching later within each season. 5.Overall, we demonstrate mixed support for the expectation that traits in different life-stages are independent. While post-settlement growth was decoupled from larval traits, pelagic development had consequences for the size of newly settled juveniles. Temporal consistency in trait covariances implies that genetic and/or environmental factors influencing them were stable over our three-year study. Our work highlights the importance of individual developmental experiences and temporal variability in understanding population distributions of life-history traits. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Larval control of Anopheles (Nyssorhinchus) darlingi using granular formulation of Bacillus sphaericus in abandoned gold-miners excavation pools in the Brazilian Amazon rainforest.

PubMed

Galardo, Allan Kardec Ribeiro; Zimmerman, Robert; Galardo, Clícia Denis

2013-01-01

Use of a Bacillus sphaericus based mosquito larvicide was evaluated as an intervention for malaria vector control at a mining site in Amapá, Brazil. Impacts on larval and adult densities of the primary vector Anopheles darlingi were measured over the course of a 52 week study period. In Calçoene, State of Amapá, gold mining activity occurs in 19 mining sites in gold-miners of Lourenço. Large pools are formed in mining sites and naturally colonized by Anopheles darlingi. During one year, the impact of applications of VectoLex® CG to these larval sources was evaluated. Applications of 20kg/ha were made as needed, based on 10 immature (3rd, 4th instars and pupae) surveillance of health and established thresholds. One hundred percent initial control was observed 48h after each treatment. The pools received from 2-10 (5.3±1.6) treatments during the year. The average re-treatment interval in productive pools was 9.4±4.3 weeks. During weeks 3-52 of the study, mean density of late stage larvae was 78% and pupae were 93% lower in the treated pools than in untreated pools (p< 0.0001, n=51) while reduction of adult mosquitoes was 53% in comparison to the untreated area during the last five months of the study, which were the rainy season (p<0.001). VectoLex® CG reduced immature Anopheles darlingi infestation levels during the entire study period, and reduced adult mosquito populations during the rainy season.

Diel variations in the assemblage structure and foraging ecology of larval and 0+ year juvenile fishes in a man-made floodplain waterbody.

PubMed

Tewson, L H; Cowx, I G; Nunn, A D

2016-04-01

This study investigated diel variations in zooplankton composition and abundance, and the species composition, density, size structure, feeding activity, diet composition and prey selection of larval and 0+ year juvenile fishes in the littoral of a man-made floodplain waterbody over five 24 h periods within a 57 day period. There was a significant difference in the species composition of diurnal and nocturnal catches, with most species consistently peaking in abundance either during daylight or at night, reflecting their main activity period. There were no consistent diel patterns in assemblage structure or the abundance of some species, however, most likely, respectively, due to the phenology of fish hatching and ontogenetic shifts in diel behaviour or habitat use. There were few clear diel patterns in the diet composition or prey selection of larval and 0+ year juvenile roach Rutilus rutilus and perch Perca fluviatilis, with most taxa consistently selected or avoided irrespective of the time of day or night, and no obvious shift between planktonic and benthic food sources, but dietary overlap suggested that interspecific interactions were probably strongest at night. It is essential that sampling programmes account for the diel ecology of the target species, as diurnal surveys alone could produce inaccurate assessments of resource use. The relative lack of consistent diel patterns in this study suggests that multiple 24 h surveys are required in late spring and early summer to provide accurate assessments of 0+ year fish assemblage structure and foraging ecology. © 2016 The Fisheries Society of the British Isles.

Large-scale identification of differentially expressed genes during pupa development reveals solute carrier gene is essential for pupal pigmentation in Chilo suppressalis.

PubMed

Sun, Yang; Huang, Shuijin; Wang, Shuping; Guo, Dianhao; Ge, Chang; Xiao, Huamei; Jie, Wencai; Yang, Qiupu; Teng, Xiaolu; Li, Fei

2017-04-01

Insects undergo metamorphosis, involving an abrupt change in body structure through cell growth and differentiation. Rice stem stripped borer (SSB), Chilo suppressalis, is one of the most destructive rice pests. However, little is known about the regulation mechanism of metamorphosis development in this notorious insect pest. Here, we studied the expression of 22,197 SSB genes at seven time points during pupa development with a customized microarray, identifying 622 differentially expressed genes (DEG) during pupa development. Gene ontology (GO) analysis of these DEGs indicated that the genes related to substance metabolism were highly expressed in the early pupa, which participate in the physiological processes of larval tissue disintegration at these stages. In comparison, highly expressed genes in the late pupal stages were mainly associated with substance biosynthesis, consistent with adult organ formation at these stages. There were 27 solute carrier (SLC) genes that were highly expressed during pupa development. We knocked down SLC22A3 at the prepupal stage, demonstrating that silencing SLC22A3 induced a deficiency in pupa stiffness and pigmentation. The RNAi-treated individuals had white and soft pupa, suggesting that this gene has an essential role in pupal development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Diet and habitat use by age-0 deepwater sculpins in northern Lake Huron, Michigan and the Detroit River

USGS Publications Warehouse

Roseman, Edward F.

2014-01-01

Deepwater sculpins (Myoxocephalus thompsonii) are an important link in deepwater benthic foodwebs of the Great Lakes. Little information exists about deepwater sculpin spawning habits and early life history ecology due to difficulty in sampling deep offshore habitats. Larval and age-0 deepwater sculpins collected in northern Lake Huron and the Detroit River during 2007 were used to improve our understanding of their habitat use, diet, age, and growth. Peak larval density reached 8.4/1000 m3 in the Detroit River during April and was higher than that in Lake Huron. Offshore bottom trawls at DeTour and Hammond Bay first collected benthic age-0 deepwater sculpins in early September when fish were ≥ 25 mm TL. Otolith analysis revealed that hatch dates for pelagic larvae occurred during late March and larvae remained pelagic for 40 to 60 days. Diet of pelagic larvae (10–21 mm TL) was dominated by calanoid copepods at all sample locations. Diets of benthic age-0 fish varied by location and depth: Mysis and chironomids were prevalent in fish from Hammond Bay and the 91 m site at DeTour, but only chironomids were found in fish from the 37 m DeTour site. This work showed that nearshore epilimnetic sites were important for pelagic larvae and an ontogenetic shift from pelagic planktivore to benthivore occurred at about 25 mm TL in late summer. Age analysis showed that larvae remained pelagic long enough to be transported through the St. Clair–Detroit River system, Lake Erie, and the Niagara River, potentially contributing to populations in Lake Ontario.

Population Genetic Structure and Demographic History of Atrina pectinata Based on Mitochondrial DNA and Microsatellite Markers

PubMed Central

Xue, Dong-Xiu; Wang, Hai-Yan; Zhang, Tao; Liu, Jin-Xian

2014-01-01

The pen shell, Atrina pectinata, is one of the commercial bivalves in East Asia and thought to be recently affected by anthropogenic pressure (habitat destruction and/or fishing pressure). Information on its population genetic structure is crucial for the conservation of A. pectinata. Considering its long pelagic larval duration and iteroparity with high fecundity, the genetic structure for A. pectinata could be expected to be weak at a fine scale. However, the unusual oceanography in the coasts of China and Korea suggests potential for restricted dispersal of pelagic larvae and geographical differentiation. In addition, environmental changes associated with Pleistocene sea level fluctuations on the East China Sea continental shelf may also have strongly influenced historical population demography and genetic diversity of marine organisms. Here, partial sequences of the mitochondrial Cytochrome c oxidase subunit I (COI) gene and seven microsatellite loci were used to estimate population genetic structure and demographic history of seven samples from Northern China coast and one sample from North Korea coast. Despite high levels of genetic diversity within samples, there was no genetic differentiation among samples from Northern China coast and low but significant genetic differentiation between some of the Chinese samples and the North Korean sample. A late Pleistocene population expansion, probably after the Last Glacial Maximum, was also demonstrated for A. pectinata samples. No recent genetic bottleneck was detected in any of the eight samples. We concluded that both historical recolonization (through population range expansion and demographic expansion in the late Pleistocene) and current gene flow (through larval dispersal) were responsible for the weak level of genetic structure detected in A. pectinata. PMID:24789175

A developmental and energetic basis linking larval oyster shell formation to acidification sensitivity

NASA Astrophysics Data System (ADS)

Waldbusser, George G.; Brunner, Elizabeth L.; Haley, Brian A.; Hales, Burke; Langdon, Christopher J.; Prahl, Frederick G.

2013-05-01

Acidified waters are impacting commercial oyster production in the U.S. Pacific Northwest, and favorable carbonate chemistry conditions are predicted to become less frequent. Within 48 h of fertilization, unshelled Pacific oyster (Crassostrea gigas) larvae precipitate roughly 90% of their body weight as calcium carbonate. We measured stable carbon isotopes in larval shell and tissue and in algal food and seawater dissolved inorganic carbon in a longitudinal study of larval development and growth. Using these data and measured biochemical composition of larvae, we show that sensitivity of initial shell formation to ocean acidification results from diminished ability to isolate calcifying fluid from surrounding seawater, a limited energy budget and a strong kinetic demand for calcium carbonate precipitation. Our results highlight an important link between organism physiology and mineral kinetics in larval bivalves and suggest the consideration of mineral kinetics may improve understanding winners and losers in a high CO2 world.

A precocious adult visual center in the larva defines the unique optic lobe of the split-eyed whirligig beetle Dineutus sublineatus

PubMed Central

2013-01-01

Introduction Whirligig beetles (Coleoptera: Gyrinidae) are aquatic insects living on the water surface. They are equipped with four compound eyes, an upper pair viewing above the water surface and a lower submerged pair viewing beneath the water surface, but little is known about how their visual brain centers (optic lobes) are organized to serve such unusual eyes. We show here, for the first time, the peculiar optic lobe organization of the larval and adult whirligig beetle Dineutus sublineatus. Results The divided compound eyes of adult whirligig beetles supply optic lobes that are split into two halves, an upper half and lower half, comprising an upper and lower lamina, an upper and lower medulla and a bilobed partially split lobula. However, the lobula plate, a neuropil that in flies is known to be involved in mediating stabilized flight, exists only in conjunction with the lower lobe of the lobula. We show that, as in another group of predatory beetle larvae, in the whirligig beetle the aquatic larva precociously develops a lobula plate equipped with wide-field neurons. It is supplied by three larval laminas serving the three dorsal larval stemmata, which are adjacent to the developing upper compound eye. Conclusions In adult whirligig beetles, dual optic neuropils serve the upper aerial eyes and the lower subaquatic eyes. The exception is the lobula plate. A lobula plate develops precociously in the larva where it is supplied by inputs from three larval stemmata that have a frontal-upper field of view, in which contrasting objects such as prey items trigger a body lunge and mandibular grasp. This precocious lobula plate is lost during pupal metamorphosis, whereas another lobula plate develops normally during metamorphosis and in the adult is associated with the lower eye. The different roles of the upper and lower lobula plates in supporting, respectively, larval predation and adult optokinetic balance are discussed. Precocious development of the upper lobula plate represents convergent evolution of an ambush hunting lifestyle, as exemplified by the terrestrial larvae of tiger beetles (Cicindelinae), in which activation of neurons in their precocious lobula plates, each serving two large larval stemmata, releases reflex body extension and mandibular grasp. PMID:23421712

Expression analysis of the insulin-like growth factors I and II during embryonic and early larval development of turbot ( Scophthalmus maximus)

NASA Astrophysics Data System (ADS)

Wen, Haishen; Qi, Qian; Hu, Jian; Si, Yufeng; He, Feng; Li, Jifang

2015-04-01

The insulin-like growth factors I and II (IGF-I and IGF-II) are important proteins involved in fish growth and development. Here, we report the isolation of IGF-II and expression analysis of IGFs in turbot Scophthalmus maximus, aiming to clarify their function in embryonic and larval development of fish. The deduced IGF-II gene is 808 bp in full length, which encodes a protein of 219 amino acids and is 93% similar with that of Paralichthys olicaceus in amino acid sequence. The tissue abundance and the expression pattern of IGFs in a turbot at early development stages were investigated via reverse transcription-polymer chain reaction. Result showed that the IGF-I and IGF-II genes were widely expressed in tissues of S. maximus. IGF-I was detected in all tissues except intestines with the highest level in liver, while IGF-II transcript presented in all tissues except muscle. At the stages of embryonic and larval development, the mRNA levels of IGFs sharply increased from the stage of unfertilized egg to post larva, followed by a decrease with larval development. However, there was an increase in IGF-I at the embryonic stage and IGF-II at the gastrula stage, respectively. These results suggested that IGFs play important roles in cell growth and division of the turbot. Our study provides reference data for further investigation of growth regulation in turbot, which can guarantee better understanding of the physiological role that IGFs play in fish.

A toxicity assessment of hydroxyapatite nanoparticles on development and behaviour of Drosophila melanogaster

NASA Astrophysics Data System (ADS)

Pappus, S. Aurosman; Ekka, Basanti; Sahu, Swetapadma; Sabat, Debabrat; Dash, Priyabrat; Mishra, Monalisa

2017-04-01

The effects of oral intake of hydroxyapatite nanoparticles (HApNPs) were investigated on growth, development and behaviour of Drosophila. The Drosophila responses to various concentrations of HApNPs were compared. At lower concentrations, i.e. 5 mg L-1 more amount of oxidative stress was produced than that of highest concentration, i.e. 80 mg L-1. The increased amounts of oxidative stress reflect a higher amount of ROS production and increased cell damage within the larval gut. HApNPs was further shown to interfere with the calcium and phosphorus absorption pathway. Besides all these damage, HApNPs causes developmental delay in the late third instar larvae. The most significant anomaly was observed in pupae count, fly hatching after the feeding of HApNPs. Flies hatched from treated vials have decreased body weight with defective walking behaviour. Hatched flies have a phenotypic defect in the wing, eye and thorax of the bristles. Along with these changes, the adult fly becomes more prone towards stress. The findings hint that HApNPs persuade noxious effects and alter the development, structure, function and behaviour of the fly in a concentration-dependent manner.

Effects of metal and predator stressors in larval southern toads (Anaxyrus terrestris).

PubMed

Rumrill, Caitlin T; Scott, David E; Lance, Stacey L

2016-08-01

Natural and anthropogenic stressors typically do not occur in isolation; therefore, understanding ecological risk of contaminant exposure should account for potential interactions of multiple stressors. Realistically, common contaminants can also occur chronically in the environment. Because parental exposure to stressors may cause transgenerational effects on offspring, affecting their ability to cope with the same or novel environmental stressors, the exposure histories of generations preceding that being tested should be considered. To examine multiple stressor and parental exposure effects we employed a 2 × 2 × 2 factorial design in outdoor 1000-L mesocosms (n = 24). Larval southern toads (Anaxyrus terrestris), bred from parents collected from reference and metal-contaminated sites, were exposed to two levels of both an anthropogenic (copper-0, 30 µg/L Cu) and natural (predator cue - present/absent) stressor and reared to metamorphosis. Toads from the metal-contaminated parental source population were smaller at metamorphosis and had delayed development; i.e., a prolonged larval period. Similarly, larval Cu exposure also reduced size at metamorphosis and prolonged the larval period. We, additionally, observed a significant interaction between larval Cu and predator-cue exposure on larval period, wherein delayed emergence was only present in the 30-µg/L Cu treatments in the absence of predator cues. The presence of parental effects as well as an interaction between aquatic stressors on commonly measured endpoints highlight the importance of conducting multistressor studies across generations to obtain data that are more relevant to field conditions in order to determine population-level effects of contaminant exposure.

Effects of climate change on the survival of larval cod

NASA Astrophysics Data System (ADS)

Kristiansen, T.; Stock, C. A.; Drinkwater, K. F.; Curchitser, E. N.

2011-12-01

Understanding how climate change may impact important commercial fisheries is critical for developing sustainable fisheries management strategies. In this study, we used simulations from an Earth System Model (NOAA GFDL ESM2.1) coupled with an individual-based model (IBM) for larval fish to provide a first assessment of the potential importance of climate-change driven changes in primary productivity and temperature on cod recruitment in the North Atlantic to the year 2100. ESM model output was averaged for 5 regions, each with an area of 5x5 on a latitude-longitude grid, and representing the geographic boundaries of the current cod range. The physical and environmental data were incorporated into a mechanistic IBM used to simulate the critical early phases in the life of larval fish (e.g. cod) in a changing environment. Large phytoplankton production was predicted to decrease in most regions, thereby lowering the number of meso-zooplankton in the water column. Meso-zooplankton is the most important prey item for larval cod and a reduction in their numbers have strong impacts on larval cod survival. The combination of lowered prey abundance with increased energy requirement for growth and metabolism through increased temperature had a negative impact on cod recruitment in all modeled regions of the North Atlantic. The probability of survival past the larval stages was reduced with 20-30% at all five spawning grounds by the year 2100. Together, these results suggest climate change could have significant impacts on the survival of larval cod in the North Atlantic.

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

PubMed

Lamare, Miles D; Liddy, Michelle; Uthicke, Sven

2016-11-30

Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO 2 and ambient pCO 2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH (T) = 7.89-7.92), larvae developing in elevated pCO 2 vent conditions (pH (T) = 7.50-7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. © 2016 The Author(s).

In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites

PubMed Central

Liddy, Michelle; Uthicke, Sven

2016-01-01

Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO2 and ambient pCO2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH(T) = 7.89–7.92), larvae developing in elevated pCO2 vent conditions (pH(T) = 7.50–7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. PMID:27903867

The effect of live feeds bathed with the red seaweed Asparagopsis armata on the survival, growth and physiology status of Sparus aurata larvae.

PubMed

Castanho, S; Califano, G; Soares, F; Costa, R; Mata, L; Pousão-Ferreira, P; Ribeiro, L

2017-08-01

Larval rearing is affected by a wide range of microorganisms that thrive in larviculture systems. Some seaweed species have metabolites capable of reducing the bacterial load. However, no studies have yet tested whether including seaweed metabolites on larval rearing systems has any effects on the larvae development. This work assessed the development of Sparus aurata larvae fed preys treated with an Asparagopsis armata product. Live prey, Brachionus spp. and Artemia sp., were immersed in a solution containing 0.5% of a commercial extract of A. armata (Ysaline 100, YSA) for 30 min, before being fed to seabream larvae (n = 4 each). In the control, the live feed was immersed in clear water. Larval parameters such as growth, survival, digestive capacity (structural-histology and functional-enzymatic activity), stress level (cortisol content), non-specific immune response (lysozyme activity), anti-bacterial activity (disc-diffusion assay) and microbiota quantification (fish larvae gut and rearing water) were monitored. Fish larvae digestive capacity, stress level and non-specific immune response were not affected by the use of YSA. The number of Vibrionaceae was significantly reduced both in water and larval gut when using YSA. Growth was enhanced for YSA treatment, but higher mortality was also observed, especially until 10 days after hatching (DAH). The mortality peak observed at 8 DAH for both treatments, but higher for YSA, indicates larval higher susceptibility at this development stage, suggesting that lower concentrations of YSA should be used until 10 DAH. The application of YSA after 10 DAH onwards promotes a safer rearing environment.

Identification of Wnt Pathway Target Genes Regulating the Division and Differentiation of Larval Seam Cells and Vulval Precursor Cells in Caenorhabditis elegans

PubMed Central

Gorrepati, Lakshmi; Krause, Michael W.; Chen, Weiping; Brodigan, Thomas M.; Correa-Mendez, Margarita; Eisenmann, David M.

2015-01-01

The evolutionarily conserved Wnt/β-catenin signaling pathway plays a fundamental role during metazoan development, regulating numerous processes including cell fate specification, cell migration, and stem cell renewal. Wnt ligand binding leads to stabilization of the transcriptional effector β-catenin and upregulation of target gene expression to mediate a cellular response. During larval development of the nematode Caenorhabditis elegans, Wnt/β-catenin pathways act in fate specification of two hypodermal cell types, the ventral vulval precursor cells (VPCs) and the lateral seam cells. Because little is known about targets of the Wnt signaling pathways acting during larval VPC and seam cell differentiation, we sought to identify genes regulated by Wnt signaling in these two hypodermal cell types. We conditionally activated Wnt signaling in larval animals and performed cell type–specific "mRNA tagging" to enrich for VPC and seam cell–specific mRNAs, and then used microarray analysis to examine gene expression compared to control animals. Two hundred thirty-nine genes activated in response to Wnt signaling were identified, and we characterized 50 genes further. The majority of these genes are expressed in seam and/or vulval lineages during normal development, and reduction of function for nine genes caused defects in the proper division, fate specification, fate execution, or differentiation of seam cells and vulval cells. Therefore, the combination of these techniques was successful at identifying potential cell type–specific Wnt pathway target genes from a small number of cells and at increasing our knowledge of the specification and behavior of these C. elegans larval hypodermal cells. PMID:26048561

Identification of Wnt Pathway Target Genes Regulating the Division and Differentiation of Larval Seam Cells and Vulval Precursor Cells in Caenorhabditis elegans.

PubMed

Gorrepati, Lakshmi; Krause, Michael W; Chen, Weiping; Brodigan, Thomas M; Correa-Mendez, Margarita; Eisenmann, David M

2015-06-05

The evolutionarily conserved Wnt/β-catenin signaling pathway plays a fundamental role during metazoan development, regulating numerous processes including cell fate specification, cell migration, and stem cell renewal. Wnt ligand binding leads to stabilization of the transcriptional effector β-catenin and upregulation of target gene expression to mediate a cellular response. During larval development of the nematode Caenorhabditis elegans, Wnt/β-catenin pathways act in fate specification of two hypodermal cell types, the ventral vulval precursor cells (VPCs) and the lateral seam cells. Because little is known about targets of the Wnt signaling pathways acting during larval VPC and seam cell differentiation, we sought to identify genes regulated by Wnt signaling in these two hypodermal cell types. We conditionally activated Wnt signaling in larval animals and performed cell type-specific "mRNA tagging" to enrich for VPC and seam cell-specific mRNAs, and then used microarray analysis to examine gene expression compared to control animals. Two hundred thirty-nine genes activated in response to Wnt signaling were identified, and we characterized 50 genes further. The majority of these genes are expressed in seam and/or vulval lineages during normal development, and reduction of function for nine genes caused defects in the proper division, fate specification, fate execution, or differentiation of seam cells and vulval cells. Therefore, the combination of these techniques was successful at identifying potential cell type-specific Wnt pathway target genes from a small number of cells and at increasing our knowledge of the specification and behavior of these C. elegans larval hypodermal cells. Copyright © 2015 Gorrepati et al.

