Contemporary evolution of a Lepidopteran species, Heliothis virescens, in response to modern agricultural practices.

PubMed

Fritz, Megan L; DeYonke, Alexandra M; Papanicolaou, Alexie; Micinski, Stephen; Westbrook, John; Gould, Fred

2018-01-01

Adaptation to human-induced environmental change has the potential to profoundly influence the genomic architecture of affected species. This is particularly true in agricultural ecosystems, where anthropogenic selection pressure is strong. Heliothis virescens primarily feeds on cotton in its larval stages, and US populations have been declining since the widespread planting of transgenic cotton, which endogenously expresses proteins derived from Bacillus thuringiensis (Bt). No physiological adaptation to Bt toxin has been found in the field, so adaptation in this altered environment could involve (i) shifts in host plant selection mechanisms to avoid cotton, (ii) changes in detoxification mechanisms required for cotton-feeding vs. feeding on other hosts or (iii) loss of resistance to previously used management practices including insecticides. Here, we begin to address whether such changes occurred in H. virescens populations between 1997 and 2012, as Bt-cotton cultivation spread through the agricultural landscape. For our study, we produced an H. virescens genome assembly and used this in concert with a ddRAD-seq-enabled genome scan to identify loci with significant allele frequency changes over the 15-year period. Genetic changes at a previously described H. virescens insecticide target of selection were detectable in our genome scan and increased our confidence in this methodology. Additional loci were also detected as being under selection, and we quantified the selection strength required to elicit observed allele frequency changes at each locus. Potential contributions of genes near loci under selection to adaptive phenotypes in the H. virescens cotton system are discussed. © 2017 John Wiley & Sons Ltd.

The Genetic Architecture of a Complex Ecological Trait: Host Plant Use in the Specialist Moth, Heliothis subflexa

PubMed Central

Oppenheim, Sara J.; Gould, Fred; Hopper, Keith R.

2012-01-01

We used genetic mapping to examine the genetic architecture of differences in host plant use between two species of noctuid moths, Heliothis subflexa, a specialist on Physalis spp., and its close relative, the broad generalist H. virescens. We introgressed H. subflexa chromosomes into the H. virescens background and analyzed 1,462 backcross insects. The effects of H. subflexa-origin chromosomes were small when measured as the percent variation explained in backcross populations (0.2 to 5%), but were larger when considered in relation to the interspecific difference explained (1.5 to 165%). Most significant chromosomes had effects on more than one trait, and their effects varied between years, sexes, and genetic backgrounds. Different chromosomes could produce similar phenotypes, suggesting that the same trait might be controlled by different chromosomes in different backcross populations. It appears that many loci of small effect contribute to the use of Physalis by H. subflexa. We hypothesize that behavioral changes may have paved the way for physiological adaptation to Physalis by the generalist ancestor of H. subflexa and H. virescens. PMID:23106701

Immune defence strategies of generalist and specialist insect herbivores

PubMed Central

Barthel, Andrea; Kopka, Isabell; Vogel, Heiko; Zipfel, Peter; Heckel, David G.; Groot, Astrid T.

2014-01-01

Ecological immunology examines the adaptive responses of animals to pathogens in relation to other environmental factors and explores the consequences of trade-offs between investment in immune function and other life-history traits. Among species of herbivorous insects, diet breadth may vary greatly, with generalists consuming a wide variety of plant families and specialists restricted to a few species. Generalists may thus be exposed to a wider range of pathogens exerting stronger selection on the innate immune system. To examine whether this produces an increase in the robustness of the immune response, we compared larvae of the generalist herbivore Heliothis virescens and the specialist Heliothis subflexa challenged by entomopathogenic and non-pathogenic bacteria. Heliothis virescens larvae showed lower mortality, a lower number of recoverable bacteria, lower proliferation of haemocytes and higher phagocytic activity. These results indicate a higher tolerance to entomopathogenic bacteria by the generalist, which is associated with a more efficient cell-mediated immune response by mechanisms that differ between these closely related species. Our findings provide novel insights into the consequences of diet breadth and related environmental factors, which may be significant in further studies to understand the ecological forces and investment trade-offs that shape the evolution of innate immunity. PMID:24943370

Ecdysteroidogenesis and development in Heliothis virescens (Lepidoptera: Noctuidae): Focus on PTTH-stimulated pathways.

PubMed

Scieuzo, Carmen; Nardiello, Marisa; Salvia, Rosanna; Pezzi, Marco; Chicca, Milvia; Leis, Marilena; Bufo, Sabino A; Vinson, S Bradleigh; Rao, Asha; Vogel, Heiko; Falabella, Patrizia

2018-02-15

Post-embryonic development and molting in insects are regulated by endocrine changes, including prothoracicotropic hormone (PTTH)-stimulated ecdysone secretion by the prothoracic glands (PGs). In Lepidoptera, two pathways are potentially involved in PTTH-stimulated ecdysteroidogenesis, mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase/protein kinase B/target of rapamycin (PI3K/Akt/TOR). We investigated the potential roles of both these pathways in Heliothis virescens ecdysteroidogenesis. We identified putative proteins belonging to MAPK and PI3K/Akt/TOR signaling cascades, using transcriptomic analyses of PGs from last (fifth) instar larvae. Using western blots, we measured the phosphorylation of 4E-BP and S6K proteins, the main targets of TOR, following the in vitro exposure of PGs to brain extract containing PTTH (hereafter referred to as PTTH) and/or the inhibitors of MAPK (U0126), PI3K (LY294002) or TOR (rapamycin). Next, we measured ecdysone production, under the same experimental conditions, by enzyme immunoassay (EIA). We found that in Heliothis virescens last instar larvae, both pathways modulated PTTH-stimulated ecdysteroidogenesis. Finally, we analyzed the post-embryonic development of third and fourth instar larvae fed on diet supplemented with rapamycin, in order to better understand the role of the TOR pathway in larval growth. When rapamycin was added to the diet of larvae, the onset of molting was delayed, the growth rate was reduced and abnormally small larvae/pupae with high mortality rates resulted. In larvae fed on diet supplemented with rapamycin, the growth of PGs was suppressed, and ecdysone production and secretion were inhibited. Overall, the in vivo and in vitro results demonstrated that, similarly to Bombyx mori, MAPK and PI3K/Akt/TOR pathways are involved in PTTH signaling-stimulated ecdysteroidogenesis, and indicated the important role of TOR protein in H. virescens systemic growth. Copyright © 2018 Elsevier Ltd. All rights reserved.

“Heliobase” - Jumpstarting Heliothine Genomics

USDA-ARS?s Scientific Manuscript database

Heliothine moths are major polyphagous pests of commodity crops such as maize, cotton, soybeans and vegetables throughout the world. Control of larvae of the North American pest moth Heliothis virescens, also known as the budworm, and other closely related heliothines would be fundamentally advance...

Interspecific pheromone plume interference among sympatric heliothine moths: a wind tunnel test using live, calling females.

PubMed

Lelito, Jonathan P; Myrick, Andrew J; Baker, Thomas C

2008-06-01

Three species of North American heliothine moths were used to determine the level at which interspecific female interference of male attraction to conspecific females occurs. We used live calling females of Heliothis virescens, H. subflexa, and Helicoverpa zea, as lures for conspecific males in a wind tunnel, and then placed heterospecific females on either side of the original species such that the plumes of the three females overlapped downwind. In nearly all combinations, in the presence of heterospecific females, fewer males flew upwind and contacted or courted the source than when only conspecific females were used in the same spatial arrangement. Males did not initiate upwind flight to solely heterospecific female arrangements. Our results show that the naturally emitted pheromone plumes from heterospecific females of these three species can interfere with the ability of females to attract conspecific males when multiple females are in close proximity. However, the fact that some males still located their calling, conspecific females attests to the ability of these male moths to discriminate point source odors by processing the conflicting information from interleaved strands of attractive and antagonistic odor filaments on a split-second basis.

Chlorophyll degradation in the gut of generalist and specialist Lepidopteran caterpillars.

PubMed

Badgaa, Amarsanaa; Jia, Aiqun; Ploss, Kerstin; Boland, Wilhelm

2014-12-01

Plant feeding herbivores excrete most of the ingested chlorophyll (Chl) as partly degraded derivatives lacking the phytol side chain and the central magnesium ion. An ecological role of digested and degraded Chls in the interactions between insects, their food plant and other insects has been described recently. To gain more information on common degradation patterns in plant-feeding insects, the orals secretions and frass of five Lepidopteran caterpillars covering generalists and specialists, namely Spodoptera littoralis, Spodoptera eridania, Heliothis virescens, Helicoverpa armigera, Manduca sexta, and, for comparison, of the leaf beetle larva Chrysomela lapponica were analyzed for chlorophyll catabolites. The major degradation products were determined as pheohorbide a/b and pyropheophorbide a/b by using LC-MS, LC-NMR, UV, and fluorescence spectrometry. The compounds were not present in fresh leaves of the food plants (Phaseolus lunatus, Nicotiana tabacum). The catabolite spectrum in generalists and specialists was qualitatively similar and could be attributed to the action of gut proteins and the strongly alkaline milieu in the digestive tract. Due to the anaerobic environment of the larval gut, the tetrapyrrole core of the Chl catabolites was not cleaved. Substantial amounts of Chl a/b metabolites were strongly complexed by a protein in the mid-gut.

Dynamics of transcriptomic response to infection by the nematode Heterorhabditis bacteriophora and its bacterial symbiont Photorhabdus temperata in Heliothis virescens larvae.

PubMed

An, R; Suri, K S; Jurat-Fuentes, J L; Grewal, P S

2017-10-01

Entomopathogenic nematodes in the Heterorhabditis genus and their symbiotic Photorhabdus bacteria are important biocontrol agents of insect pests and models for the study of microbe-host interactions. In this work, we used larvae of the tobacco budworm (Heliothis virescens) as a model to study its defensive mechanisms against Heterorhabditis bacteriophora nematodes carrying symbiotic Photorhabdus temperata. We first determined time points of initial nematode entry and release of bacteria into the haemolymph to perform transcriptional analysis of insect gene expression during these steps in the infective process. RNA-Sequencing analyses were then performed to profile differential gene expression in the insect during nematode invasion, bacterial release and final steps of infection, relative to the untreated controls. Our results support the theory that insect immune response genes are induced upon nematode invasion, but the majority of these genes are suppressed upon the release of bacteria by the nematodes into the haemolymph. Overall, these findings provide information on the dynamics of the insect's response to a progressing infection by this entomopathogenic nematode-bacteria complex and facilitate development of Hel. virescens as a pest model for future functional studies of the key insect defence factors. © 2017 The Royal Entomological Society.

Sub-lethal effects of Vip3A toxin on survival, development and fecundity of Heliothis virescens and Plutella xylostella.

PubMed

Gulzar, Asim; Wright, Denis J

2015-11-01

The assessment of sub-lethal effects is important to interpret the overall insecticide efficacy in controlling insect pest populations. In addition to the lethal effect, sub-lethal effects may also occur in exposed insects. Vegetative insecticidal proteins (Vips) have shown a broad spectrum of insecticidal activity against many insect pest species. In this study the sub-lethal effects of the Bacillus thuringiensis vegetative insecticidal toxin Vip3A on the development and reproduction of Heliothis virescens F. and Plutella xylostella L. were evaluated in the laboratory. The results indicated that the sub-lethal concentration of Vip3A increased the duration of the larval and pupal stages as compared with the control treatment for both species. The percent pupation and percent adult emergence were significantly lower for Vip3A-treated insects. The proportion of pairs that produced eggs and the longevity of adults were not significantly different between treatments. H. virescens and P. xylostella treated with Vip3A showed an 11 and 17 % decrease in their intrinsic rate of increase (rm) respectively compared with untreated insects. The results from this study will be helpful to develop the strategy to incorporate Vip 3A containing crops in an integrated pest management programme.

Variability of Bacterial Communities in the Moth Heliothis virescens Indicates Transient Association with the Host

PubMed Central

Staudacher, Heike; Kaltenpoth, Martin; Breeuwer, Johannes A. J.; Menken, Steph B. J.; Heckel, David G.; Groot, Astrid T.

2016-01-01

Microbes associated with insects can confer a wide range of ecologically relevant benefits to their hosts. Since insect-associated bacteria often increase the nutritive value of their hosts' diets, the study of bacterial communities is especially interesting in species that are important agricultural pests. We investigated the composition of bacterial communities in the noctuid moth Heliothis virescens and its variability in relation to developmental stage, diet and population (field and laboratory), using bacterial tag-encoded FLX pyrosequencing of 16S rRNA amplicons. In larvae, bacterial communities differed depending on the food plant on which they had been reared, although the within-group variation between biological replicates was high as well. Moreover, larvae originating from a field or laboratory population did not share any OTUs. Interestingly, Enterococcus sp. was found to be the dominant taxon in laboratory-reared larvae, but was completely absent from field larvae, indicating dramatic shifts in microbial community profiles upon cultivation of the moths in the laboratory. Furthermore, microbiota composition varied strongly across developmental stages in individuals of the field population, and we found no evidence for vertical transmission of bacteria from mothers to offspring. Since sample sizes in our study were small due to pooling of samples for sequencing, we cautiously conclude that the high variability in bacterial communities suggests a loose and temporary association of the identified bacteria with H. virescens. PMID:27139886

Systemic Imidacloprid Affects Intraguild Parasitoids Differently

PubMed Central

Roe, R. Michael; Bacheler, Jack S.

2015-01-01

Toxoneuron nigriceps (Viereck) (Hymenoptera, Braconidae) and Campoletis sonorensis (Cameron) (Hymenoptera, Ichneumonidae) are solitary endoparasitoids of the tobacco budworm, Heliothis virescens (Fabricius) (Lepidoptera, Noctuidae). They provide biological control of H. virescens populations in Southeastern US agricultural production systems. Field and greenhouse experiments conducted from 2011–2014 compared parasitism rates of parasitoids that developed inside H. virescens larvae fed on tobacco plants treated with and without imidacloprid. The parasitoids in our study did not have a similar response. Toxoneuron nigriceps had reduced parasitism rates, but parasitism rates of C. sonorensis were unaffected. Preliminary data indicate that adult female lifespans of T. nigriceps are also reduced. ELISA was used to measure concentrations of neonicotinoids, imidacloprid and imidacloprid metabolites in H. virescens larvae that fed on imidacloprid-treated plants and in the parasitoids that fed on these larvae. Concentrations were detectable in the whole bodies of parasitized H. virescens larvae, T. nigriceps larvae and T. nigriceps adults, but not in C. sonorensis larvae and adults. These findings suggest that there are effects of imidacloprid on multiple trophic levels, and that insecticide use may differentially affect natural enemies with similar feeding niches. PMID:26658677

Measurement of Trace Elements During the Development and Immune Response of Heliothis virescens Larvae

USDA-ARS?s Scientific Manuscript database

While many studies have examined the effect of microbial infections on the status of trace elements in mammalian tissues, similar studies have not been performed in insects. We used inductively coupled plasma-mass spectrometry (ICP-MS) to quantify changes in trace elements of Mg, Mn, Fe, Cu, Zn and ...

Resistance monitoring of Heliothis virescens to pyramided cotton varieties with a hydrateable, artificial cotton leaf bioassay

USDA-ARS?s Scientific Manuscript database

Proof of concept was demonstrated for a practical, off the shelf bioassay to monitor for tobacco budworm resistance to pyramided Bt cotton using plant eluants. The bioassay was based on a previously described feeding disruption test using hydrateable artificial diet containing a blue indicator dye, ...

Competitive release as an ecological cause of stink bug outbreaks in transgenic Bt cotton in the southeast US

USDA-ARS?s Scientific Manuscript database

Insect-resistant transgenic Bt cotton has, in general, increased yield and reduced insecticide use in cotton production by successfully managing target pests. In the southeast US, Bt cotton provides effective control of Helicpverpa zea and Heliothis virescens [Lepidoptera: Noctuidae]. However Bt c...

Effects of 1,1-Dimethylpiperidinium Chloride on the Pests and Allelochemicals of Cotton and Pecan.

Treesearch

P. A. Hedin; J. N. Jenkins; J. C. McCarty; J. E. Mulrooney; W. L. Parrott; A. Borazjani; C. H. Graves; T. H. Filer

1984-01-01

The growth regulator, PIX (mepiquat chloride - 1,1-dimethyl-piperdinium chloride), when applied to cotton (Gossypium hirsutum L.) and pecan (Carya illinoensis Koch), caused internode shortening. PIX did not elicit an increase in resistance in cotton to the tobacco budworm (Heliothis virescens (Fab.)], or in pecan...

Arylphorin is a mitogen in the Heliothis virescens midgut cell secretome upon Cry1Ac intoxication

USDA-ARS?s Scientific Manuscript database

Insecticidal crystal (Cry) proteins produced by the bacterium Bacillus thuringiensis (Bt) target cells in the midgut epithelium of susceptible larvae. While the mode of action of Cry toxins has been extensively investigated, the midgut response to Cry intoxication and its regulation are not well ch...

Insect Larvae: A New Platform to Produce Commercial Recombinant Proteins.

PubMed

Targovnik, Alexandra M; Arregui, Mariana B; Bracco, Lautaro F; Urtasun, Nicolas; Baieli, Maria F; Segura, Maria M; Simonella, Maria A; Fogar, Mariela; Wolman, Federico J; Cascone, Osvaldo; Miranda, Maria V

2016-01-01

In Biotechnology, the expression of recombinant proteins is a constantly growing field and different hosts are used for this purpose. Some valuable proteins cannot be produced using traditional systems. Insects from the order Lepidoptera infected with recombinant baculovirus have appeared as a good choice to express high levels of proteins, especially those with post-translational modifications. Lepidopteran insects, which are extensively distributed in the world, can be used as small protein factories, the new biofactories. Species like Bombyx mori (silkworm) have been analyzed in Asian countries to produce a great number of recombinant proteins for use in basic and applied science and industry. Many proteins expressed in this larva have been commercialized. Several recombinant proteins produced in silkworms have already been commercialized. On the other hand, species like Spodoptera frugiperda, Heliothis virescens, Rachiplusia nu, Helicoverpa zea and Trichoplusia ni are widely distributed in both the occidental world and Europe. The expression of recombinant proteins in larvae has the advantage of its low cost in comparison with insect cell cultures. A wide variety of recombinant proteins, including enzymes, hormones and vaccines, have been efficiently expressed with intact biological activity. The expression of pharmaceutically proteins, using insect larvae or cocoons, has become very attractive. This review describes the use of insect larvae as an alternative to produce commercial recombinant proteins.

Genomic sequence of Heliothis virescens ascovirus 3g isolated from Spodoptera exigua.

PubMed

Huang, Guo-Hua; Wang, Yun-Sheng; Wang, Xing; Garretson, Tyler A; Dai, Liang-Ying; Zhang, Chuan-Xi; Cheng, Xiao-Wen

2012-11-01

Heliothis virescens ascovirus 3a (HvAV-3a), a member of the family Ascoviridae, has the highest diversity among ascovirus species that have been reported in Australia, Indonesia, China, and the United States. To understand the diversity and origin of this important ascovirus, the complete genome of the HvAV Indonesia strain (HvAV-3g), isolated from Spodoptera exigua, was determined to be 199,721 bp, with a G+C content of 45.9%. Therefore, HvAV-3g has the largest genome among the reported ascovirus genomes to date. There are 194 predicted open reading frames (ORFs) encoding proteins of 50 or more amino acid residues. In comparison to HvAV-3e reported from Australia, HvAV-3g has all the ORFs in HvAV-3e with 6 additional ORFs unique to HvAV-3g, including 1 peptidase C26 gene with the highest identity to Drosophila spp. and 2 gas vesicle protein U (GvpU) genes with identities to Bacillus megaterium. The five unique homologous regions (hrs) and 25 baculovirus repeat ORFs (bro) of HvAV-3g are highly variable.

Indirect multi-trophic interactions mediated by induced plant resistance: impact of caterpillar feeding on aphid parasitoids

PubMed Central

Hagenbucher, Steffen; Wäckers, Felix L.; Romeis, Jörg

2014-01-01

Cotton produces insecticidal terpenoids that are induced by tissue-feeding herbivores. Damage by Heliothis virescens caterpillars increases the terpenoid content, which reduces the abundance of aphids. This effect is not evident in Bt-transgenic cotton, which is resistant to H. virescens. We determined whether induction of terpenoids by caterpillars influences the host quality of Aphis gossypii for the parasitoid Lysiphlebus testaceipes and whether this interaction is influenced by Bt cotton. The exposure of parasitoids to terpenoids was determined by quantifying terpenoids in the aphids. We detected several terpenoids in aphids and found a positive relationship between their concentrations in plants and aphids. When L. testaceipes was allowed to parasitize aphids on Bt and non-Bt cotton that was infested or uninfested with H. virescens, fewer parasitoid mummies were found on infested non-Bt than on Bt cotton. Important parasitoid life-table parameters, however, were not influenced by induced resistance following H. virescens infestation, or the Bt trait. Our study provides an example of a tritrophic indirect interaction web, where organisms are indirectly linked through changes in plant metabolites. PMID:24522627

Autographa californica multiple nucleopolyhedrovirus ODV-E56 is a per os infectivity factor, but is not essential for binding and fusion of occlusion-derived virus to the host midgut

USDA-ARS?s Scientific Manuscript database

The Autographa californica multiple nucleopolyhedrovirus (AcMNPV) occlusion-derived virus (ODV) envelope protein ODV-E56 is essential for oral infection of neonate Heliothis virescens larvae. Here, we present a more detailed study of ODV-E56 function. Bioassays with recombinant clones of AcMNPV lack...

Species From the Heliothinae Complex (Lepidoptera: Noctuidae) in Tucumán, Argentina, an Update of Geographical Distribution of Helicoverpa armigera

PubMed Central

Murúa, M. Gabriela; Cazado, Lucas E.; Casmuz, Augusto; Herrero, M. Inés; Villagrán, M. Elvira; Vera, Alejandro; Sosa-Gómez, Daniel R.; Gastaminza, Gerardo

2016-01-01

The Heliothinae complex in Argentina encompasses Helicoverpa gelotopoeon (Dyar), Helicoverpa zea (Boddie), Helicoverpa armigera (Hübner), and Chloridea virescens (Fabricius). In Tucumán, the native species H. gelotopoeon is one of the most voracious soybean pests and also affects cotton and chickpea, even more in soybean-chickpea succession cropping systems. Differentiation of the Heliothinae complex in the egg, larva, and pupa stages is difficult. Therefore, the observation of the adult wing pattern design and male genitalia is useful to differentiate species. The objective of this study was to identify the species of the Heliothinae complex, determine population fluctuations of the Heliothinae complex in soybean and chickpea crops using male moths collected in pheromone traps in Tucuman province, and update the geographical distribution of H. armigera in Argentina. The species found were H. gelotopoeon, H. armigera, H. zea, and C. virescens. Regardless of province, county, crop, and year, the predominant species was H. gelotopoeon. Considering the population dynamics of H. gelotopoeon and H. armigera in chickpea and soybean crops, H. gelotopoeon was the most abundant species in both crops, in all years sampled, and the differences registered were significant. On the other hand, according to the Sistema Nacional Argentino de Vigilancia y Monitoreo de Plagas (SINAVIMO) database and our collections, H. armigera was recorded in eight provinces and 20 counties of Argentina, and its larvae were found on soybean, chickpea, sunflower crops and spiny plumeless thistle (Carduus acanthoides). This is the first report of H. armigera in sunflower and spiny plumeless thistle in Argentina. PMID:27324588

Quantification of larval resistance to Cypermethrin in tobacco budworm (Lepidoptera: Noctuidae) and the effects of larval weight

Treesearch

Michael J. Firko; Janes Leslie Hayes

1990-01-01

We examined relationships between larval weight and degree of resistance to cypermethrin in tobacco budworm, Heliothis virescens (F.). Laboratory-reared larvae (9.0-175.4 mg) were treated with either 0.1 or 1.0 mg cypermethrin in acetone. Degree of debilitation of each larva was assessed at intervals from 0.5 h to 5 d after treatment cumulative...

Species From the Heliothinae Complex (Lepidoptera: Noctuidae) in Tucumán, Argentina, an Update of Geographical Distribution of Helicoverpa armigera.

PubMed

Murúa, M Gabriela; Cazado, Lucas E; Casmuz, Augusto; Herrero, M Inés; Villagrán, M Elvira; Vera, Alejandro; Sosa-Gómez, Daniel R; Gastaminza, Gerardo

2016-01-01

The Heliothinae complex in Argentina encompasses Helicoverpa gelotopoeon (Dyar), Helicoverpa zea (Boddie), Helicoverpa armigera (Hübner), and Chloridea virescens (Fabricius). In Tucumán, the native species H. gelotopoeon is one of the most voracious soybean pests and also affects cotton and chickpea, even more in soybean-chickpea succession cropping systems. Differentiation of the Heliothinae complex in the egg, larva, and pupa stages is difficult. Therefore, the observation of the adult wing pattern design and male genitalia is useful to differentiate species. The objective of this study was to identify the species of the Heliothinae complex, determine population fluctuations of the Heliothinae complex in soybean and chickpea crops using male moths collected in pheromone traps in Tucuman province, and update the geographical distribution of H. armigera in Argentina. The species found were H. gelotopoeon, H. armigera, H. zea, and C. virescens. Regardless of province, county, crop, and year, the predominant species was H. gelotopoeon Considering the population dynamics of H. gelotopoeon and H. armigera in chickpea and soybean crops, H. gelotopoeon was the most abundant species in both crops, in all years sampled, and the differences registered were significant. On the other hand, according to the Sistema Nacional Argentino de Vigilancia y Monitoreo de Plagas (SINAVIMO) database and our collections, H. armigera was recorded in eight provinces and 20 counties of Argentina, and its larvae were found on soybean, chickpea, sunflower crops and spiny plumeless thistle (Carduus acanthoides). This is the first report of H. armigera in sunflower and spiny plumeless thistle in Argentina. © The Author 2016. Published by Oxford University Press on behalf of the Entomological Society of America.

Overexpression of the Bacillus thuringiensis (Bt) Cry2Aa2 protein in chloroplasts confers resistance to plants against susceptible and Bt-resistant insects

PubMed Central

Kota, Madhuri; Daniell, Henry; Varma, Sam; Garczynski, Stephen F.; Gould, Fred; Moar, William J.

1999-01-01

Evolving levels of resistance in insects to the bioinsecticide Bacillus thuringiensis (Bt) can be dramatically reduced through the genetic engineering of chloroplasts in plants. When transgenic tobacco leaves expressing Cry2Aa2 protoxin in chloroplasts were fed to susceptible, Cry1A-resistant (20,000- to 40,000-fold) and Cry2Aa2-resistant (330- to 393-fold) tobacco budworm Heliothis virescens, cotton bollworm Helicoverpa zea, and the beet armyworm Spodoptera exigua, 100% mortality was observed against all insect species and strains. Cry2Aa2 was chosen for this study because of its toxicity to many economically important insect pests, relatively low levels of cross-resistance against Cry1A-resistant insects, and its expression as a protoxin instead of a toxin because of its relatively small size (65 kDa). Southern blot analysis confirmed stable integration of cry2Aa2 into all of the chloroplast genomes (5,000–10,000 copies per cell) of transgenic plants. Transformed tobacco leaves expressed Cry2Aa2 protoxin at levels between 2% and 3% of total soluble protein, 20- to 30-fold higher levels than current commercial nuclear transgenic plants. These results suggest that plants expressing high levels of a nonhomologous Bt protein should be able to overcome or at the very least, significantly delay, broad spectrum Bt-resistance development in the field. PMID:10051556

Plant odorants interfere with detection of sex pheromone signals by male Heliothis virescens

PubMed Central

Pregitzer, Pablo; Schubert, Marco; Breer, Heinz; Hansson, Bill S.; Sachse, Silke; Krieger, Jürgen

2012-01-01

In many insects, mate finding relies on female-released sex pheromones, which have to be deciphered by the male olfactory system within an odorous background of plant volatiles present in the environment of a calling female. With respect to pheromone-mediated mate localization, plant odorants may be neutral, favorable, or disturbing. Here we examined the impact of plant odorants on detection and coding of the major sex pheromone component, (Z)-11-hexadecenal (Z11-16:Ald) in the noctuid moth Heliothis virescens. By in vivo imaging the activity in the male antennal lobe (AL), we monitored the interference at the level of olfactory sensory neurons (OSN) to illuminate mixture interactions. The results show that stimulating the male antenna with Z11-16:Ald and distinct plant-related odorants simultaneously suppressed pheromone-evoked activity in the region of the macroglomerular complex (MGC), where Z11-16:Ald-specific OSNs terminate. Based on our previous findings that antennal detection of Z11-16:Ald involves an interplay of the pheromone binding protein (PBP) HvirPBP2 and the pheromone receptor (PR) HR13, we asked if the plant odorants may interfere with any of the elements involved in pheromone detection. Using a competitive fluorescence binding assay, we found that the plant odorants neither bind to HvirPBP2 nor affect the binding of Z11-16:Ald to the protein. However, imaging experiments analyzing a cell line that expressed the receptor HR13 revealed that plant odorants significantly inhibited the Z11-16:Ald-evoked calcium responses. Together the results indicate that plant odorants can interfere with the signaling process of the major sex pheromone component at the receptor level. Consequently, it can be assumed that plant odorants in the environment may reduce the firing activity of pheromone-specific OSNs in H. virescens and thus affect mate localization. PMID:23060749

Sugar Diet Affects Odor Reception but Variation in Sugar Concentration Plays Minimal Role in the Response of the Parasitoid, Microplitis croceipes (Hymenoptera: Braconidae), to Host-Related Plant Volatiles.

PubMed

Burrows, Matthew; Morawo, Tolulope; Fadamiro, Henry

2017-06-01

Parasitoids utilize various sugar resources in nature, and rely on odor cues from plants to locate their food and hosts. However, lack of sugar in the diet may negatively impact odor reception in parasitoids, thus affecting foraging efficiency. We used Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), a larval endoparasitoid of Heliothis virescens (F.) (Lepidoptera: Noctuidae), as a model species to test the hypothesis that variation in sugar diet of parasitoids affects their olfactory response to host-related odors. Heliothis virescens is a major pest of cotton and other important crops. Response of female M. croceipes fed different diet treatments (i.e., 40%, 20%, 10%, or 0% sucrose/water solution [w/v]) to select cotton volatiles were tested in electroantennogram (EAG) and Y-tube olfactometer bioassays. The following cotton plant odors were tested: cis-3-hexenol, α-pinene, 50/50 v/v binary mixture of cis-3-hexenol and α-pinene, and H. virescens-infested cotton. Sucrose-fed parasitoids showed higher EAG response to the binary mixture and host-infested plant volatile extract, compared with sucrose-starved (0% sucrose) parasitoids. However, there was no significant difference in EAG response of parasitoids to odor treatments among individuals fed 40%, 20%, or 10% sucrose. In a Y-tube olfactometer, female M. croceipes fed 40% sucrose were significantly more attracted to host-infested cotton than to a control (no plant). However, parasitoids were not significantly attracted to other odor stimuli. These results suggest that the availability of sugar diet affects odor reception in M. croceipes but variation in sugar concentration probably plays a minimal role in olfactory response of M. croceipes to host-related odors. © 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.

Suitability of Invertebrate and Vertebrate Cells in a Portable Impedance-Based Toxicity Sensor: Temperature Mediated Impacts on Long-Term Survival

DTIC Science & Technology

2013-07-25

ovary cells from Spodoptera frugiperda ATCCa CRL-1711 Grace VA) (Vaughn et al., 1977) HvAM1: pupal ovary cells from Heliothis virescens Dr. C Goodman...iguana. Ecology 78, 297–307. Vaughn, J.L., Goodwind, R.H., Tompkins, G.J., McCawley, P., 1977. Establishment of 2 cell lines from insect Spodoptera ... frugiperda . In Vitro 13, 213–217. Wilson, S.M., Nagler, J.J., 2006. Age, but not salinity, affects the upper lethal temperature limits for juvenile

Survival and development of Heliothis virescens (Lepidoptera: Noctuidae) larvae on isogenic tobacco lines with different levels of alkaloids.

PubMed

Jackson, D Michael; Johnson, A W; Stephenson, M G

2002-12-01

Levels of pyridine alkaloids were measured in 18 tobacco, Nicotiana tabacum L., entries from three parental isolines ('NC 95', 'SC 58', and 'Coker 139'), grown at Tifton, GA, Florence, SC, and Oxford, NC, in 1991. Levels of alkaloids in bud leaves (first fully unfolded leaf below the apical leaf bud) were negatively correlated to natural infestation ratings of tobacco budworm larvae, Heliothis virescens (F.), 7 wk after transplanting. For artificially infested bud leaves at Oxford, there was a significant negative correlation between levels of total alkaloids and larval weights after 1 wk of feeding. In 1992, four entries from the 'NC 95' isoline were grown at Oxford, and samples for alkaloid analyses were taken every 2 wk at several leaf positions on each plant. During weeks 4, 8, 12, and 16, second instar tobacco budworms were caged on individual, intact leaves inside perforated plastic bags in the field. The survival and development of tobacco budworm larvae after 1 wk were negatively correlated with levels of alkaloids at the various leaf positions. Larvae survived better and grew faster on the bud leaves of each entry where alkaloid levels were lower than they did on leaves further down the stalk where alkaloid levels were higher. More larvae survived on the lower leaves of the low alkaloid lines than on the lower leaves of the high alkaloid lines. Even moderate increases in pyridine alkaloids had negative effects on tobacco budworm survival and development. Nicotine constituted >97% of the pyridine alkaloids in the 'NC95' isoline each year.

Effects of Vegetated Field Borders on Arthropods in Cotton Fields in Eastern North Carolina

PubMed Central

Outward, Randy; Sorenson, Clyde E.; Bradley, J. R.

2008-01-01

The influence, if any, of 5m wide, feral, herbaceous field borders on pest and beneficial arthropods in commercial cotton, Gossypium hirsutum (L.) (Malvales: Malvaceae), fields was measured through a variety of sampling techniques over three years. In each year, 5 fields with managed, feral vegetation borders and five fields without such borders were examined. Sampling was stratified from the field border or edge in each field in an attempt to elucidate any edge effects that might have occurred. Early season thrips populations appeared to be unaffected by the presence of a border. Pitfall sampling disclosed no differences in ground-dwelling predaceous arthropods but did detect increased populations of crickets around fields with borders. Cotton aphid (Aphis gossypii Glover) (Hemiptera: Aphididae) populations were too low during the study to adequately assess border effects. Heliothines, Heliothis virescens (F.) and Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), egg numbers and damage rates were largely unaffected by the presence or absence of a border, although in one instance egg numbers were significantly lower in fields with borders. Overall, foliage-dwelling predaceous arthropods were somewhat more abundant in fields with borders than in fields without borders. Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae) were significantly more abundant in fields with borders, but stink bugs, Acrosternum hilare (Say), and Euschistus servus (Say) (Hemiptera: Pentatomidae) numbers appeared to be largely unaffected by border treatment. Few taxa clearly exhibited distributional edge effects relative to the presence or absence of border vegetation. Field borders like those examined in this study likely will have little impact on insect pest management in cotton under current insect management regimens. PMID:20345293

Re-Evaluation of the PBAN Receptor Molecule: Characterization of PBANR Variants Expressed in the Pheromone Glands of Moths

PubMed Central

Lee, Jae Min; Hull, J. Joe; Kawai, Takeshi; Goto, Chie; Kurihara, Masaaki; Tanokura, Masaru; Nagata, Koji; Nagasawa, Hiromichi; Matsumoto, Shogo

2011-01-01

Sex pheromone production in most moths is initiated following pheromone biosynthesis activating neuropeptide receptor (PBANR) activation. PBANR was initially cloned from pheromone glands (PGs) of Helicoverpa zea and Bombyx mori. The B. mori PBANR is characterized by a relatively long C-terminus that is essential for ligand-induced internalization, whereas the H. zea PBANR has a shorter C-terminus that lacks features present in the B. mori PBANR critical for internalization. Multiple PBANRs have been reported to be concurrently expressed in the larval CNS of Heliothis virescens. In the current study, we sought to examine the prevalence of multiple PBANRs in the PGs of three moths and to ascertain their potential functional relevance. Multiple PBANR variants (As, A, B, and C) were cloned from the PGs of all species examined with PBANR-C the most highly expressed. Alternative splicing of the C-terminal coding sequence of the PBAN gene gives rise to the variants, which are distinguishable only by the length and composition of their respective C-terminal tails. Transient expression of fluorescent PBANR chimeras in insect cells revealed that PBANR-B and PBANR-C localized exclusively to the cell surface while PBANR-As and PBANR-A exhibited varying degrees of cytosolic localization. Similarly, only the PBANR-B and PBANR-C variants underwent ligand-induced internalization. Taken together, our results suggest that PBANR-C is the principal receptor molecule involved in PBAN signaling regardless of moth species. The high GC content of the C-terminal coding sequence in the B and C variants, which makes amplification using conventional polymerases difficult, likely accounts for previous “preferential” amplification of PBANR-A like receptors from other species. PMID:22654850

Diet micronutrient balance matters: How the ratio of dietary sterols/steroids affects development, growth and reproduction in two lepidopteran insects.

PubMed

Jing, Xiangfeng; Grebenok, Robert J; Behmer, Spencer T

2014-08-01

Insects lack the ability to synthesize sterols de novo so they acquire this essential nutrient from their food. Cholesterol is the dominant sterol found in most insects, but in plant vegetative tissue it makes up only a small fraction of the total sterol profile. Instead, plants mostly contain phytosterols; plant-feeding insects generate the majority of their cholesterol by metabolizing phytosterols. However, not all phytosterols are readily converted to cholesterol, and some are even deleterious when ingested above a threshold level. In a recent study we showed that caterpillars reared on tobacco accumulating novel sterols/steroids exhibited reduced performance, even when suitable sterols were present. In the current study we examined how the dominant sterols (cholesterol and stigmasterol) and steroids (cholestanol and cholestanone) typical of the modified tobacco plants affected two insect herbivores (Heliothis virescens and Helicoverpa zea). The sterols/steroids were incorporated into synthetic diets singly, as well as in various combinations, ratios and amounts. For each insect species, a range of performance values was recorded for two generations, with the eggs from the 1st-generation adults as the source of neonates for the 2nd-generation. Performance on the novel steroids (cholestanol and cholestanone) was extremely poor compared to suitable sterols (cholesterol and stigmasterol). Additionally, performance tended to decrease as the ratio of the novel dietary steroids increased. We discuss how the balance of different dietary sterols/steroids affected our two caterpillar species, relate this back to recent studies on sterol/steroid metabolism in these two species, and consider the potential application of sterol/steroid modification in crops. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synergism and Antagonism between Bacillus thuringiensis Vip3A and Cry1 Proteins in Heliothis virescens, Diatraea saccharalis and Spodoptera frugiperda

PubMed Central

Lemes, Ana Rita Nunes; Davolos, Camila Chiaradia; Legori, Paula Cristina Brunini Crialesi; Fernandes, Odair Aparecido; Ferré, Juan; Lemos, Manoel Victor Franco; Desiderio, Janete Apparecida

2014-01-01

Second generation Bt crops (insect resistant crops carrying Bacillus thuringiensis genes) combine more than one gene that codes for insecticidal proteins in the same plant to provide better control of agricultural pests. Some of the new combinations involve co-expression of cry and vip genes. Because Cry and Vip proteins have different midgut targets and possibly different mechanisms of toxicity, it is important to evaluate possible synergistic or antagonistic interactions between these two classes of toxins. Three members of the Cry1 class of proteins and three from the Vip3A class were tested against Heliothis virescens for possible interactions. At the level of LC50, Cry1Ac was the most active protein, whereas the rest of proteins tested were similarly active. However, at the level of LC90, Cry1Aa and Cry1Ca were the least active proteins, and Cry1Ac and Vip3A proteins were not significantly different. Under the experimental conditions used in this study, we found an antagonistic effect of Cry1Ca with the three Vip3A proteins. The interaction between Cry1Ca and Vip3Aa was also tested on two other species of Lepidoptera. Whereas antagonism was observed in Spodoptera frugiperda, synergism was found in Diatraea saccharalis. In all cases, the interaction between Vip3A and Cry1 proteins was more evident at the LC90 level than at the LC50 level. The fact that the same combination of proteins may result in a synergistic or an antagonistic interaction may be an indication that there are different types of interactions within the host, depending on the insect species tested. PMID:25275646

Molecular elements of pheromone detection in the female moth, Heliothis virescens.

PubMed

Zielonka, Monika; Breer, Heinz; Krieger, Jürgen

2018-06-01

Pheromones play pivotal roles in the reproductive behavior of moths, most prominently for the mate finding of male moths. Accordingly, the molecular basis for the detection of female-released pheromones by male moths has been studied in great detail. In contrast, little is known about how females can detect pheromone components released by themselves or by conspecifics. In this study, we assessed the antenna of female Heliothis virescens for elements of pheromone detection. In accordance with previous findings that female antennae respond to the sex pheromone component (Z)-9-tetradecenal, we identified olfactory sensory neurons that express its cognate receptor, the receptor type HR6. All HR6 cells coexpressed the "sensory neuron membrane protein 1" (SNMP1) and were associated with supporting cells expressing the pheromone-binding proteins PBP1 and PBP2. These features are reminiscent to male antennae and point to congruent mechanisms for pheromone detection in the two sexes. Further analysis of the SNMP1-expressing cells revealed a higher number in females compared to males. Moreover, in females, the SNMP1 neurons were arranged in clusters, which project their dendrites into a common sensillum, whereas in males there were only solitary SNMP1-neurons and only 1 per sensillum. Not all SNMP1 positive cells in female antennae expressed HR6 but instead the putative pheromone receptors HR11 and HR18, respectively. Neurons expressing 1 of the 3 receptor types were assigned to different sensilla. Together the data indicate that on the antenna of females, sensory neurons in a subset of sensilla trichodea are equipped with molecular elements, which render them responsive to pheromones. © 2016 Institute of Zoology, Chinese Academy of Sciences.

Effects of immune challenge on the oviposition strategy of a noctuid moth.

PubMed

Staudacher, H; Menken, S B J; Groot, A T

2015-08-01

Infections can have detrimental effects on the fitness of an animal. Reproducing females may therefore be sensitive to cues of infection and be able to adaptively change their oviposition strategy in the face of infection. As one possibility, females could make a terminal investment and shift reproductive effort from future to current reproduction as life expectancy decreases. We hypothesized that females of the noctuid moth Heliothis virescens make a terminal investment and adapt their oviposition timing as well as their oviposition site selectivity in response to an immune challenge. We indeed found that females that were challenged with the bacterial entomopathogen Serratia entomophila laid more eggs than control females one night after the challenge. Additionally, bacteria-challenged females were less discriminating between oviposition sites than control females. Whereas control females preferred undamaged over damaged plants, immune-challenged females did not differentiate between the two. These results indicate that terminal investment is part of the life history of H. virescens females. Moreover, our results suggest that the strategy of terminal investment in H. virescens oviposition represents a fitness trade-off for females: in the face of infection, an increase in oviposition rate enhances female fitness, whereas low oviposition site selectivity reduces female fitness. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

Duration of plant damage by host larvae affects attraction of two parasitoid species (Microplitis croceipes and Cotesia marginiventris) to cotton: implications for interspecific competition.

PubMed

Morawo, Tolulope; Fadamiro, Henry

2014-12-01

Volatile organic compounds (VOCs) released by herbivore-damaged plants can guide parasitoids to their hosts. The quantity and quality of VOC blends emitted by plants may be affected by the duration of plant damage by herbivores, which could have potential ramifications on the recruitment of competing parasitoids. We used two parasitoid species, Microplitis croceipes and Cotesia marginiventris (Hymenoptera: Braconidae), to address the question of whether duration of plant damage affects parasitoid use of plant VOCs for host location. Both wasp species are larval endoparasitoids of Heliothis virescens (Lepidoptera: Noctuidae), an important pest of cotton. Attraction of the two parasitoid species to odors emitted by undamaged (UD), fresh (6 h infestation) damage (FD), and old (24 h infestation) damage (OD) cotton plants infested by H. virescens larvae was investigated using a headspace volatile collection system coupled with four-choice olfactometer bioassay. Both sexes of M. croceipes showed a preference for FD- and OD-plant odors over UD-plants. On the other hand, more C. marginiventris females were attracted to UD- and FD-plants than to OD-plants. GC/MS analyses showed qualitative and quantitative differences in the VOC profiles of UD, FD, and OD-plants, which may explain the observed preferences of the parasitoids. These results suggest a temporal partitioning in the recruitment of M. croceipes and C. marginiventris to H. virescens-damaged cotton, and may have potential implications for interspecific competition between the two parasitoid species.

Sex pheromone in the moth Heliothis virescens is produced as a mixture of two pools: de novo and via precursor storage in glycerolipids.

PubMed

Foster, Stephen P; Anderson, Karin G; Casas, Jérôme

2017-08-01

Most species of moths use a female-produced volatile sex pheromone, typically produced via de novo fatty acid synthesis in a specialized gland, for communication among mates. While de novo biosynthesis of pheromone (DNP) is rapid, suggesting transient precursor acids, substantial amounts of pheromone precursor (and other) acids are stored, predominantly in triacylglycerols in the pheromone gland. Whether these stored acids are converted to pheromone later or not has been the subject of some debate. Using a tracer/tracee approach, in which we fed female Heliothis virescens U- 13 C-glucose, we were able to distinguish two pools of pheromone, in which precursors were temporally separated (after and before feeding on labeled glucose): DNP synthesized from a mixed tracer/tracee acetyl CoA pool after feeding, and pheromone made from precursor acids primarily synthesized before feeding, which we call recycled precursor fat pheromone (RPP). DNP titer varied from high (during scotophase) to low (photophase) and with presence/absence of pheromone biosynthesis activating neuropeptide (PBAN), in accord with native pheromone titer previously observed. By contrast, RPP was constant throughout the photoperiod and did not change with PBAN presence/absence. The amount of RPP (6.3-10.3 ng/female) was typically much lower than that of DNP, especially during the scotophase (peak DNP, 105 ng/female). We propose an integral role for stored fats in pheromone biosynthesis, in which they are hydrolyzed and re-esterified throughout the photoperiod, with a small proportion of liberated precursor acyl CoAs being converted to pheromone. During the sexually active period, release of PBAN results in increased flux of glucose (from trehalose) and hydrolyzed acids entering the mitochondria, producing acetyl CoA precursor for de novo fat and pheromone biosynthesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimal Cotton Insecticide Application Termination Timing: A Meta-Analysis.

PubMed

Griffin, T W; Zapata, S D

2016-08-01

The concept of insecticide termination timing is generally accepted among cotton (Gossypium hirsutum) researchers; however, exact timings are often disputed. Specifically, there is uncertainty regarding the last economic insecticide application to control fruit-feeding pests including tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)), boll weevil (Anthonomus grandis), bollworm (Helicoverpa zea), tobacco budworm (Heliothis virescens), and cotton fleahopper (Pseudatomoscelis seriatus). A systematic review of prior studies was conducted within a meta-analytic framework. Nine publicly available articles were amalgamated to develop an optimal timing principle. These prior studies reported 53 independent multiple means comparison field experiments for a total of 247 trial observations. Stochastic plateau theory integrated with econometric meta-analysis methodology was applied to the meta-database to determine the shape of the functional form of both the agronomic optimal insecticide termination timing and corresponding yield potential. Results indicated that current university insecticide termination timing recommendations are later than overall estimated timing suggested. The estimated 159 heat units (HU) after the fifth position above white flower (NAWF5) was found to be statistically different than the 194 HU termination used as the status quo recommended termination timing. Insecticides applied after 159 HU may have been applied in excess, resulting in unnecessary economic and environmental costs. Empirical results also suggested that extending the insecticide termination time by one unit resulted in a cotton lint yield increase of 0.27 kilograms per hectare up to the timing where the plateau began. Based on economic analyses, profit-maximizing producers may cease application as soon as 124 HU after NAWF5. These results provided insights useful to improve production systems by applying inputs only when benefits were expected to be in excess of the respective costs. © 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.

Interactions between the jasmonic and salicylic acid pathway modulate the plant metabolome and affect herbivores of different feeding types.

PubMed

Schweiger, R; Heise, A-M; Persicke, M; Müller, C

2014-07-01

The phytohormones jasmonic acid (JA) and salicylic acid (SA) mediate induced plant defences and the corresponding pathways interact in a complex manner as has been shown on the transcript and proteine level. Downstream, metabolic changes are important for plant-herbivore interactions. This study investigated metabolic changes in leaf tissue and phloem exudates of Plantago lanceolata after single and combined JA and SA applications as well as consequences on chewing-biting (Heliothis virescens) and piercing-sucking (Myzus persicae) herbivores. Targeted metabolite profiling and untargeted metabolic fingerprinting uncovered different categories of plant metabolites, which were influenced in a specific manner, indicating points of divergence, convergence, positive crosstalk and pronounced mutual antagonism between the signaling pathways. Phytohormone-specific decreases of primary metabolite pool sizes in the phloem exudates may indicate shifts in sink-source relations, resource allocation, nutrient uptake or photosynthesis. Survival of both herbivore species was significantly reduced by JA and SA treatments. However, the combined application of JA and SA attenuated the negative effects at least against H. virescens suggesting that mutual antagonism between the JA and SA pathway may be responsible. Pathway interactions provide a great regulatory potential for the plant that allows triggering of appropriate defences when attacked by different antagonist species. © 2013 John Wiley & Sons Ltd.

Pest-managing efficacy of trans-asarone isolated from Daucus carota L. seeds.

PubMed

Momin, Rafikali A; Nair, Muraleeddharan G

2002-07-31

The bioactive hexane extract of Daucus carota seed yielded 2,4,5-trimethoxybenzaldehyde (1), oleic acid (2), trans-asarone (3), and geraniol (4). Compounds 1-4 were evaluated for their mosquitocidal, nematicidal, antifeedant, and antimicrobial activities. Only trans-asarone was active in the assays performed, causing 100% mortality to fourth-instar mosquito larvae, Aedes aegyptii, at 200 microg mL(-1) and the nematodes Caenorhabditis elegans and Panagrellus redivivus at 100 microg mL(-1). In feeding trials, trans-asarone also caused significant weight reductions of the caterpillars Helicovarpa zea, Heliothis virescens, and Manduca sexta when incorporated into artificial diet at a concentration of 100 microg mL(-1). Also, it exhibited slight activity at 100 microg mL(-1) against the yeasts Candida albicans, Candida parapsilasis, and Candida kruseii.

Comparative Evaluation of Phenoloxidase Activity in Different Larval Stages of Four Lepidopteran Pests After Exposure to Bacillus thuringiensis

PubMed Central

Valadez-Lira, J.A.; Alcocer-Gonzalez, J.M.; Damas, G.; Nuñez-Mejía, G.; Oppert, B.; Rodriguez-Padilla, C.; Tamez-Guerra, P.

2012-01-01

Microbial entomopathogen—based bioinsecticides are recognized as alternatives to synthetic pesticides. Insects defend themselves against microbial pathogens by innate mechanisms, including increased phenoloxidase (PO) activity, but its relationship with microbial bioinsecticides efficacy is little known. This study evaluated the differences in PO activity at different developmental stages of the tobacco budworm Heliothis virescens Fabricius (Lepidoptera: Noctuidae), Indian meal moth Plodia interpunctella (Hübner) (Pyralidae), beet armyworm Spodoptera exigua (Hübner) (Noctuidae), and cabbage looper Trichoplusia ni (Hübner) (Noctuidae). Additionally, 2nd- and 4th-instars were exposed to the LC50 value of the commercial Bacillus thuringiensis (Bt) spray, Biobit®. The percentage of insecticidal activity (IA%) on 2nd-instar Biobit—exposed larvae was approximately the predicted 50 % mortality for all species except S. exigua. With all 4th instar Biobit—exposed larvae, mortality was not significantly different from that of unexposed larvae. Unexposed insects had a significantly higher PO activity in pre—pupae and pupae than early—instar larvae and adults, whereas PO activity was higher in adult females than in males. Correlation analysis between IA% and PO activity revealed significant r—values (p < 0.01) in 2nd instar H. virescens (r = 0.979) and P. interpunctella (r = 0.930). Second instar Biobit—exposed P. interpunctella had 10 times more PO activity than unexposed larvae. Similarly, the amount of total protein was lower in 4th instar Biobit—exposed H. virescens and higher in S. exigua. Therefore, the results indicated a relationship between Biobit susceptibility and PO activity in some cases. This information may be useful if the Biobit application period is timed for a developmental stage with low PO activity. However, more studies are needed to determine the correlation of each insect with a particular bioinsecticide. PMID:23414117

Comparative evaluation of phenoloxidase activity in different larval stages of four lepidopteran pests after exposure to Bacillus thuringiensis.

PubMed

Valadez-Lira, J A; Alcocer-Gonzalez, J M; Damas, G; Nuñez-Mejía, G; Oppert, B; Rodriguez-Padilla, C; Tamez-Guerra, P

2012-01-01

Microbial entomopathogen-based bioinsecticides are recognized as alternatives to synthetic pesticides. Insects defend themselves against microbial pathogens by innate mechanisms, including increased phenoloxidase (PO) activity, but its relationship with microbial bioinsecticides efficacy is little known. This study evaluated the differences in PO activity at different developmental stages of the tobacco budworm Heliothis virescens Fabricius (Lepidoptera: Noctuidae), Indian meal moth Plodia interpunctella (Hübner) (Pyralidae), beet armyworm Spodoptera exigua (Hübner) (Noctuidae), and cabbage looper Trichoplusia ni (Hübner) (Noctuidae). Additionally, 2(nd)- and 4(th)-instars were exposed to the LC(50) value of the commercial Bacillus thuringiensis (Bt) spray, Biobit(®). The percentage of insecticidal activity (IA%) on 2(nd)-instar Biobit-exposed larvae was approximately the predicted 50 % mortality for all species except S. exigua. With all 4(th) instar Biobit-exposed larvae, mortality was not significantly different from that of unexposed larvae. Unexposed insects had a significantly higher PO activity in pre-pupae and pupae than early-instar larvae and adults, whereas PO activity was higher in adult females than in males. Correlation analysis between IA% and PO activity revealed significant r-values (p < 0.01) in 2(nd) instar H. virescens (r = 0.979) and P. interpunctella (r = 0.930). Second instar Biobit-exposed P. interpunctella had 10 times more PO activity than unexposed larvae. Similarly, the amount of total protein was lower in 4(th) instar Biobit-exposed H. virescens and higher in S. exigua. Therefore, the results indicated a relationship between Biobit susceptibility and PO activity in some cases. This information may be useful if the Biobit application period is timed for a developmental stage with low PO activity. However, more studies are needed to determine the correlation of each insect with a particular bioinsecticide.

Molecular and functional characterization of cry1Ac transgenic pea lines.

PubMed

Teressa Negawo, Alemayehu; Baranek, Linda; Jacobsen, Hans-Jörg; Hassan, Fathi

2016-10-01

Transgenic pea lines transformed with the cry1Ac gene were characterized at molecular (PCR, RT-PCR, qRT-PCR and immunostrip assay) and functional levels (leaf paint and insect feeding bioassays). The results showed the presence, expression, inheritance and functionality of the introduced transgene at different progeny levels. Variation in the expression of the cry1Ac gene was observed among the different transgenic lines. In the insect bioassay studies using the larvae of Heliothis virescens, both larval survival and plant damage were highly affected on the different transgenic plants. Up to 100 % larval mortality was observed on the transgenic plants compared to 17.42 % on control plants. Most of the challenged transgenic plants showed very negligible to substantially reduced feeding damage indicating the insect resistance of the developed transgenic lines. Further analysis under field condition will be required to select promising lines for future uses.

Molecular and functional characterization of cry1Ac transgenic pea lines

PubMed Central

Teressa Negawo, Alemayehu; Baranek, Linda; Jacobsen, Hans-Jörg; Hassan, Fathi

2016-01-01

ABSTRACT Transgenic pea lines transformed with the cry1Ac gene were characterized at molecular (PCR, RT-PCR, qRT-PCR and immunostrip assay) and functional levels (leaf paint and insect feeding bioassays). The results showed the presence, expression, inheritance and functionality of the introduced transgene at different progeny levels. Variation in the expression of the cry1Ac gene was observed among the different transgenic lines. In the insect bioassay studies using the larvae of Heliothis virescens, both larval survival and plant damage were highly affected on the different transgenic plants. Up to 100 % larval mortality was observed on the transgenic plants compared to 17.42 % on control plants. Most of the challenged transgenic plants showed very negligible to substantially reduced feeding damage indicating the insect resistance of the developed transgenic lines. Further analysis under field condition will be required to select promising lines for future uses. PMID:27764552

Polymers for the stabilization and delivery of proteins topically and per os to the insect hemocoel through conjugation with aliphatic polyethylene glycol.

PubMed

Jeffers, Laura A; Shen, Hongyan; Bissinger, Brooke W; Khalil, Sayed; Gunnoe, T Brent; Roe, R Michael

2014-10-01

Co-feeding of aliphatic polyethylene glycol (PEG), phospholipase A2, anionic and ionic detergents, and amphipathic glycoside with bovine serum albumin (BSA) as a model protein to fourth stadium tobacco budworms, Heliothis virescens, did not affect the levels of BSA in the hemolymph. Covalent conjugation of small proteins like the decapeptide trypsin modulating oostatic factor (TMOF) to polyethylene glycol was previously shown to protect the peptide from protease attack and enhance its accumulation in the insect hemocoel. Whether this polymer chemistry could do the same for larger proteins was examined. The chemistry for the synthesis of polydispersed aliphatic PEG350-insulin and monodispersed aliphatic PEG333-insulin are described herein. Insulin was used for this synthesis and not BSA to better control conjugation among the available free amine groups. When PEGylated insulin or free insulin were fed in artificial diet to fifth stadium budworms, greater concentrations of insulin using the PEGylated variants were found in the hemolymph than when free insulin was used (a 6.7 and 7.3-fold increase for the PEG350 and PEG333 conjugates, respectively). When insulin is topically applied to the dorsum of H. virescens, no insulin is found in the hemolymph. However, after topical application of the PEGylated insulins, PEG350-insulin and PEG333-insulin were detected in the hemolymph. After injections of insulin into the hemocoel of fourth stadium H. virescens, insulin is completely cleared from the hemolymph in 120min. In comparison, PEG350-insulin and PEG333-insulin were present in the hemolymph for 300 and 240min after injection, respectively, translating to a 3.3 and 2.7-fold increase in the length of time insulin remains in the hemolymph after injection. Copyright © 2014 Elsevier Inc. All rights reserved.

in silico identification of cross affinity towards Cry1Ac pesticidal protein with receptor enzyme in Bos taurus and sequence, structure analysis of crystal proteins for stability.

PubMed

Ebenezer, King Solomon; Nachimuthu, Ramesh; Thiagarajan, Prabha; Velu, Rajesh Kannan

2013-01-01

Any novel protein introduced into the GM crops need to be evaluated for cross affinity on living organisms. Many researchers are currently focusing on the impact of Bacillus thuringiensis cotton on soil and microbial diversity by field experiments. In spite of this, in silico approach might be helpful to elucidate the impact of cry genes. The crystal a protein which was produced by Bt at the time of sporulation has been used as a biological pesticide to target the insectivorous pests like Cry1Ac for Helicoverpa armigera and Cry2Ab for Spodoptera sp. and Heliothis sp. Here, we present the comprehensive in silico analysis of Cry1Ac and Cry2Ab proteins with available in silico tools, databases and docking servers. Molecular docking of Cry1Ac with procarboxypeptidase from Helicoverpa armigera and Cry1Ac with Leucine aminopeptidase from Bos taurus has showed the 125(th) amino acid position to be the preference site of Cry1Ac protein. The structures were compared with each other and it showed 5% of similarity. The cross affinity of this toxin that have confirmed the earlier reports of ill effects of Bt cotton consumed by cattle.

Biochemical crypsis in the avoidance of natural enemies by an insect herbivore

PubMed Central

De Moraes, Consuelo M.; Mescher, Mark C.

2004-01-01

Plant-herbivore interactions provide well studied examples of coevolution, but little is known about how such interactions are influenced by the third trophic level. Here we show that larvae of the specialized lepidopteran herbivore Heliothis subflexa reduce their vulnerability to natural enemies through adaptation to a remarkable and previously unknown feature of their host plant, Physalis angulata: The fruits of this plant lack linolenic acid (LA), which is required for the development of most insects. By overcoming this nutritional deficiency, H. subflexa larvae achieve numerous advantages. First, they gain near-exclusive access to a food resource: we demonstrate that closely related Heliothis virescens larvae cannot develop on P. angulata fruit unless the fruit are treated with LA. Second, they reduce their vulnerability to enemies: LA is a key component of volicitin, an elicitor of plant-volatile-signaling defenses. We demonstrate that volicitin is absent in the oral secretions of fruit-feeding caterpillars, that the volatile profiles of plants induced by fruit feeding differ from those induced by leaf feeding or by feeding on LA-treated fruit, and that the former are far less attractive to female Cardiochiles nigriceps parasitoids. Finally, they render themselves nutritionally unsuitable as hosts for enemies that require LA for their own development: we show that C. nigriceps larvae fail to develop within the bodies of fruit-feeding caterpillars but do develop in caterpillars feeding on LA-treated fruit. Thus, H. subflexa larvae not only overcome a serious dietary deficiency but also reduce their vulnerability to natural enemies through a form of “biochemical crypsis.” PMID:15184664

Biochemical crypsis in the avoidance of natural enemies by an insect herbivore.

PubMed

De Moraes, Consuelo M; Mescher, Mark C

2004-06-15

Plant-herbivore interactions provide well studied examples of coevolution, but little is known about how such interactions are influenced by the third trophic level. Here we show that larvae of the specialized lepidopteran herbivore Heliothis subflexa reduce their vulnerability to natural enemies through adaptation to a remarkable and previously unknown feature of their host plant, Physalis angulata: The fruits of this plant lack linolenic acid (LA), which is required for the development of most insects. By overcoming this nutritional deficiency, H. subflexa larvae achieve numerous advantages. First, they gain near-exclusive access to a food resource: we demonstrate that closely related Heliothis virescens larvae cannot develop on P. angulata fruit unless the fruit are treated with LA. Second, they reduce their vulnerability to enemies: LA is a key component of volicitin, an elicitor of plant-volatile-signaling defenses. We demonstrate that volicitin is absent in the oral secretions of fruit-feeding caterpillars, that the volatile profiles of plants induced by fruit feeding differ from those induced by leaf feeding or by feeding on LA-treated fruit, and that the former are far less attractive to female Cardiochiles nigriceps parasitoids. Finally, they render themselves nutritionally unsuitable as hosts for enemies that require LA for their own development: we show that C. nigriceps larvae fail to develop within the bodies of fruit-feeding caterpillars but do develop in caterpillars feeding on LA-treated fruit. Thus, H. subflexa larvae not only overcome a serious dietary deficiency but also reduce their vulnerability to natural enemies through a form of "biochemical crypsis."

Disposable Polydimethylsiloxane (PDMS)-Coated Fused Silica Optical Fibers for Sampling Pheromones of Moths.

PubMed

Lievers, Rik; Groot, Astrid T

2016-01-01

In the past decades, the sex pheromone composition in female moths has been analyzed by different methods, ranging from volatile collections to gland extractions, which all have some disadvantage: volatile collections can generally only be conducted on (small) groups of females to detect the minor pheromone compounds, whereas gland extractions are destructive. Direct-contact SPME overcomes some of these disadvantages, but is expensive, the SPME fiber coating can be damaged due to repeated usage, and samples need to be analyzed relatively quickly after sampling. In this study, we assessed the suitability of cheap and disposable fused silica optical fibers coated with 100 μm polydimethylsiloxane (PDMS) by sampling the pheromone of two noctuid moths, Heliothis virescens and Heliothis subflexa. By rubbing the disposable PDMS fibers over the pheromone glands of females that had called for at least 15 minutes and subsequently extracting the PDMS fibers in hexane, we collected all known pheromone compounds, and we found a strong positive correlation for most pheromone compounds between the disposable PDMS fiber rubs and the corresponding gland extracts of the same females. When comparing this method to volatile collections and the corresponding gland extracts, we generally found comparable percentages between the three techniques, with some differences that likely stem from the chemical properties of the individual pheromone compounds. Hexane extraction of cheap, disposable, PDMS coated fused silica optical fibers allows for sampling large quantities of individual females in a short time, eliminates the need for immediate sample analysis, and enables to use the same sample for multiple chemical analyses.