Morphology of the pre-imaginal stages of Lasioptera Donacis Coutin(Diptera: Cecidomyiidae), a candidate biocontrol agent of giant arundo cane

USDA-ARS?s Scientific Manuscript database

The larval stages of Lasioptera donacis Coutin consists of three instars, which develop within the mesophyll of the leaf sheaths of Arundo donax (L.) They feed aggregatively on mycelia of an endophytic fungus. The larval instars are similar to other members of the genus except for a three pronged sp...

Sex-dependent effects of larval food stress on adult performance under semi-natural conditions: only a matter of size?

PubMed

Rosa, Elena; Saastamoinen, Marjo

2017-07-01

Organisms with complex life-cycles acquire essential nutrients as juveniles, and hence even a short-term food stress during development can impose serious fitness costs apparent in adults. We used the Glanville fritillary butterfly to investigate the effects of larval food stress on adult performance under semi-natural conditions in a population enclosure. We were specifically interested in whether the negative effects observed were due to body mass reduction only or whether additional effects unrelated to pupal mass were evident. The two sexes responded differently to the larval food stress. In females, larval food stress reduced pupal mass and reproductive performance. The reduced reproductive performance was partially mediated by pupal mass reduction. Food stressed females also had reduced within-patch mobility, and this effect was not dependent on pupal mass. Conversely, food stress had no effect on male pupal mass, suggesting a full compensation via prolonged development time. Nonetheless, food stressed males were less likely to sire any eggs, potentially due to changes in their territorial behavior, as indicated by food stress also increasing male within-patch mobility (i.e., patrolling behavior). When males did sire eggs, the offspring number and viability were unaffected by male food stress treatment. Viability was in general higher for offspring sired by lighter males. Our study highlights how compensatory mechanisms after larval food stress can act in a sex-specific manner and that the alteration in body mass is only partially responsible for the reduced adult performance observed.

A Biophysical Model for Hawaiian Coral Reefs: Coupling Local Ecology, Larval Transport and Climate Change

NASA Astrophysics Data System (ADS)

Kapur, M. R.

2016-02-01

Simulative models of reef ecosystems have been used to evaluate ecological responses to a myriad of disturbance events, including fishing pressure, coral bleaching, invasion by alien species, and nutrient loading. The Coral Reef Scenario Evaluation Tool (CORSET), has been developed and instantiated for both the Meso-American Reef (MAR) and South China Sea (SCS) regions. This model is novel in that it accounts for the many scales at which reef ecosystem processes take place; is comprised of a "bottom-up" structure wherein complex behaviors are not pre-programmed, but emergent and highly portable to new systems. Local-scale dynamics are coupled across regions through larval connectivity matrices, derived sophisticated particle transport simulations that include key elements of larval behavior. By this approach, we are able to directly evaluate some of the potential consequences of larval connectivity patterns across a range of spatial scales and under multiple climate scenarios. This work develops and applies the CORSET (Coral Reef Scenario Evaluation Tool) to the Main Hawaiian Islands under a suite of climate and ecological scenarios. We introduce an adaptation constant into reef-building coral dynamics to simulate observed resiliencies to bleaching events. This presentation will share results from the model's instantiation under two Resource Concentration Pathway climate scenarios, with emphasis upon larval connectivity dynamics, emergent coral tolerance to increasing thermal anomalies, and patterns of spatial fishing closures. Results suggest that under a business-as-usual scenario, thermal tolerance and herbivore removal will have synergistic effects on reef resilience.

An open-source method to analyze optokinetic reflex responses in larval zebrafish.

PubMed

Scheetz, Seth D; Shao, Enhua; Zhou, Yangzhong; Cario, Clinton L; Bai, Qing; Burton, Edward A

2018-01-01

Optokinetic reflex (OKR) responses provide a convenient means to evaluate oculomotor, integrative and afferent visual function in larval zebrafish models, which are commonly used to elucidate molecular mechanisms underlying development, disease and repair of the vertebrate nervous system. We developed an open-source MATLAB-based solution for automated quantitative analysis of OKR responses in larval zebrafish. The package includes applications to: (i) generate sinusoidally-transformed animated grating patterns suitable for projection onto a cylindrical screen to elicit the OKR; (ii) determine and record the angular orientations of the eyes in each frame of a video recording showing the OKR response; and (iii) analyze angular orientation data from the tracking program to yield a set of parameters that quantify essential elements of the OKR. The method can be employed without modification using the operating manual provided. In addition, annotated source code is included, allowing users to modify or adapt the software for other applications. We validated the algorithms and measured OKR responses in normal larval zebrafish, showing good agreement with published quantitative data, where available. We provide the first open-source method to elicit and analyze the OKR in larval zebrafish. The wide range of parameters that are automatically quantified by our algorithms significantly expands the scope of quantitative analysis previously reported. Our method for quantifying OKR responses will be useful for numerous applications in neuroscience using the genetically- and chemically-tractable zebrafish model. Published by Elsevier B.V.

Swimming behavior of larval Medaka fish under microgravity

NASA Astrophysics Data System (ADS)

Furukawa, R.; Ijiri, K.

Fish exhibit looping and rolling behaviors when subjected to short periods of microgravity during parabolic flight. Strain-differences in the behavioral response of adult Medaka fish ( Oryzias latipes) were reported previously, however, there have been few studies of larval fish behavior under microgravity. In the present study, we investigated whether microgravity affects the swimming behavior of larvae at various ages (0 to 20 days after hatching), using different strains: HNI-II, HO5, ha strain, and variety of different strains (variety). The preliminary experiments were done in the ground laboratory: the development of eyesight was examined using optokinetic response for the different strains. The visual acuity of larvae improved drastically during 20 days after hatching. Strain differences of response were noted for the development of their visual acuity. In microgravity, the results were significantly different from those of adult Medaka. The larval fish appeared to maintain their orientation, except that a few of them exhibited looping and rolling behavior. Further, most larvae swam normally with their backs turning toward the light source (dorsal light response, DLR), and the rest of them stayed with their abdomen touching the surface of the container (ventral substrate response, VSR). For larval stages, strain-differences and age-differences in behavior were observed, but less pronounced than with adult fish under microgravity. Our observations suggest that adaptability of larval fish to the gravitational change and the mechanism of their postural control in microgravity are more variable than in adult fish.

Evidence for carry-over effects of predator exposure on pathogen transmission potential.

PubMed

Roux, Olivier; Vantaux, Amélie; Roche, Benjamin; Yameogo, Koudraogo B; Dabiré, Kounbobr R; Diabaté, Abdoulaye; Simard, Frederic; Lefèvre, Thierry

2015-12-22

Accumulating evidence indicates that species interactions such as competition and predation can indirectly alter interactions with other community members, including parasites. For example, presence of predators can induce behavioural defences in the prey, resulting in a change in susceptibility to parasites. Such predator-induced phenotypic changes may be especially pervasive in prey with discrete larval and adult stages, for which exposure to predators during larval development can have strong carry-over effects on adult phenotypes. To the best of our knowledge, no study to date has examined possible carry-over effects of predator exposure on pathogen transmission. We addressed this question using a natural food web consisting of the human malaria parasite Plasmodium falciparum, the mosquito vector Anopheles coluzzii and a backswimmer, an aquatic predator of mosquito larvae. Although predator exposure did not significantly alter mosquito susceptibility to P. falciparum, it incurred strong fitness costs on other key mosquito life-history traits, including larval development, adult size, fecundity and longevity. Using an epidemiological model, we show that larval predator exposure should overall significantly decrease malaria transmission. These results highlight the importance of taking into account the effect of environmental stressors on disease ecology and epidemiology. © 2015 The Author(s).

High resolution microscopy reveals significant impacts of ocean acidification and warming on larval shell development in Laternula elliptica.

PubMed

Bylenga, Christine H; Cummings, Vonda J; Ryan, Ken G

2017-01-01

Environmental stressors impact marine larval growth rates, quality and sizes. Larvae of the Antarctic bivalve, Laternula elliptica, were raised to the D-larvae stage under temperature and pH conditions representing ambient and end of century projections (-1.6°C to +0.4°C and pH 7.98 to 7.65). Previous observations using light microscopy suggested pH had no influence on larval abnormalities in this species. Detailed analysis of the shell using SEM showed that reduced pH is in fact a major stressor during development for this species, producing D-larvae with abnormal shapes, deformed shell edges and irregular hinges, cracked shell surfaces and even uncalcified larvae. Additionally, reduced pH increased pitting and cracking on shell surfaces. Thus, apparently normal larvae may be compromised at the ultrastructural level and these larvae would be in poor condition at settlement, reducing juvenile recruitment and overall survival. Elevated temperatures increased prodissoconch II sizes. However, the overall impacts on larval shell quality and integrity with concurrent ocean acidification would likely overshadow any beneficial results from warmer temperatures, limiting populations of this prevalent Antarctic species.

Evidence for carry-over effects of predator exposure on pathogen transmission potential

PubMed Central

Roux, Olivier; Vantaux, Amélie; Roche, Benjamin; Yameogo, Koudraogo B.; Dabiré, Kounbobr R.; Diabaté, Abdoulaye; Simard, Frederic; Lefèvre, Thierry

2015-01-01

Accumulating evidence indicates that species interactions such as competition and predation can indirectly alter interactions with other community members, including parasites. For example, presence of predators can induce behavioural defences in the prey, resulting in a change in susceptibility to parasites. Such predator-induced phenotypic changes may be especially pervasive in prey with discrete larval and adult stages, for which exposure to predators during larval development can have strong carry-over effects on adult phenotypes. To the best of our knowledge, no study to date has examined possible carry-over effects of predator exposure on pathogen transmission. We addressed this question using a natural food web consisting of the human malaria parasite Plasmodium falciparum, the mosquito vector Anopheles coluzzii and a backswimmer, an aquatic predator of mosquito larvae. Although predator exposure did not significantly alter mosquito susceptibility to P. falciparum, it incurred strong fitness costs on other key mosquito life-history traits, including larval development, adult size, fecundity and longevity. Using an epidemiological model, we show that larval predator exposure should overall significantly decrease malaria transmission. These results highlight the importance of taking into account the effect of environmental stressors on disease ecology and epidemiology. PMID:26674956

A Video-Tracking Analysis-Based Behavioral Assay for Larvae of Anopheles pseudopunctipennis and Aedes aegypti (Diptera: Culicidae).

PubMed

Gonzalez, Paula V; Alvarez Costa, Agustín; Masuh, Héctor M

2017-05-01

Aedes aegypti (L.) is the primary vector of dengue, yellow fever, Zika, and chikungunya viruses, whereas Anopheles pseudopunctipennis (Theobald) is the principal vector for malaria in Latin America. The larval stage of these mosquitoes occurs in very different development habitats, and the study of their respective behaviors could give us valuable information to improve larval control. The aim of this study was to set up a bioassay to study basic larval behaviors using a video-tracking software. Larvae of An. pseudopunctipennis came from two localities in Salta Province, Argentina, while Ae. aegypti larvae were of the Rockefeller laboratory strain. Behaviors of individual fourth-instar larvae were documented in an experimental petri dish arena using EthoVision XT10.1 video-tracking software. The overall level of movement of larval An. pseudopunctipennis was lower than that for Ae. aegypti, and, while moving, larval An. pseudopunctipennis spent significantly more time swimming near the wall of the arena (thigmotaxis). This is the first study that analyzes the behavior of An. pseudopunctipennis larvae. The experimental system described here may be useful for future studies on the effect of physiological, toxicological, and chemosensory stimuli on larval behaviors. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Neurodevelopmental Low-dose Bisphenol A Exposure Leads to Early Life-stage Hyperactivity and Learning Deficits in Adult Zebrafish

PubMed Central

Saili, Katerine S.; Corvi, Margaret M.; Weber, Daniel N.; Patel, Ami U.; Das, Siba R.; Przybyla, Jennifer; Anderson, Kim A.; Tanguay, Robert L.

2011-01-01

Developmental bisphenol A (BPA) exposure has been implicated in adverse behavior and learning deficits. The mode of action underlying these effects is unclear. The zebrafish model was employed to investigate the neurobehavioral effects of developmental bisphenol A (BPA) exposure. The objectives of this study were to identify whether low-dose, developmental BPA exposure affects larval zebrafish locomotor behavior and whether learning deficits occur in adults exposed during development. Two control compounds, 17β-estradiol (an estrogen receptor ligand) and GSK4716 (a synthetic estrogen related receptor gamma ligand), were included. Larval toxicity assays were used to determine appropriate BPA, 17β-estradiol, and GSK4716 concentrations for behavior testing. BPA tissue uptake was analyzed using HPLC and lower doses were extrapolated using a linear regression analysis. Larval behavior tests were conducted using a ViewPoint Zebrabox. Adult learning tests were conducted using a custom-built T-maze. BPA exposure to ≤30 μM was nonteratogenic in zebrafish. Neurodevelopmental BPA exposure to 0.01, 0.1, or 1 μM led to larval hyperactivity or learning deficits in adult zebrafish. Exposure to 0.1 μM 17β-estradiol or GSK4716 also led to larval hyperactivity. This study demonstrates the efficacy of using the larval zebrafish model for studying the neurobehavioral effects of low-dose developmental BPA exposure. PMID:22108044

Life history linked to immune investment in developing amphibians.

PubMed

Woodhams, Douglas C; Bell, Sara C; Bigler, Laurent; Caprioli, Richard M; Chaurand, Pierre; Lam, Brianna A; Reinert, Laura K; Stalder, Urs; Vazquez, Victoria M; Schliep, Klaus; Hertz, Andreas; Rollins-Smith, Louise A

2016-01-01

The broad diversity of amphibian developmental strategies has been shaped, in part, by pathogen pressure, yet trade-offs between the rate of larval development and immune investment remain poorly understood. The expression of antimicrobial peptides (AMPs) in skin secretions is a crucial defense against emerging amphibian pathogens and can also indirectly affect host defense by influencing the composition of skin microbiota. We examined the constitutive or induced expression of AMPs in 17 species at multiple life-history stages. We found that AMP defenses in tadpoles of species with short larval periods (fast pace of life) were reduced in comparison with species that overwinter as tadpoles and grow to a large size. A complete set of defensive peptides emerged soon after metamorphosis. These findings support the hypothesis that species with a slow pace of life invest energy in AMP production to resist potential pathogens encountered during the long larval period, whereas species with a fast pace of life trade this investment in defense for more rapid growth and development.

EGF-mediated EGFR/ERK signaling pathway promotes germinative cell proliferation in Echinococcus multilocularis that contributes to larval growth and development.

PubMed

Cheng, Zhe; Liu, Fan; Li, Xiu; Dai, Mengya; Wu, Jianjian; Guo, Xinrui; Tian, Huimin; Heng, Zhijie; Lu, Ying; Chai, Xiaoli; Wang, Yanhai

2017-02-01

Larvae of the tapeworm E. multilocularis cause alveolar echinococcosis (AE), one of the most lethal helminthic infections in humans. A population of stem cell-like cells, the germinative cells, is considered to drive the larval growth and development within the host. The molecular mechanisms controlling the behavior of germinative cells are largely unknown. Using in vitro cultivation systems we show here that the EGFR/ERK signaling in the parasite can promote germinative cell proliferation in response to addition of human EGF, resulting in stimulated growth and development of the metacestode larvae. Inhibition of the signaling by either the EGFR inhibitors CI-1033 and BIBW2992 or the MEK/ERK inhibitor U0126 impairs germinative cell proliferation and larval growth. These data demonstrate the contribution of EGF-mediated EGFR/ERK signaling to the regulation of germinative cells in E. multilocularis, and suggest the EGFR/ERK signaling as a potential therapeutic target for AE and perhaps other human cestodiasis.

The specific diagnosis of gastrointestinal nematode infections in livestock: larval culture technique, its limitations and alternative DNA-based approaches.

PubMed

Roeber, Florian; Kahn, Lewis

2014-10-15

The specific diagnosis of gastrointestinal nematode infections in ruminants is routinely based on larval culture technique and on the morphological identification of developed third-stage larvae. However, research on the ecology and developmental requirements of different species suggests that environmental conditions (e.g., temperature and humidity) for optimal development to occur vary between the different species. Thus, employing a common culture protocol for all species will favour the development of certain species over others and can cause a biased result in particular when species proportions in a mixed infection are to be determined. Furthermore, the morphological identification of L3 larvae is complicated by a lack of distinctive, obvious features that would allow the identification of all key species. In the present paper we review in detail the potential limitations of larval culture technique and morphological identification and provide account to some modern molecular alternatives to the specific diagnosis of gastrointestinal nematode infection in ruminants. Copyright © 2014 Elsevier B.V. All rights reserved.

Potential of the Lectin/Inhibitor Isolated from Crataeva tapia Bark (CrataBL) for Controlling Callosobruchus maculatus Larva Development.

PubMed

Nunes, Natalia N S; Ferreira, Rodrigo S; Silva-Lucca, Rosemeire A; de Sá, Leonardo F R; de Oliveira, Antônia Elenir A; Correia, Maria Tereza dos S; Paiva, Patrícia Maria G; Wlodawer, Alexander; Oliva, Maria Luiza V

2015-12-09

Callosobruchus maculatus is an important predator of cowpeas. Due to infestation during storage, this insect affects the quality of seed and crop yield. This study aimed to investigate the effects of CrataBL, a multifunction protein isolated from Crataeva tapia bark, on C. maculatus larva development. The protein, which is stable even in extreme pH conditions, showed toxic activity, reducing the larval mass 45 and 70% at concentrations of 0.25 and 1.0% (w/w), respectively. Acting as an inhibitor, CrataBL decreased by 39% the activity of cysteine proteinases from larval gut. Conversely, the activity of serine proteinases was increased about 8-fold. The toxic properties of CrataBL may also be attributed to its capacity of binding to glycoproteins or glycosaminoglycans. Such binding interferes with larval metabolism, because CrataBL-FITC was found in the fat body, Malpighian tubules, and feces of larvae. These results demonstrate the potential of this protein for controlling larva development.

Apo-14 is required for digestive system organogenesis during fish embryogenesis and larval development.

PubMed

Xia, Jian-Hong; Liu, Jing-Xia; Zhou, Li; Li, Zhi; Gui, Jian-Fang

2008-01-01

Apo-14 is a fish-specific apolipoprotein and its biological function remains unknown. In this study, CagApo-14 was cloned from gibel carp (Carassius auratus gibelio) and its expression pattern was investigated during embryogenesis and early larval development. The CagApo-14 transcript and its protein product were firstly localized in the yolk syncytial layer at a high level during embryogenesis, and then found to be restricted to the digestive system including liver and intestine in later embryos and early larvae. Immunofluorescence staining in larvae and adults indicated that Cag Apo-14 protein was predominantly synthesized in and excreted from sinusoidal endothelial cells of liver tissue. Morpholino knockdown of Cag Apo-14 resulted in severe disruption of digestive organs including liver, intestine, pancreas and swim bladder. Moreover, yolk lipid transportation and utilization were severely affected in the Cag Apo-14 morphants. Overall, this data indicates that Cag Apo-14 is required for digestive system organogenesis during fish embryogenesis and larval development.

Activation of Sox3 Gene by Thyroid Hormone in the Developing Adult Intestinal Stem Cell During Xenopus Metamorphosis

PubMed Central

Sun, Guihong; Fu, Liezhen; Wen, Luan

2014-01-01

The maturation of the intestine into the adult form involves the formation of adult stem cells in a thyroid hormone (T3)-dependent process in vertebrates. In mammals, this takes place during postembryonic development, a period around birth when the T3 level peaks. Due to the difficulty of manipulating late-stage, uterus-enclosed embryos, very little is known about the development of the adult intestinal stem cells. Interestingly, the remodeling of the intestine during the T3-dependent amphibian metamorphosis mimics the maturation of mammalian intestine. Our earlier microarray studies in Xenopus laevis revealed that the transcription factor SRY (sex-determining region Y)-box 3 (Sox3), well known for its involvement in neural development, was upregulated in the intestinal epithelium during metamorphosis. Here, we show that Sox3 is highly and specifically expressed in the developing adult intestinal progenitor/stem cells. We further show that its induction by T3 is independent of new protein synthesis, suggesting that Sox3 is directly activated by liganded T3 receptor. Thus, T3 activates Sox3 as one of the earliest changes in the epithelium, and Sox3 in turn may facilitate the dedifferentiation of the larval epithelial cells into adult stem cells. PMID:25211587

From Embryo to Adult: piRNA-Mediated Silencing throughout Germline Development in Drosophila

PubMed Central

Marie, Pauline P.; Ronsseray, Stéphane; Boivin, Antoine

2016-01-01

In metazoan germ cells, transposable element activity is repressed by small noncoding PIWI-associated RNAs (piRNAs). Numerous studies in Drosophila have elucidated the mechanism of this repression in the adult germline. However, when and how transposable element repression is established during germline development has not been addressed. Here, we show that homology-dependent trans silencing is active in female primordial germ cells from late embryogenesis through pupal stages, and that genes related to the adult piRNA pathway are required for silencing during development. In larval gonads, we detect rhino-dependent piRNAs indicating de novo biogenesis of functional piRNAs during development. Those piRNAs exhibit the molecular signature of the “ping-pong” amplification step. Moreover, we show that Heterochromatin Protein 1a is required for the production of piRNAs coming from telomeric transposable elements. Furthermore, as in adult ovaries, incomplete, bimodal, and stochastic repression resembling variegation can occur at all developmental stages. Clonal analysis indicates that the repression status established in embryonic germ cells is maintained until the adult stage, suggesting the implication of a cellular memory mechanism. Taken together, data presented here show that piRNAs and their associated proteins are epigenetic components of a continuous repression system throughout germ cell development. PMID:27932388

Production of otoconia in the endolymphatic sac in the Japanese red-bellied newt, Cynops pyrrhogaster: light and transmission electron microscopic study

NASA Technical Reports Server (NTRS)

Gao, W.; Wiederhold, M. L.; Hejl, R.

1998-01-01

The formation of otoconia in the endolymphatic sac (ES) of the larval newt, Cynops pyrrhogaster, has been studied by light and transmission electron microscopy. Some of the epithelial cells of the ES contain an abundance of swollen vesicles, Golgi complexes, rough endoplasmic reticula and ribosomes at the late larval stages 50 and 51, approximately 26-30 days after eggs are laid. Five days later, at stage 52, crystals are present in the vacuoles between the epithelial cells. Serial sections indicate that these vacuoles actually form small canals which lie in the wall and join the lumen of the ES. Reconstruction of the ES shows that several canals are contained in the ES wall. At stage 56, about 72 days after eggs are laid, a large number of otoconia are present in the ES lumen, while the otoconia disappear from the canals. It appears that the otoconia are first produced in the canals and then released to the lumen. Some epithelial cells of the ES are thought to expel the organic and inorganic material to the canals to form the otoconia in situ. The process of formation of the otoconia in the ES is discussed.

A Presynaptic Regulatory System Acts Transsynaptically via Mon1 to Regulate Glutamate Receptor Levels in Drosophila.

PubMed

Deivasigamani, Senthilkumar; Basargekar, Anagha; Shweta, Kumari; Sonavane, Pooja; Ratnaparkhi, Girish S; Ratnaparkhi, Anuradha

2015-10-01

Mon1 is an evolutionarily conserved protein involved in the conversion of Rab5 positive early endosomes to late endosomes through the recruitment of Rab7. We have identified a role for Drosophila Mon1 in regulating glutamate receptor levels at the larval neuromuscular junction. We generated mutants in Dmon1 through P-element excision. These mutants are short-lived with strong motor defects. At the synapse, the mutants show altered bouton morphology with several small supernumerary or satellite boutons surrounding a mature bouton; a significant increase in expression of GluRIIA and reduced expression of Bruchpilot. Neuronal knockdown of Dmon1 is sufficient to increase GluRIIA levels, suggesting its involvement in a presynaptic mechanism that regulates postsynaptic receptor levels. Ultrastructural analysis of mutant synapses reveals significantly smaller synaptic vesicles. Overexpression of vglut suppresses the defects in synaptic morphology and also downregulates GluRIIA levels in Dmon1 mutants, suggesting that homeostatic mechanisms are not affected in these mutants. We propose that DMon1 is part of a presynaptically regulated transsynaptic mechanism that regulates GluRIIA levels at the larval neuromuscular junction. Copyright © 2015 by the Genetics Society of America.

Postharvest irradiation treatment for quarantine control of Drosophila suzukii (Diptera: Drosophilidae) in fresh commodities.

PubMed

Follett, Peter A; Swedman, Allison; Prices, Donald K

2014-06-01

Irradiation is a postharvest quarantine treatment option for exported commodities such as stone fruits and small fruits to prevent movement of the new invasive pest spotted wing drosophila, Drosophila suzukii (Walker) (Diptera: Drosophilidae). The effects of irradiation on larval and pupal development and adult reproduction in D. suzukii were examined. Larvae (first, second, and third instars) and pupae (1-2-d-old, 3-5-d-old, and 7-8-d-old) on diet were irradiated at target doses of 20, 30, 40, and 50 Gy in replicated factorial experiments and survival to the adult stage was recorded. Tolerance to radiation increased with increasing age and developmental stage. Males and females were equally susceptible. A radiation dose of 40 Gy applied to first- and second-instar larvae prevented adult emergence. The late-stage pupa was the most radiation-tolerant stage that occurs in fruit, and individuals irradiated at this stage readily emerged as adults; therefore, prevention of F1 adults was the desired treatment response for large-scale validation tests with naturally infested fruit. In large-scale tests, a radiation dose of 80 Gy applied to late-stage pupae in sweet cherries or grapes resulted in no production of F1 adults in > 33,000 treated individuals, which meets the zero tolerance requirement for market access. A minimum absorbed dose of 80 Gy is recommended for quarantine control of D. suzukii.

Seasonal variations in the gastro-intestinal nematode populations of Scottish hil sheep.

PubMed

Reid, J F; Armour, J

1975-05-01

In each of two consecutive years, groups of breeding ewes were removed from a hill farm in the west of Scotland on four occasions, namely late pregnancy, early lactation, autumn and early winter. At slaughter the major nematode genus present in the alimentary tract was Ostertagia, with O circumcincta the predominant species but three species previously found in Scottish hill sheep, Bunostomum trigonocephalum, Strongyloides papillosis and Chabertia ovina were absent. An absolute increase in total nematode burden and faecal egg count was apparent in the ewes commencing in late pregnancy, reaching a maximum during lactation and falling again in autumn and early winter. This peri-parturient increase in the nematode population could not be solely attributed to the maturation of previously inhibited larval stages but was primarily the result of the development of recently ingested infection; the latter situation thought to be due to a temporary relaxation of immunological response by the ewe at parturition or early lactation. Serum pepsinogen values in ewes remained elevated throughout the grazing season and were always higher than those of their lambs, suggesting that the ewe, although allowing few parasites to become established, was under considerable challenge in the autumn. The worm burdens of the lambs were always low in autumn and early winter with Ostertagia spp being the major genus present during the autumn and Trichostrongylus spp being the predominant genus during the early winter.

Distribution and condition of larval and juvenile Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon

USGS Publications Warehouse

Burdick, Summer M.; Brown, Daniel T.

2010-01-01

Federally endangered Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were once abundant throughout their range but populations have declined. They were extirpated from several lakes in the 1920s and may no longer reproduce in others. Poor recruitment to the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable or high quality rearing habitat. In addition, larval suckers may be swept downstream from suitable rearing areas in Upper Klamath Lake into Keno Reservoir, which is seasonally anoxic. The Nature Conservancy flooded about 3,600 acres (1,456 hectares) to the north of the Williamson River mouth (Tulana Unit) in October 2007 and about 1,400 acres (567 hectares) to the south and east of the Williamson River mouth (Goose Bay Unit) a year later to retain larval suckers in Upper Klamath Lake, create nursery habitat, and improve water quality. The U.S. Geological Survey joined a long-term research and monitoring program in collaboration with The Nature Conservancy, the Bureau of Reclamation, and Oregon State University in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. The primary objectives of the research were to describe habitat colonization and use by larval and juvenile suckers and non-sucker fishes and to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report summarizes data collected in 2009 by the U.S. Geological Survey as a part of this monitoring effort. The Williamson River Delta appeared to provide suitable rearing habitat for endangered larval Lost River and shortnose suckers in 2008 and 2009. Larval suckers captured in this delta typically were larger than those captured in the adjacent lake habitat in 2008, but the opposite was true for larval shortnose suckers in 2009. Mean sample density was greater for both species in the Williamson River Delta than adjacent lake habitats in both years. Larval suckers captured in the restoration area, however, had less food in their guts compared to those captured in Upper Klamath or Agency Lakes. Differential distribution among sucker species within the Williamson River Delta and between the delta and adjacent lakes indicated that shortnose suckers likely benefited more from the restored Williamson River Delta than Lost River or Klamath largescale suckers (Catostomus snyderi). Catch rates in shallow-water habitats with vegetation within the delta were higher for shortnose and Klamath largescale suckers than for larval Lost River suckers in 2008 and 2009.However, catch rates at the mouth of the Williamson River in 2008 and in Upper Klamath Lake in 2009 were higher for larval Lost River suckers than for larvae identified as either shortnose or Klamath largescale suckers. Shortnose suckers also comprised the greatest portion of age-0 suckers captured in the Williamson River Delta in 2008 and 2009. The relative abundance of age-1 shortnose suckers was high in our catches compared to age-1 Lost River suckers in 2009 in the delta and adjacent lakes, which may or may not indicate shortnose suckers experienced better survival than Lost River suckers in 2008. Age-0 and age-1 suckers were similarly distributed throughout the Williamson River Delta in 2008 and 2009. Age-0 suckers used shallow vegetated and unvegetated habitats primarily in mid- to late July in both years. A comparison of catch rates between our study and a concurrent study in Upper Klamath Lake indicated that Goose Bay was the most used habitat in 2009 and the Tulana Unit was the one of the least used habitats in 2008 and 2009 by age-0 suckers. Catch rates for age-1 suckers, however, indicated that bo

Grass Pollen Affects Survival and Development of Larval Anopheles arabiensis (Diptera: Culicidae).

PubMed

Asmare, Yelfwagash; Hopkins, Richard J; Tekie, Habte; Hill, Sharon R; Ignell, Rickard

2017-09-01

Nutrients in breeding sites are critical for the survival and development of malaria mosquitoes, having a direct impact on vectorial capacity. Yet, there is a limited understanding about the natural larval diet and its impact on the individual fitness of mosquitoes. Recent studies have shown that gravid Anopheles arabiensis Patton (Diptera: Culicidae) are attracted by and oviposit in grass-associated habitats. The pollen provided by these grasses is a potential source of nutrients for the larvae. Here, we assess the effect of Typha latifolia L. (Poales: Typhaceae), Echinochloa pyramidalis Lamarck, Pennisetum setaceum Forsskål, and Zea mays L. pollen on larval survival and rate of development in An. arabiensis under laboratory conditions. In addition, we characterize the carbon to nitrogen ratio and the size of pollen grains as a measure of diet quality. Carbon-rich pollen with a small grain size (T. latifolia and P. setaceum; 9.7 ± 0.3 × 103 and 5.5 ± 0.2 × 104 µm3, respectively) resulted in enhanced rates of development of An. arabiensis. In contrast, the larva fed on the nitrogen-rich control diet (TetraMin) was slower to develop, but demonstrated the highest larval survival. Larvae fed on carbon-rich and large-grained Z. mays pollen (4.1 ± 0.2 × 105 µm3) survived at similar levels as those fed on the control diet and also took a longer time to develop compared with larvae fed on the other pollens. While males and females did not appear to develop differently on the different pollen diets, males consistently emerged faster than their female counterparts. These results are discussed in relation to integrated vector management. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America.

Synchronism of naupliar development of Sacculina carcini Thompson, 1836 (Pancrustacea, Rhizocephala) revealed by precise monitoring

NASA Astrophysics Data System (ADS)

Trédez, Fabien; Rabet, Nicolas; Bellec, Laure; Audebert, Fabienne

2017-01-01

Sacculina carcini is member of a highly-specialized group of parasitic cirripeds (Rhizocephala) that use crabs ( Carcinus maenas) as hosts to carry out the reproductive phase of their life cycle. We describe the naupliar development of S. carcini Thompson, 1836 from a very precise monitoring of three different broods from three specimens. Nauplii were sampled every 4 h, from the release of the larvae until the cypris stage. Larval development, from naupliar instar 1 to the cypris stage, lasts 108 h at 18 °C. A rigorous sampling allowed us to describe an additional intermediate naupliar instar, not described previously. Naupliar instars are renumbered from 1 to 5. Nauplius 1 (N1) larvae hatch in the interna; N2 are released from the interna and last between 12 and 16 h; N3 appear between 12 and 16 h after release; N4 appear between 28 and 32 h; and N5 appear between 44 and 48 h. The cypris stage appears between 108 and 112 h. The redescribed morphologies allowed us to identify new characters. Antennular setation discriminates naupliar instars 3, 4 and 5. Telson and furca morphologies discriminate all naupliar instars. Furthermore, we demonstrate that the speed of larval development is similar within a single brood and between broods from different specimens, suggesting synchronization of larval development. From precise monitoring of broods every 4 h, we demonstrate that the life cycle of S. carcini includes five instars of naupliar larvae instead of four. The morphological characters of the larvae discriminate these naupliar instars and allow the identification of S. carcini from other Rhizocephala species. S. carcini larvae develop synchronously. Consequently, they might be an informative model to study larval development in crustaceans.

Effects of temperature on the embryonic and early larval development in tropical species of black sea urchin, Diadema setosum (Leske, 1778).

PubMed

Sarifudin, M; Rahman, M A; Yusoff, F M; Arshad, Aziz; Tan, Soon Guan

2016-07-01

Influence of temperature on the embryonic and early development and growth performance of larva in tropical sea urchin, Diadema setosum was investigated in water temperature ranging between 16 and 34?C under controlled laboratory conditions. The critical lower and higher temperature for embryonic development was found at 16 and 34?C, respectively. Embryos reared in both of these two temperatures exhibited 100% abnormality within 48 hrs post-insemination. The time required to reach these embryonic and larval stages increased with temperature from 28 followed by 31, 25, 22 and 19?C in that order. The developmental times of 2-cell stage until 4-arm pluteus larva showed significant differences (P < 0.05) among the tested temperatures. The larvae in the state of prism and 2-arm pluteus, survived at temperature ranging from 19 to 31?C, while the 4-arm pluteus larvae survived at temperature between 22? to 31?C. However, larval development within a temperature range of 22? to 31?C was acceptable since no abnormalities occurred. The morphometric characteristics from prism to 4-arm pluteus larvae in all the temperatures differed significantly (P > 0.05). Among them, 28?C was found to be the best temperature with respect of the highest larval growth and development at all stages. The findings of the study will not only be helpful to understand the critical limits of temperature, but also to identify the most appropriate temperature for optimum growth and development of embryos and larvae, as well as to facilitate the development of captive breeding and mass seed production of D. setosum and other important sea urchins for commercial aquaculture.

Yolk-sac larval development of the substrate-brooding cichlid Archocentrus nigrofasciatus in relation to temperature.

PubMed

Vlahos, Nikolaos; Vasilopoulos, Michael; Mente, Eleni; Hotos, George; Katselis, George; Vidalis, Kosmas

2015-09-01

In order to conserve and culture the cichlid fish Archocentrus nigrofasciatus, more information about its reproductive biology and its larval behavior and morphogenesis is necessary. Currently, temperatures ranging from 21 to 27 °C are used in ornamental aquaculture hatcheries. Lower temperatures are preferred to reduce the costs of water heating, and 23 °C is usually the selected temperature. However, there is limited information on culturing protocols for ornamental species and most of the information generated on this topic remains scarce. Thus, the present study examines the morphological development of Archocentrus nigrofasciatus during the yolk-sac period up to the age of 100 h post-hatching in relation to 2 temperature regimes used in ornamental aquaculture: a temperature of 27 °C (thermal optimum) and a decreased temperature of 23 °C (thermal tolerance). The results of this study suggest that the 27 °C temperature generates intense morphological changes in yolk-sac development in a shorter period. This has advantages as it reduces the time of yolk-sac larval development, and, thus, minimizes the transition phase to exogenous feeding and maximizes the efficiency at which yolk is converted into body tissues. The present paper provides necessary information to produce freshwater ornamental fish with better practices so as to increase larval survival and capitalize on time for growth. © 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Morphology and metamorphosis of Eupsophus calcaratus tadpoles (Anura: Leptodactylidae).

PubMed

Vera Candioti, M F; Ubeda, C; Lavilla, E O

2005-05-01

Eupsophus calcaratus, a leptodactyloid frog from the austral Andean forests of Argentina and Chile, has endotrophic, nidicolous tadpoles. We studied a metamorphic series from Stages 31 to 46 of Gosner's developmental table (1960). Other than the scarce pigmentation, proportionately large eyes, and massive developing hindlimbs, the remaining external characters are similar to those of generalized, exotrophic larvae. At the same time, internal morphology does not reveal any character state attributable to the endotrophic-nidicolous way of life; conversely, structures such as the hyobranchial skeleton and the mandibular cartilages are similar to those of exotrophic-macrophagous tadpoles. The metamorphic process is characterized by the delayed development of diverse structures (e.g., ethmoid region, palatoquadrate, and hyobranchial apparatus), and the retention of some larval characters (e.g., parietal fenestrae, overall absence of ossification) with the absence of development of some "juvenile" characters (e.g., adult otic process, several bones) in metamorphosed individuals. These heterochronic processes and truncation of larval development are related to a shorter larval life (when compared to other species of the austral Andean region) and to the small size at metamorphosis. 2004 Wiley-Liss, Inc.

Cemetery vase breeding of dengue vectors in Manila, Republic of the Philippines.

PubMed

Schultz, G W

1989-12-01

Aedes albopictus and Ae. aegypti were found breeding abundantly in cement vases within cemeteries in Manila. Aedes albopictus dominated in cemeteries containing vegetation which provided both shade and plant debris for the vase water. The highest larval densities for both species were found from August to December, which is from mid-to-late rainy season. Aedes albopictus is unable to compete successfully with Ae. aegypti in residential areas with sparce vegetation and thus is very limited in its distribution within the city. Biting activity of both species is similar, with peaks occurring between 0530-0600 h and 1730-1800 h.

On-Plant Larval Movement and Feeding Behavior of Fall Armyworm (Lepidoptera: Noctuidae) on Reproductive Corn Stages.

PubMed

Pannuti, L E R; Baldin, E L L; Hunt, T E; Paula-Moraes, S V

2016-02-01

Spodoptera frugiperda J.E. Smith (fall armyworm) is considered one of the most destructive pests of corn throughout the Americas. Although this pest has been extensively studied, little is known about its larval movement and feeding behavior on reproductive compared to vegetative corn stages. Thus, we conducted studies with two corn stages (R1 and R3) and four corn plant zones (tassel, above ear, ear zone, and below ear) in the field at Concord, NE (USA), and in the field and greenhouse at Botucatu, SP (Brazil), to investigate on-plant larval movement. The effects of different corn tissues (opened tassel, closed tassel, silk, kernel, and leaf), two feeding sequence scenarios (closed tassel-leaf-silk-kernel and leaf-silk-kernel), and artificial diet (positive control) on larval survival and development were also evaluated in the laboratory. Ear zone has a strong effect on feeding choice and survival of fall armyworm larvae regardless of reproductive corn stage. Feeding site choice is made by first-instar. Corn leaves of reproductive plants were not suitable for early instar development, but silk and kernel tissues had a positive effect on survival and development of fall armyworm larvae on reproductive stage corn. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Testing the effect of dietary carotenoids on larval survival, growth and development in the critically endangered southern corroboree frog.

PubMed

Byrne, Phillip G; Silla, Aimee J

2017-03-01

The success of captive breeding programs (CBPs) for threatened species is often limited due to a lack of knowledge of the nutritional conditions required for optimal growth and survival. Carotenoids are powerful antioxidants known to accelerate vertebrate growth and reduce mortality. However, the effect of carotenoids on amphibian life-history traits remains poorly understood. The aim of our study was to use a manipulative laboratory experiment to test the effect of dietary-carotenoid supplementation during the larval life stage on the survival, growth and development of the critically endangered southern corroboree frog (Pseudophryne corroboree). Larvae were fed either a carotenoid supplemented diet or an unsupplemented diet and the survival, growth and development of individuals was monitored and compared. There was no significant effect of dietary treatment on larval survival, growth rate, time taken to reach metamorphosis, or body size at metamorphosis. Our findings provide no evidence that carotenoid supplementation during the larval life stage improves the growth and development of southern corroboree frogs. However, because the carotenoid dose used in our study did not have any detrimental effects on P. corroboree larvae, but has previously been shown to improve adult coloration, immunity, and exercise performance, carotenoid supplementation should be considered when evaluating the nutritional requirements of P. corroboree in captivity. Carotenoid supplementation studies are now required for a diversity of anuran species to determine the effects of carotenoids on amphibian survival, growth and development. Understanding the effects of dietary carotenoids on different life-history traits may assist with amphibian captive breeding and conservation. © 2017 Wiley Periodicals, Inc.

Postnatal brain development of the pulse type, weakly electric gymnotid fish Gymnotus omarorum.

PubMed

Iribarne, Leticia; Castelló, María E

2014-01-01

Teleosts are a numerous and diverse group of fish showing great variation in body shape, ecological niches and behaviors, and a correspondent diversity in brain morphology, usually associated with their functional specialization. Weakly electric fish are a paradigmatic example of functional specialization, as these teleosts use self-generated electric fields to sense the nearby environment and communicate with conspecifics, enabling fish to better exploit particular ecological niches. We analyzed the development of the brain of the pulse type gymnotid Gymnotus omarorum, focusing on the brain regions involved directly or indirectly in electrosensory information processing. A morphometric analysis has been made of the whole brain and of brain regions of interest, based on volumetric data obtained from 3-D reconstructions to study the growth of the whole brain and the relative growth of brain regions, from late larvae to adulthood. In the smallest studied larvae some components of the electrosensory pathway appeared to be already organized and functional, as evidenced by tract-tracing and in vivo field potential recordings of electrosensory-evoked activity. From late larval to adult stages, rombencephalic brain regions (cerebellum and electrosensory lateral line lobe) showed a positive allometric growth, mesencephalic brain regions showed a negative allometric growth, and the telencephalon showed an isometric growth. In a first step towards elucidating the role of cell proliferation in the relative growth of the analyzed brain regions, we also studied the spatial distribution of proliferation zones by means of pulse type BrdU labeling revealed by immunohistochemistry. The brain of G. omarorum late larvae showed a widespread distribution of proliferating zones, most of which were located at the ventricular-cisternal lining. Interestingly, we also found extra ventricular-cisternal proliferation zones at in the rombencephalic cerebellum and electrosensory lateral line lobe. We discuss the role of extraventricular-cisternal proliferation in the relative growth of the latter brain regions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Testing lagoonal sediments with early life stages of the copepod Acartia tonsa (Dana): An approach to assess sediment toxicity in the Venice Lagoon.

PubMed

Picone, Marco; Bergamin, Martina; Delaney, Eugenia; Ghirardini, Annamaria Volpi; Kusk, Kresten Ole

2018-01-01

The early-life stages of development of the calanoid copepod Acartia tonsa from egg to copepodite I is proposed as an endpoint for assessing sediment toxicity by exposing newly released eggs directly onto the sediment-water interface. A preliminary study of 5 sediment samples collected in the lagoon of Venice highlighted that the larval development rate (LDR) and the early-life stages (ELS) mortality endpoints with A. tonsa are more sensitive than the standard amphipod mortality test; moreover LDR resulted in a more reliable endpoint than ELS mortality, due to the interference of the sediment with the recovery of unhatched eggs and dead larvae. The LDR data collected in a definitive study of 48 sediment samples from the Venice Lagoon has been analysed together with the preliminary data to evaluate the statistical performances of the bioassay (among replicate variance and minimum significant difference between samples and control) and to investigate the possible correlation with sediment chemistry and physical properties. The results showed that statistical performances of the LDR test with A. tonsa correspond with the outcomes of other tests applied to the sediment-water interface (Strongylocentrotus purpuratus embryotoxicity test), sediments (Neanthes arenaceodentata survival and growth test) and porewater (S. purpuratus); the LDR endpoint did, however, show a slightly higher variance as compared with other tests used in the Lagoon of Venice, such as 10-d amphipod lethality test and larval development with sea urchin and bivalves embryos. Sediment toxicity data highlighted the high sensitivity and the clear ability of the larval development to discriminate among sediments characterized by different levels of contamination. The data of the definitive study evidenced that inhibition of the larval development was not affected by grain-size and the organic carbon content of the sediment; in contrast, a strong correlation between inhibition of the larval development and the sediment concentrations of some metals (Cu, Hg, Pb, Zn), acid-volatile sulphides (AVS), polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs) was found. No correlation was found with DDTs, hexachlorobenzene and organotin compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

Seasonal Phenology and Life-History of Dendroctonus simplex (Coleoptera: Curculionidae) in the Great Lakes Region of North America.