Disposable Polydimethylsiloxane (PDMS)-Coated Fused Silica Optical Fibers for Sampling Pheromones of Moths

PubMed Central

Lievers, Rik; Groot, Astrid T.

2016-01-01

In the past decades, the sex pheromone composition in female moths has been analyzed by different methods, ranging from volatile collections to gland extractions, which all have some disadvantage: volatile collections can generally only be conducted on (small) groups of females to detect the minor pheromone compounds, whereas gland extractions are destructive. Direct-contact SPME overcomes some of these disadvantages, but is expensive, the SPME fiber coating can be damaged due to repeated usage, and samples need to be analyzed relatively quickly after sampling. In this study, we assessed the suitability of cheap and disposable fused silica optical fibers coated with 100 μm polydimethylsiloxane (PDMS) by sampling the pheromone of two noctuid moths, Heliothis virescens and Heliothis subflexa. By rubbing the disposable PDMS fibers over the pheromone glands of females that had called for at least 15 minutes and subsequently extracting the PDMS fibers in hexane, we collected all known pheromone compounds, and we found a strong positive correlation for most pheromone compounds between the disposable PDMS fiber rubs and the corresponding gland extracts of the same females. When comparing this method to volatile collections and the corresponding gland extracts, we generally found comparable percentages between the three techniques, with some differences that likely stem from the chemical properties of the individual pheromone compounds. Hexane extraction of cheap, disposable, PDMS coated fused silica optical fibers allows for sampling large quantities of individual females in a short time, eliminates the need for immediate sample analysis, and enables to use the same sample for multiple chemical analyses. PMID:27533064

Immune modulation enables a specialist insect to benefit from antibacterial withanolides in its host plant

PubMed Central

Barthel, Andrea; Vogel, Heiko; Pauchet, Yannick; Pauls, Gerhard; Kunert, Grit; Groot, Astrid T.; Boland, Wilhelm; Heckel, David G.; Heidel-Fischer, Hanna M.

2016-01-01

The development of novel plant chemical defenses and counter adaptations by herbivorous insect could continually drive speciation, producing more insect specialists than generalists. One approach to test this hypothesis is to compare closely related generalist and specialist species to reveal the associated costs and benefits of these different adaptive strategies. We use the specialized moth Heliothis subflexa, which feeds exclusively on plants in the genus Physalis, and its close generalist relative H. virescens. Specialization on Physalis plants necessitates the ability to tolerate withanolides, the secondary metabolites of Physalis species that are known to have feeding deterrent and immune inhibiting properties for other insects. Here we find that only H. subflexa benefits from the antibacterial properties of withanolides, and thereby gains a higher tolerance of the pathogen Bacillus thuringiensis. We argue that the specialization in H. subflexa has been guided to a large extent by a unique role of plant chemistry on ecological immunology. PMID:27561781

Effects of copper and tributyltin on stress protein abundance in the rotifer Brachionus plicatilis.

PubMed

Cochrane, B J; Irby, R B; Snell, T W

1991-01-01

1. Exposure of the rotifer Brachionus plicatilis to elevated temperature resulted in the synthesis of a number of proteins, including a prominent one of 58,000 Da (SP58). 2. This protein is immunologically crossreactive with the 65,000 Da heat shock protein of the moth Heliothis virescens, which is a member of a highly conserved family of mitochondrial proteins. 3. Exposure of rotifers to sublethal doses of CuSO4 leads to a 4-5-fold increase in abundance of SP58, with maximum increase occurring at a dose that is approximately 5% of the LC50 for that compound. 4. A similar response was seen with tributyl tin (TBT). Kinetics of induction were sigmoidal, with induction occurring in the range of 20-30 micrograms/l. 5. No response was observed when rotifers were exposed to aluminum chloride, mercury chloride, pentachlorophenol, sodium arsenite, sodium azide, sodium dodecyl sulfate, or zinc chloride. 6. These results indicate that changes in stress protein abundance may prove useful as a biomarker of exposure to particular toxicants.

Toxicities of emamectin benzoate homologues and photodegradates to Lepidoptera.

PubMed

Argentine, Joseph A; Jansson, Richard K; Starner, Van R; Halliday, W Ross

2002-12-01

The toxicity of a number of emamectin benzoate homologues and photodegradates to five species of Lepidoptera was investigated using diet and foliar bioassays. The emamectin benzoate homologues B1a and B1b were equally toxic in the diet and foliar assays to Spodoptera exigua (Hübner), Heliothis virescens (F.), Tricoplusia ni (Hübner), and Spodoptera frugiperda (J. E. Smith), within each of these species. Plutella xylostella (L.) was the most sensitive species to emamectin benzoate. The AB1a photodegradate of emamectin benzoate was as toxic as the parent compound in the diet assay. However, in the foliage assay AB1a was 4.4-fold less toxic to S. exigua than the parent compound. The MFB1a photodegradate of emamectin benzoate was as toxic as the parent compound to P. xylostella, and 3.1 to 6.2 times as toxic as the parent compound to the other species in the diet assay. The order of toxicity of the photodegradates were AB1a > MFB1a > FAB1a > 8,9-Z-MAB1a > PAB1a.

Amtyr1: characterization of a gene from honeybee (Apis mellifera) brain encoding a functional tyramine receptor.

PubMed

Blenau, W; Balfanz, S; Baumann, A

2000-03-01

Biogenic amine receptors are involved in the regulation and modulation of various physiological and behavioral processes in both vertebrates and invertebrates. We have cloned a member of this gene family from the CNS of the honeybee, Apis mellifera. The deduced amino acid sequence is homologous to tyramine receptors cloned from Locusta migratoria and Drosophila melanogaster as well as to an octopamine receptor cloned from Heliothis virescens. Functional properties of the honeybee receptor were studied in stably transfected human embryonic kidney 293 cells. Tyramine reduced forskolin-induced cyclic AMP production in a dose-dependent manner with an EC50 of approximately 130 nM. A similar effect of tyramine was observed in membrane homogenates of honeybee brains. Octopamine also reduced cyclic AMP production in the transfected cell line but was both less potent (EC50 of approximately 3 microM) and less efficacious than tyramine. Receptor-encoding mRNA has a wide-spread distribution in the brain and subesophageal ganglion of the honeybee, suggesting that this tyramine receptor is involved in sensory signal processing as well as in higher-order brain functions.

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

Ding, Y.S.

(9, 10-/sup 3/H/sub 2/)Z9-14:Ac was synthesized at high specific activity (/sup 3/H, 58 Ci/mmole) by partial tritiation of the corresponding alkyne and was converted to the labeled Z9-14:OH and Z9-14:Al to study tissue specificity of acetate esterase (E), alcohol oxidase (OX), and aldehyde dehydrogenase (ALDH) in male and female Heliothis virescens. Soluble and membrane-associated enzyme activities were determined by radio-TLC assays. Compounds of the tritium-labeled Z11-16 series were synthesized and their in vitro fates examined as well. In order to achieve an alternative approach in which (1) pheromone receptor proteins would be stoichiometrically and irreversibly modified, or (2) pheromone-catabolizing enzymesmore » are inactivated by tight-binding or irreversible inhibitors, we have designed analogues of pheromones of lepidopterous insect pests and assayed their biological activity in vitro and in vivo. Various fluorinated molecules such as acyl fluorides, fluoroolefins, 2-fluoro aldehydes, 2,2-difluoro aldehydes and trifluoromethyl ketones were synthesized. The synthesis of some other functional groups such as cyclopropanones, cyclopropanols, cyclopropyl carbinols, cyclopropyl aldehydes and Michael acceptors will also be discussed.« less

Construction and sequence sampling of deep-coverage, large-insert BAC libraries for three model lepidopteran species

PubMed Central

Wu, Chengcang; Proestou, Dina; Carter, Dorothy; Nicholson, Erica; Santos, Filippe; Zhao, Shaying; Zhang, Hong-Bin; Goldsmith, Marian R

2009-01-01

Background Manduca sexta, Heliothis virescens, and Heliconius erato represent three widely-used insect model species for genomic and fundamental studies in Lepidoptera. Large-insert BAC libraries of these insects are critical resources for many molecular studies, including physical mapping and genome sequencing, but not available to date. Results We report the construction and characterization of six large-insert BAC libraries for the three species and sampling sequence analysis of the genomes. The six BAC libraries were constructed with two restriction enzymes, two libraries for each species, and each has an average clone insert size ranging from 152–175 kb. We estimated that the genome coverage of each library ranged from 6–9 ×, with the two combined libraries of each species being equivalent to 13.0–16.3 × haploid genomes. The genome coverage, quality and utility of the libraries were further confirmed by library screening using 6~8 putative single-copy probes. To provide a first glimpse into these genomes, we sequenced and analyzed the BAC ends of ~200 clones randomly selected from the libraries of each species. The data revealed that the genomes are AT-rich, contain relatively small fractions of repeat elements with a majority belonging to the category of low complexity repeats, and are more abundant in retro-elements than DNA transposons. Among the species, the H. erato genome is somewhat more abundant in repeat elements and simple repeats than those of M. sexta and H. virescens. The BLAST analysis of the BAC end sequences suggested that the evolution of the three genomes is widely varied, with the genome of H. virescens being the most conserved as a typical lepidopteran, whereas both genomes of H. erato and M. sexta appear to have evolved significantly, resulting in a higher level of species- or evolutionary lineage-specific sequences. Conclusion The high-quality and large-insert BAC libraries of the insects, together with the identified BACs containing genes of interest, provide valuable information, resources and tools for comprehensive understanding and studies of the insect genomes and for addressing many fundamental questions in Lepidoptera. The sample of the genomic sequences provides the first insight into the constitution and evolution of the insect genomes. PMID:19558662

Molecular cloning of the pheromone biosynthesis-activating neuropeptide in Helicoverpa zea.

PubMed Central

Davis, M T; Vakharia, V N; Henry, J; Kempe, T G; Raina, A K

1992-01-01

Pheromone biosynthesis-activating neuropeptide (PBAN) regulates sex pheromone biosynthesis in female Helicoverpa (Heliothis) zea. Two oligonucleotide probes representing two overlapping amino acid regions of PBAN were used to screen 2.5 x 10(5) recombinant plaques, and a positive recombinant clone was isolated. Sequence analysis of the isolated clone showed that the PBAN gene is interrupted after the codon encoding amino acid 14 by a 0.63-kilobase (kb) intron. Preceding the PBAN amino acid sequence is a 10-amino acid sequence containing a pentapeptide Phe-Thr-Pro-Arg-Leu, which is followed by a Gly-Arg-Arg processing site. Immediately after the PBAN amino acid sequence is a Gly-Arg processing site and a short stretch of 10 amino acids. This 10-amino acid sequence contains a repeat of the PBAN C-terminal pentapeptide Phe-Ser-Pro-Arg-Leu and is terminated by another Gly-Arg processing site. It is suggested that the PBAN gene in H. zea might carry, besides PBAN, a 7- and an 8-residue amidated peptide, which share with PBAN the core C-terminal pentapeptide Phe-(Ser or Thr)-Pro-Arg-Leu-NH2. The C-terminal pentapeptide sequence of PBAN represents the minimum sequence required for pheromonotropic activity in H. zea and also bears a high degree of homology to the pyrokinin family of insect peptides with myotropic activity. It is possible that the putative heptapeptide and octapeptide might be new members of the pyrokinin family, with pheromonotropic and/or myotropic activities. Thus, the PBAN gene products, besides affecting sexual behavior, might have broad influence on many biological processes in H. zea. Images PMID:1729680

Egg production and oviposition in the tobacco budworm: effect of age at mating

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

Proshold, F.I.; Karpenko, C.P.; Graham, C.K.

1982-01-01

Female tobacco budworms, Heliothis virescens (F.) (Lepidoptera: Noctuidae), that emerged in the laboratory contained no mature eggs, although ooecyte development had proceeded as far as yolk deposition in the ultimate egg of each ovariole. After 18 h, ca. one mature egg per ovariole was present. If the females subsequently remained unmated, maturation of additional eggs was curvilinear with age and leveled off at ca. 500 eggs per female at 120 h. If the females mated, there was an inverse relationship between egg production and age mated; maximal production occurred when females mated the first night postemergence (ca. 30 h), andmore » production then diminished until females mating at 5 days or more laid only slightly more eggs than virgin females. However, there was also a direct relationship between length of life and age of mating. Females that mated at 1 or 2 days showed a signficant correlation between numbers of eggs produced and longevity and between numbers of eggs and pupal weight. Virgin females and females that mated at 3 days showed a significant correlation between eggs and longevity but not between eggs and pupal weight. There was no significant correlation between eggs and pupal weight or longevity for females that mated at 5 days or later.« less

A specific affinity reagent to distinguish aldehyde dehydrogenases and oxidases. Enzymes catalyzing aldehyde oxidation in an adult moth

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

Tasayco, M.L.; Prestwich, G.D.

1990-02-25

Aldehyde dehydrogenase (ALDH) and oxidase (AO) enzymes from the tissue extracts of male and female tobacco budworm moth (Heliothis virescens) were identified after electrophoretic protein separation. AO activity was visualized using formazan- or horseradish peroxidase-mediated staining coupled to the AO-catalyzed oxidation of benzaldehyde. A set of six soluble AO enzymes with isoelectric points from pI 4.6 to 5.3 were detected primarily in the antennal extracts. Partially purified antennal AO enzymes also oxidized both (Z)-9-tetradecenal and (Z)-11-hexadecenal, the two major pheromone components of this moth. ALDH activity was detected using a tritium-labeled affinity reagent based on a known irreversible inhibitor ofmore » this enzyme. This labeled vinyl ketone, (3H)(Z)-1,11-hexadecadien-3-one, was synthesized and used to covalently modify the soluble ALDH enzymes from tissue extracts. Molecular subunits of potential ALDH enzymes were visualized in the fluorescence autoradiograms of sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated proteins of the antenna, head, and leg tissues. Covalent modification of these protein subunits decreased specifically in the presence of excess pheromone aldehyde or benzaldehyde. Labeled vinyl ketones are thus novel tools for the identification of molecular subunits of ALDH enzymes.« less

Cloning and sequence analysis of Galleria mellonella juvenile hormone binding protein--a search for ancestors and relatives.

PubMed

Rodriguez Parkitna, Jan M; Ozyhar, Andrzej; Wiśniewski, Jacek R; Kochman, Marian

2002-09-01

Juvenile hormone binding proteins (JHBPs) serve as specific carriers of juvenile hormone (JH) in insect hemolymph. As shown in this report, Galleria mellonella JHBP is encoded by a cDNA of 1063 nucleotides. The pre-protein consists of 245 amino acids with a 20 amino acid leader sequence. The concentration of the JHBP mRNA reaches a maximum on the third day of the last larval instar, and decreases five-fold towards pupation. Comparison of amino acid sequences of JHBPs from Bombyx mori, Heliothis virescens, Manduca sexta and G. mellonella shows that 57 positions out of 226 are occupied by identical amino acids. A phylogeny tree was constructed from 32 proteins, which function could be associated to JH. It has three major branches: (i) ligand binding domains of nuclear receptors, (ii) JHBPs and JH esterases (JHEs), and (iii) hypothetical proteins found in Drosophila melanogaster genome. Despite the close positioning of JHEs and JHBPs on the tree, which probably arises from the presence of a common JH binding motif, these proteins are unlikely to belong to the same family. Detailed analysis of the secondary structure modeling shows that JHBPs may contain a beta-barrel motif flanked by alpha-helices and thus be evolutionary related to the same superfamily as calycins.

Characterization of Nonjunctional Hemichannels in Caterpillar Cells

PubMed Central

Luo, Kaijun; Turnbull, Matthew W.

2011-01-01

Recent studies have demonstrated that hemichannels, which form gap junctions when paired from apposing cells, may serve additional roles when unpaired including cell adhesion and paracrine communication. Hemichannels in mammals are formed by connexins or pannexins, while in insects they are formed by pannexin homologues termed innexins. The formation of functional gap junctions by insect innexins has been established, although their ability to form functional nonjunctional hemichannels has not been reported. Here the characteristics of nonjunctional hemichannels were examined in three lepidopteran cell types, two cell lines (High Five and Sf9) and explanted hemocytes from Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae). Selective fluorescent dye uptake by hemichannels was observed in a significant minority of cells, using fluorescence microscopy and flow cytometry. Carbenoxelone, an inhibitor of mammalian junctions, disrupted dye uptake, while flufenamic acid and mefloquine did not. The presence of Ca2+ and Mg2+ in the media increased hemichannel activity. Additionally, lipopolysaccharide, a stimulator of immune activity in lepidopterans, decreased dye uptake. These results demonstrate for the first time the activity of nonjunctional hemichannels in insect cells, as well as pharmacological tools to manipulate them. These results will facilitate the further examination of the role of innexins and nonjunctional hemichannels in insect cell biology, including paracrine signaling, and comparative studies of mammalian pannexins and insect innexins. PMID:21521140

An ascovirus isolated from Spodoptera litura (Noctuidae: Lepidoptera) transmitted by the generalist endoparasitoid Meteorus pulchricornis (Braconidae: Hymenoptera).

PubMed

Arai, Eiko; Ishii, Kazuo; Ishii, Hiroki; Sagawa, Shiori; Makiyama, Nao; Mizutani, Tetsuya; Omatsu, Tsutomu; Katayama, Yukie; Kunimi, Yasuhisa; Inoue, Maki N; Nakai, Madoka

2018-04-01

The family Ascoviridae is a recently described virus family whose members are transmitted by parasitoids and cause chronic and lethal infections in lepidopteran insects. Little is known about the biology and ecology of ascoviruses, and few isolates have been found outside the United States. We report here the isolation of a new ascovirus variant from Spodoptera litura in Japan. Full genome sequence and phylogenetic analyses showed that this virus was closely related to variants in Heliothis virescens ascovirus-3a, and it was named HvAV-3j. HvAV-3j has a DNA genome of 191 718 bp, with 189 putative ORFs and a GC content of 45.6 %, and is highly similar to HvAV-3h, which was isolated in China. In a field survey, the endoparasitoid Meteorus pulchricornis caused a high percentage of parasitization in populations of S. litura larvae, and under laboratory conditions M. pulchricornis was able to transmit HvAV-3j from infected to uninfected larvae by oviposition. Meteorus pulchricornis is thus likely to be a major vector for HvAV-3j transmission in Japan. This species is recognized here for the first time as a vector of ascoviruses that parasitizes a range of host species that extends across families.

The Dynamics of Pheromone Gland Synthesis and Release: a Paradigm Shift for Understanding Sex Pheromone Quantity in Female Moths.

PubMed

Foster, Stephen P; Anderson, Karin G; Casas, Jérôme

2018-05-10

Moths are exemplars of chemical communication, especially with regard to specificity and the minute amounts they use. Yet, little is known about how females manage synthesis and storage of pheromone to maintain release rates attractive to conspecific males and why such small amounts are used. We developed, for the first time, a quantitative model, based on an extensive empirical data set, describing the dynamical relationship among synthesis, storage (titer) and release of pheromone over time in a moth (Heliothis virescens). The model is compartmental, with one major state variable (titer), one time-varying (synthesis), and two constant (catabolism and release) rates. The model was a good fit, suggesting it accounted for the major processes. Overall, we found the relatively small amounts of pheromone stored and released were largely a function of high catabolism rather than a low rate of synthesis. A paradigm shift may be necessary to understand the low amounts released by female moths, away from the small quantities synthesized to the (relatively) large amounts catabolized. Future research on pheromone quantity should focus on structural and physicochemical processes that limit storage and release rate quantities. To our knowledge, this is the first time that pheromone gland function has been modeled for any animal.

Sex-specific consequences of an induced immune response on reproduction in a moth.

PubMed

Barthel, Andrea; Staudacher, Heike; Schmaltz, Antje; Heckel, David G; Groot, Astrid T

2015-12-16

Immune response induction benefits insects in combatting infection by pathogens. However, organisms have a limited amount of resources available and face the dilemma of partitioning resources between immunity and other life-history traits. Since males and females differ in their life histories, sex-specific resource investment strategies to achieve an optimal immune response following an infection can be expected. We investigated immune response induction of females and males of Heliothis virescens in response to the entomopathogenic bacterium Serratia entomophila, and its effects on mating success and the female sexual signal. We found that females had higher expression levels of immune-related genes after bacterial challenge than males. However, males maintained a higher baseline expression of immune-related genes than females. The increased investment in immunity of female moths was negatively correlated with mating success and the female sexual signal. Male mating success was unaffected by bacterial challenge. Our results show that the sexes differed in their investment strategies: females invested in immune defense after a bacterial challenge, indicating facultative immune deployment, whereas males had higher baseline immunity than females, indicating immune maintenance. Interestingly, these differences in investment were reflected in the mate choice assays. As female moths are the sexual signallers, females need to invest resources in their attractiveness. However, female moths appeared to invest in immunity at the cost of reproductive effort.

Influence of cover crops on insect pests and predators in conservation tillage cotton.

PubMed

Tillman, Glynn; Schomberg, Harry; Phatak, Sharad; Mullinix, Benjamin; Lachnicht, Sharon; Timper, Patricia; Olson, Dawn

2004-08-01

In fall 2000, an on-farm sustainable agricultural research project was established for cotton, Gossypium hirsutum L., in Tift County, Georgia. The objective of our 2-yr research project was to determine the impact of several cover crops on pest and predator insects in cotton. The five cover crop treatments included 1) cereal rye, Secale cereale L., a standard grass cover crop; 2) crimson clover, Trifolium incarnatum L., a standard legume cover crop; 3) a legume mixture of balansa clover, Trifolium michelianum Savi; crimson clover; and hairy vetch, Vicia villosa Roth; 4) a legume mixture + rye combination; and 5) no cover crop in conventionally tilled fields. Three main groups or species of pests were collected in cover crops and cotton: 1) the heliothines Heliothis virescens (F.) and Helicoverpa zea (Boddie); 2) the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois); and 3) stink bugs. The main stink bugs collected were the southern green stink bug, Nezara viridula (L.); the brown stink bug, Euschistus servus (Say); and the green stink bug, Acrosternum hilare (Say). Cotton aphids, Aphis gossypii Glover, were collected only on cotton. For both years of the study, the heliothines were the only pests that exceeded their economic threshold in cotton, and the number of times this threshold was exceeded in cotton was higher in control cotton than in crimson clover and rye cotton. Heliothine predators and aphidophagous lady beetles occurred in cover crops and cotton during both years of the experiment. Geocoris punctipes (Say), Orius insidiosus (Say), and red imported fire ant, Solenopsis invicta Buren were relatively the most abundant heliothine predators observed. Lady beetles included the convergent lady beetle, Hippodamia convergens Guérin-Méneville; the sevenspotted lady beetle, Coccinella septempunctata L.; spotted lady beetle, Coleomegilla maculata (DeGeer); and the multicolored Asian lady beetle, Harmonia axyridis (Pallas). Density of G. punctipes was higher in cotton fields previously planted in crimson clover compared with control cotton fields for all combined sampling dates in 2001. Intercropping cotton in live strips of cover crop was probably responsible for the relay of G. punctipes onto cotton in these crimson clover fields. Density of O. insidiosus was not significantly different between cover crop and control cotton fields. Lady beetles seemed to relay from cover crops into cotton. Conservation of the habitat of fire ants during planting probably was responsible for the higher density of red imported fire ants observed in all conservation tillage cotton fields relative to control cotton fields. Reduction in the number of times in which economic thresholds for heliothines were exceeded in crimson clover and rye compared with control fields indicated that the buildup of predaceous fire ants and G. punctipes in these cover crops subsequently resulted in reduction in the level of heliothines in conservation tillage cotton with these cover crops compared with conventional tillage cotton without cover crops.

Cotton Defense Induction Patterns Under Spatially, Temporally and Quantitatively Varying Herbivory Levels.

PubMed

Eisenring, Michael; Meissle, Michael; Hagenbucher, Steffen; Naranjo, Steven E; Wettstein, Felix; Romeis, Jörg

2017-01-01

In its defense against herbivores, cotton ( Gossypium sp.) relies in part on the production of a set of inducible, non-volatile terpenoids. Under uniform damage levels, in planta allocation of induced cotton terpenoids has been found to be highest in youngest leaves, supporting assumptions of the optimal defense theory (ODT) which predicts that plants allocate defense compounds to tissues depending on their value and the likelihood of herbivore attack. However, our knowledge is limited on how varying, and thus more realistic, damage levels might affect cotton defense organization. We hypothesized that the allocation of terpenoids and densities of terpenoid-storing glands in leaves aligns with assumptions of the ODT, even when plants are subjected to temporally, spatially and quantitatively varying caterpillar ( Heliothis virescens ) damage. As expected, cotton plants allocated most of their defenses to their youngest leaves regardless of damage location. However, defense induction in older leaves varied with damage location. For at least 14 days after damage treatments ended, plants reallocated defense resources from previously young leaves to newly developed leaves. Furthermore, we observed a positive hyperbolic relationship between leaf damage area and both terpenoid concentrations and gland densities, indicating that cotton plants can fine-tune defense allocation. Although it appears that factors like vascular constraints and chemical properties of individual defense compounds can affect defense levels, our results overall demonstrate that induced defense organization of cotton subjected to varying damage treatments is in alignment with key assumptions of the ODT.

Cotton Defense Induction Patterns Under Spatially, Temporally and Quantitatively Varying Herbivory Levels

PubMed Central

Eisenring, Michael; Meissle, Michael; Hagenbucher, Steffen; Naranjo, Steven E.; Wettstein, Felix; Romeis, Jörg

2017-01-01

In its defense against herbivores, cotton (Gossypium sp.) relies in part on the production of a set of inducible, non-volatile terpenoids. Under uniform damage levels, in planta allocation of induced cotton terpenoids has been found to be highest in youngest leaves, supporting assumptions of the optimal defense theory (ODT) which predicts that plants allocate defense compounds to tissues depending on their value and the likelihood of herbivore attack. However, our knowledge is limited on how varying, and thus more realistic, damage levels might affect cotton defense organization. We hypothesized that the allocation of terpenoids and densities of terpenoid-storing glands in leaves aligns with assumptions of the ODT, even when plants are subjected to temporally, spatially and quantitatively varying caterpillar (Heliothis virescens) damage. As expected, cotton plants allocated most of their defenses to their youngest leaves regardless of damage location. However, defense induction in older leaves varied with damage location. For at least 14 days after damage treatments ended, plants reallocated defense resources from previously young leaves to newly developed leaves. Furthermore, we observed a positive hyperbolic relationship between leaf damage area and both terpenoid concentrations and gland densities, indicating that cotton plants can fine-tune defense allocation. Although it appears that factors like vascular constraints and chemical properties of individual defense compounds can affect defense levels, our results overall demonstrate that induced defense organization of cotton subjected to varying damage treatments is in alignment with key assumptions of the ODT. PMID:28270830

The nicotinic acetylcholine receptor gene family of the honey bee, Apis mellifera

PubMed Central

Jones, Andrew K.; Raymond-Delpech, Valerie; Thany, Steeve H.; Gauthier, Monique; Sattelle, David B.

2006-01-01

Nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission and play roles in many cognitive processes. They are under intense research as potential targets of drugs used to treat neurodegenerative diseases and neurological disorders such as Alzheimer's disease and schizophrenia. Invertebrate nAChRs are targets of anthelmintics as well as a major group of insecticides, the neonicotinoids. The honey bee, Apis mellifera, is one of the most beneficial insects worldwide, playing an important role in crop pollination, and is also a valuable model system for studies on social interaction, sensory processing, learning, and memory. We have used the A. mellifera genome information to characterize the complete honey bee nAChR gene family. Comparison with the fruit fly Drosophila melanogaster and the malaria mosquito Anopheles gambiae shows that the honey bee possesses the largest family of insect nAChR subunits to date (11 members). As with Drosophila and Anopheles, alternative splicing of conserved exons increases receptor diversity. Also, we show that in one honey bee nAChR subunit, six adenosine residues are targeted for RNA A-to-I editing, two of which are evolutionarily conserved in Drosophila melanogaster and Heliothis virescens orthologs, and that the extent of editing increases as the honey bee lifecycle progresses, serving to maximize receptor diversity at the adult stage. These findings on Apis mellifera enhance our understanding of nAChR functional genomics and provide a useful basis for the development of improved insecticides that spare a major beneficial insect species. PMID:17065616

Identification of receptors of main sex-pheromone components of three Lepidopteran species.

PubMed

Mitsuno, Hidefumi; Sakurai, Takeshi; Murai, Masatoshi; Yasuda, Tetsuya; Kugimiya, Soichi; Ozawa, Rika; Toyohara, Haruhiko; Takabayashi, Junji; Miyoshi, Hideto; Nishioka, Takaaki

2008-09-01

Male moths discriminate conspecific female-emitted sex pheromones. Although the chemical components of sex pheromones have been identified in more than 500 moth species, only three components in Bombyx mori and Heliothis virescens have had their receptors identified. Here we report the identification of receptors for the main sex-pheromone components in three moth species, Plutella xylostella, Mythimna separata and Diaphania indica. We cloned putative sex-pheromone receptor genes PxOR1, MsOR1 and DiOR1 from P. xylostella, M. separata and D. indica, respectively. Each of the three genes was exclusively expressed with an Or83b orthologous gene in male olfactory receptor neurons (ORNs) that are surrounded by supporting cells expressing pheromone-binding-protein (PBP) genes. By two-electrode voltage-clamp recording, we tested the ligand specificity of Xenopus oocytes co-expressing PxOR1, MsOR1 or DiOR1 with an OR83b family protein. Among the seven sex-pheromone components of the three moth species, the oocytes dose-dependently responded only to the main sex-pheromone component of the corresponding moth species. In our study, PBPs were not essential for ligand specificity of the receptors. On the phylogenetic tree of insect olfactory receptors, the six sex-pheromone receptors identified in the present and previous studies are grouped in the same subfamily but have no relation with the taxonomy of moths. It is most likely that sex-pheromone receptors have randomly evolved from ancestral sex-pheromone receptors before the speciation of moths and that their ligand specificity was modified by mutations of local amino acid sequences after speciation.

Influence of Host Gender on Infection Rate, Density and Distribution of the Parasitic Fungus, Hesperomyces virescens, on the Multicolored Asian Lady Beetle, Harmonia axyridis

PubMed Central

Riddick, E. W.

2006-01-01

Hesperomyces virescens Thaxter (Laboulbeniales: Laboulbeniaceae) is a parasitic fungus that infects lady beetles (Coleoptera: Coccinellidae) via horizontal transmission between adults at overwintering and feeding sites. The differential behavior of male and female hosts could have profound effects on intensity of infection and positioning of fungus on the host's integument. The influence of host gender on infection rate, density and distribution of this parasite on the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), was determined at a feeding site. Adult H. axyridis were sampled from pecan, Carya illinoinensis (Wangenh.) K. Koch, trees in northern Mississippi, USA, during summer and early fall 2003–2004. Results indicated that the behavior of male or female beetles on pecan trees had only a limited effect on the intensity of infection. When averaged over the entire season, the percentage of H. axyridis infected with H. virescens was not influenced by host gender. In 2003, a seasonal average of 54 and 39% of males and females, respectively, were infected; whereas in 2004, 36 and 41% of male and female beetles, respectively, were infected. The percentage of males infected with H. virescens was correlated with the number of males captured at the site in 2003; infection rate decreased as male abundance increased. Infection rate did not correlate with female abundance in 2003 or male or female abundance in 2004. Host gender had a considerable effect on the density and distribution of the fungus. Hesperomyces virescens mature thalli were denser on male rather than female beetles. Also, thallus density was often greatest on the elytra, meso- and metathorax, and abdomen of males and elytra of females, than on other body parts, in 2003. In 2003 and 2004, approximately 59 and 97% and 67 and 96% of males and females, respectively, had mature thalli distributed on the elytra. Prevalence of H. virescens thalli on the dorsum of H. axyridis females suggests that mating behavior is important in fungal transmission. However, prevalence of thalli on the dorsum of H. axyridis males suggests that behaviors other than mating contribute to the transmission of H. virescens onto male beetles. Spread of H. virescens ascospores from infected to uninfected H. axyridis adults of different generations, at feeding sites, might be vital to maintaining stable populations of the fungus. PMID:20298119

Dynamical roguing model for controlling the spread of tungro virus via Nephotettix Virescens in a rice field

NASA Astrophysics Data System (ADS)

Blas, Nikki; David, Guido

2017-10-01

Rice tungro disease is described as a cancer due to its major impact on the livelihood of farmers and the difficulty of controlling it. Tungro is a semi-persistent virus transmitted by green leafhoppers called Nephotettix Virescens. In this paper, we presented a compartmental plant-vector model of the Nephotettix Virescens - rice plant interaction based on a system of ordinary differential equations to simulate the effects of roguing in controlling the spread of Tungro virus in a model rice field of susceptible rice variety (Taichung Native 1).

40 CFR 180.1027 - Nuclear polyhedrosis virus of Heliothis zea; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Nuclear polyhedrosis virus of... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1027 Nuclear polyhedrosis virus of... Heliothis zea nuclear polyhedrosis virus (HzSNPV). The identity of the seed virus must be assured by...

40 CFR 180.1027 - Nuclear polyhedrosis virus of Heliothis zea; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Nuclear polyhedrosis virus of... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1027 Nuclear polyhedrosis virus of... Heliothis zea nuclear polyhedrosis virus (HzSNPV). The identity of the seed virus must be assured by...

40 CFR 180.1027 - Nuclear polyhedrosis virus of Heliothis zea; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Nuclear polyhedrosis virus of... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1027 Nuclear polyhedrosis virus of... Heliothis zea nuclear polyhedrosis virus (HzSNPV). The identity of the seed virus must be assured by...

How many taxa can be recognized within the complex Tillandsia capillaris (Bromeliaceae, Tillandsioideae)? Analysis of the available classifications using a multivariate approach.

PubMed

Castello, Lucía V; Galetto, Leonardo

2013-01-01

Tillandsia capillaris Ruiz & Pav., which belongs to the subgenus Diaphoranthema is distributed in Ecuador, Peru, Bolivia, northern and central Argentina, and Chile, and includes forms that are difficult to circumscribe, thus considered to form a complex. The entities of this complex are predominantly small-sized epiphytes, adapted to xeric environments. The most widely used classification defines 5 forms for this complex based on few morphological reproductive traits: Tillandsia capillaris Ruiz & Pav. f. capillaris, Tillandsia capillaris f. incana (Mez) L.B. Sm., Tillandsia capillaris f. cordobensis (Hieron.) L.B. Sm., Tillandsia capillaris f. hieronymi (Mez) L.B. Sm. and Tillandsia capillaris f. virescens (Ruiz & Pav.) L.B. Sm. In this study, 35 floral and vegetative characters were analyzed with a multivariate approach in order to assess and discuss different proposals for classification of the Tillandsia capillaris complex, which presents morphotypes that co-occur in central and northern Argentina. To accomplish this, data of quantitative and categorical morphological characters of flowers and leaves were collected from herbarium specimens and field collections and were analyzed with statistical multivariate techniques. The results suggest that the last classification for the complex seems more comprehensive and three taxa were delimited: Tillandsia capillaris (=Tillandsia capillaris f. incana-hieronymi), Tillandsia virescens s. str. (=Tillandsia capillaris f. cordobensis) and Tillandsia virescens s. l. (=Tillandsia capillaris f. virescens). While Tillandsia capillaris and Tillandsia virescens s. str. co-occur, Tillandsia virescens s. l. is restricted to altitudes above 2000 m in Argentina. Characters previously used for taxa delimitation showed continuous variation and therefore were not useful. New diagnostic characters are proposed and a key is provided for delimiting these three taxa within the complex.

How many taxa can be recognized within the complex Tillandsia capillaris (Bromeliaceae, Tillandsioideae)? Analysis of the available classifications using a multivariate approach

PubMed Central

Castello, Lucía V.; Galetto, Leonardo

2013-01-01

Abstract Tillandsia capillaris Ruiz & Pav., which belongs to the subgenus Diaphoranthema is distributed in Ecuador, Peru, Bolivia, northern and central Argentina, and Chile, and includes forms that are difficult to circumscribe, thus considered to form a complex. The entities of this complex are predominantly small-sized epiphytes, adapted to xeric environments. The most widely used classification defines 5 forms for this complex based on few morphological reproductive traits: Tillandsia capillaris Ruiz & Pav. f. capillaris, Tillandsia capillaris f. incana (Mez) L.B. Sm., Tillandsia capillaris f. cordobensis (Hieron.) L.B. Sm., Tillandsia capillaris f. hieronymi (Mez) L.B. Sm. and Tillandsia capillaris f. virescens (Ruiz & Pav.) L.B. Sm. In this study, 35 floral and vegetative characters were analyzed with a multivariate approach in order to assess and discuss different proposals for classification of the Tillandsia capillaris complex, which presents morphotypes that co-occur in central and northern Argentina. To accomplish this, data of quantitative and categorical morphological characters of flowers and leaves were collected from herbarium specimens and field collections and were analyzed with statistical multivariate techniques. The results suggest that the last classification for the complex seems more comprehensive and three taxa were delimited: Tillandsia capillaris (=Tillandsia capillaris f. incana-hieronymi), Tillandsia virescens s. str. (=Tillandsia capillaris f. cordobensis) and Tillandsia virescens s. l. (=Tillandsia capillaris f. virescens). While Tillandsia capillaris and Tillandsia virescens s. str. co-occur, Tillandsia virescens s. l. is restricted to altitudes above 2000 m in Argentina. Characters previously used for taxa delimitation showed continuous variation and therefore were not useful. New diagnostic characters are proposed and a key is provided for delimiting these three taxa within the complex. PMID:23805053

Impact of mirid (Creontiades spp.) (Hemiptera: Miridae) pest management on Helicoverpa spp. (Lepidoptera: Noctuidae) outbreaks: the case for conserving natural enemies.

PubMed

Knight, Kristen M M; Brier, Hugh B; Lucy, Michael J; Kopittke, Rosemary A

2007-05-01

Creontiades spp. (Hemiptera: Miridae) are sucking pests that attack buds, flowers and young pods in mungbeans, Vigna radiata (L.), causing these structures subsequently to abort. If left uncontrolled, mirids can cause 25-50% yield loss. Traditional industry practice has involved prophylactic applications of dimethoate to control mirids at budding and again a week later. The present trial was initiated to highlight the dangers of such a practice, in particular the risk of a subsequent Helicoverpa spp. lepidopteran pest outbreak. A single application of dimethoate halved the population of important natural enemies of Helicoverpa spp., and caused an above-threshold outbreak of Helicoverpa spp. within 11 days. This shows that even a moderate (e.g. 50%) reduction in natural enemies may be sufficient to increase Helicoverpa spp. populations in mungbeans. As a result, prophylactic sprays should not be used for the control of mirids in mungbeans, and dimethoate should be applied only when mirids are above the economic threshold. Indoxacarb was also tested to establish its effect on Helicoverpa spp., mirids and natural enemies. Indoxacarb showed potential for Helicoverpa spp. control and suppression of mirids and had little impact on natural enemies.

Genomic basis for the pest status of two Helicoverpa species

USDA-ARS?s Scientific Manuscript database

Background: Helicoverpa armigera and Helicoverpa zea are major caterpillar pests of Old and New World agriculture respectively. Both, particularly H. armigera, are extremely polyphagous, and H. armigera has developed resistance to many insecticides. Here we use comparative and population genomics an...

Efficacy of Venom from Tentacle of Jellyfish Stomolophus meleagris (Nemopilema nomurai) against the Cotton Bollworm Helicoverpa armigera

PubMed Central

Yu, Huahua; Li, Rongfeng; Dong, Xiangli; Xing, Ronge; Liu, Song; Li, Pengcheng

2014-01-01

Efficacy of venom from tentacle of jellyfish Stomolophus meleagris against the cotton bollworm Helicoverpa armigera was determined. Venom from tentacle of jellyfish Stomolophus meleagris could inhibit the growth of Helicoverpa armigera and the weight inhibiting rate of sample NFr-2 was 60.53%. Of the six samples, only NFr-2 had high insecticidal activity against Helicoverpa armigera and the corrected mortality recorded at 7 d was 74.23%. PMID:25162008

Efficacy of Soybean’s Event DAS-81419-2 Expressing Cry1F and Cry1Ac to Manage Key Tropical Lepidopteran Pests Under Field Conditions in Brazil

PubMed Central

Marques, L H; Castro, B A; Rossetto, J; Silva, O A B N; Moscardini, V F; Zobiole, L H S; Santos, A C; Valverde-Garcia, P; Babcock, J M; Rule, D M; Fernandes, O A

2016-01-01

Abstract Bacillus thuringiensis (Bt) event DAS-81419-2 (Conkesta technology) in soybean, Glycine max (L.) Merrill, expresses Cry1F and Cry1Ac proteins to provide protection from feeding by several lepidopteran pests. A total of 27 field experiments across nine locations were conducted from 2011 to 2015 in southern and central Brazil to characterize the efficacy of DAS-81419-2 soybean infested with Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), Heliothis virescens (F.) (Lepidoptera: Noctuidae), and Spodoptera cosmioides (Walker) (Lepidoptera: Noctuidae) during vegetative (V4) and reproductive (R2 and R4) crop developmental stages. The efficacy of DAS-81419-2 was compared to that of a non-Bt isogenic variety managed with or without applications of commercial foliar insecticides for lepidopteran control. DAS-81419-2 soybean consistently experienced defoliation levels of 0.5% or less (compared with 20.05–56.74% in the non-Bt, nonsprayed treatment) and larval survival of < 0.1% in all four species across the vegetative and reproductive plant stages evaluated. The efficacy of DAS-81419-2 was significantly higher than commercial foliar insecticides applied to the non-Bt variety. DAS-81419-2 soybeans containing two highly effective Bt proteins are expected to be a more robust IRM tool compared to single-trait Bt technologies. The consistent efficacy of DAS-81419-2 soybeans across years, locations, and crop stages suggests that it will be a valuable product for management of hard-to-control key lepidopteran pests in South American soybean production. PMID:27401112

Moth Sex Pheromone Receptors and Deceitful Parapheromones

PubMed Central

Xu, Pingxi; Garczynski, Stephen F.; Atungulu, Elizabeth; Syed, Zainulabeuddin; Choo, Young-Moo; Vidal, Diogo M.; Zitelli, Caio H. L.; Leal, Walter S.

2012-01-01

The insect's olfactory system is so selective that male moths, for example, can discriminate female-produced sex pheromones from compounds with minimal structural modifications. Yet, there is an exception for this “lock-and-key” tight selectivity. Formate analogs can be used as replacement for less chemically stable, long-chain aldehyde pheromones, because male moths respond physiologically and behaviorally to these parapheromones. However, it remained hitherto unknown how formate analogs interact with aldehyde-sensitive odorant receptors (ORs). Neuronal responses to semiochemicals were investigated with single sensillum recordings. Odorant receptors (ORs) were cloned using degenerate primers, and tested with the Xenopus oocyte expression system. Quality, relative quantity, and purity of samples were evaluated by gas chromatography and gas chromatography-mass spectrometry. We identified olfactory receptor neurons (ORNs) housed in trichoid sensilla on the antennae of male navel orangeworm that responded equally to the main constituent of the sex pheromone, (11Z,13Z)-hexadecadienal (Z11Z13-16Ald), and its formate analog, (9Z,11Z)-tetradecen-1-yl formate (Z9Z11-14OFor). We cloned an odorant receptor co-receptor (Orco) and aldehyde-sensitive ORs from the navel orangeworm, one of which (AtraOR1) was expressed specifically in male antennae. AtraOR1•AtraOrco-expressing oocytes responded mainly to Z11Z13-16Ald, with moderate sensitivity to another component of the sex pheromone, (11Z,13Z)-hexadecadien-1-ol. Surprisingly, this receptor was more sensitive to the related formate than to the natural sex pheromone. A pheromone receptor from Heliothis virescens, HR13 ( = HvirOR13) showed a similar profile, with stronger responses elicited by a formate analog than to the natural sex pheromone, (11Z)-hexadecenal thus suggesting this might be a common feature of moth pheromone receptors. PMID:22911835

Gut transcription in Helicoverpa zea is dynamically altered in response to baculovirus infection

USDA-ARS?s Scientific Manuscript database

The Helicoverpa zea transcriptome was analyzed 24 hours after H. zea larvae fed on artificial diet laced with Helicoverpa zea single nucleopolyhedrovirus (HzSNPV). Significant differential regulation of 1,139 putative genes (P<0.05 T-test with Benjamini and Hochberg False Discovery Rate) was detect...

Comparative genomic sequence analysis of novel Helicoverpa armigera nucleopolyhedrovirus (NPV) isolated from Kenya and three other previously sequenced Helicoverpa spp. NPVs.

PubMed

Ogembo, Javier Gordon; Caoili, Barbara L; Shikata, Masamitsu; Chaeychomsri, Sudawan; Kobayashi, Michihiro; Ikeda, Motoko

2009-10-01

A newly cloned Helicoverpa armigera nucleopolyhedrovirus (HearNPV) from Kenya, HearNPV-NNg1, has a higher insecticidal activity than HearNPV-G4, which also exhibits lower insecticidal activity than HearNPV-C1. In the search for genes and/or nucleotide sequences that might be involved in the observed virulence differences among Helicoverpa spp. NPVs, the entire genome of NNg1 was sequenced and compared with previously sequenced genomes of G4, C1 and Helicoverpa zea single-nucleocapsid NPV (Hz). The NNg1 genome was 132,425 bp in length, with a total of 143 putative open reading frames (ORFs), and shared high levels of overall amino acid and nucleotide sequence identities with G4, C1 and Hz. Three NNg1 ORFs, ORF5, ORF100 and ORF124, which were shared with C1, were absent in G4 and Hz, while NNg1 and C1 were missing a homologue of G4/Hz ORF5. Another three ORFs, ORF60 (bro-b), ORF119 and ORF120, and one direct repeat sequence (dr) were unique to NNg1. Relative to the overall nucleotide sequence identity, lower sequence identities were observed between NNg1 hrs and the homologous hrs in the other three Helicoverpa spp. NPVs, despite containing the same number of hrs located at essentially the same positions on the genomes. Differences were also observed between NNg1 and each of the other three Helicoverpa spp. NPVs in the diversity of bro genes encoded on the genomes. These results indicate several putative genes and nucleotide sequences that may be responsible for the virulence differences observed among Helicoverpa spp., yet the specific genes and/or nucleotide sequences responsible have not been identified.

A mathematical model of transmission of rice tungro disease by Nephotettix Virescens

NASA Astrophysics Data System (ADS)

Blas, Nikki T.; Addawe, Joel M.; David, Guido

2016-11-01

One of the major threats in rice agriculture is the Tungro virus, which is transmitted semi-persistently to rice plants via green rice leafhoppers called Nephotettix Virescens. Tungro is polycyclic and complex disease of rice associated by dual infection with Rice Tungro Bacilliform Virus (RTBV) and Rice Tungro Spherical Virus (RTSV). Interaction of the two viruses results in the degeneration of the host. In this paper, we used a plant-vector system of ordinary differential equations to model the spread of the disease in a model rice field. Parameter values were obtained from studies on the entomology of Nephotettix Virescens and infection rates of RTSV and RTBV. The system was analyzed for equilibrium solutions, and solved numerically for susceptible rice varieties (Taichung Native 1).

Combining Tpi and CO1 genetic markers to discriminate invasive Helicoverpa armigera from local Helicoverpa zea (Lepidoptera:Noctuidae) populations in the southeastern United States

USDA-ARS?s Scientific Manuscript database

The recent establishment of the Old World pest Helicoverpa armigera into South America has had significant economic consequences and places the rest of the hemisphere at risk, emphasizing the need for improved methods of monitoring. A major complication is that a sibling species endemic to the New W...

Cytogenetic studies in Eigenmannia virescens (Sternopygidae, Gymnotiformes) and new inferences on the origin of sex chromosomes in the Eigenmannia genus

PubMed Central

2009-01-01

Background Cytogenetic studies were carried out on samples of Eigenmannia virescens (Sternopygidae, Gymnotiformes) obtained from four river systems of the Eastern Amazon region (Para, Brazil). Results All four populations had 2n = 38, with ZZ/ZW sex chromosomes (Z, acrocentric; W, submetacentric). Constitutive heterochromatin (CH) was found at the centromeric regions of all chromosomes. The W chromosome had a heterochromatic block in the proximal region of the short arm; this CH was positive for DAPI staining, indicating that it is rich in A-T base pairs. The nucleolar organizer region (NOR) was localized to the short arm of chromosome pair 15; this result was confirmed by fluorescent in situ hybridization (FISH) with human 45S rDNA, and CMA3 staining indicated that the region is G-C rich. FISH with telomeric probes did not show any evidence of interstitial telomeric sequences (ITS). Conclusion Previous studies have shown that the species Eigenmannia sp. 2 and E. virescens have differentiated sex chromosomes, and diverse sex chromosome systems have been described for E. virescens specimens obtained from different Brazilian rivers. A comparative analysis of the present data and prior reports suggests that the sex chromosomes of Eigenmannia may have arisen independently in the different populations. PMID:19930594

Development of a Microbial-Based Integrated Pest Management Program for Helicoverpa spp. (Lepidoptera: Noctuidae) and Beneficial Insects on Conventional Cotton Crops in Australia

PubMed Central

Mensah, Robert K.; Young, Alison; Rood-England, Leah

2015-01-01

Entomopathogenic fungi, when used as a microbial control agent against cotton pests, such as Helicoverpa spp., may have the potential to establish and spread in the environment and to have an impact on both pests and beneficial insects. Information on the effect of entomopathogenic fungi on pests and beneficial insects is crucial for a product to be registered as a biopesticide. The effect of the entomopathogenic fungus BC 639 (Aspergillus sp.) against Helicoverpa spp. and beneficial insects (mostly predatory insects) was studied in the laboratory and in cotton field trials. The results show that when Helicoverpa spp. second instar larvae were exposed to increasing concentrations (from 102 to 109) of the entomopathogenic fungus BC 639, the optimum dose required to kill over 50% of the insects was 1.0 × 107 spores/mL. In the field trials, the number of Helicoverpa spp. per metre on plots treated with 1.0 or 0.50 L/ha of BC 639 was the same as on plots treated with the recommended rate of the commercial insecticide, Indoxacarb. However, when plots were treated with 0.25 L/ha of BC 639, this was not as effective at controlling Helicoverpa spp. as 1.0 or 0.5 L/ha BC 639 or Indoxacarb. BC 639 had less effect on predatory insects when applied at lower rates (0.50 and 0.25 L/ha) than at higher rates (1.0 L/ha). Thus, BC 639 was more selective against predators when applied at lower rates than at the higher rate, but was also more selective than Indoxacarb. Thus, the ability of BC 639 to control Helicoverpa spp. effectively with a minimal effect on predatory insects indicates its potential for enhancing integrated pest management programs and to sustain cotton production. PMID:26463189

Monoclonal Antibody Analysis and Insecticidal Spectrum of Three Types of Lepidopteran-Specific Insecticidal Crystal Proteins of Bacillus thuringiensis

PubMed Central

Höfte, Herman; Van Rie, Jeroen; Jansens, Stefan; Van Houtven, Annemie; Vanderbruggen, Hilde; Vaeck, Mark

1988-01-01

We have investigated the protein composition and the insecticidal spectrum of crystals of 29 Bacillus thuringiensis strains active against lepidopteran larvae. All crystals contained proteins of 130 to 140 kilodaltons (kDa) which could be grouped into three types by the molecular weight of the protoxin and the trypsin-activated core fragment. Proteins of the three types showed a characteristic insecticidal spectrum when tested against five lepidopteran species. Type A crystal proteins were protoxins of 130 or 133 kDa, which were processed into 60-kDa toxins by trypsin. Several genes encoding crystal proteins of this type have been cloned and sequenced earlier. They are highly conserved in the N-terminal half of the toxic fragment and were previously classified in three subtypes (the 4.5-, 5.3-, and 6.6-kilobase subtypes) based on the restriction map of their genes. The present study shows that different proteins of these three subtypes were equally toxic against Manduca sexta and Pieris brassicae and had no detectable activity against Spodoptera littoralis. However, the 4.5-, 5.3-, and 6.6-kilobase subtypes differed in their toxicity against Heliothis virescens and Mamestra brassicae. Type B crystal proteins consisted of 140-kDa protoxins with a 55-kDa tryptic core fragment. These were only active against one of the five insect species tested (P. brassicae). The protoxin and the trypsin-activated toxin of type C were 135- and 63-kDa proteins, respectively. Proteins of this type were associated with high toxicity against S. littoralis and M. brassicae. A panel of 35 monoclonal antibodies was used to compare the structural characteristics of crystal proteins of the three different types and subtypes. Each type of protein could be associated with a typical epitope structure, indicating an unambiguous correlation between antigenic structure and insect specificity. Images PMID:16347711

Sex-Linked Pheromone Receptor Genes of the European Corn Borer, Ostrinia nubilalis, Are in Tandem Arrays

PubMed Central

Yasukochi, Yuji; Miura, Nami; Nakano, Ryo; Sahara, Ken; Ishikawa, Yukio

2011-01-01

Background Tuning of the olfactory system of male moths to conspecific female sex pheromones is crucial for correct species recognition; however, little is known about the genetic changes that drive speciation in this system. Moths of the genus Ostrinia are good models to elucidate this question, since significant differences in pheromone blends are observed within and among species. Odorant receptors (ORs) play a critical role in recognition of female sex pheromones; eight types of OR genes expressed in male antennae were previously reported in Ostrinia moths. Methodology/Principal Findings We screened an O. nubilalis bacterial artificial chromosome (BAC) library by PCR, and constructed three contigs from isolated clones containing the reported OR genes. Fluorescence in situ hybridization (FISH) analysis using these clones as probes demonstrated that the largest contig, which contained eight OR genes, was located on the Z chromosome; two others harboring two and one OR genes were found on two autosomes. Sequence determination of BAC clones revealed the Z-linked OR genes were closely related and tandemly arrayed; moreover, four of them shared 181-bp direct repeats spanning exon 7 and intron 7. Conclusions/Significance This is the first report of tandemly arrayed sex pheromone receptor genes in Lepidoptera. The localization of an OR gene cluster on the Z chromosome agrees with previous findings for a Z-linked locus responsible for O. nubilalis male behavioral response to sex pheromone. The 181-bp direct repeats might enhance gene duplications by unequal crossovers. An autosomal locus responsible for male response to sex pheromone in Heliothis virescens and H. subflexa was recently reported to contain at least four OR genes. Taken together, these findings support the hypothesis that generation of additional copies of OR genes can increase the potential for male moths to acquire altered specificity for pheromone components, and accordingly, facilitate differentiation of sex pheromones. PMID:21526121

Molecular evolution of the odorant and gustatory receptor genes in lepidopteran insects: implications for their adaptation and speciation.

PubMed

Engsontia, Patamarerk; Sangket, Unitsa; Chotigeat, Wilaiwan; Satasook, Chutamas

2014-08-01

Lepidoptera (comprised of butterflies and moths) is one of the largest groups of insects, including more than 160,000 described species. Chemoreception plays important roles in the adaptation of these species to a wide range of niches, e.g., plant hosts, egg-laying sites, and mates. This study investigated the molecular evolution of the lepidopteran odorant (Or) and gustatory receptor (Gr) genes using recently identified genes from Bombyx mori, Danaus plexippus, Heliconius melpomene, Plutella xylostella, Heliothis virescens, Manduca sexta, Cydia pomonella, and Spodoptera littoralis. A limited number of cases of large lineage-specific gene expansion are observed (except in the P. xylostella lineage), possibly due to selection against tandem gene duplication. There has been strong purifying selection during the evolution of both lepidopteran odorant and gustatory genes, as shown by the low ω values estimated through CodeML analysis, ranging from 0.0093 to 0.3926. However, purifying selection has been relaxed on some amino acid sites in these receptors, leading to sequence divergence, which is a precursor of positive selection on these sequences. Signatures of positive selection were detected only in a few loci from the lineage-specific analysis. Estimation of gene gains and losses suggests that the common ancestor of the Lepidoptera had fewer Or genes compared to extant species and an even more reduced number of Gr genes, particularly within the bitter receptor clade. Multiple gene gains and a few gene losses occurred during the evolution of Lepidoptera. Gene family expansion may be associated with the adaptation of lepidopteran species to plant hosts, especially after angiosperm radiation. Phylogenetic analysis of the moth sex pheromone receptor genes suggested that chromosomal translocations have occurred several times. New sex pheromone receptors have arisen through tandem gene duplication. Positive selection was detected at some amino acid sites predicted to be in the extracellular and transmembrane regions of the newly duplicated genes, which might be associated with the evolution of the new pheromone receptors.

Intraguild interactions and behavior of Spodoptera frugiperda and Helicoverpa spp. on maize.

PubMed

Bentivenha, José Pf; Montezano, Débora G; Hunt, Thomas E; Baldin, Edson Ll; Peterson, Julie A; Victor, Vinícius S; Pannuti, Luiz Er; Vélez, Ana M; Paula-Moraes, Silvana V

2017-11-01

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is one of the major pests of maize and is in the same feeding guild as the noctuid pests Helicoverpa zea (Boddie) and Helicoverpa armigera (Hübner), recently reported in South and North America. The intraguild interactions of these species were assessed in laboratory and field conditions by determining the survival of larvae in interaction scenarios with non-Bt maize silks and ears. Moreover, a video tracking system was utilized to evaluate behavioral parameters during larval interactions in scenarios with or without food. In intraguild interactions, S. frugiperda had greater survival (55-100%) when competing with Helicoverpa spp. in scenarios where larvae were the same instar or when they were larger (fourth versus second) than their competitor. Frequency and time in food of S. frugiperda larvae were negatively influenced by interactions. Larvae of S. frugiperda moved shorter distances (less than 183.03 cm) compared with H. zea. Overall, S. frugiperda had a competitive advantage over Helicoverpa spp. This study provides significant information regarding noctuid behavior and larval survival during intraguild interactions, which may impact pest prevalence and population dynamics, thereby affecting integrated pest management and insect resistance management of these species in maize. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Cold hardiness of Helicoverpa zea (Lepidoptera: Noctuidae) pupae

Treesearch

A.C. Morey; W.D. Hutchison; R.C. Venette; E.C. Burkness

2012-01-01

An insect's cold hardiness affects its potential to overwinter and outbreak in different geographic regions. In this study, we characterized the response of Helicoverpa zea (Boddie) pupae to low temperatures by using controlled laboratory measurements of supercooling point (SCP), lower lethal temperature (LT50), and lower...

Unique synteny and alternate splicing of the chitin synthases in closely related heliothine moths

USDA-ARS?s Scientific Manuscript database

Two chitin synthase genes were characterized in the genomes of two heliothine moths: the corn earworm/cotton bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) and the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). In both moths, the coding sequences for the two ge...

Infection of Helicoverpa armigera by endophytic Beauveria bassiana colonizing tomato plants

USDA-ARS?s Scientific Manuscript database

A novel endophytic strain of Beauveria bassiana was isolated from leaf tissue of a wild tomato plant. This strain and two B. bassiana strains previously isolated from soil were evaluated for their ability to endophytically colonize tomatoes and subsequent in planta efficacy against Helicoverpa armig...

Effect of Hexaflumuron on feeding response and reproduction of bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)

USDA-ARS?s Scientific Manuscript database

Hexaflumuron (Consult® 100 EC, Dow AgroSciences) is an insect growth regulator that inhibits chitin synthesis. The efficacy of hexaflumuron mixed with 2.5 M sucrose (ppm) was evaluated in the laboratory against bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) for toxicity, proboscis exten...

Heliothis subflexa (Gn.) (Lepidoptera: Noctuidae): Demonstration of oviposition stimulant from groundcherry using novel bioassay.

PubMed

Mitchell, E R; Heath, R R

1987-08-01

Methanol extracts of homogenized groundcherry,Physalis angulata, leaves increased egg deposition byHeliothis subflexa (Gn.) (HS) on treated tobacco plants (a nonhost) 8.5-fold over untreated controls. In doseresponse tests using whole-leaf washes of groundcherry leaves, the threshold of positive response vs. no response to the chemical stimulant was within one log dose unit when compared to the controls. This response was consistent whether the chemical was evaluated on plants in greenhouse-cage tests or in an olfactometer using pieces of broadcloth as the oviposition substrate. The olfactometer used allows year-round study of the behavioral effects of plant allelochemics on insect oviposition behavior in a controlled environment.

Prediction of cotton resistance to Helicoverpa armigera based on the percent (+)-gossypol in mature seed

USDA-ARS?s Scientific Manuscript database

Various Uzbek commercial varieties were grown in the field and these were exposed to cotton bollworm (Helicoverpa armigera) larvae. A significant negative correlation coefficient (r = -0.89) and linear regression (Y = 109.69-5.26X) was observed between the concentration of (+)-gossypol in cotton se...

Effect of emamectin benzoate on mortality, proboscis extension, gustation and reproduction of the corn earworm, Helicoverpa zea

USDA-ARS?s Scientific Manuscript database

Newly emerged bollworm adults, Helicoverpa zea (Boddie) require carbohydrate source from plant exudates and nectars for reproduction. Adults actively seek such feeding sites upon eclosion in their natural habitat. We wanted to evaluate this nocturnal behavior of the bollworm for potential use as a p...

Integrating immunomarking with ecological and behavioural approaches to assess predation of Helicoverpa spp. larvae by wolf spiders in cotton

USDA-ARS?s Scientific Manuscript database

Wolf spiders (Araneae: Lycosidae) are abundant soil-dwelling predators found in cotton fields and can contribute important pest management services. These spiders can kill and consume larvae of the cotton bollworm Helicoverpa spp. (Lepidoptera: Noctuidae) that survive foraging on Bt cotton and desce...

Long distance migration in Helicoverpa zea: What we know and need to know

USDA-ARS?s Scientific Manuscript database

This paper identifies knowledge and knowledge gaps in the areas of biology and ecology, and migratory flight of corn earworm, Helicoverpa zea (Boddie). The paper focuses on results from studies of H. zea population dynamics and migration in Texas during a period of substantial irrigated corn produc...

Intra- and extracellular domains of the Helicoverpa armigera cadherin mediate Cry1Ac cytotoxicity

USDA-ARS?s Scientific Manuscript database

Diverse midgut cadherin mutations confer resistance to Cry1A toxins in at least three lepidopteran pests, including the cotton bollworm, Helicoverpa armigera. Most of these cadherin mutations are inherited as recessive alleles and result in changes within the cadherin repeat (CR) regions of the extr...

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...

Molecular cloning and functional characterization of the diapause hormone receptor in the corn earworm Helicoverpa zea

USDA-ARS?s Scientific Manuscript database

The diapause hormone (DH) in the heliothine moth has shown its activity in termination of pupal diapause, while the orthology in the silkworm is known to induce embryonic diapause. In the current study, we cloned the diapause hormone receptor from the corn earworm Helicoverpa zea (HzDHr) and tested ...

Complete mitochondrial genome of Helicoverpa zea (Boddie) and expression profiles of mitochondrial-encoded genes in early and late embryos

USDA-ARS?s Scientific Manuscript database

The mitochondrial genome of the bollworm, Helicoverpa zea, was assembled using paired-end nucleotide sequence reads generated with a next-generation sequencing platform. Assembly resulted in a mitogenome of 15,348 bp with greater than 17,000-fold average coverage. Organization of the H. zea mitogen...