PubMed

McKee, Fraser R; Aukema, Brian H

2016-08-01

The eastern larch beetle, Dendroctonus simplex LeConte (Coleoptera: Curculionidae), is distributed throughout the North American boreal forest sympatric with its primary host, the eastern larch or tamarack, Larix laricina (Du Roi) K. Koch. Outbreaks of eastern larch beetles are typically small and associated with stressed tamaracks. Since 2000, however, an outbreak has killed >90,000 ha of tamarack in Minnesota and surrounding Great Lakes region. Identifying the causes of this epidemic is challenging due to knowledge gaps regarding the insect's biology. We present field data from 2011 to 2014 on degree days associated with spring emergence, dispersal, host colonization, and re-emergence from colonized hosts by mature adult beetles, as well as degree days associated with larval development, and prewinter emergence by adult progeny at study sites in northern Minnesota. After initial host colonization in early spring we found that a second brood was established in early summer by re-emerging parents. In 2012, a third brood was established. Across study years, first broods developed to adults by late summer, with many beetles relocating to the base of the host tree to overwinter. Second broods often reached adulthood and initiated prewinter emergence. The third brood of 2012 overwintered as adults, pupae, and late-instars, resuming development the following spring. Each spring, emergence of adult beetles from all broods established the previous year was highly synchronous. Knowledge of the biology of eastern larch beetles along the southern margin of their range aids in understanding how population dynamics may change with a changing climate. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Stage-dependent and temperature-controlled expression of the gene encoding the precursor protein of diapause hormone and pheromone biosynthesis activating neuropeptide in the silkworm, Bombyx mori.

PubMed

Xu, W H; Sato, Y; Ikeda, M; Yamashita, O

1995-02-24

Embryonic diapause and sex pheromone biosynthesis in the silkworm, Bombyx mori, are, respectively, induced by diapause hormone (DH) and pheromone biosynthesis activating neuropeptide (PBAN), which are produced in the subesophageal ganglion from a common polyprotein precursor (DH-PBAN precursor) encoded by a single gene (DH-PBAN gene). Using DH-PBAN cDNA as a probe, we quantitatively measured DH-PBAN mRNA content throughout embryonic and postembryonic development and observed the effects of incubation temperature, which is a key factor for determination of diapause, on DH-PBAN gene expression. The silkworm, which is programmed to lay diapause eggs by being incubated at 25 degrees C, showed peaks of DH-PBAN mRNA content at five different stages throughout the life cycle: at the late embryonic stage, at the middle of the fourth and the fifth larval instars, and at early and late stages of pupal-adult development. In the non-diapause type silkworms programmed by a 15 degrees C incubation, only the last peak of DH-PBAN mRNA in pupal-adult development was found, and the other peaks were absent. Furthermore, interruption of the incubation period at 25 degrees C by incubation at 15 degrees C decreased both DH-PBAN mRNA content in mature embryos and in subesophageal ganglia of day 3 pupae and the incidence of diapause eggs. Thus, there were two types of regulatory mechanisms for DH-PBAN gene expression. One is a temperature-controlled expression that is responsible for diapause induction, and the other is a temperature-independent, stage-dependent expression related to pheromone production.

Establishment of a medium-scale mosquito facility: optimization of the larval mass-rearing unit for Aedes albopictus (Diptera: Culicidae).

PubMed

Zhang, Dongjing; Zhang, Meichun; Wu, Yu; Gilles, Jeremie R L; Yamada, Hanano; Wu, Zhongdao; Xi, Zhiyong; Zheng, Xiaoying

2017-11-13

Standardized larval rearing units for mosquito production are essential for the establishment of a mass-rearing facility. Two larval rearing units, developed respectively by the Guangzhou Wolbaki Biotech Co. Ltd. (Wolbaki) and Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture (FAO/IAEA-IPCL), are tested to assess their potential uses to mass-rear the larval stages of Aedes albopictus in support of the establishment of a medium-scale mosquito facility for the application of mosquito genetic control strategies. The triple Wolbachia-infected Ae. albopictus strain (HC strain) was used in this study. The effects of larval densities of two larval rearing trays (corresponding to 2.4, 3.0 and 3.6 larvae/cm 2 ) and tray size/position (top, middle and bottom layers) on the pupae production and larval survival were assessed when trays were stacked within the larval rearing units. The male pupae production, female pupae contamination after sex separation, and male mating competitiveness were also studied by using both larval rearing units in their entirety. The optimal larval rearing density for Wolbaki-tray (Wol-tray) was 6,600 larvae (equal to 3.0 larvae/cm 2 ) and 18,000 larvae (3.6 larvae/cm 2 ) for the FAO/IAEA-IPCL tray (IAEA-tray). No significant difference in pupae production was observed when trays were stacked within top, middle or bottom layers for both units. At thirty-four hours after the first pupation, the average male pupae production was (0.89 × 10 5 ) for the Wol-unit and (3.16 × 10 5 ) for the IAEA-unit. No significant difference was observed in female pupae contamination between these two units. The HC males showed equal male mating competitiveness to wild type males for mating with wild type females in large cages, regardless of whether they were reared in the Wol-unit or IAEA-unit. The current study has indicated that both the Wol-unit and IAEA-unit are suitable for larvae mass-rearing for Ae. albopictus. However, the IAEA-unit, with higher male production and less space required compared to the Wol-unit, is recommended to be used in support of the establishment of a medium-sized mosquito facility.

Determination of antibacterial activity and minimum inhibitory concentration of larval extract of fly via resazurin-based turbidometric assay.

PubMed

Teh, Chien Huey; Nazni, Wasi Ahmad; Nurulhusna, Ab Hamid; Norazah, Ahmad; Lee, Han Lim

2017-02-16

Antimicrobial resistance is currently a major global issue. As the rate of emergence of antimicrobial resistance has superseded the rate of discovery and introduction of new effective drugs, the medical arsenal now is experiencing shortage of effective drugs to combat diseases, particularly against diseases caused by the dreadful multidrug-resistant strains, such as the methicillin-resistant Staphylococcus aureus (MRSA). The ability of fly larvae to thrive in septic habitats has prompted us to determine the antibacterial activity and minimum inhibitory concentrations (MICs) of larval extract of flies, namely Lucilia cuprina, Sarcophaga peregrina and Musca domestica against 4 pathogenic bacteria [Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Pseudomonas aeruginosa and Escherichia coli] via a simple and sensitive antibacterial assay, resazurin-based turbidometric (TB) assay as well as to demonstrate the preliminary chemical profile of larval extracts using gas chromatography-mass spectrophotometry (GC-MS). The resazurin-based TB assay demonstrated that the L. cuprina larval extract was inhibitory against all tested bacteria, whilst the larval extract of S. peregrina and M. domestica were only inhibitory against the MRSA, with a MIC of 100 mg ml -1 . Subsequent sub-culture of aliquots revealed that the larval extract of L. cuprina was bactericidal against MRSA whilst the larval extracts of S. peregrina and M. domestica were bacteriostatic against MRSA. The GC-MS analysis had quantitatively identified 20 organic compounds (fatty acids or their derivatives, aromatic acid esters, glycosides and phenol) from the larval extract of L. cuprina; and 5 fatty acid derivatives with known antimicrobial activities from S. peregrina and M. domestica. The resazurin-based turbidometric assay is a simple, reliable and feasible screening assay which evidently demonstrated the antibacterial activity of all fly larval extracts, primarily against the MRSA. The larval extract of L. cuprina exerted a broad spectrum antibacterial activity against all tested bacteria. The present study revealed probable development and use of novel and effective natural disinfectant(s) and antibacterial agent(s) from flies and efforts to screen more fly species for antibacterial activity using resazurin-based TB assay should be undertaken for initial screening for subsequent discovery and isolation of potential novel antimicrobial substances, particularly against the multi-drug resistant strains.

Measuring larval nematode contamination on cattle pastures: Comparing two herbage sampling methods.

PubMed

Verschave, S H; Levecke, B; Duchateau, L; Vercruysse, J; Charlier, J

2015-06-15

Assessing levels of pasture larval contamination is frequently used to study the population dynamics of the free-living stages of parasitic nematodes of livestock. Direct quantification of infective larvae (L3) on herbage is the most applied method to measure pasture larval contamination. However, herbage collection remains labour intensive and there is a lack of studies addressing the variation induced by the sampling method and the required sample size. The aim of this study was (1) to compare two different sampling methods in terms of pasture larval count results and time required to sample, (2) to assess the amount of variation in larval counts at the level of sample plot, pasture and season, respectively and (3) to calculate the required sample size to assess pasture larval contamination with a predefined precision using random plots across pasture. Eight young stock pastures of different commercial dairy herds were sampled in three consecutive seasons during the grazing season (spring, summer and autumn). On each pasture, herbage samples were collected through both a double-crossed W-transect with samples taken every 10 steps (method 1) and four random located plots of 0.16 m(2) with collection of all herbage within the plot (method 2). The average (± standard deviation (SD)) pasture larval contamination using sampling methods 1 and 2 was 325 (± 479) and 305 (± 444)L3/kg dry herbage (DH), respectively. Large discrepancies in pasture larval counts of the same pasture and season were often seen between methods, but no significant difference (P = 0.38) in larval counts between methods was found. Less time was required to collect samples with method 2. This difference in collection time between methods was most pronounced for pastures with a surface area larger than 1 ha. The variation in pasture larval counts from samples generated by random plot sampling was mainly due to the repeated measurements on the same pasture in the same season (residual variance component = 6.2), rather than due to pasture (variance component = 0.55) or season (variance component = 0.15). Using the observed distribution of L3, the required sample size (i.e. number of plots per pasture) for sampling a pasture through random plots with a particular precision was simulated. A higher relative precision was acquired when estimating PLC on pastures with a high larval contamination and a low level of aggregation compared to pastures with a low larval contamination when the same sample size was applied. In the future, herbage sampling through random plots across pasture (method 2) seems a promising method to develop further as no significant difference in counts between the methods was found and this method was less time consuming. Copyright © 2015 Elsevier B.V. All rights reserved.

Allometric shell growth in infaunal burrowing bivalves: examples of the archiheterodonts Claibornicardia paleopatagonica (Ihering, 1903) and Crassatella kokeni Ihering, 1899.

PubMed

Perez, Damián Eduardo; Santelli, María Belén

2018-01-01

We present two cases of study of ontogenetic allometry in outlines of bivalves using longitudinal data, a rarity among fossils, based on the preserved post-larval record of shells. The examples are two infaunal burrowing bivalves of the southern South America, Claibornicardia paleopatagonica (Archiheterodonta: Carditidae) (early Paleocene) and Crassatella kokeni (Archiheterodonta: Crassatellidae) (late Oligocene-late Miocene). Outline analyses were conducted using a geometric morphometric approach (Elliptic Fourier Analysis), obtaining successive outlines from shells' growth lines, which were used to reconstruct ontogenetic trajectories. In both taxa, ontogenetic changes are characterized by the presence of positive allometry in the extension of posterior end, resulting in elongated adult shells. This particular allometric growth is known in others infaunal burrowing bivalves ( Claibornicardia alticostata and some Spissatella species) and the resulting adult morphology is present in representatives of several groups (e.g., Carditidae, Crassatellidae, Veneridae, Trigoniidae). Taxonomic, ecological and evolutionary implications of this allometric growth pattern are discussed.

Vulnerability of the calcifying larval stage of the Antarctic sea urchin Sterechinus neumayeri to near-future ocean acidification and warming.

PubMed

Byrne, Maria; Ho, Melanie A; Koleits, Lucas; Price, Casandra; King, Catherine K; Virtue, Patti; Tilbrook, Bronte; Lamare, Miles

2013-07-01

Stenothermal polar benthic marine invertebrates are highly sensitive to environmental perturbations but little is known about potential synergistic effects of concurrent ocean warming and acidification on development of their embryos and larvae. We examined the effects of these stressors on development to the calcifying larval stage in the Antarctic sea urchin Sterechinus neumayeri in embryos reared in present and future (2100+) ocean conditions from fertilization. Embryos were reared in 2 temperature (ambient: -1.0 °C, + 2 °C : 1.0 °C) and 3 pH (ambient: pH 8.0, -0.2-0.4 pH units: 7.8,7.6) levels. Principle coordinates analysis on five larval metrics showed a significant effect of temperature and pH on the pattern of growth. Within each temperature, larvae were separated by pH treatment, a pattern primarily influenced by larval arm and body length. Growth was accelerated by temperature with a 20-28% increase in postoral (PO) length at +2 °C across all pH levels. Growth was strongly depressed by reduced pH with a 8-19% decrease in PO length at pH 7.6-7.8 at both temperatures. The boost in growth caused by warming resulted in larvae that were larger than would be observed if acidification was examined in the absence of warming. However, there was no significant interaction between these stressors. The increase in left-right asymmetry and altered body allometry indicated that decreased pH disrupted developmental patterning and acted as a teratogen (agent causing developmental malformation). Decreased developmental success with just a 2 °C warming indicates that development in S. neumayeri is particularly sensitive to increased temperature. Increased temperature also altered larval allometry. Altered body shape impairs swimming and feeding in echinoplutei. In the absence of adaptation, it appears that the larval phase may be a bottleneck for survivorship of S. neumayeri in a changing ocean in a location where poleward migration to escape inhospitable conditions is not possible. © 2013 Blackwell Publishing Ltd.

The effect of larval nutritional deprivation on the life history and DDT resistance phenotype in laboratory strains of the malaria vector Anopheles arabiensis

PubMed Central

2013-01-01

Background Anopheles arabiensis is a major malaria vector in Africa. It thrives in agricultural areas and has been associated with increased malaria incidence in areas under rice and maize cultivation. This effect may be due to increased adult size and abundance as a consequence of optimal larval nutrition. The aim of this study was to examine the effect of larval nutrition on the life history and expression of insecticide resistance in adults of laboratory reared An. arabiensis. Methods Larvae drawn from an insecticide susceptible An. arabiensis strain (SENN) as well as a DDT-resistant strain (SENN-DDT) were subjected to three fasting regimes: 1 mg of food per larva offered once per day, once every second day and once every third day. Control cohorts included larvae offered 1 mg food thrice per day. The rate of larval development was compared between matched cohorts from each strain as well as between fasted larvae and their respective controls. The expression of DDT resistance/tolerance in adults was compared between the starved cohorts and their controls by strain. Factors potentially affecting variation in DDT resistance/tolerance were examined including: adult body size (wing length), knock-down resistance (kdr) status and levels of detoxification enzyme activity. Results and conclusion Anopheles arabiensis larval development is prolonged by nutrient deprivation and adults that eclose from starved larvae are smaller and less tolerant to DDT intoxication. This effect on DDT tolerance in adults is also associated with reduced detoxification enzyme activity. Conversely, well fed larvae develop comparatively quickly into large, more DDT tolerant (SENN) or resistant (SENN-DDT) adults. This is important in those instances where cereal farming is associated with increased An. arabiensis transmitted malaria incidence, because large adult females with high teneral reserves and decreased susceptibility to insecticide intoxication may also prove to be more efficient malaria vectors. In general, larval nutrient deprivation in An. arabiensis has important implications for subsequent adults in terms of their size and relative insecticide susceptibility, which may in turn impact on their malaria vector capacity in areas where insecticide based control measures are in place. PMID:23368928

Embryonic and post-embryonic development of the polyclad flatworm Maritigrella crozieri; implications for the evolution of spiralian life history traits

PubMed Central

2010-01-01

Background Planktonic life history stages of spiralians share some muscular, nervous and ciliary system characters in common. The distribution of these characters is patchy and can be interpreted either as the result of convergent evolution, or as the retention of primitive spiralian larval features. To understand the evolution of these characters adequate taxon sampling across the Spiralia is necessary. Polyclad flatworms are the only free-living Platyhelminthes that exhibit a continuum of developmental modes, with direct development at one extreme, and indirect development via a trochophore-like larval stage at the other. Here I present embryological and larval anatomical data from the indirect developing polyclad Maritrigrella crozieri, and consider these data within a comparative spiralian context. Results After 196 h hours of embryonic development, M. crozieri hatches as a swimming, planktotrophic larva. Larval myoanatomy consists of an orthogonal grid of circular and longitudinal body wall muscles plus parenchymal muscles. Diagonal body wall muscles develop over the planktonic period. Larval neuroanatomy consists of an apical plate, neuropile, paired nerve cords, a peri-oral nerve ring, a medial nerve, a ciliary band nerve net and putative ciliary photoreceptors. Apical neural elements develop first followed by posterior perikarya and later pharyngeal neural elements. The ciliated larva is encircled by a continuous, pre-oral band of longer cilia, which follows the distal margins of the lobes; it also possesses distinct apical and caudal cilia. Conclusions Within polyclads heterochronic shifts in the development of diagonal bodywall and pharyngeal muscles are correlated with life history strategies and feeding requirements. In contrast to many spiralians, M. crozieri hatch with well developed nervous and muscular systems. Comparisons of the ciliary bands and apical organs amongst spiralian planktonic life-stages reveal differences; M. crozieri lack a distinct ciliary band muscle and flask-shaped epidermal serotonergic cells of the apical organ. Based on current phylogenies, the distribution of ciliary bands and apical organs between polyclads and other spiralians is not congruent with a hypothesis of homology. However, some similarities exist, and this study sets an anatomical framework from which to investigate cellular and molecular mechanisms that will help to distinguish between parallelism, convergence and homology of these features. PMID:20426837

Viral nerve necrosis in hatchery-produced fry of Asian seabass Lates calcarifer: sequential microscopic analysis of histopathology.

PubMed

Azad, I S; Shekhar, M S; Thirunavukkarasu, A R; Jithendran, K P

2006-12-14

We studied the natural progression of viral nerve necrosis (VNN) in larvae of Asian seabass Lates calcarifer Bloch from 0 to 40 days post-hatch (dph). The hatchlings were reared in the vicinity of a confirmed nodavirus-affected older batch. Using light and electron microscopy (EM), we made a sequential analysis of histopathological manifestations in nerve tissue and other organs. There were no changes from the day of hatching until 4 dph. Larvae at 4 dph had viral particles in the intramuscular spaces underlying the skin, but the nerve cells of the brain were normal. The first signs of necrosis of the brain cells were observed at 6 dph. EM observations revealed characteristic membrane-bound viral particles measuring 30 nm in the cytoplasm of nerve cells of the brain, spinal cord and retina. Histological samples of fry examined when group mortalities reached 20 to 35% revealed highly vacuolated brains, empty nerve cell cytoplasm and viral particles in the intercellular spaces. Viral particles occurred extensively in the intramuscular spaces and the epidermal layers. These observations were corroborated by positive immunostaining of the virus-rich intramuscular spaces. EM studies also revealed progressive necrotic changes in the cells harboring the virus. Results emphasize the need to maintain hygiene in the hatchery environment and to develop strategies for prevention of disease spread among cohabiting seabass and other susceptible fish larvae. Intramuscular localization of the nodavirus in both preclinical healthy-looking and post-clinical moribund larvae suggests that virus neutralization strategies during larval development could be effective in controlling VNN-associated mortalities.

Ontogenetic changes in responses to settlement cues by Anemonefish

NASA Astrophysics Data System (ADS)

Dixson, D. L.; Munday, P. L.; Pratchett, M.; Jones, G. P.

2011-12-01

Population connectivity for most marine species is dictated by dispersal during the pelagic larval stage. Although reef fish larvae are known to display behavioral adaptations that influence settlement site selection, little is known about the development of behavioral preferences throughout the larval phase. Whether larvae are attracted to the same sensory cues throughout their larval phase, or exhibit distinct ontogenetic shifts in sensory preference is unknown. Here, we demonstrate an ontogenetic shift in olfactory cue preferences for two species of anemonefish, a process that could aid in understanding both patterns of dispersal and settlement. Aquarium-bred naïve Amphiprion percula and A. melanopus larvae were tested for olfactory preference of relevant reef-associated chemical cues throughout the 11-day pelagic larval stage. Age posthatching had a significant effect on the preference for olfactory cues from host anemones and live corals for both species. Preferences of olfactory cues from tropical plants of A. percula, increased by approximately ninefold between hatching and settlement, with A. percula larvae showing a fivefold increase in preference for the olfactory cue produced by the grass species. Larval age had no effect on the olfactory preference for untreated seawater over the swamp-based tree Melaleuca nervosa, which was always avoided compared with blank seawater. These results indicate that reef fish larvae are capable of utilizing olfactory cues early in the larval stage and may be predisposed to disperse away from reefs, with innate olfactory preferences drawing newly hatched larvae into the pelagic environment. Toward the end of the larval phase, larvae become attracted to the olfactory cues of appropriate habitats, which may assist them in identification of and navigation toward suitable settlement sites.

Recruitment constraints in Singapore's fluted giant clam (Tridacna squamosa) population—A dispersal model approach

PubMed Central

Neo, Mei Lin; Erftemeijer, Paul L. A.; van Beek, Jan K. L.; van Maren, Dirk S.; Teo, Serena L-M.; Todd, Peter A.

2013-01-01

Recruitment constraints on Singapore's dwindling fluted giant clam, Tridacna squamosa, population were studied by modelling fertilisation, larval transport, and settlement using real-time hydrodynamic forcing combined with knowledge of spawning characteristics, larval development, behaviour, and settlement cues. Larval transport was simulated using a finite-volume advection-diffusion model coupled to a three-dimensional hydrodynamic model. Three recruitment constraint hypotheses were tested: 1) there is limited connectivity between Singapore's reefs and other reefs in the region, 2) there is limited exchange within Singapore's Southern Islands, and 3) there exist low-density constraints to fertilisation efficacy (component Allee effects). Results showed that connectivity among giant clam populations was primarily determined by residual hydrodynamic flows and spawning time, with greatest chances of successful settlement occurring when spawning and subsequent larval dispersal coincided with the period of lowest residual flow. Simulations suggested poor larval transport from reefs located along the Peninsular Malaysia to Singapore, probably due to strong surface currents between the Andaman Sea and South China Sea combined with a major land barrier disrupting larval movement among reefs. The model, however, predicted offshore coral reefs to the southeast of Singapore (Bintan and Batam) may represent a significant source of larvae. Larval exchange within Singapore's Southern Islands varied substantially depending on the locations of source and sink reefs as well as spawning time; but all simulations resulted in low settler densities (2.1–68.6 settled individuals per 10,000 m2). Poor fertilisation rates predicted by the model indicate that the low density and scattered distribution of the remaining T. squamosa in Singapore are likely to significantly inhibit any natural recovery of local stocks. PMID:23555597

The effect of canopy cover and seasonal change on host plant quality for the endangered Karner blue butterfly (Lycaeides melissa samuelis)

USGS Publications Warehouse

Grundel, Ralph; Pavlovic, Noel B.; Sulzman, Christina L.

1998-01-01

Larvae of the Karner blue butterfly, Lycaeides melissa samuelis, feed solely on wild lupine, Lupinus perennis, from the emergence to summer senescence of the plant. Wild lupine is most abundant in open areas but Karner blue females oviposit more frequently on lupines growing in moderate shade. Can differences in lupine quality between open and shaded areas help explain this disparity in resource use? Furthermore, many lupines are senescent before the second larval brood completes development. How does lupine senescence affect larval growth? We addressed these questions by measuring growth rates of larvae fed lupines of different phenological stages and lupines growing under different shade conditions. The habitat conditions under which lupines grew and plant phenological stage did not generally affect final larval or pupal weight but did significantly affect duration of the larval period. Duration was shortest for larvae fed leaves from flowering lupines and was negatively correlated with leaf nitrogen concentration. Ovipositing in areas of moderate shade should increase second-brood larval exposure to flowering lupines. In addition, larval growth was significantly faster on shade-grown lupines that were in seed than on similar sun-grown lupines. These are possible advantages of the higher-than-expected oviposition rate on shade-grown lupines. Given the canopy-related trade-off between lupine abundance and quality, maintenance of canopy heterogeneity is an important conservation management goal. Larvae were also fed leaves growing in poor soil conditions and leaves with mildew infection. These and other feeding treatments that we anticipated would inhibit larval growth often did not. In particular, ant-tended larvae exhibited the highest weight gain per amount of lupine eaten and a relatively fast growth rate. This represents an advantage of ant tending to Karner blue larvae.

Calcified aquatic insect larval constructions in the Pleistocene tufa of Jebel El Mida, Gafsa, southern Tunisia: Recognition and paleoenvironmental significance

NASA Astrophysics Data System (ADS)

Ben Ahmed, Walid; Henchiri, Mohsen; Mastouri, Amna; Slim S'himi, Najet

2018-04-01

Calcified aquatic larval cases were recognized and identified in the Pleistocene tufa masses of Jebel El Mida, Gafsa, southern Tunisia. These larval constructions belong to three main insect families: caddisflies (Trichoptera, Hydropsychidae), midges (Diptera, Chironomidae) and aquatic moths (Lepidoptera, Pyralidae) that inhabited tubes in the tufa and spun nets. Each insect community has its distinctive characteristics of larval constructions that allow their recognition. The larval constructions recognized comprise fixed and portable (for caddisflies) dwelling cases and silken retreats and feeding capture nets. These last-mentioned are almost completely eroded and only remnants are preserved. The spatial distribution of these larval cases within the tufa is not random but, rather imposed by some specific paleohydraulic conditions. It's the reason why aquatic insect larval constructions are considered as prominent tool for the reconstruction of tufa and travertine depositional environments. Chironomid fixed dwelling cases (diameters range from 0.6 mm for clustered tubes to 3 mm) indicate the deposition of tufa under lotic (flowing) or lentic (standing) water conditions. The later hydraulic condition is shared with hydropsychids with fixed retreats (0.2-4 mm in diameter). Portable case-building caddisflies (case length ranging from 5 to 20 mm, and diameter from 3 to 5 mm at the cephalic end) prefer lentic conditions and are almost completely missing in high-energy flowing water locations that are preferred by pyralids (tubes are between 5 and 10 mm long and 3 mm in diameter). These insect families benefit from inhabiting the tufa by the availability of construction materials of their cases and the necessary space for their development.

Consequences of Food Restriction for Immune Defense, Parasite Infection, and Fitness in Monarch Butterflies.

PubMed

McKay, Alexa Fritzsche; Ezenwa, Vanessa O; Altizer, Sonia

2016-01-01

Organisms have a finite pool of resources to allocate toward multiple competing needs, such as development, reproduction, and enemy defense. Abundant resources can support investment in multiple traits simultaneously, but limited resources might promote trade-offs between fitness-related traits and immune defenses. We asked how food restriction at both larval and adult life stages of the monarch butterfly (Danaus plexippus) affected measures of immunity, fitness, and immune-fitness interactions. We experimentally infected a subset of monarchs with a specialist protozoan parasite to determine whether parasitism further affected these relationships and whether food restriction influenced the outcome of infection. Larval food restriction reduced monarch fitness measures both within the same life stage (e.g., pupal mass) as well as later in life (e.g., adult lifespan); adult food restriction further reduced adult lifespan. Larval food restriction lowered both hemocyte concentration and phenoloxidase activity at the larval stage, and the effects of larval food restriction on phenoloxidase activity persisted when immunity was sampled at the adult stage. Adult food restriction reduced only adult phenoloxidase activity but not hemocyte concentration. Parasite spore load decreased with one measure of larval immunity, but food restriction did not increase the probability of parasite infection. Across monarchs, we found a negative relationship between larval hemocyte concentration and pupal mass, and a trade-off between adult hemocyte concentration and adult life span was evident in parasitized female monarchs. Adult life span increased with phenoloxidase activity in some subsets of monarchs. Our results emphasize that food restriction can alter fitness and immunity across multiple life stages. Understanding the consequences of resource limitation for immune defense is therefore important for predicting how increasing constraints on wildlife resources will affect fitness and resistance to natural enemies.

A balance of Mad and Myc expression dictates larval cell apoptosis and adult stem cell development during Xenopus intestinal metamorphosis.

PubMed

Okada, Morihiro; Miller, Thomas C; Wen, Luan; Shi, Yun-Bo

2017-05-11

The Myc/Mad/Max network has long been shown to be an important factor in regulating cell proliferation, death and differentiation in diverse cell types. In general, Myc-Max heterodimers activate target gene expression to promote cell proliferation, although excess of c-Myc can also induce apoptosis. In contrast, Mad competes against Myc to form Mad-Max heterodimers that bind to the same target genes to repress their expression and promote differentiation. The role of the Myc/Mad/Max network during vertebrate development, especially, the so-called postembryonic development, a period around birth in mammals, is unclear. Using thyroid hormone (T3)-dependent Xenopus metamorphosis as a model, we show here that Mad1 is induced by T3 in the intestine during metamorphosis when larval epithelial cell death and adult epithelial stem cell development take place. More importantly, we demonstrate that Mad1 is expressed in the larval cells undergoing apoptosis, whereas c-Myc is expressed in the proliferating adult stem cells during intestinal metamorphosis, suggesting that Mad1 may have a role in cell death during development. By using transcription activator-like effector nuclease-mediated gene-editing technology, we have generated Mad1 knockout Xenopus animals. This has revealed that Mad1 is not essential for embryogenesis or metamorphosis. On the other hand, consistent with its spatiotemporal expression profile, Mad1 knockout leads to reduced larval epithelial apoptosis but surprisingly also results in increased adult stem cell proliferation. These findings not only reveal a novel role of Mad1 in regulating developmental cell death but also suggest that a balance of Mad and Myc controls cell fate determination during adult organ development.

A balance of Mad and Myc expression dictates larval cell apoptosis and adult stem cell development during Xenopus intestinal metamorphosis

PubMed Central

Okada, Morihiro; Miller, Thomas C; Wen, Luan; Shi, Yun-Bo

2017-01-01

The Myc/Mad/Max network has long been shown to be an important factor in regulating cell proliferation, death and differentiation in diverse cell types. In general, Myc–Max heterodimers activate target gene expression to promote cell proliferation, although excess of c-Myc can also induce apoptosis. In contrast, Mad competes against Myc to form Mad–Max heterodimers that bind to the same target genes to repress their expression and promote differentiation. The role of the Myc/Mad/Max network during vertebrate development, especially, the so-called postembryonic development, a period around birth in mammals, is unclear. Using thyroid hormone (T3)-dependent Xenopus metamorphosis as a model, we show here that Mad1 is induced by T3 in the intestine during metamorphosis when larval epithelial cell death and adult epithelial stem cell development take place. More importantly, we demonstrate that Mad1 is expressed in the larval cells undergoing apoptosis, whereas c-Myc is expressed in the proliferating adult stem cells during intestinal metamorphosis, suggesting that Mad1 may have a role in cell death during development. By using transcription activator-like effector nuclease-mediated gene-editing technology, we have generated Mad1 knockout Xenopus animals. This has revealed that Mad1 is not essential for embryogenesis or metamorphosis. On the other hand, consistent with its spatiotemporal expression profile, Mad1 knockout leads to reduced larval epithelial apoptosis but surprisingly also results in increased adult stem cell proliferation. These findings not only reveal a novel role of Mad1 in regulating developmental cell death but also suggest that a balance of Mad and Myc controls cell fate determination during adult organ development. PMID:28492553

Effects of chronic exposure to soft, acidic water on gill development and chloride cell numbers in embryo-larval brook trout, Salvelinus fontinalis

USGS Publications Warehouse

Conklin, D.J.; Mowbray, R.C.; Gingerich, W.H.

1992-01-01

Recruitment failure is considered to be a major factor contributing to the decline of fish populations in soft, acidic waters; direct mortality of embryo-larval fishes has been postulated as a major cause of the decline. Little is understood of the physiological consequences to embryo-larval fishes of prolonged exposure to soft, acidic waters; however, dysfunction of respiratory and ionoregulatory processes is suspected. In order to evaluate the effects of acid exposure on the respiratory and ionoregulatory systems of developing brook trout, Salvelinus fontinalis, differences in gill morphology and numbers of chloride cells were compared between groups cf developing embryo-larval fish continuously exposed to moderately hard well water (130.0 mg.l-1 as CaCO3, pH 7.94) or to reconstituted soft, acidic water (4.4 mg.l-1 as CaCO3, pH 5.25) designed to mimic acidic waters of northern Wisconsin acidified lakes. Exposures were maintained for up to 48 days (82 days after fertilization) during critical periods of growth and differentiation of branchial structures. The second right gill arch of each fish was examined for changes in the development of filaments and lamellae and for differences in numbers of chloride cells. Gills of fish that developed in soft, acidic water contained greater numbers of normal and degenerating chloride cells, exhibited hyperplasia of primary epithelium and multiple fusions of adjacent filaments and lamellar epithelium than the gills of control fish. Filament and lamellar lengths and numbers of lamellae per filament were significantly less (P< 0.05) in fish that developed in soft, acidic water than in fish exposed to well water.

Growth and Development of Larval Bay Scallops (Argopecten irradians) in Response to Early Exposure to High CO2

DTIC Science & Technology

2013-02-01

used  by  different  groups   on  post-­‐ metamorphic  life  stages  of  scallops...exposure  has  severe  effects  on  larval  growth   and  development  of  bay  scallop  (Argopecten  irradians).     Using ...Gallager  were  very  helpful  in  letting  me   use  their  space  at  ESL  for  my   culturing  experiments.

The design of a community-based health education intervention for the control of Aedes aegypti.

PubMed

Lloyd, L S; Winch, P; Ortega-Canto, J; Kendall, C

1994-04-01

This report describes the process used to develop locally appropriate educational materials and to implement the education component of a community-based Aedes aegypti control program in Merida, Yucatan, Mexico. The process is broken into five stages: formative research, developing recommendations for behavior change, development of educational messages, development and production of educational materials, and distribution of the materials. Appropriate terminology and taxonomies for dengue were obtained from open in-depth interviews; baseline data from a knowledge, beliefs, and practices questionnaire served to confirm this information. A larval survey of house lots was carried out to identify the Ae. aegypti larval production sites found on individual house lots. This enabled the program to target the most important larval habitats. Community groups were organized to work on the development of messages and production of the educational materials to be used. The education intervention was successful in stimulating changes in both knowledge and behavior, which were measured in the evaluations of the intervention. To be successful, community-based strategies must be flexible and adapted to the local setting because of ecologic, cultural, and social differences between localities.

Seasonal development of Leptotrombidium akamushi (Acari: Trombiculidae) under field temperatures.

PubMed

Takahashi, M; Morita, K; Tsuji, O; Misumi, H; Otsuji, J; Hori, E; Kawanura, A; Tanaka, H

1995-11-01

Engorged larvae of Leptotrombidium akamushi (Brumpt), a vector of scrub typhus, were reared in small plastic containers placed on the ground and fed fresh eggs of the collembolan Sinella curviseta Brook. Engorged larvae obtained in October developed into deutonymphs through protonymphs approximately 1 mo before winter and became dormant in the cold winter season (approximately 3 mo). Most deutonymphs developed into tritonymphs in April and adults in May. Females began laying eggs in mid-June and the numbers of unfed larvae showed a peak in August. The mites reared from July rapidly developed into adults by August, and laid eggs in September. Larvae were most abundant in October, and adults became dormant in the winter. The same adults laid eggs from early May to late June and, upon hatching, the larval population peaked in early July of the 2nd summer. Most larvae died before the 2nd winter. Eggs hatched approximately 3 wk after oviposition and longevity of unfed larvae was 2 mo. Because of this very short incubation period, L. akamushi larvae occur in the summer, whereas L. pallidum Nagayo, Miyagawa, Mitamura & Tamiya, and L. scutellare Nagayo, Miyagawa, Mitamura, Tamiya & Tenjin occur in the autumn, although 3 species lay eggs from May to August.

The insect central complex as model for heterochronic brain development-background, concepts, and tools.

PubMed

Koniszewski, Nikolaus Dieter Bernhard; Kollmann, Martin; Bigham, Mahdiyeh; Farnworth, Max; He, Bicheng; Büscher, Marita; Hütteroth, Wolf; Binzer, Marlene; Schachtner, Joachim; Bucher, Gregor

2016-06-01

The adult insect brain is composed of neuropils present in most taxa. However, the relative size, shape, and developmental timing differ between species. This diversity of adult insect brain morphology has been extensively described while the genetic mechanisms of brain development are studied predominantly in Drosophila melanogaster. However, it has remained enigmatic what cellular and genetic mechanisms underlie the evolution of neuropil diversity or heterochronic development. In this perspective paper, we propose a novel approach to study these questions. We suggest using genome editing to mark homologous neural cells in the fly D. melanogaster, the beetle Tribolium castaneum, and the Mediterranean field cricket Gryllus bimaculatus to investigate developmental differences leading to brain diversification. One interesting aspect is the heterochrony observed in central complex development. Ancestrally, the central complex is formed during embryogenesis (as in Gryllus) but in Drosophila, it arises during late larval and metamorphic stages. In Tribolium, it forms partially during embryogenesis. Finally, we present tools for brain research in Tribolium including 3D reconstruction and immunohistochemistry data of first instar brains and the generation of transgenic brain imaging lines. Further, we characterize reporter lines labeling the mushroom bodies and reflecting the expression of the neuroblast marker gene Tc-asense, respectively.

Effect of long-term forest fertilization on Scots pine xylem quality and wood borer performance.

PubMed

Heijari, Juha; Nerg, Anne-Marja; Kainulainen, Pirjo; Noldt, Uwe; Levula, Teuvo; Raitio, Hannu; Holopainen, Jarmo K

2008-01-01

We tested whether changes in long-term nutrient availability would affect the xylem quality and characteristics of Scots pine trees as a food source for the larvae of the xylophagous wood borer Hylotrupes bajulus L. (Cerambycidae). We looked for an effect of host plant growth and xylem structural traits on H. bajulus larval performance, and looked for delayed effects of long-term forest fertilization on xylem chemical quality. In general, larval performance was dependent on larval developmental stage. However, the growth of larvae also varied with host plant quality (increases in the concentration of nitrogen and carbon-based secondary compounds of xylem were correlated with a decrease in the larval growth rate). The greater annual growth of trees reduced tracheid length and correlated positively with second-instar H. bajulus growth rate. This is consistent with the hypothesis that intrinsic growth patterns of host plants influence the development of the xylophagous wood borer H. bajulus.

Experimental control and characterization of autophagy in Drosophila.

PubMed

Juhasz, Gabor; Neufeld, Thomas P

2008-01-01

Insects such as the fruit fly Drosophila melanogaster, which fundamentally reorganize their body plan during metamorphosis, make extensive use of autophagy for their normal development and physiology. In the fruit fly, the hepatic/adipose organ known as the fat body accumulates nutrient stores during the larval feeding stage. Upon entering metamorphosis, as well as in response to starvation, these nutrients are mobilized through a massive induction of autophagy, providing support to other tissues and organs during periods of nutrient deprivation. High levels of autophagy are also observed in larval tissues destined for elimination, such as the salivary glands and larval gut. Drosophila is emerging as an important system for studying the functions and regulation of autophagy in an in vivo setting. In this chapter we describe reagents and methods for monitoring autophagy in Drosophila, focusing on the larval fat body. We also describe methods for experimentally activating and inhibiting autophagy in this system and discuss the potential for genetic analysis in Drosophila to identify novel genes involved in autophagy.

Lineage-associated tracts defining the anatomy of the Drosophila first instar larval brain

PubMed Central

Hartenstein, Volker; Younossi-Hartenstein, Amelia; Lovick, Jennifer; Kong, Angel; Omoto, Jaison; Ngo, Kathy; Viktorin, Gudrun

2015-01-01

Fixed lineages derived from unique, genetically specified neuroblasts form the anatomical building blocks of the Drosophila brain. Neurons belonging to the same lineage project their axons in a common tract, which is labeled by neuronal markers. In this paper, we present a detailed atlas of the lineage-associated tracts forming the brain of the early Drosophila larva, based on the use of global markers (anti-Neuroglian, anti-Neurotactin, Inscuteable-Gal4>UAS-chRFP-Tub) and lineage-specific reporters. We describe 68 discrete fiber bundles that contain axons of one lineage or pairs/small sets of adjacent lineages. Bundles enter the neuropil at invariant locations, the lineage tract entry portals. Within the neuropil, these fiber bundles form larger fascicles that can be classified, by their main orientation, into longitudinal, transverse, and vertical (ascending/descending) fascicles. We present 3D digital models of lineage tract entry portals and neuropil fascicles, set into relationship to commonly used, easily recognizable reference structures such as the mushroom body, the antennal lobe, the optic lobe, and the Fasciclin II-positive fiber bundles that connect the brain and ventral nerve cord. Correspondences and differences between early larval tract anatomy and the previously described late larval and adult lineage patterns are highlighted. Our L1 neuro-anatomical atlas of lineages constitutes an essential step towards following morphologically defined lineages to the neuroblasts of the early embryo, which will ultimately make it possible to link the structure and connectivity of a lineage to the expression of genes in the particular neuroblast that gives rise to that lineage. Furthermore, the L1 atlas will be important for a host of ongoing work that attempts to reconstruct neuronal connectivity at the level of resolution of single neurons and their synapses. PMID:26141956

Lineage-associated tracts defining the anatomy of the Drosophila first instar larval brain.

PubMed

Hartenstein, Volker; Younossi-Hartenstein, Amelia; Lovick, Jennifer K; Kong, Angel; Omoto, Jaison J; Ngo, Kathy T; Viktorin, Gudrun

2015-10-01

Fixed lineages derived from unique, genetically specified neuroblasts form the anatomical building blocks of the Drosophila brain. Neurons belonging to the same lineage project their axons in a common tract, which is labeled by neuronal markers. In this paper, we present a detailed atlas of the lineage-associated tracts forming the brain of the early Drosophila larva, based on the use of global markers (anti-Neuroglian, anti-Neurotactin, inscuteable-Gal4>UAS-chRFP-Tub) and lineage-specific reporters. We describe 68 discrete fiber bundles that contain axons of one lineage or pairs/small sets of adjacent lineages. Bundles enter the neuropil at invariant locations, the lineage tract entry portals. Within the neuropil, these fiber bundles form larger fascicles that can be classified, by their main orientation, into longitudinal, transverse, and vertical (ascending/descending) fascicles. We present 3D digital models of lineage tract entry portals and neuropil fascicles, set into relationship to commonly used, easily recognizable reference structures such as the mushroom body, the antennal lobe, the optic lobe, and the Fasciclin II-positive fiber bundles that connect the brain and ventral nerve cord. Correspondences and differences between early larval tract anatomy and the previously described late larval and adult lineage patterns are highlighted. Our L1 neuro-anatomical atlas of lineages constitutes an essential step towards following morphologically defined lineages to the neuroblasts of the early embryo, which will ultimately make it possible to link the structure and connectivity of a lineage to the expression of genes in the particular neuroblast that gives rise to that lineage. Furthermore, the L1 atlas will be important for a host of ongoing work that attempts to reconstruct neuronal connectivity at the level of resolution of single neurons and their synapses. Copyright © 2015 Elsevier Inc. All rights reserved.

Role of emerald ash borer (Coleoptera: Buprestidae) larval vibrations in host-quality assessment by Tetrastichus planipennisi (Hymenoptera: Eulophidae).

PubMed

Ulyshen, Michael D; Mankin, Richard W; Chen, Yigen; Duan, Jian J; Poland, Therese M; Bauer, Leah S

2011-02-01

The biological control agent Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae) is a gregarious larval endoparasitoid of the emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive cambium-feeding species responsible for recent, widespread mortality of ash (Fraxinus spp.) in North America. T. planipennisi is known to prefer late-instar emerald ash borer, but the cues used to assess host size by this species and most other parasitoids of concealed hosts remain unknown. We sought to test whether vibrations produced by feeding emerald ash borer vary with larval size and whether there are any correlations between these cues and T. planipennisi progeny number (i.e., brood size) and sex ratio. The amplitudes and rates of 3-30-ms vibrational impulses produced by emerald ash borer larvae of various sizes were measured in the laboratory before presenting the larvae to T. planipennisi. Impulse-rate did not vary with emerald ash borer size, but vibration amplitude was significantly higher for large larvae than for small larvae. T. planipennisi produced a significantly higher proportion of female offspring from large hosts than small hosts and was shown in previous work to produce more offspring overall from large hosts. There were no significant correlations, however, between the T. planipennisi progeny data and the emerald ash borer sound data. Because vibration amplitude varied significantly with host size, however, we are unable to entirely reject the hypothesis that T. planipennisi and possibly other parasitoids of concealed hosts use vibrational cues to assess host quality, particularly given the low explanatory potential of other external cues. Internal chemical cues also may be important.

[Carbohydrate restriction in the larval diet causes oxidative stress in adult insects of Drosophila melanogaster].