A droplet digital PCR (ddPCR) assay to detect Helicoverpa armigera (Lepidoptera: Noctuidae) in bulk trap samples

USDA-ARS?s Scientific Manuscript database

Moths in the genus Helicoverpa are some of the most important agricultural pests in the world. Two species, H. armigera (Hübner) and H. zea (Boddie), cause the majority of damage to crops and millions of dollars are spent annually on control of these pests. The recent introduction of H. armigera int...

Genomic Sequences of Five Helicoverpa armigera Nucleopolyhedrovirus Genotypes from Spain That Differ in Their Insecticidal Properties

PubMed Central

Arrizubieta, Maite; Williams, Trevor; Caballero, Primitivo

2015-01-01

Helicoverpa armigera nucleopolyhedrovirus (HearNPV) has proved effective as the basis for various biological insecticides. Complete genome sequences of five Spanish HearNPV genotypes differed principally in the homologous regions (hrs) and the baculovirus repeat open reading frame (bro) genes, suggesting that they may be involved in the phenotypic differences observed among genotypes. PMID:26067949

Genome Sequence of Acinetobacter sp. Strain HA, Isolated from the Gut of the Polyphagous Insect Pest Helicoverpa armigera

PubMed Central

Malhotra, Jaya; Dua, Ankita; Saxena, Anjali; Sangwan, Naseer; Mukherjee, Udita; Pandey, Neeti; Rajagopal, Raman; Khurana, Paramjit; Khurana, Jitendra P.

2012-01-01

In this study, Acinetobacter sp. strain HA was isolated from the midgut of a fifth-instar larva of Helicoverpa armigera. Here, we report the draft genome sequence (3,125,085 bp) of this strain that consists of 102 contigs, 2,911 predicted coding sequences, and a G+C content of 41%. PMID:22933775

Comparative host selection responses of specialist (Helicoverpa assulta) and generalist (Helicoverpa armigera) moths in complex plant environments

PubMed Central

Li, Wei-zheng; Teng, Xiao-hui; Zhang, Hong-fei; Liu, Ting; Wang, Qiong; Guo, Xian-ru

2017-01-01

We tested the behavioral responses of ovipositing females and natal larvae of two sibling species, a generalist Helicoverpa armigera (Hübner) and a specialist Helicoverpa assulta (Guenée), to odor sources emitted from different combinations of six plant species (tobacco, Nicotiana tabacum; hot pepper, Capsicum annuum; tomato, Solanum esculentum; cotton, Gossypium hirsutum; peanut, Arachis hypogaea; maize, Zea mays). Under the conditions of plant materials versus corresponding controls, both stages of both species could find their corresponding host plants. However, H. assulta females and larvae exhibited a supersensitive and an insensitive response, respectively. Under the conditions of tobacco paired with each plant species, H. assulta females exhibited more specialized ovipositional response to tobacco than its sibling. When each plant species were combined with tobacco and tested against tobacco reference, peanut played an opposite role in the two species in their ovipositional responses to tobacco, and cotton can enhance the approaching response of H. armigera larvae when combined with tobacco. It seems that two attractive host plants also can act antagonistically with respect to host selection of the generalist via volatile exchange. Tomato should better be excluded from host list of H. assulta. PMID:28182679

Flight response ofHeliothis subflexa (Gn.) females (Lepidoptera: Noctuidae) to an attractant from groundcherry,Physalis angulata L.

PubMed

Tingle, F C; Heath, R R; Mitchell, E R

1989-01-01

Mated femaleHeliothis subflexa (Gn.) (HS) moths 1-7 days old responded positively in a Plexiglas flight tunnel to an attractant extracted with methanol from fresh whole-leaf washes of groundcherry,Physalis angulata L. Response to the groundcherry extract, as indicated by plume-tracking (i.e., upwind flight toward the odor source) and contact with the chemical dispenser did not change significantly during the first 5 hr of scotophase. Overall, ca. 50% of the responding moths also landed on the chemical dispenser; ca. 50% of the moths that landed also deposited eggs. There were no significant differences in the behavioral responses of females mating only once and those that had mated two or more times. Virgin females and male moths were significantly less responsive to the groundcherry attractant than mated females. The flight tunnel bioassay described provides an excellent system for evaluating plant allelochemics associated with host-plant selection.

Physiological and Molecular Characterization of Cephaleuros virescens Occurring in Mango Trees.

PubMed

Vasconcelos, Camila Vilela; Pereira, Fabíola Teodoro; Duarte, Elizabeth Amélia Alves; de Oliveira, Thiago Alves Santos; Peixoto, Nei; Carvalho, Daniel Diego Costa

2018-06-01

The objective of this work was to accomplish the isolation, molecular identification and characterizing the physiology of the causal agent of the algal spot in mango trees. For this purpose, the pathogen growth was assessed in different culture media, with subsequent observation and measurements of the filamentous cells. The molecular identification was made using mycelium obtained from leaf lesions and pure algae colonies grown in culture medium. Descriptions based on DNA sequencing indicated that the algae is Cephaleuros virescens . The algae must be isolated primarily in liquid medium for further pricking into agar medium. The highest mycelial growth average in Petri dishes occurred when the algae were grown in Trebouxia and BBM. Trebouxia enabled larger cells in the filamentous cells when compared to other culture media.

40 CFR 180.1027 - Nuclear polyhedrosis virus of Heliothis zea; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1027 Nuclear polyhedrosis virus of... should not exceed 107 colonies per gram as determined by an aerobic plate on trypticase soy agar. (2...

40 CFR 180.1027 - Nuclear polyhedrosis virus of Heliothis zea; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1027 Nuclear polyhedrosis virus of... should not exceed 107 colonies per gram as determined by an aerobic plate on trypticase soy agar. (2...

50 CFR 665.401 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Lehi/maroobw red snapper, silvermouth Aphareus rutilans. Gogunafon/aiwe gray snapper, jobfish Aprion virescens. Tarakitu/etam Giant trevally, jack Caranx ignobilis. Tarakiton attelong/orong Black trevally... grouper Variola louti. Buninas agaga'/falaghal moroobw red snapper Etelis carbunculus. Abuninas...

50 CFR 665.401 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Lehi/maroobw red snapper, silvermouth Aphareus rutilans. Gogunafon/aiwe gray snapper, jobfish Aprion virescens. Tarakitu/etam Giant trevally, jack Caranx ignobilis. Tarakiton attelong/orong Black trevally... grouper Variola louti. Buninas agaga'/falaghal moroobw red snapper Etelis carbunculus. Abuninas...

50 CFR 665.401 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Lehi/maroobw red snapper, silvermouth Aphareus rutilans. Gogunafon/aiwe gray snapper, jobfish Aprion virescens. Tarakitu/etam Giant trevally, jack Caranx ignobilis. Tarakiton attelong/orong Black trevally... grouper Variola louti. Buninas agaga'/falaghal moroobw red snapper Etelis carbunculus. Abuninas...

A rapid method for the identification and differentiation of Helicoverpa nucleopolyhedroviruses (NPV Baculoviridae) isolated from the environment.

PubMed

Christian, P D; Gibb, N; Kasprzak, A B; Richards, A

2001-07-01

A diagnostic method is described for the identification and differentiation of nucleopolyhedrovirus (NPV) pathogens of Helicoverpa species (Lepidoptera: Noctuidae) isolated from the environment. The method is based on the polymerase chain reaction (PCR) used in conjunction with restriction fragment length polymorphism (RFLP) analysis and comprises three parts. The first part describes procedures for obtaining PCR quality viral DNA from individual diseased H. armigera cadavers recovered during bioassay analyses of soil and other types of environmental sample. These procedures were modified from standard techniques used for the routine purification and dissolution of NPV polyhedra and provided an overall PCR success rate of 95% (n=60). The second part describes the design of several sets of PCR primers for generating DNA amplification products from closely and distantly related NPVs. These PCR primers were designed from published DNA sequence data and from randomly cloned genomic DNA fragments isolated from a reference H. armigera SNPV (HaSNPV) isolate. The final part of the method describes how specific PCR products when digested with specific restriction endonuclease enzymes, can be used to generate diagnostic DNA profiles (haplotypes) that can be used both to identify heterologous NPVs e.g. Autographa californica MNPV and related viruses, and to differentiate genotypic variants of Helicoverpa SNPV. In the latter case, only two PCR products and four restriction digests were required to differentiate a reference set of 10 Helicoverpa SNPV isolates known to differ 0.1--3.5% at the nucleotide level. The diagnostic method described below marks the second part of a two-phase quantitative-diagnostic protocol that is now being applied to a variety of ecological investigations. In particular, its application should lead to a significant improvement in our understanding of the distribution and population genetics of Helicoverpa SNPVs in the Australian environment, as well as providing a sound basis for the design of pre- and post-release monitoring systems for genetically enhanced bioinsecticides. It is also likely that this method can be adapted readily to the study of other insect pathogen associations important economically.

Biostable beta-amino acid PK/PBAN analogs: Agonist and antagonist properties

USDA-ARS?s Scientific Manuscript database

The pyrokinin/pheromone biosynthesis activating neuropeptide (PK/PBAN) family plays a significant role in a multifunctional array of important physiological processes in insects. PK/PBAN analogs incorporating beta-amino acids were synthesized and evaluated in a pheromonotropic assay in Heliothis pe...

Predicting the timing and potential of the spring emergence of overwintered populations of Heliothis spp

NASA Technical Reports Server (NTRS)

Hartstack, A. W.; Witz, J. A.; Lopez, J. D. (Principal Investigator)

1981-01-01

The current state of knowledge dealing with the prediction of the overwintering population and spring emergence of Heliothis spp., a serious pest of numerous crops is surveyed. Current literature is reviewed in detail. Temperature and day length are the primary factors which program H. spp. larva for possible diapause. Although studies on the interaction of temperature and day length are reported, the complete diapause induction process is not identified sufficiently to allow accurate prediction of diapause timing. Mortality during diapause is reported as highly variable. The factors causing mortality are identified, but only a few are quantified. The spring emergence of overwintering H. spp. adults and mathematical models which predict the timing of emergence are reviewed. Timing predictions compare favorably to observed field data; however, prediction of actual numbers of emerging moths is not possible. The potential for use of spring emergence predictions in pest management applications, as an early warning of potential crop damage, are excellent. Research requirements to develop such an early warning system are discussed.

50 CFR 665.101 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

... palu-gutusiliva red snapper, silvermouth Aphareus rutilans. asoama gray snapper, jobfish Aprion virescens. sapoanae giant trevally, jack Caranx ignobilis. tafauli black trevally, jack Caranx lugubris. fausi blacktip grouper Epinephelus fasciatus. papa, velo lunartail grouper Variola louti. palu malau red...

50 CFR 665.101 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... palu-gutusiliva red snapper, silvermouth Aphareus rutilans. asoama gray snapper, jobfish Aprion virescens. sapoanae giant trevally, jack Caranx ignobilis. tafauli black trevally, jack Caranx lugubris. fausi blacktip grouper Epinephelus fasciatus. papa, velo lunartail grouper Variola louti. palu malau red...

50 CFR 665.101 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... palu-gutusiliva red snapper, silvermouth Aphareus rutilans. asoama gray snapper, jobfish Aprion virescens. sapoanae giant trevally, jack Caranx ignobilis. tafauli black trevally, jack Caranx lugubris. fausi blacktip grouper Epinephelus fasciatus. papa, velo lunartail grouper Variola louti. palu malau red...

50 CFR 665.101 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... palu-gutusiliva red snapper, silvermouth Aphareus rutilans. asoama gray snapper, jobfish Aprion virescens. sapoanae giant trevally, jack Caranx ignobilis. tafauli black trevally, jack Caranx lugubris. fausi blacktip grouper Epinephelus fasciatus. papa, velo lunartail grouper Variola louti. palu malau red...

Untersuchungen zum Vorkommen von Myxobakterien in von Meerwasser beeinflußten Substraten unter besonderer Berücksichtigung der Insel Helgoland

NASA Astrophysics Data System (ADS)

Rückert, G.

1984-03-01

Representatives of the family Myxococcaceae, Myxococcus fulvus and M. virescens as well as Archangium gephyra could be isolated from marine sediments (depth range 5 58 m), collected near the island of Helgoland (North Sea); dunes and rudiments of salt marshes additionally yielded M. coralloides and the rare species Melittangium licenicola and M. boletus (Cystobacteriaceae). In soil samples from the island, M. fulvus, M. virescens, M. coralloides, A. gephyra, Cystobacter fuscus and Stigmatella erecta were found. These results were confirmed by data, obtained from the coastal zone of the island of Amrum and marine sediments from various regions. On the other hand samples from shallow fresh water (depth range 0.3 1 m) proved to be richer in species. It is assumed that the myxobacteria found in marine sediments occur as resting cells.

Two single-point mutations shift the ligand selectivity of a pheromone receptor between two closely related moth species

PubMed Central

Yang, Ke; Huang, Ling-Qiao; Ning, Chao

2017-01-01

Male moths possess highly sensitive and selective olfactory systems that detect sex pheromones produced by their females. Pheromone receptors (PRs) play a key role in this process. The PR HassOr14b is found to be tuned to (Z)−9-hexadecenal, the major sex-pheromone component, in Helicoverpa assulta. HassOr14b is co-localized with HassOr6 or HassOr16 in two olfactory sensory neurons within the same sensilla. As HarmOr14b, the ortholog of HassOr14b in the closely related species Helicoverpa armigera, is tuned to another chemical (Z)−9-tetradecenal, we study the amino acid residues that determine their ligand selectivity. Two amino acids located in the intracellular domains F232I and T355I together determine the functional difference between the two orthologs. We conclude that species-specific changes in the tuning specificity of the PRs in the two Helicoverpa moth species could be achieved with just a few amino acid substitutions, which provides new insights into the evolution of closely related moth species. PMID:29063835

Antennal transcriptome analysis and comparison of olfactory genes in two sympatric defoliators, Dendrolimus houi and Dendrolimus kikuchii (Lepidoptera: Lasiocampidae).

PubMed

Zhang, Sufang; Zhang, Zhen; Wang, Hongbin; Kong, Xiangbo

2014-09-01

The Yunnan pine and Simao pine caterpillar moths, Dendrolimus houi Lajonquière and Dendrolimus kikuchii Matsumura (Lepidoptera: Lasiocampidae), are two closely related and sympatric pests of coniferous forests in southwestern China, and olfactory communication systems of these two insects have received considerable attention because of their economic importance. However, there is little information on the molecular aspect of odor detection about these insects. Furthermore, although lepidopteran species have been widely used in studies of insect olfaction, few work made comparison between sister moths on the olfactory recognition mechanisms. In this study, next-generation sequencing of the antennal transcriptome of these two moths were performed to identify the major olfactory genes. After comparing the antennal transcriptome of these two moths, we found that they exhibit highly similar transcripts-associated GO terms. Chemosensory gene families were further analyzed in both species. We identified 23 putative odorant binding proteins (OBP), 17 chemosensory proteins (CSP), two sensory neuron membrane proteins (SNMP), 33 odorant receptors (OR), and 10 ionotropic receptors (IR) in D. houi; and 27 putative OBPs, 17 CSPs, two SNMPs, 33 ORs, and nine IRs in D. kikuchii. All these transcripts were full-length or almost full-length. The predicted protein sequences were compared with orthologs in other species of Lepidoptera and model insects, including Bombyx mori, Manduca sexta, Heliothis virescens, Danaus plexippus, Sesamia inferens, Cydia pomonella, and Drosophila melanogaster. The sequence homologies of the orthologous genes in D. houi and D. kikuchii are very high. Furthermore, the olfactory genes were classed according to their expression level, and the highly expressed genes are our target for further function investigation. Interestingly, many highly expressed genes are ortholog gene of D. houi and D. kikuchii. We also found that the Classic OBPs were further separated into three groups according to their motifs, which will help future functional researches. Surprisingly, no pheromone receptor was identified in the two Dendrolimus species, which may indicate a special pheromone identification mechanism in Dendrolimus. Our work allows for further functional studies of pheromones and host volatile recognition genes, and give novel candidate targets for pest management. Copyright © 2014 Elsevier Ltd. All rights reserved.

The genetic architecture of ecological adaptation: intraspecific variation in host plant use by the lepidopteran crop pest Chloridea virescens.

PubMed

Oppenheim, Sara J; Gould, Fred; Hopper, Keith R

2018-03-01

Intraspecific variation in ecologically important traits is a cornerstone of Darwin's theory of evolution by natural selection. The evolution and maintenance of this variation depends on genetic architecture, which in turn determines responses to natural selection. Some models suggest that traits with complex architectures are less likely to respond to selection than those with simple architectures, yet rapid divergence has been observed in such traits. The simultaneous evolutionary lability and genetic complexity of host plant use in the Lepidopteran subfamily Heliothinae suggest that architecture may not constrain ecological adaptation in this group. Here we investigate the response of Chloridea virescens, a generalist that feeds on diverse plant species, to selection for performance on a novel host, Physalis angulata (Solanaceae). P. angulata is the preferred host of Chloridea subflexa, a narrow specialist on the genus Physalis. In previous experiments, we found that the performance of C. subflexa on P. angulata depends on many loci of small effect distributed throughout the genome, but whether the same architecture would be involved in the generalist's adoption of P. angulata was unknown. Here we report a rapid response to selection in C. virescens for performance on P. angulata, and establish that the genetic architecture of intraspecific variation is quite similar to that of the interspecific differences in terms of the number, distribution, and effect sizes of the QTL involved. We discuss the impact of genetic architecture on the ability of Heliothine moths to respond to varying ecological selection pressures.

The entomopathogenic fungus Nomuraea rileyi impairs cellular immunity of its host Helicoverpa armigera.

PubMed

Zhong, Ke; Liu, Zhan-Chi; Wang, Jia-Lin; Liu, Xu-Sheng

2017-09-01

In this study, we investigated the effect of the entomopathogenic fungus Nomuraea rileyi on Helicoverpa armigera cellular immune responses. Nomuraea rileyi infection had no effect on total hemocyte count (THC), but impaired hemocyte-mediated phagocytosis, nodulation, and encapsulation responses. Nomuraea rileyi infection led to a significant reduction in hemocyte spreading. An in vitro assay revealed that plasma from N. rileyi infected H. armigera larvae suppressed the spreading ability of hemocytes from naïve larvae. We infer that N. rileyi suppresses the cellular immune response of its host, possibly by secreting exogenous, cytotoxic compounds into the host's hemolymph. © 2017 Wiley Periodicals, Inc.

Analysis of the Genome of the Sexually Transmitted Insect Virus Helicoverpa zea Nudivirus 2

PubMed Central

Burand, John P.; Kim, Woojin; Afonso, Claudio L.; Tulman, Edan R.; Kutish, Gerald F.; Lu, Zhiqiang; Rock, Daniel L.

2012-01-01

The sexually transmitted insect virus Helicoverpa zea nudivirus 2 (HzNV-2) was determined to have a circular double-stranded DNA genome of 231,621 bp coding for an estimated 113 open reading frames (ORFs). HzNV-2 is most closely related to the nudiviruses, a sister group of the insect baculoviruses. Several putative ORFs that share homology with the baculovirus core genes were identified in the viral genome. However, HzNV-2 lacks several key genetic features of baculoviruses including the late transcriptional regulation factor, LEF-1 and the palindromic hrs, which serve as origins of replication. The HzNV-2 genome was found to code for three ORFs that had significant sequence homology to cellular genes which are not generally found in viral genomes. These included a presumed juvenile hormone esterase gene, a gene coding for a putative zinc-dependent matrix metalloprotease, and a major facilitator superfamily protein gene; all of which are believed to play a role in the cellular proliferation and the tissue hypertrophy observed in the malformation of reproductive organs observed in HzNV-2 infected corn earworm moths, Helicoverpa zea. PMID:22355451

Analysis of the genome of the sexually transmitted insect virus Helicoverpa zea nudivirus 2.

PubMed

Burand, John P; Kim, Woojin; Afonso, Claudio L; Tulman, Edan R; Kutish, Gerald F; Lu, Zhiqiang; Rock, Daniel L

2012-01-01

The sexually transmitted insect virus Helicoverpa zea nudivirus 2 (HzNV-2) was determined to have a circular double-stranded DNA genome of 231,621 bp coding for an estimated 113 open reading frames (ORFs). HzNV-2 is most closely related to the nudiviruses, a sister group of the insect baculoviruses. Several putative ORFs that share homology with the baculovirus core genes were identified in the viral genome. However, HzNV-2 lacks several key genetic features of baculoviruses including the late transcriptional regulation factor, LEF-1 and the palindromic hrs, which serve as origins of replication. The HzNV-2 genome was found to code for three ORFs that had significant sequence homology to cellular genes which are not generally found in viral genomes. These included a presumed juvenile hormone esterase gene, a gene coding for a putative zinc-dependent matrix metalloprotease, and a major facilitator superfamily protein gene; all of which are believed to play a role in the cellular proliferation and the tissue hypertrophy observed in the malformation of reproductive organs observed in HzNV-2 infected corn earworm moths, Helicoverpa zea.

Food deprivation reduces and leptin increases the amplitude of an active sensory and communication signal in a weakly electric fish.

PubMed

Sinnett, Philip M; Markham, Michael R

2015-05-01

Energetic demands of social communication signals can constrain signal duration, repetition, and magnitude. The metabolic costs of communication signals are further magnified when they are coupled to active sensory systems that require constant signal generation. Under such circumstances, metabolic stress incurs additional risk because energy shortfalls could degrade sensory system performance as well as the social functions of the communication signal. The weakly electric fish Eigenmannia virescens generates electric organ discharges (EODs) that serve as both active sensory and communication signals. These EODs are maintained at steady frequencies of 200-600Hz throughout the lifespan, and thus represent a substantial metabolic investment. We investigated the effects of metabolic stress (food deprivation) on EOD amplitude (EODa) and EOD frequency (EODf) in E. virescens and found that only EODa decreases during food deprivation and recovers after restoration of feeding. Cortisol did not alter EODa under any conditions, and plasma cortisol levels were not changed by food deprivation. Both melanocortin hormones and social challenges caused transient EODa increases in both food-deprived and well-fed fish. Intramuscular injections of leptin increased EODa in food-deprived fish but not well-fed fish, identifying leptin as a novel regulator of EODa and suggesting that leptin mediates EODa responses to metabolic stress. The sensitivity of EODa to dietary energy availability likely arises because of the extreme energetic costs of EOD production in E. virescens and also could reflect reproductive strategies of iteroparous species that reduce social signaling and reproduction during periods of stress to later resume reproductive efforts when conditions improve. Copyright © 2015. Published by Elsevier Inc.

The genetic architecture of a complex ecological trait: host plant use in the specialist moth, HELIOTHIS SUBFLEXA

USDA-ARS?s Scientific Manuscript database

The study of the genetic basis of ecological adaptation remains in its infancy, and most studies have focused on phenotypically simple traits. Host plant use by herbivorous insects is phenotypically complex. While research has illuminated the evolutionary determinants of host use, knowledge of its...

Heliothis zea nudivirus 1 gene hhi1 induces apoptosis which is blocked by the Hz-iap2 gene and a noncoding gene, pag1.

PubMed

Wu, Yueh-Lung; Wu, Carol P; Liu, Catherine Y Y; Lee, Song-Tay; Lee, Hsiao-Ping; Chao, Yu-Chan

2011-07-01

Heliothis zea nudivirus 1 (HzNV-1 or Hz-1 virus), previously regarded as a nonoccluded baculovirus, recently has been placed in the Nudivirus genus. This virus generates HzNV-1 HindIII-I 1 (hhi1) and many other transcripts during productive viral infection; during latent viral infection, however, persistency-associated gene 1 (pag1) is the only gene expressed. In this report, we used transient expression assays to show that hhi1 can trigger strong apoptosis in transfected cells, which can be blocked, at least partially, by the inhibitor of apoptosis genes Autographa californica iap2 (Ac-iap2) and H. zea iap2 (Hz-iap2). In addition to these two genes, unexpectedly, pag1, which encodes a noncoding RNA with no detectable protein product, was found to efficiently suppress hhi1-induced apoptosis. The assay of pro-Sf-caspase-1 processing by hhi1 transfection did not detect the small P12 subunit at any of the time intervals tested, suggesting that hhi1 of HzNV-1 induces apoptosis through alternative caspase pathways.

Suitability Measurement and Analysis for Fort Bliss Naval Air Facility OLS. Opportune Landing Site Program

DTIC Science & Technology

2008-09-01

bushes on the RAS. ERDC/CRREL TR-08-16 71 d. Delphinium virescens.4 e. Nolina microcarpa .5 f. Lygodesmia exigua.6 Figure 27 (cont’d...4 There are a few of these plants along the RAS. 5 There are a few nolinas on the RAS

Recognizing and managing sapstreak disease of sugar maple

Treesearch

David R. Houston; David R. Houston

1993-01-01

Sapstreak disease, a potentially serious problem of sugarbushes and forest stands, occurs when the causal fungus, Ceratocystis virescens, invades the sapwood of roots and bases of stems through wounds inflicted during logging, saphauling, or other activities. Describes how to recognize the disease, the factors that affect its occurrence and development, and management...

Parents or predators: Examining intraseasonal variation in nest survival for migratory passerine

Treesearch

Robin Hirsch-Jacobson; W. Andrew Cox; Emily E. Tewes; Frank R., III Thompson; John Faaborg

2012-01-01

For birds, risk of nest predation can vary within a breeding season, but few data exist that explain why such variation occurs. We investigated intraseasonal variation of nest survival of the Acadian Flycatcher (Empidonax virescens) in Midwestern forests and tested whether four of the adults' reproductive strategies (clutch size, nest...

Practical uses for ecdysteroids in mammals including humans: an update

PubMed Central

Lafont, R.; Dinan, L.

2003-01-01

Ecdysteroids are widely used as inducers for gene-switch systems based on insect ecdysteroid receptors and genes of interest placed under the control of ecdysteroid-response elements. We review here these systems, which are currently mainly used in vitro with cultured cells in order to analyse the role of a wide array of genes, but which are expected to represent the basis for future gene therapy strategies. Such developments raise several questions, which are addressed in detail. First, the metabolic fate of ecdysteroids in mammals, including humans, is only poorly known, and the rapid catabolism of ecdysteroids may impede their use as in vivo inducers. A second set of questions arose in fact much earlier with the pioneering “heterophylic” studies of Burdette in the early sixties on the pharmacological effects of ecdysteroids on mammals. These and subsequent studies showed a wide range of effects, most of them being beneficial for the organism (e.g. hypoglycaemic, hypocholesterolaemic, anabolic). These effects are reviewed and critically analysed, and some hypotheses are proposed to explain the putative mechanisms involved. All of these pharmacological effects have led to the development of a wide array of ecdysteroid-containing preparations, which are primarily used for their anabolic and/or “adaptogenic” properties on humans (or horses or dogs). In the same way, increasing numbers of patents have been deposited concerning various beneficial effects of ecdysteroids in many medical or cosmetic domains, which make ecdysteroids very attractive candidates for several practical uses. It may be questioned whether all these pharmacological actions are compatible with the development of ecdysteroid-inducible gene switches for gene therapy, and also if ecdysteroids should be classified among doping substances. Abbreviation: 20E 20-hydroxyecdysone 2d20E 2-deoxy-20-hydroxyecdysone 2dE 2-deoxyecdysone BAH bisacylhydrazine BmEcR Bombyx mori EcR CfEcR Choristoneura fumiferana EcR CfUSP Choristoneura fumiferana USP CHO Chinese hamster ovary CMV cytomegalovirus DBD DNA-binding domain DmEcR Drosophila melanogaster EcR AbbE ecdysone EcR ecdysteroid receptor EcRE ecdysteroid response element EHT effective half-time ERE oestrogen response element GR glucocorticoid receptor GRE glucocorticoid response element HEK human embryonic kidney HvEcR Heliothis virescens EcR LBD ligand binding domain murA muristerone A PKA protein kinase A polB polypodine B ponA ponasterone A PPAR peroxisome proliferator-activated receptor RAR retinoic acid receptor RXR retinoid X receptor TR thyroid receptor USP ultraspiracle VDR vitamin D receptor VEGF vascular endothelial growth factor PMID:15844229

Fish stomach contents in benthic macroinvertebrate assemblage assessments.

PubMed

Tupinambás, T H; Pompeu, P S; Gandini, C V; Hughes, R M; Callisto, M

2015-01-01

The choice of sampling gears to assess benthic macroinvertebrate communities depends on environmental characteristics, study objectives, and cost effectiveness. Because of the high foraging capacity and diverse habitats and behaviors of benthophagous fishes, their stomach contents may offer a useful sampling tool in studies of benthic macroinvertebrates, especially in large, deep, fast rivers that are difficult to sample with traditional sediment sampling gear. Our objective was to compare the benthic macroinvertebrate communities sampled from sediments with those sampled from fish stomachs. We collected benthic macroinvertebrates and fish from three different habitat types (backwater, beach, riffle) in the wet season, drying season, and dry season along a single reach of the Grande River (Paraná River Basin, southeast Brazil). We sampled sediments through use of a Petersen dredge (total of 216 grabs) and used gill nets to sample fish (total of 36 samples). We analyzed the stomach contents of three commonly occurring benthophagous fish species (Eigenmannia virescens, Iheringichthys labrosus, Leporinus amblyrhynchus). Chironomids dominated in both sampling methods. Macroinvertebrate taxonomic composition and abundances from fish stomachs differed from those from sediment samples, but less so from riffles than from backwater and beach habitats. Macroinvertebrate taxa from E. virescens stomachs were more strongly correlated with sediment samples from all three habitats than were those from the other two species. The species accumulation curves and higher mean dispersion values, compared with with sediment samples suggest that E. virescens is more efficient than sediment samples and the other fish studied at collecting benthic taxa. We conclude that by analyzing the stomach contents of benthophagous fishes it is possible to assess important characteristics of benthic communities (dispersion, taxonomic composition and diversity). This is especially true for studies that only sample fish assemblages to evaluate aquatic ecosystem impacts. Therefore, this approach can be useful to amplify assessments of human impacts, and to incorporate additional bioindicators.

Significance of Penicillium ochrochloron chitinase as a biocontrol agent against pest Helicoverpa armigera.

PubMed

Patil, Nilambari S; Jadhav, Jyoti P

2015-06-01

Penicillium ochrochloron chitinase purified by DEAE-cellulose ion exchange chromatography was evaluated for its antifeedant and growth inhibitory activities against Helicoverpa armigera at different concentrations of 2000, 1000, 500, 250 and 100 U mL(-1). It reduced the successful pupation and increased larval and pupal mortality, adult emergence in a dosage-dependent manner when applied topically. The highest mortalities were recorded for groups treated with 2000 U mL(-1) chitinase activity. The studies showed P.ochrochloron chitinase can affect the growth of H.armigera larvae. Since this insect pest species has developed resistance and resurgence to chemical insecticides, only alternate is the usage of enzyme-based pesticide formulations as an environmentally friendly pest management tool. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sapstreak disease of sugar maple: development over time and space

Treesearch

David R. Houston

1994-01-01

Sapstreak disease is a potentially serious problem of sugarbushes and forest stands. It is caused by the fungus Ceratocystis virescens, which invades sapwood of roots and bases of stems through wounds created during logging, saphauling, or other activities. This publication describes the results of observations and experiments to learn more about the patterns of...

Landscape forest cover and edge effects on songbird nest predation vary by nest predator

Treesearch

W. Andrew Cox; Frank R. III Thompson; John Faaborg

2012-01-01

Rates of nest predation for birds vary between and within species across multiple spatial scales, but we have a poor understanding of which predators drive such patterns. We video-monitored nests and identified predators at 120 nests of the Acadian Flycatcher (Empidonax virescens) and the Indigo Bunting (Passerina cyanea) at eight...

α-Amanitin-Resistant Viral RNA Synthesis in Nuclei Isolated from Nuclear Polyhedrosis Virus-Infected Heliothis zea Larvae and Spodoptera frugiperda Cells

PubMed Central

Grula, Marjori A.; Buller, Patricia L.; Weaver, Robert F.

1981-01-01

[3H]RNA was synthesized in nuclei isolated at various times postinfection from the fat bodies of Heliothis zea larvae infected with H. zea nuclear polyhedrosis virus and from cultured Spodoptera frugiperda cells infected with Autographa californica nuclear polyhedrosis virus. To detect virus-specific RNA synthesis, the [3H]RNA was hybridized to denatured viral DNA immobilized on nitrocellulose filters. Nuclear polyhedrosis virus-specific RNA synthesis in the infected nuclei isolated from H. zea larval fat bodies and S. frugiperda cells was only inhibited 20 to 25% by concentrations of α-amanitin sufficient to inhibit the host RNA polymerase II. In addition, a productive nuclear polyhedrosis virus infection was obtained in S. frugiperda cells grown in the presence of an α-amanitin concentration that inhibited 90% of the cellular RNA polymerase II activity. The cellular RNA polymerase II enzyme remained sensitive to α-amanitin during infection, and there was no evidence that a virus-coded, α-amanitin-resistant enzyme was synthesized after the onset of infection. The data suggest that the bulk of nuclear polyhedrosis virus-specific RNA synthesis in isolated nuclei is transcribed by an enzyme other than the host RNA polymerase II. PMID:16789208

Effects of Helicoverpa armigera (Noctuidae, Lepidoptera) host stages on some developmental parameters of the uniparental endoparasitoid Meteorus pulchricornis (Braconidae, Hymenoptera).

PubMed

Liu, Ya-Hui; Li, Bao-Ping

2008-04-01

A single choice test was performed to examine developmental strategies in the uniparental endoparasitoid Meteorus pulchricornis and its host, the cotton bollworm Helicoverpa armigera. The results support the dome-shaped model in which the fitness functions are 'dome-shaped' relative to size (and age) of host at parasitism. Older and, hence, larger host larvae were simply not better hosts for the developing parasitoids. Although parasitoid size (measured as cocoon weight and adult hind tibia length) was positively correlated with host instars at parasitism, parasitoids developing in larger hosts (L5 and L6) suffered much higher mortality than conspecifics developing in smaller hosts (L2-L4). Furthermore, egg-to-adult development time in M. pulchricornis was significantly longer in older host larvae (L4-L6) than in the younger. Performance of M. pulchricornis, as indicated by fitness-related traits, strongly suggests that the L3 host is the most suitable for survival, growth and development of the parasitoid, followed by both L2 and L4 hosts; whereas, L1, L5 and L6 are the least favourable hosts. The oviposition tendency of M. pulchricornis, represented by parasitism level, was not perfectly consistent with the performance of the offspring; L2-L4 hosts, although with the same parasitism level, had offspring parasitoids with differences in fitness-related performance. Larval development in Helicoverpa armigera was usually suspended, but occasionally advanced, in the final instar.

Species and temporal factors affect predator-specific rates of nest predation for forest songbirds in the midwest

Treesearch

W. Andrew Cox; Frank R. III Thompson; John Faaborg

2012-01-01

Knowledge of the relative contributions of predator species to overall rates of nest predation can improve our understanding of why predation risk varies, but the identity of predators is seldom known. We used video technology to identify nest predators of the tree-nesting Acadian Flycatcher (Empidonax virescens) and the shrub-nesting Indigo Bunting...

Peripheral genetic structure of Helicoverpa zea indicates asymmetrical panmixia

USDA-ARS?s Scientific Manuscript database

Seasonal climatic shifts create peripheral habitats that alternate between habitable and uninhabitable for migratory species. Such dynamic peripheral habitats are potential sites where migratory species could evolve high genetic diversity resulting from convergence of immigrants from multiple region...

Distribution of /sup 32/P in laboratory colonies of Solenopsis invicta (Hymenoptera: Formicidae) after feeding on labeled Heliothis zeal (Lepidoptera: Noctuidae) eggs: an explanation of discrepancies encountered in field predation experiments

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

Nuessly, G.S.; Sterling, W.L.

1986-12-01

Factors responsible for low recovery rates of radioactive Solenopsis invicta Buren following placement of /sup 32/P-labeled Heliothis zea (Boddie) eggs on cotton in field predation tests were investigated using laboratory colonies of the ants. S. invicta workers became radioactive while handling labeled eggs by rupturing the egg chorion or by picking up labeled substances present on the surface of eggs. Foragers that removed the eggs from the plants picked up significantly more of the label than did workers that were sampled from the colonies between 12 and 72 h after egg introduction. Percentage of workers that became labeled over timemore » was much lower with the solid live food than in other studies that used powdered food sources. Problems in finding labeled ants in the field may have been associated with low mean levels of /sup 32/P per ant, together with difficulty in locating and isolating labeled ants from the population. Results indicate that egg predation rates estimated from counts per minute per predator have high variability, and suggest fairly large errors in estimates of eggs consumed per ant. Use of recovery rates of labeled predators to improve estimation of predation rates is discussed.« less

Encoding of social signals in all three electrosensory pathways of Eigenmannia virescens.

PubMed

Stöckl, Anna; Sinz, Fabian; Benda, Jan; Grewe, Jan

2014-11-01

Extracting complementary features in parallel pathways is a widely used strategy for a robust representation of sensory signals. Weakly electric fish offer the rare opportunity to study complementary encoding of social signals in all of its electrosensory pathways. Electrosensory information is conveyed in three parallel pathways: two receptor types of the tuberous (active) system and one receptor type of the ampullary (passive) system. Modulations of the fish's own electric field are sensed by these receptors and used in navigation, prey detection, and communication. We studied the neuronal representation of electric communication signals (called chirps) in the ampullary and the two tuberous pathways of Eigenmannia virescens. We first characterized different kinds of chirps observed in behavioral experiments. Since Eigenmannia chirps simultaneously drive all three types of receptors, we studied their responses in in vivo electrophysiological recordings. Our results demonstrate that different electroreceptor types encode different aspects of the stimuli and each appears best suited to convey information about a certain chirp type. A decoding analysis of single neurons and small populations shows that this specialization leads to a complementary representation of information in the tuberous and ampullary receptors. This suggests that a potential readout mechanism should combine information provided by the parallel processing streams to improve chirp detectability. Copyright © 2014 the American Physiological Society.

Differential activity of multiple saponins against omnivorous insects with varying feeding preferences

USDA-ARS?s Scientific Manuscript database

A variety of saponin glycosides and aglycones from seven different plant families (Aquifoliaceae, Asparagaceae, Caryophyllaceae, Dioscoreaceae, Leguminosae, Rosaceae, Sapindaceae) were tested against the corn earworm, Helicoverpa zea, and the fall armyworm, Spodoptera frugiperda. The corn earworm fe...

Impact of transgenic sweet corn silks to two noctuid pests

USDA-ARS?s Scientific Manuscript database

Eight Bacillus thuringiensis (Bt) transgenic sweet corn hybrids were evaluated (with two controls) for their efficacy against two ear-feeding insects; the corn earworm [Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)], and the fall armyworm (Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuid...

Site-directed mutagenesis and PBAN activation of the Helicoverpa zea PBAN-receptor

USDA-ARS?s Scientific Manuscript database

Insect neuropeptides are produced in the central or peripheral nerve tissues, and released to regulate various physiological and behavioral actions during development and reproduction. Pheromone biosynthesis-activating neuropeptide (PBAN)/Pyrokinin is a major neuropeptide family characterized with a...

A Multiplex Real-Time PCR Assay to Diagnose and Separate Helicoverpa armigera and H. zea (Lepidoptera: Noctuidae) in the New World

PubMed Central

Gilligan, Todd M.; Tembrock, Luke R.; Farris, Roxanne E.; Barr, Norman B.; van der Straten, Marja J.; van de Vossenberg, Bart T. L. H.; Metz-Verschure, Eveline

2015-01-01

The Old World bollworm, Helicoverpa armigera (Hübner), and the corn earworm, H. zea (Boddie), are two of the most important agricultural pests in the world. Diagnosing these two species is difficult—adults can only be separated with a complex dissection, and larvae cannot be identified to species using morphology, necessitating the use of geographic origin for identification in most instances. With the discovery of H. armigera in the New World, identification of immature Helicoverpa based on origin is no longer possible because H. zea also occurs in all of the geographic regions where H. armigera has been discovered. DNA barcoding and restriction fragment length polymorphism (RFLP) analyses have been reported in publications to distinguish these species, but these methods both require post-PCR processing (i.e., DNA sequencing or restriction digestion) to complete. We report the first real-time PCR assay to distinguish these pests based on two hydrolysis probes that bind to a segment of the internal transcribed spacer region 2 (ITS2) amplified using a single primer pair. One probe targets H. armigera, the second probe targets H. zea, and a third probe that targets a conserved segment of 18S rDNA is used as a control of DNA quality. The assay can be completed in 50 minutes when using isolated DNA and is successfully tested on larvae intercepted at ports of entry and adults captured during domestic surveys. We demonstrate that the assay can be run in triplex with no negative effects on sensitivity, can be run using alternative real-time PCR reagents and instruments, and does not cross react with other New World Heliothinae. PMID:26558366

A Multiplex Real-Time PCR Assay to Diagnose and Separate Helicoverpa armigera and H. zea (Lepidoptera: Noctuidae) in the New World.

PubMed

Gilligan, Todd M; Tembrock, Luke R; Farris, Roxanne E; Barr, Norman B; van der Straten, Marja J; van de Vossenberg, Bart T L H; Metz-Verschure, Eveline

2015-01-01

The Old World bollworm, Helicoverpa armigera (Hübner), and the corn earworm, H. zea (Boddie), are two of the most important agricultural pests in the world. Diagnosing these two species is difficult-adults can only be separated with a complex dissection, and larvae cannot be identified to species using morphology, necessitating the use of geographic origin for identification in most instances. With the discovery of H. armigera in the New World, identification of immature Helicoverpa based on origin is no longer possible because H. zea also occurs in all of the geographic regions where H. armigera has been discovered. DNA barcoding and restriction fragment length polymorphism (RFLP) analyses have been reported in publications to distinguish these species, but these methods both require post-PCR processing (i.e., DNA sequencing or restriction digestion) to complete. We report the first real-time PCR assay to distinguish these pests based on two hydrolysis probes that bind to a segment of the internal transcribed spacer region 2 (ITS2) amplified using a single primer pair. One probe targets H. armigera, the second probe targets H. zea, and a third probe that targets a conserved segment of 18S rDNA is used as a control of DNA quality. The assay can be completed in 50 minutes when using isolated DNA and is successfully tested on larvae intercepted at ports of entry and adults captured during domestic surveys. We demonstrate that the assay can be run in triplex with no negative effects on sensitivity, can be run using alternative real-time PCR reagents and instruments, and does not cross react with other New World Heliothinae.

Effects of Soil Salinity on the Expression of Bt Toxin (Cry1Ac) and the Control Efficiency of Helicoverpa armigera in Field-Grown Transgenic Bt Cotton.

PubMed

Luo, Jun-Yu; Zhang, Shuai; Peng, Jun; Zhu, Xiang-Zhen; Lv, Li-Min; Wang, Chun-Yi; Li, Chun-Hua; Zhou, Zhi-Guo; Cui, Jin-Jie

2017-01-01

An increasing area of transgenic Bacillus thuringiensis (Bt) cotton is being planted in saline-alkaline soil in China. The Bt protein level in transgenic cotton plants and its control efficiency can be affected by abiotic stress, including high temperature, water deficiency and other factors. However, how soil salinity affects the expression of Bt protein, thus influencing the control efficiency of Bt cotton against the cotton bollworm (CBW) Helicoverpa armigera (Hübner) in the field, is poorly understood. Our objective in the present study was to investigate the effects of soil salinity on the expression of Bt toxin (Cry1Ac) and the control efficiency of Helicoverpa armigera in field-grown transgenic Bt cotton using three natural saline levels (1.15 dS m-1 [low soil-salinity], 6.00 dS m-1 [medium soil-salinity] and 11.46 dS m-1 [high soil-salinity]). We found that the Bt protein content in the transgenic Bt cotton leaves and the insecticidal activity of Bt cotton against CBW decreased with the increasing soil salinity in laboratory experiments during the growing season. The Bt protein content of Bt cotton leaves in the laboratory were negatively correlated with the salinity level. The CBW populations were highest on the Bt cotton grown in medium-salinity soil instead of the high-salinity soil in field conditions. A possible mechanism may be that the relatively high-salinity soil changed the plant nutritional quality or other plant defensive traits. The results from this study may help to identify more appropriate practices to control CBW in Bt cotton fields with different soil salinity levels.

Effects of Soil Salinity on the Expression of Bt Toxin (Cry1Ac) and the Control Efficiency of Helicoverpa armigera in Field-Grown Transgenic Bt Cotton

PubMed Central

Luo, Jun-Yu; Zhang, Shuai; Peng, Jun; Zhu, Xiang-Zhen; Lv, Li-Min; Wang, Chun-Yi; Li, Chun-Hua; Zhou, Zhi-Guo; Cui, Jin-Jie

2017-01-01

An increasing area of transgenic Bacillus thuringiensis (Bt) cotton is being planted in saline-alkaline soil in China. The Bt protein level in transgenic cotton plants and its control efficiency can be affected by abiotic stress, including high temperature, water deficiency and other factors. However, how soil salinity affects the expression of Bt protein, thus influencing the control efficiency of Bt cotton against the cotton bollworm (CBW) Helicoverpa armigera (Hübner) in the field, is poorly understood. Our objective in the present study was to investigate the effects of soil salinity on the expression of Bt toxin (Cry1Ac) and the control efficiency of Helicoverpa armigera in field-grown transgenic Bt cotton using three natural saline levels (1.15 dS m-1 [low soil-salinity], 6.00 dS m-1 [medium soil-salinity] and 11.46 dS m-1 [high soil-salinity]). We found that the Bt protein content in the transgenic Bt cotton leaves and the insecticidal activity of Bt cotton against CBW decreased with the increasing soil salinity in laboratory experiments during the growing season. The Bt protein content of Bt cotton leaves in the laboratory were negatively correlated with the salinity level. The CBW populations were highest on the Bt cotton grown in medium-salinity soil instead of the high-salinity soil in field conditions. A possible mechanism may be that the relatively high-salinity soil changed the plant nutritional quality or other plant defensive traits. The results from this study may help to identify more appropriate practices to control CBW in Bt cotton fields with different soil salinity levels. PMID:28099508

Lepidopterous pests of tomato: biology, ecology and management

USDA-ARS?s Scientific Manuscript database

Tomato, Solanum lycopersicum L., serves as a host to a diverse array of arthropod pests including several species of Lepidoptera. Some of these pests are more problematic and more widespread than others. This book chapter concerns nine of the particularly problematic lepidopterans (Helicoverpa armig...

Influence of (+)- to (-)-gossypol ratio on Helicoverpa zea larval development

USDA-ARS?s Scientific Manuscript database

Gossypol enantiomer ratios vary considerably among Gossypium species and between different plant tissues. Breeding efforts have focused on the development of germplasm lines with a high (+)- to (-)-gossypol ratio due to the toxicity (-)-gossypol to non-ruminant animals. Interestingly, a previous s...

Feeding deterrent and growth inhibitory activities of PONNEEM, a newly developed phytopesticidal formulation against Helicoverpa armigera (Hubner)

PubMed Central

Packiam, Soosaimanickam Maria; Baskar, Kathirvelu; Ignacimuthu, Savarimuthu

2014-01-01

Objective To assess the feeding deterrent, growth inhibitory and egg hatchability effects of PONNEEM on Helicoverpa armigera (H. armigera). Methods Five oil formulations were prepared at different ratios to assess the feeding deterrent, growth inhibitory and egg hatchability effects on H. armigera. Results Invariably all the newly formulated phytopesticidal oil formulations showed the feeding deterrent and growth inhibitory activities against H. armigera. The maximum feeding deterrent activity of 88.44% was observed at 15 µL/L concentration of PONNEEM followed by formulation A (74.54%). PONNEEM was found to be effective in growth inhibitory activities and egg hatchability at 10 µL/L concentration. It exhibited statistically significant feeding deterrent activity and growth inhibitory activity compared with all the other treatments. Conclusions PONNEEM was found to be effective phytopesticidal formulation to control the larval stage of H. armigera. This is the first report for the feeding deterrent activity of PONNEEM against H. armigera. This newly formulated phytopesticide was patented in India. PMID:25183105

Cannibalism Affects Core Metabolic Processes in Helicoverpa armigera Larvae-A 2D NMR Metabolomics Study.

PubMed

Vergara, Fredd; Shino, Amiu; Kikuchi, Jun

2016-09-02

Cannibalism is known in many insect species, yet its impact on insect metabolism has not been investigated in detail. This study assessed the effects of cannibalism on the metabolism of fourth-instar larvae of the non-predatory insect Helicoverpa armigera (Lepidotera: Noctuidea). Two groups of larvae were analyzed: one group fed with fourth-instar larvae of H. armigera (cannibal), the other group fed with an artificial plant diet. Water-soluble small organic compounds present in the larvae were analyzed using two-dimensional nuclear magnetic resonance (NMR) and principal component analysis (PCA). Cannibalism negatively affected larval growth. PCA of NMR spectra showed that the metabolic profiles of cannibal and herbivore larvae were statistically different with monomeric sugars, fatty acid- and amino acid-related metabolites as the most variable compounds. Quantitation of ¹H-(13)C HSQC (Heteronuclear Single Quantum Coherence) signals revealed that the concentrations of glucose, glucono-1,5-lactone, glycerol phosphate, glutamine, glycine, leucine, isoleucine, lysine, ornithine, proline, threonine and valine were higher in the herbivore larvae.

Innate preference and learning of colour in the male cotton bollworm moth, Helicoverpa armigera.

PubMed

Satoh, Aya; Kinoshita, Michiyo; Arikawa, Kentaro

2016-12-15

We investigated colour discrimination and learning in adult males of the nocturnal cotton bollworm moth, Helicoverpa armigera, under a dim light condition. The naive moths preferred blue and discriminated the innately preferred blue from several shades of grey, indicating that the moths have colour vision. After being trained for 2 days to take nectar at a yellow disc, an innately non-preferred colour, moths learned to select yellow over blue. The choice distribution between yellow and blue changed significantly from that of naive moths. However, the dual-choice distribution of the trained moths was not significantly biased to yellow: the preference for blue is robust. We also tried to train moths to grey, which was not successful. The limited ability to learn colours suggests that H armigera may not strongly rely on colours when searching for flowers in the field, although they have the basic property of colour vision. © 2016. Published by The Company of Biologists Ltd.

Inhibition of melanization by serpin-5 and serpin-9 promotes baculovirus infection in cotton bollworm Helicoverpa armigera

PubMed Central

Wang, Manli; Wang, Xi; Yin, Mengyi; Wang, Qianran; Hu, Zhihong

2017-01-01

Melanization, an important insect defense mechanism, is mediated by clip-domain serine protease (cSP) cascades and is regulated by serpins. Here we show that proteolytic activation of prophenoloxidase (PPO) and PO-catalyzed melanization kill the baculovirus in vitro. Our quantitative proteomics and biochemical experiments revealed that baculovirus infection of the cotton bollworm, Helicoverpa armigera, reduced levels of most cascade members in the host hemolymph and PO activity. By contrast, serpin-9 and serpin-5 were sequentially upregulated after the viral infection. The H. armigera serpin-5 and serpin-9 regulate melanization by directly inhibiting their target proteases cSP4 and cSP6, respectively and cSP6 activates PPO purified from hemolymph. Furthermore, serpin-5/9-depleted insects exhibited high PO activities and showed resistance to baculovirus infection. Together, our results characterize a part of the melanization cascade in H. armigera, and suggest that natural insect virus baculovirus has evolved a distinct strategy to suppress the host immune system. PMID:28953952

A transferrin gene associated with development and 2-tridecanone tolerance in Helicoverpa armigera

PubMed Central

Zhang, L; Shang, Q; Lu, Y; Zhao, Q; Gao, X

2015-01-01

The full-length cDNA (2320 bp) encoding a putative iron-binding transferrin protein from Helicoverpa armigera was cloned and named HaTrf. The putative HaTrf sequence included 670 amino acids with a molecular mass of approximately 76 kDa. Quantitative PCR results demonstrated that the transcriptional level of HaTrf was significantly higher in the sixth instar and pupa stages as compared with other developmental stages. HaTrf transcripts were more abundant in fat bodies and in the epidermis than in malpighian tubules. Compared with the control, the expression of HaTrf increased dramatically 24 h after treatment with 2-tridecanone. Apparent growth inhibition with a dramatic body weight decrease was observed in larvae fed with HaTrf double-stranded RNA (dsRNA), as compared with those fed with green fluorescent protein dsRNA. RNA interference of HaTrf also significantly increased the susceptibility of larvae to 2-tridecanone. These results indicate the possible involvement of HaTrf in tolerance to plant secondary chemicals. PMID:25430818

Interaction of plant cell signaling molecules, salicylic acid and jasmonic acid, with the mitochondria of Helicoverpa armigera.

PubMed

Akbar, S M D; Sharma, H C; Jayalakshmi, S K; Sreeramulu, K

2012-02-01

The cotton bollworm, Helicoverpa armigera is a polyphagous pest in Asia, Africa, and the Mediterranean Europe. Salicylic acid (SA) and jasmonic acid (JA) are the cell signaling molecules produced in response to insect attack in plants. The effect of these signaling molecules was investigated on the oxidative phosphorylation and oxidative stress of H. armigera. SA significantly inhibited the state III and state IV respiration, respiratory control index (RCI), respiratory complexes I and II, induced mitochondrial swelling, and cytochrome c release in vitro. Under in vivo conditions, SA induced state IV respiration as well as oxidative stress in time- and dose-dependent manner, and also inhibited the larval growth. In contrast, JA did not affect the mitochondrial respiration and oxidative stress. SA affected the growth and development of H. armigera, in addition to its function as signaling molecules involved in both local defense reactions at feeding sites and the induction of systemic acquired resistance in plants.

Spatio-temporal variation in Helicoverpa egg parasitism by Trichogramma in a tropical Bt-transgenic cotton landscape

USDA-ARS?s Scientific Manuscript database

Understanding the spatio-temporal dynamics of insects in agroecosystems is crucial when developing effective management strategies that emphasise biological control of pests. Wild populations of Trichogramma Westwood egg parasitoids are utilised for biological suppression of the potentially resistan...

Effect of gossypolone on the growth and development of helicoverpa zea

USDA-ARS?s Scientific Manuscript database

The pigment glands of the cotton plant (Gossypium) produce terpenoid aldehydes that protect the plant from herbivorous insects. Of these terpenoids, the most extensively studied is gossypol. Gossypolone, a compound closely related to gossypol, has been reported in these pigment glands but its activ...

Induction of glutathione S-Transferase in Helicoverpa zea fed cashew flour.

USDA-ARS?s Scientific Manuscript database

H. zea and other insects have evolved strategies to counteract the plant protective proteins and defensive compounds they may encounter during feeding. We sought to take advantage of this phenomenon by identifying proteins upregulated in H. zea in response to the inclusion of cashew nut flour in th...

Supplemental control with diamides for Heliothines1 in Bt Cotton

USDA-ARS?s Scientific Manuscript database

Supplemental control of bollworm, Helicoverpa zea (Boddie), in Bt cotton with diamides is becoming more frequent, but there is little information on the net returns to growers. Seven locations were established across the MS Delta cropping region between 2014 and 2015 to examine the value of spraying...

CRISPR/Cas9 mediated high efficiency knockout of the eye color gene vermillion in Helicoverpa zea (Boddie)

USDA-ARS?s Scientific Manuscript database

Among various genome editing tools available for functional genomic studies, reagents based on clustered regularly interspersed palindromic repeats (CRISPR) have gained popularity due to ease and versatility. CRISPR reagents consists of ribonucleoprotein (RNP) complexes formed by combining guide RNA...

Searching responses of a hunting spider to cues associated with lepidopteran eggs

USDA-ARS?s Scientific Manuscript database

Cheiracanthium inclusum (Hentz), a cursorial spider, has been frequently observed feeding on the eggs of Helicoverpa zea (Boddie), an important cotton pest. This study investigated whether compounds present in H. zea scales and egg residues could act as kairomones and be used by C. inclusum in its ...

Effect of abamectin on feeding response, mortality, and reproduction of adult bollworm (Lepidoptera: Noctuidae)

USDA-ARS?s Scientific Manuscript database

Newly eclosed adult bollworm, Helicoverpa zea (Boddie) feeds on carbohydrate sources from plants and other exudates prior to dispersal and reproduction. The objective of this study was to determine whether or not this nocturnal behavior could be exploited for pest management by presenting the insect...

Effect of eastern gamagrass on fall armyworm and corn earworm development

USDA-ARS?s Scientific Manuscript database

The fall armyworm, Spodoptera frugiperda (J.E. Smith) and the corn earworm, Helicoverpa zea (Boddie) are two important corn pests in the southern U.S. states. Effect of the leaves from the corn relative, the Eastern gamagrass (Tripsacum dactyloides L.) on fall armyworm and corn earworm development ...

Efficacy of silk channel injections with insecticides for management of Lepidopteran pests of sweet corn

USDA-ARS?s Scientific Manuscript database

The primary Lepidopteran pests of sweet corn in Georgia are the corn earworm, Helicoverpa zea (Boddie), and the fall armyworm, Spodoptera frugiperda (J.E. Smith). Control of these pests typically requires multiple insecticide applications from first silking until harvest, with commercial growers fre...

Baculovirus replication induces the expression of heat shock proteins in vivo and in vitro

USDA-ARS?s Scientific Manuscript database

A recent handful of studies have linked baculovirus infection with the induction of heat shock proteins, a highly conserved family of cytoprotective proteins. Here, we demonstrate baculovirus-stimulated upregulation of hsp70 transcription in the natural host, Helicoverpa zea. Larvae lethally infec...

Integration of biological control and transgenic insect protection for mitigation of mycotoxins in corn

USDA-ARS?s Scientific Manuscript database

Biological control is known to be effective in reducing aflatoxin contamination of corn and some transgenic corn hybrids incur greatly reduced damage from corn earworm (Helicoverpa zea). We conducted seven field trials over two years to test the hypothesis that transgenic insect protection and biol...

The effect of Gossypolone on the growth and development of Helicoverpa zea (Boddie)

USDA-ARS?s Scientific Manuscript database

The pigment glands of the cotton plant (Gossypium) produce a group of structurally related terpenoid aldehydes that protect the plant from herbivorous insects. Of these terpenoids, the most extensively studied is gossypol. Gossypolone, a compound closely related to gossypol, has been reported in t...

Biocontrol potential of Steinernema thermophilum and its symbiont Xenorhabdus indica against lepidopteran pests: virulence to egg and larval stages

USDA-ARS?s Scientific Manuscript database

Under laboratory conditions, the biocontrol potential of Steinernema thermophilum was tested against eggs and larval stages of two important lepidopteran insect pests, Helicoverpa armigera and Spodoptera litura (polyphagous pests), as well as Galleria mellonella (used as a model host) . In terms of ...

Competitive release and outbreaks of non-target pests associated with transgenic Bt cotton

USDA-ARS?s Scientific Manuscript database

This study tests a competitive release hypothesis that Helicoverpa zea larval herbivory will 1) deter oviposition and increase leaving rates of the stink bugs, Euchistus servus and Nezara viridula and that 2) that these effects will be stronger for E. servus than for N. viridula. By spatially separa...

Re-evaluation of the PBAN receptor molecule: characterization of PBANR variants expressed in the pheromone glands of moths

USDA-ARS?s Scientific Manuscript database

Sex pheromone production in most moths is initiated following pheromone biosynthesis activating neuropeptide receptor (PBANR) activation. PBANR was initially cloned from pheromone glands (PGs) of Helicoverpa zea and Bombyx mori. The B. mori PBANR is characterized by a relatively long C-terminus that...

Spatial patterns of aflatoxin levels in relation to ear-feeding insect damage in pre-harvest corn

USDA-ARS?s Scientific Manuscript database

Key impediments to increased corn yield and quality in the southeastern US coastal plain region are damage by ear-feeding insects and aflatoxin contamination caused by infection of Aspergillus flavus. Key ear-feeding insects are corn earworm, Helicoverpa zea, fall armyworm, Spodoptera frugiperda, m...

Spatial and temporal distribution patterns of ear-feeding insect damage in pre-harvest corn

USDA-ARS?s Scientific Manuscript database

The key ear-feeding insects in the southeastern coastal plain region are the corn earworm, Helicoverpa zea (Boddie), the maize weevil, Sitophilus zeamais Motschulsky, and the brown stink bug, Euschistus servus (Say), in recent years. The population dynamics of E. servus and S. zeamais were monitore...

Spatial distribution of aflatoxin contamination in relation to damage by ear-feeding insects in pre-harvest corn

USDA-ARS?s Scientific Manuscript database

Key impediments to corn yield and quality in the southeastern coastal plain region are debatably aflatoxin contamination and damage by ear-feeding insects. The key ear-feeding insects are the corn earworm, Helicoverpa zea (Boddie), the maize weevil, Sitophilus zeamais Motschulsky, and the brown sti...

Silencing the HaHR3 Gene by Transgenic Plant-mediated RNAi to Disrupt Helicoverpa armigera Development

PubMed Central

Xiong, Yehui; Zeng, Hongmei; Zhang, Yuliang; Xu, Dawei; Qiu, Dewen

2013-01-01

RNA interference (RNAi) caused by exogenous double-stranded RNA (dsRNA) has developed into a powerful technique in functional genomics, and to date it is widely used to down-regulate crucial physiology-related genes to control pest insects. A molt-regulating transcription factor gene, HaHR3, of cotton bollworm (Helicoverpa armigera) was selected as the target gene. Four different fragments covering the coding sequence (CDS) of HaHR3 were cloned into vector L4440 to express dsRNAs in Escherichia coli. The most effective silencing fragment was then cloned into a plant over-expression vector to express a hairpin RNA (hpRNA) in transgenic tobacco (Nicotiana tabacum). When H. armigera larvae were fed the E. coli or transgenic plants, the HaHR3 mRNA and protein levels dramatically decreased, resulting developmental deformity and larval lethality. The results demonstrate that both recombinant bacteria and transgenic plants could induce HaHR3 silence to disrupt H. armigera development, transgenic plant-mediated RNAi is emerging as a powerful approach for controlling insect pests. PMID:23630449

X-ray radiation and development inhibition of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

NASA Astrophysics Data System (ADS)

Kim, Junheon; Jung, Soon-Oh; Jang, Sin Ae; Kim, Jeongmin; Park, Chung Gyoo

2015-10-01

Effect of X-ray radiation on the development inhibition was evaluated for all stages of the life cycle of Helicoverpa armigera to determine a radiation dose for potential quarantine treatment against the insect. ED99 values for inhibition of hatching, pupation, and adult emergence from irradiated eggs were 413, 210, and 154 Gy, respectively. ED99 values for inhibition of pupation and adult emergence from irradiated larvae were 221 and 167 Gy, respectively. Pupa was the most tolerant to X-ray radiation. ED99 value for inhibition of adult emergence from irradiated pupae was as high as 2310 Gy, whereas that for inhibition of F1 egg hatching was only 66 Gy. ED99 value for inhibition of hatching of F1 eggs which were laid by irradiated adults was estimated to 194 Gy. X-ray irradiation against H. armigera is recommended as an alternative method to methyl bromide fumigation for phytosanitary treatments during quarantine. X-ray radiation dose of 200 Gy is proposed as a potential quarantine treatment dose for H. armigera eggs and larvae.

Sorghum seed maturity affects the weight and feeding duration of immature corn earworm, Helicoverpa zea, and fall armyworm, Spodoptera frugiperda, in the laboratory.

PubMed

Soper, Alysha M; Whitworth, R Jeff; McCornack, Brian P

2013-01-01

Corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), and fall armyworm, Spodoptera frugiperda J.E. Smith, are occasional pests in sorghum, Sorghum bicolor L. Moench (Poales: Poaceae), and can be economically damaging when conditions are favorable. Despite the frequent occurrence of mixed-species infestations, the quantitative data necessary for developing yield loss relationships for S. frugiperda are not available. Although these species share similar biological characteristics, it is unknown whether their damage potentials in developing grain sorghum panicles are the same. Using no-choice feeding assays in the laboratory, this study examined larval growth and feeding duration for H. zea and S. frugiperda in the absence of competition. Each species responded positively when exposed to sorghum seed in the soft-dough stage, supporting evidence for the interactions between host-quality and larval growth and development. The results of this study also confirmed the suitability of using laboratory-reared H. zea to develop sorghum yield loss estimates in the field, and provided insights into the biological responses of S. frugiperda feeding on developing sorghum seed.