PubMed

Rovenko, B M; Lushchak, V I; Lushchak, O V

2013-01-01

The influence of 20 and 1% glucose and fructose, which were components of larval diet, on the level of oxidized proteins and lipids, low molecular mass antioxidant content as well as activities of antioxidant and associated enzymes in adult fruit fly Drosophila melanogaster were investigated. The restriction of carbohydrates in larval diet leads to oxidative stress in adult insects. It is supported by 40-50% increased content of protein carbonyl groups and by 60-70% decreased level of protein thiol groups as well as by a 4-fold increase of lipid peroxide content in 2-day-old flies of both sexes, developed on the diet with 1% carbohydrates. Oxidative stress, induced by carbohydrate restriction of the larval diet, caused the activation of antioxidant defence, differently exhibited in male and female fruit flies. Caloric restriction increased activity of superoxide dismutase and thioredoxin reductase associating only in males with 2-fold higher activity of NADPH-producing enzymes--glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase. Carbohydrate restriction in the larval diet caused the increase of uric acid content, but the decrease in catalase activity in males. In females the values of these parameters were changed in opposite direction compared with males. The obtained results let us conclude the different involvement of low molecular mass antioxidants, glutathione and uric acid, and antioxidant enzyme catalase in the protection of male and female fruit fly macromolecules against oxidative damages, caused by calorie restriction of larval diet.

The fate, distribution, and toxicity of lindane in tests with Chironomus riparius: effects of bioturbation and sediment organic matter content.

PubMed

Goedkoop, Willem; Peterson, Märit

2003-01-01

In this laboratory study, we address the effect of Chironomus bioturbation (0, 2,000, 6,000, and 18,000 ind/m2) and sediment organic matter content (10, 20, and 40%) on the fate, distribution, and bioavailability of 14C-lindane under standardized conditions in toxicity tests with artificial sediment. The results show that both Chironomus burrowing activity and sediment organic matter strongly modify test conditions. Larval mortality and development were inversely related with Chironomus densities and lindane concentration. Sediment organic matter content affected larval development rates but not mortality. Partitioning of lindane between the sediment, overlying water, and interstitial water was affected negatively by Chironomus larval densities: however, sediment partitioning was positively affected by sediment organic matter content. Bioturbation by Chironomus resulted in a remobilization of particle-associated lindane to the interstitial and overlying water, implying an increase in the bioavailability of the test compound. Strong positive relationships were found between Chironomus densities and lindane concentrations in interstitial water. The presence of Chironomus also resulted in lower label recovery. Label recovery on sediment particles ranged from 49 to 61% of initially added label in microcosms without Chironomus, from 41 to 56% at low larval densities, and from 15 to 50% at high larval densities. These results show that large discrepancies may exist between nominal test concentrations (from test compound additions) and true exposure concentrations even under standardized test conditions, which can introduce a relatively large error term in risk assessments. Calculations show that volatilization may be a quantitatively important sink for test compounds.

Binary Cell Fate Decisions and Fate Transformation in the Drosophila Larval Eye

PubMed Central

Rister, Jens; Ng, June; Celik, Arzu; Sprecher, Simon G.

2013-01-01

The functionality of sensory neurons is defined by the expression of specific sensory receptor genes. During the development of the Drosophila larval eye, photoreceptor neurons (PRs) make a binary choice to express either the blue-sensitive Rhodopsin 5 (Rh5) or the green-sensitive Rhodopsin 6 (Rh6). Later during metamorphosis, ecdysone signaling induces a cell fate and sensory receptor switch: Rh5-PRs are re-programmed to express Rh6 and become the eyelet, a small group of extraretinal PRs involved in circadian entrainment. However, the genetic and molecular mechanisms of how the binary cell fate decisions are made and switched remain poorly understood. We show that interplay of two transcription factors Senseless (Sens) and Hazy control cell fate decisions, terminal differentiation of the larval eye and its transformation into eyelet. During initial differentiation, a pulse of Sens expression in primary precursors regulates their differentiation into Rh5-PRs and repression of an alternative Rh6-cell fate. Later, during the transformation of the larval eye into the adult eyelet, Sens serves as an anti-apoptotic factor in Rh5-PRs, which helps in promoting survival of Rh5-PRs during metamorphosis and is subsequently required for Rh6 expression. Comparably, during PR differentiation Hazy functions in initiation and maintenance of rhodopsin expression. Hazy represses Sens specifically in the Rh6-PRs, allowing them to die during metamorphosis. Our findings show that the same transcription factors regulate diverse aspects of larval and adult PR development at different stages and in a context-dependent manner. PMID:24385925

Binary cell fate decisions and fate transformation in the Drosophila larval eye.

PubMed

Mishra, Abhishek Kumar; Tsachaki, Maria; Rister, Jens; Ng, June; Celik, Arzu; Sprecher, Simon G

2013-01-01

The functionality of sensory neurons is defined by the expression of specific sensory receptor genes. During the development of the Drosophila larval eye, photoreceptor neurons (PRs) make a binary choice to express either the blue-sensitive Rhodopsin 5 (Rh5) or the green-sensitive Rhodopsin 6 (Rh6). Later during metamorphosis, ecdysone signaling induces a cell fate and sensory receptor switch: Rh5-PRs are re-programmed to express Rh6 and become the eyelet, a small group of extraretinal PRs involved in circadian entrainment. However, the genetic and molecular mechanisms of how the binary cell fate decisions are made and switched remain poorly understood. We show that interplay of two transcription factors Senseless (Sens) and Hazy control cell fate decisions, terminal differentiation of the larval eye and its transformation into eyelet. During initial differentiation, a pulse of Sens expression in primary precursors regulates their differentiation into Rh5-PRs and repression of an alternative Rh6-cell fate. Later, during the transformation of the larval eye into the adult eyelet, Sens serves as an anti-apoptotic factor in Rh5-PRs, which helps in promoting survival of Rh5-PRs during metamorphosis and is subsequently required for Rh6 expression. Comparably, during PR differentiation Hazy functions in initiation and maintenance of rhodopsin expression. Hazy represses Sens specifically in the Rh6-PRs, allowing them to die during metamorphosis. Our findings show that the same transcription factors regulate diverse aspects of larval and adult PR development at different stages and in a context-dependent manner.

Evaluation of conventional PCR for detection of Strongylus vulgaris on horse farms.

PubMed

Bracken, M K; Wøhlk, C B M; Petersen, S L; Nielsen, M K

2012-03-23

Strongyle parasites are ubiquitous in grazing horses. Of these, the bloodworm Strongylus vulgaris is regarded as most pathogenic. Increasing levels of anthelmintic resistance in strongyle parasites has led to recommendations of decreased treatment intensities, and there is now a pronounced need for reliable tools for detection of parasite burdens in general and S. vulgaris in particular. The only method currently available for diagnosing S. vulgaris in practice is the larval culture, which is laborious and time-consuming, so veterinary practitioners most often pool samples from several horses together in one culture to save time. Recently, molecular tools have been developed to detect S. vulgaris in faecal samples. The aim of this study was to compare the performance of a conventional polymerase chain reaction (PCR) assay with the traditional larval culture and furthermore test the performance of pooled versus individual PCR for farm screening purposes. Faecal samples were obtained from 331 horses on 18 different farms. Farm size ranged from 6 to 56 horses, and horses aged between 2 months and 31 years. Larval cultures and PCR were performed individually on all horses. In addition, PCR was performed on 66 faecal pools consisting of 3-5 horses each. Species-specific PCR primers previously developed were used for the PCR. PCR and larval culture detected S. vulgaris in 12.1 and 4.5% of individual horses, respectively. On the farm level, eight farms tested positive with the larval culture, while 13 and 11 farms were positive with the individual and pooled PCRs, respectively. The individual PCR method was statistically superior to the larval culture, while no statistical difference could be detected between pooled and individual PCR for farm screening. In conclusion, pooled PCR appears to be a useful tool for farm screening for S. vulgaris. Copyright © 2011 Elsevier B.V. All rights reserved.

Integrating understanding of biophysical processes governing larval fish dispersal with basin-scale management decisions: lessons from the Missouri River, USA

NASA Astrophysics Data System (ADS)

Erwin, S. O.; Jacobson, R. B.; Fischenich, C. J.; Bulliner, E. A., IV; McDonald, R.; DeLonay, A. J.; Braaten, P.; Elliott, C. M.; Chojnacki, K.

2017-12-01

Management of the Missouri River—the longest river in the USA, with a drainage basin covering one sixth of the conterminous USA—is increasingly driven by the need to understand biophysical processes governing the dispersal of 8-mm long larval pallid sturgeon. In both the upper and lower basin, survival of larval sturgeon is thought to be a bottleneck limiting populations, but because of different physical processes at play, different modeling frameworks and resolutions are required to link management actions with population-level responses. In the upper basin, a series of impoundments reduce the length of river for the drifting larval sturgeon to complete their development. Downstream from the mainstem dams, recruitment is most likely diminished by channelization and reduced floodplain connectivity that limit the benthic habitat available for larval sturgeon to settle and initiate feeding. We present a synthesis of complementary field studies, laboratory observations, and numerical simulations that evaluate the physical processes related to larval dispersal of sturgeon in the Missouri River basin. In the upper basin, we use one-dimensional advection-dispersion models, calibrated with field experiments conducted in 2016-2017 using surrogate particles and tracers, to evaluate reservoir management alternatives. Results of field experimentation and numerical modeling show that proposed management alternatives in the upper basin may be limited by insufficient lengths of flowing river for drifting larvae to fully develop into their juvenile lifestage. In the intensively engineered lower basin, we employ higher resolution measurements and models to evaluate potential for channel reconfiguration and flow alteration to promote successful interception of drifting larvae into supportive benthic habitats for the initiation of feeding and transition to the juvenile life stage. We illustrate how refined understanding of small-scale biophysical process has been incorporated into the basin-scale management framework, thereby prompting a shift in restoration actions and design.

Increased long-flight activity triggered in beet armyworm by larval feeding on diet containing Cry1Ac protoxin.

PubMed

Jiang, Xing Fu; Chen, Jian; Zhang, Lei; Sappington, Thomas W; Luo, Li Zhi

2013-01-01

Evaluating ecological safety and conducting pest risk analysis for transgenic crops are vitally important before their commercial planting. The beet armyworm, Spodoptera exigua, a long-distance migratory insect pest, is not a direct target of transgenic Cry1Ac-expressing cotton in China, but nevertheless it has recently become an important pest. Migrants leaving their natal field arrive in other appropriate habitat far away in a short time, often followed by larval outbreaks. S. exigua has low susceptibility to Cry1Ac. However, our results from laboratory experiments identified (i) sublethal effects of Cry1Ac protoxin on larval development rate, larval and pupal weight, and adult lifetime fecundity, and (ii) increased long-flight behavior triggered by Cry1Ac which may contribute to larval outbreaks elsewhere. No significant differences in larval mortality, pupation rate, adult emergence rate, longevity, pre-oviposition period, or oviposition period were observed between controls and larvae fed on artificial diet incorporating a low concentration of Cry1Ac protoxin. The negative sublethal effects on some developmental and reproductive traits and lack of effect on others suggest they do not contribute to the observed severity of S. exigua outbreaks after feeding on Cry1Ac cotton. Interestingly, the percentage of long fliers increased significantly when larvae were reared on diet containing either of two low-dose treatments of Cry1Ac, suggesting a possible increased propensity to disperse long distances triggered by Cry1Ac. We hypothesize that negative effects on development and reproduction caused by Cry1Ac in the diet are offset by increased flight propensity triggered by the poor food conditions, thereby improving the chances of escaping adverse local conditions before oviposition. Increased long-flight propensity in turn may amplify the area damaged by outbreak populations. This phenomenon might be common in other migratory insect pests receiving sublethal doses of Bt toxins and warrants further study.

Increased Long-Flight Activity Triggered in Beet Armyworm by Larval Feeding on Diet Containing Cry1Ac Protoxin

PubMed Central

Jiang, Xing Fu; Chen, Jian; Zhang, Lei; Sappington, Thomas W.; Luo, Li Zhi

2013-01-01

Evaluating ecological safety and conducting pest risk analysis for transgenic crops are vitally important before their commercial planting. The beet armyworm, Spodoptera exigua, a long-distance migratory insect pest, is not a direct target of transgenic Cry1Ac-expressing cotton in China, but nevertheless it has recently become an important pest. Migrants leaving their natal field arrive in other appropriate habitat far away in a short time, often followed by larval outbreaks. S. exigua has low susceptibility to Cry1Ac. However, our results from laboratory experiments identified (i) sublethal effects of Cry1Ac protoxin on larval development rate, larval and pupal weight, and adult lifetime fecundity, and (ii) increased long-flight behavior triggered by Cry1Ac which may contribute to larval outbreaks elsewhere. No significant differences in larval mortality, pupation rate, adult emergence rate, longevity, pre-oviposition period, or oviposition period were observed between controls and larvae fed on artificial diet incorporating a low concentration of Cry1Ac protoxin. The negative sublethal effects on some developmental and reproductive traits and lack of effect on others suggest they do not contribute to the observed severity of S. exigua outbreaks after feeding on Cry1Ac cotton. Interestingly, the percentage of long fliers increased significantly when larvae were reared on diet containing either of two low-dose treatments of Cry1Ac, suggesting a possible increased propensity to disperse long distances triggered by Cry1Ac. We hypothesize that negative effects on development and reproduction caused by Cry1Ac in the diet are offset by increased flight propensity triggered by the poor food conditions, thereby improving the chances of escaping adverse local conditions before oviposition. Increased long-flight propensity in turn may amplify the area damaged by outbreak populations. This phenomenon might be common in other migratory insect pests receiving sublethal doses of Bt toxins and warrants further study. PMID:23675489

Effectiveness of recommended euthanasia methods in larval zebrafish (Danio rerio).

PubMed

Strykowski, Jennifer L; Schech, Joseph M

2015-01-01

The popularity of zebrafish and its use as a model organism in biomedical research including genetics, development, and toxicology, has increased over the past 20 y and continues to grow. However, guidelines for euthanasia remain vague, and the responsibility of creating appropriate euthanasia protocols essentially falls on individual facilities. To reduce variation in experimental results among labs, a standard method of euthanasia for zebrafish would be useful. Although various euthanasia methods have been compared, few studies focus on the effectiveness of euthanasia methods for larval zebrafish. In this study, we exposed larval zebrafish to each of 3 euthanasia agents (MS222, eugenol, and hypothermic shock) and assessed the recovery rate. Hypothermic shock appeared to be the most effective method for euthanizing zebrafish at 14 d after fertilization; however, this method may not be considered an efficient method for large numbers of larval zebrafish. Exposure to chemicals, such as MS222 and eugenol, were ineffective methods for euthanasia at this stage of development. When these agents are used, secondary measures should be taken to ensure death. Choosing a euthanasia method that is effective, efficient, and humane can be challenging. Determining a method of euthanasia that is suitable for fish of all stages will bring the zebrafish community closer to meeting this challenge.

Effectiveness of Recommended Euthanasia Methods in Larval Zebrafish (Danio rerio)

PubMed Central

Strykowski, Jennifer L; Schech, Joseph M

2015-01-01

The popularity of zebrafish and its use as a model organism in biomedical research including genetics, development, and toxicology, has increased over the past 20 y and continues to grow. However, guidelines for euthanasia remain vague, and the responsibility of creating appropriate euthanasia protocols essentially falls on individual facilities. To reduce variation in experimental results among labs, a standard method of euthanasia for zebrafish would be useful. Although various euthanasia methods have been compared, few studies focus on the effectiveness of euthanasia methods for larval zebrafish. In this study, we exposed larval zebrafish to each of 3 euthanasia agents (MS222, eugenol, and hypothermic shock) and assessed the recovery rate. Hypothermic shock appeared to be the most effective method for euthanizing zebrafish at 14 d after fertilization; however, this method may not be considered an efficient method for large numbers of larval zebrafish. Exposure to chemicals, such as MS222 and eugenol, were ineffective methods for euthanasia at this stage of development. When these agents are used, secondary measures should be taken to ensure death. Choosing a euthanasia method that is effective, efficient, and humane can be challenging. Determining a method of euthanasia that is suitable for fish of all stages will bring the zebrafish community closer to meeting this challenge. PMID:25651096

Contrasting reproductive strategies in three deep-sea octocorals from eastern Canada: Primnoa resedaeformis, Keratoisis ornata, and Anthomastus grandiflorus

NASA Astrophysics Data System (ADS)

Mercier, A.; Hamel, J.-F.

2011-06-01

Various aspects of reproduction were studied in three deep-sea octocorals belonging to the order Alcyonacea that co-occur at bathyal depths on the continental edge and the slope of eastern Canada. The main goals were to expand knowledge of deep-water heterotrophic corals and ascertain whether reproductive strategies could explain the known patterns of occurrence. Anthomastus grandiflorus is a gonochoric species with a female-biased sex ratio that exhibits internal fertilization and brooding of planula larvae. Conversely, Primnoa resedaeformis and Keratoisis ornata rely on broadcast spawning and external fertilization; their sexuality remains undetermined as spermatocysts were not found. In P. resedaeformis, the presence of mixed size classes of oocytes in samples from all months, depths, and locations studied suggests continuous oogenesis or overlapping development of oocyte cohorts, indicative of a gametogenic cycle spanning more than a year. No evidence of periodicity was found in this species, although it could have been masked by the striking bathymetric variation in potential relative fecundity (oocytes polyp-1). The two other octocorals displayed a clear annual breeding pattern. Spawning in K. ornata and larval release in A. grandiflorus occurred in late summer and fall, respectively, possibly in response to environmental factors, as supported by shifts in the reproductive peak of A. grandiflorus across latitudes. The three species are presumed to share a nonfeeding larval mode, and data on their reproductive potential do not present any striking disparities. Published data on bycatches and video surveys in Atlantic Canada indicate that the gonochoric brooder A. grandiflorus is more widely distributed than the two free spawners, P. resedaeformis and K. ornata, which is contrary to common dispersal potential paradigms.

Orchestrating change: The thyroid hormones and GI-tract development in flatfish metamorphosis.

PubMed

Gomes, A S; Alves, R N; Rønnestad, I; Power, D M

2015-09-01

Metamorphosis in flatfish (Pleuronectiformes) is a late post-embryonic developmental event that prepares the organism for the larval-to-juvenile transition. Thyroid hormones (THs) play a central role in flatfish metamorphosis and the basic elements that constitute the thyroid axis in vertebrates are all present at this stage. The advantage of using flatfish to study the larval-to-juvenile transition is the profound change in external morphology that accompanies metamorphosis making it easy to track progression to climax. This important lifecycle transition is underpinned by molecular, cellular, structural and functional modifications of organs and tissues that prepare larvae for a successful transition to the adult habitat and lifestyle. Understanding the role of THs in the maturation of organs and tissues with diverse functions during metamorphosis is a major challenge. The change in diet that accompanies the transition from a pelagic larvae to a benthic juvenile in flatfish is associated with structural and functional modifications in the gastrointestinal tract (GI-tract). The present review will focus on the maturation of the GI-tract during metamorphosis giving particular attention to organogenesis of the stomach a TH triggered event. Gene transcripts and biological processes that are associated with GI-tract maturation during Atlantic halibut metamorphosis are identified. Gene ontology analysis reveals core biological functions and putative TH-responsive genes that underpin TH-driven metamorphosis of the GI-tract in Atlantic halibut. Deciphering the specific role remains a challenge. Recent advances in characterizing the molecular, structural and functional modifications that accompany the appearance of a functional stomach in Atlantic halibut are considered and future research challenges identified. Copyright © 2014 Elsevier Inc. All rights reserved.

Quaternary paleoecology of aquatic Diptera in tropical and Southern Hemisphere regions, with special reference to the Chironomidae

NASA Astrophysics Data System (ADS)

Verschuren, Dirk; Eggermont, Hilde

2006-08-01

Chironomid paleoecology in north-temperate regions has made tremendous progress over the past decade, but studies in tropical and Southern Hemisphere regions remain relatively scarce. Reasons for this imbalance are (1) incomplete taxonomic knowledge of chironomid faunas outside Europe and North America, (2) a scarcity of ecological data on local species and genera that might confer bio-indicator value to them, and (3) logistic difficulties hampering the lake surveying necessary to develop paleoenvironmental calibration data sets. Thus far, most chironomid paleoecology in tropical and Southern Hemisphere regions has relied on an indicator-species approach, combining autecological information on local species of which larval morphology is known with the traditional ecological typology of chironomid genera transferred from the Holarctic region. This paper reviews work accomplished to date in tropical and temperate South America, Australia, Africa, and New Zealand, including studies on various families of non-chironomid Diptera with diagnostic fossils. Research has focused mostly on late-Glacial and Holocene climate reconstruction, less on tracing past human disturbance of aquatic ecosystems and their drainage basins. Quantitative chironomid-based paleoenvironmental reconstruction has so far been done only in Australia and Africa. These studies compensated for the lack of traditional surface-sediment calibration data sets, nowadays often the main source of quantitative information on species ecological optima and tolerances, by maximally exploiting archival species-distribution data based on live collections of adult and/or larval midges. This stimulated efforts to achieve trustworthy species-level identification of fossil chironomid remains, and, as a result, the taxonomic resolution of paleoecological studies in Australia and Africa is higher on average than that achieved in European and North American studies.

Energy density of zooplankton and fish larvae in the southern Catalan Sea (NW Mediterranean)

NASA Astrophysics Data System (ADS)

Barroeta, Ziortza; Olivar, M. Pilar; Palomera, Isabel

2017-06-01

In marine communities, energy of small planktonic organisms is transferred to their predators through feeding. The energy accumulated as organic substances by the different plankton organisms (Energetic Density content, ED) has been analysed in high latitudes and tropical areas, but not in the Mediterranean Sea. In this study, we approach this type of investigation for Mediterranean plankton through measures of total calorimetric content using an oxygen bomb calorimeter. We examined the spatiotemporal variation in the ED of microplankton (50-200 μm) and mesozooplankton (200-2000 μm), and two plankton-consumers, sardine (Sardina pilchardus) and anchovy (Engraulis encrasicolus) larvae. The study was carried out during the winter and summer of 2013 off the Ebro River Delta (NW Mediterranean Sea). Both plankton fractions showed a more coastal distribution and higher biomasses during winter, the period of sardine larvae occurrences, in front of a wider cross-shelf distribution and lower biomasses in summer, when anchovy appeared. ED values increased with the size of each plankton component, i.e., microzooplankton < mesozooplankton < fish larvae. A tendency for higher plankton ED in the winter period was observed, although being only significant for coastal zone, associated to the more productive waters there. Sardine and anchovy larvae showed an increasing trend in the amount of energy during development, with significantly lower ED between early larvae (6-10 mm standard length) and late postflexion stages (16-20 mm standard length). Small larvae of both species departed from a similarly low ED content, but in the next two size classes sardine larvae showed higher ED values than anchovy, being significantly higher in the 16-20 mm size class. Information on larval feeding patterns and larval growth rates for each species were used to discuss differences in energy allocation strategies.