A sugar gustatory receptor identified from the foregut of cotton bollworm Helicoverpa armigera.

PubMed

Xu, Wei; Zhang, Hui-Jie; Anderson, Alisha

2012-12-01

Helicoverpa armigera (Hübner) is one of the most polyphagous and cosmopolitan pest species, the larvae of which feed on numerous important crops. The gustatory system is critical in guiding insect feeding behavior. Here, we identified a gustatory receptor from H. armigera, HaGR9, which shows high levels of identity to DmGR43a from Drosophila melanogaster and BmGR9 from Bombyx mori. Reverse transcriptase PCR (RT-PCR) revealed HaGR9 is highly expressed in larval foregut, with little or no expression in other chemosensory tissues. Membrane topology studies indicated that, like two previously studied B. mori GRs, BmGR8 and BmGR53, HaGR9 has an inverted topology relative to G protein-coupled receptors (GPCRs), an intracellular N-terminus and an extracellular C-terminus. Calcium imaging studies confirmed HaGR9 is a sugar receptor showing dose-dependent responses to D-galactose, D-maltose, and D-fructose. This highly-expressed foregut-specific gustatory receptor may contribute to the regulation of larval feeding behavior.

Transgenic Cotton Plants Expressing the HaHR3 Gene Conferred Enhanced Resistance to Helicoverpa armigera and Improved Cotton Yield

PubMed Central

Han, Qiang; Wang, Zhenzhen; He, Yunxin; Xiong, Yehui; Lv, Shun; Li, Shupeng; Zhang, Zhigang; Qiu, Dewen; Zeng, Hongmei

2017-01-01

RNA interference (RNAi) has been developed as an efficient technology. RNAi insect-resistant transgenic plants expressing double-stranded RNA (dsRNA) that is ingested into insects to silence target genes can affect the viability of these pests or even lead to their death. HaHR3, a molt-regulating transcription factor gene, was previously selected as a target expressed in bacteria and tobacco plants to control Helicoverpa armigera by RNAi technology. In this work, we selected the dsRNA-HaHR3 fragment to silence HaHR3 in cotton bollworm for plant mediated-RNAi research. A total of 19 transgenic cotton lines expressing HaHR3 were successfully cultivated, and seven generated lines were used to perform feeding bioassays. Transgenic cotton plants expressing dsHaHR3 were shown to induce high larval mortality and deformities of pupation and adult eclosion when used to feed the newly hatched larvae, and 3rd and 5th instar larvae of H. armigera. Moreover, HaHR3 transgenic cotton also demonstrated an improved cotton yield when compared with controls. PMID:28867769

Cannibalism Affects Core Metabolic Processes in Helicoverpa armigera Larvae—A 2D NMR Metabolomics Study

PubMed Central

Vergara, Fredd; Shino, Amiu; Kikuchi, Jun

2016-01-01

Cannibalism is known in many insect species, yet its impact on insect metabolism has not been investigated in detail. This study assessed the effects of cannibalism on the metabolism of fourth-instar larvae of the non-predatory insect Helicoverpa armigera (Lepidotera: Noctuidea). Two groups of larvae were analyzed: one group fed with fourth-instar larvae of H. armigera (cannibal), the other group fed with an artificial plant diet. Water-soluble small organic compounds present in the larvae were analyzed using two-dimensional nuclear magnetic resonance (NMR) and principal component analysis (PCA). Cannibalism negatively affected larval growth. PCA of NMR spectra showed that the metabolic profiles of cannibal and herbivore larvae were statistically different with monomeric sugars, fatty acid- and amino acid-related metabolites as the most variable compounds. Quantitation of 1H-13C HSQC (Heteronuclear Single Quantum Coherence) signals revealed that the concentrations of glucose, glucono-1,5-lactone, glycerol phosphate, glutamine, glycine, leucine, isoleucine, lysine, ornithine, proline, threonine and valine were higher in the herbivore larvae. PMID:27598144

Azadirachtin-A and tetrahydroazadirachtin-A concentrates: preparation, LC-MS characterization and insect antifeedant/IGR activity against Helicoverpa armigera (Hübner).

PubMed

Sharma, Vandana; Walia, Suresh; Dhingra, Swaran; Kumar, Jitendra; Parmar, Balraj S

2006-10-01

A 60% azadirachtin-A concentrate has been obtained through repeated precipitation with hexane from a methanolic solution of a 20% concentrate. Azadirachtin-A (90%) has been obtained by medium-pressure liquid chromatography of the 60% concentrate with an RP-18 column and a methanol + water (1 + 1 by volume) solvent system. Catalytic hydrogenation of the 60 and 90% azadirachtin concentrates yielded the corresponding tetrahydroazadirachtin concentrates. Dihydroazadirachtin and tetrahydroazadirachtin formed during the first 5 h of hydrogenation were identified by LC-ESI-MS on the basis of their unique mass fragmentation pattern. The efficacy of tetrahydroazadirachtin concentrates in inhibiting the feeding and growth of Helicoverpa armigera (Hübner) larvae has been compared with that of azadirachtin concentrates. They were in general more active and deterred larvae from feeding at all concentrations. Tetrahydroazadirachtin-A (90%) and azadirachtin-A (90%) with respective IC(50) values of 280 and 390 mg L(-1) were effective as insect growth regulators, while tetrahydroazadirachtin-A (90%) displayed higher antifeedant activity (AI(50) 14 mg L(-1)) against the test insect.

Rab3 is involved in cellular immune responses of the cotton bollworm, Helicoverpa armigera.

PubMed

Li, Jie; Song, Cai-Xia; Li, Yu-Ping; Li, Li; Wei, Xiu-Hong; Wang, Jia-Lin; Liu, Xu-Sheng

2015-06-01

Rab3, a member of the Rab GTPase family, has been found to be involved in innate immunity. However, the precise function of this GTPase in innate immunity remains unknown. In this study, we identified a Rab3 gene (Ha-Rab3) from the cotton bollworm, Helicoverpa armigera and studied its roles in innate immune responses. Expression of Ha-Rab3 was upregulated in the hemocytes of H. armigera larvae after the injection of Escherichia coli or chromatography beads. The dsRNA-mediated knockdown of Ha-Rab3 gene in H. armigera larval hemocytes led to significant reduction in the phagocytosis and nodulation activities of hemocytes against E. coli, significant increase in the bacterial load in larval hemolymph, and significant reduction in the encapsulation activities of hemocytes toward invading chromatography beads. Furthermore, Ha-Rab3 knockdown significantly suppressed spreading of plasmatocytes. These results suggest that Ha-Rab3 plays important roles in H. armigera cellular immune responses, possibly by mediating spreading of hemocytes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Sorghum Seed Maturity Affects the Weight and Feeding Duration of Immature Corn Earworm, Helicoverpa zea, and Fall Armyworm, Spodoptera frugiperda, in the Laboratory

PubMed Central

Soper, Alysha M.; Whitworth, R. Jeff; McCornack, Brian P.

2013-01-01

Corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), and fall armyworm, Spodoptera frugiperda J.E. Smith, are occasional pests in sorghum, Sorghum bicolor L. Moench (Poales: Poaceae), and can be economically damaging when conditions are favorable. Despite the frequent occurrence of mixed-species infestations, the quantitative data necessary for developing yield loss relationships for S. frugiperda are not available. Although these species share similar biological characteristics, it is unknown whether their damage potentials in developing grain sorghum panicles are the same. Using no-choice feeding assays in the laboratory, this study examined larval growth and feeding duration for H. zea and S. frugiperda in the absence of competition. Each species responded positively when exposed to sorghum seed in the soft-dough stage, supporting evidence for the interactions between host-quality and larval growth and development. The results of this study also confirmed the suitability of using laboratory-reared H. zea to develop sorghum yield loss estimates in the field, and provided insights into the biological responses of S. frugiperda feeding on developing sorghum seed. PMID:24219328

Successes and challenges of managing resistance in Helicoverpa armigera to Bt cotton in Australia.

PubMed

Downes, Sharon; Mahon, Rod

2012-01-01

Bt cotton has been gradually released and adopted by Australian growers since 1996. It was initially deployed in Australia primarily to control the polyphagous pest Helicoverpa armigera (Hübner), which in the 1990s became increasingly difficult to control due to widespread resistance to synthetic chemical insecticides. Bt-cotton has become a key tool in a program of integrated pest management for the production system that reduces pesticide dependence and the problems associated with its use. Herein we overview the deployment of Bt cotton in Australia including its performance and the approaches used to prolong the evolution of resistance to it by H. armigera. An integral component of this approach is monitoring resistance in this pest. We outline resistance screening methods, as well as the characteristics of resistant strains of H. armigera that have been isolated from field populations, or selected in the laboratory. We then highlight the successes and challenges for Bt cotton in Australia by way of discussing adaptive resistance management in light of potential changes in resistance.

Radio-induced inherited sterility in Heliothis zea (Boddie)

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

Carpenter, J.E.

1985-01-01

Heliothis zea (Boddie) (Lepidoptera: Noctuidae) males and females were irradiated with substerilizing doses of radiation. These moths were inbred and outcrossed and observed for their ability to reproduce. The inherited deleterious effects resulting from the irradiated P/sub 1/ males were recorded for several generations. Larvae from both irradiated (10 krad) and normal parents were compared for their ability to survive under field conditions on whole-stage sweet corn and these results were compared with those from a laboratory study using meridic diet. Irradiated males and females and F/sub 1/ males from an irradiated (10 krad) male x normal female cross weremore » released in the field and in field cages and observed for their ability to search/attract and secure a mate. Females that had mated with normal and irradiated (10 krad) males were studied to determine the effect of different mating histories on the subsequent mating propensity of the females. A 10-krad dose of radiation induced deleterious effects which were inherited through the F/sub 2/ generation. These radiation-induced deleterious effects were similar to those reported in other species of Lepidoptera. The relationship between the survival of normal larvae and larvae from irradiated parents was similar under laboratory and field rearing conditions. Females mated to normal males and males irradiated with 10 krad had the same mating propensity and experienced the same intermating interval. These effects of substerilizing doses of radiation and inherited sterility on the reproductive ability and behavior of H. zea suggest that a great potential exists for population suppression.« less

Genomic analysis of Oryctes rhinoceros virus reveals genetic relatedness to Heliothis zea virus 1.

PubMed

Wang, Y; van Oers, M M; Crawford, A M; Vlak, J M; Jehle, J A

2007-01-01

Oryctes rhinoceros virus (OrV) is an unassigned invertebrate dsDNA virus with enveloped and rod-shaped virions. Two cloned PstI fragments, C and D, of OrV DNA have been sequenced, consisting of 19,805 and 17,146 bp, respectively, and comprising about 30% of the OrV genome. For each of the two fragments, 20 open reading frames (ORFs) of 150 nucleotides or greater with no or minimal overlap were predicted. Ten of the predicted 40 ORFs revealed significant similarities to Heliothis zea virus 1 (HzV-1) ORFs, of which five, lef-4, lef-5, pif-2, dnapol and ac81, are homologues of conserved core genes in the family Baculoviridae, and one is homologous to baculovirus rr1. A baculovirus odv-e66 homologue is also present in OrV. Five ORFs encode proteins homologous to cellular thymidylate synthase (TS), patatin-like phospholipase, mitochondrial carrier protein, Ser/Thr protein phosphatase, and serine protease, respectively. TS is phylogenetically related to those of eukarya and nucleo-cytoplasmic large dsDNA viruses. However, the remaining 25 ORFs have poor or no sequence matches with the current databases. Both the gene content of the sequenced fragments and the phylogenetic analyses of the viral DNA polymerase suggest that OrV is most closely related to HzV-1. These findings and the re-evaluation of the relationship of HzV-1 to baculoviruses suggest that a new virus genus, Nudivirus, should be established, containing OrV and HzV-1, which are genetically related to members of the family Baculoviridae.

Transgenic pigeonpea events expressing Cry1Ac and Cry2Aa exhibit resistance to Helicoverpa armigera.

PubMed

Ghosh, Gourab; Ganguly, Shreeparna; Purohit, Arnab; Chaudhuri, Rituparna Kundu; Das, Sampa; Chakraborti, Dipankar

2017-07-01

Independent transgenic pigeonpea events were developed using two cry genes. Transgenic Cry2Aa-pigeonpea was established for the first time. Selected transgenic events demonstrated 100% mortality of Helicoverpa armigera in successive generations. Lepidopteran insect Helicoverpa armigera is the major yield constraint of food legume pigeonpea. The present study was aimed to develop H. armigera-resistant transgenic pigeonpea, selected on the basis of transgene expression and phenotyping. Agrobacterium tumefaciens-mediated transformation of embryonic axis explants of pigeonpea cv UPAS 120 was performed using two separate binary vectors carrying synthetic Bacillus thuringiensis insecticidal crystal protein genes, cry1Ac and cry2Aa. T 0 transformants were selected on the basis of PCR and protein expression profile. T 1 events were exclusively selected on the basis of expression and monogenic character for cry, validated through Western and Southern blot analyses, respectively. Independently transformed 12 Cry1Ac and 11 Cry2Aa single-copy events were developed. The level of Cry-protein expression in T 1 transgenic events was 0.140-0.175% of total soluble protein. Expressed Cry1Ac and Cry2Aa proteins in transgenic pigeonpea exhibited significant weight loss of second-fourth instar larvae of H. armigera and ultimately 80-100% mortality in detached leaf bioassay. Selected Cry-transgenic pigeonpea events, established at T 2 generation, inherited insect-resistant phenotype. Immunohistofluorescence localization in T 3 plants demonstrated constitutive accumulation of Cry1Ac and Cry2Aa in leaf tissues of respective transgenic events. This study is the first report of transgenic pigeonpea development, where stable integration, effective expression and biological activity of two Cry proteins were demonstrated in subsequent three generations (T 0 , T 1, and T 2 ). These studies will contribute to biotechnological breeding programmes of pigeonpea for its genetic improvement.

Development of neuropeptide analogs capable of traversing the integument: A case study using diapause hormone analogs in Helicoverpa zea

USDA-ARS?s Scientific Manuscript database

Diapause hormone and its analogs terminate pupal diapause in H. zea when injected, but if such agents are to be used as effective diapause disruptors it will be essential to develop simple techniques for administering active compounds that can exert their effect by penetrating the insect epidermis. ...

Effects of temperature and nonionizing ultraviolet radiation treatments of eggs of five host insects on production of Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae) for biological control applications.

USDA-ARS?s Scientific Manuscript database

Trichogramma are used worldwide as biological control against insect pests, attacking eggs of over 200 species. Eggs of Spodoptera litura, Corcyra cephalonica, Plutella xylostella and Helicoverpa armigera were tested to consider the effect of temperature and radiation on parasitization, emergence of...

Supplemental diets containing yeast, sucrose, and soy powder enhance the survivorship, growth, and development of prey-limited cursorial spiders

USDA-ARS?s Scientific Manuscript database

We examined the effects of a food spray mixture (‘wheast’) and its individual ingredients (sucrose, yeast, and toasted soy flour) on the survivorship, growth, and development of a cursorial spider, Hibana futilis Banks (Anyphaenidae). Some treatments included eggs of Helicoverpa zea, a favored prey...

genome-wide association and metabolic pathway analysis of corn earworm resistance in maize

Treesearch

Marilyn L. Warburton; Erika D. Womack; Juliet D. Tang; Adam Thrash; J. Spencer Smith; Wenwei Xu; Seth C. Murray; W. Paul Williams

2018-01-01

Maize (Zea mays mays L.) is a staple crop of economic, industrial, and food security importance. Damage to the growing ears by corn earworm [Helicoverpa zea (Boddie)] is a major economic burden and increases secondary fungal infections and mycotoxin levels. To identify biochemical pathways associated with native resistance mechanisms, a genome-wide...

Effectiveness of microbial and chemical insecticides for supplemental control of bollworm on Bt and non-Bt cottons

USDA-ARS?s Scientific Manuscript database

Laboratory and field experiments were conducted to determine the effectiveness of microbial and chemical insecticides for supplemental control of bollworm (Helicoverpa zea Boddie) on non-Bt (DP1441®) and Bt (DP1321®) cottons. Neonate and 3rd instar larvae survival were evaluated on leaf tissue treat...

Toxicity and feeding response of adult corn earworm (Lepidoptera: Noctuidae) to an organic spinosad formulation in sucrose solution

USDA-ARS?s Scientific Manuscript database

Adult corn earworm, Helicoverpa zea (Boddie), feeds on plant exudates soon after emergence from pupa in their natural habitat, and thereafter disperses to suitable host plants for reproduction. The intent of this study was to determine if Entrust™, an organic formulation of spinosad, could be used i...

Increased Helicoverpa zea (Boddie) larval feeding on cotton plants with RNAi construct CYP82D109 that blocks gossypol-related terpenoid synthesis

USDA-ARS?s Scientific Manuscript database

Glandled cotton plants, Gossypium hirsutum L., have long been known to be more resistant to insect pests compared to their glandless counterparts. This resistance has been mainly attributed to the presence of terpenoid aldehydes such as gossypol, hemigossypolone, and heliocides in the glands. We p...

Increased Helicoverpa zea (Boddie) larval feeding on a RNAi construct CYP82D109 that blocks gossypol-related terpenoid synthesis in cotton plants

USDA-ARS?s Scientific Manuscript database

Glandled cotton plants, Gossypium hirsutum L., have long been known to be more resistant to insect pests compared to their glandless counterparts. This resistance has been mainly attributed to the presence of terpenoid aldehydes such as gossypol, hemigossypolone, and heliocides in the glands. We p...

Alterations in the Helicoverpa armigera Midgut Digestive Physiology after Ingestion of Pigeon Pea Inducible Leucine Aminopeptidase

PubMed Central

Lomate, Purushottam R.; Jadhav, Bhakti R.; Giri, Ashok P.; Hivrale, Vandana K.

2013-01-01

Jasmonate inducible plant leucine aminopeptidase (LAP) is proposed to serve as direct defense in the insect midgut. However, exact functions of inducible plant LAPs in the insect midgut remain to be estimated. In the present investigation, we report the direct defensive role of pigeon pea inducible LAP in the midgut of Helicoverpa armigera (Lepidoptera: Noctuidae) and responses of midgut soluble aminopeptidases and serine proteinases upon LAP ingestion. Larval growth and survival was significantly reduced on the diets supplemented with pigeon pea LAP. Aminopeptidase activities in larvae remain unaltered in presence or absence of inducible LAP in the diet. On the contrary, serine proteinase activities were significantly decreased in the larvae reared on pigeon pea LAP containing diet as compared to larvae fed on diet without LAP. Our data suggest that pigeon pea inducible LAP is responsible for the degradation of midgut serine proteinases upon ingestion. Reduction in the aminopeptidase activity with LpNA in the H. armigera larvae was compensated with an induction of aminopeptidase activity with ApNA. Our findings could be helpful to further dissect the roles of plant inducible LAPs in the direct plant defense against herbivory. PMID:24098675

Alterations in the Helicoverpa armigera midgut digestive physiology after ingestion of pigeon pea inducible leucine aminopeptidase.

PubMed

Lomate, Purushottam R; Jadhav, Bhakti R; Giri, Ashok P; Hivrale, Vandana K

2013-01-01

Jasmonate inducible plant leucine aminopeptidase (LAP) is proposed to serve as direct defense in the insect midgut. However, exact functions of inducible plant LAPs in the insect midgut remain to be estimated. In the present investigation, we report the direct defensive role of pigeon pea inducible LAP in the midgut of Helicoverpa armigera (Lepidoptera: Noctuidae) and responses of midgut soluble aminopeptidases and serine proteinases upon LAP ingestion. Larval growth and survival was significantly reduced on the diets supplemented with pigeon pea LAP. Aminopeptidase activities in larvae remain unaltered in presence or absence of inducible LAP in the diet. On the contrary, serine proteinase activities were significantly decreased in the larvae reared on pigeon pea LAP containing diet as compared to larvae fed on diet without LAP. Our data suggest that pigeon pea inducible LAP is responsible for the degradation of midgut serine proteinases upon ingestion. Reduction in the aminopeptidase activity with LpNA in the H. armigera larvae was compensated with an induction of aminopeptidase activity with ApNA. Our findings could be helpful to further dissect the roles of plant inducible LAPs in the direct plant defense against herbivory.

Digestive proteolytic and amylolytic activities of Helicoverpa armigera in response to feeding on different soybean cultivars.

PubMed

Naseri, Bahram; Fathipour, Yaghoub; Moharramipour, Saeid; Hosseininaveh, Vahid; Gatehouse, Angharad M R

2010-12-01

Digestive proteolytic and amylolytic activities of the larvae of Helicoverpa armigera (Hübner) fed either on artificial diet or on different soybean cultivars (356, M4, M7, M9, Clark, Sahar, JK, BP, Williams, L17, Zane, Gorgan3 and DPX) and response of the larvae to feeding on some soybean-based protease inhibitors were studied. The highest general and specific proteolytic activities were in artificial-diet-fed larvae. Although the highest general proteolytic activity was in the larvae fed on L17, M4 and Sahar cultivars, the lowest tryptic activity was on L17 and Sahar, which may be due to the presence of some serine protease inhibitors in these two cultivars, resulting in hyperproduction of chymotrypsin- and elastase-like enzymes in response to the inhibition of these enzymes. The highest amylolytic activity was on M4, and the lowest was on Williams and DPX. General proteolytic activity of SKTI-fed larvae was the highest compared with SBBI- and STI-fed larvae. The findings demonstrated that the cultivars L17 and Sahar were partially resistant to this pest, probably because of some secondary chemicals or proteinaceous protease inhibitors of these cultivars.

Comparisons of contact chemoreception and food acceptance by larvae of polyphagous Helicoverpa armigera and oligophagous Bombyx mori.

PubMed

Zhang, Hui-Jie; Faucher, Cécile P; Anderson, Alisha; Berna, Amalia Z; Trowell, Stephen; Chen, Quan-Mei; Xia, Qing-You; Chyb, Sylwester

2013-08-01

We compared food choice and the initial response to deterrent treated diet between fifth instars of Helicoverpa armigera, a polyphagous generalist pest, and Bombyx mori, an oligophagous specialist beneficial. Bombyx mori was more behaviorally sensitive to salicin than to caffeine. The relative sensitivities were reversed for H. armigera, which was tolerant to the highest levels of salicin found in natural sources but sensitive to caffeine. A single gustatory receptor neuron (GRN) in the medial styloconic sensillum of B. mori was highly sensitive to salicin and caffeine. The styloconic sensilla of H. armigera did not respond consistently to either of the bitter compounds. Phagostimulants also were tested. Myo-inositol and sucrose were detected specifically by two GRNs located in B. mori lateral styloconic sensillum, whereas, in H. armigera, sucrose was sensed by a GRN in the lateral sensillum, and myo-inositol by a GRN in the medial sensillum. Myo-inositol responsiveness in both species occurred at or below 10(-3) mM, which is far below the naturally occurring concentration of 1 mM in plants. Larval responses to specific plant secondary compounds appear to have complex determinants that may include host range, metabolic capacity, and gustatory repertoire.

Differential antibiosis against Helicoverpa armigera exerted by distinct inhibitory repeat domains of Capsicum annuum proteinase inhibitors.

PubMed

Joshi, Rakesh S; Gupta, Vidya S; Giri, Ashok P

2014-05-01

Plant defensive serine proteinase inhibitors (PIs) are known to have negative impact on digestive physiology of herbivore insects and thus have a crucial role in plant protection. Here, we have assessed the efficacy and specificity of three previously characterized inhibitory repeat domain (IRD) variants from Capsicum annuum PIs viz., IRD-7, -9 and -12 against gut proteinases from Helicoverpa armigera. Comparative study of in silico binding energy revealed that IRD-9 possesses higher affinity towards H. armigera serine proteinases as compared to IRD-7 and -12. H. armigera fed on artificial diet containing 5 TIU/g of recombinant IRD proteins exhibited differential effects on larval growth, survival rate and other nutritional parameters. Major digestive gut trypsin and chymotrypsin genes were down regulated in the IRD fed larvae, while few of them were up-regulated, this indicate alterations in insect digestive physiology. The results corroborated with proteinase activity assays and zymography. These findings suggest that the sequence variations among PIs reflect in their efficacy against proteinases in vitro and in vivo, which also could be used for developing tailor-made multi-domain inhibitor gene(s). Copyright © 2014 Elsevier Ltd. All rights reserved.

Identification of novel serine proteinase gene transcripts in the midguts of two tropical insect pests, Scirpophaga incertulas (Wk.) and Helicoverpa armigera (Hb.).

PubMed

Mazumdar-Leighton, S; Babu, C R; Bennett, J

2000-01-01

We have used RT PCR and 3'RACE to identify diverse serine proteinase genes expressed in the midguts of the rice yellow stem borer (Scirpophaga incertulas) and Asian corn borer (Helicoverpa armigera). The RT-PCR primers encoded the conserved regions around the active site histidine57 and serine195 of Drosophila melanogaster alpha trypsin, including aspartate189 of the specificity pocket. These primers amplified three transcripts (SiP1-3) from midguts of S. incertulas, and two transcripts (HaP1-2) from midguts of H. armigera. The five RT PCR products were sequenced to permit design of gene-specific forward primers for use with anchored oligo dT primers in 3'RACE. Sequencing of the 3'RACE products indicated that SiP1, SiP2 and HaP1 encoded trypsin-like serine proteinases, while HaP2 encoded a chymotrypsin-like serine proteinases. The SiP3 transcript proved to be an abundant 960 nt mRNA encoding a trypsin-like protein in which the active site serine195 was replaced by aspartate. The possible functions of this unusual protein are discussed.

A novel bio-engineering approach to generate an eminent surface-functionalized template for selective detection of female sex pheromone of Helicoverpa armigera.

PubMed

Moitra, Parikshit; Bhagat, Deepa; Pratap, Rudra; Bhattacharya, Santanu

2016-11-28

Plant pests exert serious effects on food production due to which the global crop yields are reduced by ~20-40 percent per year. Hence to meet the world's food needs, loses of food due to crop pests must be reduced. Herein the silicon dioxide based MEMS devices are covalently functionalized for robust and efficient optical sensing of the female sex pheromones of the pests like Helicoverpa armigera for the first time in literature. The functionalized devices are also capable of selectively measuring the concentration of this pheromone at femtogram level which is much below the concentration of pheromone at the time of pest infestation in an agricultural field. Experiments are also performed in a confined region in the presence of male and female pests and tomato plants which directly mimics the real environmental conditions. Again the reversible use and absolutely trouble free transportation of these pheromone nanosensors heightens their potentials for commercial use. Overall, a novel and unique approach for the selective and reversible sensing of female sex pheromones of certain hazardous pests is reported herein which may be efficiently and economically carried forward from the research laboratory to the agricultural field.

Acute, sublethal, and combination effects of azadirachtin and Bacillus thuringiensis on the cotton bollworm, Helicoverpa armigera

PubMed Central

Abedi, Zahra; Saber, Moosa; Vojoudi, Samad; Mahdavi, Vahid; Parsaeyan, Ehsan

2014-01-01

Abstract The cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a polyphagous and cosmopolitan insect pest that causes damage to various plants. In this study, the lethal and sublethal effects of azadirachtin and Bacillus thuringiensis Berliner sub sp . kurstaki (Bacillales: Bacillaceae) were evaluated on third instar H. armigera under laboratory conditions. The LC50 values of azadirachtin and Bt were 12.95 and 96.8 µg a.i./mL, respectively. A total mortality of 56.7% was caused on third instar larvae when LC20 values of the insecticides were applied in combination with each other. The LT50 values of azadirachtin and Bt were 4.8 and 3.6 days, respectively. The results of the sublethal study showed that the application of LC30 value of azadirachtin and Bt reduced the larval and pupal weight and increased larval and pupal duration of H. armigera . The longevity and fecundity of female adults were affected significantly by the insecticides. Female fecundity was reduced by the treatments, respectively. The lowest adult emergence ratio and pupation ratio were observed in the azadirachtin treatment. The results indicated that both insecticides have high potential for controlling of the pest. PMID:25373177

Resurgence of the cotton bollworm Helicoverpa armigera in northern Greece associated with insecticide resistance.

PubMed

Mironidis, George K; Kapantaidaki, Despina; Bentila, Maria; Morou, Evangelia; Savopoulou-Soultani, M; Vontas, John

2013-08-01

Helicoverpa armigera has been controlled effectively with chemical insecticides in the major cotton crop production areas of northern Greece for many years. However, a resurgence of the pest was observed in 2010, which significantly affected crop production. During a 4-year survey (2007-2010), we examined the insecticide resistance status of H. armigera populations from two major and representative cotton production areas in northern Greece against seven insecticides (chlorpyrifos, diazinon, methomyl, alpha-cypermethrin, cypermethrin, gamma-cyhalothrin and endosulfan). Full dose-response bioassays on third instar larvae were performed by topical application. Lethal doses at 50% were estimated by probit analysis and resistance factors (RF) were calculated, compared to a susceptible laboratory reference strain. Resistance levels were relatively moderate until 2009, with resistance ratios below 10-fold for organophosphates and carbamates and up to 16-fold for the pyrethroid alpha-cypermethrin. However, resistance rose to 46- and 81-fold for chlorpyrifos and alpha-cypermethrin, respectively in 2010, when the resurgence of the pest was observed. None of the known pyrethroid resistance mutations were found in the pyrethroid-resistant insects. The possible association between resistance and H. armigera resurgence in Greece is discussed. © 2012 Institute of Zoology, Chinese Academy of Sciences.

A novel bio-engineering approach to generate an eminent surface-functionalized template for selective detection of female sex pheromone of Helicoverpa armigera

NASA Astrophysics Data System (ADS)

Moitra, Parikshit; Bhagat, Deepa; Pratap, Rudra; Bhattacharya, Santanu

2016-11-01

Plant pests exert serious effects on food production due to which the global crop yields are reduced by ~20-40 percent per year. Hence to meet the world’s food needs, loses of food due to crop pests must be reduced. Herein the silicon dioxide based MEMS devices are covalently functionalized for robust and efficient optical sensing of the female sex pheromones of the pests like Helicoverpa armigera for the first time in literature. The functionalized devices are also capable of selectively measuring the concentration of this pheromone at femtogram level which is much below the concentration of pheromone at the time of pest infestation in an agricultural field. Experiments are also performed in a confined region in the presence of male and female pests and tomato plants which directly mimics the real environmental conditions. Again the reversible use and absolutely trouble free transportation of these pheromone nanosensors heightens their potentials for commercial use. Overall, a novel and unique approach for the selective and reversible sensing of female sex pheromones of certain hazardous pests is reported herein which may be efficiently and economically carried forward from the research laboratory to the agricultural field.

First results of the application of a new Neemazal powder formulation in hydroponics against different pest insects.

PubMed

Hummel, Edmund; Kleeberg, Hubertus

2002-01-01

NeemAzal PC (0.5% Azadirachtin) is a new standardised powder formulation from the seed kernels of the tropical Neem tree (Azadirachta indica A. Juss) with an inert carrier. First experiments with beans--as a model-system for hydroponics--show that active ingredient is taken up by the plants through the roots and is transported efficiently with the plant sap to the leaves. After application of NeemAzal PC solution (0.01-1%) to the roots sucking (Aphis fabae Hom., Aphididae) and free feeding (Heliothis armigera Lep., Noctuidae) pest insects can be controlled efficiently. The effects are concentration and time dependent.

Peripheral Coding of Sex Pheromone Blends with Reverse Ratios in Two Helicoverpa Species

PubMed Central

Huang, Ling-Qiao; Yan, Fu-Shun; Wang, Chen-Zhu

2013-01-01

The relative proportions of components in a pheromone blend play a major role in sexual recognition in moths. Two sympatric species, Helicoverpa armigera and Helicoverpa assulta, use (Z)-11-hexadecenal (Z11–16: Ald) and (Z)-9-hexadecenal (Z9–16: Ald) as essential sex pheromone components but in very different ratios, 97∶3 and 7∶93 respectively. Using wind tunnel tests, single sensillum recording and in vivo calcium imaging, we comparatively studied behavioral responses and physiological activities at the level of antennal sensilla and antennal lobe (AL) in males of the two species to blends of the two pheromone components in different ratios (100∶0, 97∶3, 50∶50, 7∶93, 0∶100). Z11–16: Ald and Z9–16: Ald were recognized by two populations of olfactory sensory neurons (OSNs) in different trichoid sensilla on antennae of both species. The ratios of OSNs responding to Z11–16:Ald and Z9–16:Ald OSNs were 100∶28.9 and 21.9∶100 in H. armigera and H. assulta, respectively. The Z11–16:Ald OSNs in H. armigera exhibited higher sensitivity and efficacy than those in H. assulta, while the Z9–16:Ald OSNs in H. armigera had the same sensitivity but lower efficacy than those in H. assulta. At the dosage of 10 µg, Z11–16: Ald and Z9–16: Ald evoked calcium activity in 8.5% and 3.0% of the AL surface in H. armigera, while 5.4% and 8.6% of AL in H. assulta, respectively. The calcium activities in the AL reflected the peripheral input signals of the binary pheromone mixtures and correlated with the behavioral output. These results demonstrate that the binary pheromone blends were precisely coded by the firing frequency of individual OSNs tuned to Z11–16: Ald or Z9–16: Ald, as well as their population sizes. Such information was then accurately reported to ALs of H. armigera and H. assulta, eventually producing different behaviors. PMID:23894593

Sex determination of the Acadian Flycatcher using discriminant analysis

USGS Publications Warehouse

Wilson, R.R.

1999-01-01

I used five morphometric variables from 114 individuals captured in Arkansas to develop a discriminant model to predict the sex of Acadian Flycatchers (Empidonax virescens). Stepwise discriminant function analyses selected wing chord and tail length as the most parsimonious subset of variables for discriminating sex. This two-variable model correctly classified 80% of females and 97% of males used to develop the model. Validation of the model using 19 individuals from Louisiana and Virginia resulted in 100% correct classification of males and females. This model provides criteria for sexing monomorphic Acadian Flycatchers during the breeding season and possibly during the winter.

Expression of Cry2Aa, a Bacillus thuringiensis insecticidal protein in transgenic pigeon pea confers resistance to gram pod borer, Helicoverpa armigera.

PubMed

Singh, Shweta; Kumar, Nikhil Ram; Maniraj, R; Lakshmikanth, R; Rao, K Y S; Muralimohan, N; Arulprakash, T; Karthik, K; Shashibhushan, N B; Vinutha, T; Pattanayak, Debasis; Dash, Prasanta K; Kumar, P Ananda; Sreevathsa, Rohini

2018-06-11

Pigeon pea is an important legume infested by a plethora of insect pests amongst which gram pod borer Helicoverpa armigera is very prominent. Imparting resistance to this insect herbivore is of global importance in attaining food security. Expression of insecticidal crystal proteins (ICP) in diverse crops has led to increased resistance to several pests. We report in this paper, expression of Cry2Aa in transgenic pigeon pea and its effectiveness towards H. armigera by employing Agrobacterium-mediated in planta transformation approach. Approximately 0.8% of T 1 generation plants were identified as putative transformants based on screening in the presence of 70 ppm kanamycin as the selection agent. Promising events were further recognized in advanced generations based on integration, expression and bioefficacy of the transgenes. Seven T 3 lines (11.8% of the selected T1 events) were categorized as superior as these events demonstrated 80-100% mortality of the challenged larvae and improved ability to prevent damage caused by the larvae. The selected transgenic plants accumulated Cry2Aa in the range of 25-80 µg/g FW. The transgenic events developed in the study can be used in pigeon pea improvement programmes for pod borer resistance.

Mitochondrial DNA and trade data support multiple origins of Helicoverpa armigera (Lepidoptera, Noctuidae) in Brazil

PubMed Central

Tay, Wee Tek; Walsh, Thomas K.; Downes, Sharon; Anderson, Craig; Jermiin, Lars S.; Wong, Thomas K. F.; Piper, Melissa C.; Chang, Ester Silva; Macedo, Isabella Barony; Czepak, Cecilia; Behere, Gajanan T.; Silvie, Pierre; Soria, Miguel F.; Frayssinet, Marie; Gordon, Karl H. J.

2017-01-01

The Old World bollworm Helicoverpa armigera is now established in Brazil but efforts to identify incursion origin(s) and pathway(s) have met with limited success due to the patchiness of available data. Using international agricultural/horticultural commodity trade data and mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) and cytochrome b (Cyt b) gene markers, we inferred the origins and incursion pathways into Brazil. We detected 20 mtDNA haplotypes from six Brazilian states, eight of which were new to our 97 global COI-Cyt b haplotype database. Direct sequence matches indicated five Brazilian haplotypes had Asian, African, and European origins. We identified 45 parsimoniously informative sites and multiple substitutions per site within the concatenated (945 bp) nucleotide dataset, implying that probabilistic phylogenetic analysis methods are needed. High diversity and signatures of uniquely shared haplotypes with diverse localities combined with the trade data suggested multiple incursions and introduction origins in Brazil. Increasing agricultural/horticultural trade activities between the Old and New Worlds represents a significant biosecurity risk factor. Identifying pest origins will enable resistance profiling that reflects countries of origin to be included when developing a resistance management strategy, while identifying incursion pathways will improve biosecurity protocols and risk analysis at biosecurity hotspots including national ports. PMID:28350004

Elevated carboxylesterase activity contributes to the lambda-cyhalothrin insensitivity in quercetin fed Helicoverpa armigera (Hübner).

PubMed

Chen, Chengyu; Liu, Ying; Shi, Xueyan; Desneux, Nicolas; Han, Peng; Gao, Xiwu

2017-01-01

Quercetin as one of the key plant secondary metabolite flavonol is ubiquitous in terrestrial plants. In this study, the decrease in sensitivity to lambda-cyhalothrin was observed in quercetin-fed Helicoverpa armigera larvae. In order to figure out the mechanisms underlying the decreased sensitivity of H. armigera larvae to lambda-cyhalothrin by quercetin induction, the changes in carboxylesterase activity and in-vitro hydrolytic metabolic capacity to lambda-cyhalothrin were examined. The LC50 value of quercetin-fed H. armigera larvae to lambda-cyhalothrin showed 2.41-fold higher than that of the control. S, S, S-Tributyl phosphorotrithioate (DEF) treatment showed a synergism effect on lambda-cyhalothrin toxicity to quercetin-fed H. armigera. Moreover, the activity of carboxylesterase was significantly higher in quercetin-fed H. armigera larvae after fed on quercetin for 48 h. The in-vitro hydrolytic metabolic capacity to lambda-cyhalothrin in quercetin-fed H. armigera larvae midgut was 289.82 nmol 3-PBA/mg protein/min, which is significant higher than that in the control group (149.60 nmol 3-PBA/mg protein/min). The elevated CarE enzyme activity and corresponding increased hydrolytic metabolic capacity to lambda-cyhalothrin in quercetin-fed H. armigera contributed to the enhanced tolerance to lambda-cyhalothrin.

An Update on Genetic Modification of Chickpea for Increased Yield and Stress Tolerance.

PubMed

Kumar, Manoj; Yusuf, Mohd Aslam; Nigam, Manisha; Kumar, Manoj

2018-06-26

Chickpea is a highly nutritious grain legume crop, widely appreciated as a health food, especially in the Indian subcontinent. The major constraints on chickpea production are biotic (Helicoverpa, bruchid, aphid, ascochyta) and abiotic (drought, heat, salt, cold) stresses, which reduce the yield by up to 90%. Various strategies like conventional breeding, molecular breeding, and modern plant breeding have been used to overcome these problems. Conventionally, breeding programs aim at development of varieties that combine maximum number of traits through inter-specific hybridization, wide hybridization, and hybridization involving more than two parents. Breeding is difficult in this crop because of its self-pollinating nature and limited genetic variation. Recent advances in in vitro culture and gene technologies offer unique opportunities to realize the full potential of chickpea production. However, as of date, no transgenic chickpea variety has been approved for cultivation in the world. In this review, we provide an update on the development of genetically modified chickpea plants, including those resistant to Helicoverpa armigera, Callosobruchus maculatus, Aphis craccivora, as well as to drought and salt stress. The genes utilized for development of resistance against pod borer, bruchid, aphid, drought, and salt tolerance, namely, Bt, alpha amylase inhibitor, ASAL, P5CSF129A, and P5CS, respectively, are discussed.

Higher accumulation of proteinase inhibitors in flowers than leaves and fruits as a possible basis for differential feeding preference of Helicoverpa armigera on tomato (Lycopersicon esculentum Mill, Cv. Dhanashree).

PubMed

Damle, Mrunal S; Giri, Ashok P; Sainani, Mohini N; Gupta, Vidya S

2005-11-01

Tomato (Lycopersicon esculentum, Mill; cultivar- Dhanashree) proteinase inhibitors (PIs) were tested for their trypsin inhibitory (TI) and Helicoverpa armigera gut proteinases inhibitory (HGPI) activity in different organs of the tomato plants. Analysis of TI and HGPI distribution in various parts of the plant showed that flowers accumulated about 300 and 1000 times higher levels of TI while 700 and 400 times higher levels of HGPI as compared to those in leaves and fruits, respectively. Field observation that H. armigera larvae infest leaves and fruits but not the flowers could be at least partially attributed to the protective role-played by the higher levels of PIs in the flower tissue. Tomato PIs inhibited about 50-80% HGP activity of H. armigera larvae feeding on various host plants including tomato, of larvae exposed to non-host plant PIs and of various larval instars. Tomato PIs were found to be highly stable to insect proteinases wherein incubation of inhibitor with HGP even for 3h at optimum conditions did not affect inhibitory activity. Bioassay using H. armigera larvae fed on artificial diet containing tomato PIs revealed adverse effect on larval growth, pupae development, adult formation and fecundity.

Mitochondrial DNA and trade data support multiple origins of Helicoverpa armigera (Lepidoptera, Noctuidae) in Brazil.

PubMed

Tay, Wee Tek; Walsh, Thomas K; Downes, Sharon; Anderson, Craig; Jermiin, Lars S; Wong, Thomas K F; Piper, Melissa C; Chang, Ester Silva; Macedo, Isabella Barony; Czepak, Cecilia; Behere, Gajanan T; Silvie, Pierre; Soria, Miguel F; Frayssinet, Marie; Gordon, Karl H J

2017-03-28

The Old World bollworm Helicoverpa armigera is now established in Brazil but efforts to identify incursion origin(s) and pathway(s) have met with limited success due to the patchiness of available data. Using international agricultural/horticultural commodity trade data and mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) and cytochrome b (Cyt b) gene markers, we inferred the origins and incursion pathways into Brazil. We detected 20 mtDNA haplotypes from six Brazilian states, eight of which were new to our 97 global COI-Cyt b haplotype database. Direct sequence matches indicated five Brazilian haplotypes had Asian, African, and European origins. We identified 45 parsimoniously informative sites and multiple substitutions per site within the concatenated (945 bp) nucleotide dataset, implying that probabilistic phylogenetic analysis methods are needed. High diversity and signatures of uniquely shared haplotypes with diverse localities combined with the trade data suggested multiple incursions and introduction origins in Brazil. Increasing agricultural/horticultural trade activities between the Old and New Worlds represents a significant biosecurity risk factor. Identifying pest origins will enable resistance profiling that reflects countries of origin to be included when developing a resistance management strategy, while identifying incursion pathways will improve biosecurity protocols and risk analysis at biosecurity hotspots including national ports.

Mitochondrial DNA and trade data support multiple origins of Helicoverpa armigera (Lepidoptera, Noctuidae) in Brazil

NASA Astrophysics Data System (ADS)

Tay, Wee Tek; Walsh, Thomas K.; Downes, Sharon; Anderson, Craig; Jermiin, Lars S.; Wong, Thomas K. F.; Piper, Melissa C.; Chang, Ester Silva; Macedo, Isabella Barony; Czepak, Cecilia; Behere, Gajanan T.; Silvie, Pierre; Soria, Miguel F.; Frayssinet, Marie; Gordon, Karl H. J.

2017-03-01

The Old World bollworm Helicoverpa armigera is now established in Brazil but efforts to identify incursion origin(s) and pathway(s) have met with limited success due to the patchiness of available data. Using international agricultural/horticultural commodity trade data and mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) and cytochrome b (Cyt b) gene markers, we inferred the origins and incursion pathways into Brazil. We detected 20 mtDNA haplotypes from six Brazilian states, eight of which were new to our 97 global COI-Cyt b haplotype database. Direct sequence matches indicated five Brazilian haplotypes had Asian, African, and European origins. We identified 45 parsimoniously informative sites and multiple substitutions per site within the concatenated (945 bp) nucleotide dataset, implying that probabilistic phylogenetic analysis methods are needed. High diversity and signatures of uniquely shared haplotypes with diverse localities combined with the trade data suggested multiple incursions and introduction origins in Brazil. Increasing agricultural/horticultural trade activities between the Old and New Worlds represents a significant biosecurity risk factor. Identifying pest origins will enable resistance profiling that reflects countries of origin to be included when developing a resistance management strategy, while identifying incursion pathways will improve biosecurity protocols and risk analysis at biosecurity hotspots including national ports.

Elevated carboxylesterase activity contributes to the lambda-cyhalothrin insensitivity in quercetin fed Helicoverpa armigera (Hübner)

PubMed Central

Chen, Chengyu; Liu, Ying; Desneux, Nicolas; Han, Peng; Gao, Xiwu

2017-01-01

Quercetin as one of the key plant secondary metabolite flavonol is ubiquitous in terrestrial plants. In this study, the decrease in sensitivity to lambda-cyhalothrin was observed in quercetin-fed Helicoverpa armigera larvae. In order to figure out the mechanisms underlying the decreased sensitivity of H. armigera larvae to lambda-cyhalothrin by quercetin induction, the changes in carboxylesterase activity and in-vitro hydrolytic metabolic capacity to lambda-cyhalothrin were examined. The LC50 value of quercetin-fed H. armigera larvae to lambda-cyhalothrin showed 2.41-fold higher than that of the control. S, S, S-Tributyl phosphorotrithioate (DEF) treatment showed a synergism effect on lambda-cyhalothrin toxicity to quercetin-fed H. armigera. Moreover, the activity of carboxylesterase was significantly higher in quercetin-fed H. armigera larvae after fed on quercetin for 48 h. The in-vitro hydrolytic metabolic capacity to lambda-cyhalothrin in quercetin-fed H. armigera larvae midgut was 289.82 nmol 3-PBA/mg protein/min, which is significant higher than that in the control group (149.60 nmol 3-PBA/mg protein/min). The elevated CarE enzyme activity and corresponding increased hydrolytic metabolic capacity to lambda-cyhalothrin in quercetin-fed H. armigera contributed to the enhanced tolerance to lambda-cyhalothrin. PMID:28817718

Nutritional performance and activity of some digestive enzymes of the cotton bollworm, Helicoverpa armigera , in response to seven tested bean cultivars

PubMed Central

Namin, Foroogh Rahimi; Naseri, Bahram; Razmjou, Jabraeil; Cohen, Allen

2014-01-01

Abstract Nutritional performance and activity of some digestive enzymes (protease and α -amylase) of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) in response to feeding on bean ( Phaseolus vulgaris L. (Fabales: Fabaceae)) cultivars (Shokufa, Akhtar, Sayyad, Naz, Pak, Daneshkadeh, and Talash) were evaluated under laboratory conditions (25 ± 1°C, 65 ± 5% RH, and a 16:8 L:D photoperiod). The highest and lowest respective values of approximate digestibility were observed when fourth, fifth, and sixth larval instar H. armigera were fed red kidney bean Akhtar and white kidney bean Daneshkadeh. The efficiency of conversion of ingested and digested food was highest when H. armigera was fed red kidney beans Akhtar and Naz and lowest when they were fed white kidney bean Pak. The highest protease activity of fifth instars was observed when they were fed red kidney bean Naz, and the highest amylase activity of fifth instars was observed when they were fed red kidney bean Sayyad. Sixth instar larvae that fed on red kidney bean Sayyad showed the highest protease activity. Larvae reared on common bean Talash and white kidney bean Pak showed the highest amylase activity. Among bean cultivars tested, red kidney bean Sayyad was the most unsuitable host for feeding H. armigera . PMID:25368049

A novel bio-engineering approach to generate an eminent surface-functionalized template for selective detection of female sex pheromone of Helicoverpa armigera

PubMed Central

Moitra, Parikshit; Bhagat, Deepa; Pratap, Rudra; Bhattacharya, Santanu

2016-01-01

Plant pests exert serious effects on food production due to which the global crop yields are reduced by ~20–40 percent per year. Hence to meet the world’s food needs, loses of food due to crop pests must be reduced. Herein the silicon dioxide based MEMS devices are covalently functionalized for robust and efficient optical sensing of the female sex pheromones of the pests like Helicoverpa armigera for the first time in literature. The functionalized devices are also capable of selectively measuring the concentration of this pheromone at femtogram level which is much below the concentration of pheromone at the time of pest infestation in an agricultural field. Experiments are also performed in a confined region in the presence of male and female pests and tomato plants which directly mimics the real environmental conditions. Again the reversible use and absolutely trouble free transportation of these pheromone nanosensors heightens their potentials for commercial use. Overall, a novel and unique approach for the selective and reversible sensing of female sex pheromones of certain hazardous pests is reported herein which may be efficiently and economically carried forward from the research laboratory to the agricultural field. PMID:27892521

Developmental and Digestive Flexibilities in the Midgut of a Polyphagous Pest, the Cotton Bollworm, Helicoverpa armigera

PubMed Central

Sarate, P.J.; Tamhane, V.A.; Kotkar, H.M.; Ratnakaran, N.; Susan, N.; Gupta, V.S.; Giri, A.P.

2012-01-01

Developmental patterns and survival of the cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), a polyphagous insect pest, have been studied with reference to the effect of diet on major gut digestive enzymes (amylases, proteases, and lipases). Significant correlations between nutritional quality of the diet and larval and pupal mass were observed when H. armigera larvae were fed on various host plants viz. legumes (chickpea and pigeonpea), vegetables (tomato and okra), flowers (rose and marigold), and cereals (sorghum and maize). Larvae fed on diets rich in proteins and/or carbohydrates (pigeonpea, chickpea, maize, and sorghum) showed higher larval mass and developed more rapidly than larvae fed on diets with low protein and carbohydrate content (rose, marigold, okra, and tomato). Low calorific value diets like rose and marigold resulted in higher mortality (25–35%) of H. armigera. Even with highly varying development efficiency and larval/pupal survival rates, H. armigera populations feeding on different diets completed their life cycles. Digestive enzymes of H. armigera displayed variable expression levels and were found to be regulated on the basis of macromolecular composition of the diet. Post—ingestive adaptations operating at the gut level, in the form of controlled release of digestive enzymes, might be a key factor contributing to the physiological plasticity in H. armigera. PMID:22954360

Climate change, transgenic corn adoption and field-evolved resistance in corn earworm.

PubMed

Venugopal, P Dilip; Dively, Galen P

2017-06-01

Increased temperature anomaly during the twenty-first century coincides with the proliferation of transgenic crops containing the bacterium Bacillus thuringiensis (Berliner) (Bt) to express insecticidal Cry proteins. Increasing temperatures profoundly affect insect life histories and agricultural pest management. However, the implications of climate change on Bt crop-pest interactions and insect resistance to Bt crops remains unexamined. We analysed the relationship of temperature anomaly and Bt adoption with field-evolved resistance to Cry1Ab Bt sweet corn in a major pest, Helicoverpa zea (Boddie). Increased Bt adoption during 1996-2016 suppressed H. zea populations, but increased temperature anomaly buffers population reduction. Temperature anomaly and its interaction with elevated selection pressure from high Bt acreage probably accelerated the Bt-resistance development. Helicoverpa zea damage to corn ears, kernel area consumed, mean instars and proportion of late instars in Bt varieties increased with Bt adoption and temperature anomaly, through additive or interactive effects. Risk of Bt-resistant H. zea spreading is high given extensive Bt adoption, and the expected increase in overwintering and migration. Our study highlights the challenges posed by climate change for Bt biotechnology-based agricultural pest management, and the need to incorporate evolutionary processes affected by climate change into Bt-resistance management programmes.

Reproductive Cost Associated With Juvenile Hormone in Bt-Resistant Strains of Helicoverpa armigera (Lepidoptera: Noctuidae).

PubMed

Zhang, W N; Ma, L; Wang, B J; Chen, L; Khaing, M M; Lu, Y H; Liang, G M; Guo, Y Y

2016-12-01

Transgenic Bacillus thuringiensis (Bt) crops are increasingly significant in pest control, but resistance development of target pests is a major issue in the sustainable deployment of Bt crops. The fitness cost of resistance in target pests is regarded as one of the main factors delaying resistance when adopting the refuge strategy. In this study, we compared the life-history traits of three independent sets of Helicoverpa armigera (Hübner, 1809) adults, of each there were a susceptible population and a Cry1Ac-resistant population derived by selection from it. Confirming to the previous studies, resistant individuals exhibited fewer progeny, less fecundity, lower egg hatching rate, and longer adult longevity. And poor fecundity in resistant strains was associated with the decline of the mature follicular amount, the ovarian weight ratio, and the length of the longest ovarian tubule. Interestingly, the juvenile hormone (JH) level appeared higher in resistant strains relative to susceptible strains. Application of methoprene (JH analogue) in vivo was effective in reducing fecundity and hatchability with the up-regulation of detected JH titer. These results suggested that resistance against Bt toxin reduced the reproductive capacity of H. armigera, and JH level is affected in the tradeoff between reproductive capacity and Bt resistance. © Crown copyright 2016.

Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid and salicylic acid in groundnut, Arachis hypogaea.

PubMed

War, Abdul Rashid; Paulraj, Michael Gabriel; Ignacimuthu, Savarimuthu; Sharma, Hari Chand

2015-01-01

Induced resistance to Helicoverpa armigera through exogenous application of jasmonic acid (JA) and salicylic acid (SA) was studied in groundnut genotypes (ICGV 86699, ICGV 86031, ICG 2271 and ICG 1697) with different levels of resistance to insects and the susceptible check JL 24 under greenhouse conditions. Activities of oxidative enzymes and the amounts of secondary metabolites and proteins were quantified at 6 days after JA and SA application/insect infestation. Data were also recorded on plant damage and H. armigera larval weights and survival. Higher levels of enzymatic activities and amounts of secondary metabolites were observed in the insect-resistant genotypes pretreated with JA and then infested with H. armigera than in JL 24. The insect-resistant genotypes suffered lower insect damage and resulted in poor survival and lower weights of H. armigera larvae than JL 24. In some cases, JA and SA showed similar effects. JA and SA induced the activity of antioxidative enzymes in groundnut plants against H. armigera, and reduced its growth and development. However, induced response to application of JA was greater than to SA, and resulted in reduced plant damage, and larval weights and survival, suggesting that induced resistance can be used as a component of pest management in groundnut. © 2014 Society of Chemical Industry.

Analysis of several heavy metals in wild edible mushrooms from regions of China.

PubMed

Chen, Xin-Hua; Zhou, Hong-Bo; Qiu, Guan-Zhou

2009-08-01

The metal (Cu, Ni, Cd, Hg, As, Pb) contents in wild edible mushrooms collected from three different sites in China were determined by atomic absorption spectrometry and atomic fluorescence spectrometry. All element concentrations were determined on a dry weight basis. A total of 11 species was studied, five being from the urban area and six from rural areas in China. The As content ranged from 0.44 to 1.48 mg/kg. The highest As content was seen in Macrolepiota crustosa from the urban area, and the lowest in Russula virescens from rural areas. A high Ni concentration (1.35 mg/kg) was found in Calvatia craniiformis from the urban area. The lowest Ni level was 0.11 mg/kg, for the species R. virescens and Cantharellus cibarius. The Cu content ranged from 39.0 to 181.5 mg/kg. The highest Cu content was seen in Agaricus silvaticus and the lowest in C. cibarius. The Pb content ranged from 1.9 to 10.8 mg/kg. The highest Pb value was found in C. craniiformis. The Cd content ranged from 0.4 to 91.8 mg/kg. The highest Cd value was found in M. crustosa. The Hg content ranged from 0.28 to 3.92 mg/kg. The highest Hg level was found in Agaricus species. The levels of the heavy metals Cd, Pb, and Hg in the studied mushroom species from urban area can be considered high. The metal-to-metal correlation analysis supported they were the same source of contamination. High automobile traffic was identified as the most likely source of the contamination. Based upon the present safety standards, consumption of those mushrooms that grow in the polluted urban area should be avoided.

An RNAi construct of the P450 gene CYP82D109 leads to increased resistance to Fusarium oxysporum f. sp. vasinfectum (Fov11) and increased feeding by Helicoverpa Zea larvae

USDA-ARS?s Scientific Manuscript database

The P450 CYP82D109 gene codes for an early step enzyme in the gossypol pathway in Gossypium. The terminal leaves of RNAi plants had a 90% reduction in hemigossypolone and heliocides levels, and a 70% reduction in gossypol levels compared to wild-type (WT) plants. Previous studies comparing glanded...

Characterization of Three Novel SINE Families with Unusual Features in Helicoverpa armigera

PubMed Central

Wang, Jianjun; Wang, Aina; Han, Zhaojun; Zhang, Zan; Li, Fei; Li, Xianchun

2012-01-01

Although more than 120 families of short interspersed nuclear elements (SINEs) have been isolated from the eukaryotic genomes, little is known about SINEs in insects. Here, we characterize three novel SINEs from the cotton bollworm, Helicoverpa armigera. Two of them, HaSE1 and HaSE2, share similar 5′ -structure including a tRNA-related region immediately followed by conserved central domain. The 3′ -tail of HaSE1 is significantly similar to that of one LINE retrotransposon element, HaRTE1.1, in H. armigera genome. The 3′ -region of HaSE2 showed high identity with one mariner-like element in H. armigera. The third family, termed HaSE3, is a 5S rRNA-derived SINE and shares both body part and 3′-tail with HaSE1, thus may represent the first example of a chimera generated by recombination between 5S rRNA and tRNA-derived SINE in insect species. Further database searches revealed the presence of these SINEs in several other related insect species, but not in the silkworm, Bombyx mori, indicating a relatively narrow distribution of these SINEs in Lepidopterans. Apart from above, we found a copy of HaSE2 in the GenBank EST entry for the cotton aphid, Aphis gossypii, suggesting the occurrence of horizontal transfer. PMID:22319625

Silencing the HaAK Gene by Transgenic Plant-Mediated RNAi Impairs Larval Growth of Helicoverpa armigera

PubMed Central

Liu, Feng; Wang, Xiao-Dong; Zhao, Yi-Ying; Li, Yan-Jun; Liu, Yong-Chang; Sun, Jie

2015-01-01

Insect pests have caused noticeable economic losses in agriculture, and the heavy use of insecticide to control pests not only brings the threats of insecticide resistance but also causes the great pollution to foods and the environment. Transgenic plants producing double-stranded RNA (dsRNA) directed against insect genes have been is currently developed for protection against insect pests. In this study, we used this technology to silence the arginine kinase (AK) gene of Helicoverpa armigera (HaAK), encoding a phosphotransferase that plays a critical role in cellular energy metabolism in invertebrate. Transgenic Arabidopsis plants producing HaAK dsRNA were generated by Agrobacterium-mediated transformation. The maximal mortality rate of 55% was reached when H. armigera first-instar larvae were fed with transgenic plant leaves for 3 days, which was dramatically higher than the 18% mortality recorded in the control group. Moreover, the ingestion of transgenic plants significantly retarded larval growth, and the transcript levels of HaAK were also knocked down by up to 52%. The feeding bioassays further indicated that the inhibition efficiency was correlated with the integrity and concentration of the produced HaAK dsRNA in transgenic plants. These results strongly show that the resistance to H. armigera was improved in transgenic Arabidopsis plants, suggesting that the RNAi targeting of AK has the potential for the control of insect pests. PMID:25552931

Evolution of Resistance by Helicoverpa zea (Lepidoptera: Noctuidae) Infesting Insecticidal Crops in the Southern United States

PubMed Central

Onstad, David; Crain, Philip; Crespo, Andre; Hutchison, William; Buntin, David; Porter, Pat; Catchot, Angus; Cook, Don; Pilcher, Clint; Flexner, Lindsey; Higgins, Laura

2016-01-01

We created a deterministic, frequency-based model of the evolution of resistance by corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), to insecticidal traits expressed in crops planted in the heterogeneous landscapes of the southern United States. The model accounts for four generations of selection by insecticidal traits each year. We used the model results to investigate the influence of three factors on insect resistance management (IRM): 1) how does adding a third insecticidal trait to both corn and cotton affect durability of the products, 2) how does unstructured corn refuge influence IRM, and 3) how do block refuges (50% compliance) and blended refuges compare with regard to IRM? When Bt cotton expresses the same number of insecticidal traits, Bt corn with three insecticidal traits provides longer durability than Bt corn with two pyramided traits. Blended refuge provides similar durability for corn products compared with the same level of required block refuge when the rate of refuge compliance by farmers is 50%. Results for Mississippi and Texas are similar, but durabilities for corn traits are surprisingly lower in Georgia, where unstructured corn refuge is the highest of the three states, but refuge for Bt cotton is the lowest of the three states. Thus, unstructured corn refuge can be valuable for IRM but its influence is determined by selection for resistance by Bt cotton. PMID:26637533

A bifunctional α-amylase/trypsin inhibitor from pigeonpea seeds: Purification, biochemical characterization and its bio-efficacy against Helicoverpa armigera.

PubMed

Gadge, Prafull P; Wagh, Sandip K; Shaikh, Faiyaz K; Tak, Rajesh D; Padul, Manohar V; Kachole, Manvendra S

2015-11-01

This paper evaluates α-amylase inhibitor (α-AI) mediated defense of pigeonpea against Helicoverpa armigera. A bifunctional α-amylase/trypsin inhibitor was purified from the seeds of pigeonpea by native liquid phase isoelectric focusing (N-LP-IEF), affinity chromatography and preparative electrophoresis. Its in-vivo and in-vitro interaction with midgut amylases of H. armigera was studied along with growth inhibitory activity. One and two dimensional (2D) zymographic analyses revealed that the purified inhibitor is dimeric glycoprotein (60.2kDa and 56kDa) exist in a multi-isomeric form with five pI variants (pI 5.5 to 6.3). It was found to be heat labile with complete inactivation up to 80°C and stable over a wide range of pH (4-11). The slow binding and competitive type of α-amylase inhibition was observed with 0.08μM of dissociation constant (Ki) for the enzyme-inhibitor complex (EI). The internal protein sequence of two subunits obtained by mass spectrometry matched with cereal-type α-AI, a conserved domain from AAI_LTSS superfamily and sialyltransferase-like protein respectively. In-vivo studies indicated up-regulation of total midgut α-amylase activity with negative effect on growth rate of H. armigera suggesting its suitability for pest control. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterisation and inhibition studies of Helicoverpa armigera (Hübner) gut α-amylase.

PubMed

Kaur, Rimaljeet; Gupta, Anil K; Taggar, Gaurav K

2015-09-01

The survival of a devastating pest, Helicoverpa armigera, is mainly dependent on the availability of α-amylase. Therefore, characterising H. armigera α-amylase and targeting it with effective inhibitors could aid in reducing its damaging effects. H. armigera gut possessed four isozymes of α-amylase. The molecular weight of the major purified isozyme ranged from 79 to 81 kDa. The purified enzyme was identified to be α-amylase on the basis of products formed from starch. The optimum pH and temperature were 10.0 and 50 °C respectively. The activation energy was 5.7 kcal mol(-1) . The enzyme showed high activity with starch and amylopectin, whereas dextrins were poor substrates. The Michaelis constant Km with starch, amylose and amylopectin was 0.45, 1.23 and 0.11 mg mL(-1) respectively. ZnSO4 , FeSO4 , CuSO4 , citric acid, oxalic acid and salicylic acid were potent inhibitors. ZnSO4 , salicylic acid and pigeonpea α-amylase inhibitor (∼21.0 kDa) acted primarily as competitive inhibitors, FeSO4 and citric acid displayed mainly anticompetitive behaviour, while CuSO4 and oxalic acid behaved mainly as non-competitive inhibitors. The identification of effective ecofriendly inhibitors could help in managing H. armigera infestation. © 2014 Society of Chemical Industry. © 2014 Society of Chemical Industry.

Differential Induction of Flavonoids in Groundnut in Response to Helicoverpa armigera and Aphis craccivora Infestation

PubMed Central

War, Abdul Rashid; Sharma, Suraj Prasad; Sharma, Hari Chand

2016-01-01

Flavonoids are important plant secondary metabolites, which protect plants from various stresses, including herbivory. Plants differentially respond to insects with different modes of action. High performance liquid chromatography (HPLC) fingerprinting of phenols of groundnut (Arachis hypogaea) plants with differential levels of resistance was carried out in response to Helicoverpa armigera (chewing insect) and Aphis craccivora (sucking pest) infestation. The genotypes used were ICGV 86699, ICGV 86031, ICG 2271 (NCAc 343), ICG 1697 (NCAc 17090), and JL 24. Most of the identified compounds were present in H. armigera- and A. craccivora-infested plants of ICGV 86699. Syringic acid was observed in all the genotypes across the treatments, except in the uninfested control plants of ICG 2271 and aphid-infested plants of ICG 1697. Caffeic acid and umbelliferone were observed only in the H. armigera-infested plants of ICGV 86699. Similarly, dihydroxybenzoic acid and vanillic acid were observed in H. armigera- and aphid-infested plants of ICG 2271 and JL 24, respectively. The peak areas were transformed into the amounts of compounds by using internal standard peak areas and were expressed in nanograms. Quantities of the identified compounds varied across genotypes and treatments. The common compounds observed were chlorogenic, syringic, quercetin, and ferulic acids. These results suggest that depending on the mode of feeding, flavonoids are induced differentially in groundnut plants. PMID:27398031

A Lysine at the C-Terminus of an Odorant-Binding Protein is Involved in Binding Aldehyde Pheromone Components in Two Helicoverpa Species

PubMed Central

Sun, Ya-Lan; Huang, Ling-Qiao; Pelosi, Paolo; Wang, Chen-Zhu

2013-01-01

Odorant-binding proteins (OBPs) are soluble proteins, whose role in olfaction of insects is being recognized as more and more important. We have cloned, expressed and purified an OBP (HarmOBP7) from the antennae of the moth Helicoverpa armigera. Western blot experiments indicate specific expression of this protein in the antennae of adults. HarmOBP7 binds both pheromone components Z-11-hexadecenal and Z-9-hexadecenal with good affinity. We have also performed a series of binding experiments with linear aldehydes, alcohols and esters, as well as with other compounds and found a requirement of medium size for best affinity. The affinity of OBP7, as well as that of a mutant lacking the last 6 residues does not substantially decrease in acidic conditions, but increases at basic pH values with no significant differences between wild-type and mutant. Binding to both pheromone components, instead, is negatively affected by the lack of the C-terminus. A second mutant, where one of the three lysine residues in the C-terminus (Lys123) was replaced by methionine showed reduced affinity to both pheromone components, as well as to their analogues, thus indicating that Lys123 is involved in binding these compounds, likely forming hydrogen bonds with the functional groups of the ligands. PMID:23372826

Silencing of ecdysone receptor, insect intestinal mucin and sericotropin genes by bacterially produced double-stranded RNA affects larval growth and development in Plutella xylostella and Helicoverpa armigera.

PubMed

Israni, B; Rajam, M V

2017-04-01

RNA interference mediated gene silencing, which is triggered by double-stranded RNA (dsRNA), has become a important tool for functional genomics studies in various systems, including insects. Bacterially produced dsRNA employs the use of a bacterial strain lacking in RNaseIII activity and harbouring a vector with dual T7 promoter sites, which allow the production of intact dsRNA molecules. Here, we report an assessment of the functional relevance of the ecdysone receptor, insect intestinal mucin and sericotropin genes through silencing by dsRNA in two lepidopteran insect pests, Helicoverpa armigera and Plutella xylostella, both of which cause serious crop losses. Oral feeding of dsRNA led to significant reduction in transcripts of the target insect genes, which caused significant larval mortality with various moulting anomalies and an overall developmental delay. We also found a significant decrease in reproductive potential in female moths, with a drop in egg laying and compromised egg hatching from treated larvae as compared to controls. dsRNA was stable in the insect gut and was efficiently processed into small interfering RNAs (siRNAs), thus accounting for the phenotypes observed in the present work. The study revealed the importance of these genes in core insect processes, which are essential for insect development and survival. © 2016 The Royal Entomological Society.

The efficacy of Beauveria bassiana, jasmonic acid and chlorantraniliprole on larval populations of Helicoverpa armigera in chickpea crop ecosystems.

PubMed

Younas, Aneela; Wakil, Waqas; Khan, Zaeema; Shaaban, Muhammad; Prager, Sean Michael

2017-02-01

A robust integrated pest management (IPM) programme is needed to reduce the use of insecticides in controlling Helicoverpa armigera. Therefore, a 2 year field study was conducted to evaluate the use of alternative control measures (biochemical use) for H. armigera relative to exclusively using chemical insecticides. The entomopathogenic fungus Beauveria bassiana, jasmonic acid and the insecticide chlorantraniliprole were each applied twice during the chickpea growing season. All three applied materials (either alone or combined) significantly (P ≤ 0.05) reduced the larval population of H. armigera and pod infestation. Effects increased with time, and the maximum difference was observed 7 days after the second application in each year. The lowest numbers of larvae per plant and pod infestation were in the B. bassiana 3.21 × 10 6 + chlorantraniliprole treatment in both 2009/2010 and 2010/2011 year. The reduction in the larval population and pod infestation increased chickpea yield and the highest yield in both seasons, and the maximum yield was obtained in the B. bassiana 3.21 × 10 6 + chlorantraniliprole treatment. The populations of natural enemies were highest in the jasmonic acid treatment. The results suggest that B. bassiana, jasmonic acid and chlorantraniliprole may be useful components for the H. armigera IPM strategy. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Long-Term Empirical and Observational Evidence of Practical Helicoverpa zea Resistance to Cotton With Pyramided Bt Toxins.

PubMed

Reisig, Dominic D; Huseth, Anders S; Bacheler, Jack S; Aghaee, Mohammad-Amir; Braswell, Lewis; Burrack, Hannah J; Flanders, Kathy; Greene, Jeremy K; Herbert, D Ames; Jacobson, Alana; Paula-Moraes, Silvana V; Roberts, Phillip; Taylor, Sally V

2018-04-16

Evidence of practical resistance of Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) to Bt cotton in the United States is debatable, supported with occasional reports of boll damage in the field. Our objective was to provide both empirical and long-term observational evidence of practical resistance by linking both in-season and end-of-season measurements of H. zea damage to pyramided Bt cotton bolls and to provide Cry1Ac diet-based bioassay data in support of these damage estimates. In-season boll damage from H. zea was highly correlated to end-of-season damaged bolls. Across North Carolina, Bt cotton fields with end-of-season bolls damaged by H. zea increased during 2016 compared to previous years. Elevated damage was coupled with an increase in field sprays targeting H. zea during 2016, but not related to an increase in H. zea abundance. Bioassay data indicated that there was a range of Cry1Ac susceptibility across the southeastern United States. Given the range of susceptibility to Cry1Ac across the southeastern United States, it is probable that resistant populations are common. Since H. zea is resistant to cotton expressing pyramided Cry toxins, the adoption of new cotton varieties expressing Vip3Aa will be rapid. Efforts should be made to delay resistance of H. zea to the Vip3Aa toxin to avoid foliar insecticide use.

Insecticidal Potential of Defense Metabolites from Ocimum kilimandscharicum against Helicoverpa armigera

PubMed Central

Thulasiram, Hirekodathakallu V.; Kulkarni, Mahesh J.; Giri, Ashok P.

2014-01-01

Genus Ocimum contains a reservoir of diverse secondary metabolites, which are known for their defense and medicinal value. However, the defense-related metabolites from this genus have not been studied in depth. To gain deeper insight into inducible defense metabolites, we examined the overall biochemical and metabolic changes in Ocimum kilimandscharicum that occurred in response to the feeding of Helicoverpa armigera larvae. Metabolic analysis revealed that the primary and secondary metabolism of local and systemic tissues in O. kilimandscharicum was severely affected following larval infestation. Moreover, levels of specific secondary metabolites like camphor, limonene and β-caryophyllene (known to be involved in defense) significantly increased in leaves upon insect attack. Choice assays conducted by exposing H. armigera larvae on O. kilimandscharicum and tomato leaves, demonstrated that O. kilimandscharicum significantly deters larval feeding. Further, when larvae were fed on O. kilimandscharicum leaves, average body weight decreased and mortality of the larvae increased. Larvae fed on artificial diet supplemented with O. kilimandscharicum leaf extract, camphor, limonene and β-caryophyllene showed growth retardation, increased mortality rates and pupal deformities. Digestive enzymes of H. armigera - namely, amylase, protease and lipase- showed variable patterns after feeding on O. kilimandscharicum, which implies striving of the larvae to attain required nutrition for growth, development and metamorphosis. Evidently, selected metabolites from O. kilimandscharicum possess significant insecticidal activity. PMID:25098951

Trans-generational desensitization and within-generational resensitization of a sucrose-best neuron in the polyphagous herbivore Helicoverpa armigera (Lepidoptera: Noctuidae)

PubMed Central

Ma, Ying; Li, Jingjing; Tang, Qingbo; Zhang, Xuening; Zhao, Xincheng; Yan, Fengming; van Loon, Joop J. A.

2016-01-01

Dietary exposure of insects to a feeding deterrent substance for hours to days can induce habituation and concomitant desensitization of the response of peripheral gustatory neurons to such a substance. In the present study, larvae of the herbivore Helicoverpa armigera were fed on diets containing either a high, medium or low concentration of sucrose, a major feeding stimulant. The responsiveness of the sucrose-best neuron in the lateral sensilla styloconica on the galea was quantified. Results showed the response of the sucrose-best neuron exposed to high-sucrose diets decreased gradually over successive generations, resulting in complete desensitization in the 5th and subsequent generations. However, the sensitivity was completely restored in the ninth generation after neonate larvae were exposed to low-sucrose diet. These findings demonstrate phenotypic plasticity and exclude inadvertent artificial selection for low sensitivity to sucrose. No significant changes were found in the sensitivity of caterpillars which experienced low- or medium-sucrose diets over the same generations. Such desensitization versus re-sensitization did not generalise to the phagosimulant myo-inositol-sensitive neuron or the feeding deterrent-sensitive neuron. Our results demonstrate that under conditions of high sucrose availability trans-generational desensitization of a neuron sensitive to this feeding stimulant becomes more pronounced whereas re-sensitization occurs within one generation. PMID:27966640

Nitrate reductase and nitrite as additional components of defense system in pigeonpea (Cajanus cajan L.) against Helicoverpa armigera herbivory.

PubMed

Kaur, Rimaljeet; Gupta, Anil Kumar; Taggar, Gaurav Kumar

2014-10-01

Amylase inhibitors serve as attractive candidates of defense mechanisms against insect attack. Therefore, the impediment of Helicoverpa armigera digestion can be the effective way of controlling this pest population. Nitrite was found to be a potent mixed non-competitive competitive inhibitor of partially purified α-amylase of H. armigera gut. This observation impelled us to determine the response of nitrite and nitrate reductase (NR) towards H. armigera infestation in nine pigeonpea genotypes (four moderately resistant, three intermediate and two moderately susceptible). The significant upregulation of NR in moderately resistant genotypes after pod borer infestation suggested NR as one of the factors that determine their resistance status against insect attack. The pod borer attack caused greater reduction of nitrate and significant accumulation of nitrite in moderately resistant genotypes. The activity of nitrite reductase (NiR) was also enhanced more in moderately resistant genotypes than moderately susceptible genotypes on account of H. armigera herbivory. Expression of resistance to H. armigera was further revealed when significant negative association between NR, NiR, nitrite and percent pod damage was observed. This is the first report that suggests nitrite to be a potent inhibitor of H. armigera α-amylase and also the involvement of nitrite and NR in providing resistance against H. armigera herbivory. Copyright © 2014 Elsevier Inc. All rights reserved.

Recent advances of rearing cabinet instrumentation and control system for insect stock culture

NASA Astrophysics Data System (ADS)

Hermawan, Wawan; Kasmara, Hikmat; Melanie, Panatarani, Camellia; Joni, I. Made

2017-01-01

Helicoverpa armigera (Hubner) is one of a serious pest of horticulture in Indonesia. Helicoverpa armigera Nuclear Polyhedrovirus (HaNPV) has attracted interest for many researchers as a pest control for larvae of this species. Currently, we investigating the agrochemical formulations of HaNPV by introducing nanotechnology. Thus it is required an acceptable efficiency of insect stock cultures equipped with advance instruments to resolve the difficulties on insect stock seasons dependency. In addition, it is important to improve the insect survival with the aid of artificial natural environment and gain high insect production. This paper reports the rearing cabinet used as preparation of stock culture includes air-conditioning system, lighting, i.e. day and night control, and the main principles on recent technical and procedural advances apparatus of the system. The rearing system was moveable, designed and build by allowing air-conditioned cabinet for rearing insects, air motion and distribution as well as temperature and humidity being precisely controlled. The air was heated, humidified, and dehumidified respectively using a heater and ultrasonic nebulizer as actuators. Temperature and humidity can be controlled at any desired levels from room temperature (20°C) to 40 ± 1°C and from 0 to 80% RH with an accuracy of ±3% R.H. It is concluded that the recent design has acceptable performance based on the defined requirement for insect rearing and storage.

Biotechnologically generating 'super chickpea' for food and nutritional security.

PubMed

Acharjee, Sumita; Sarmah, Bidyut Kumar

2013-06-01

Chickpea productivity is affected by various constraints that are biotic (Helicoverpa, Aphids, Callosobruchus, Bromus and Orobanche) and abiotic (drought and salinity). In addition, the grains of this legume are deficient in sulfur amino acids, methionine and cysteine. The possibilities for genetic improvement by marker-assisted breeding and selection approaches are limited in chickpeas due to their sexually incompatible gene pool. Transgenic chickpeas expressing either the cry1Ac/b or the cry2Aa gene and the bean α-amylase inhibitor gene are resistant to Helicoverpa and bruchids, respectively, but these chickpeas have yet to be commercialized. Unfortunately, attempts to generate transgenic chickpeas with increased tolerance to drought and salinity or with increased methionine content have been less successful. The commercialization of transgenic chickpeas containing a single transgene may not give adequate yield advantage, as chickpeas are affected by many production constraints in the field and in storage. Gene pyramiding by incorporating two or more genes may be useful because improving one trait at a time will be time-consuming, labor-intensive and costly. Use of modern multi-gene vectors that contain recognition sites for zinc finger nucleases (ZFNs) and homing endonucleases may simplify the incorporation of multiple genes into chickpeas. This approach necessitates a collaborative effort between individuals, public and private organizations to generate 'super chickpeas' that harbor multiple transgenic traits. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Acute, sublethal, and combination effects of azadirachtin and Bacillus thuringiensis on the cotton bollworm, Helicoverpa armigera.

PubMed

Abedi, Zahra; Saber, Moosa; Vojoudi, Samad; Mahdavi, Vahid; Parsaeyan, Ehsan

2014-02-26

The cotton bollworm, Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a polyphagous and cosmopolitan insect pest that causes damage to various plants. In this study, the lethal and sublethal effects of azadirachtin and Bacillus thuringiensis Berliner sub sp . kurstaki (Bacillales: Bacillaceae) were evaluated on third instar H. armigera under laboratory conditions. The LC50 values of azadirachtin and Bt were 12.95 and 96.8 µg a.i./mL, respectively. A total mortality of 56.7% was caused on third instar larvae when LC20 values of the insecticides were applied in combination with each other. The LT50 values of azadirachtin and Bt were 4.8 and 3.6 days, respectively. The results of the sublethal study showed that the application of LC30 value of azadirachtin and Bt reduced the larval and pupal weight and increased larval and pupal duration of H. armigera. The longevity and fecundity of female adults were affected significantly by the insecticides. Female fecundity was reduced by the treatments, respectively. The lowest adult emergence ratio and pupation ratio were observed in the azadirachtin treatment. The results indicated that both insecticides have high potential for controlling of the pest. This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.

Cotton production in the presence of Helicoverpa armigera (Hb.) in Central Greece.

PubMed

Stavridis, D G; Gliatis, A; Deligeorgidis, P N; Giatropoulos, C; Giatropoulos, A; Deligeorgidis, N P; Ipsilandis, C G

2008-11-01

The present study was conducted in 10 different communities of prefecture of Larissa, one of the main cotton-productive areas of Greece. Monitoring of Helicoverpa armigera lasted four years from 2002 to 2005. The monitoring system included four locations within each community and three traps in each location. Traps were of the funnel type, a reusable injection-moulded kind of plastic trap. Pheromone was z-11-hexadecenyl aldehyde 0.36% w/w. Insecticide (Vapona) was used for all the four years, but for years 2003 and 2004 double traps were used additionally, without the presence of insecticide (only with pheromone). Traps containing a pheromone and an insecticide had significantly greater number of insects trapped than those containing no insecticide. Fluctuation of insect population was different from year to year. Correlations on data between years (insect populations and cotton production across all communities) revealed that, when cotton production was low, the number of adult male insects of H. armigera captured in pheromone traps was high (r = -0.69). There were no statistically significant correlations between cotton production and number of trapped insects when data from all communities (across the four years) were used. Local conditions within each area have been proved important and these results were completely different compared to data concerning specific years. Prediction models must be used for average estimations within great areas that include data from many locations.

Effect of Larvae Treated with Mixed Biopesticide Bacillus thuringiensis - Abamectin on Sex Pheromone Communication System in Cotton Bollworm, Helicoverpa armigera

PubMed Central

Shen, Li-Ze; Chen, Peng-Zhou; Xu, Zhi-Hong; Deng, Jian-Yu; Harris, Marvin-K; Wanna, Ruchuon; Wang, Fu-Min; Zhou, Guo-Xin; Yao, Zhang-Liang

2013-01-01

Third instar larvae of the cotton bollworm (Helicoverpa armigera) were reared with artificial diet containing a Bacillus thuringiensis - abamectin (BtA) biopesticide mixture that resulted in 20% mortality (LD20). The adult male survivors from larvae treated with BtA exhibited a higher percentage of “orientation” than control males but lower percentages of “approaching” and “landing” in wind tunnel bioassays. Adult female survivors from larvae treated with BtA produced higher sex pheromone titers and displayed a lower calling percentage than control females. The ratio of Z-11-hexadecenal (Z11–16:Ald) and Z-9-hexadecenal (Z9–16:Ald) in BtA-treated females changed and coefficients of variation (CV) of Z11–16:Ald and Z9–16:Ald were expanded compared to control females. The peak circadian calling time of BtA-treated females occurred later than that of control females. In mating choice experiment, both control males and BtA-treated males preferred to mate with control females and a portion of the Bt-A treated males did not mate whereas all control males did. Our Data support that treatment of larvae with BtA had an effect on the sex pheromone communication system in surviving H.armigera moths that may contribute to assortative mating. PMID:23874751

Members of the neuropeptide transcriptional network in Helicoverpa armigera and their expression in response to light stress.

PubMed

Wang, Lijun; Liu, Xinhui; Liu, Zhengxing; Wang, Xiaoping; Lei, Chaoliang; Zhu, Fen

2018-05-19

Neuropeptides and peptide hormones play central roles in the regulation of various types of insect physiology and behavior. Artificial light at night, a form of environmental stress, has recently been regarded as a source of light stress on nocturnal insects. Because related genomic information is not available, molecular biological studies on the response of neuropeptides in nocturnal insects to light stress are limited. Based on the de novo sequencing of the Helicoverpa armigera head transcriptome, we obtained 124,960 unigenes. Of these, the number of unigenes annotated as neuropeptides and peptide hormones, neurotransmitter precursor processing enzymes, and neurotransmitter receptors were 34, 17, and 58, respectively. Under light stress, there were sex-specific differences in gene expression measured by qRT-PCR. The IMFamide, leucokinin and sNPF genes were differentially expressed at the mRNA level in males but not in females in response to light stress. The results provide new insights on the diversity of the neuropeptide transcriptional network of H. armigera. In addition, some neuropeptides exhibited sex-specific differential expression in response to light stress. Taken collectively, these results not only expand the catalog of known insect neuropeptides but also provide a framework for future functional studies on the physiological roles they play in the light stress response behavior of nocturnal moths. Copyright © 2017. Published by Elsevier B.V.

Antennal Transcriptome Analysis and Comparison of Chemosensory Gene Families in Two Closely Related Noctuidae Moths, Helicoverpa armigera and H. assulta

PubMed Central

Zhang, Jin; Wang, Bing; Dong, Shuanglin; Cao, Depan; Dong, Junfeng; Walker, William B.; Liu, Yang; Wang, Guirong

2015-01-01

To better understand the olfactory mechanisms in the two lepidopteran pest model species, the Helicoverpa armigera and H. assulta, we conducted transcriptome analysis of the adult antennae using Illumina sequencing technology and compared the chemosensory genes between these two related species. Combined with the chemosensory genes we had identified previously in H. armigera by 454 sequencing, we identified 133 putative chemosensory unigenes in H. armigera including 60 odorant receptors (ORs), 19 ionotropic receptors (IRs), 34 odorant binding proteins (OBPs), 18 chemosensory proteins (CSPs), and 2 sensory neuron membrane proteins (SNMPs). Consistent with these results, 131 putative chemosensory genes including 64 ORs, 19 IRs, 29 OBPs, 17 CSPs, and 2 SNMPs were identified through male and female antennal transcriptome analysis in H. assulta. Reverse Transcription-PCR (RT-PCR) was conducted in H. assulta to examine the accuracy of the assembly and annotation of the transcriptome and the expression profile of these unigenes in different tissues. Most of the ORs, IRs and OBPs were enriched in adult antennae, while almost all the CSPs were expressed in antennae as well as legs. We compared the differences of the chemosensory genes between these two species in detail. Our work will surely provide valuable information for further functional studies of pheromones and host volatile recognition genes in these two related species. PMID:25659090

Identification and validation of reference genes for normalization of gene expression analysis using qRT-PCR in Helicoverpa armigera (Lepidoptera: Noctuidae).

PubMed

Zhang, Songdou; An, Shiheng; Li, Zhen; Wu, Fengming; Yang, Qingpo; Liu, Yichen; Cao, Jinjun; Zhang, Huaijiang; Zhang, Qingwen; Liu, Xiaoxia

2015-01-25

Recent studies have focused on determining functional genes and microRNAs in the pest Helicoverpa armigera (Lepidoptera: Noctuidae). Most of these studies used quantitative real-time PCR (qRT-PCR). Suitable reference genes are necessary to normalize gene expression data of qRT-PCR. However, a comprehensive study on the reference genes in H. armigera remains lacking. Twelve candidate reference genes of H. armigera were selected and evaluated for their expression stability under different biotic and abiotic conditions. The comprehensive stability ranking of candidate reference genes was recommended by RefFinder and the optimal number of reference genes was calculated by geNorm. Two target genes, thioredoxin (TRX) and Cu/Zn superoxide dismutase (SOD), were used to validate the selection of reference genes. Results showed that the most suitable candidate combinations of reference genes were as follows: 28S and RPS15 for developmental stages; RPS15 and RPL13 for larvae tissues; EF and RPL27 for adult tissues; GAPDH, RPL27, and β-TUB for nuclear polyhedrosis virus infection; RPS15 and RPL32 for insecticide treatment; RPS15 and RPL27 for temperature treatment; and RPL32, RPS15, and RPL27 for all samples. This study not only establishes an accurate method for normalizing qRT-PCR data in H. armigera but also serve as a reference for further study on gene transcription in H. armigera and other insects. Copyright © 2014 Elsevier B.V. All rights reserved.

A Brave New World for an Old World Pest: Helicoverpa armigera (Lepidoptera: Noctuidae) in Brazil

PubMed Central

Walsh, Thomas; Thomazoni, Danielle; Silvie, Pierre; Behere, Gajanan T.; Anderson, Craig; Downes, Sharon

2013-01-01

The highly polyphagous Old World cotton bollworm Helicoverpa armigera is a quarantine agricultural pest for the American continents. Historically H. armigera is thought to have colonised the American continents around 1.5 to 2 million years ago, leading to the current H. zea populations on the American continents. The relatively recent species divergence history is evident in mating compatibility between H. zea and H. armigera under laboratory conditions. Despite periodic interceptions of H. armigera into North America, this pest species is not believed to have successfully established significant populations on either continent. In this study, we provide molecular evidence via mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) and cytochrome b (Cyt b) partial gene sequences for the successful recent incursion of H. armigera into the New World, with individuals being detected at two sites (Primavera do Leste, Pedra Preta) within the State of Mato Grosso in Brazil. The mtDNA COI and Cyt b haplotypes detected in the Brazilian H. armigera individuals are common throughout the Old World, thus precluding identification of the founder populations. Combining the two partial mtDNA gene sequences showed that at least two matrilines are present in Brazil, while the inclusion of three nuclear DNA Exon-Primed Intron-Crossing (EPIC) markers identified a further two possible matrilines in our samples. The economic, biosecurity, resistance management, ecological and evolutionary implications of this incursion are discussed in relation to the current agricultural practices in the Americas. PMID:24260345

Central projections of gustatory receptor neurons in the medial and the lateral sensilla styloconica of Helicoverpa armigera larvae.

PubMed

Tang, Qing-Bo; Zhan, Huan; Cao, Huan; Berg, Bente G; Yan, Feng-Ming; Zhao, Xin-Cheng

2014-01-01

Food selection behavior of lepidopteran larvae is predominantly governed by the activation of taste neurons present in two sensilla styloconica located on the galea of the maxilla. In this study, we present the ultrastructure of the sensilla styloconica and the central projection pattern of their associated receptor neurons in larvae of the heliothine moth, Helicoverpa armigera. By means of light microscopy and scanning electron microscopy, the previous findings of two morphologically fairly similar sensilla comprising a socketed conic tip inserted into a large peg were confirmed. However, the peg size of the medial sensillum was found to be significantly bigger than that of the lateral sensillum. The sensory neurons derived from each sensillum styloconicum were mapped separately using anterograde staining experiments combined with confocal laser-scanning microscopy. For determining the afferents' target regions relative to each other, we reconstructed the labeled axons and placed them into a common reference framework. The sensory axons from both sensilla projected via the ipsilateral maxillary nerve to the suboesophageal ganglion and further through the ipsilateral circumoesophageal connective to the brain. In the suboesophageal ganglion, the sensory projections targeted two areas of the ipsilateral maxillary neuropil, one located in the ventrolateral neuromere and the other adjacent to the neuromere midline. In the brain, the axon terminals targeted the dorso-anterior area of the ipsilateral tritocerebrum. As confirmed by the three-dimensional reconstructions, the target regions of the neural projections originating from each of the two sensilla styloconica were identical.

Carbon dioxide receptor genes in cotton bollworm Helicoverpa armigera

NASA Astrophysics Data System (ADS)

Xu, Wei; Anderson, Alisha

2015-04-01

Carbon dioxide (CO2) is important in insect ecology, eliciting a range of behaviours across different species. Interestingly, the numbers of CO2 gustatory receptors (GRs) vary among insect species. In the model organism Drosophila melanogaster, two GRs (DmelGR21a and DmelGR63a) have been shown to detect CO2. In the butterfly, moth, beetle and mosquito species studied so far, three CO2 GR genes have been identified, while in tsetse flies, four CO2 GR genes have been identified. In other species including honeybees, pea aphids, ants, locusts and wasps, no CO2 GR genes have been identified from the genome. These genomic differences may suggest different mechanisms for CO2 detection exist in different insects but, with the exception of Drosophila and mosquitoes, limited attention has been paid to the CO2 GRs in insects. Here, we cloned three putative CO2 GR genes from the cotton bollworm Helicoverpa armigera and performed phylogenetic and expression analysis. All three H. armigera CO2 GRs (HarmGR1, HarmGR2 and HarmGR3) are specifically expressed in labial palps, the CO2-sensing tissue of this moth. HarmGR3 is significantly activated by NaHCO3 when expressed in insect Sf9 cells but HarmGR1 and HarmGR2 are not. This is the first report characterizing the function of lepidopteran CO2 receptors, which contributes to our general understanding of the molecular mechanisms of insect CO2 gustatory receptors.

Induced resistance by oxidative shifts in pigeonpea (Cajanus cajan L.) following Helicoverpa armigera (Hübner) herbivory.

PubMed

Kaur, Rimaljeet; Gupta, Anil K; Taggar, Gaurav K

2015-05-01

Oxidative responses in leaves, developing seeds and the pod wall of nine pigeonpea genotypes were investigated against Helicoverpa armigera feeding. Out of nine genotypes, four were moderately resistant, three were intermediate and two were moderately susceptible genotypes. A significant shift in the oxidative status of pigeonpea following herbivory was depicted by the upregulation of diamine oxidase (DAO), polyamine oxidase (PAO) and lipoxygenase 2 (LOX 2) activities. Polyphenol oxidase (PPO) activity was significantly higher in the infested pod wall and leaves of moderately resistant genotypes than in those of moderately susceptible genotypes. H. armigera infestation markedly enhanced phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) activities in wounded tissues. The decline in ascorbate peroxidase (APX) activity and ascorbate content was lower in moderately resistant genotypes than in moderately susceptible genotypes. A significant decrease in LOX 3 activity was also observed in the infested pod wall of moderately resistant and intermediate genotypes. A lower malondialdehyde (MDA) content and higher proline content of the infested pod wall and developing seeds was observed. Higher activities of PPO, PAL and proline content in leaves of uninfested moderately resistant genotypes could either be an unrelated observation or alternatively could help in identifying H. armigera-resistant genotypes. The increase in activities of PPO, DAO, PAO, PAL and TAL and higher proline and lower MDA content upon herbivory suggested their integrated contribution in providing resistance to pigeonpea against H. armigera. © 2014 Society of Chemical Industry.

Bio-potency of a 21 kDa Kunitz-type trypsin inhibitor from Tamarindus indica seeds on the developmental physiology of H. armigera.

PubMed

Pandey, Prabhash K; Jamal, Farrukh

2014-11-01

A trypsin inhibitor purified from the seeds of Tamarindus indica by Sephadex G-75, DEAE-Sepharose and Trypsin-Sepharose CL-4B columns was studied for its antifeedant, larvicidal, pupicidal and growth inhibitory activities against Helicoverpa armigera larvae. Tamarindus trypsin inhibitor (TTI) exhibited inhibitory activity towards total gut proteolytic enzymes of H. armigera (~87%) and bovine trypsin (~84%). Lethal doses which caused mortality and weight reduction by 50% were 1% w/w and 0.50% w/w, respectively. IC50 of TTI against Helicoverpa midgut proteases and bovine trypsin were ~2.10 µg/ml and 1.68 µg/ml respectively. In larval feeding studies the 21 kDa Kunitz-type protein was found to retard growth and development, prolonged the larval-pupal development durations along with adversely affecting the fertility and fecundity of H. armigera. In artificial diet at 0.5% w/w TTI, the efficiency of conversion of ingested food as well as of digested food, relative growth rate, growth index declined whereas approximate digestibility, metabolic cost, relative consumption rate, consumption index and total developmental period enhanced for H. armigera larvae. These results suggest that TTI has toxic and adverse effect on the developmental physiology of H. armigera and could be useful in controlling the pest H. armigera. Copyright © 2014 Elsevier Inc. All rights reserved.

The Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) voltage-gated sodium channel and mutations associated with pyrethroid resistance in field-collected adult males.

PubMed

Hopkins, B W; Pietrantonio, P V

2010-05-01

Helicoverpa zea is one of the most costly insect pests of food and fiber crops throughout the Americas. Pyrethroid insecticides are widely applied for its control as they are effective and relatively inexpensive; however, resistance to pyrethroids threatens agricultural systems sustainability because alternative insecticides are often more expensive or less effective. Although pyrethroid resistance has been identified in this pest since 1990, the mechanisms of resistance have not yet been elucidated at the molecular level. Pyrethroids exert their toxicity by prolonging the open state of the voltage-gated sodium channel. Here we report the cDNA sequence of the H. zea sodium channel alpha-subunit homologous to the para gene from Drosophila melanogaster. In field-collected males which were resistant to cypermethrin as determined by the adult vial test, we identify known resistance-conferring mutations L1029H and V421M, along with two novel mutations at the V421 residue, V421A and V421G. An additional mutation, I951V, may be the first example of a pyrethroid resistance mutation caused by RNA editing. Identification of the sodium channel cDNA sequence will allow for testing hypotheses on target-site resistance for insecticides acting on this channel through modeling and expression studies. Understanding the mechanisms responsible for resistance will greatly improve our ability to identify and predict resistance, as well as preserve susceptibility to pyrethroid insecticides. Copyright 2010 Elsevier Ltd. All rights reserved.

Sialome of a Generalist Lepidopteran Herbivore: Identification of Transcripts and Proteins from Helicoverpa armigera Labial Salivary Glands

PubMed Central

Celorio-Mancera, Maria de la Paz; Courtiade, Juliette; Muck, Alexander; Heckel, David G.; Musser, Richard O.; Vogel, Heiko

2011-01-01

Although the importance of insect saliva in insect-host plant interactions has been acknowledged, there is very limited information on the nature and complexity of the salivary proteome in lepidopteran herbivores. We inspected the labial salivary transcriptome and proteome of Helicoverpa armigera, an important polyphagous pest species. To identify the majority of the salivary proteins we have randomly sequenced 19,389 expressed sequence tags (ESTs) from a normalized cDNA library of salivary glands. In parallel, a non-cytosolic enriched protein fraction was obtained from labial salivary glands and subjected to two-dimensional gel electrophoresis (2-DE) and de novo peptide sequencing. This procedure allowed comparison of peptides and EST sequences and enabled us to identify 65 protein spots from the secreted labial saliva 2DE proteome. The mass spectrometry analysis revealed ecdysone, glucose oxidase, fructosidase, carboxyl/cholinesterase and an uncharacterized protein previously detected in H. armigera midgut proteome. Consistently, their corresponding transcripts are among the most abundant in our cDNA library. We did find redundancy of sequence identification of saliva-secreted proteins suggesting multiple isoforms. As expected, we found several enzymes responsible for digestion and plant offense. In addition, we identified non-digestive proteins such as an arginine kinase and abundant proteins of unknown function. This identification of secreted salivary gland proteins allows a more comprehensive understanding of insect feeding and poses new challenges for the elucidation of protein function. PMID:22046331

Regulation of the seasonal population patterns of Helicoverpa armigera moths by Bt cotton planting.

PubMed

Gao, Yu-Lin; Feng, Hong-Qiang; Wu, Kong-Ming

2010-08-01

Transgenic cotton expressing the Bacillus thuringiensis (Bt) Cry1Ac toxin has been commercially cultivated in China since 1997, and by 2000 Bt cotton had almost completely replaced non-transgenic cotton cultivars. To evaluate the impact of Bt cotton planting on the seasonal population patterns of cotton bollworm, Helicoverpa armigera, the dynamics of H. armigera moths were monitored with light traps from four locations (Xiajin, Linqing and Dingtao of Shandong Province; Guantao of Hebei Province) in high Bt density region and five locations (Anci and Xinji of Hebei Province; Dancheng and Fengqiu of Henan Province; Gaomi of Shandong Province) in low Bt density region from 1996 to 2008. A negative correlation was found between moth densities of H. armigera and the planting years of Bt cotton in both high and low Bt density areas. These data indicate that the moth population density of H. armigera was reduced with the introduction of Bt cotton in northern China. Three generations of moths occurred between early June and late September in the cotton regions. Interestingly, second-generation moths decreased and seemed to vanish in recent years in high Bt density region, but this tendency was not found in low Bt density region. The data suggest that the planting of Bt cotton in high Bt density region was effective in controlling the population density of second-generation moths. Furthermore, the seasonal change of moth patterns associated with Bt cotton planting may regulate the regional occurrence and population development of this migratory insect.

Pathways and consequences of contaminant flux to Acadian flycatchers (Empidonax virescens) in urbanizing landscapes of Ohio, USA.

PubMed

Rowse, Linnea M; Rodewald, Amanda D; Sullivan, S Mažeika P

2014-07-01

A prevalent environmental contaminant, mercury (Hg) is mobile and persistent in aquatic systems, where it often occurs in its bioavailable form methylmercury. Because methylmercury can bioaccumulate in aquatic insects and then transfer to terrestrial food webs, riparian consumers reliant upon aquatic emergent insects, should be disproportionately affected. Using the aerial insectivore Acadian flycatcher (Empidonax virescens) as a focal species, we examined (1) the extent to which total Hg loads in breeding flycatchers affected body condition and reproductive output and (2) potential pathways of contaminant flux in 19 riparian forest fragments distributed across an urban-to-rural landscape gradient in Ohio, USA. From April-August 2011-2012, we collected blood samples from adult (n=76) and nestling (n=17 from 7 nests) flycatchers, monitored their annual reproductive success (i.e., total number of fledglings), and sampled water, sediment, and aquatic emergent insects at each site. Hg concentrations in adult flycatcher blood (47 to 584 μg/kg, x¯=211.8, SD=95.5) were low relative to published advisory levels and not related to body condition. However, even at low concentrations, blood Hg was negatively related to reproductive success, with a 0.83 decline in the number of fledglings per μg/kg (loge) increase of blood Hg. Adult flycatchers had 11× greater concentrations of blood Hg than their offspring. Hg levels in flycatcher blood were not predicted by Hg concentrations in sediment, water, or aquatic emergent insects, with the exception of rural landscapes alone, in which flycatcher Hg was negatively related to sediment Hg. In addition to illustrating the difficulty of predicting exposure pathways that may vary among landscape contexts, our study provides evidence that even trace levels of contaminants may impair reproductive success of free-living songbirds. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparative study of sex pheromone composition and biosynthesis in Helicoverpa armigera, H. assulta and their hybrid.

PubMed

Wang, Hong-Lei; Zhao, Cheng-Hua; Wang, Chen-Zhu

2005-06-01

Two Helicoverpa species, H. armigera and H. assulta use (Z)-11-hexadecenal and (Z)-9-hexadecenal as their sex attractant pheromone components but in opposite ratios. Since both female and male interspecific hybrids produced by female H. assulta and male H. armigera have been obtained in our laboratory, we can make a comparative study of sex pheromone composition and biosynthesis in the two species and their hybrid. With GC and GC-MS analyses using single gland extracts, the ratio of (Z)-9-hexadecenal to (Z)-11-hexadecenal was determined as 2.1:100 in H. armigera, and 1739:100 in H. assulta. The hybrid has a ratio of 4.0: 100, which is closer to that of H. armigera, but significantly different from H. armigera. We investigated pheromone biosynthesis with labeling experiments, using various fatty acid precursors in H. armigera, H. assulta and the hybrid. In H. armigera, (Z)-11-hexadecenal is produced by delta11 desaturation of palmitic acid, followed by reduction and terminal oxidation; (Z)-9-hexadecenal results from delta11 desaturation of stearic acid, followed by one cycle of chain shortening, reduction and terminal oxidation. delta11 desaturase is the unique desaturase for the production of the two pheromone components. In our Chinese strain of H. assulta, palmitic acid is used as the substrate to form both the major pheromone component, (Z)-9-hexadecenal and the minor one, (Z)-11-hexadecenal. Our data suggest that delta9 desaturase is the major desaturase, and delta11 desaturase is responsible for the minor component in H. assulta, which is consistent with previous work. However, the weak chain shortening acting on (Z)-9 and (Z)-11-octadecenoic acid, which is present in the pheromone glands, does occur in this species to produce (Z)-7 and (Z)-9-hexadecenoic acid. In the hybrid, the major pheromone component, (Z)-11-hexadecenal is produced by delta11 desaturation of palmitic acid, followed by reduction and terminal oxidation. The direct fatty acid precursor of the minor component, (Z)-9-hexadecenoic acid is mainly produced by delta9 desaturation of palmitic acid, but also by delta11 desaturation of stearic acid and one cycle of chain shortening. The greater relative amounts of (Z)-9-hexadecenal in the hybrid are due to the fact that both palmitic and stearic acids are used as substrates, whereas only stearic acid is used as substrate in H. armigera. The evolutionary relationships between the desaturases in several Helicoverpa species are also discussed in this paper.

Oral Administration of TAT-PTD-Diapause Hormone Fusion Protein Interferes With Helicoverpa armigera (Lepidoptera: Noctuidae) Development.

PubMed

Zhou, Zhou; Li, Yongli; Yuan, Chunyan; Zhang, Yongan; Qu, Liangjian

2015-01-01

Diapause hormone (DH), which can terminate diapause in Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), has shown promise as a pest control method. However, the main challenge in using DH as an insecticide lies in achieving effective oral delivery, since the peptide may be degraded by digestive enzymes in the gut. To improve the efficacy of oral DH application, the Clostera anastomosis (L.) (Lepidoptera: Notodontidae) diapause hormone (caDH) was fused to the Protein Transduction Domain (PTD) of the human immunodeficiency virus-1 transactivator of transcription (TAT). Cellular transduction of TAT-caDH was verified with the use of a green fluorescent protein fusion, and its ability to terminate diapause was verified by injection into diapausing H. armigera pupae. Orally administered TAT-caDH resulted in larval growth inhibition. In TAT-caDH-treated insects, larval duration was delayed and the pupation rates were decreased at both development promoting conditions [27 °C, a photoperiod of 14:10(L:D) h] and diapause inducing conditions [20 °C, a photoperiod of 10:14(L:D) h]. No significant difference in diapause rate was observed between the TAT-caDH-treated and caDH-treated or control pupae maintained at diapause inducing conditions. Our results show that treatment with a recombinant TAT-caDH protein can affect larval development in H. armigera, and it suggest that TAT-DH treatment may be useful for controlling pests. This study is the first record of oral DH application in insect. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

Detection and evolution of resistance to the pyrethroid cypermethrin in Helicoverpa zea (Lepidoptera: Noctuidae) populations in Texas.

PubMed

Pietrantonio, P V; Junek, T A; Parker, R; Mott, D; Siders, K; Troxclair, N; Vargas-Camplis, J; Westbrook, J K; Vassiliou, V A

2007-10-01

The bollworm, Helicoverpa zea (Boddie), is a key pest of cotton in Texas. Bollworm populations are widely controlled with pyrethroid insecticides in cotton and exposed to pyrethroids in other major crops such as grain sorghum, corn, and soybeans. A statewide program that evaluated cypermethrin resistance in male bollworm populations using an adult vial test was conducted from 2003 to 2006 in the major cotton production regions of Texas. Estimated parameters from the most susceptible field population currently available (Burleson County, September 2005) were used to calculate resistance ratios and their statistical significance. Populations from several counties had statistically significant (P < or = 0.05) resistance ratios for the LC(50), indicating that bollworm-resistant populations are widespread in Texas. The highest resistance ratios for the LC(50) were observed for populations in Burleson County in 2000 and 2003, Nueces County in 2004, and Williamson and Uvalde Counties in 2005. These findings explain the observed pyrethroid control failures in various counties in Texas. Based on the assumption that resistance is caused by a single gene, the Hardy-Weinberg equilibrium formula was used for estimation of frequencies for the putative resistant allele (q) using 3 and 10 microg/vial as discriminatory dosages for susceptible and heterozygote resistant insects, respectively. The influence of migration on local levels of resistance was estimated by analysis of wind trajectories, which partially clarifies the rapid evolution of resistance to cypermethrin in bollworm populations. This approach could be used in evaluating resistance evolution in other migratory pests.

Emamectin benzoate: new insecticide against Helicoverpa armigera.

PubMed

Fanigliulo, A; Sacchetti, M

2008-01-01

Emamectin benzoate is a new insecticide of Syngenta Crop Protection, with a new mechanism of action and a strong activity against Lepidoptera as well as with and a high selectivity on useful organisms. This molecule acts if swallowed and has some contact action. It penetrates leaf tissues (translaminar activity) and forms a reservoir within the leaf. The mechanism of action is unique in the panorama of insecticides. In facts, it inhibits muscle contraction, causing a continuous flow of chlorine ions in the GABA and H-Glutamate receptor sites. During 2006 and 2007, experimentation was performed by the Bioagritest test facility, according to EPPO guidelines and Principles of Good Experimental Practice (GEP), aiming at establishing the biological efficacy and the selectivity of Emamectin benzoate on industry tomato against Helicoverpa armigera (Lepidoptera: Noctuidoe). The study was performed in Tursi-Policoro (Matera), southern Italy. Experimental design consisted in random blocks, in 4 repetitions. A dosage of 1.5 Kg/ha of the formulate was compared with two commercial formulates: Spinosad 0.2 kg/ha (Laser, Dow Agrosciences Italia) and Indoxacarb 0.125 kg/ha (Steward EC insecticide, Dupont). Three foliage applications were applied every 8 days. The severity of damage induced by H. armigera was evaluated on fruits. Eventual phytotoxic effects were also evaluated. Climatic conditions were optimal for Lepidoptera development, so that the percentage of fruits attacked in 2007 at the first scouting was 68.28%. Emamectin benzoate has shown, in two years of testing, a high control of H. armigera if compared with the standards Indoxacarb and Spinosad. No effect of phytotoxicity was noticed on fruits.

Baseline Susceptibility of Helicoverpa armigera (Lepidoptera: Noctuidae) to Indoxacarb, Emamectin Benzoate, and Chlorantraniliprole in Australia.

PubMed

Bird, Lisa J

2015-02-01

Baseline susceptibility of Helicoverpa armigera (Hübner) to emamectin benzoate, chlorantraniliprole, and indoxacarb was determined in feeding assays on insecticide-incorporated artificial diet in the laboratory. The intraspecific variation of H. armigera was established from field populations collected between September 2012 and March 2013, primarily from commercial farms across eastern Australia. Emamectin benzoate had the highest toxicity with a median lethal concentration (LC50) of 0.01 µg/ml diet (n=20 strains). The LC50 for chlorantraniliprole was 0.03 µg/ml diet (n=21 strains), while indoxacarb had the lowest relative toxicity with an average LC50 of 0.3 µg/ml diet (n=22 strains). Variation in susceptibility amongst field strains was 2.3-fold for emamectin benzoate and 2.9-fold for chlorantraniliprole and indoxacarb. Discriminating concentrations of 0.2, 1, and 12 µg of insecticide per milliliter of diet for emamectin benzoate, chlorantraniliprole, and indoxacarb, respectively, were calculated from toxicological data from field H. armigera strains as a first step in resistance management of these classes of insecticide in Australia. The low intraspecific tolerance, high slope values, and goodness-of-fit to a probit binomial model obtained in this study suggest that a feeding assay using diet incorporated insecticide is an effective laboratory method for measuring the dose-responses of these classes of insecticides in H. armigera. © 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.

Central Projections of Gustatory Receptor Neurons in the Medial and the Lateral Sensilla Styloconica of Helicoverpa armigera Larvae

PubMed Central

Tang, Qing-Bo; Zhan, Huan; Cao, Huan; Berg, Bente G.; Yan, Feng-Ming; Zhao, Xin-Cheng

2014-01-01

Food selection behavior of lepidopteran larvae is predominantly governed by the activation of taste neurons present in two sensilla styloconica located on the galea of the maxilla. In this study, we present the ultrastructure of the sensilla styloconica and the central projection pattern of their associated receptor neurons in larvae of the heliothine moth, Helicoverpa armigera. By means of light microscopy and scanning electron microscopy, the previous findings of two morphologically fairly similar sensilla comprising a socketed conic tip inserted into a large peg were confirmed. However, the peg size of the medial sensillum was found to be significantly bigger than that of the lateral sensillum. The sensory neurons derived from each sensillum styloconicum were mapped separately using anterograde staining experiments combined with confocal laser-scanning microscopy. For determining the afferents’ target regions relative to each other, we reconstructed the labeled axons and placed them into a common reference framework. The sensory axons from both sensilla projected via the ipsilateral maxillary nerve to the suboesophageal ganglion and further through the ipsilateral circumoesophageal connective to the brain. In the suboesophageal ganglion, the sensory projections targeted two areas of the ipsilateral maxillary neuropil, one located in the ventrolateral neuromere and the other adjacent to the neuromere midline. In the brain, the axon terminals targeted the dorso-anterior area of the ipsilateral tritocerebrum. As confirmed by the three-dimensional reconstructions, the target regions of the neural projections originating from each of the two sensilla styloconica were identical. PMID:24740428

Global Metabolomic Analyses of the Hemolymph and Brain during the Initiation, Maintenance, and Termination of Pupal Diapause in the Cotton Bollworm, Helicoverpa armigera

PubMed Central

Lu, Yu-Xuan; Zhang, Qi; Xu, Wei-Hua

2014-01-01

A strategy known as diapause (developmental arrest) has evolved in insects to increase their survival rate under harsh environmental conditions. Diapause causes a dramatic reduction in the metabolic rate and drastically extends lifespan. However, little is known about the mechanisms underlying the metabolic changes involved. Using gas chromatography-mass spectrometry, we compared the changes in the metabolite levels in the brain and hemolymph of nondiapause- and diapause-destined cotton bollworm, Helicoverpa armigera, during the initiation, maintenance, and termination of pupal diapause. A total of 55 metabolites in the hemolymph and 52 metabolites in the brain were detected. Of these metabolites, 21 and 12 metabolite levels were altered in the diapause pupal hemolymph and brain, respectively. During diapause initiation and maintenance, the number of metabolites with increased levels in the hemolymph of the diapausing pupae is far greater than the number in the nondiapause pupae. These increased metabolites function as an energy source, metabolic intermediates, and cryoprotectants. The number of metabolites with decreased levels in the brain of diapausing pupae is far greater than the number in the nondiapause pupae. Low metabolite levels are likely to directly or indirectly repress the brain metabolic activity. During diapause termination, most of the metabolite levels in the hemolymph of the diapausing pupae rapidly decrease because they function as energy and metabolic sources that promote pupa-adult development. In conclusion, the metabolites with altered levels in the hemolymph and brain serve as energy and metabolic resources and help to maintain a low brain metabolic activity during diapause. PMID:24926789

Tarsal taste neuron activity and proboscis extension reflex in response to sugars and amino acids in Helicoverpa armigera (Hubner).

PubMed

Zhang, Yun-Feng; van Loon, Joop J A; Wang, Chen-Zhu

2010-08-15

In adult female Helicoverpa armigera (Hübner), the fifth tarsomere of the prothoracic legs bears 14 gustatory trichoid chemosensilla. These chemosensilla were characterized through electrophysiological experiments by stimulating with sucrose, glucose, fructose, maltose, myo-inositol and 20 common amino acids. In electrophysiological recordings from nine sensilla, responses were obtained to certain compounds tested at 100 mmol l(-1), and the response spectra differed from broad to narrow. The four sugars excited the same receptor neuron in sensillum a and sensillum b; sucrose and myo-inositol, sucrose and lysine, myo-inositol and lysine excited two different receptor neurons respectively in sensillum a; fructose and lysine excited two different receptor neurons in sensillum n. Furthermore, the four sugars, myo-inositol and lysine all elicited concentration-dependent electrophysiological responses. These six compounds also induced the proboscis extension reflex (PER) followed by ingestion of the solution when they were applied on the tarsi. Lysine and sucrose caused the strongest electrophysiological responses. However, sucrose had the strongest stimulatory effect on the PER whereas lysine had the weakest. Mixtures of sucrose with the other sugars or with lysine had a similar stimulatory effect on the PER as sucrose alone. The electrophysiological and behavioural responses caused by a range of sucrose concentrations were positively correlated. We conclude that the tarsal gustatory sensilla play an essential role in perceiving sugars available in floral nectar and provide chemosensory information determining feeding behaviour. Tarsal taste-receptor-neuron responses to lysine are implicated in oviposition behaviour.

Silencing of HaAce1 gene by host-delivered artificial microRNA disrupts growth and development of Helicoverpa armigera.

PubMed

Saini, Ravi Prakash; Raman, Venkat; Dhandapani, Gurusamy; Malhotra, Era Vaidya; Sreevathsa, Rohini; Kumar, Polumetla Ananda; Sharma, Tilak R; Pattanayak, Debasis

2018-01-01

The polyphagous insect-pest, Helicoverpa armigera, is a serious threat to a number of economically important crops. Chemical application and/or cultivation of Bt transgenic crops are the two strategies available now for insect-pest management. However, environmental pollution and long-term sustainability are major concerns against these two options. RNAi is now considered as a promising technology to complement Bt to tackle insect-pests menace. In this study, we report host-delivered silencing of HaAce1 gene, encoding the predominant isoform of H. armigera acetylcholinesterase, by an artificial microRNA, HaAce1-amiR1. Arabidopsis pre-miRNA164b was modified by replacing miR164b/miR164b* sequences with HaAce1-amiR1/HaAce1-amiR1* sequences. The recombinant HaAce1-preamiRNA1 was put under the control of CaMV 35S promoter and NOS terminator of plant binary vector pBI121, and the resultant vector cassette was used for tobacco transformation. Two transgenic tobacco lines expressing HaAce1-amiR1 was used for detached leaf insect feeding bioassays. Larval mortality of 25% and adult deformity of 20% were observed in transgenic treated insect group over that control tobacco treated insect group. The reduction in the steady-state level of HaAce1 mRNA was 70-80% in the defective adults compared to control. Our results demonstrate promise for host-delivered amiRNA-mediated silencing of HaAce1 gene for H. armigera management.

Effectiveness of two insect growth regulators against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) and their impact on population densities of arthropod predators in cotton in Pakistan.

PubMed

Gogi, Muhammad D; Sarfraz, Rana M; Dosdall, Lloyd M; Arif, Muhammad J; Keddie, Andrew B; Ashfaq, Muhammad

2006-10-01

Field efficacies of two insect growth regulators (IGRs) at two recommended application rates, buprofezin at 370 and 555 g AI ha(-1) and lufenuron at 37 and 49 g AI ha(-1), were determined against the sweet potato whitefly, Bemisia tabaci (Gennadius), and the cotton bollworm, Helicoverpa armigera (Hübner), in experimental plots of cotton at the Directorate of Cotton Research, Faisalabad, Pakistan. Adverse effects of the IGRs on populations of associated arthropod predators, namely geocorids, chrysopids, coccinellids, formicids and arachnids, were also assessed. Both IGRs significantly reduced populations of B. tabaci at each application rate 24, 48 and 72 h after treatment, and higher doses were more effective than lower doses. Buprofezin was not effective against H. armigera at any tested dose for any time of treatment in any spray. Lufenuron applied at 37 and 49 g AI ha(-1) effectively suppressed H. armigera populations, resulting in significant reductions in crop damage. At lower doses, both IGRs appeared safe to predator populations, which did not differ significantly in IGR-treated versus untreated control plots. Population densities of formicids and coccinellids were significantly lower at high concentrations of both IGRs in treatment plots, possibly as a result of reduced prey availability. The potential role of buprofezin and lufenuron for control of B. tabaci and H. armigera in a spray programme and the likelihood of direct toxic effects of IGRs on predatory fauna of cotton are discussed.

Acute, sublethal and combination effects of azadirachtin and Bacillus thuringiensis toxins on Helicoverpa armigera (Lepidoptera: Noctuidae) larvae.

PubMed

Singh, G; Rup, P J; Koul, Opender

2007-08-01

The efficacy of neem (1500 ppm azadirachtin (AI)), Delfin WG, a biological insecticide based on selected strain of Bacillus thuringiensis Berliner (Bt) subspecies kurstaki, and Cry1Ac protein, either individually or in combination, were examined against first to fourth instar Helicoverpa armigera (Hübner) larvae. Using an oral administration method, various growth inhibitory concentrations (EC) and lethal concentrations (LC) were determined for each bioagent. Combinations of sublethal concentrations of Bt spray formulation with azadirachtin at EC50 or EC95 levels not only enhanced the toxicity, but also reduced the duration of action when used in a mixture. The LC20 and LC50 values for Cry1Ac toxin were 0.06 and 0.22 microg ml-1, respectively. Bt-azadirachtin combinations of LC50+EC20 and LC50+EC50 result in 100% mortality. The mortality also was significant in LC20+EC20 and LC20+EC50 mixtures. These studies imply that the combined action is not synergistic but complimentary, with azadirachtin particularly facilitating the action of Bt. The Bt spray-azadirachtin combination is more economical than combinations that involve isolating the toxic protein, as the Bt spray formulations can be combined in a spray mixture with neem. These combinations may be useful for controlling bollworm populations that have acquired resistance to Bt as they may not survive the effect of mixture. Azadirachtin may be useful as a means of reducing the endotoxin concentrations in a mixture, to promote increased economic savings and further reduce the probability of resistance development to either insect control agent.

Recovery of Infectious Pariacoto Virus from cDNA Clones and Identification of Susceptible Cell Lines

PubMed Central

Johnson, Karyn N.; Ball, L. Andrew

2001-01-01

Pariacoto virus (PaV) is a nodavirus that was recently isolated in Peru from the Southern armyworm, Spodoptera eridania. Virus particles are non enveloped and about 30 nm in diameter and have T=3 icosahedral symmetry. The 3.0-Å crystal structure shows that about 35% of the genomic RNA is icosahedrally ordered, with the RNA forming a dodecahedral cage of 25-nucleotide (nt) duplexes that underlie the inner surface of the capsid. The PaV genome comprises two single-stranded, positive-sense RNAs: RNA1 (3,011 nt), which encodes the 108-kDa catalytic subunit of the RNA-dependent RNA polymerase, and RNA2 (1,311 nt), which encodes the 43-kDa capsid protein precursor α. In order to apply molecular genetics to the structure and assembly of PaV, we identified susceptible cell lines and developed a reverse genetic system for this virus. Cell lines that were susceptible to infection by PaV included those from Spodoptera exigua, Helicoverpa zea and Aedes albopictus, whereas cells from Drosophila melanogaster and Spodoptera frugiperda were refractory to infection. To recover virus from molecular clones, full-length cDNAs of PaV RNAs 1 and 2 were cotranscribed by T7 RNA polymerase in baby hamster kidney cells that expressed T7 RNA polymerase. Lysates of these cells were infectious both for cultured cells from Helicoverpa zea (corn earworm) and for larvae of Galleria mellonella (greater wax moth). The combination of infectious cDNA clones, cell culture infectivity, and the ability to produce milligram amounts of virus allows the application of DNA-based genetic methods to the study of PaV structure and assembly. PMID:11711613

Effect of electron beam irradiation on developmental stages of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

NASA Astrophysics Data System (ADS)

Kim, Junheon; Chung, Soon-Oh; Jang, Sin Ae; Jang, Miyeon; Park, Chung Gyoo

2015-07-01

Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), is an economically important and polyphagous pest, which harms various kinds of food crops and important agricultural plants, such as cotton and paprika. Effects of electron beam irradiation at six dose levels between 50 and 350 Gy on the egg (24-48 h old), the larval (4-5th instar), and the pupal (7-d old for female, 5-d old for male) development, and on the adult (1-d old) reproduction were tested to identify a potential quarantine treatment dose. Increased doses of irradiation on eggs decreased egg hatchability, pupation and adult emergence and increased larval period. ED99 values for inhibition of hatching, pupation and emergence were 460.6, 236.9 and 197.8 Gy, respectively. When larvae were irradiated with more than 280 Gy, no larvae could develop into pupae. ED99 values for inhibition of pupation and adult emergence were 265.6 and 189.6 Gy, respectively. Even though the irradiation on pupa did not completely inhibit adult emergence, most of the pupae emerged to deformed adults. When adults were irradiated, fecundity was not affected. However, F1 egg hatching was completely inhibited at the dose of 350 Gy. ED99 value for inhibition of adult emergence was estimated at 366.5 Gy. Our results suggest that electron beam irradiation could be recommendable as an alternative to MB and as a phytosanitary treatment for quarantine. A treatment dose of less than or equal to 220 Gy is suggested as a potential quarantine treatment to H. armigera egg for prevention of pupation and to larva for prevention of adult emerge.

Development, survival and fitness performance of Helicoverpa zea (Lepidoptera: Noctuidae) in MON810 Bt field corn.

PubMed

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

2003-06-01

Helicoverpa zea (Boddie) development, survival, and feeding injury in MON810 transgenic ears of field corn (Zea mays L.) expressing Bacillus thuringiensis variety kurstaki (Bt) Cry1Ab endotoxins were compared with non-Bt ears at four geographic locations over two growing seasons. Expression of Cry1Ab endotoxin resulted in overall reductions in the percentage of damaged ears by 33% and in the amount of kernels consumed by 60%. Bt-induced effects varied significantly among locations, partly because of the overall level and timing of H. zea infestations, condition of silk tissue at the time of egg hatch, and the possible effects of plant stress. Larvae feeding on Bt ears produced scattered, discontinuous patches of partially consumed kernels, which were arranged more linearly than the compact feeding patterns in non-Bt ears. The feeding patterns suggest that larvae in Bt ears are moving about sampling kernels more frequently than larvae in non-Bt ears. Because not all kernels express the same level of endotoxin, the spatial heterogeneity of toxin distribution within Bt ears may provide an opportunity for development of behavioral responses in H. zea to avoid toxin. MON810 corn suppressed the establishment and development of H. zea to late instars by at least 75%. This level of control is considered a moderate dose, which may increase the risk of resistance development in areas where MON810 corn is widely adopted and H. zea overwinters successfully. Sublethal effects of MON810 corn resulted in prolonged larval and prepupal development, smaller pupae, and reduced fecundity of H. zea. The moderate dose effects and the spatial heterogeneity of toxin distribution among kernels could increase the additive genetic variance for both physiological and behavioral resistance in H. zea populations. Implications of localized population suppression are discussed.

Comparative Feeding Performance and Digestive Physiology of Helicoverpa armigera (Lepidoptera: Noctuidae) Larvae-Fed 11 Corn Hybrids

PubMed Central

Hosseininejad, A. S.; Naseri, B.; Razmjou, J.

2015-01-01

This study aimed to evaluate the feeding responses and digestive proteolytic and amylolytic activity of Helicoverpa armigera (Hübner) on 11 corn (Zea mays L.) hybrids at 25 ± 1°C, 65 ± 5% relative humidity (RH), and a photoperiod of 16:8 (L:D) h. The fourth- and fifth-instar larvae fed on hybrid K47*K19 had the highest weight of food consumption and those reared on hybrid KSC705 had the lowest value of food consumption. The highest weight gain of the larvae was observed when H. armigera were fed hybrid KLM78*MO17 and lowest when they were fed hybrids K36 * MO17, KSC705, and K35 * K36. Pupal weight of H. armigera was heaviest when larvae were fed hybrid K47*K19 and lightest when they were fed hybrid KSC705. The highest proteolytic activity of the fourth-instar larvae was observed when they were fed hybrid KSC705, and the lowest activity was observed when they were fed hybrid K47*A67. Fifth-instar larvae that fed on hybrid K47*K19 showed the highest proteolytic activity. Fourth-instar larvae that fed on hybrid K36*MO17 showed the highest amylase activity. The fifth-instar larvae fed on hybrid K47*A67 showed the maximum amylase activity and those reared on the K48*K18 showed the minimum activity. Our results indicated that K36 * MO17, KSC705, and K48 * K18 were the most unsuitable hybrids for feeding H. armigera. PMID:25688090

Biochemical, structural and functional diversity between two digestive α-amylases from Helicoverpa armigera.