Environmental Correlates of Abundances of Mosquito Species and Stages in Discarded Vehicle Tires

PubMed Central

YEE, DONALD A.; KNEITEL, JAMIE M.; JULIANO, STEVEN A.

2012-01-01

Discarded vehicle tires are a common habitat for container mosquito larvae, although the environmental factors that may control their presence or abundance within a tire are largely unknown. We sampled discarded vehicle tires in six sites located within four counties of central Illinois during the spring and summer of 2006 to determine associations between a suite of environmental factors and community composition of container mosquitoes. Our goal was to find patterns of association between environmental factors and abundances of early and late instars. We hypothesized that environmental factors correlated with early instars would be indicative of oviposition cues, whereas environmental factors correlated with late instars would be those important for larval survival. We collected 13 species of mosquitoes, with six species (Culex restuans, Cx. pipiens, Aedes albopictus, Cx. salinarius, Ae. atropalpus, and Ae. triseriatus) accounting for ≈95% of all larvae. There were similar associations between congenerics and environmental factors, with Aedes associated with detritus type (fine detritus, leaves, seeds) and Culex associated with factors related to the surrounding habitat (human population density, canopy cover, tire size) or microorganisms (bacteria, protozoans). Although there was some consistency in factors that were important for early and late instar abundance, there were few significant associations between early and late instars for individual species. Lack of correspondence between factors that explain variation in early versus late instars, most notable for Culex, suggests a difference between environmental determinants of oviposition and survival within tires. Environmental factors associated with discarded tires are important for accurate predictions of mosquito occurrence at the generic level. PMID:20180308

Larval development assays reveal the presence of sub-populations showing high- and low-level resistance in a monepantel (Zolvix®)-resistant isolate of Haemonchus contortus.

PubMed

Raza, Ali; Lamb, Jane; Chambers, Michael; Hunt, Peter W; Kotze, Andrew C

2016-04-15

Resistance to the amino-acetonitrile derivative monepantel has been reported in several species of gastrointestinal nematodes over recent years. We were interested in the use of in vitro assays with free-living worm life-stages to detect resistance to this drug. We therefore used larval development and larval migration assays to examine dose response relationships for the drug against two susceptible and one resistant isolate of Haemonchus contortus. The resistant isolate was established by laboratory propagation of the survivors of a field treatment with Zolvix(®) that had originally resulted in a drug efficacy of over 99%. Drug efficacy against this field-derived laboratory-propagated resistant isolate in vivo was approximately 15%. The larval development assay proved able to discriminate between the susceptible and resistant isolates, with larvae of the resistant isolate showing an ability to develop at higher drug concentrations than the two susceptible isolates. The resistant isolate showed the presence of two distinct subpopulations, separated by a plateau in the dose-response curve. Sub-population 1 (approximately 40% of the total population) showed a low level of resistance with an IC50 increased approximately 7-fold compared to the baseline susceptible isolate, while sub-population 2 (the remaining 60% of the total population) showed an IC50 increased over 1000-fold compared to the baseline susceptible isolate. This level of resistance is unusually high for any gastrointestinal nematode species in drug dose-response in vitro assays. In contrast, the migration assay could not discriminate between the three isolates, with migration not reduced to zero at any of the drug concentrations tested. This study demonstrates that a larval development assay is able to detect resistance to monepantel in H. contortus, and that resistance can exist in two distinct forms. This suggests that at least two separate monepantel resistance mechanisms are acting within the worm isolate studied here, with one or more mechanisms conferring a much higher level of resistance than the other(s). Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Fitness consequences of larval exposure to Beauveria bassiana on adults of the malaria vector Anopheles stephensi.

PubMed

Vogels, Chantal B F; Bukhari, Tullu; Koenraadt, Constantianus J M

2014-06-01

Entomopathogenic fungi have shown to be effective in biological control of both larval and adult stages of malaria mosquitoes. However, a small fraction of mosquitoes is still able to emerge after treatment with fungus during the larval stage. It remains unclear whether fitness of these adults is affected by the treatment during the larval stage and whether they are still susceptible for another treatment during the adult stage. Therefore, we tested the effects of larval exposure to the entomopathogenic fungus Beauveria bassiana on fitness of surviving Anopheles stephensi females. Furthermore, we tested whether larval exposed females were still susceptible to re-exposure to the fungus during the adult stage. Sex ratio, survival and reproductive success were compared between non-exposed and larval exposed A. stephensi. Comparisons were also made between survival of non-exposed and larval exposed females that were re-exposed to B. bassiana during the adult stage. Larval treatment did not affect sex ratio of emerging mosquitoes. Larval exposed females that were infected died significantly faster and laid equal numbers of eggs from which equal numbers of larvae hatched, compared to non-exposed females. Larval exposed females that were uninfected had equal survival, but laid a significantly larger number of eggs from which a significantly higher number of larvae hatched, compared to non-exposed females. Larval exposed females which were re-exposed to B. bassiana during the adult stage had equal survival as females exposed only during the adult stage. Our results suggest that individual consequences for fitness of larval exposed females depended on whether a fungal infection was acquired during the larval stage. Larval exposed females remained susceptible to re-exposure with B. bassiana during the adult stage, indicating that larval and adult control of malaria mosquitoes with EF are compatible. Copyright © 2014. Published by Elsevier Inc.

Spinal interneurons differentiate sequentially from those driving the fastest swimming movements in larval zebrafish to those driving the slowest ones.

PubMed

McLean, David L; Fetcho, Joseph R

2009-10-28

Studies of neuronal networks have revealed few general principles that link patterns of development with later functional roles. While investigating the neural control of movements, we recently discovered a topographic map in the spinal cord of larval zebrafish that relates the position of motoneurons and interneurons to their order of recruitment during swimming. Here, we show that the map reflects an orderly pattern of differentiation of neurons driving different movements. First, we use high-speed filming to show that large-amplitude swimming movements with bending along much of the body appear first, with smaller, regional swimming movements emerging later. Next, using whole-cell patch recordings, we demonstrate that the excitatory circuits that drive large-amplitude, fast swimming movements at larval stages are present and functional early on in embryos. Finally, we systematically assess the orderly emergence of spinal circuits according to swimming speed using transgenic fish expressing the photoconvertible protein Kaede to track neuronal differentiation in vivo. We conclude that a simple principle governs the development of spinal networks in which the neurons driving the fastest, most powerful swimming in larvae develop first with ones that drive increasingly weaker and slower larval movements layered on over time. Because the neurons are arranged by time of differentiation in the spinal cord, the result is a topographic map that represents the speed/strength of movements at which neurons are recruited and the temporal emergence of networks. This pattern may represent a general feature of neuronal network development throughout the brain and spinal cord.

Carryover effects of predation risk on postembryonic life-history stages in a freshwater shrimp.

PubMed

Ituarte, Romina Belén; Vázquez, María Guadalupe; González-Sagrario, María de los Ángeles; Spivak, Eduardo Daniel

2014-04-01

For organisms with complex life histories it is well known that risk experienced early in life, as embryos or larvae, may have effects throughout the life cycle. Although carryover effects have been well documented in invertebrates with different levels of parental care, there are few examples of predator-induced responses in externally brooded embryos. Here, we studied the effects of nonlethal predation risk throughout the embryonic development of newly spawned eggs carried by female shrimp on the timing of egg hatching, hatchling morphology, larval development and juvenile morphology. We also determined maternal body mass at the end of the embryonic period. Exposure to predation risk cues during embryonic development led to larger larvae which also had longer rostra but reached the juvenile stage sooner, at a smaller size and with shorter rostra. There was no difference in hatching timing, but changes in larval morphology and developmental timing showed that the embryos had perceived waterborne substances indicative of predation risk. In addition to carryover effects on larval and juvenile stages, predation threat provoked a decrease of body mass in mothers exposed to predator cues while brooding. Our results suggest that risk-exposed embryos were able to recognize the same infochemicals as their mothers, manifesting a response in the free-living larval stage. Thus, future studies assessing anti-predator phenotypes should include embryonic development, which seems to determine the morphology and developmental time of subsequent life-history stages according to perceived environmental conditions. Copyright © 2014 Elsevier GmbH. All rights reserved.

Effects of chlorpyrifos on in vitro sex steroid production and thyroid follicular development in adult and larval Lake Sturgeon, Acipenser fulvescens.

PubMed

Brandt, Catherine; Burnett, Duncan C; Arcinas, Liane; Palace, Vince; Gary Anderson, W

2015-08-01

Chlorpyrifos is a widely used organophosphate pesticide that has previously been shown to enter waterways in biologically relevant concentrations and has the potential to disrupt both thyroid hormone and sex steroid biosynthesis in vertebrates. Because gonadal maturation and larval development in Lake Sturgeon, Acipenser fulvescens, potentially coincide with the application of chlorpyrifos we examined the effects of chlorpyrifos on both thyroid follicular development in larval Lake Sturgeon, and sex hormone synthesis in adult Lake Sturgeon. For the first time, the present study reports steroidogenesis from testicular and ovarian tissue in Lake Sturgeon using an established in vitro bioassay. Furthermore, incubating gonad tissue with 5, 500 or 2000ngmL(-1) chlorpyrifos revealed an inhibitory effect on testosterone synthesis in both testicular (control, 40.29pgmg(-1) tissue wet weight(-1)h(-1) compared to experimental, 21.84pgmg(-1) tissue wet weight(-1)h(-1)) and ovarian (control, 33.83pgmg(-1) tissue wet weight(-1)h(-1) compared to experimental, 15.19pgmg(-1) tissue wet weight(-1)h(-1)) tissue. In a second series of experiments, larval Lake Sturgeon were exposed to equivalent concentrations of chlorpyrifos as above for 10days (d) between hatch and the onset of exogenous feeding. Larvae from each treatment group were raised until 67days post hatch (dph) and growth rates were compared alongside key indicators of thyroid follicle growth. Chlorpyrifos treatment had no effect on the measured indicators of thyroid follicular development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Embryotoxic effects of environmental chemicals: tests with the South African clawed toad (Xenopus laevis)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dumpert, K.

1987-06-01

In the course of the investigations reported below, it was shown that p-chloroaniline has a lethal effect on the embryos of Xenopus laevis at a concentration of 100 ppm and is development inhibiting (teratogenic) at concentrations of 1 and 10 ppm, respectively. In the case of aniline, a significant development-inhibiting effect was observed at a concentration as low as 1 ppm. A toxic effect was caused by concentrations between 30 and 40 ppm during embryogenesis and by concentrations above 40 ppm during larval development. A very conspicuous finding was an inhibiting effect of 20 to 40 ppm aniline on pigmentationmore » during embryogenesis and of a concentration as low as 1 ppm on the body size of the young toads. In the case of potassium dichromate, it was possible to barely detect a weak development-inhibiting effect during embryogenesis but no development-retarding effect during larval development. Toxic effects of potassium dichromate occurred during embryogenesis at concentrations of 5 and 7.5 ppm and during the larval development at concentrations above 10 ppm. Sodium dodecylbenzenesulfonic acid at a concentration of 50 ppm was found to have such a strong embryolethal effect that 80% of the eggs showed no cell division at all and the remaining 20% developed to only the bicellular stage. A teratogenic effect of this substance was not observed. Phenol, too, was found to be toxic at a concentration of 50 ppm; in contrast to sodium dodecylbenzenesulfonic acid, however, it did not show any lethal effect on the embryos but it did on the tadpoles, mainly in the first stages of larval development. Lower concentrations of phenol (5 and 10 ppm) had a nonsignificant inhibiting effect on the growth of the larvae. A teratogenic effect of phenol was not detected.« less

Surface ultrastructural studies on the germination, penetration and conidial development of Aspergillus flavus Link:Fries infecting silkworm, Bombyx mori Linn.

PubMed

Kumar, Vineet; Singh, G P; Babu, A M

2004-01-01

Aspergillosis is a common disease of the silkworm Bombyx mori Linn., caused by an insect mycopathogen Aspergillus flavus Link:Fries. The present study reveals the germination, penetration and conidial development of A. flavus on the larval integument of B. mori under SEM. Four different strains (NB18, KA, NB4D2 and NB7) of B. mori was surface inoculated with ca. of 1 x 10(6) conidia/ml. Each conidium germinated on the cuticle approximately 6 h after inoculation, forming a humpy or suctorial appressoria within 24 h. The hyphae which entered into haemocoel 2 day post-inoculation, grew and multiplied extensively, forming a mycelial complex, causing death of the host larva in about 4-5 days. This occurred with minimal breakdown of the internal tissues. Death of the host was followed by ramification of the fungus through the mesodermal and epidermal tissues, leading to larval mummification about 5-6 days after inoculation. Extensive fungal growths on the entire larval body followed, consisting of aerial hyphae, which developed branched conidiophores. The aerial hyphae with abundant conidiophores formed a confluent yellowish green fungal mat over the entire larval body in 6-7 days of post-inoculation. The tip of each emerging conidiophores gradually dilated and developed to become a bulbous head known as the vesicle. A large number of conidiogenous cells were produced over the entire surface of vesicle, which later developed into finger-like projections termed as sterigmata or phialides. The phialides matured within 2 days after the aerial hyphae emerged as evidenced by chains of conidia at their tips. The conidia were globose with externally roughened walls. The life cycle of the fungus on B. mori was completed in six to seven days.

Larval dispersion of the estuarine crab Neohelice granulata in coastal marine waters of the Southwest Atlantic

NASA Astrophysics Data System (ADS)

Bas, Claudia; Luppi, Tomás; Spivak, Eduardo; Schejter, Laura

2009-08-01

The estuarine brachyuran crab Neohelice granulata export their larvae from the parental intertidal population of the Mar Chiquita coastal lagoon, and probably other populations, to marine waters. The degree of larval dispersion or self-recruitment of populations is unknown. We evaluated the presence of all larval stages of N. granulata in coastal waters of Argentina between 37.9° and 35.8° S, at two different spatial scales: a broad scale of tens to hundreds of kilometers from the Río de la Plata estuary in the north, to Mar Chiquita lagoon in the south, and a small scale of hundreds of meters to some kilometers around the mouth of Mar Chiquita, during spring and summer. Additionally, we registered the larval composition and density at San Clemente creek population, in Samborombon Bay (Río de la Plata estuary), every 3 h along a 30-hour period. Evidence indicates that larval release of N. granulata is temporally synchronized with nocturnal ebb tides and all development from Zoea I to Zoea IV occur in areas close to the parental population, even with very different oceanographic characteristics. A possible mechanism based on salinity selection and wind-driven transport is proposed for such behavior, and some considerations related to the connectivity of present populations are made.

The impact of CO2-driven ocean acidification on early development and calcification in the sea urchin Strongylocentrotus intermedius.

PubMed

Zhan, Yaoyao; Hu, Wanbin; Zhang, Weijie; Liu, Minbo; Duan, Lizhu; Huang, Xianya; Chang, Yaqing; Li, Cong

2016-11-15

The impact of CO 2 -driven ocean acidification(OA) on early development and calcification in the sea urchin Strongylocentrotus intermedius cultured in northern Yellow Sea was investigated by comparing fertilization success, early cleavage rate, hatching rate of blastulae, larvae survival rate at 70h post-fertilization, larval morphology and calcification under present natural seawater condition (pH=8.00±0.03) and three laboratory-controlled acidified conditions (OA 1 , △pH=-0.3units; OA 2 , △pH=-0.4units; OA 3 , △pH=-0.5units) projected by IPCC for 2100. Results showed that pH decline had no effect on the overall fertilization, however, with decreased pH, delayed early embryonic cleavage, reduced hatching rate of blastulae and four-armed larvae survival rate at 70h post-fertilization, impaired larval symmetry, shortened larval spicules, and corrosion spicule structure were observed in all OA-treated groups as compared to control, which indicated that CO 2 -driven OA affected early development and calcification in S. intermedius negatively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Entomocidal effects of beech apricot, Labramia bojeri, seed extract on a soybean pest, the velvetbean moth, Anticarsia gemmatalis, and its enzymatic activity

PubMed Central

Macedo, Maria L. R.; Kubo, Carlos E. G.; Freire, Maria G. M.; Júnior, Roberto T. A.; Parra, José R. P.

2014-01-01

Abstract The effects of the beech apricot, Labramia bojeri A. de Candolle (Sapotales: Sapotaceae), seed aqueous extract on the larval development of the velvetbean moth, Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae), was evaluated. The extract inhibited larval development, pupal weight, and survival and emergence of adults. Digestive proteolytic activity in larval midgut and feces extracts was determined. Larvae fed 10 g/L of the aqueous extract showed a significant reduction in trypsin activity (~64%), when compared with control larvae. Trypsin and chymotrypsin activities were also detected in fecal material in aqueous-extract-fed larvae, with about ~4.5 times more trypsin activity than the controls. The results from dietary utilization experiments with A. gemmatalis larvae showed a reduction in the efficiency of conversion of ingested food and digested food and an increase in approximate digestibility and metabolic cost. The effect of the extract suggests the potential use of L. bojeri seeds to inhibit the development of A. gemmatalis via oral exposure. The L. bojeri extract can be an alternative to other methods of control. PMID:25373174

EGF-mediated EGFR/ERK signaling pathway promotes germinative cell proliferation in Echinococcus multilocularis that contributes to larval growth and development

PubMed Central

Li, Xiu; Dai, Mengya; Wu, Jianjian; Guo, Xinrui; Tian, Huimin; Heng, Zhijie; Lu, Ying; Chai, Xiaoli

2017-01-01

Background Larvae of the tapeworm E. multilocularis cause alveolar echinococcosis (AE), one of the most lethal helminthic infections in humans. A population of stem cell-like cells, the germinative cells, is considered to drive the larval growth and development within the host. The molecular mechanisms controlling the behavior of germinative cells are largely unknown. Methodology/Principal findings Using in vitro cultivation systems we show here that the EGFR/ERK signaling in the parasite can promote germinative cell proliferation in response to addition of human EGF, resulting in stimulated growth and development of the metacestode larvae. Inhibition of the signaling by either the EGFR inhibitors CI-1033 and BIBW2992 or the MEK/ERK inhibitor U0126 impairs germinative cell proliferation and larval growth. Conclusions/Significance These data demonstrate the contribution of EGF-mediated EGFR/ERK signaling to the regulation of germinative cells in E. multilocularis, and suggest the EGFR/ERK signaling as a potential therapeutic target for AE and perhaps other human cestodiasis. PMID:28241017

Rearing two fruit flies pests on artificial diet with variable pH.

PubMed

Dias, N P; Nava, D E; Smaniotto, G; Garcia, M S; Valgas, R A

2018-04-23

Fruit flies (Diptera: Tephritidae) are considered the main fruit pests worldwide. In Brazil, two species are predominant: the South American fruit fly, Anastrepha fraterculus and the Mediterranean fruit fly, Ceratitis capitata. In this study, we evaluated the effect of artificial diets with variable pH in their larval development and adult performance. The experiments were carried out in the laboratory at 25 ± 2 °C, 70 ± 10% RH and 12:12h (L:D) photoperiod. Semisolid diets with pH values of 6.0, 5.0, 4.0, 3.0, 2.0, 1.5, and 1.0, adjusted by adding hydrochloric acid were tested. Results indicated that the diet with pH 6.0 did not support larval development of both species of fruit fly. Diets with greater acidic pH values did not allow egg, larvae or pupae development and adult reproduction of A. fraterculus. For C. capitata , the pH of artificial diet exerts greater influence compared to A. fraterculus on the duration and viability of the larval stage, number of pupae, sex ratio and longevity of males.

Rising water temperatures, reproduction and recruitment of an invasive oyster, Crassostrea gigas, on the French Atlantic coast.

PubMed

Dutertre, Mickaël; Beninger, Peter G; Barillé, Laurent; Papin, Mathias; Haure, Joël

2010-02-01

The recent appearance and invasion of feral oysters (Crassostrea gigas) along the northern European Atlantic coast, underscores the necessity to investigate the relationship between environmental variables, reproductive physiology, larval development and recruitment. We studied these relationships at both high (HT) and intermediate (IT) - turbidity sites, through historical data on water temperatures, multi-parameter environmental probes, histological analyses, and field collections of planktonic larvae and settled post-larvae in 2005 and 2006. A progressive warming trend was observed, especially since 1995, when oyster proliferation first became severe. Threshold temperatures for oocyte growth, larval development and settlement were achieved in both 2005 and 2006. The HT site showed greater numbers of larvae and post-larvae than the IT site for both years, with the highest numbers of post-larvae observed at both sites during the warmer summer of 2006. These results suggest that increased temperatures in northern European waters allow successful reproduction, larval development, and recruitment of C. gigas. High turbidity conditions further enhance this success. 2009 Elsevier Ltd. All rights reserved.

Molecular characterization of larval development from fertilization to metamorphosis in a reef-building coral.

PubMed

Strader, Marie E; Aglyamova, Galina V; Matz, Mikhail V

2018-01-04

Molecular mechanisms underlying coral larval competence, the ability of larvae to respond to settlement cues, determine their dispersal potential and are potential targets of natural selection. Here, we profiled competence, fluorescence and genome-wide gene expression in embryos and larvae of the reef-building coral Acropora millepora daily throughout 12 days post-fertilization. Gene expression associated with competence was positively correlated with transcriptomic response to the natural settlement cue, confirming that mature coral larvae are "primed" for settlement. Rise of competence through development was accompanied by up-regulation of sensory and signal transduction genes such as ion channels, genes involved in neuropeptide signaling, and G-protein coupled receptor (GPCRs). A drug screen targeting components of GPCR signaling pathways confirmed a role in larval settlement behavior and metamorphosis. These results gives insight into the molecular complexity underlying these transitions and reveals receptors and pathways that, if altered by changing environments, could affect dispersal capabilities of reef-building corals. In addition, this dataset provides a toolkit for asking broad questions about sensory capacity in multicellular animals and the evolution of development.

Developing optimum sample size and multistage sampling plans for Lobesia botrana (Lepidoptera: Tortricidae) larval infestation and injury in northern Greece.