PubMed

Bhide, Amey J; Channale, Sonal M; Patil, Sucheta S; Gupta, Vidya S; Ramasamy, Sureshkumar; Giri, Ashok P

2015-09-01

Helicoverpa armigera (Lepidoptera) feeds on various plants using diverse digestive enzymes as one of the survival tool-kit. The aim of the present study was to understand biochemical properties of recombinant α-amylases of H. armigera viz., HaAmy1 and HaAmy2. The open reading frames of HaAmy1 and HaAmy2 were cloned in Pichia pastoris and expressed heterologously. Purified recombinant enzymes were characterized for their biochemical and biophysical attributes using established methods. Sequence alignment and homology modeling showed that HaAmy1 and HaAmy2 were conserved in their amino acid sequences and structures. HaAmy1 and HaAmy2 showed optimum activity at 60°C; however, they differed in their optimum pH. Furthermore, HaAmy2 showed higher affinity for starch and amylopectin whereas HaAmy1 had higher catalytic efficiency. HaAmy1 and HaAmy2 were inhibited to the same magnitude by a synthetic amylase inhibitor (acarbose) while wheat amylase inhibitor showed about 2-fold higher inhibition of HaAmy1 than HaAmy2 at pH7 while 6-fold difference at pH11. Interactions of HaAmy1 and HaAmy2 with wheat amylase inhibitor revealed 2:1 stoichiometric ratio and much more complex interaction with HaAmy1. The diversity of amylases in perspective of their biochemical and biophysical properties, and their differential interactions with amylase inhibitors signify the potential role of these enzymes in adaptation of H. armigera on diverse plant diets. Characterization of digestive enzymes of H. armigera provides the molecular basis for the polyphagous nature and thus could assist in designing future strategies for the insect control. Copyright © 2015 Elsevier B.V. All rights reserved.

The First Cry2Ac-Type Protein Toxic to Helicoverpa armigera: Cloning and Overexpression of Cry2ac7 Gene from SBS-BT1 Strain of Bacillus thuringiensis

PubMed Central

Saleem, Faiza; Shakoori, Abdul Rauf

2017-01-01

The Cry (crystal) proteins from Bacillus thuringiensis are known to have toxicity against a variety of insects and have been exploited to control insect pests through transgenic plants and biopesticides. B. thuringiensis SBS BT-1 carrying the cry2 genes was isolated from soil samples in Pakistan. The 2-kb full length cry2Ac gene was cloned, sequenced, and submitted to the EMBL DNA database (Accession No. AM292031). For expression analysis, Escherichia coli DH5α was transformed with the fragment sub-cloned in pET22b expression vector using NdeI and HindIII restriction sites, and later confirmed by restriction endonuclease analysis. To assess the toxicity of Cry2Ac7 protein against lepidopteran and dipteran insects, BL21 (codon plus) strain of E. coli was further transformed with the recombinant plasmid. The 65-kDa protein was expressed in the form of inclusion bodies up to 180 OD units per liter of the medium. Inclusions were washed with a buffer containing 1.5% Triton-X 100 and >90% pure Cry2Ac7 was obtained. The inclusion bodies were dissolved in 50 mM K2CO3 (pH 11.5), dialyzed, and freeze-dried. This freeze-dried protein as well as inclusion bodies were used in bioassays against larvae of Helicoverpa armigera and Musca domestica. The freeze-dried protein was toxic to H. armigera larvae with an LC50 value of 131 ng/mL. However, Cry2Ac7 produced in E. coli did not show any mortality to M. domestica larvae. This is the first report of Cry2Ac protein toxic to H. armigera. PMID:29099767

Heterologous expression of Helicoverpa armigera cytochrome P450 CYP6B7 in Pichia pastoris and interactions of CYP6B7 with insecticides.

PubMed

Zhao, Chunqing; Song, Genmiao; Duan, Hongxia; Tang, Tao; Wang, Chen; Qiu, Lihong

2017-09-01

Previous studies indicated that constitutive over-expression of cytochrome P450 CYP6B7 was involved in fenvalerate resistance in Helicoverpa armigera. In this study, the CYP6B7 gene from H. armigera (namely HaCYP6B7), was heterologously expressed in Pichia pastoris GS115. A vector pPICZA-HaCYP6B7 was constructed and transformed into P. pastoris GS115, the transformant of pPICZA-HaCYP6B7-GS115 was then cultured and induced by 1% (v/v) methanol and the heterologous expression of HaCYP6B7 protein in P. pastoris was confirmed by SDS-PAGE and western blot. Microsomes containing the expressed HaCYP6B7 showed activities against model substrate p-nitroanisole and 7-ethoxycoumarin, with p-nitroanisole O-demethylation (PNOD) and 7-ethoxycoumarin O-deethylation (ECOD) activities of 15.66- and 4.75-fold of the control, respectively. Moreover, it showed degradation activities against the insecticides bifenthrin, fenvalerate and chlorpyrifos, with clearance activities of 6.88-, 1.49- and 2.27-fold of the control, respectively. The interactions of HaCYP6B7 with insecticides were further confirmed by molecular docking in silico with binding scores of 5.450, 5.295 and 2.197 between putative HaCYP6B7 protein and bifenthrin, fenvalerate and chlorpyrifos, respectively. The results of present study provided more direct and important evidence on the role of HaCYP6B7 conferring pyrethroid resistance in H. armigera. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

The Use of F2 Screening for Detection of Resistance to Emamectin Benzoate, Chlorantraniliprole, and Indoxacarb in Australian Populations of Helicoverpa armigera (Lepidoptera: Noctuidae).

PubMed

Bird, L J; Drynan, L J; Walker, P W

2017-04-01

The ability to effectively detect changes in susceptibility to insecticides is an integral component of resistance management strategies and is highly dependent upon precision of methods deployed. Between 2013 and 2016, F2 screens were performed for detection of resistance alleles in Helicoverpa armigera (Hübner) to emamectin benzoate, chlorantraniliprole, and indoxacarb in major cropping regions of eastern Australia. Resistance to emamectin benzoate was not detected. There were low but detectable levels of survival at discriminating concentrations of chlorantraniliprole and indoxacarb. Alleles conferring an advantage to chlorantraniliprole were present at a frequency of 0.0027 (95% CI 0.0012-0.0064; n = 1,817). Alleles conferring an advantage to indoxacarb were present at a frequency of 0.027 (95% CI 0.020-0.035; n = 1,863). Complementation tests for allelism in six of seven positive indoxacarb tests indicated that resistance was due to alleles present at the same locus. The majority (88%) of lines that tested positive for indoxacarb resistance deviated from a model of recessive inheritance. Pheromone-caught male moths contributed significantly greater numbers of F2 lines compared with moths derived from field-collected eggs or larvae. There was no difference in the detectability of indoxacarb resistance in F2 lines from pheromone-caught moths compared with moths derived from immature stages collected from the field and reared to adult under laboratory conditions. Therefore, we recommend the use of pheromone traps for sourcing insects for F2 screening as a more cost- and time-efficient alternative to traditional methods of sampling. © 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.

Yeast one-hybrid screening the potential regulator of CYP6B6 overexpression of Helicoverpa armigera under 2-tridecanone stress.

PubMed

Zhao, J; Liu, X N; Li, F; Zhuang, S Z; Huang, L N; Ma, J; Gao, X W

2016-04-01

In insect, the cytochrome P450 plays a pivotal role in detoxification to toxic allelochemicals. Helicoverpa armigera can tolerate and survive in 2-tridecanone treatment owing to the CYP6B6 responsive expression, which is controlled by some regulatory DNA sequences and transcription regulators. Therefore, the 2-tridecanone responsive region and transcription regulators of the CYP6B6 are responsible for detoxification of cotton bollworm. In this study, we used yeast one-hybrid to screen two potential transcription regulators of the CYP6B6 from H. armigera that respond to the plant secondary toxicant 2-tridecanone, which were named Prey1 and Prey2, respectively. According to the NCBI database blast, Prey1 is the homology with FK506 binding protein (FKBP) of Manduca sexta and Bombyx mori that belongs to the FKBP-C superfamily, while Prey2 may be a homology of an unknown protein of Papilio or the fcaL24 protein homology of B. mori. The electrophoretic mobility shift assays revealed that the FKBP of prokaryotic expression could specifically bind to the active region of the CYP6B6 promoter. After the 6th instar larvae of H. armigera reared on 2-tridecanone artificial diet, we found there were similar patterns of CYP6B6 and FKBP expression of the cotton bollworm treated with 10 mg g-1 2-tridecanone for 48 h, which correlation coefficient was the highest (0.923). Thus, the FKBP is identified as a strong candidate for regulation of the CYP6B6 expression, when the cotton bollworm is treated with 2-tridecanone. This may lead us to a better understanding of transcriptional mechanism of CYP6B6 and provide very useful information for the pest control.

Differential immunosuppression by Campoletis chlorideae eggs and ichnovirus in larvae of Helicoverpa armigera and Spodoptera exigua.

PubMed

Han, Li-Bin; Yin, Li-Hong; Huang, Ling-Qiao; Wang, Chen-Zhu

2015-09-01

The ichneumonid wasp, Campoletis chlorideae Uchida, successfully develops in the cotton bollworm Helicoverpa armigera (Hübner), but rarely survives in the beet armyworm Spodoptera exigua (Hübner) due to the encapsulation by host immunity. In this study, we investigated the role of C. chlorideae ichnovirus (CcIV) and eggs in the evasion of the host immune system. Washed eggs of different types, immature, mature, newly laid, or pretreated with protease K, were injected alone or with the calyx fluid containing CcIV into the larvae of H. armigera and S. exigua. In H. armigera, when injected with washed eggs alone, only 9.5% of the mature eggs were encapsulated at 24h post-injection. This is much lower than that of the immature eggs (100%), mature eggs pretreated with protease K (100%) and newly laid eggs (54.4%). No encapsulation was observed when the washed eggs were co-injected with calyx fluid at 24h post-injection. Conversely, the eggs in all treatments were encapsulated in S. exigua. Electron microscopic observations of parasitoid eggs showed structural differences between the surfaces of the mature and other kinds of eggs. The injected CcIV decreased the numbers of host hemocytes and suppressed the spreading ability of plasmatocytes and granulocytes in H. armigera, but had little effect on the hemocytes from S. exigua. In conclusion, the C. chlorideae egg provides a passive protection against encapsulation by itself, and CcIV supplies an active protection through disrupting host immune responses. These coordinated protections are host-specific, implying their role in host range determination. Copyright © 2015 Elsevier Inc. All rights reserved.

Effect of cotton bollworm (Helicoverpa armigera Hübner) caused injury on maize grain content, especially regarding to the protein alteration.

PubMed

Keszthelyi, S; Pál-Fám, F; Kerepesi, I

2011-03-01

The cotton bollworm (Helicoverpa armigera Hübner), which migrated in the Carpathian-basin from Mediterraneum in the last decades, is becoming an increasingly serious problem for maize producers in Hungary. In several regions the damage it causes has reached the threshold of economic loss, especially in the case of the sweet maize cultivation. The aim of the research was to determine the changing of ears weights and in-kernel accumulation and alteration in grain as a function of cotton bollworm mastication.Our investigation confirmed that there is an in-kernel and protein pattern change of maize grain by cotton bollworm. Our results proved the significant damaging of each part of ears by cotton bollworm masticating (the average weight loss of ears: 13.99%; the average weight loss of grains: 14.03%; the average weight loss of cobs: 13.74%), with the exception of the increasing of the grain-cob ratio. Our examinations did not prove the water loss - that is the "forced maturing" - caused by the damage. Decreasing of raw fat (control: 2.8%; part-damaged: 2.6%; damaged: 2.4%) and starch content (control: 53.1%; part-damaged: 46.6%; damaged: 44.7%) were registered as a function of injury. In contrast, the raw protein content was increased (control: 4.7%; part-damaged: 5.3%; damaged: 7.4%) by maize ear masticating. The most conspicuous effect on protein composition changing was proved by comparison of damaged grain samples by SDS PAGE. Increased amounts of 114, 50, 46 and 35 kDa molecular mass proteins were detected which explained the more than 50% elevation of raw protein content. The statistical analysis of molecular weights proved the protein realignment as a function of the pest injuries, too.

Role of induced glutathione-S-transferase from Helicoverpa armigera (Lepidoptera: Noctuidae) HaGST-8 in detoxification of pesticides.

PubMed

Labade, Chaitali P; Jadhav, Abhilash R; Ahire, Mehul; Zinjarde, Smita S; Tamhane, Vaijayanti A

2018-01-01

The present study deals with glutathione-S-transferase (GST) based detoxification of pesticides in Helicoverpa armigera and its potential application in eliminating pesticides from the environment. Dietary exposure of a pesticide mixture (organophosphates - chlorpyrifos and dichlorvos, pyrethroid - cypermethrin; 2-15ppm each) to H. armigera larvae resulted in a dose dependant up-regulation of GST activity and gene expression. A variant GST from H. armigera (HaGST-8) was isolated from larvae fed with 10ppm pesticide mixture and it was recombinantly expressed in yeast (Pichia pastoris HaGST-8). HaGST-8 had a molecular mass of 29kDa and was most active at pH 9 at 30°C. GC-MS and LC-HRMS analysis validated that HaGST-8 was effective in eliminating organophosphate type of pesticides and partially reduced the cypermethrin content (53%) from aqueous solutions. Unlike the untransformed yeast, P. pastoris HaGST-8 grew efficiently in media supplemented with pesticide mixtures (200 and 400ppm each pesticide) signifying the detoxification ability of HaGST-8. The amino acid sequence of HaGST-8 and the already reported sequence of HaGST-7 had just 2 mismatches. The studies on molecular interaction strengths revealed that HaGST-8 had stronger binding affinities with organophosphate, pyrethroid, organochloride, carbamate and neonicotinoid type of pesticides. The abilities of recombinant HaGST-8 to eliminate pesticides and P. pastoris HaGST-8 to grow profusely in the presence of high level of pesticide content can be applied for removal of such residues from food, water resources and bioremediation. Copyright © 2017 Elsevier Inc. All rights reserved.

Helicoverpa zea (Lepidoptera: Noctuidae) and Spodoptera frugiperda (Lepidoptera: Noctuidae) Responses to Sorghum bicolor (Poales: Poaceae) Tissues From Lowered Lignin Lines

PubMed Central

Dowd, Patrick F.; Sattler, Scott E.

2015-01-01

The presence of lignin within biomass impedes the production of liquid fuels. Plants with altered lignin content and composition are more amenable to lignocellulosic conversion to ethanol and other biofuels but may be more susceptible to insect damage where lignin is an important resistance factor. However, reduced lignin lines of switchgrasses still retained insect resistance in prior studies. Therefore, we hypothesized that sorghum lines with lowered lignin content will also retain insect resistance. Sorghum excised leaves and stalk pith Sorghum bicolor (L.) Moench (Poales: Poaceae) from near isogenic brown midrib (bmr) 6 and 12 mutants lines, which have lowered lignin content and increased lignocellulosic ethanol conversion efficiency, were examined for insect resistance relative to wild-type (normal BTx623). Greenhouse and growth chamber grown plant tissues were fed to first-instar larvae of corn earworms, Helicoverpa zea (Boddie) and fall armyworms Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), two sorghum major pests. Younger bmr leaves had significantly greater feeding damage in some assays than wild-type leaves, but older bmr6 leaves generally had significantly less damage than wild-type leaves. Caterpillars feeding on the bmr6 leaves often weighed significantly less than those feeding on wild-type leaves, especially in the S. frugiperda assays. Larvae fed the pith from bmr stalks had significantly higher mortality compared with those larvae fed on wild-type pith, which suggested that bmr pith was more toxic. Thus, reducing lignin content or changing subunit composition of bioenergy grasses does not necessarily increase their susceptibility to insects and may result in increased resistance, which would contribute to sustainable production. PMID:25601946

Insecticidal activity of camphene, zerumbone and α-humulene from Cheilocostus speciosus rhizome essential oil against the Old-World bollworm, Helicoverpa armigera.

PubMed

Benelli, Giovanni; Govindarajan, Marimuthu; Rajeswary, Mohan; Vaseeharan, Baskaralingam; Alyahya, Sami A; Alharbi, Naiyf S; Kadaikunnan, Shine; Khaled, Jamal M; Maggi, Filippo

2018-02-01

The fast-growing resistance development to several synthetic and microbial insecticides currently marketed highlighted the pressing need to develop novel and eco-friendly pesticides. Among the latter, botanical ones are attracting high research interest due to their multiple mechanisms of action and reduced toxicity on non-target vertebrates. Helicoverpa armigera (Lepidoptera: Noctuidae) is a key polyphagous insect pest showing insecticide resistance to several synthetic molecules used for its control. Therefore, here we focused on the rhizome essential oil extracted from an overlooked Asian plant species, Cheilocostus speciosus (J. Konig) C. Specht (Costaceae), as a source of compounds showing ingestion toxicity against H. armigera third instar larvae, as well as ovicidal toxicity. In acute larvicidal assays conducted after 24h, the C. speciosus essential oil achieved a LC 50 value of 207.45µg/ml. GC and GC-MS analyses highlighted the presence of zerumbone (38.6%), α-humulene (14.5%) and camphene (9.3%) as the major compounds of the oil. Ingestion toxicity tests carried out testing these pure molecules showed LC 50 values of 10.64, 17.16 and 20.86µg/ml, for camphene, zerumbone and α-humulene, respectively. Moreover, EC 50 values calculated on H. armigera eggs were 35.39, 59.51 and 77.10µg/ml for camphene, zerumbone and α-humulene, respectively. Overall, this study represents the first report on the toxicity of C. speciosus essential oil against insect pests of agricultural and medical veterinary importance, highlighting that camphene, zerumbone and α-humulene have a promising potential as eco-friendly botanical insecticides. Copyright © 2017 Elsevier Inc. All rights reserved.

Determinant Factors in the Production of a Co-Occluded Binary Mixture of Helicoverpa armigera Alphabaculovirus (HearNPV) Genotypes with Desirable Insecticidal Characteristics.

PubMed

Arrizubieta, Maite; Simón, Oihane; Williams, Trevor; Caballero, Primitivo

2016-01-01

A co-occluded binary mixture of Helicoverpa armigera nucleopolyhedrovirus genotypes HearSP1B and HearLB6 at a 1:1 ratio (HearSP1B+HearLB6) was selected for the development of a virus-based biological insecticide, which requires an efficient large-scale production system. In vivo production systems require optimization studies in each host-virus pathosystem. In the present study, the effects of larval instar, rearing density, timing of inoculation, inoculum concentration and temperature on the production of HearSP1B+HearLB6 in its homologous host were evaluated. The high prevalence of cannibalism in infected larvae (40-87%) indicated that insects require individual rearing to avoid major losses in OB production. The OB production of recently molted fifth instars (7.0 x 109 OBs/larva), combined with a high prevalence of mortality (85.7%), resulted in the highest overall OB yield (6.0 x 1011 OBs/100 inoculated larvae), compared to those of third or fourth instars. However, as inoculum concentration did not influence final OB yield, the lowest concentration, LC80 (5.5 x 106 OBs/ml), was selected. Incubation temperature did not significantly influence OB yield, although larvae maintained at 30°C died 13 and 34 hours earlier than those incubated at 26°C and 23°C, respectively. We conclude that the efficient production of HearSP1B+HearLB6 OBs involves inoculation of recently molted fifth instars with a LC80 concentration of OBs followed by individual rearing at 30°C.

Activity of Selected Formulated Biorational and Synthetic Insecticides Against Larvae of Helicoverpa armigera (Lepidoptera: Noctuidae).

PubMed

Vivan, L M; Torres, J B; Fernandes, P L S

2017-02-01

This work studied 17 insecticides belonging to nucleopolyhedrovirus (NPV), Bacillus thuringiensis (Bt kurstaki and Bt aizawai), benzoylureas (insect growth regulators [IGRs]), carbamates, organophosphates, spinosyns, and diamides against larvae of Helicoverpa armigera (Hübner), invasive species in the South American continent. Larvae of different instars were fed for 7 d with untreated or insecticide-treated diets. Mortality was recorded daily for 7 d, and surviving larvae were individually weighed on the seventh day. The NPV and Bt insecticides caused 100% mortality of first-instar larvae and first-instar and second-instar larvae, respectively. However, both NPV and Bt-based products caused low mortality of third-instar larvae and did not kill older larvae. The IGR lufenuron was highly effective against all three ages of larvae tested, whereas teflubenzuron and triflumuron produced maximum 60% mortality of second-instar larvae and lower than 50% to older larvae. Thiodicarb, chlorantraniliprole, indoxacarb, chlorpyrifos, and chlorfenapyr, irrespective of tested age, caused 100% mortality of larvae, with the last two insecticides reaching 100% mortality within 2 d of feeding on the treated diet. Flubendiamide caused lower mortality but significantly affected the weight of surviving larvae, whereas neither spinosad nor methomyl produced significant mortality or affected the weight of larvae. Based on the results, the age of H. armigera larvae plays an important role in the recommendation of NPV and Bt insecticides. Furthermore, there are potential options between biological and synthetic insecticides tested against H. armigera, and recording larval size during monitoring, in addition to the infestation level, should be considered when recommending biological-based insecticides to control this pest. © 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.

The movement and distribution of Helicoverpa armigera (Hübner) larvae on pea plants is affected by egg placement and flowering.

PubMed

Perkins, L E; Cribb, B W; Hanan, J; Zalucki, M P

2010-10-01

The distribution and movement of 1st instar Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) larvae on whole garden pea (Pisum sativum L.) plants were determined in glasshouse trials. This economically-important herbivore attacks a wide variety of agricultural, horticultural and indigenous plants. To investigate the mechanisms underlying larval intra-plant movement, we used early-flowering and wild-type plant genotypes and placed eggs at different vertical heights within the plants, one egg per plant. Leaf water and nitrogen content and cuticle hardness were measured at the different plant heights. Of 92 individual larvae, 41% did not move from the node of eclosion, 49% moved upwards and 10% moved downwards with the distance moved being between zero and ten plant nodes. Larvae from eggs placed on the lower third of the plant left the natal leaf more often and moved further than larvae from eggs placed in the middle or upper thirds. The low nutritive value of leaves was the most likely explanation for more movement away from lower plant regions. Although larvae on flowering plants did not move further up or down than larvae on non-flowering plants, they more often departed the leaflet (within a leaf) where they eclosed. The final distribution of larvae was affected by plant genotype, with larvae on flowering plants found less often on leaflets and more often on stipules, tendrils and reproductive structures. Understanding intra-plant movement by herbivorous insects under natural conditions is important because such movement determines the value of economic loss to host crops. Knowing the behaviour underlying the spatial distribution of herbivores on plants will assist us to interpret field data and should lead to better informed pest management decisions.

RNAi of selected candidate genes interrupts growth and development of Helicoverpa armigera.

PubMed

Chikate, Yojana R; Dawkar, Vishal V; Barbole, Ranjit S; Tilak, Priyadarshini V; Gupta, Vidya S; Giri, Ashok P

2016-10-01

Helicoverpa armigera is one of the major crop pests and is less amenable to current pest control approaches. RNA interference (RNAi) is emerging as a potent arsenal for the insect pest control over current methods. Here, we examined the effect on growth and development in H. armigera by targeting various enzymes/proteins such as proteases like trypsins (HaTry2, 3, 4 and 6), chymotrypsin (HaChy4) and cysteine protease like cathepsin (HaCATHL); glutathione S-transferases (HaGST1a, 6 and 8); esterases (HaAce4, HaJHE); catalase (HaCAT); super-oxide-dismutase (HaCu/ZnSOD); fatty acid binding protein (HaFabp) and chitin deacetylase (HaCda5b) through dsRNA approach. Significant downregulation of cognate mRNA expression and reduced activity of trypsin and GST-like enzyme were evident upon feeding candidate dsRNAs to the larvae. Among these, the highest mortality was observed in HaAce4 dsRNA fed larvae followed by HaJHE; HaCAT; HaCuZnSOD; HaFabp and HaTry3 whereas remaining ones showed relatively lower mortality. Furthermore, the dsRNA fed larvae showed significant reduction in the larval mass and abnormalities at the different stages of H. armigera development compared to their control diets. For example, malformed larvae, pupae and moth at a dose of 60μg/day were evident in high number of individual insects fed on dsRNA containing diets. Moreover, the growth and development of insects and moths were retarded in dsRNA fed larvae. These findings might provide potential new candidates for designing effective dsRNA as pesticide in crop protection. Copyright © 2016 Elsevier B.V. All rights reserved.

Identification of MicroRNAs in Helicoverpa armigera and Spodoptera litura Based on Deep Sequencing and Homology Analysis

PubMed Central

Ge, Xie; Zhang, Yong; Jiang, Jianhao; Zhong, Yi; Yang, Xiaonan; Li, Zhiqian; Huang, Yongping; Tan, Anjiang

2013-01-01

The current identification of microRNAs (miRNAs) in insects is largely dependent on genome sequences. However, the lack of available genome sequences inhibits the identification of miRNAs in various insect species. In this study, we used a miRNA database of the silkworm Bombyx mori as a reference to identify miRNAs in Helicoverpa armigera and Spodoptera litura using deep sequencing and homology analysis. Because all three species belong to the Lepidoptera, the experiment produced reliable results. Our study identified 97 and 91 conserved miRNAs in H. armigera and S. litura, respectively. Using the genome of B. mori and BAC sequences of H. armigera as references, 1 novel miRNA and 8 novel miRNA candidates were identified in H. armigera, and 4 novel miRNA candidates were identified in S. litura. An evolutionary analysis revealed that most of the identified miRNAs were insect-specific, and more than 20 miRNAs were Lepidoptera-specific. The investigation of the expression patterns of miR-2a, miR-34, miR-2796-3p and miR-11 revealed their potential roles in insect development. miRNA target prediction revealed that conserved miRNA target sites exist in various genes in the 3 species. Conserved miRNA target sites for the Hsp90 gene among the 3 species were validated in the mammalian 293T cell line using a dual-luciferase reporter assay. Our study provides a new approach with which to identify miRNAs in insects lacking genome information and contributes to the functional analysis of insect miRNAs. PMID:23289012

Recovery of infectious pariacoto virus from cDNA clones and identification of susceptible cell lines.

PubMed

Johnson, K N; Ball, L A

2001-12-01

Pariacoto virus (PaV) is a nodavirus that was recently isolated in Peru from the Southern armyworm, Spodoptera eridania. Virus particles are non enveloped and about 30 nm in diameter and have T=3 icosahedral symmetry. The 3.0-A crystal structure shows that about 35% of the genomic RNA is icosahedrally ordered, with the RNA forming a dodecahedral cage of 25-nucleotide (nt) duplexes that underlie the inner surface of the capsid. The PaV genome comprises two single-stranded, positive-sense RNAs: RNA1 (3,011 nt), which encodes the 108-kDa catalytic subunit of the RNA-dependent RNA polymerase, and RNA2 (1,311 nt), which encodes the 43-kDa capsid protein precursor alpha. In order to apply molecular genetics to the structure and assembly of PaV, we identified susceptible cell lines and developed a reverse genetic system for this virus. Cell lines that were susceptible to infection by PaV included those from Spodoptera exigua, Helicoverpa zea and Aedes albopictus, whereas cells from Drosophila melanogaster and Spodoptera frugiperda were refractory to infection. To recover virus from molecular clones, full-length cDNAs of PaV RNAs 1 and 2 were cotranscribed by T7 RNA polymerase in baby hamster kidney cells that expressed T7 RNA polymerase. Lysates of these cells were infectious both for cultured cells from Helicoverpa zea (corn earworm) and for larvae of Galleria mellonella (greater wax moth). The combination of infectious cDNA clones, cell culture infectivity, and the ability to produce milligram amounts of virus allows the application of DNA-based genetic methods to the study of PaV structure and assembly.

A Novel Binary Mixture of Helicoverpa armigera Single Nucleopolyhedrovirus Genotypic Variants Has Improved Insecticidal Characteristics for Control of Cotton Bollworms

PubMed Central

Arrizubieta, Maite; Simón, Oihane; Williams, Trevor

2015-01-01

The genotypic diversity of two Spanish isolates of Helicoverpa armigera single nucleopolyhedrovirus (HearSNPV) was evaluated with the aim of identifying mixtures of genotypes with improved insecticidal characteristics for control of the cotton bollworm. Two genotypic variants, HearSP1A and HearSP1B, were cloned in vitro from the most pathogenic wild-type isolate of the Iberian Peninsula, HearSNPV-SP1 (HearSP1-wt). Similarly, six genotypic variants (HearLB1 to -6) were obtained by endpoint dilution from larvae collected from cotton crops in southern Spain that died from virus disease during laboratory rearing. Variants differed significantly in their insecticidal properties, pathogenicity, speed of kill, and occlusion body (OB) production (OBs/larva). HearSP1B was ∼3-fold more pathogenic than HearSP1-wt and the other variants. HearLB1, HearLB2, HeaLB5, and HearLB6 were the fastest-killing variants. Moreover, although highly virulent, HearLB1, HearLB4, and HearLB5 produced more OBs/larva than did the other variants. The co-occluded HearSP1B:LB6 mixture at a 1:1 proportion was 1.7- to 2.8-fold more pathogenic than any single variant and other mixtures tested and also killed larvae as fast as the most virulent genotypes. Serial passage resulted in modified proportions of the component variants of the HearSP1B:LB6 co-occluded mixture, suggesting that transmissibility could be further improved by this process. We conclude that the improved insecticidal phenotype of the HearSP1B:LB6 co-occluded mixture underlines the utility of the genotypic variant dissection and reassociation approach for the development of effective virus-based insecticides. PMID:25841011

Determinant Factors in the Production of a Co-Occluded Binary Mixture of Helicoverpa armigera Alphabaculovirus (HearNPV) Genotypes with Desirable Insecticidal Characteristics

PubMed Central

Arrizubieta, Maite; Simón, Oihane; Williams, Trevor; Caballero, Primitivo

2016-01-01

A co-occluded binary mixture of Helicoverpa armigera nucleopolyhedrovirus genotypes HearSP1B and HearLB6 at a 1:1 ratio (HearSP1B+HearLB6) was selected for the development of a virus-based biological insecticide, which requires an efficient large-scale production system. In vivo production systems require optimization studies in each host-virus pathosystem. In the present study, the effects of larval instar, rearing density, timing of inoculation, inoculum concentration and temperature on the production of HearSP1B+HearLB6 in its homologous host were evaluated. The high prevalence of cannibalism in infected larvae (40–87%) indicated that insects require individual rearing to avoid major losses in OB production. The OB production of recently molted fifth instars (7.0 x 109 OBs/larva), combined with a high prevalence of mortality (85.7%), resulted in the highest overall OB yield (6.0 x 1011 OBs/100 inoculated larvae), compared to those of third or fourth instars. However, as inoculum concentration did not influence final OB yield, the lowest concentration, LC80 (5.5 x 106 OBs/ml), was selected. Incubation temperature did not significantly influence OB yield, although larvae maintained at 30°C died 13 and 34 hours earlier than those incubated at 26°C and 23°C, respectively. We conclude that the efficient production of HearSP1B+HearLB6 OBs involves inoculation of recently molted fifth instars with a LC80 concentration of OBs followed by individual rearing at 30°C. PMID:27732657

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.

Purification and Partial Characterization of Trypsin-Specific Proteinase Inhibitors from Pigeonpea Wild Relative Cajanus platycarpus L. (Fabaceae) Active against Gut Proteases of Lepidopteran Pest Helicoverpa armigera

PubMed Central

Swathi, Marri; Mishra, Prashant K.; Lokya, Vadthya; Swaroop, Vanka; Mallikarjuna, Nalini; Dutta-Gupta, Aparna; Padmasree, Kollipara

2016-01-01

Proteinase inhibitors (PIs) are natural defense proteins of plants found to be active against gut proteases of various insects. A pigeonpea wild relative Cajanus platycarpus was identified as a source of resistance against Helicoverpa armigera, a most devastating pest of several crops including pigeonpea. In the light of earlier studies, trypsin-specific PIs (CpPI 63) were purified from mature dry seeds of C. platycarpus (ICPW-63) and characterized their biochemical properties in contributing to H. armigera resistance. CpPI 63 possessed significant H. armigera gut trypsin-like proteinase inhibitor (HGPI) activity than trypsin inhibitor (TI) activity. Analysis of CpPI 63 using two-dimensional (2-D) electrophoresis and matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry revealed that it contained several isoinhibitors and small oligomers with masses ranging between 6 and 58 kDa. The gelatin activity staining studies suggest that these isoinhibitors and oligomers possessed strong inhibitory activity against H. armigera gut trypsin-like proteases (HGPs). The N-terminal sequence of the isoinhibitors (pI 6.6 and pI 5.6) of CpPI 63 exhibited 80% homology with several Kunitz trypsin inhibitors (KTIs) as well as miraculin-like proteins (MLPs). Further, modification of lysine residue(s) lead to 80% loss in both TI and HGPI activities of CpPI 63. In contrast, the TI and HGPI activities of CpPI 63 were stable over a wide range of temperature and pH conditions. The reported results provide a biochemical basis for pod borer resistance in C. platycarpus. PMID:27656149

Cloning and characterization of the pheromone biosynthesis activating neuropeptide receptor gene in Spodoptera littoralis larvae.

PubMed

Zheng, Lei; Lytle, Christian; Njauw, Ching-Ni; Altstein, Miriam; Martins-Green, Manuela

2007-05-15

In noctuid moths cuticular pigmentation is regulated by the pyrokinin/pheromone biosynthesis activating neuropeptide (PK/PBAN) family, which also mediates a variety of other functions in moths and other insects. Numerous studies have shown that these neuropeptides exert their functions through activation of the PBAN receptor (PBAN-R), with subsequent Ca(2+) influx, followed by either activation of cAMP or direct activation of downstream kinases. Recently, several PBAN-Rs have been identified, all of which are from the pheromone gland of adult female moths, but evidence shows that functional PK/PBAN-Rs can also be expressed in insect larvae, where they mediate melanization and possibly other functions (e.g., diapause). Here, we identified a gene encoding a G-protein-coupled receptor from the 5th instar larval tissue of the moth Spodoptera littoralis. The cDNA of this gene contains an open reading frame with a length of 1050 nucleotides, which translates to a 350-amino acid, 42-kDa protein that shares 92% amino acid identity with Helicoverpa zea and Helicoverpa armigera PBAN-R, 81% with Bombyx mori PBAN-R and 72% with Plutella xylostella PBAN-R. The S. littoralis PBAN-R gene was stably expressed in NIH3T3 cells and transiently in HEK293 cells. We show that it mediates the dose-dependent PBAN-induced intracellular Ca(2+) response and activation of the MAP kinase via a PKC-dependent but Galphai-independent signaling mechanism. Other PK/PBAN family peptides (pheromonotropin and a C-terminally PBAN-derived peptide PBAN(28-33)NH(2)) also triggered MAP kinase activation. This receptor, together with the previously cloned PBAN-R, may facilitate our understanding of the cell-specific responses and functional diversities of this diverse neuropeptide family.

Characterization of a digestive carboxypeptidase from the insect pest corn earworm (Helicoverpa armigera) with novel specificity towards C-terminal glutamate residues.

PubMed

Bown, David P; Gatehouse, John A

2004-05-01

Carboxypeptidases were purified from guts of larvae of corn earworm (Helicoverpa armigera), a lepidopteran crop pest, by affinity chromatography on immobilized potato carboxypeptidase inhibitor, and characterized by N-terminal sequencing. A larval gut cDNA library was screened using probes based on these protein sequences. cDNA HaCA42 encoded a carboxypeptidase with sequence similarity to enzymes of clan MC [Barrett, A. J., Rawlings, N. D. & Woessner, J. F. (1998) Handbook of Proteolytic Enzymes. Academic Press, London.], but with a novel predicted specificity towards C-terminal acidic residues. This carboxypeptidase was expressed as a recombinant proprotein in the yeast Pichia pastoris. The expressed protein could be activated by treatment with bovine trypsin; degradation of bound pro-region, rather than cleavage of pro-region from mature protein, was the rate-limiting step in activation. Activated HaCA42 carboxypeptidase hydrolysed a synthetic substrate for glutamate carboxypeptidases (FAEE, C-terminal Glu), but did not hydrolyse substrates for carboxypeptidase A or B (FAPP or FAAK, C-terminal Phe or Lys) or methotrexate, cleaved by clan MH glutamate carboxypeptidases. The enzyme was highly specific for C-terminal glutamate in peptide substrates, with slow hydrolysis of C-terminal aspartate also observed. Glutamate carboxypeptidase activity was present in larval gut extract from H. armigera. The HaCA42 protein is the first glutamate-specific metallocarboxypeptidase from clan MC to be identified and characterized. The genome of Drosophila melanogaster contains genes encoding enzymes with similar sequences and predicted specificity, and a cDNA encoding a similar enzyme has been isolated from gut tissue in tsetse fly. We suggest that digestive carboxypeptidases with sequence similarity to the classical mammalian enzymes, but with specificity towards C-terminal glutamate, are widely distributed in insects.

The expression of proteins involved in digestion and detoxification are regulated in Helicoverpa armigera to cope up with chlorpyrifos insecticide.

PubMed

Dawkar, Vishal V; Chikate, Yojana R; More, Tushar H; Gupta, Vidya S; Giri, Ashok P

2016-02-01

Helicoverpa armigera is a key pest in many vital crops, which is mainly controlled by chemical strategies. To manage this pest is becoming challenging due to its ability and evolution of resistance against insecticides. Further, its subsequent spread on nonhost plant is remarkable in recent times. Hence, decoding resistance mechanism against phytochemicals and synthetic insecticides is a major challenge. The present work describes that the digestion, defense and immunity related enzymes are associated with chlorpyrifos resistance in H. armigera. Proteomic analysis of H. armigera gut tissue upon feeding on chlorpyrifos containing diet (CH) and artificial diet (AD) using nano-liquid chromatography-mass spectrometry identified upregulated 23-proteins in CH fed larvae. Database searches combined with gene ontology analysis revealed that the identified gut proteins engrossed in digestion, proteins crucial for immunity, adaptive responses to stress, and detoxification. Biochemical and quantitative real-time polymerase chain reaction analysis of candidate proteins indicated that insects were struggling to get nutrients and energy in presence of CH, while at the same time endeavoring to metabolize chlorpyrifos. Moreover, we proposed a potential processing pathway of chlorpyrifos in H. armigera gut by examining the metabolites using gas chromatography-mass spectrometry. H. armigera exhibit a range of intriguing behavioral, morphological adaptations and resistance to insecticides by regulating expression of proteins involved in digestion and detoxification mechanisms to cope up with chlorpyrifos. In these contexts, as gut is a rich repository of biological information; profound analysis of gut tissues can give clues of detoxification and resistance mechanism in insects. © 2014 Institute of Zoology, Chinese Academy of Sciences.

A Generalist Herbivore Copes with Specialized Plant Defence: the Effects of Induction and Feeding by Helicoverpa armigera (Lepidoptera: Noctuidae) Larvae on Intact Arabidopsis thaliana (Brassicales) Plants.

PubMed

Zalucki, M P; Zalucki, J M; Perkins, L E; Schramm, K; Vassão, D G; Gershenzon, J; Heckel, D G

2017-06-01

Plants of the Brassicaceae are defended from feeding by generalist insects by constitutively-expressed and herbivory-induced glucosinolates (GS). We induced Arabidopsis plants 1, 16 and 24 h prior to allowing neonate larvae of the generalist Helicoverpa armigera to feed on whole plants for 72 h. These plants were subsequently retested with another group of neonates for a further 72 h. We used wild-type A. thaliana Col-0, and mutant lines lacking indolic GS, aliphatic GS or all GS. We hypothesized that larvae would not grow well on defended plants (WT) compared to those lacking GS, and would not grow well if plants had been primed or fed on for longer, due to the expected induced GS. There was survivorship on all lines suggesting H. armigera is a suitable generalist for these experiments. Larvae performed less well on wild-type and no indolic lines than on no aliphatic and no GS lines. Larvae distributed feeding damage extensively in all lines, more so on wild type and no-indolic lines. Contrary to expectations, larvae grew better on plants that had been induced for 1 to 16 h than on un-induced plants suggesting they moved to and selected less toxic plant parts within a heterogeneously defended plant. Performance declined on all lines if plants had been induced for 24 h, or had been fed upon for a further 72 h. However, contrary to expectation, individual and total GS did not increase after these two treatments. This suggests that Arabidopsis plants induce additional (not GS) defenses after longer induction periods.

A droplet digital PCR (ddPCR) assay to detect Helicoverpa armigera (Lepidoptera: Noctuidae) in bulk trap samples.

PubMed

Zink, Frida A; Tembrock, Luke R; Timm, Alicia E; Farris, Roxanne E; Perera, Omaththage P; Gilligan, Todd M

2017-01-01

Moths in the genus Helicoverpa are some of the most important agricultural pests in the world. Two species, H. armigera (Hübner) and H. zea (Boddie), cause the majority of damage to crops and millions of dollars are spent annually on control of these pests. The recent introduction of H. armigera into the New World has prompted extensive survey efforts for this species in the United States. Surveys are conducted using bucket traps baited with H. armigera pheromone, and, because the same pheromone compounds attract both species, these traps often capture large numbers of the native H. zea. Adult H. armigera and H. zea are very similar and can only be separated morphologically by minor differences in the genitalia. Thus, a time consuming genitalic dissection by a trained specialist is necessary to reliably identify either species, and every specimen must be dissected. Several molecular methods are available for differentiating and identifying H. armigera and H. zea, including two recently developed rapid protocols using real-time PCR. However, none of the published methods are capable of screening specimens in large batches. Here we detail a droplet digital PCR (ddPCR) assay that is capable of detecting a single H. armigera in a background of up to 999 H. zea. The assay has been tested using bulk extractions of 1,000 legs from actual trap samples and is effective even when using poor quality samples. This study provides an efficient, rapid, reproducible, and scalable method for processing H. armigera survey trap samples in the U.S. and demonstrates the potential for applying ddPCR technology to screen and diagnose invasive species.

Susceptibility of Helicoverpa zea (Lepidoptera: Noctuidae) Neonates to Diamide Insecticides in the Midsouthern and Southeastern United States.

PubMed

Adams, A; Gore, J; Catchot, A; Musser, F; Cook, D; Krishnan, N; Irby, T

2016-10-01

Corn earworm, Helicoverpa zea (Boddie), is a significant pest of agroecosystems in the midsouthern and southeastern regions of the United States. These insects have developed resistance to, or inconsistent control has occurred with, most insecticide classes. With their unique mode of action, insecticides in the diamide class have become a key component in management of agriculturally important lepidopteran pests. In this study, field populations of H. zea were collected in the southern United States and compared to susceptible laboratory colonies to generate baseline concentration-mortality data. LC50 and LC90 values were generated for flubendiamide and chlorantraniliprole using neonates. To achieve equivalent levels of mortality, a higher concentration of flubendiamide was required compared to chlorantraniliprole. Flubendiamide LC50 values for H. zea ranged from 16.45 to 30.74 ng/ml, with a mean of 23.53 ng/ml. Chlorantraniliprole LC50 values for H. zea ranged from 2.94 to 4.22 ng/ml, with a mean of 3.66 ng/ml. Significant differences were observed for some field populations relative to the laboratory colony. For flubendiamide, five populations had greater LC50 values and two populations had lower LC50 values compared to the laboratory colony. For chlorantraniliprole, three populations had greater LC50 values and three populations had lower LC50 values compared to the laboratory colony. The response of these populations most likely represents natural variability among populations and does not indicate a significant shift in susceptibility of this species. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America.

Diversity and prevalence of hemoparasites of wading birds in southern Florida, USA.

PubMed

Coker, Sarah M; Hernandez, Sonia M; Kistler, Whitney M; Curry, Shannon E; Welch, Catharine N; Barron, Heather W; Harsch, Stefan; Murray, Maureen H; Yabsley, Michael J

2017-12-01

Relatively few studies on hemoparasites have been conducted on wading birds in the families Ardeidae and Threskiornithidae (order Pelecaniformes), especially in the United States. In this study, we obtained baseline data on the prevalence and genetic diversity of haemosporidian parasites in wading birds opportunistically sampled from southern Florida, USA. We detected blood parasites in White Ibis ( Eudocimus albus ), Glossy Ibis ( Plegadis falcinellus ), Green Heron ( Butorides virescens ), and Roseate Spoonbill ( Platalea ajaja ) with several novel host-parasite relationships. Infected birds had low parasitemias (average 0.77%, range 0-4%) suggesting that infections were chronic. Despite the low sample sizes for several of our sampled species, these data highlight the diversity of parasites in this understudied group of birds and suggest that additional studies are needed to investigate the potential impacts of these parasites on their health, especially since southern Florida is becoming increasingly urbanized which can alter parasite transmission or host susceptibility.

Molecular identification of the fish fauna from the pantanal flood plain area in Brazil.

PubMed

Shimabukuro-Dias, Cristiane Kioko; Costa Silva, Guilherme José da; Ashikaga, Fernando Yuldi; Foresti, Fausto; Oliveira, Claudio

2017-07-01

The Pantanal is under the influence of the Paraguay River flood regime is considered to be one of the largest wetlands of the world, and has rich biodiversity, including fishes. Until now, the identification of fish species in this biome has only considered the morphological characteristics of individuals, and the present work aimed to identify the fish species of the Pantanal region through the DNA barcode methodology for investigating the biodiversity in this region. The genetic analysis of 638 samples via the GMYC approach identified 137 operational taxonomic units (OTUs) belonging to 127 species that have previously been described according to their morphological characteristics. Data suggest that 10 cases of morphospecies (Eigenmannia trileneata, E. virescens, Pimelodella gracilis, Brachyhypopomus pinnicaudatus, Brachyhypopomus sp., Ancistrus sp., Hyphessobrycon eques, Jupiaba acanthogaster, and Serrapinnus calliurus) represent complexes of cryptic species, and the number of species described in the Pantanal region has thus potentially been underestimated.

Cucullanus maldivensis n. sp. (Nematoda: Cucullanidae) and some other adult nematodes from marine fishes off the Maldive Islands.

PubMed

Moravec, Frantisek; Lorber, Julia; Konecný, Robert

2008-05-01

Marine fishes were collected from off the Maldive Islands in March, 2005. From amongst the material collected, the nematode Cucullanus maldivensis n. sp. is described from the intestine of a lutjanid fish, the black and white snapper Macolor niger (Forsskål). This species is morphologically and biometrically most similar to C. bourdini Petter & Le Bel, 1992, differing from it principally in the protruding vulval lips, the location of the first pair of pre-anal papillae, the absence of an elevated cloacal region, and having distinctly larger eggs (51-57 x 33-36 microm). Additionally, adult females of the nematodes Procamallanus (Spirocamallanus) sp. and Camallanus sp. from the green jobfish Aprion virescens Valenciennes (Lutjanidae) and the rainbow runner Elegatis bipinnulata (Quoy & Gaimard) (Carangidae), respectively, were collected. These camallanids are illustrated and measurements are provided, but they were not identified or described in detail as no males were collected.

Tissue localization and partial characterization of pheromone biosynthesis activating neuropeptide in Achaea janata.

PubMed

Ajitha, V S; Muraleedharan, D

2005-03-01

Female sex pheromone production in certain moth species have been shown to be regulated by a cephalic endocrine peptidic factor: pheromone biosynthesis activating neuropeptide (PBAN), having 33 amino acid residues. Antisera against synthetic Heliothis zea-PBAN were developed. Using these polyclonals, immunoreactivity was mapped in the nervous system of Achaea janata. Three distinct groups of immunopositive secretory neurons were identified in the suboesophageal ganglion; and immunoreactivity was observed in the corpora cardiaca, thoracic and in the abdominal ganglia. From about 6000 brain sub-oesophageal ganglion complexes, the neuropeptide was isolated; and purified sequentially by Sep-pak and reversed phase high performance liquid chromatographic methods. Identity of purified PBAN fraction was confirmed with polyclonal antibody by immunoblotting. Molecular mass of the isolated peptide was determined by matrix-assisted laser desorption/ionization mass spectrometry, and was found to be 3900 Da, same as that of known H. zea-PBAN. Radiochemical bioassay confirmed the pheromonotropic effect of the isolated neuropeptide in this insect.

Variation in P450-mediated fenvalerate resistance levels is not correlated with CYP337B3 genotype in Chinese populations of Helicoverpa armigera.

PubMed

Han, Yangchun; Yu, Wanting; Zhang, Weiqing; Yang, Yihua; Walsh, Tom; Oakeshott, John G; Wu, Yidong

2015-06-01

Metabolic resistance to synthetic pyrethroids in Helicoverpa   armigera has recently been associated with the chimeric cytochrome P450 enyzme CYP337B3. One variant of the latter, CYP337B3v1, accounts for 40-50 fold resistance to fenvalerate in an Australian population while a second variant, CYP337B3v2, has been associated with ~7 fold resistance to cypermethrin in a Pakistani population. Here we show that ~250-1200 fold resistance to fenvalerate in populations of the species from northern and northwestern China is largely due to P450-based metabolism, and that CYP337B3v2 is also at high frequency in these populations but absent in a susceptible control strain. However we find little correlation between the level of resistance and CYP337B3v2 frequency, either across the resistant populations studied, or over time within them. While there is variation between populations in the levels of CYP337B3v2 expression, this is not correlated with the level of resistance either. These data suggest that much of the variation in the level of fenvalerate resistance in China is explained by P450s other than CYP337B3. We also find that both the level of resistance and CYP337B3v2 frequency decline in field populations transferred to the laboratory and remained there without fenvalerate exposure, suggesting a fitness cost to both characters in the absence of the pesticide pressure. However the declines in the two characters are not well correlated across populations, again consistent with a large contribution to the variation in resistance levels from factors other than CYP337B3. Copyright © 2014 Elsevier Inc. All rights reserved.

An independent occurrence of the chimeric P450 enzyme CYP337B3 of Helicoverpa armigera confers cypermethrin resistance in Pakistan.

PubMed

Rasool, Akhtar; Joußen, Nicole; Lorenz, Sybille; Ellinger, Renate; Schneider, Bernd; Khan, Sher Afzal; Ashfaq, Muhammad; Heckel, David G

2014-10-01

The increasing resistance level of insect pest species is a major concern to agriculture worldwide. The cotton bollworm, Helicoverpa armigera, is one of the most important pest species due to being highly polyphagous, geographically widespread, and resistant towards many chemical classes of insecticides. We previously described the mechanism of fenvalerate resistance in Australian populations conferred by the chimeric cytochrome P450 monooxygenase CYP337B3, which arose by unequal crossing-over between CYP337B1 and CYP337B2. Here, we show that this mechanism is also present in the cypermethrin-resistant FSD strain from Pakistan. The Pakistani and the Australian CYP337B3 alleles differ by 18 synonymous and three nonsynonymous SNPs and additionally in the length and sequence of the intron. Nevertheless, the activity of both CYP337B3 proteins is comparable. We demonstrate that CYP337B3 is capable of metabolizing cypermethrin (trans- and especially cis-isomers) to the main metabolite 4'-hydroxycypermethrin, which exhibits no intrinsic toxicity towards susceptible larvae. In a bioassay, CYP337B3 confers a 7-fold resistance towards cypermethrin in FSD larvae compared to susceptible larvae from the Australian TWB strain lacking CYP337B3. Linkage analysis shows that presence of CYP337B3 accounts for most of the cypermethrin resistance in the FSD strain; up-regulation of other P450s in FSD plays no detectable role in resistance. The presence or absence of CYP337B3 can be easily detected by a simple PCR screen, providing a powerful tool to rapidly distinguish resistant from susceptible individuals in the field and to determine the geographical distribution of this resistance gene. Our results suggest that CYP337B3 evolved twice independently by unequal crossing-over between CYP337B2 and two different CYP337B1 alleles. Copyright © 2014 Elsevier Ltd. All rights reserved.

Over-expression of multiple cytochrome P450 genes in fenvalerate-resistant field strains of Helicoverpa armigera from north of China.

PubMed

Xu, Li; Li, Dongzhi; Qin, Jianying; Zhao, Weisong; Qiu, Lihong

2016-09-01

Pyrethroid resistance was one of the main reasons for control failure of cotton bollworm Helicoverpa armigera (Hübner) in China. The promotion of Bt crops decreased the application of chemical insecticides in controlling H.armigera. However, the cotton bollworm still kept high levels of resistance to fenvalerate. In this study, the resistance levels of 8 field-collected strains of H. armigera from north of China to 4 insecticides, as well as the expression levels of related P450 genes were investigated. The results of bioassay indicated that the resistance levels to fenvalerate in the field strains varied from 5.4- to 114.7-fold, while the resistance levels to lambda-cyhalothrin, phoxim and methomyl were low, which were ranged from 1.5- to 5.2-, 0.2- to 1.6-, and 2.9- to 8.3- fold, respectively, compared to a susceptible strain. Synergistic experiment showed that PBO was the most effective synergist in increasing the sensitivity of H. armigera to fenvalerate, suggesting that P450 enzymes were involved in the pyrethroid resistance in the field strains. The results of quantitative RT-PCR indicated that eight P450 genes (CYP332A1, CYP4L11, CYP4L5, CYP4M6, CYP4M7, CYP6B7, CYP9A12, CYP9A14) were all significantly overexpressed in Hejian1 and Xiajin1 strains of H. armigera collected in 2013, and CYP4L5 was significantly overexpressed in all the 6 field strains collected in 2014. CYP332A1, CYP6B7 and CYP9A12 had very high overexpression levels in all the field strains, indicating their important roles in fenvalerate resistance. The results suggested that multiple P450 genes were involved in the high-level fenvalerate-resistance in different field strains of H. armigera collected from north of China. Copyright © 2016 Elsevier B.V. All rights reserved.

Genomic sequencing and analyses of HearMNPV—a new Multinucleocapsid nucleopolyhedrovirus isolated from Helicoverpa armigera

PubMed Central

2012-01-01

Background HearMNPV, a nucleopolyhedrovirus (NPV), which infects the cotton bollworm, Helicoverpa armigera, comprises multiple rod-shaped nucleocapsids in virion(as detected by electron microscopy). HearMNPV shows a different host range compared with H. armigera single-nucleocapsid NPV (HearSNPV). To better understand HearMNPV, the HearMNPV genome was sequenced and analyzed. Methods The morphology of HearMNPV was observed by electron microscope. The qPCR was used to determine the replication kinetics of HearMNPV infectious for H. armigera in vivo. A random genomic library of HearMNPV was constructed according to the “partial filling-in” method, the sequence and organization of the HearMNPV genome was analyzed and compared with sequence data from other baculoviruses. Results Real time qPCR showed that HearMNPV DNA replication included a decreasing phase, latent phase, exponential phase, and a stationary phase during infection of H. armigera. The HearMNPV genome consists of 154,196 base pairs, with a G + C content of 40.07%. 162 putative ORFs were detected in the HearMNPV genome, which represented 90.16% of the genome. The remaining 9.84% constitute four homologous regions and other non-coding regions. The gene content and gene arrangement in HearMNPV were most similar to those of Mamestra configurata NPV-B (MacoNPV-B), but was different to HearSNPV. Comparison of the genome of HearMNPV and MacoNPV-B suggested that HearMNPV has a deletion of a 5.4-kb fragment containing five ORFs. In addition, HearMNPV orf66, bro genes, and hrs are different to the corresponding parts of the MacoNPV-B genome. Conclusions HearMNPV can replicate in vivo in H. armigera and in vitro, and is a new NPV isolate distinguished from HearSNPV. HearMNPV is most closely related to MacoNPV-B, but has a distinct genomic structure, content, and organization. PMID:22913743

A Novel Binary Mixture of Helicoverpa armigera Single Nucleopolyhedrovirus Genotypic Variants Has Improved Insecticidal Characteristics for Control of Cotton Bollworms.

PubMed

Arrizubieta, Maite; Simón, Oihane; Williams, Trevor; Caballero, Primitivo

2015-06-15

The genotypic diversity of two Spanish isolates of Helicoverpa armigera single nucleopolyhedrovirus (HearSNPV) was evaluated with the aim of identifying mixtures of genotypes with improved insecticidal characteristics for control of the cotton bollworm. Two genotypic variants, HearSP1A and HearSP1B, were cloned in vitro from the most pathogenic wild-type isolate of the Iberian Peninsula, HearSNPV-SP1 (HearSP1-wt). Similarly, six genotypic variants (HearLB1 to -6) were obtained by endpoint dilution from larvae collected from cotton crops in southern Spain that died from virus disease during laboratory rearing. Variants differed significantly in their insecticidal properties, pathogenicity, speed of kill, and occlusion body (OB) production (OBs/larva). HearSP1B was ∼3-fold more pathogenic than HearSP1-wt and the other variants. HearLB1, HearLB2, HeaLB5, and HearLB6 were the fastest-killing variants. Moreover, although highly virulent, HearLB1, HearLB4, and HearLB5 produced more OBs/larva than did the other variants. The co-occluded HearSP1B:LB6 mixture at a 1:1 proportion was 1.7- to 2.8-fold more pathogenic than any single variant and other mixtures tested and also killed larvae as fast as the most virulent genotypes. Serial passage resulted in modified proportions of the component variants of the HearSP1B:LB6 co-occluded mixture, suggesting that transmissibility could be further improved by this process. We conclude that the improved insecticidal phenotype of the HearSP1B:LB6 co-occluded mixture underlines the utility of the genotypic variant dissection and reassociation approach for the development of effective virus-based insecticides. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Production and Characterization of Bacillus thuringiensis Cry1Ac-Resistant Cotton Bollworm Helicoverpa zea (Boddie)▿

PubMed Central

Anilkumar, Konasale J.; Rodrigo-Simón, Ana; Ferré, Juan; Pusztai-Carey, Marianne; Sivasupramaniam, Sakuntala; Moar, William J.

2008-01-01

Laboratory-selected Bacillus thuringiensis-resistant colonies are important tools for elucidating B. thuringiensis resistance mechanisms. However, cotton bollworm, Helicoverpa zea, a target pest of transgenic corn and cotton expressing B. thuringiensis Cry1Ac (Bt corn and cotton), has proven difficult to select for stable resistance. Two populations of H. zea (AR and MR), resistant to the B. thuringiensis protein found in all commercial Bt cotton varieties (Cry1Ac), were established by selection with Cry1Ac activated toxin (AR) or MVP II (MR). Cry1Ac toxin reflects the form ingested by H. zea when feeding on Bt cotton, whereas MVP II is a Cry1Ac formulation used for resistance selection and monitoring. The resistance ratio (RR) for AR exceeded 100-fold after 11 generations and has been maintained at this level for nine generations. This is the first report of stable Cry1Ac resistance in H. zea. MR crashed after 11 generations, reaching only an RR of 12. AR was only partially cross-resistant to MVP II, suggesting that MVP II does not have the same Cry1Ac selection pressure as Cry1Ac toxin against H. zea and that proteases may be involved with resistance. AR was highly cross-resistant to Cry1Ab toxin but only slightly cross-resistant to Cry1Ab expressing corn leaf powder. AR was not cross-resistant to Cry2Aa2, Cry2Ab2-expressing corn leaf powder, Vip3A, and cypermethrin. Toxin-binding assays showed no significant differences, indicating that resistance was not linked to a reduction in binding. These results aid in understanding why this pest has not evolved B. thuringiensis resistance, and highlight the need to choose carefully the form of B. thuringiensis protein used in experiments. PMID:18024681

Field evaluation of a botanical formulation from the milky mangrove Excoecaria agallocha L. against Helicoverpa armigera Hübner. in Abelmoschus esculentus (lady's finger) and Cajanus cajan (pigeon pea).

PubMed

Santhanam, Satyan Ramachandran; Egigu, Meseret C

2014-09-01

To evaluate a formulation from the milky mangrove tree Excoecaria agallocha L. (E. agallocha) against Helicoverpa armigera Hubner (H. armigera). About 3% aqueous ethanolic spray formulation derived from the lipophilic extract of E. agallocha (dry leaf) was evaluated against H. armigera in Abelmoschus esculentus (lady's finger) and Cajanus cajan (C. cajan) (pigeon pea), under field conditions. On the 9th day of the 4th spray the larval count in the plot treated with 3% E. agallocha formulation drastically came down to 0.23 larva/plant, compared to 1.63 in the ethanol control plot and 1.60 in the unsprayed plot. Blocks sprayed with 3% E. agallocha formulation yielded 35.8 quintals/hectare (q/ha) of healthy pods compared to Ekalux® (pod yield: 60.7 q/ha), 3% Vijay Neem® (60.22 q/ha), yield plot (6 q/ha) and ethanol control (7 q/ha). In C. cajan, 1% E. agallocha, 3% Nimbecidine® and 0.07% indoxacarb were equally potent in reducing the larval population of H. armigera and the non-target pest Spilosoma obliqua to 0%, from the 9th day (3rd spray). Indoxacarb plot recorded the maximum yield of 16.1 q/ha with 2.4% pod damage. Plots sprayed with 1% E. agallocha yielded 14.7 q/ha with 2.32% pod damage. The effect of 3% Nimbecidine® spray (14.35 q/ha) was comparable to E. agallocha formulation. Unsprayed and ethanol control plots yielded 12.41 and 11.2 q/ha of pods with an average pod damage of 4.7%. E. agallocha formulation was found to be promising for the control of H. armigera, under field conditions. Copyright © 2014 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

The potential distribution of invading Helicoverpa armigera in North America: is it just a matter of time?

PubMed

Kriticos, Darren J; Ota, Noboru; Hutchison, William D; Beddow, Jason; Walsh, Tom; Tay, Wee Tek; Borchert, Daniel M; Paula-Moraes, Silvana V; Paula-Moreas, Silvana V; Czepak, Cecília; Zalucki, Myron P

2015-01-01

Helicoverpa armigera has recently invaded South and Central America, and appears to be spreading rapidly. We update a previously developed potential distribution model to highlight the global invasion threat, with emphasis on the risks to the United States. The continued range expansion of H. armigera in Central America is likely to change the invasion threat it poses to North America qualitatively, making natural dispersal from either the Caribbean islands or Mexico feasible. To characterise the threat posed by H. armigera, we collated the value of the major host crops in the United States growing within its modelled potential range, including that area where it could expand its range during favourable seasons. We found that the annual value of crops that would be exposed to H. armigera totalled approximately US$78 billion p.a., with US$843 million p.a. worth growing in climates that are optimal for the pest. Elsewhere, H. armigera has developed broad-spectrum pesticide resistance; meaning that if it invades the United States, protecting these crops from significant production impacts could be challenging. It may be cost-effective to undertake pre-emptive biosecurity activities such as slowing the spread of H. armigera throughout the Americas, improving the system for detecting H. armigera, and methods for rapid identification, especially distinguishing between H. armigera, H. zea and potential H. armigera x H. zea hybrids. Developing biological control programs, especially using inundative techniques with entomopathogens and parasitoids could slow the spread of H. armigera, and reduce selective pressure for pesticide resistance. The rapid spread of H. armigera through South America into Central America suggests that its spread into North America is a matter of time. The likely natural dispersal routes preclude aggressive incursion responses, emphasizing the value of preparatory communication with agricultural producers in areas suitable for invasion by H. armigera.

Helicoverpa zea (Lepidoptera: Noctuidae) and Spodoptera frugiperda (Lepidoptera: Noctuidae) Responses to Sorghum bicolor (Poales: Poaceae) Tissues From Lowered Lignin Lines.

PubMed

Dowd, Patrick F; Sattler, Scott E

2015-01-01

The presence of lignin within biomass impedes the production of liquid fuels. Plants with altered lignin content and composition are more amenable to lignocellulosic conversion to ethanol and other biofuels but may be more susceptible to insect damage where lignin is an important resistance factor. However, reduced lignin lines of switchgrasses still retained insect resistance in prior studies. Therefore, we hypothesized that sorghum lines with lowered lignin content will also retain insect resistance. Sorghum excised leaves and stalk pith Sorghum bicolor (L.) Moench (Poales: Poaceae) from near isogenic brown midrib (bmr) 6 and 12 mutants lines, which have lowered lignin content and increased lignocellulosic ethanol conversion efficiency, were examined for insect resistance relative to wild-type (normal BTx623). Greenhouse and growth chamber grown plant tissues were fed to first-instar larvae of corn earworms, Helicoverpa zea (Boddie) and fall armyworms Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), two sorghum major pests. Younger bmr leaves had significantly greater feeding damage in some assays than wild-type leaves, but older bmr6 leaves generally had significantly less damage than wild-type leaves. Caterpillars feeding on the bmr6 leaves often weighed significantly less than those feeding on wild-type leaves, especially in the S. frugiperda assays. Larvae fed the pith from bmr stalks had significantly higher mortality compared with those larvae fed on wild-type pith, which suggested that bmr pith was more toxic. Thus, reducing lignin content or changing subunit composition of bioenergy grasses does not necessarily increase their susceptibility to insects and may result in increased resistance, which would contribute to sustainable production. Published by Oxford University Press on behalf of the Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

The Potential Distribution of Invading Helicoverpa armigera in North America: Is It Just a Matter of Time?

PubMed Central

Kriticos, Darren J.; Ota, Noboru; Hutchison, William D.; Beddow, Jason; Walsh, Tom; Tay, Wee Tek; Borchert, Daniel M.; Paula-Moreas, Silvana V.; Czepak, Cecília; Zalucki, Myron P.

2015-01-01

Helicoverpa armigera has recently invaded South and Central America, and appears to be spreading rapidly. We update a previously developed potential distribution model to highlight the global invasion threat, with emphasis on the risks to the United States. The continued range expansion of H. armigera in Central America is likely to change the invasion threat it poses to North America qualitatively, making natural dispersal from either the Caribbean islands or Mexico feasible. To characterise the threat posed by H. armigera, we collated the value of the major host crops in the United States growing within its modelled potential range, including that area where it could expand its range during favourable seasons. We found that the annual value of crops that would be exposed to H. armigera totalled approximately US$78 billion p.a., with US$843 million p.a. worth growing in climates that are optimal for the pest. Elsewhere, H. armigera has developed broad-spectrum pesticide resistance; meaning that if it invades the United States, protecting these crops from significant production impacts could be challenging. It may be cost-effective to undertake pre-emptive biosecurity activities such as slowing the spread of H. armigera throughout the Americas, improving the system for detecting H. armigera, and methods for rapid identification, especially distinguishing between H. armigera, H. zea and potential H. armigera x H. zea hybrids. Developing biological control programs, especially using inundative techniques with entomopathogens and parasitoids could slow the spread of H. armigera, and reduce selective pressure for pesticide resistance. The rapid spread of H. armigera through South America into Central America suggests that its spread into North America is a matter of time. The likely natural dispersal routes preclude aggressive incursion responses, emphasizing the value of preparatory communication with agricultural producers in areas suitable for invasion by H. armigera. PMID:25786260

Isotopes and Trace Elements as Natal Origin Markers of Helicoverpa armigera – An Experimental Model for Biosecurity Pests

PubMed Central

Holder, Peter W.; Armstrong, Karen; Van Hale, Robert; Millet, Marc-Alban; Frew, Russell; Clough, Timothy J.; Baker, Joel A.

2014-01-01

Protecting a nation's primary production sector and natural estate is heavily dependent on the ability to determine the risk presented by incursions of exotic insect species. Identifying the geographic origin of such biosecurity breaches can be crucial in determining this risk and directing the appropriate operational responses and eradication campaigns, as well as ascertaining incursion pathways. Reading natural abundance biogeochemical markers using mass spectrometry is a powerful tool for tracing ecological pathways as well as provenance determination of commercial products and items of forensic interest. However, application of these methods to trace insects has been underutilised to date and our understanding in this field is still in a phase of basic development. In addition, biogeochemical markers have never been considered in the atypical situation of a biosecurity incursion, where sample sizes are often small, and of unknown geographic origin and plant host. These constraints effectively confound the interpretation of the one or two isotope geo-location markers systems that are currently used, which are therefore unlikely to achieve the level of provenance resolution required in biosecurity interceptions. Here, a novel approach is taken to evaluate the potential for provenance resolution of insect samples through multiple biogeochemical markers. The international pest, Helicoverpa armigera, has been used as a model species to assess the validity of using naturally occurring δ2H, 87Sr/86Sr, 207Pb/206Pb and 208Pb/206Pb isotope ratios and trace element concentration signatures from single moth specimens for regional assignment to natal origin. None of the biogeochemical markers selected were individually able to separate moths from the different experimental regions (150–3000 km apart). Conversely, using multivariate analysis, the region of origin was correctly identified for approximately 75% of individual H. armigera samples. The geographic resolution demonstrated with this approach has considerable potential for biosecurity as well as other disciplines including forensics, ecology and pest management. PMID:24664236

Fluorescence in insects

NASA Astrophysics Data System (ADS)

Welch, Victoria L.; Van Hooijdonk, Eloise; Intrater, Nurit; Vigneron, Jean-Pol

2012-10-01

Fluorescent molecules are much in demand for biosensors, solar cells, LEDs and VCSEL diodes, therefore, considerable efforts have been expended in designing and tailoring fluorescence to specific technical applications. However, naturally occurring fluorescence of diverse types has been reported from a wide array of living organisms: most famously, the jellyfish Aequorea victoria, but also in over 100 species of coral and in the cuticle of scorpions, where it is the rule, rather than the exception. Despite the plethora of known insect species, comparatively few quantitative studies have been made of insect fluorescence. Because of the potential applications of natural fluorescence, studies in this field have relevance to both physics and biology. Therefore, in this paper, we review the literature on insect fluorescence, before documenting its occurrence in the longhorn beetles Sternotomis virescens, Sternotomis variabilis var. semi rufescens, Anoplophora elegans and Stellognatha maculata, the tiger beetles Cicindela maritima and Cicindela germanica and the weevil Pachyrrhynchus gemmatus purpureus. Optical features of insect fluorescence, including emitted wavelength, molecular ageing and naturally occurring combinations of fluorescence with bioluminescence and colour-producing structures are discussed.

Use of a pooled clone method to isolate a novel Bacillus thuringiensis Cry2A toxin with activity against Ostrinia furnacalis.

PubMed

Shu, Changlong; Zhang, Jingtao; Chen, Guihua; Liang, Gemei; He, Kanglai; Crickmore, Neil; Huang, Dafang; Zhang, Jie; Song, Fuping

2013-09-01

A pooled clone method was developed to screen for cry2A genes. This metagenomic method avoids the need to analyse isolated Bacillus thuringiensis strains by performing gene specific PCR on plasmid-enriched DNA prepared from a pooled soil sample. Using this approach the novel holotype gene cry2Ah1 was cloned and characterized. The toxin gene was over-expressed in Escherichia coli Rosetta (DE3) and the expressed toxin accumulated in both the soluble and insoluble fractions. The soluble Cry2Ah1 was found to have a weight loss activity against Ostrinia furnacalis, and a growth inhibitory activity to both Cry1Ac-susceptible and resistant Helicoverpa armigera populations. Copyright © 2013 Elsevier Inc. All rights reserved.

Screening of broad spectrum natural pesticides against conserved target arginine kinase in cotton pests by molecular modeling.

PubMed

Sakthivel, Seethalakshmi; Habeeb, S K M; Raman, Chandrasekar

2018-03-12

Cotton is an economically important crop and its production is challenged by the diversity of pests and related insecticide resistance. Identification of the conserved target across the cotton pest will help to design broad spectrum insecticide. In this study, we have identified conserved sequences by Expressed Sequence Tag profiling from three cotton pests namely Aphis gossypii, Helicoverpa armigera, and Spodoptera exigua. One target protein arginine kinase having a key role in insect physiology and energy metabolism was studied further using homology modeling, virtual screening, molecular docking, and molecular dynamics simulation to identify potential biopesticide compounds from the Zinc natural database. We have identified four compounds having excellent inhibitor potential against the identified broad spectrum target which are highly specific to invertebrates.

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.

High Susceptibility to Cry1Ac and Low Resistance Allele Frequency Reduce the Risk of Resistance of Helicoverpa armigers to Bt Soybean in Brazil.

PubMed

Dourado, Patrick M; Bacalhau, Fabiana B; Amado, Douglas; Carvalho, Renato A; Martinelli, Samuel; Head, Graham P; Omoto, Celso

2016-01-01

The Old World bollworm, Helicoverpa armigera (Hübner), was recently introduced into Brazil, where it has caused extensive damage to cotton and soybean crops. MON 87701 × MON 89788 soybean, which expresses the Bt protein Cry1Ac, was recently deployed in Brazil, providing high levels of control against H. armigera. To assess the risk of resistance to the Cry1Ac protein expressed by MON 87701 × MON 89788 soybean in Brazil, we conducted studies to evaluate the baseline susceptibility of H. armigera to Cry1Ac, in planta efficacy including the assessment of the high-dose criterion, and the initial resistance allele frequency based on an F2 screen. The mean Cry1Ac lethal concentration (LC50) ranged from 0.11 to 1.82 μg·mL-1 of diet among all H. armigera field populations collected from crop seasons 2013/14 to 2014/15, which indicated about 16.5-fold variation. MON 87701 × MON 89788 soybean exhibited a high level of efficacy against H. armigera and most likely met the high dose criterion against this target species in leaf tissue dilution bioassays up to 50 times. A total of 212 F2 family lines of H. armigera were established from field collections sampled from seven locations across Brazil and were screened for the presence of MON 87701 × MON 89788 soybean resistance alleles. None of the 212 families survived on MON 87701 × MON 89788 soybean leaf tissue (estimated allele frequency = 0.0011). The responses of H. armigera to Cry1Ac protein, high susceptibility to MON 87701 × MON 89788 soybean, and low frequency of resistance alleles across the main soybean-producing regions support the assumptions of a high-dose/refuge strategy. However, maintenance of reasonable compliance with the refuge recommendation will be essential to delay the evolution of resistance in H. armigera to MON 87701 × MON 89788 soybean in Brazil.

Impact of the Stem Extract of Thevetia neriifolia on the Feeding Potential and Histological Architecture of the Midgut Epithelial Tissue of Early Fourth Instars of Helicoverpa armigera Hübner

PubMed Central

Mishra, Monika; Gupta, Kamal Kumar; Kumar, Sarita

2015-01-01

Helicoverpa armigera Hübner is one of the most important agricultural crop pests in the world causing heavy crop yield losses. The continued and indiscriminate use of synthetic insecticides in agriculture for their control has received wide public apprehension because of multifarious problems, including insecticide resistance, resurgence of pest species, environmental pollution, and toxic hazards to humans and nontarget organisms. These problems have necessitated the need to explore and develop alternative strategies using eco-friendly and biodegradable plant products. In view of this, the efficacy of Thevetia neriifolia methanol stem extract was evaluated against the early fourth instars of H. armigera as an antifeedant and stomach poison agent. Feeding of larvae with the diet containing 0.005%–5.0% extract resulted in 2.06%–37.35% antifeedant index; the diet with 5.0% extract caused 54.3% reduced consumption. The negative impact of extract on larval feeding resulted in 37.5%–77.7% starvation, causing adverse effects on the larval weight. Choice between control and experimental diet resulted in feeding preference of larvae for the control diet, leading to 7.3%–42.9% reduced consumption of extract-containing diet. The only exception was the diet with 0.005% extract, which could not cause any deterrence. The midgut histological architecture of H. armigera larvae fed with 0.005%–0.05% extract-containing diet with negligible antifeedant potential showed significant damage, shrinkage, and distortion and vacuolization of gut tissues and peritrophic membrane, causing the disintegration of epithelial, goblet, and regenerative cells; the damage increased with the increase in concentration. These changes in the gut caused negative impact on the digestion and absorption of food and thus nutritional deficiency in the larvae, which could probably affect their growth and development. This study reveal the appreciable stomach poison potential of T. neriifolia stem methanol extract against H. armigera larvae, which can be explored as an eco-friendly pest control strategy. PMID:26813920

Induced resistance in soybean toHelicoverpa zea: Role of plant protein quality.

PubMed

Bi, J L; Felton, G W; Mueller, A J

1994-01-01

Resistance in soybean toHelicoverpa zea is comprised of both constitutive and inducible factors. In this study, we investigated the induction of resistance byH. zea in both greenhouse and field studies. In a greenhouse experiment, fourth-instarH. zea growth rates were reduced by 39% after 24 hr feeding and by 27% after 48 hr when larvae fed on previously wounded V3 foliage (cv. Forrest) compared with undamaged foliage. In a field study, the weight gain by larvae was more than 52% greater when larvae fed for 72 hr on undamaged R2/R3 soybean plants (cv. Braxton) compared to those that fed on previously wounded plants. A significant component of the induced resistance is due to a decline in the nutritional quality of foliar protein following foliar damage byH. zea. Foliar protein was extracted from damaged and undamaged foliage and incorporated into artificial diets. Larval growth was reduced 26% after four days and 49% after seven days on diets containing protein from damaged plants compared to larvae feeding on foliar protein from undamaged plants. Chemical analyses of protein quality also indicated a decline in quality in damaged plants compared to unwounded plants. Increases in lipoxygenase activity (53%), lipid peroxidation products (20%), and trypsin inhibitor content (34%) were observed in protein from wounded plants. Moreover, a 5.9% loss in free amines and 19% loss in total thiols occurred in protein from wounded plants. Larval feeding causes a significant increase in foliar lipoxygenase activity that varied among genotypes. Lipoxygenase isozymes were measured at pH 5.5, pH 7.0, and pH 8.5 in V3 stage plants of Forrest, Hark, D75-1069, and PI 417061 genotypes. Lipoxygenase activity in each genotype was significantly increased after 72 hr of larval feeding at each pH level tested, with the exception of lipoxygenase isozymes at pH 5.5 in genotype PI 417061. Larval feeding on R2/R3 stage plants (field-grown cv. Braxton) for six days also increased foliar lipoxygenase activity.

Mass production of polyhedral occlusion bodies of NPV of Helicoverpa armigera in relation to dose, age and larval weight.

PubMed

Narayanan, K; Jayaraj, S

2002-07-01

A significant difference was noticed in the yield of polyhedral occlusion bodies (POBs) in various larval instars of H. armigera when three different doses of the nuclear polyhedrosis virus (NPV) were administered. The yield of POBs from a single larva ranged from 0.35 x 10(6) to 25033.33 x 10(6) with a mean of 18422.33 x 10(6) for fourth instar inoculated. Positive correlation existed between larval weight and number of POBs recovered. The regression analysis indicated POBs recovered responded with predictable manner to the weight of different larval instars and the various concentration of virus administered. The medium lethal time increased in the instars of the larva advanced with a minimum of 3.5 and maximum of 8 days in the first and fifth instars respectively.

Group I but not group II NPV induces antiviral effects in mammalian cells.

PubMed

Liang, Changyong; Song, Jianhua; Hu, Zhihong; Chen, Xinwen

2006-10-01

Nucleopolyhedrovirus (NPV) is divided into Group I and Group II based on the phylogenetic analysis. It has been reported that Group I NPVs such as Autographa californica multiple NPV (AcMNPV) can transduce mammalian cells, while Group II NPVs such as Helicoverpa armigera single NPV (HaSNPV) cannot. Here we report that AcMNPV was capable of stimulating antiviral activity in human hepatoma cells (SMMC-7721) manifested by inhibition of Vesicular Stomatitis virus (VSV) replication. In contrast, the HaSNPV and the Spodoptera exigua multiple NPV (SeMNPV) of group II had no inhibitory effect on VSV. Recombinant AcMNPV was shown to induce interferons alpha/beta even in the absence of transgene expression in human SMMC-7721 cells, while it mediated transgene expression in BHK and L929 mammalian cells without an ensuing antiviral activity.

The genera Isorineloricaria and Aphanotorulus (Siluriformes: Loricariidae)
with description of a new species.

PubMed

Ray, C Keith; Armbruster, Jonathan W

2016-02-04

We review the complex history of those species included in the Hypostomus emarginatus species complex and recognize them in Isorineloricaria and Aphanotorulus. Isorineloricaria consists of four valid species: I. acuarius n. sp., I. spinosissima, I. tenuicauda, and I. villarsi. Aphanotorulus consists of six valid species: A. ammophilus, A, emarginatus, A. gomesi, A. horridus, A. phrixosoma, and A. unicolor. Plecostomus annae and Hypostoma squalinum are placed in the synonymy of A. emarginatus; Plecostomus biseriatus, P. scopularius, and P. virescens are placed in the synonymy of A. horridus; Plecostomus winzi is placed in the synonymy of I. tenuicauda, and one new species, I. acuarius is described from the Apure River basin of Venezuela. Aphanotoroulus can be distinguished from Isorineloricaria by having caudal peduncles that do not become greatly lengthed with size and that are oval in cross section (vs. caudal peduncle proportions that get proportionately longer with size and that become round in cross-section), and by having small dark spots (less than half plate diameter) on a light tan background (vs. spots almost as large as lateral plates on a nearly white background.

Whole genome re-sequencing of date palms yields insights into diversification of a fruit tree crop.

PubMed

Hazzouri, Khaled M; Flowers, Jonathan M; Visser, Hendrik J; Khierallah, Hussam S M; Rosas, Ulises; Pham, Gina M; Meyer, Rachel S; Johansen, Caryn K; Fresquez, Zoë A; Masmoudi, Khaled; Haider, Nadia; El Kadri, Nabila; Idaghdour, Youssef; Malek, Joel A; Thirkhill, Deborah; Markhand, Ghulam S; Krueger, Robert R; Zaid, Abdelouahhab; Purugganan, Michael D

2015-11-09

Date palms (Phoenix dactylifera) are the most significant perennial crop in arid regions of the Middle East and North Africa. Here, we present a comprehensive catalogue of approximately seven million single nucleotide polymorphisms in date palms based on whole genome re-sequencing of a collection of 62 cultivars. Population structure analysis indicates a major genetic divide between North Africa and the Middle East/South Asian date palms, with evidence of admixture in cultivars from Egypt and Sudan. Genome-wide scans for selection suggest at least 56 genomic regions associated with selective sweeps that may underlie geographic adaptation. We report candidate mutations for trait variation, including nonsense polymorphisms and presence/absence variation in gene content in pathways for key agronomic traits. We also identify a copia-like retrotransposon insertion polymorphism in the R2R3 myb-like orthologue of the oil palm virescens gene associated with fruit colour variation. This analysis documents patterns of post-domestication diversification and provides a genomic resource for this economically important perennial tree crop.

Mutually opposing forces during locomotion can eliminate the tradeoff between maneuverability and stability

NASA Astrophysics Data System (ADS)

Cowan, Noah; Sefati, Shahin; Neveln, Izaak; Roth, Eatai; Mitchell, Terence; Snyder, James; Maciver, Malcolm; Fortune, Eric

A surprising feature of animal locomotion is that organisms typically produce substantial forces in directions other than what is necessary to move the animal through its environment, such as perpendicular to, or counter to, the direction of travel. The effect of these forces has been difficult to observe because they are often mutually opposing and therefore cancel out. Using a combination of robotic physical modeling, computational modeling, and biological experiments, we discovered that these forces serve an important role: to simplify and enhance the control of locomotion. Specifically, we examined a well-suited model system, the glass knifefish Eigenmannia virescens, which produces mutually opposing forces during a hovering behavior. By systematically varying the locomotor parameters of our biomimetic robot, and measuring the resulting forces and kinematics, we demonstrated that the production and differential control of mutually opposing forces is a strategy that generates passive stabilization while simultaneously enhancing maneuverability. Mutually opposing forces during locomotion are widespread across animal taxa, and these results indicate that such forces can eliminate the tradeoff between stability and maneuverability, thereby simplifying robotic and neural control.

Whole genome re-sequencing of date palms yields insights into diversification of a fruit tree crop

PubMed Central

Hazzouri, Khaled M.; Flowers, Jonathan M.; Visser, Hendrik J.; Khierallah, Hussam S. M.; Rosas, Ulises; Pham, Gina M.; Meyer, Rachel S.; Johansen, Caryn K.; Fresquez, Zoë A.; Masmoudi, Khaled; Haider, Nadia; El Kadri, Nabila; Idaghdour, Youssef; Malek, Joel A.; Thirkhill, Deborah; Markhand, Ghulam S.; Krueger, Robert R.; Zaid, Abdelouahhab; Purugganan, Michael D.

2015-01-01

Date palms (Phoenix dactylifera) are the most significant perennial crop in arid regions of the Middle East and North Africa. Here, we present a comprehensive catalogue of approximately seven million single nucleotide polymorphisms in date palms based on whole genome re-sequencing of a collection of 62 cultivars. Population structure analysis indicates a major genetic divide between North Africa and the Middle East/South Asian date palms, with evidence of admixture in cultivars from Egypt and Sudan. Genome-wide scans for selection suggest at least 56 genomic regions associated with selective sweeps that may underlie geographic adaptation. We report candidate mutations for trait variation, including nonsense polymorphisms and presence/absence variation in gene content in pathways for key agronomic traits. We also identify a copia-like retrotransposon insertion polymorphism in the R2R3 myb-like orthologue of the oil palm virescens gene associated with fruit colour variation. This analysis documents patterns of post-domestication diversification and provides a genomic resource for this economically important perennial tree crop. PMID:26549859

Dynamic modulation of visual and electrosensory gains for locomotor control

PubMed Central

Sutton, Erin E.; Demir, Alican; Stamper, Sarah A.; Fortune, Eric S.; Cowan, Noah J.

2016-01-01

Animal nervous systems resolve sensory conflict for the control of movement. For example, the glass knifefish, Eigenmannia virescens, relies on visual and electrosensory feedback as it swims to maintain position within a moving refuge. To study how signals from these two parallel sensory streams are used in refuge tracking, we constructed a novel augmented reality apparatus that enables the independent manipulation of visual and electrosensory cues to freely swimming fish (n = 5). We evaluated the linearity of multisensory integration, the change to the relative perceptual weights given to vision and electrosense in relation to sensory salience, and the effect of the magnitude of sensory conflict on sensorimotor gain. First, we found that tracking behaviour obeys superposition of the sensory inputs, suggesting linear sensorimotor integration. In addition, fish rely more on vision when electrosensory salience is reduced, suggesting that fish dynamically alter sensorimotor gains in a manner consistent with Bayesian integration. However, the magnitude of sensory conflict did not significantly affect sensorimotor gain. These studies lay the theoretical and experimental groundwork for future work investigating multisensory control of locomotion. PMID:27170650

The fish fauna in tropical rivers: the case of the Sorocaba River basin, São Paulo, Brazil.

PubMed

Smith, Welber Senteio; Petrere Júnior, Miguel; Barrella, Walter

2003-01-01

A survey was carried out on the fish species in the Sorocaba River basin, the main tributary of the left margin of the Tietê River, located in the State of São Paulo, Brazil. The species were collected with gill nets. After identification of the specimens, their relative abundance, weight and standard length were determined. Up to the present moment there are not any studies that focus this subject in this hydrographic basin. Fifty-three species, distributed in eighteen families and six orders were collected. Characiformes were represented by twenty-eight species, Siluriformes by seventeen species, the Gymnotiformes by three species, Perciformes and Cyprinodontiformes by two species, and the Synbranchiformes by one species. Among the collected species there were two exotic. The most abundant species were Astyanax fasciatus and Hypostomus ancistroides. In relation to total weight the most representative species were Hoplias malabaricus and Hypostomus ancistroides. Cyprinus carpio, Prochilodus lineatus, Schizodon nasutus and Hoplias malabaricus were the most representative species in relation to average weight. Largest standard length were recorded for Sternopygus macrurus, Steindachnerina insculpta, Eigenmannia aff. virescens and Cyprinus carpio.

Impacts of transgenic poplar-cotton agro-ecosystems upon target pests and non-target insects under field conditions.

PubMed

Zhang, D J; Liu, J X; Lu, Z Y; Li, C L; Comada, E; Yang, M S

2015-07-27

Poplar-cotton agro-ecosystems are the main agricultural planting modes of cotton fields in China. With increasing acres devoted to transgenic insect-resistant poplar and transgenic insect-resistant cotton, studies examining the effects of transgenic plants on target and non-target insects become increasingly important. We systematically surveyed populations of both target pests and non-target insects for 4 different combinations of poplar-cotton eco-systems over 3 years. Transgenic Bt cotton strongly resisted the target insects Fall webworm moth [Hyphantria cunea (Drury)], Sylepta derogata Fabrieius, and American bollworm (Heliothis armigera), but no clear impact on non-target insect cotton aphids (Aphis gossypii). Importantly, intercrops containing transgenic Pb29 poplar significantly increased the inhibitory effects of Bt cotton on Fall webworm moth in ecosystem IV. Highly resistant Pb29 poplar reduced populations of the target pests Grnsonoma minutara Hubner and non-target insect poplar leaf aphid (Chaitophorus po-pulialbae), while Fall webworm moth populations were unaffected. We determined the effects of Bt toxin from transgenic poplar and cotton on target and non-target pests in different ecosystems of cotton-poplar intercrops and identified the synergistic effects of such combinations toward both target and non-target insects.

Safety assessment and detection method of genetically modified Chinese Kale (Brassica oleracea cv. alboglabra ).

PubMed

Lin, Chih-Hui; Lu, Chien-Te; Lin, Hsin-Tang; Pan, Tzu-Ming

2009-03-11

Sporamins are tuberous storage proteins and account for 80% of soluble protein in sweet potato tubers with trypsin-inhibitory activity. The expression of sporamin protein in transgenic Chinese kale (line BoA 3-1) conferred insecticidal activity toward corn earworm [ Helicoverpa armigera (Hubner)] in a previous report. In this study, we present a preliminary safety assessment of transgenic Chinese kale BoA 3-1. Bioinformatic and simulated gastric fluid (SGF) analyses were performed to evaluate the allergenicity of sporamin protein. The substantial equivalence between transgenic Chinese kale and its wild-type host has been demonstrated by the comparison of important constituents. A reliable real-time polymerase chain reaction (PCR) detection method was also developed to control sample quality. Despite the results of most evaluations in this study being negative, the safety of sporamin in transgenic Chinese kale BoA 3-1 was uncluded because of the allergenic risk revealed by bioinformatic analysis.

Comparative performance of modified full-length and truncated Bacillus thuringiensis-cry1Ac genes in transgenic tomato.

PubMed

Koul, Bhupendra; Yadav, Reena; Sanyal, Indraneel; Amla, Devindra Vijay

2015-01-01

Bt-cry1Ac gene has been reputedly effective against Helicoverpa armigera a notorious lepidopteran pest. Reports on the expression of full-length and truncated cry1Ac genes in plants for effective resistance against Helicoverpa sp. have been documented however, their performance is still ambiguous. Moreover, the question remains to be addressed that truncation of 3' end of the native gene was documented and suggested for active insecticidal toxin production while the most successful transgenic event(s) of commercialized-cotton are based on full-length of the cry gene. Therefore, we performed a comparative study on the efficacy of the two versions of cry1Ac genes (full-length: 3,510 bp and truncated: 1,845 bp) in T0 and T1 transgenic tomato plants and analyzed the extent of protection against H. armigera and also compared the results with our previous findings related to a successful transgenic tomato line Ab25E, expressing cry1Ab gene. The integration of cry1Ac gene(s) in T0 transgenic plants and its inheritance in T1 progeny was observed by PCR, RT-PCR and Southern blot hybridization analysis while, the toxin integrity, expression and toxicity was monitored by Western immunoassay, DAS-ELISA and insect bioassay respectively. An average transformation frequency and Bt-Cry protein content of 16.93 ± 2.10 and 0.0020-0.0128% of total soluble protein (TSP) was obtained with pRD400 vector (Trcry1Ac) while, a much lower value of 9.30 ± 2.041 and 0.0001 - 0.0026% of TSP was observed with pNBRI-1 vector (Flcry1Ac), respectively. The promising Trcry1Ac T0 transgenic plants and their T1 progeny gave full protection from H. armigera. Although Flcry1Ac gene showed lower transformation frequency and lower expression, it showed higher toxicity to H. armigera when compared with truncated Trcry1Ac gene. The full-length cry1Ac gene can be redesigned for higher expression and performance in dicots or a hybrid gene could be designed having a blend of strong receptor binding and stable expression characteristics for enhanced efficacy and toxicity to the susceptible insects.

Effect of Emamectin Benzoate on Mortality, Proboscis Extension, Gustation and Reproduction of the Corn Earworm, Helicoverpa zea

PubMed Central

López, Juan D.; Latheef, M. A.; Hoffmann, W. C.

2010-01-01

Newly emerged corn earworm adults, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) require a carbohydrate source from plant or other exudates and nectars for dispersal and reproduction. Adults actively seek and forage at feeding sites upon eclosion in the habitat of the larval host plant or during dispersal to, or colonization of, a suitable reproductive habitat. This nocturnal behavior of H. zea has potential for exploitation as a pest management strategy for suppression using an adult feeding approach. This approach entails the use of a feeding attractant and stimulant in combination with a toxicant that when ingested by the adult will either reduce fecundity/fertility at sub-lethal dosages or kill the adult. The intent of this study was to assess reproductive inhibition and toxicity of emamectin benzoate on H. zea when ingested by the adults when mixed in ppm active ingredient (wt:vol) with 2.5 M sucrose as a feeding stimulant. Because the mixture has to be ingested to function, the effect of emamectin benzoate was also evaluated at sub-lethal and lethal concentrations on proboscis extension and gustatory response of H. zea in the laboratory. Feral males captured in sex pheromone-baited traps in the field were used for toxicity evaluations because they were readily available and were more representative of the field populations than laboratory-reared adults. Laboratory-reared female moths were used for reproduction effects because it is very difficult to collect newly emerged feral females from the field. Emamectin benzoate was highly toxic to feral H. zea males with LC50 values (95% CL) being 0.718 (0.532–0.878), 0.525 (0.316–0.751), and 0.182 (0.06–0.294) ppm for 24, 48 and 72 h responses, respectively. Sub-lethal concentrations of emamectin benzoate did not significantly reduce proboscis extension response of feral males and gustatory response of female H. zea. Sublethal concentrations of emamectin benzoate significantly reduced percent larval hatch of eggs and mating frequency of female H. zea. Larval survival to the pupal stage was also significantly reduced by ingestion of emamectin benzoate by female H. zea. These data suggest that emamectin benzoate is a useful toxicant in an attract-and-kill control strategy against H. zea. Field studies are warranted to validate the results reported in this study. PMID:20673074

Effect of emamectin benzoate on mortality, proboscis extension, gustation and reproduction of the corn earworm, Helicoverpa zea.

PubMed

López, Juan D; Latheef, M A; Hoffmann, W C

2010-01-01

Newly emerged corn earworm adults, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) require a carbohydrate source from plant or other exudates and nectars for dispersal and reproduction. Adults actively seek and forage at feeding sites upon eclosion in the habitat of the larval host plant or during dispersal to, or colonization of, a suitable reproductive habitat. This nocturnal behavior of H. zea has potential for exploitation as a pest management strategy for suppression using an adult feeding approach. This approach entails the use of a feeding attractant and stimulant in combination with a toxicant that when ingested by the adult will either reduce fecundity/fertility at sub-lethal dosages or kill the adult. The intent of this study was to assess reproductive inhibition and toxicity of emamectin benzoate on H. zea when ingested by the adults when mixed in ppm active ingredient (wt:vol) with 2.5 M sucrose as a feeding stimulant. Because the mixture has to be ingested to function, the effect of emamectin benzoate was also evaluated at sub-lethal and lethal concentrations on proboscis extension and gustatory response of H. zea in the laboratory. Feral males captured in sex pheromone-baited traps in the field were used for toxicity evaluations because they were readily available and were more representative of the field populations than laboratory-reared adults. Laboratory-reared female moths were used for reproduction effects because it is very difficult to collect newly emerged feral females from the field. Emamectin benzoate was highly toxic to feral H. zea males with LC(50) values (95% CL) being 0.718 (0.532-0.878), 0.525 (0.316-0.751), and 0.182 (0.06-0.294) ppm for 24, 48 and 72 h responses, respectively. Sub-lethal concentrations of emamectin benzoate did not significantly reduce proboscis extension response of feral males and gustatory response of female H. zea. Sublethal concentrations of emamectin benzoate significantly reduced percent larval hatch of eggs and mating frequency of female H. zea. Larval survival to the pupal stage was also significantly reduced by ingestion of emamectin benzoate by female H. zea. These data suggest that emamectin benzoate is a useful toxicant in an attract-and-kill control strategy against H. zea. Field studies are warranted to validate the results reported in this study.

Antibiotics influence the toxicity of the delta endotoxins of Bacillus thuringiensis towards the cotton bollworm, Helicoverpa armigera.

PubMed

Paramasiva, Inakarla; Sharma, Hari C; Krishnayya, Pulipaka Venkata

2014-07-24

The cotton bollworm, Helicoverpa armigera is one of the most important crop pests worldwide. It has developed high levels of resistance to synthetic insecticides, and hence, Bacillus thuringiensis (Bt) formulations are used as a safer pesticide and the Bt genes have been deployed in transgenic crops for controlling this pest. There is an apprehension that H. armigera might develop resistance to transgenic crops in future. Therefore, we studied the role of gut microbes by eliminating them with antibiotics in H. armigera larvae on the toxicity of Bt toxins against this pest. Commercial formulation of Bt (Biolep®) and the pure Cry1Ab and Cry1Ac toxin proteins were evaluated at ED50, LC50, and LC90 dosages against the H. armigera larvae with and without antibiotics (which removed the gut microbes). Lowest H. armigera larval mortality due to Bt formulation and the Bt toxins Cry1Ab and Cry1Ac was recorded in insects reared on diets with 250 and 500 μg ml-1 diet of each of the four antibiotics (gentamicin, penicillin, rifampicin, and streptomycin), while the highest larval mortality was recorded in insects reared on diets without the antibiotics. Mortality of H. armigera larvae fed on diets with Bt formulation and the δ-endotoxins Cry1Ab and Cry1Ac was inversely proportional to the concentration of antibiotics in the artificial diet. Nearly 30% reduction in larval mortality was observed in H. armigera larvae from F1 to F3 generation when the larvae were reared on diets without antibiotics (with gut microbes) and fed on 0.15% Bt or 12 μg Cry1Ab or Cry1Ac ml-1 diet, indicating development of resistance to Bt in the presence of gut microflora. However, there were no differences in larval mortality due to Bt, Cry1Ab or Cry1Ac across generations in insects when they were reared on diets with 250 μg of each antibiotic ml-1 diet (without gut microflora). The results suggested that antibiotics which eliminated gut microflora influenced the toxicity of Bt towards H. armigera, and any variation in diversity and abundance of gut microflora will have a major bearing on development of resistance to Bt toxins applied as foliar sprays or deployed in transgenic crops for pest management.

Genome-wide analysis of ionotropic receptor gene repertoire in Lepidoptera with an emphasis on its functions of Helicoverpa armigera.

PubMed

Liu, Nai-Yong; Xu, Wei; Dong, Shuang-Lin; Zhu, Jia-Ying; Xu, Yu-Xing; Anderson, Alisha

2018-05-22

The functions of the Ionotropic Receptor (IR) family have been well studied in Drosophila melanogaster, but only limited information is available in Lepidoptera. Here, we conducted a large-scale genome-wide analysis of the IR gene repertoire in 13 moths and 16 butterflies. Combining a homology-based approach and manual efforts, totally 996 IR candidates are identified including 31 pseudogenes and 825 full-length sequences, representing the most current comprehensive annotation in lepidopteran species. The phylogeny, expression and sequence characteristics classify Lepidoptera IRs into three sub-families: antennal IRs (A-IRs), divergent IRs (D-IRs) and Lepidoptera-specific IRs (LS-IRs), which is distinct from the case of Drosophila IRs. In comparison to LS-IRs and D-IRs, A-IRs members share a higher degree of protein identity and are distinguished into 16 orthologous groups in the phylogeny, showing conservation of gene structure. Analysis of selective forces on 27 orthologous groups reveals that these lepidopteran IRs have evolved under strong purifying selection (dN/dS≪1). Most notably, lineage-specific gene duplications that contribute primarily to gene number variations across Lepidoptera not only exist in D-IRs, but are present in the two other sub-families including members of IR41a, 76b, 87a, 100a and 100b. Expression profiling analysis reveals that over 80% (21/26) of Helicoverpa armigera A-IRs are expressed more highly in antennae of adults or larvae than other tissues, consistent with its proposed function in olfaction. However, some are also detected in taste organs like proboscises and legs. These results suggest that some A-IRs in H. armigera likely bear a dual function with their involvement in olfaction and gustation. Results from mating experiments show that two HarmIRs (IR1.2 and IR75d) expression is significantly up-regulated in antennae of mated female moths. However, no expression difference is observed between unmated female and male adults, suggesting an association with female host-searching behaviors. Our current study has greatly extended the IR gene repertoire resource in Lepidoptera, and more importantly, identifies potential IR candidates for olfactory, gustatory and oviposition behaviors in the cotton bollworm. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Sequence analysis of ORF IV RTBV isolated from tungro infected Oryza sativa L. cv Ciherang

NASA Astrophysics Data System (ADS)

Hastilestari, Bernadetta Rina; Astuti, Dwi; Estiati, Amy; Nugroho, Satya

2015-09-01

The Effort to increase rice production is often constrained by pest and disease such as Tungro. The Tungro disease is caused by the joint infection with two dissimilar viruses; a bacil-form-DNA virus, the Rice tungro bacilliform virus(RTBV) and the spherical RNA virus, Rice tungro spherical virus (RTSV) and transmitted by Green leafhopper (Nephotettix virescens). The symptom of disease is caused by the presence of RTBV. The genome of RTBV consists of four Open reading frames (ORFs) which encode functional proteins. Of the four, ORF IV is unique because it exists only in RTBV. The most efficient method of generating disease resistance plants is to look for natural sources of resistance genes in wild or germplasm and then transfer the gene and the accompanying resistance in cultivated crop varieties. The aim of this study is, therefore, to isolate and analyze of 1170 bp gene of ORF 4 of Tungro virus isolated from an Indonesian rice cultivar, Ciherang (Oryza sativa L. cv Indica). DNA sequencing analysis using BLAST showed 94% similarity with the reference sequence gen bank Acc.M65026.1. The comparisons and mutation analysis of DNA sequences were discussed in this research.

cDNA cloning and heterologous expression of a wheat proteinase inhibitor of subtilisin and chymotrypsin (WSCI) that interferes with digestive enzymes of insect pests.

PubMed

Di Gennaro, Simone; Ficca, Anna G; Panichi, Daniela; Poerio, Elia

2005-04-01

A cDNA encoding the proteinase inhibitor WSCI (wheat subtilisin/chymotrypsin inhibitor) was isolated by RT-PCR. Degenerate oligonucleotide primers were designed based on the amino acid sequence of WSCI and on the nucleotide sequence of the two homologous inhibitors (CI-2A and CI-2B) isolated from barley. For large-scale production, wsci cDNA was cloned into the E. coli vector pGEX-2T. The fusion protein GST-WSCI was efficiently produced in the bacterial expression system and, as the native inhibitor, was capable of inhibiting bacterial subtilisin, mammalian chymotrypsins and chymotrypsin-like activities present in crude extracts of a number of insect larvae ( Helicoverpa armigera , Plodia interpunctella and Tenebrio molitor ). The recombinant protein produced was also able to interfere with chymotrypsin-like activity isolated from immature wheat caryopses. These findings support a physiological role for this inhibitor during grain maturation.

Blended Refuge and Insect Resistance Management for Insecticidal Corn

PubMed Central

Crespo, Andre L B; Pan, Zaiqi; Crain, Philip R; Thompson, Stephen D; Pilcher, Clinton D; Sethi, Amit

2018-01-01

Abstract In this review, we evaluate the intentional mixing or blending of insecticidal seed with refuge seed for managing resistance by insects to insecticidal corn (Zea mays). We first describe the pest biology and farming practices that will contribute to weighing trade-offs between using block refuges and blended refuges. Case studies are presented to demonstrate how the trade-offs will differ in different systems. We compare biological aspects of several abstract models to guide the reader through the history of modeling, which has played a key role in the promotion or denigration of blending in various scientific debates about insect resistance management for insecticidal crops. We conclude that the use of blended refuge should be considered on a case-by-case basis after evaluation of insect biology, environment, and farmer behavior. For Diabrotica virgifera virgifera, Ostrinia nubilalis, and Helicoverpa zea in the United States, blended refuge provides similar, if not longer, delays in the evolution of resistance compared to separate block refuges. PMID:29220481

Expression of a maize Myb transcription factor driven by a putative silk-specific promoter significantly enhances resistance to Helicoverpa zea in transgenic maize.

PubMed

Johnson, Eric T; Berhow, Mark A; Dowd, Patrick F

2007-04-18

Hi II maize (Zea mays) plants were engineered to express maize p1 cDNA, a Myb transcription factor, controlled by a putative silk specific promoter, for secondary metabolite production and corn earworm resistance. Transgene expression did not enhance silk color, but about half of the transformed plant silks displayed browning when cut, which indicated the presence of p1-produced secondary metabolites. Levels of maysin, a secondary metabolite with insect toxicity, were highest in newly emerged browning silks. The insect resistance of transgenic silks was also highest at emergence, regardless of maysin levels, which suggests that other unidentified p1-induced molecules likely contributed to larval mortality. Mean survivor weights of corn earworm larvae fed mature browning transgenic silks were significantly lower than weights of those fed mature nonbrowning transgenic silks. Some transgenic pericarps browned with drying and contained similar molecules found in pericarps expressing a dominant p1 allele, suggesting that the promoter may not be silk-specific.

Reduced plant nutrition under elevated CO2 depresses the immunocompetence of cotton bollworm against its endoparasite

NASA Astrophysics Data System (ADS)

Yin, Jin; Sun, Yucheng; Ge, Feng

2014-04-01

Estimating the immunocompetence of herbivore insects under elevated CO2 is an important step in understanding the effects of elevated CO2 on crop-herbivore-natural enemy interactions. Current study determined the effect of elevated CO2 on the immune response of Helicoverpa armigera against its parasitoid Microplitis mediator. H. armigera were reared in growth chambers with ambient or elevated CO2, and fed wheat grown in the concentration of CO2 corresponding to their treatment levels. Our results showed that elevated CO2 decreases the nutritional quality of wheat, and reduces the total hemocyte counts and impairs the capacity of hemocyte spreading of hemolymph of cotton bollworm larvae, fed wheat grown in the elevated CO2, against its parasitoid; however, this effect was insufficient to change the development and parasitism traits of M. mediator. Our results suggested that lower plant nutritional quality under elevated CO2 could decrease the immune response of herbivorous insects against their parasitoid natural enemies.

Analysis of variation in virulence of Beauveria bassiana against insect pests of pigeonpea using qPCR.

PubMed

Senthilraja, Govindasamy; Anand, Theerthagiri; Mohankumar, Subbarayalu; Raguchander, Thiruvengadam; Samiyappan, Ramasamy

2018-03-01

Beauveria bassiana is a broad spectrum microbial bioagent used for the control of agriculturally important insect pests. However, in our experiments, two virulent isolates of B. bassiana (B2 and B10) showed specific preference toward Maruca vitrata and Helicoverpa armigera of pigeonpea. To better understand this feature, we developed a qPCR assay to quantify the chitinase (virulence factor) of B. bassiana during the infection process. Isolates of B. bassiana were grown on insect cuticle amended medium and minimal medium (without insect cuticle) to assess the induction of chitinase. Our results revealed a positive correlation between expression of chitinase by B. bassiana and the substrates (with or without cuticles of M. vitrata and H. armigera) used. This study showcases the methodology to quantify the chitinase and analysis of variation in virulence of B. bassiana (B2 and B10) against M. vitrata and H. armigera. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Jasmonate response decay and defense metabolite accumulation contributes to age-regulated dynamics of plant insect resistance

PubMed Central

Mao, Ying-Bo; Liu, Yao-Qian; Chen, Dian-Yang; Chen, Fang-Yan; Fang, Xin; Hong, Gao-Jie; Wang, Ling-Jian; Wang, Jia-Wei; Chen, Xiao-Ya

2017-01-01

Immunity deteriorates with age in animals but comparatively little is known about the temporal regulation of plant resistance to herbivores. The phytohormone jasmonate (JA) is a key regulator of plant insect defense. Here, we show that the JA response decays progressively in Arabidopsis. We show that this decay is regulated by the miR156-targeted SQUAMOSA PROMOTER BINDING PROTEIN-LIKE9 (SPL9) group of proteins, which can interact with JA ZIM-domain (JAZ) proteins, including JAZ3. As SPL9 levels gradually increase, JAZ3 accumulates and the JA response is attenuated. We provide evidence that this pathway contributes to insect resistance in young plants. Interestingly however, despite the decay in JA response, older plants are still comparatively more resistant to both the lepidopteran generalist Helicoverpa armigera and the specialist Plutella xylostella, along with increased accumulation of glucosinolates. We propose a model whereby constitutive accumulation of defense compounds plays a role in compensating for age-related JA-response attenuation during plant maturation. PMID:28067238

Identification and characterization of aldehyde oxidases (AOXs) in the cotton bollworm

NASA Astrophysics Data System (ADS)

Xu, Wei; Liao, Yalin

2017-12-01

Aldehyde oxidases (AOXs) are a family of metabolic enzymes that oxidize aldehydes into carboxylic acids; therefore, they play critical roles in detoxification and degradation of chemicals. By using transcriptomic and genomic approaches, we successfully identified six putative AOX genes (HarmAOX1-6) from cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). In silico expression profile, reverse transcription (RT)-PCR, and quantitative PCR (qPCR) analyses showed that HarmAOX1 is highly expressed in adult antennae, tarsi, and larval mouthparts, so they may play an important role in degrading plant-derived compounds. HarmAOX2 is highly and specifically expressed in adult antennae, suggesting a candidate pheromone-degrading enzyme (PDE) to inactivate the sex pheromone components (Z)-11-hexadecenal and (Z)-9-hexadecenal. RNA sequencing data further demonstrated that a number of host plants they feed on could significantly upregulate the expression levels of HarmAOX1 in larvae. This study improves our understanding of insect aldehyde oxidases and insect-plant interactions.

Nutrition affects insect susceptibility to Bt toxins

NASA Astrophysics Data System (ADS)

Deans, Carrie A.; Behmer, Spencer T.; Tessnow, Ashley E.; Tamez-Guerra, Patricia; Pusztai-Carey, Marianne; Sword, Gregory A.

2017-01-01

Pesticide resistance represents a major challenge to global food production. The spread of resistance alleles is the primary explanation for observations of reduced pesticide efficacy over time, but the potential for gene-by-environment interactions (plasticity) to mediate susceptibility has largely been overlooked. Here we show that nutrition is an environmental factor that affects susceptibility to Bt toxins. Protein and carbohydrates are two key macronutrients for insect herbivores, and the polyphagous pest Helicoverpa zea self-selects and performs best on diets that are protein-biased relative to carbohydrates. Despite this, most Bt bioassays employ carbohydrate-biased rearing diets. This study explored the effect of diet protein-carbohydrate content on H. zea susceptibility to Cry1Ac, a common Bt endotoxin. We detected a 100-fold increase in LC50 for larvae on optimal versus carbohydrate-biased diets, and significant diet-mediated variation in survival and performance when challenged with Cry1Ac. Our results suggest that Bt resistance bioassays that use ecologically- and physiologically-mismatched diets over-estimate susceptibility and under-estimate resistance.

A Regulatory Pathway, Ecdysone-Transcription Factor Relish-Cathepsin L, Is Involved in Insect Fat Body Dissociation

PubMed Central

Zhang, Yao; Lu, Yu-Xuan; Liu, Jian; Yang, Cui; Feng, Qi-Li; Xu, Wei-Hua

2013-01-01

Insect fat body is the organ for intermediary metabolism, comparable to vertebrate liver and adipose tissue. Larval fat body is disintegrated to individual fat body cells and then adult fat body is remodeled at the pupal stage. However, little is known about the dissociation mechanism. We find that the moth Helicoverpa armigera cathepsin L (Har-CL) is expressed heavily in the fat body and is released from fat body cells into the extracellular matrix. The inhibitor and RNAi experiments demonstrate that Har-CL functions in the fat body dissociation in H. armigera. Further, a nuclear protein is identified to be transcription factor Har-Relish, which was found in insect immune response and specifically binds to the promoter of Har-CL gene to regulate its activity. Har-Relish also responds to the steroid hormone ecdysone. Thus, the dissociation of the larval fat body is involved in the hormone (ecdysone)-transcription factor (Relish)-target gene (cathepsin L) regulatory pathway. PMID:23459255

A Home-Made Trap Baited With Sex Pheromone for Monitoring Spodoptera Frugiperda Males (Lepidoptera: Noctuidae) in Corn crops in Mexico.

PubMed

Malo, Edi A; Cruz-Esteban, Samuel; González, Francisco J; Rojas, Julio C

2018-05-15

Fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), populations are monitored with a variety of commercial sex pheromone-baited traps. However, a number of trap-related variables may affect the number of FAW males captured. In this study, we tested the effect of trap design, trap size, and trap color for monitoring FAW males in corn crops in Mexico. We found that plastic jug trap (a home-made trap), captured significantly more FAW males than a commercial trap (Scentry Heliothis) and water bottle trap (another home-made trap). We also found that size of plastic jug traps (3.78, 10, or 20 liters) did not affect the captures of FAW males. Our results indicated that plastic yellow jug traps captured significantly more males than blue and black traps. Plastic jug white, red, and green traps captured a similar number of FAW males than plastic jug yellow, blue, and black traps. Plastic jug blue, white, and yellow traps captured more nontarget insects compared to black traps. The number of nontarget insects captured by green and red traps was similar and not significantly different to that caught by blue, white, yellow, and black traps. Traps captured more individuals from Diptera than Coleoptera and Hymenoptera. Overall, the results suggest that yellow plastic jug may be used for monitoring FAW males in corn and sorghum crops in Mexico.

Wound and methyl jasmonate induced pigeon pea defensive proteinase inhibitor has potency to inhibit insect digestive proteinases.

PubMed

Lomate, Purushottam R; Hivrale, Vandana K

2012-08-01

Wounding of plants by chewing insects or other damage induces the synthesis of defensive proteinase inhibitors (PI) in both wounded and distal unwounded leaves. In the present paper we report the characterization of inducible defensive PI from pigeon pea (Cajanus cajan) and its in vitro interaction with Helicoverpa armigera gut proteinases (HGP). We found that PI activity was induced in local as well as systemic leaves of pigeon pea by the wounding and methyl jasmonate (MeJA) application. Consistent induction of PI was observed in two wild cultivars of pigeon pea at various growth stages. The estimated molecular weight of inducible PI was ~16.5 kDa. Electrophoretic analysis and enzyme assays revealed that the induced PI significantly inhibited total gut proteinase as well as trypsin-like activity from the midgut of H. armigera. The induced PI was found to be inhibitor of trypsin as well as chymotrypsin. Study could be important to know the further roles of defensive PIs. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Evaluation of Nostoc Strain ATCC 53789 as a Potential Source of Natural Pesticides

PubMed Central

Biondi, Natascia; Piccardi, Raffaella; Margheri, M. Cristina; Rodolfi, Liliana; Smith, Geoffrey D.; Tredici, Mario R.

2004-01-01

The cyanobacterium Nostoc strain ATCC 53789, a known cryptophycin producer, was tested for its potential as a source of natural pesticides. The antibacterial, antifungal, insecticidal, nematocidal, and cytotoxic activities of methanolic extracts of the cyanobacterium were evaluated. Among the target organisms, nine fungi (Armillaria sp., Fusarium oxysporum f. sp. melonis, Penicillium expansum, Phytophthora cambivora, P. cinnamomi, Rhizoctonia solani, Rosellinia, sp., Sclerotinia sclerotiorum, and Verticillium albo-atrum) were growth inhibited and one insect (Helicoverpa armigera) was killed by the extract, as well as the two model organisms for nematocidal (Caenorhabditis elegans) and cytotoxic (Artemia salina) activity. No antibacterial activity was detected. The antifungal activity against S. sclerotiorum was further studied with both extracts and biomass of the cyanobacterium in a system involving tomato as a host plant. Finally, the herbicidal activity of Nostoc strain ATCC 53789 was evaluated against a grass mixture. To fully exploit the potential of this cyanobacterium in agriculture as a source of pesticides, suitable application methods to overcome its toxicity toward plants and nontarget organisms must be developed. PMID:15184126

The Expression of Three Opsin Genes from the Compound Eye of Helicoverpa armigera (Lepidoptera: Noctuidae) Is Regulated by a Circadian Clock, Light Conditions and Nutritional Status

PubMed Central

Yan, Shuo; Zhu, Jialin; Zhu, Weilong; Zhang, Xinfang; Li, Zhen; Liu, Xiaoxia; Zhang, Qingwen

2014-01-01

Visual genes may become inactive in species that inhabit poor light environments, and the function and regulation of opsin components in nocturnal moths are interesting topics. In this study, we cloned the ultraviolet (UV), blue (BL) and long-wavelength-sensitive (LW) opsin genes from the compound eye of the cotton bollworm and then measured their mRNA levels using quantitative real-time PCR. The mRNA levels fluctuated over a daily cycle, which might be an adaptation of a nocturnal lifestyle, and were dependent on a circadian clock. Cycling of opsin mRNA levels was disturbed by constant light or constant darkness, and the UV opsin gene was up-regulated after light exposure. Furthermore, the opsin genes tended to be down-regulated upon starvation. Thus, this study illustrates that opsin gene expression is determined by multiple endogenous and exogenous factors and is adapted to the need for nocturnal vision, suggesting that color vision may play an important role in the sensory ecology of nocturnal moths. PMID:25353953

How dietary plant nectar affects the survival, growth, and fecundity of a cursorial spider Cheiracanthium inclusum (Araneae: Miturgidae).

PubMed

Taylor, R M; Pfannenstiel, R S

2009-10-01

We measured the effects of plant nectar consumption on Cheiracanthium inclusum (Hentz) (Miturgidae), an agriculturally important spider. Newly emerged spiderlings were reared on the eggs of Helicoverpa zea (Boddie) at four prey densities, 1, 5, 25, or 125 eggs, three times a week, with or without nectar. Nectar came from the extrafloral nectaries of Indian almond, Terminalia cattapa L. (Combretaceae). The addition of nectar to prey (1) allowed spiderlings on the 1-egg diet to survive longer and molt many more times; (2) allowed virtually all of the spiderlings on the 5-egg diet to become small adults and 50% to mate and reproduce versus those without nectar, none of which matured to adulthood; and (3) increased fecundity of females on 5-egg and 25-egg diets to the level of females fed five times the amount of prey. These results show that spiders that feed on nectar increase their fitness with increased survival, growth, and fecundity, particularly when density of prey is inadequate or marginal.

A novel totivirus-like virus isolated from bat guano.

PubMed

Yang, Xinglou; Zhang, Yunzhi; Ge, Xingyi; Yuan, Junfa; Shi, Zhengli

2012-06-01

Previous metagenomic analysis indicated that numerous insect viruses exist in bat guano. In this study, we isolated a novel double-stranded RNA virus, a tentative member of the family Totiviridae, designated Tianjin totivirus (ToV-TJ), from bat feces. The virus is an icosahedral particle with a diameter of 40-43 nm, and it causes cytopathic effect in Sf9, Hz, and C6/36 cell lines. Full-length genomic sequence analysis showed that ToV-TJ shares high similarity with the totivirus OMRV-AK4, which was recently isolated from mosquitoes in Japan. The full-length genome of the ToV-TJ was 7611 bp and contained two predicted non-overlapping open reading frames (ORFs): ORF1, encoding the capsid protein (CP), and ORF2, encoding an RNA-dependent RNA polymerase. Bioassay of ToV-TJ by feeding on the larvae of Spodoptera exigua and Helicoverpa armigera (Hubner) suggests that this virus is not infectious for these two larvae in vivo. Sequences similar to that of ToV-TJ have been detected in bat feces sampled in Yunnan and Hainan Provinces, suggesting that this virus is widely distributed.

Dormancy cues alter insect temperature-size relationships.

PubMed

Clemmensen, Sharon F; Hahn, Daniel A

2015-01-01

Developmental temperatures can have dramatic effects on body size in ectotherms. Thermal plasticity in body size is often viewed in the context of seasonality, but the role of seasonal dormancy responses in generating temperature-size relationships is underappreciated. We used the moth Helicoverpa zea (corn earworm) to examine how photoperiodic seasonal dormancy programming for pupal diapause affects the temperature-size relationship. Specifically, we partition out the contributions of somatic growth versus nutrient storage as fat to the thermal reaction norm for size. With increasing temperature from 16 °C to 20 °C, dormant pupae were both overall larger and progressively fatter than non-dormant pupae. This body mass response is likely driven by concurrent increases in food consumption and longer development times as temperatures increase. Our results demonstrate that seasonal photoperiodic cues can alter temperature-size relationships during pre-dormancy development. For biologists interested in seasonal effects on temperature-size relationships, our results suggest that the key to fully understanding these relationships may lie in integrating multiple seasonal cues and multiple aspects of body size and composition in a nutrient-allocation framework.

Compatibility of garlic (Allium sativum L.) leaf agglutinin and Cry1Ac δ-endotoxin for gene pyramiding.

PubMed

Upadhyay, Santosh Kumar; Singh, Seema; Chandrashekar, Krishnappa; Tuli, Rakesh; Singh, Pradhyumna Kumar

2012-03-01

δ-Endotoxins produced by Bacillus thuringiensis (Bt) have been used as bio-pesticides for the control of lepidopteran insect pests. Garlic (Allium sativum L.) leaf agglutinin (ASAL), being toxic to several sap-sucking pests and some lepidopteran pests, may be a good candidate for pyramiding with δ-endotoxins in transgenic plants for enhancing the range of resistance to insect pests. Since ASAL shares the midgut receptors with Cry1Ac in Helicoverpa armigera, there is possibility of antagonism in their toxicity. Our study demonstrated that ASAL increased the toxicity of Cry1Ac against H. armigera while Cry1Ac did not alter the toxicity of ASAL against cotton aphids. The two toxins interacted and increased binding of each other to brush border membrane vesicle (BBMV) proteins and to the two important receptors, alkaline phosphatase (ALP) and aminopeptidase N (APN). The results indicated that the toxins had different binding sites on the ALP and APN but influenced mutual binding. We conclude that ASAL can be safely employed with Cry1Ac for developing transgenic crops for wider insect resistance.

Tradeoff between reproduction and resistance evolution to Bt-toxin in Helicoverpa armigera: regulated by vitellogenin gene expression.

PubMed

Zhang, W N; Xiao, H J; Liang, G M; Guo, Y Y; Wu, K M

2014-08-01

Evolution of resistance to insecticides usually has fitness tradeoffs associated with adaptation to the stress. The basic regulation mechanism of tradeoff between reproduction and resistance evolution to Bacillus thuringiensis (Bt) toxin in the cotton bollworm, Helicoverpa armigera (Ha), based on the vitellogenin (Vg) gene expression was analyzed here. The full-length cDNA of the Vg gene HaVg (JX504706) was cloned and identified. HaVg has 5704 base pairs (bp) with an open reading frame (ORF) of 5265 bp, which encoded 1756 amino acid protein with a predicted molecular mass of 197.28 kDa and a proposed isoelectric point of 8.74. Sequence alignment analysis indicated that the amino acid sequence of HaVg contained all of the conserved domains detected in the Vgs of the other insects and had a high similarity with the Vgs of the Lepidoptera insects, especially Noctuidae. The resistance level to Cry1Ac Bt toxin and relative HaVg mRNA expression levels among the following four groups: Cry1Ac-susceptible strain (96S), Cry1Ac-resistant strain fed on artificial diet with Bt toxin for 135 generations (BtR stands for the Cry1Ac Bt resistance), progeny of the Cry1Ac-resistant strain with a non-Bt-toxin artificial diet for 38 generations (CK1) and the direct descendants of the 135th-generation resistant larvae which were fed on an artificial diet without the Cry1Ac protein (CK2) were analyzed. Compared with the 96S strain, the resistance ratios of the BtR strain, the CK1 strain and the CK2 strain were 2917.15-, 2.15- and 2037.67-fold, respectively. The maximum relative HaVg mRNA expression levels of the BtR strain were approximately 50% less than that of the 96S strain, and the coming of maximum expression was delayed for approximately 4 days. The overall trend of the HaVg mRNA expression levels in the CK1 strain was similar to that in the 96S strain, and the overall trend of the HaVg mRNA expression levels in the CK2 strain was similar to that in the BtR strain. Our results suggest that the changes in reproduction due to the Bt-toxin resistance evolution in the BtR strain may be regulated by the Vg gene expression. The down-regulation of HaVg at the early stages resulted in a period of delayed reproduction and decreased fecundity in the BtR strain. This performance disappeared when the Bt-toxin selection pressure was lost.

Organochlorine residues and eggshell thinning in anhingas and waders

USGS Publications Warehouse

Ohlendorf, Harry M.; Klaas, Erwin E.; Kaiser, T. Earl; Southern, William E.

1978-01-01

Residues of organochlorine compounds occur commonly in environmental samples and have been associated with adverse effects in numerous avian species (Cooke 1973; L. F. Stickel 1973; W. H. Stickel 1975; Ohlendorf et al. 1977; H. M. Ohlendorf, R. W. Risebrough, and K. Vermeer, unpublished manuscript). The affected species are usually terminal consumers, generally those feeding on aquatic organisms (primarily fish) or birds. Brown Pelicans (Pelecanus occidentalis), Double-crested Cormorants (Phalacrocorax auritus), and certain herons are among the species that have exhibited shell thinning in some regions (see Ohlendorf et al. 1977 for review). In 1972, we began a study to determine: (1) geographic differences in the occurrence of environmental pollutants in Anhingas (Anhinga anhinga) and waders in the eastern United States; (2) differences in environmental pollutant levels among those species nesting at the same localities; and (3) whether eggshell thickness had changed since the widespread use of organochlorine pesticides began in the mid-1940's. The wader species included in our study were: Great Blue Heron (Ardea herodias), Green Heron (Butorides virescens), Little Blue Heron (Florida caerulea), Cattle Egret (Bubulcus ibis), Reddish Egret (Dichromanassa rufescens), Great Egret (Casmerodius albus), Snowy Egret (Egretta thula), Louisiana Heron (Hydranassa tricolor), Black-crowned Night Heron (Nycticorax nycticorax), Yellow-crowned Night Heron (Nyctanassa violacea), Least Bittern (Ixobrychus exilis), American Bittern (Botaurus lentiginosus), Wood Stork (Mycteria americana), Glossy Ibis (Plegadis falcinellus), White Ibis (Eudocimus albus), and Roseate Spoonbill (Ajaia ajaja).

Risky business: Site selection by Acadian Flycatchers under threat of nest predation and brood parasitism

USGS Publications Warehouse

HazIer, K.R.; Cooper, R.J.; Twedt, D.J.

2006-01-01

Habitat quality is determined not only by habitat structure and the availability of resources, but also by competitors, cooperators, predators, and parasites. We hypothesized that, for passerines, minimizing risk from avian nest predators and brood parasites is an important factor in selecting a breeding site. Through the early part of two breeding seasons, we spot-mapped locations of Acadian Flycatchers (Empidonax virescens, territory selectors), Red-bellied Woodpeckers (Melanerpes carolinus, nest predators) and Brown-headed Cowbirds (Molothrus ater, brood parasites) in a 56-ha study area within an extensive bottomland hardwood forest. We were thereby able to determine the order of flycatcher territory settlement and nest initiation in relation to risk of predation and parasitism, while accounting for habitat structure. Male settlement was influenced by both habitat structure and risk avoidance. However, risk trom woodpeckers was relatively more important in the first season and risk from cowbirds in the second, evidently due to differences in the relative abundance of predator and brood-parasite in each year. For male flycatchers, settlement choices appear to be flexible in the face of changing 'risk landscapes.' For females, habitat structure was the most important predictor of nest site selection. Even so, there was evidence that females avoided cowbirds. Surprisingly, nest site selection was positively associated with woodpecker abundance in the first season when woodpeckers were present in greater numbers. Possible explanations for this contradictory result are discussed.

Evolutionary stability of mutualism: interspecific population regulation as an evolutionarily stable strategy.