PubMed

Ifoulis, A A; Savopoulou-Soultani, M

2006-10-01

The purpose of this research was to quantify the spatial pattern and develop a sampling program for larvae of Lobesia botrana Denis and Schiffermüller (Lepidoptera: Tortricidae), an important vineyard pest in northern Greece. Taylor's power law and Iwao's patchiness regression were used to model the relationship between the mean and the variance of larval counts. Analysis of covariance was carried out, separately for infestation and injury, with combined second and third generation data, for vine and half-vine sample units. Common regression coefficients were estimated to permit use of the sampling plan over a wide range of conditions. Optimum sample sizes for infestation and injury, at three levels of precision, were developed. An investigation of a multistage sampling plan with a nested analysis of variance showed that if the goal of sampling is focusing on larval infestation, three grape clusters should be sampled in a half-vine; if the goal of sampling is focusing on injury, then two grape clusters per half-vine are recommended.

Cell tracking supports secondary gastrulation in the moon jellyfish Aurelia.

PubMed

Gold, David A; Nakanishi, Nagayasu; Hensley, Nicholai M; Hartenstein, Volker; Jacobs, David K

2016-11-01

The moon jellyfish Aurelia exhibits a dramatic reorganization of tissue during its metamorphosis from planula larva to polyp. There are currently two competing hypotheses regarding the fate of embryonic germ layers during this metamorphosis. In one scenario, the original endoderm undergoes apoptosis and is replaced by a secondary endoderm derived from ectodermal cells. In the second scenario, both ectoderm and endoderm remain intact through development. In this study, we performed a pulse-chase experiment to trace the fate of larval ectodermal cells. We observed that prior to metamorphosis, ectodermal cells that proliferated early in larval development concentrate at the future oral end of the polyp. During metamorphosis, these cells migrate into the endoderm, extending all the way to the aboral portion of the gut. We therefore reject the hypothesis that larval endoderm remains intact during metamorphosis and provide additional support for the "secondary gastrulation" hypothesis. Aurelia appears to offer the first and only described case where a cnidarian derives its endoderm twice during normal development, adding to a growing body of evidence that germ layers can be dramatically reorganized in cnidarian life cycles.

Physiological and biochemical changes during the larval development of a brachyuran crab reared under constant conditions in the laboratory

NASA Astrophysics Data System (ADS)

Anger, K.; Harms, J.; Püschel, C.; Seeger, B.

1989-06-01

Larvae of the spider crab Hyas araneus were reared in the laboratory at constant conditions (12°C; 32‰S), and their feeding rate ( F), oxygen consumption ( R), nitrogen excretion ( U), and growth were measured in regular intervals of time during development from hatching to metamorphosis. Growth was measured as dry weight ( W), carbon ( C), nitrogen ( N), hydrogen ( H) protein, and lipid. All these physiological and biochemical traits revealed significant changes both from instar to instar and during individual larval moult cycles. Average F was low in the zoea I, reached a maximum in the zoea II, and decreased again in the megalopa. In the zoeal instars, it showed a bell-shaped pattern, with a maximum in the middle (zoea I) or during the first half of the moult cycle (zoea II). Maximum F in the megalopa was observed still earlier, during postmoult. Respiration ( R) increased in the zoeal instars as a linear function of time, whereas it showed a sinusoidal pattern in the megalopa. These findings on variation in F and R during larval development confirm results obtained in previous studies on H. araneus and other decapod species. Excretion ( U) was measured for the first time with a high temporal resolution in crab larvae. It showed in all three larval instars a bell-shaped variation pattern, with a maximum near the middle of the moult cycle, and significantly increasing average values from instar to instar. The atomic O/N ratio followed an inverse pattern, suggesting a maximum utilization of protein as a metabolic substrate during intermoult. Growth data from the present study and from a number of previous studies were compiled, showing consistency of growth patterns, but a considerable degree of variability between larvae from different hatches reared under identical conditions. The data show the following consistent tendencies: during the first part of each larval moult cycle (in postmoult, partly in intermoult), lipids are accumulated at a higher rate than protein, whereas an inverse growth patterns is typical of the later (premoult) stages. These two different growth phases are interpreted as periods dominated by reserve accumulation in the hepatopancreas, and epidermal growth and reconstruction (morphogenesis), respectively. Differences between individual larval instars in average biochemical composition and growth patterns may be related to different strategies: the zoeal instars and the early megalopa are pelagic feeding stages, accumulating energy reserves (principally lipids) necessary for the completion of larval development, whereas the later (premoult) megalopa is a semibenthic settling stage that converts a significant part of this energy to epidermal protein. The megalopa shifts in behaviour and energy partitioning from intense feeding activity and body growth to habitat selection and morphogenesis, preparing itself for metamorphosis, i.e. it shows an increasing degree of lecithotrophy. Data from numerous parallel elemental and biochemical analyses are compiled to show quantitative relationships between W, C, N, H, lipid, and protein. These regressions may be used as empirical conversion equations for estimates of single chemical components in larval Hyas araneus, and, possibly, other decapods.

Effect of CO2-related acidification on aspects of the larval development of the European lobster, Homarus gammarus (L.)

NASA Astrophysics Data System (ADS)

Arnold, K. E.; Findlay, H. S.; Spicer, J. I.; Daniels, C. L.; Boothroyd, D.

2009-03-01

Oceanic uptake of anthropogenic CO2 results in a reduction in pH termed "Ocean Acidification" (OA). Comparatively little attention has been given to the effect of OA on the early life history stages of marine animals. Consequently, we investigated the effect of culture in CO2-acidified sea water (approx. 1200 ppm, i.e. average values predicted using IPCC 2007 A1F1 emissions scenarios for year 2100) on early larval stages of an economically important crustacean, the European lobster Homarus gammarus. Culture in CO2-acidified sea water did not significantly affect carapace length or development of H. gammarus. However, there was a reduction in carapace mass during the final stage of larval development in CO2-acidified sea water. This co-occurred with a reduction in exoskeletal mineral (calcium and magnesium) content of the carapace. As the control and high CO2 treatments were not undersaturated with respect to any of the calcium carbonate polymorphs measured, the physiological alterations we record are most likely the result of acidosis or hypercapnia interfering with normal homeostatic function, and not a direct impact on the carbonate supply-side of calcification per se. Thus despite there being no observed effect on survival, carapace length, or zoeal progression, OA related (indirect) disruption of calcification and carapace mass might still adversely affect the competitive fitness and recruitment success of larval lobsters with serious consequences for population dynamics and marine ecosystem function.

Ammonia and urea handling by early life stages of fishes.

PubMed

Zimmer, Alex M; Wright, Patricia A; Wood, Chris M

2017-11-01

Nitrogen metabolism in fishes has been a focus of comparative physiologists for nearly a century. In this Review, we focus specifically on early life stages of fishes, which have received considerable attention in more recent work. Nitrogen metabolism and excretion in early life differs fundamentally from that of juvenile and adult fishes because of (1) the presence of a chorion capsule in embryos that imposes a limitation on effective ammonia excretion, (2) an amino acid-based metabolism that generates a substantial ammonia load, and (3) the lack of a functional gill, which is the primary site of nitrogen excretion in juvenile and adult fishes. Recent findings have shed considerable light on the mechanisms by which these constraints are overcome in early life. Perhaps most importantly, the discovery of Rhesus (Rh) glycoproteins as ammonia transporters and their expression in ion-transporting cells on the skin of larval fishes has transformed our understanding of ammonia excretion by fishes in general. The emergence of larval zebrafish as a model species, together with genetic knockdown techniques, has similarly advanced our understanding of ammonia and urea metabolism and excretion by larval fishes. It has also now been demonstrated that ammonia excretion is one of the primary functions of the developing gill in rainbow trout larvae, leading to new hypotheses regarding the physiological demands driving gill development in larval fishes. Here, we highlight and discuss the dramatic changes in nitrogen handling that occur over early life development in fishes. © 2017. Published by The Company of Biologists Ltd.

Life history traits and the activity of antioxidative enzymes in Lymantria dispar L. (lepidoptera, lymantriidae) larvae exposed to benzo[a]pyrene.

PubMed

Ilijin, Larisa; Mrdaković, Marija; Todorović, Dajana; Vlahović, Milena; Gavrilović, Anja; Mrkonja, Aleksandra; Perić-Mataruga, Vesna

2015-11-01

Increased presence of benzo[a]pyrene in the environment underlines the need for development of sensitive biomarkers for monitoring. Antioxidative enzymes could be used as early-warning signals because of their sensitivity and applicability. The activity of 2 antioxidative enzymes, superoxide dismutase (SOD) and catalase (CAT), were measured in midgut tissues of fifth instar Lymantria dispar larvae exposed to different concentrations of benzo[a]pyrene: 2 ng, 10 ng, 20 ng, 100 ng, 200 ng, and 2000 ng benzo[a]pyrene/g dry food weight. Larval development, larval mass, and relative growth rate were also monitored. The authors detected prolonged larval development, as well as reduced larval mass and relative growth rate in larvae exposed to all benzo[a]pyrene concentrations. The L. dispar midgut SOD activity was significantly increased, and 2 SOD isoforms were detected on native polyacrylamide gel electrophoresis in larvae fed on artificial diet supplemented with benzo[a]pyrene. In contrast, the control group had only 1 isoform. Catalase activity was significantly increased in all benzo[a]pyrene-treated larvae. Native gel electrophoresis showed that a switch in active CAT isoforms occurred after benzo[a]pyrene treatment. Thus, SOD and CAT in polyphagous herbivorous L. dispar larvae are very sensitive to low concentrations of benzo[a]pyrene. Therefore, they could be used as biomarkers for exposure and effects of this toxic polycyclic aromatic hydrocarbon. © 2015 SETAC.

Spawning, fertilization, and larval development of Potamocorbula amurensis (Mollusca: Bivalvia) from San Francisco Bay, California

USGS Publications Warehouse

Nicolini, M.H.; Penry, D.L.

2000-01-01

In Potamocorbula amurensis time for development to the straight-hinge larval stage is 48 hr at 15??C. Potamocorbula amurensis settles at a shell length of approximately 135 ??m 17 to 19 days after fertilization. Our observations of timing of larval devdlopment in P. amurensis support the hypothesis of earlier workers that its route of initial introduction to San Francisco Bay was as veliger larvae transported in ballast water by trans-Pacific cargo ships. The length of the larval period of P. amurensis relative to water mass residence times in San Francisco Bay suggests that it is sufficient to allow substantial dispersal from North Bay to South Bay populations in concordance with previous observations that genetic differentiation among populations of P. amurensis in San Francisco Bay is low. Potamocorbula amurensis is markedly euryhaline at all stages of development. Spawning and fertilization can occur at salinities from 5 to 25 psu, and eggs and sperms can each tolerance at least a 10-psu step increase or decrease in salinity. Embryos that are 2 hr old can tolerate the same range of salinities from (10 to 30 psu), and by the time they are 24 hr old they can tolerate the same range of salinities (2 to 30 psu) that adult clams can. The ability of P. amurensis larvae to tolerate substantial step changes in salinity suggests a strong potential to survive incomplete oceanic exchanges of ballast water and subsequent discharge into receiving waters across a broad range of salinities.

Impacts of ocean acidification on gene expression and biomineralisation in the Pacific oyster Crassostrea gigas Thunberg, 1793

NASA Astrophysics Data System (ADS)

Bagusche, F.; Pouvreau, S.; Trueman, C.; Long, S.; Hauton, C.

2012-04-01

The published evidence of impacts of ocean acidification and on marine calcifiers has emphasized the need to understand the molecular mechanisms of biomineralisation. Crassostrea gigas is an ideal organism to examine these processes as: 1) the hatchery rearing of larval stages is well constrained, 2) studies have established an ontogenetic switch in deposition of carbonate polymorphs from aragonite in larval shells to calcite in adults and 3) it is a globally-important commercial species. Research summarized in this presentation will identify some of the molecular mechanisms involved in calcification processes during ontogeny of Crassostrea gigas, as well as possible impacts of changes in environmental conditions such as temperature and pH. Data will be presented from a quantitative real-time PCR study of the changes in gene expression during development in different environments. Additionally scanning electron microscopy and infrared spectroscopy analyses of shell microstructures and composition will be summarised to correlate changes in gene expression with end-point differences in shell structure. Preliminary results suggest that changes in the environmental conditions lead to differences in expression patterns of genes involved in biomineralisation processes. The combined effects of ambient seawater temperature and low pH show the greatest negative effect on larval shell development, identified as malformations, eroded shell surfaces and a significant decrease in shell size. However, the effect of higher seawater temperature seems to amend the effects of ocean acidification on larval shell development.

Control of movement initiation underlies the development of balance

PubMed Central

Ehrlich, David E.; Schoppik, David

2017-01-01

Summary Balance arises from the interplay of external forces acting on the body and internally generated movements. Many animal bodies are inherently unstable, necessitating corrective locomotion to maintain stability. Understanding how developing animals come to balance remains a challenge. Here we study the interplay between environment, sensation, and action as balance develops in larval zebrafish. We first model the physical forces that challenge underwater balance and experimentally confirm that larvae are subject to constant destabilization. Larvae propel in swim bouts that, we find, tend to stabilize the body. We confirm the relationship between locomotion and balance by changing larval body composition, exacerbating instability and eliciting more frequent swimming. Intriguingly, developing zebrafish come to control the initiation of locomotion, swimming preferentially when unstable, thus restoring preferred postures. To test the sufficiency of locomotor-driven stabilization and the developing control of movement timing, we incorporate both into a generative model of swimming. Simulated larvae recapitulate observed postures and movement timing across early development, but only when locomotor-driven stabilization and control of movement initiation are both utilized. We conclude the ability to move when unstable is the key developmental improvement to balance in larval zebrafish. Our work informs how emerging sensorimotor ability comes to impact how and why animals move when they do. PMID:28111151

Brain development in the yellow fever mosquito Aedes aegypti: a comparative immunocytochemical analysis using cross-reacting antibodies from Drosophila melanogaster.

PubMed

Mysore, Keshava; Flister, Susanne; Müller, Pie; Rodrigues, Veronica; Reichert, Heinrich

2011-12-01

Considerable effort has been directed towards understanding the organization and function of peripheral and central nervous system of disease vector mosquitoes such as Aedes aegypti. To date, all of these investigations have been carried out on adults but none of the studies addressed the development of the nervous system during the larval and pupal stages in mosquitoes. Here, we first screen a set of 30 antibodies, which have been used to study brain development in Drosophila, and identify 13 of them cross-reacting and labeling epitopes in the developing brain of Aedes. We then use the identified antibodies in immunolabeling studies to characterize general neuroanatomical features of the developing brain and compare them with the well-studied model system, Drosophila melanogaster, in larval, pupal, and adult stages. Furthermore, we use immunolabeling to document the development of specific components of the Aedes brain, namely the optic lobes, the subesophageal neuropil, and serotonergic system of the subesophageal neuropil in more detail. Our study reveals prominent differences in the developing brain in the larval stage as compared to the pupal (and adult) stage of Aedes. The results also uncover interesting similarities and marked differences in brain development of Aedes as compared to Drosophila. Taken together, this investigation forms the basis for future cellular and molecular investigations of brain development in this important disease vector. © Springer-Verlag 2011

Ontogeny and distribution of alkaline and acid phosphatases in the digestive system of California halibut larvae (Paralichthys californicus).

PubMed

Zacarias-Soto, Magali; Barón-Sevilla, Benjamín; Lazo, Juan P

2013-10-01

Studies aimed to assess the digestive physiology of marine fish larvae under culture conditions are important to further understand the functional characteristics and digestive capacities of the developing larvae. Most studies to date concentrate on intestinal lumen digestion and little attention to the absorption process. Thus, the objectives of this study were to histochemically detect and quantify some of the enzymes responsible for absorption and intracellular digestion of nutrients in the anterior and posterior intestine of California halibut larvae. Alkaline and acid phosphatases were detected from the first days post-hatch (dph). Alkaline phosphatase maintained a high level of activity during the first 20 dph in both intestinal regions. Thereafter, a clear intestinal regionalization of the activity was observed with the highest levels occurring in the anterior intestine. Acid phosphatase activity gradually increased in both intestinal regions during development, and a regionalization of the activity was not observed until late in development, once the ocular migration began. Highest levels were observed in the anterior intestine at the end of metamorphosis concomitant with the stomach development. The results from this study show some morphological and physiological changes are occurring during larval development and a clear regionalization of the absorption process as the larvae develops. These ontological changes must be considered in the elaboration of diets according to the digestive capacity of the larvae.

Put a tiger in your tank: the polyclad flatworm Maritigrella crozieri as a proposed model for evo-devo.

PubMed

Lapraz, François; Rawlinson, Kate A; Girstmair, Johannes; Tomiczek, Bartłomiej; Berger, Jürgen; Jékely, Gáspár; Telford, Maximilian J; Egger, Bernhard

2013-10-09

Polyclad flatworms are an early branching clade within the rhabditophoran Platyhelminthes. They provide an interesting system with which to explore the evolution of development within Platyhelminthes and amongst Spiralia (Lophotrochozoa). Unlike most other flatworms, polyclads undergo spiral cleavage (similar to that seen in some other spiralian taxa), they are the only free-living flatworms where development via a larval stage occurs, and they are the only flatworms in which embryos can be reared outside of their protective egg case, enabling embryonic manipulations. Past work has focused on comparing early cleavage patterns and larval anatomy between polyclads and other spiralians. We have selected Maritigrella crozieri, the tiger flatworm, as a suitable polyclad species for developmental studies, because it is abundant and large in size compared to other species. These characteristics have facilitated the generation of a transcriptome from embryonic and larval material and are enabling us to develop methods for gene expression analysis and immunofluorescence techniques. Here we give an overview of M. crozieri and its development, we highlight the advantages and current limitations of this animal as a potential evo-devo model and discuss current lines of research.

Put a tiger in your tank: the polyclad flatworm Maritigrella crozieri as a proposed model for evo-devo

PubMed Central

2013-01-01

Polyclad flatworms are an early branching clade within the rhabditophoran Platyhelminthes. They provide an interesting system with which to explore the evolution of development within Platyhelminthes and amongst Spiralia (Lophotrochozoa). Unlike most other flatworms, polyclads undergo spiral cleavage (similar to that seen in some other spiralian taxa), they are the only free-living flatworms where development via a larval stage occurs, and they are the only flatworms in which embryos can be reared outside of their protective egg case, enabling embryonic manipulations. Past work has focused on comparing early cleavage patterns and larval anatomy between polyclads and other spiralians. We have selected Maritigrella crozieri, the tiger flatworm, as a suitable polyclad species for developmental studies, because it is abundant and large in size compared to other species. These characteristics have facilitated the generation of a transcriptome from embryonic and larval material and are enabling us to develop methods for gene expression analysis and immunofluorescence techniques. Here we give an overview of M. crozieri and its development, we highlight the advantages and current limitations of this animal as a potential evo-devo model and discuss current lines of research. PMID:24107307

Growth and development of larval green frogs (Rana clamitans) exposed to multiple doses of an insecticide

USGS Publications Warehouse

Boone, M.D.; Bridges, C.M.; Rothermel, B.B.

2001-01-01

Our objective was to determine how green frogs (Rana clamitans) are affected by multiple exposures to a sublethal level of the carbamate insecticide, carbaryl, in outdoor ponds. Tadpoles were added to 1,000-1 ponds at a low or high density which were exposed to carbaryl 0, 1, 2, or 3 times. Length of the larval period, mass, developmental stage, tadpole survival, and proportion metamorphosed were used to determine treatment effects. The frequency of dosing affected the proportion of green frogs that reached metamorphosis and the developmental stage of tadpoles. Generally, exposure to carbaryl increased rates of metamorphosis and development. The effect of the frequency of carbaryl exposure on development varied with the density treatment; the majority of metamorphs and the most developed tadpoles came from high-density ponds exposed to carbaryl 3 times. This interaction suggests that exposure to carbaryl later in the larval period stimulated metamorphosis, directly or indirectly, under high-density conditions. Our study indicates that exposure to a contaminant can lead to early initiation of metamorphosis and that natural biotic factors can mediate the effects of a contaminant in the environment.

Overcrowding-mediated stress alters cell proliferation in key neuroendocrine areas during larval development in Rhinella arenarum.

PubMed

Distler, Mijal J; Jungblut, Lucas D; Ceballos, Nora R; Paz, Dante A; Pozzi, Andrea G

2016-02-01

Exposure to adverse environmental conditions can elicit a stress response, which results in an increase in endogenous corticosterone levels. In early life stages, it has been thoroughly demonstrated that amphibian larval growth and development is altered as a consequence of chronic stress by interfering with the metamorphic process, however, the underlying mechanisms involved have only been partially disentangled. We examined the effect of intraspecific competition on corticosterone levels during larval development of the toad Rhinella arenarum and its ultimate effects on cell proliferation in particular brain areas as well as the pituitary gland. While overcrowding altered the number of proliferating cells in the pituitary gland, hypothalamus, and third ventricle of the brain, no differences were observed in areas which are less associated with neuroendocrine processes, such as the first ventricle of the brain. Apoptosis was increased in hypothalamic regions but not in the pituitary. With regards to pituitary cell populations, thyrotrophs but not somatoatrophs and corticotrophs showed a decrease in the cell number in overcrowded larvae. Our study shows that alterations in growth and development, produced by stress, results from an imbalance in the neuroendocrine systems implicated in orchestrating the timing of metamorphosis. © 2016 Wiley Periodicals, Inc.

Horn fly larval survival in cattle dung is reduced by endophyte infection of tall fescue pasture.

PubMed

Parra, Leonardo; Mutis, Ana; Chacón, Manuel; Lizama, Marcelo; Rojas, Claudio; Catrileo, Adrián; Rubilar, Olga; Tortella, Gonzalo; Birkett, Michael A; Quiroz, Andrés

2016-07-01

The potential for using endophytic microorganisms in pest control has increased during the last 40 years. In this study, we investigated the impact of endophyte (Neotyphodium coenophialum) infection of cattle pasture upon the survival of the horn fly, Haematobia irritans, a major agricultural pest affecting livestock in many parts of the world. In laboratory assays, where cattle dung collected from endophyte-infected (E+) tall fescue cultivar K-31 was used as the oviposition substrate, larval development was significantly reduced compared with development on cattle dung from steers that grazed uninfected (E-) tall fescue. Furthermore, studies with cattle dung supplemented with the alkaloid fraction extracted from the endophytic fungi revealed significant larval mortality, and HPLC analysis identified two alkaloids, peramine and lolitrem B. The development of larvae was shown to be significantly reduced in field-collected cattle dung. These results suggest that part of the toxicity of alkaloids contained in endophytes is transferred to faecal matter, causing an increase in mortality of H. irritans. These data suggest that endophyte infection of cattle pasture, i.e. modified pasture management, can significantly affect horn fly development. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.