PubMed

Holland, J Nathaniel; DeAngelis, Donald L; Schultz, Stewart T

2004-09-07

Interspecific mutualisms are often vulnerable to instability because low benefit : cost ratios can rapidly lead to extinction or to the conversion of mutualism to parasite-host or predator-prey interactions. We hypothesize that the evolutionary stability of mutualism can depend on how benefits and costs to one mutualist vary with the population density of its partner, and that stability can be maintained if a mutualist can influence demographic rates and regulate the population density of its partner. We test this hypothesis in a model of mutualism with key features of senita cactus (Pachycereus schottii)-senita moth (Upiga virescens) interactions, in which benefits of pollination and costs of larval seed consumption to plant fitness depend on pollinator density. We show that plants can maximize their fitness by allocating resources to the production of excess flowers at the expense of fruit. Fruit abortion resulting from excess flower production reduces pre-adult survival of the pollinating seed-consumer, and maintains its density beneath a threshold that would destabilize the mutualism. Such a strategy of excess flower production and fruit abortion is convergent and evolutionarily stable against invasion by cheater plants that produce few flowers and abort few to no fruit. This novel mechanism of achieving evolutionarily stable mutualism, namely interspecific population regulation, is qualitatively different from other mechanisms invoking partner choice or selective rewards, and may be a general process that helps to preserve mutualistic interactions in nature.

Building hierarchical models of avian distributions for the State of Georgia

USGS Publications Warehouse

Howell, J.E.; Peterson, J.T.; Conroy, M.J.

2008-01-01

To predict the distributions of breeding birds in the state of Georgia, USA, we built hierarchical models consisting of 4 levels of nested mapping units of decreasing area: 90,000 ha, 3,600 ha, 144 ha, and 5.76 ha. We used the Partners in Flight database of point counts to generate presence and absence data at locations across the state of Georgia for 9 avian species: Acadian flycatcher (Empidonax virescens), brownheaded nuthatch (Sitta pusilla), Carolina wren (Thryothorus ludovicianus), indigo bunting (Passerina cyanea), northern cardinal (Cardinalis cardinalis), prairie warbler (Dendroica discolor), yellow-billed cuckoo (Coccyxus americanus), white-eyed vireo (Vireo griseus), and wood thrush (Hylocichla mustelina). At each location, we estimated hierarchical-level-specific habitat measurements using the Georgia GAP Analysis18 class land cover and other Geographic Information System sources. We created candidate, species-specific occupancy models based on previously reported relationships, and fit these using Markov chain Monte Carlo procedures implemented in OpenBugs. We then created a confidence model set for each species based on Akaike's Information Criterion. We found hierarchical habitat relationships for all species. Three-fold cross-validation estimates of model accuracy indicated an average overall correct classification rate of 60.5%. Comparisons with existing Georgia GAP Analysis models indicated that our models were more accurate overall. Our results provide guidance to wildlife scientists and managers seeking predict avian occurrence as a function of local and landscape-level habitat attributes.

Weed manipulation for insect pest management in corn

NASA Astrophysics Data System (ADS)

Altieri, M. A.; Whitcomb, W. H.

1980-11-01

Populations of insect pests and associated predaceous arthropods were sampled by direct observation and other relative methods in simple and diversified corn habitats at two sites in north Florida during 1978 and 1979. Through various cultural manipulations, characteristic weed communities were established selectively in alternate rows within corn plots. Fall armyworm ( Spodoptera frugiperda J. E. Smith) incidence was consistently higher in the weed-free habitats than in the corn habitats containing natural weed complexes or selected weed associations. Corn earworm ( Heliothis zea Boddie) damage was similar in all weed-free and weedy treatments, suggesting that this insect is not affected greatly by weed diversity. Only the diversification of corn with a strip of soybean significantly reduced corn earworm damage. In one site, distance between plots was reduced. Because predators moved freely between habitats, it was difficult to identify between-treatment differences in the composition of predator communities. In the other site, increased distances between plots minimized such migrations, resulting in greater population densities and diversity of common foliage insect predators in the weed-manipulated corn systems than in the weed-free plots. Trophic relationships in the weedy habitats were more complex than food webs in monocultures. Predator diversity (measured as mean number of species per area) and predator density was higher in com plots surrounded by mature, complex vegetation than at those surrounded by annual crops. This suggests that diverse adjacent areas to crops provide refuge for predators, thus acting as colonization sources.

Bt Cry1Ie Toxin Does Not Impact the Survival and Pollen Consumption of Chinese Honey Bees, Apis cerana cerana (Hymenoptera, Apidae).

PubMed

Dai, Ping-Li; Jia, Hui-Ru; Jack, Cameron J; Geng, Li-Li; Liu, Feng; Hou, Chun-Sheng; Diao, Qing-Yun; Ellis, James D

2016-12-01

The cry1Ie gene may be a good candidate for the development of Bt maize because over-expression of Cry1Ie is highly toxic to Lepidopteran pests such as Heliothis armigera Hübner and Ostrinia furnacalis Guenée. The Bt cry1Ie gene also has no cross resistance with other insecticidal proteins such as Cry1Ab, Cry1Ac, Cry1Ah, or Cry1F. Chinese honey bees (Apis cerana cerana) are potentially exposed to insect-resistant genetically modified (IRGM) crops expressing Cry1Ie toxin via the collection of IRGM crop pollen. In this study, we tested whether Chinese honey bee workers are negatively affected by sugar syrup containing 20, 200, or 20,000 ng/ml Cry1Ie toxin and 48 ng/ml imidacloprid under controlled laboratory conditions. Our results demonstrated that the Cry1Ie toxin does not adversely impact survival and pollen consumption of Chinese honey bees. However, imidacloprid decreases Chinese honey bee survival and the total pollen consumption on the 5th, 6th, and 18th d of exposure. The described bioassay is suitable to assess the effects of GM expressed toxins against honey bee. © 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.

Molecular characterization of Bacillus thuringiensis isolated from diverse habitats of India.

PubMed

Patel, Ketan D; Chudasama, Chaitanyasinh J; Ingle, Sanjay S

2012-08-01

Bacillus thuringiensis (Bt) strains were isolated from 94 samples from different geographical regions. Novel types of crystalline inclusion bodies were observed from some of the isolates. Crystalline inclusions of bipyramidal, spherical and cuboidal morphology were found produced by most of the isolates. Isolate GS12 showed crystal on one side of spore while isolate GM108 formed crystals on both termini of spore. Isolate GN31 produced large sized bipyramidal crystals. SDS-PAGE analysis of the spore crystal suspension showed major protein bands in the range of 29 and 140 kDa. Two new serovars of Bt viz. GS4 and GN24 having H3abce and H3ab serotype respectively were isolated. Toxicity comparable to the reference strain Bacillus thuringiensis subs. kurstaki (Btk) HD-1 was observed for the isolates GM20, GM17 and MP3 against larvae of Helicoverpa armigera. Some of the isolates harboring cry genes like cry1Ac and cry2 did not show any toxicity towards H. armigera while most of the isolates were harboring cry1, cry1Ac and cry2 gene. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Marine-Natural-Product Development: First Discovery of Nortopsentin Alkaloids as Novel Antiviral, Anti-phytopathogenic-Fungus, and Insecticidal Agents.

PubMed

Ji, Xiaofei; Guo, Jincheng; Liu, Yuxiu; Lu, Aidang; Wang, Ziwen; Li, Yongqiang; Yang, Shaoxiang; Wang, Qingmin

2018-04-25

Nortopsentin alkaloids were found to have potent antiviral, anti-phytopathogenic-fungus, and insecticidal activities for the first time. Antiviral-activity tests revealed that these compounds were very sensitive to substituents, so a series of nortopsentin derivatives were designed, synthesized, and systematically evaluated for their antiviral activities against TMV, their fungicidal activities, and their insecticidal activities on the basis of a structural-diversity-derivation strategy. Compounds 2e (in vivo inactivation-, curative-, and protective-activity inhibitory rates of 50, 59, and 56%, respectively, at 500 μg/mL) and 2k (in vivo inactivation-, curative-, and protective-activity inhibitory rates of 60, 58, and 52%, respectively, at 500 μg/mL), with excellent antiviral activities and good physicochemical properties, emerged as new lead compounds for novel-antiviral-agent development. Further fungicidal-activity tests revealed that these alkaloids displayed broad-spectrum fungicidal activities. Compounds 2f, 2h, and 2j emerged as new lead compounds for antifungal-activity research. Additionally, all the compounds displayed good insecticidal activities against five kinds of insects, including Mythimna separate, Helicoverpa armigera, Ostrinia nubilalis, Plutella xylostella, and Culex pipiens pallens.

Quantitative trait loci and metabolic pathways

PubMed Central

McMullen, M. D.; Byrne, P. F.; Snook, M. E.; Wiseman, B. R.; Lee, E. A.; Widstrom, N. W.; Coe, E. H.

1998-01-01

The interpretation of quantitative trait locus (QTL) studies is limited by the lack of information on metabolic pathways leading to most economic traits. Inferences about the roles of the underlying genes with a pathway or the nature of their interaction with other loci are generally not possible. An exception is resistance to the corn earworm Helicoverpa zea (Boddie) in maize (Zea mays L.) because of maysin, a C-glycosyl flavone synthesized in silks via a branch of the well characterized flavonoid pathway. Our results using flavone synthesis as a model QTL system indicate: (i) the importance of regulatory loci as QTLs, (ii) the importance of interconnecting biochemical pathways on product levels, (iii) evidence for “channeling” of intermediates, allowing independent synthesis of related compounds, (iv) the utility of QTL analysis in clarifying the role of specific genes in a biochemical pathway, and (v) identification of a previously unknown locus on chromosome 9S affecting flavone level. A greater understanding of the genetic basis of maysin synthesis and associated corn earworm resistance should lead to improved breeding strategies. More broadly, the insights gained in relating a defined genetic and biochemical pathway affecting a quantitative trait should enhance interpretation of the biological basis of variation for other quantitative traits. PMID:9482823

Ignoring the irrelevant: auditory tolerance of audible but innocuous sounds in the bat-detecting ears of moths

NASA Astrophysics Data System (ADS)

Fullard, James H.; Ratcliffe, John M.; Jacobs, David S.

2008-03-01

Noctuid moths listen for the echolocation calls of hunting bats and respond to these predator cues with evasive flight. The African bollworm moth, Helicoverpa armigera, feeds at flowers near intensely singing cicadas, Platypleura capensis, yet does not avoid them. We determined that the moth can hear the cicada by observing that both of its auditory receptors (A1 and A2 cells) respond to the cicada’s song. The firing response of the A1 cell rapidly adapts to the song and develops spike periods in less than a second that are in excess of those reported to elicit avoidance flight to bats in earlier studies. The possibility also exists that for at least part of the day, sensory input in the form of olfaction or vision overrides the moth’s auditory responses. While auditory tolerance appears to allow H. armigera to exploit a food resource in close proximity to acoustic interference, it may render their hearing defence ineffective and make them vulnerable to predation by bats during the evening when cicadas continue to sing. Our study describes the first field observation of an eared insect ignoring audible but innocuous sounds.

Plant phenolics are detoxified by prophenoloxidase in the insect gut

PubMed Central

Wu, Kai; Zhang, Jie; Zhang, Qiaoli; Zhu, Shoulin; Shao, Qimiao; Clark, Kevin D.; Liu, Yining; Ling, Erjun

2015-01-01

Plant phenolics are a group of important secondary metabolites that are toxic to many animals and insects if ingested at high concentrations. Because most insects consume plant phenolics daily, they have likely evolved the capacity to detoxify these compounds. Here, we used Drosophila melanogaster, Bombyx mori and Helicoverpa armigera as models to study the metabolism of plant phenolics by prophenoloxidases. We found that insect foreguts release prophenoloxidases into the lumen, and that the survival of prophenoloxidase-deletion mutants was impaired when fed several plant phenolics and tea extracts. Using l-DOPA as a model substrate, biochemical assays in large Lepidopteran insects demonstrated that low levels of l-DOPA are rapidly metabolized into intermediates by phenoloxidases. Feeding with excess l-DOPA showed that the metabolic intermediate 5,6-dihydroxyindole reached the hindgut either by passing directly through the midgut, or by transport through the hemolymph. In the hindgut, 5,6-dihydroxyindole was further oxidized by prophenoloxidases. Intermediates exerted no toxicity in the hemocoel or midgut. These results show that plant phenolics are not toxic to insects unless prophenoloxidase genes are lost or the levels of phenolics exceed the catalytic activity of the gut prophenoloxidases. PMID:26592948

Emamectin, a novel insecticide for controlling field crop pests.

PubMed

Ishaaya, Isaac; Kontsedalov, Svetlana; Horowitz, A Rami

2002-11-01

Emamectin is a macrocyclic lactone insecticide with low toxicity to non-target organisms and the environment, and is considered an important component in pest-management programmes for controlling field crop pests. It is a powerful compound for controlling the cotton bollworm Helicoverpa armigera (Hübner). A spray concentration of 25 mg AI litre-1 in a cotton field resulted in over 90% suppression of H armigera larvae up to day 28 after treatment, while similar mortality of the Egyptian cotton leafworm Spodoptera littoralis Boisduval, under the same conditions, was maintained for 3 days only. Emamectin is a potent compound for controlling the western flower thrips Frankliniella occidentalis (Pergande) under both laboratory and field conditions and its activity on adults was over 10-fold greater than that of abamectin. Spray concentrations of 10 and 50 mg AI litre-1 in Ageratum houstonianum Mill flowers resulted in total suppression of adults up to day 11 and of larvae up to day 20 after treatment. Under standard laboratory conditions, emamectin exhibits a considerable activity on the whitefly Bemisia tabaci (Gennadius) and the leafminer Liriomyza huidobrensis (Blanchard). Further studies are required to evaluate its potential activity on the latter pests under field conditions.

Molecular characterization of nucleopolyhedrovirus of three lepidopteran pests using late expression factor-8 gene.

PubMed

Jose, Jency; Jalali, S K; Shivalingaswamy, T M; Kumar, N K Krishna; Bhatnagar, R; Bandyopadhyay, A

2013-06-01

A PCR based method for detection of viral DNA in nucleopolyhedrovirus of three lepidopterans, Spodoptera litura, Amsacta albistriga and Helicoverpa armigera, was developed by employing the late expression factor-8 (lef-8) gene of three NPV using specific primers. The amplicons of 689, 699 and 665 bp were amplified, respectively, and the nucleotide sequences were submitted to GenBank and the accession numbers were obtained. The sequences of lef-8 gene of S. litura NPV and H. armigera NPV matched with those of their respective references in the GenBank database, thereby confirming their identity, however, the sequence of A. albistriga NPV was the first sequence submitted to the GenBank database. The sequence similarity analysis between the three lef-8 gene of NPV sequenced in the present study revealed that there was no significant similarity between them, however A. albistriga NPV and S. litura NPV were found to be closely related. CLUSTAL alignment of the sequences generated revealed general relatedness among NPVs lef-8 gene. The study confirmed that lef-8 gene can be used for quick and correct discriminatory identification of insect viruses.

Pollen-mediated gene flow from transgenic cotton under greenhouse conditions is dependent on different pollinators

PubMed Central

Yan, Shuo; Zhu, Jialin; Zhu, Weilong; Li, Zhen; Shelton, Anthony M.; Luo, Junyu; Cui, Jinjie; Zhang, Qingwen; Liu, Xiaoxia

2015-01-01

With the large-scale release of genetically modified (GM) crops, there are ecological concerns on transgene movement from GM crops to non-GM counterparts and wild relatives. In this research, we conducted greenhouse experiments to measure pollen-mediated gene flow (PGF) in the absence and presence of pollinators (Bombus ignitus, Apis mellifera and Pieris rapae) in one GM cotton (resistant to the insect Helicoverpa armigera and the herbicide glyphosate) and two non-GM lines (Shiyuan321 and Hai7124) during 2012 and 2013. Our results revealed that: (1) PGF varied depending on the pollinator species, and was highest with B. ignitus (10.83%) and lowest with P. rapae (2.71%); (2) PGF with B. ignitus depended on the distance between GM and non-GM cottons; (3) total PGF to Shiyuan321 (8.61%) was higher than to Hai7124 (4.10%). To confirm gene flow, we tested hybrids carrying transgenes for their resistance to glyphosate and H. armigera, and most hybrids showed strong resistance to the herbicide and insect. Our research confirmed that PGF depended on pollinator species, distance between plants and the receptor plant. PMID:26525573

Replication of Syngrapha falcifera Multiple-Nuclear Polyhedrosis Virus-D in Different Insect Cells

NASA Astrophysics Data System (ADS)

Khalid Nessr Alhag, Sadeq; Xin, Peng Jian

Six insect cell lines were tested for susceptibility to Syngrapha falcifera multiple nucleocapsid nucleopolyhedrovirus-D (SfaMNPV-D) infection by use of a typical endpoint assay procedure. Cell lines from Trichoplusia ni (Tn5B1-4), (L105-clone), Spodoptera litura (SL-ZSU-1), Spodoptera frugiperda (IPLB-SF-21), Pieris rapaeb (Pr-E-HNU9) and Helicoverpa zea (BCIRL-HZ-AM1) in 96-well tissue culture plates were infected with dilutions of extra cellular virus suspensions of (SfaMNPV-D). Each cell/virus combination was incubated at temperatures 27°C and wells were scored for positive infection at 2 to 4 day intervals. The resulting data were analyzed by Reed and Muench method, providing virus titers for each combination of virus, cell line. The results were categorized by accuracy and by rapidity of maximum titer. Virus titer of Tn5B-4 was higher than other cell lines TCID50 8.7x108, the lowest level detected in infected was in (Pr-E-HNU9) cells TCID50 2.4x108. No Virions or polyhedral inclusion bodies were detected in infected SL-ZSU-1 cells.

Evolutionary stability of mutualism: interspecific population regulation as an evolutionarily stable strategy

USGS Publications Warehouse

Holland, J. Nathaniel; DeAngelis, Donald L.; Schultz, Stewart T.

2004-01-01

Interspecific mutualisms are often vulnerable to instability because low benefit : cost ratios can rapidly lead to extinction or to the conversion of mutualism to parasite–host or predator–prey interactions. We hypothesize that the evolutionary stability of mutualism can depend on how benefits and costs to one mutualist vary with the population density of its partner, and that stability can be maintained if a mutualist can influence demographic rates and regulate the population density of its partner. We test this hypothesis in a model of mutualism with key features of senita cactus (Pachycereus schottii) – senita moth (Upiga virescens) interactions, in which benefits of pollination and costs of larval seed consumption to plant fitness depend on pollinator density. We show that plants can maximize their fitness by allocating resources to the production of excess flowers at the expense of fruit. Fruit abortion resulting from excess flower production reduces pre–adult survival of the pollinating seed–consumer, and maintains its density beneath a threshold that would destabilize the mutualism. Such a strategy of excess flower production and fruit abortion is convergent and evolutionarily stable against invasion by cheater plants that produce few flowers and abort few to no fruit. This novel mechanism of achieving evolutionarily stable mutualism, namely interspecific population regulation, is qualitatively different from other mechanisms invoking partner choice or selective rewards, and may be a general process that helps to preserve mutualistic interactions in nature.

Length-Based Assessment of Coral Reef Fish Populations in the Main and Northwestern Hawaiian Islands

PubMed Central

Nadon, Marc O.; Ault, Jerald S.; Williams, Ivor D.; Smith, Steven G.; DiNardo, Gerard T.

2015-01-01

The coral reef fish community of Hawaii is composed of hundreds of species, supports a multimillion dollar fishing and tourism industry, and is of great cultural importance to the local population. However, a major stock assessment of Hawaiian coral reef fish populations has not yet been conducted. Here we used the robust indicator variable “average length in the exploited phase of the population (L¯)”, estimated from size composition data from commercial fisheries trip reports and fishery-independent diver surveys, to evaluate exploitation rates for 19 Hawaiian reef fishes. By and large, the average lengths obtained from diver surveys agreed well with those from commercial data. We used the estimated exploitation rates coupled with life history parameters synthesized from the literature to parameterize a numerical population model and generate stock sustainability metrics such as spawning potential ratios (SPR). We found good agreement between predicted average lengths in an unfished population (from our population model) and those observed from diver surveys in the largely unexploited Northwestern Hawaiian Islands. Of 19 exploited reef fish species assessed in the main Hawaiian Islands, 9 had SPRs close to or below the 30% overfishing threshold. In general, longer-lived species such as surgeonfishes, the redlip parrotfish (Scarus rubroviolaceus), and the gray snapper (Aprion virescens) had the lowest SPRs, while short-lived species such as goatfishes and jacks, as well as two invasive species (Lutjanus kasmira and Cephalopholis argus), had SPRs above the 30% threshold. PMID:26267473

Selectable antibiotic resistance marker gene-free transgenic rice harbouring the garlic leaf lectin gene exhibits resistance to sap-sucking planthoppers.

PubMed

Sengupta, Subhadipa; Chakraborti, Dipankar; Mondal, Hossain A; Das, Sampa

2010-03-01

Rice, the major food crop of world is severely affected by homopteran sucking pests. We introduced coding sequence of Allium sativum leaf agglutinin, ASAL, in rice cultivar IR64 to develop sustainable resistance against sap-sucking planthoppers as well as eliminated the selectable antibiotic-resistant marker gene hygromycin phosphotransferase (hpt) exploiting cre/lox site-specific recombination system. An expression vector was constructed containing the coding sequence of ASAL, a potent controlling agent against green leafhoppers (GLH, Nephotettix virescens) and brown planthopper (BPH, Nilaparvata lugens). The selectable marker (hpt) gene cassette was cloned within two lox sites of the same vector. Alongside, another vector was developed with chimeric cre recombinase gene cassette. Reciprocal crosses were performed between three single-copy T(0) plants with ASAL- lox-hpt-lox T-DNA and three single-copy T(0) plants with cre-bar T-DNA. Marker gene excisions were detected in T(1) hybrids through hygromycin sensitivity assay. Molecular analysis of T(1) plants exhibited 27.4% recombination efficiency. T(2) progenies of L03C04(1) hybrid parent showed 25% cre negative ASAL-expressing plants. Northern blot, western blot and ELISA showed significant level of ASAL expression in five marker-free T(2) progeny plants. In planta bioassay of GLH and BPH performed on these T(2) progenies exhibited radical reduction in survivability and fecundity compared with the untransformed control plants.

Wading birds as biological indicators 1975 colony survey

USGS Publications Warehouse

Custer, T.W.; Osborn, R.G.

1977-01-01

The suitability of wading birds (herons and their allies) as biological indicators in the coastal environment were studied in 1975 by 8 teams of investigators which located and censused 198 colonies along the Atlantic coast from Maine to Florida [USA]. Over 1/4 million breeding birds [Ardea herodias, Butorides virescens, Florida caerulea, Bubulcus ibis, Dichromanassa rufescens, Casmerodius albus, Egretta thula, Hydranassa tricolor, Nycticorax nycticorax, Nyctanassa violacea, Mycteria americana, Plegadis falcinellus, Eudocimus albus and Ajaia ajaja] were censused. The number of species in colonies ranged from 1-11. The number of 1- and 2-spp. colonies increased from Florida to Maine. Colony size decreased from Florida to Maine. Wading bird colony sites are generally active each year and the number of colonies may have recently increased in some areas of the coast. Species composition and total population of colonies fluctuate from year to year. The breeding population of wading birds was correlated with the area of coastal wetlands by state. Five teams of investigators studied the reproductive biology of 9 spp. in 13 colonies. Mean clutch size, the percentage of nests in which 1 or more eggs hatched and the overall percentage of eggs that hatched differed among colonies for some species, but no latitudinal gradient was found in any of these characteristics for any species. The use of wading birds to their full potential as biological indicators requires further exploration: survey and reproductive success methods need to be tested, the survey of colonies repeated, available historical information assembled and habitat requirements measured.

Genetic basis of multiple resistance to the brown planthopper (Nilaparvata lugens Stål) and the green rice leafhopper (Nephotettix cincticeps Uhler) in the rice cultivar ‘ASD7’ (Oryza sativa L. ssp. indica)

PubMed Central

Van Mai, Tan; Fujita, Daisuke; Matsumura, Masaya; Yoshimura, Atsushi; Yasui, Hideshi

2015-01-01

The rice cultivar ASD7 (Oryza sativa L. ssp. indica) is resistant to the brown planthopper (BPH; Nilaparvata lugens Stål) and the green leafhopper (Nephotettix virescens Distant). Here, we analyzed multiple genetic resistance to BPH and the green rice leafhopper (GRH; Nephotettix cincticeps Uhler). Using two independent F2 populations derived from a cross between ASD7 and Taichung 65 (Oryza sativa ssp. japonica), we detected two QTLs (qBPH6 and qBPH12) for resistance to BPH and one QTL (qGRH5) for resistance to GRH. Linkage analysis in BC2F3 populations revealed that qBPH12 controlled resistance to BPH and co-segregated with SSR markers RM28466 and RM7376 in plants homozygous for the ASD7 allele at qBPH6. Plants homozygous for the ASD7 alleles at both QTLs showed a much faster antibiosis response to BPH than plants homozygous at only one of these QTLs. It revealed that epistatic interaction between qBPH6 and qBPH12 is the basis of resistance to BPH in ASD7. In addition, qGRH5 controlled resistance to GRH and co-segregated with SSR markers RM6082 and RM3381. qGRH5 is identical to GRH1. Thus, we clarified the genetic basis of multiple resistance of ASD7 to BPH and GRH. PMID:26719745

Distribution of sterigmatocystin in filamentous fungi.

PubMed

Rank, Christian; Nielsen, Kristian F; Larsen, Thomas O; Varga, Janos; Samson, Rob A; Frisvad, Jens C

2011-01-01

During the last 50y, the carcinogenic mycotoxin sterigmatocystin (ST) has been reported in several phylogenetically and phenotypically different genera: Aschersonia, Aspergillus, Bipolaris, Botryotrichum, Chaetomium, Emericella, Eurotium, Farrowia, Fusarium, Humicola, Moelleriella, Monocillium and Podospora. We have reexamined all available strains of the original producers, in addition to ex type and further strains of each species reported to produce ST and the biosynthetically derived aflatoxins. We also screened strains of all available species in Penicillium and Aspergillus for ST and aflatoxin. Six new ST producing fungi were discovered: Aspergillus asperescens, Aspergillus aureolatus, Aspergillus eburneocremeus, Aspergillus protuberus, Aspergillus tardus, and Penicillium inflatum and one new aflatoxin producer: Aspergillus togoensis (=Stilbothamnium togoense). ST was confirmed in 23 Emericella, four Aspergillus, five Chaetomium, one Botryotrichum and one Humicola species grown on a selection of secondary metabolite inducing media, and using multiple detection methods: HPLC-UV/Vis DAD, - HRMS and - MS/MS. The immediate precursor for aflatoxin, O-methylsterigmatocystin was found in Chaetomium cellulolyticum, Chaetomium longicolleum, Chaetomium malaysiense and Chaetomium virescens, but aflatoxin was not detected from any Chaetomium species. In all 55 species, representing more than 11 clades throughout the Pezizomycotina, can be reliably claimed to be ST producers and 13 of these can also produce aflatoxins. It is not known yet whether the ST/aflatoxin pathway has been developed independently 11 times, or is the result of partial horizontal gene transfer. Copyright © 2011 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Quantitative trait loci for maysin synthesis in maize (Zea mays L.) lines selected for high silk maysin content.

PubMed

Meyer, J D F; Snook, M E; Houchins, K E; Rector, B G; Widstrom, N W; McMullen, M D

2007-06-01

Maysin is a naturally occurring C-glycosyl flavone found in maize (Zea mays L.) silk tissue that confers resistance to corn earworm (Helicoverpa zea, Boddie). Recently, two new maize populations were derived for high silk maysin. The two populations were named the exotic populations of maize (EPM) and the southern inbreds of maize (SIM). Quantitative trait locus (QTL) analysis was employed to determine which loci were responsible for elevated maysin levels in inbred lines derived from the EPM and SIM populations. The candidate genes consistent with QTL position included the p (pericarp color), c2 (colorless2), whp1 (white pollen1) and in1 (intensifier1) loci. The role of these loci in controlling high maysin levels in silks was tested by expression analysis and use of the loci as genetic markers onto the QTL populations. These studies support p, c2 and whp1, but not in1, as loci controlling maysin. Through this study, we determined that the p locus regulates whp1 transcription and that increased maysin in these inbred lines was primarily due to alleles at both structural and regulatory loci promoting increased flux through the flavone pathway by increasing chalcone synthase activity.

Adenylate kinase 2 (AK2) promotes cell proliferation in insect development

PubMed Central

2012-01-01

Background Adenylate kinase 2 (AK2) is a phosphotransferase that catalyzes the reversible reaction 2ADP(GDP) ↔ ATP(GTP) + AMP and influences cellular energy homeostasis. However, the role of AK2 in regulating cell proliferation remains unclear because AK2 has been reported to be involved in either cell proliferation or cell apoptosis in different cell types of various organisms. Results This study reports AK2 promotion of cell proliferation using the lepidopteran insect Helicoverpa armigera and its epidermal cell line HaEpi as models. Western blot analysis indicates that AK2 constitutively expresses in various tissues during larval development. Immunocytochemistry analysis indicates that AK2 localizes in the mitochondria. The recombinant expressed AK2 in E. coli promotes cell growth and viability of HaEpi cell line by 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. AK2 knockdown in larvae by RNA interference causes larval growth defects, including body weight decrease and development delay. AK2 knockdown in larvae also decreases the number of circulating haemocytes. The mechanism for such effects might be the suppression of gene transcription involved in insect development caused by AK2 knockdown. Conclusion These results show that AK2 regulates cell growth, viability, and proliferation in insect growth and development. PMID:23020757

Juvenile Hormone Prevents 20-Hydroxyecdysone-induced Metamorphosis by Regulating the Phosphorylation of a Newly Identified Broad Protein*

PubMed Central

Cai, Mei-Juan; Liu, Wen; Pei, Xu-Yang; Li, Xiang-Ru; He, Hong-Juan; Wang, Jin-Xing; Zhao, Xiao-Fan

2014-01-01

The steroid hormone 20-hydroxyecdysone (20E) initiates insect molting and metamorphosis. By contrast, juvenile hormone (JH) prevents metamorphosis. However, the mechanism by which JH inhibits metamorphosis remains unclear. In this study, we propose that JH induces the phosphorylation of Broad isoform Z7 (BrZ7), a newly identified protein, to inhibit 20E-mediated metamorphosis in the lepidopteran insect Helicoverpa armigera. The knockdown of BrZ7 in larvae inhibited metamorphosis by repressing the expression of the 20E response gene. BrZ7 was weakly expressed and phosphorylated during larval growth but highly expressed and non-phosphorylated during metamorphosis. JH regulated the rapid phosphorylation of BrZ7 via a G-protein-coupled receptor-, phospholipase C-, and protein kinase C-triggered pathway. The phosphorylated BrZ7 bound to the 5′-regulatory region of calponin to regulate its expression in the JH pathway. Exogenous JH induced BrZ7 phosphorylation to prevent metamorphosis by suppressing 20E-related gene transcription. JH promoted non-phosphorylated calponin interacting with ultraspiracle protein to activate the JH pathway and antagonize the 20E pathway. This study reveals one of the possible mechanisms by which JH counteracts 20E-regulated metamorphosis by inducing the phosphorylation of BrZ7. PMID:25096576

Feeding behaviour of generalist pests on Brassica juncea: implication for manipulation of glucosinolate biosynthesis pathway for enhanced resistance.

PubMed

Kumar, Pawan; Augustine, Rehna; Singh, Amarjeet Kumar; Bisht, Naveen C

2017-10-01

Differential accumulation of plant defence metabolites has been suggested to have important ecological consequence in the context of plant-insect interactions. Feeding of generalist pests on Brassica juncea showed a distinct pattern with selective exclusion of leaf margins which are high in glucosinolates. Molecular basis of this differential accumulation of glucosinolates could be explained based on differential expression profile of BjuMYB28 homologues, the major biosynthetic regulators of aliphatic glucosinolates, as evident from quantitative real-time PCR and promoter:GUS fusion studies in allotetraploid B. juncea. Constitutive overexpression of selected BjuMYB28 homologues enhanced accumulation of aliphatic glucosinolates in B. juncea. Performance of two generalist pests, Helicoverpa armigera and Spodoptera litura larvae, on transgenic B. juncea plants were poor compared to wild-type plants in a no-choice experiment. Correlation coefficient analysis suggested that weight gain of H. armigera larvae was negatively correlated with gluconapin (GNA) and glucobrassicanapin (GBN), whereas that of S. litura larvae was negatively correlated with GNA, GBN and sinigrin (SIN). Our study explains the significance and possible molecular basis of differential distribution of glucosinolates in B. juncea leaves and shows the potential of overexpressing BjuMYB28 for enhanced resistance of Brassica crops against the tested generalist pests. © 2017 John Wiley & Sons Ltd.

Transgenic plants expressing the AaIT/GNA fusion protein show increased resistance and toxicity to both chewing and sucking pests.

PubMed

Liu, Shu-Min; Li, Jie; Zhu, Jin-Qi; Wang, Xiao-Wei; Wang, Cheng-Shu; Liu, Shu-Sheng; Chen, Xue-Xin; Li, Sheng

2016-04-01

The adoption of pest-resistant transgenic plants to reduce yield losses and decrease pesticide use has been successful. To achieve the goal of controlling both chewing and sucking pests in a given transgenic plant, we generated transgenic tobacco, Arabidopsis, and rice plants expressing the fusion protein, AaIT/GNA, in which an insecticidal scorpion venom neurotoxin (Androctonus australis toxin, AaIT) is fused to snowdrop lectin (Galanthus nivalis agglutinin, GNA). Compared with transgenic tobacco and Arabidopsis plants expressing AaIT or GNA, transgenic plants expressing AaIT/GNA exhibited increased resistance and toxicity to one chewing pest, the cotton bollworm, Helicoverpa armigera. Transgenic tobacco and rice plants expressing AaIT/GNA showed increased resistance and toxicity to two sucking pests, the whitefly, Bemisia tabaci, and the rice brown planthopper, Nilaparvata lugens, respectively. Moreover, in the field, transgenic rice plants expressing AaIT/GNA exhibited a significant improvement in grain yield when infested with N. lugens. This study shows that expressing the AaIT/GNA fusion protein in transgenic plants can be a useful approach for controlling pests, particularly sucking pests which are not susceptible to the toxin in Bt crops. © 2015 Institute of Zoology, Chinese Academy of Sciences.

Summer diapause induced by high temperatures in the oriental tobacco budworm: ecological adaptation to hot summers.

PubMed

Liu, Zhudong; Xin, Yucui; Zhang, Yanan; Fan, Jianting; Sun, Jianghua

2016-06-07

Summer diapause in Helicoverpa assulta (Hübner), which prolongs the pupal stage, particularly in males, is induced by high temperatures. In the laboratory, 3(rd)-, 4(th)-, 6(th)-instar and prepupal larvae were exposed to high temperatures - 33 and 35 °C with a photoperiod of LD16:8 - until pupation to induce summer diapause. The results showed that the incidence of summer diapause was influenced by temperature, stage exposed, and sex. The higher the temperature, the more often summer diapause was attained. Sixth-instar and prepupal larvae were the sensitive stages for summer diapause induction. H. assulta summer-diapausing pupae needed diapause development to resume development when temperatures became favorable. Furthermore, both body mass and energy storage capacity (lipid and glycogen) were significantly affected by diapause rather than sex, and were significantly higher in summer-diapausing pupae than in non-diapausing pupae. In addition, the body mass loss and respiration rate showed that the rate of metabolism in the summer-diapausing pupae was consistently lower than in non-diapausing pupae, which were significantly affected by diapause and pupal age. We conclude that summer diapause in H. assulta is a true diapause, and H. assulta has evolved mechanisms to accumulate energy storage and to lower its metabolism to adapt to hot summers.

Beauveria medogensis sp. nov., a new fungus of the entomopathogenic genus from China.

PubMed

Imoulan, Abdessamad; Wu, Hai-Jun; Lu, Wei-Lai; Li, Yi; Li, Bin-Bin; Yang, Rei-Heng; Wang, Wen-Jing; Wang, Xiao-Liang; Kirk, Paul M; Yao, Yi-Jian

2016-09-01

Beauveria is among the most ubiquitous genera of entomopathogenic fungi throughout the world. A previously unknown species of the genus was recently discovered from a soil sample collected from Tibetan Plateau, China and is here described as new to science, B. medogensis sp. nov. The new species is distinguished from its closest relatives based on both morphological characterization and molecular phylogenetic analyses. Beauveria medogensis is characterized by globose to subglobose conidia, morphologically similar to some other species of in the genus, but was conclusively separated from those species in the phylogenetic analyses including sequences of four nuclear genes (RPB1, RPB2, TEF1 and Bloc). The new species was clustered in the analyses in a single terminal lineage which was grouped with B. australis sequences together as a sister clade to the B. brongniartii terminal clade. Although molecularly closely related, the new species is distinct morphologically from its closest sisters, B. australis and B. brongniartii, in producing globose to subglobose conidia rather than subglobose, broadly ellipsoid to ellipsoid conidia or ellipsoidal to cylindrical conidia. As isolated from a soil sample, the entomopathogenicity of the new species has been confirmed using Helicoverpa armigera and Tenebrio molitor larvae. Copyright © 2016 Elsevier Inc. All rights reserved.

MYC2 Differentially Modulates Diverse Jasmonate-Dependent Functions in Arabidopsis[W

PubMed Central

Dombrecht, Bruno; Xue, Gang Ping; Sprague, Susan J.; Kirkegaard, John A.; Ross, John J.; Reid, James B.; Fitt, Gary P.; Sewelam, Nasser; Schenk, Peer M.; Manners, John M.; Kazan, Kemal

2007-01-01

The Arabidopsis thaliana basic helix-loop-helix Leu zipper transcription factor (TF) MYC2/JIN1 differentially regulates jasmonate (JA)-responsive pathogen defense (e.g., PDF1.2) and wound response (e.g., VSP) genes. In this study, genome-wide transcriptional profiling of wild type and mutant myc2/jin1 plants followed by functional analyses has revealed new roles for MYC2 in the modulation of diverse JA functions. We found that MYC2 negatively regulates Trp and Trp-derived secondary metabolism such as indole glucosinolate biosynthesis during JA signaling. Furthermore, MYC2 positively regulates JA-mediated resistance to insect pests, such as Helicoverpa armigera, and tolerance to oxidative stress, possibly via enhanced ascorbate redox cycling and flavonoid biosynthesis. Analyses of MYC2 cis binding elements and expression of MYC2-regulated genes in T-DNA insertion lines of a subset of MYC2–regulated TFs suggested that MYC2 might modulate JA responses via differential regulation of an intermediate spectrum of TFs with activating or repressing roles in JA signaling. MYC2 also negatively regulates its own expression, and this may be one of the mechanisms used in fine-tuning JA signaling. Overall, these results provide new insights into the function of MYC2 and the transcriptional coordination of the JA signaling pathway. PMID:17616737

Differential Adsorption of Occluded and Nonoccluded Insect-Pathogenic Viruses to Soil-Forming Minerals

PubMed Central

Christian, Peter D.; Richards, Andrew R.; Williams, Trevor

2006-01-01

Soil represents the principal environmental reservoir of many insect-pathogenic viruses. We compared the adsorption and infectivity of one occluded and two nonoccluded viruses, Helicoverpa armigera single nucleopolyhedrovirus (HaSNPV) (Baculoviridae), Cricket paralysis virus (CrPV) (Dicistroviridae), and Invertebrate iridescent virus 6 (IIV-6) (Iridoviridae), respectively, in mixtures with a selection of soil-forming minerals. The relative infective titers of HaSNPV and CrPV were unchanged or slightly reduced in the presence of different minerals compared to their titers in the absence of the mineral. In contrast, the infective titer of IIV-6 varied according to the mineral being tested. In adsorption studies, over 98% of HaSNPV occlusion bodies were adsorbed by all the minerals, and a particularly high affinity was observed with ferric oxide, attapulgite, and kaolinite. In contrast, the adsorption of CrPV and IIV-6 differed markedly with mineral type, with low affinity to bentonites and high affinity to ferric oxide and kaolinite. We conclude that interactions between soil-forming minerals and insect viruses appear to be most important in nucleopolyhedroviruses, followed by invertebrate iridescent viruses, and least important in CrPV, which may reflect the ecology of these pathogens. Moreover, soils with a high content of iron oxides or kaolinite would likely represent highly effective reservoirs for insect-pathogenic viruses. PMID:16820456

Molecular and Insecticidal Characterization of a Novel Cry-Related Protein from Bacillus Thuringiensis Toxic against Myzus persicae

PubMed Central

Palma, Leopoldo; Muñoz, Delia; Berry, Colin; Murillo, Jesús; Ruiz de Escudero, Iñigo; Caballero, Primitivo

2014-01-01

This study describes the insecticidal activity of a novel Bacillus thuringiensis Cry-related protein with a deduced 799 amino acid sequence (~89 kDa) and ~19% pairwise identity to the 95-kDa-aphidicidal protein (sequence number 204) from patent US 8318900 and ~40% pairwise identity to the cancer cell killing Cry proteins (parasporins Cry41Ab1 and Cry41Aa1), respectively. This novel Cry-related protein contained the five conserved amino acid blocks and the three conserved domains commonly found in 3-domain Cry proteins. The protein exhibited toxic activity against the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae) with the lowest mean lethal concentration (LC50 = 32.7 μg/mL) reported to date for a given Cry protein and this insect species, whereas it had no lethal toxicity against the Lepidoptera of the family Noctuidae Helicoverpa armigera (Hübner), Mamestra brassicae (L.), Spodoptera exigua (Hübner), S. frugiperda (J.E. Smith) and S. littoralis (Boisduval), at concentrations as high as ~3.5 μg/cm2. This novel Cry-related protein may become a promising environmentally friendly tool for the biological control of M. persicae and possibly also for other sap sucking insect pests. PMID:25384108

Developing Bisexual Attract-and-Kill for Polyphagous Insects: Ecological Rationale versus Pragmatics.

PubMed

Gregg, Peter C; Del Socorro, Alice P; Hawes, Anthony J; Binns, Matthew R

2016-07-01

We discuss the principles of bisexual attract-and-kill, in which females as well as males are targeted with an attractant, such as a blend of plant volatiles, combined with a toxicant. While the advantages of this strategy have been apparent for over a century, there are few products available to farmers for inclusion in integrated pest management schemes. We describe the development, registration, and commercialization of one such product, Magnet(®), which was targeted against Helicoverpa armigera and H. punctigera in Australian cotton. We advocate an empirical rather than theoretical approach to selecting and blending plant volatiles for such products, and emphasise the importance of field studies on ecologically realistic scales of time and space. The properties required of insecticide partners also are discussed. We describe the studies that were necessary to provide data for registration of the Magnet(®) product. These included evidence of efficacy, including local and area-wide impacts on the target pest, non-target impacts, and safety for consumers and applicators. In the decade required for commercial development, the target market for Magnet(®) has been greatly reduced by the widespread adoption of transgenic insect-resistant cotton in Australia. We discuss potential applications in resistance management for transgenic cotton, and for other pests in cotton and other crops.

Mesohabitat use of threatened hemlock forests by breeding birds of the Delaware River basin in northeastern United States

USGS Publications Warehouse

Ross, R.M.; Redell, L.A.; Bennett, R.M.; Young, J.A.

2004-01-01

Avian biodiversity may be at risk in eastern parks and forests due to continued expansion of the hemlock woolly adelgid (Adelges tsugae), an exotic homopteran insect native to East Asia. To assess avian biodiversity, mesohabitat relations, and the risk of species loss with declining hemlock forests in Appalachian park lands, 80 randomly distributed fixed-radius plots were established in which territories of breeding birds were estimated on four forest-terrain types (hemlock and hardwood benches and ravines) in the Delaware Water Gap National Recreation Area. Both species richness and number of territories were higher in hardwood than hemlock forest types and in bench than ravine terrain types. Four insectivorous species, Acadian flycatcher (Empidonax virescens), blue-headed vireo (Vireo solitarius), black-throated green warbler (Dendroica virens), and Blackburnian warbler (Dendroica fusca), showed high affinity for hemlock forest type and exhibited significantly greater numbers of territories in hemlock than hardwood sites. These species are hemlock-associated species at risk from continued hemlock decline in the Delaware River valley and similar forests of the mid-Atlantic east slope. Two of these species, the blue-headed vireo and Blackburnian warbler, appeared to specialize on ravine mesohabitats of hemlock stands, the vireo a low-to-mid canopy species, the warbler a mid-to-upper canopy forager. Unchecked expansion of the exotic adelgid and subsequent hemlock decline could negatively impact 3,600 pairs from the park and several million pairs from northeastern United States hemlock forests due to elimination of preferred habitat.

Visitation by wild and managed bees (Hymenoptera: Apoidea) to eastern U.S. native plants for use in conservation programs.

PubMed

Tuell, Julianna K; Fiedler, Anna K; Landis, Douglas; Isaacs, Rufus

2008-06-01

Addition of floral resources to agricultural field margins has been shown to increase abundance of beneficial insects in crop fields, but most plants recommended for this use are non-native annuals. Native perennial plants with different bloom periods can provide floral resources for bees throughout the growing season for use in pollinator conservation projects. To identify the most suitable plants for this use, we examined the relative attractiveness to wild and managed bees of 43 eastern U.S. native perennial plants, grown in a common garden setting. Floral characteristics were evaluated for their ability to predict bee abundance and taxa richness. Of the wild bees collected, the most common species (62%) was Bombus impatiens Cresson. Five other wild bee species were present between 3 and 6% of the total: Lasioglossum admirandum (Sandhouse), Hylaeus affinis (Smith), Agapostemon virescens (F.), Halictus ligatus Say, and Ceratina calcarata/dupla Robertson/Say. The remaining wild bee species were present at <2% of the total. Abundance of honey bees (Apis mellifera L.) was nearly identical to that of B. impatiens. All plant species were visited at least once by wild bees; 9 were highly attractive, and 20 were moderately attractive. Honey bees visited 24 of the 43 plant species at least once. Floral area was the only measured factor accounting for variation in abundance and richness of wild bees but did not explain variation in honey bee abundance. Results of this study can be used to guide selection of flowering plants to provide season-long forage for conservation of wild bees.

Does Passive Sampling Accurately Reflect the Bee (Apoidea: Anthophila) Communities Pollinating Apple and Sour Cherry Orchards?

PubMed

Gibbs, Jason; Joshi, Neelendra K; Wilson, Julianna K; Rothwell, Nikki L; Powers, Karen; Haas, Mike; Gut, Larry; Biddinger, David J; Isaacs, Rufus

2017-06-01

During bloom of spring orchard crops, bees are the primary providers of pollination service. Monitoring these insects for research projects is often done by timed observations or by direct aerial netting, but there has been increasing interest in blue vane traps as an efficient passive approach to collecting bees. Over multiple spring seasons in Michigan and Pennsylvania, orchards were monitored for wild bees using timed netting from crop flowers and blue vane traps. This revealed a distinctly different community of wild bees captured using the two methods, suggesting that blue vane traps can complement but cannot replace direct aerial netting. The bee community in blue vane traps was generally composed of nonpollinating species, which can be of interest for broader biodiversity studies. In particular, blue vane traps caught Eucera atriventris (Smith), Eucera hamata (Bradley), Bombus fervidus (F.), and Agapostemon virescens (F.) that were never collected from the orchard crop flowers during the study period. Captures of bee species in nets was generally stable across the 3 yr, whereas we observed significant declines in the abundance of Lasioglossum pilosum (Smith) and Eucera spp. trapped using blue vane traps during the project, suggesting local overtrapping of reproductive individuals. We conclude that blue vane traps are a useful tool for expanding insights into bee communities within orchard crop systems, but they should be used with great caution to avoid local extirpation of these important insects. © 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.

The role of ecologic diversification in sibling speciation of Empidonax flycatchers (Tyrannidae): multigene evidence from mtDNA.

PubMed

Johnson, N K; Cicero, C

2002-10-01

Avian genera characterized by sibling species with distinctive habitat preferences present an evolutionary enigma in view of the more commonplace occurrence of syntopic congeners that differ strikingly in colour and pattern. No existing theory has explained the evolutionary background that led to these differences. Here we propose that great phenotypic similarity among some groups of sibling species limits their coexistence and that clues to their radiation can be seen in patterns of geographical occurrence. To illustrate our thesis we focused on the New World flycatcher genus Empidonax, a group of 15 species notorious for their great phenotypic similarity. Using 3069 base pairs of mitochondrial DNA from four genes, we produced a complete molecular phylogeny that identified four clades, three of which represent close relatives. The fourth clade includes only E. virescens, which apparently has no close living relatives. The majority of species, including many distant relatives, are completely (58.1%) or essentially (6.7%) allopatric in breeding distribution and exhibit striking ecological segregation into distinctive climate-vegetation zones. Even where ranges overlap, occupancy of the same habitat by different species is rare. Phylogenetic and distributional patterns in Empidonax suggest a peripatric model of stepwise colonization and then range expansion of small groups of pioneers during glacial periods into initially enlarging, distinctive habitats destined to be widespread during interglacials. Vicariance is not indicated in the absence of barriers of appropriate age and geographical position. Rapoport's rule that northern species have larger ranges than southern species is strongly supported.

Survey of ciguatera at Enewetak and Bikini, Marshall Islands, with notes on the systematics and food habits of ciguatoxic fishes

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

Randall, J.E.

1980-04-01

A total of 551 specimens of 48 species of potentially ciguatoxic fishes from Enewetak and 256 specimens of 23 species from Bikini, Marshall Islands, were tested for ciguatoxin by feeding liver or liver and viscera from these fishes to mongooses at 10% body weight (except for sharks, when only muscle tissue was used). The fishes are representatives of the following families: Orectolobidae, Carcharhinidae, Dasyatidae, Muraenidae, Holocentridae, Sphyraenidae, Mugilidae, Serranidae, Lutjanidae, Lethrinidae, Carangidae, Scombridae, Labridae, Scaridae, Acanthuridae, and Balistidae. The species selected were all ones for which toxicity can be expected, including the worst offenders from reports of ciguatera throughout Oceania;more » only moderate to large-sized adults were tested. In all, 37.3% of the fishes from Enewetak and 19.7% from Bikini gave a positive reaction for ciguatoxin. Because liver and other viscera are more toxic than muscle, the percentage of positive reactions at the level which might cause illness in humans eating only the flesh of these fishes collectively would drop to 16.2 for Enewetak and 1.4 for Bikini. This level of toxicity is not regarded as high for Pacific islands, in general. Because ciguatoxin is acquired through feeding, the food habits of these fishes were investigated. Most of the highly toxic species, including seven of the eight causing severe illness or death in the test animals (Lycodontis javanicus, Cephalopholis argus, Epinephelus hoedtii, E. microdon, Plectropomus leopardus, Aprion virescens, and Lutjanus bohar) are primarily piscivorous.« less

From Metchnikoff to Monsanto and beyond: the path of microbial control.

PubMed

Lord, Jeffrey C

2005-05-01

In 125 years since Metchnikoff proposed the use of Metarhizium anisopliae to control the wheat cockchafer and brought about the first field trials, microbial control has progressed from the application of naturalists' observations to biotechnology and precision delivery. This review highlights major milestones in its evolution and presents a perspective on its current direction. Fungal pathogens, the most eye-catching agents, dominated the early period, but major mycological control efforts for chinch bugs and citrus pests in the US had questionable success, and interest waned. The discoveries of Bacillus popilliae and Bacillus thuringiensis began the era of practical and commercially viable microbial control. A program to control the Japanese beetle in the US led to the discovery of both B. popilliae and Steinernema glaseri, the first nematode used as a microbial control agent. Viral insect control became practical in the latter half of the 20th century, and the first registration was obtained with the Heliothis nuclear polyhedrosis virus in 1975. Now strategies are shifting for microbial control. While Bt transgenic crops are now planted on millions of hectares, the successes of more narrowly defined microbial control are mainly in small niches. Commercial enthusiasm for traditional microbial control agents has been unsteady in recent years. The prospects of microbial insecticide use on vast areas of major crops are now viewed more realistically. Regulatory constraints, activist resistance, benign and efficacious chemicals, and limited research funding all drive changes in focus. Emphasis is shifting to monitoring, conservation, integration with chemical pesticides, and selection of favorable venues such as organic agriculture and countries that have low costs, mild regulatory climates, modest chemical inputs, and small scale farming.

Biochemical characterisation of α-amylase inhibitors from Achyranthes aspera and their interactions with digestive amylases of coleopteran and lepidopteran insects.

PubMed

Hivrale, Vandana K; Chougule, Nanasaheb P; Giri, Ashok P; Chhabda, Pavan J; Kachole, Manvendra S

2011-08-15

Starchy seeds are an important food and a source of dietary ingredients in many countries. However, they suffer from extensive predation by bruchids (weevils) and other pests. α-Amylase inhibitors are attractive candidates for the control of seed weevils, as these insects are highly dependent on starch as an energy source. A proteinaceous α-amylase inhibitor from the seeds of Achyranthes aspera was identified, purified and characterised. In electrophoretic analysis, two prominent amylase inhibitor activity bands (AI1 and AI2) were detected. The inhibitor was purified 9.99-fold with 1206.95 total amylase inhibitor units mg⁻¹ protein. The molecular weight of the purified inhibitor was around 6 kDa. The isolated α-amylase inhibitor was found to be resistant to heat and proteolysis. Feeding analysis of Callosobruchus maculatus larvae on a diet containing seed powder of A. aspera revealed that survival of the larvae was severely affected, with the highest mortality rate occurring on the fifth day of feeding. The isolated inhibitor inhibited the majority of amylase isoforms of C. maculatus, Tribolium confusum and Helicoverpa armigera in electrophoretic analysis and solution assays. The information obtained in the present investigation could be useful for a genetic engineering approach that would make seeds resistant to storage pest infestations. Copyright © 2011 Society of Chemical Industry.

A challenge for the seed mixture refuge strategy in Bt maize: impact of cross-pollination on an ear-feeding pest, corn earworm.

PubMed

Yang, Fei; Kerns, David L; Head, Graham P; Leonard, B Rogers; Levy, Ronnie; Niu, Ying; Huang, Fangneng

2014-01-01

To counter the threat of insect resistance, Bacillus thuringiensis (Bt) maize growers in the U.S. are required to plant structured non-Bt maize refuges. Concerns with refuge compliance led to the introduction of seed mixtures, also called RIB (refuge-in-the-bag), as an alternative approach for implementing refuge for Bt maize products in the U.S. Maize Belt. A major concern in RIB is cross-pollination of maize hybrids that can cause Bt proteins to be present in refuge maize kernels and negatively affect refuge insects. Here we show that a mixed planting of 5% nonBt and 95% Bt maize containing the SmartStax traits expressing Cry1A.105, Cry2Ab2 and Cry1F did not provide an effective refuge for an important above-ground ear-feeding pest, the corn earworm, Helicoverpa zea (Boddie). Cross-pollination in RIB caused a majority (>90%) of refuge kernels to express ≥ one Bt protein. The contamination of Bt proteins in the refuge ears reduced neonate-to-adult survivorship of H. zea to only 4.6%, a reduction of 88.1% relative to larvae feeding on ears of pure non-Bt maize plantings. In addition, the limited survivors on refuge ears had lower pupal mass and took longer to develop to adults.

Bioprospecting for secondary metabolites in the entomopathogenic bacterium Photorhabdus luminescens subsp. sonorensis.

PubMed

Orozco, Rousel A; Molnár, István; Bode, Helge; Stock, S Patricia

2016-11-01

Crude extracts of in vitro and in vivo cultures of two strains of Photorhabdus l. sonorensis (Enterobacteriaceae) were analyzed by TLC, HPLC-UV and LC-MS. Nine unique compounds with mass/charge ratios (m/z) ranging from 331.3 to 713.5 were found in MS analyses. Bioactivity of extracts was assessed on a selection of plant pathogens/pests and non-target species. Caborca strain extracts showed the highest activity against Helicoverpa zea (Lepidoptera: Noctuidae) neonates at all concentrations tested. Mortality ranged from 11% (at 10μg/ml) to 37% (at 40μg/ml). Strain CH35 extracts showed the highest nematicidal activity on Meloidogyne incognita (Tylenchida: Meloidogynidae) at 40μg/ml. Low to no nematicidal activity was observed against the non-target species Steinernema carpocapsae (Rhabditida: Steinernematidae) and Caenorhabditis elegans (Rhabditida: Rhabditidae). Caborca extracts exhibited a strong antibiotic effect on Pseudomonas syringae (Pseudomonadales: Pseudomonadacedae) at 40μg/ml, while both Caborca and CH35 extracts inhibited the growth of Bacillus subitillis (Bacillales: Bacillaceae) at 40μg/ml. All extracts strongly inhibited the growth of the fungus Fusarium oxysporum (Hypocreales: Nectriceae) but not that of Alternaria alternata (Pleosporales: Pleosporaceae). Contrastingly, a moderate to high inhibitory effect was denoted on the non-target biocontrol fungus Beauveria bassiana (Hypocreales: Clavivipitaceae). Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

Juvenile hormone prevents 20-hydroxyecdysone-induced metamorphosis by regulating the phosphorylation of a newly identified broad protein.

PubMed

Cai, Mei-Juan; Liu, Wen; Pei, Xu-Yang; Li, Xiang-Ru; He, Hong-Juan; Wang, Jin-Xing; Zhao, Xiao-Fan

2014-09-19

The steroid hormone 20-hydroxyecdysone (20E) initiates insect molting and metamorphosis. By contrast, juvenile hormone (JH) prevents metamorphosis. However, the mechanism by which JH inhibits metamorphosis remains unclear. In this study, we propose that JH induces the phosphorylation of Broad isoform Z7 (BrZ7), a newly identified protein, to inhibit 20E-mediated metamorphosis in the lepidopteran insect Helicoverpa armigera. The knockdown of BrZ7 in larvae inhibited metamorphosis by repressing the expression of the 20E response gene. BrZ7 was weakly expressed and phosphorylated during larval growth but highly expressed and non-phosphorylated during metamorphosis. JH regulated the rapid phosphorylation of BrZ7 via a G-protein-coupled receptor-, phospholipase C-, and protein kinase C-triggered pathway. The phosphorylated BrZ7 bound to the 5'-regulatory region of calponin to regulate its expression in the JH pathway. Exogenous JH induced BrZ7 phosphorylation to prevent metamorphosis by suppressing 20E-related gene transcription. JH promoted non-phosphorylated calponin interacting with ultraspiracle protein to activate the JH pathway and antagonize the 20E pathway. This study reveals one of the possible mechanisms by which JH counteracts 20E-regulated metamorphosis by inducing the phosphorylation of BrZ7. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Improvement of pest resistance in transgenic tobacco plants expressing dsRNA of an insect-associated gene EcR.

PubMed

Zhu, Jin-Qi; Liu, Shumin; Ma, Yao; Zhang, Jia-Qi; Qi, Hai-Sheng; Wei, Zhao-Jun; Yao, Qiong; Zhang, Wen-Qing; Li, Sheng

2012-01-01

The adoption of pest-resistant transgenic plants to reduce yield loss and pesticide utilization has been successful in the past three decades. Recently, transgenic plant expressing double-stranded RNA (dsRNA) targeting pest genes emerges as a promising strategy for improving pest resistance in crops. The steroid hormone, 20-hydroxyecdysone (20E), predominately controls insect molting via its nuclear receptor complex, EcR-USP. Here we report that pest resistance is improved in transgenic tobacco plants expressing dsRNA of EcR from the cotton bollworm, Helicoverpa armigera, a serious lepidopteran pest for a variety of crops. When H. armigera larvae were fed with the whole transgenic tobacco plants expressing EcR dsRNA, resistance to H. armigera was significantly improved in transgenic plants. Meanwhile, when H. armigera larvae were fed with leaves of transgenic tobacco plants expressing EcR dsRNA, its EcR mRNA level was dramatically decreased causing molting defects and larval lethality. In addition, the transgenic tobacco plants expressing H. armigera EcR dsRNA were also resistant to another lepidopteran pest, the beet armyworm, Spodoptera exigua, due to the high similarity in the nucleotide sequences of their EcR genes. This study provides additional evidence that transgenic plant expressing dsRNA targeting insect-associated genes is able to improve pest resistance.

Gossypolhemiquinone, a dimeric sesquiterpenoid identified in cotton (Gossypium).

PubMed

Stipanovic, Robert; Puckhaber, Lorraine; Frelichowski, James; Esquivel, Jesus; Westbrook, John; O'Neil, Mike; Bell, Alois; Dowd, Michael; Hake, Kater; Duke, Sara

2016-02-01

The report that the cotton leaf perforator, Bucculatrix thurberiella, is one of the few insect herbivores to attack Gossypium thurberi prompted an investigation of the terpenoids present in the leaves of this wild species of cotton. Members of Gossypium produce subepidermal pigment glands in their leaves that contain the dimeric sesquiterpenoid gossypol as well as other biosynthetically related terpenoids. In addition to gossypol, a previously unknown dimeric sesquiterpenoid, gossypolhemiquinone (GHQ), was identified in trace amounts in G. thurberi, a member of the D genome. Other members of the D genome of Gossypium were subsequently found to contain this compound, but GHQ was not detected in commercial cotton cultivars. When fed to Helicoverpa zea in an artificial diet, GHQ delayed days-to-pupation, reduced pupal weights, and survival to adulthood to a lesser or equal extent than gossypol in comparison to the control diet. However, GHQ had a synergistic effect on survival and days-to-pupation when combined with gossypol at the highest dosage tested (0.18%; 15.5:84.5 GHQ:gossypol). Because gossypol exhibits anti-cancer activity, GHQ was also evaluated for its anti-cancer activity against the National Cancer Institute's 60-Human Tumor Cell Line Screen. Significant inhibitory activity against most of these cell lines was not observed, but the results may offer some promise against leukemia cancer cell lines. Published by Elsevier Ltd.

Summer diapause induced by high temperatures in the oriental tobacco budworm: ecological adaptation to hot summers

PubMed Central

Liu, Zhudong; Xin, Yucui; Zhang, Yanan; Fan, Jianting; Sun, Jianghua

2016-01-01

Summer diapause in Helicoverpa assulta (Hübner), which prolongs the pupal stage, particularly in males, is induced by high temperatures. In the laboratory, 3rd-, 4th-, 6th-instar and prepupal larvae were exposed to high temperatures – 33 and 35 °C with a photoperiod of LD16:8 – until pupation to induce summer diapause. The results showed that the incidence of summer diapause was influenced by temperature, stage exposed, and sex. The higher the temperature, the more often summer diapause was attained. Sixth-instar and prepupal larvae were the sensitive stages for summer diapause induction. H. assulta summer-diapausing pupae needed diapause development to resume development when temperatures became favorable. Furthermore, both body mass and energy storage capacity (lipid and glycogen) were significantly affected by diapause rather than sex, and were significantly higher in summer-diapausing pupae than in non-diapausing pupae. In addition, the body mass loss and respiration rate showed that the rate of metabolism in the summer-diapausing pupae was consistently lower than in non-diapausing pupae, which were significantly affected by diapause and pupal age. We conclude that summer diapause in H. assulta is a true diapause, and H. assulta has evolved mechanisms to accumulate energy storage and to lower its metabolism to adapt to hot summers. PMID:27271223

Molecular basis of the remarkable species selectivity of an insecticidal sodium channel toxin from the African spider Augacephalus ezendami

NASA Astrophysics Data System (ADS)

Herzig, Volker; Ikonomopoulou, Maria; Smith, Jennifer J.; Dziemborowicz, Sławomir; Gilchrist, John; Kuhn-Nentwig, Lucia; Rezende, Fernanda Oliveira; Moreira, Luciano Andrade; Nicholson, Graham M.; Bosmans, Frank; King, Glenn F.

2016-07-01

The inexorable decline in the armament of registered chemical insecticides has stimulated research into environmentally-friendly alternatives. Insecticidal spider-venom peptides are promising candidates for bioinsecticide development but it is challenging to find peptides that are specific for targeted pests. In the present study, we isolated an insecticidal peptide (Ae1a) from venom of the African spider Augacephalus ezendami (family Theraphosidae). Injection of Ae1a into sheep blowflies (Lucilia cuprina) induced rapid but reversible paralysis. In striking contrast, Ae1a was lethal to closely related fruit flies (Drosophila melanogaster) but induced no adverse effects in the recalcitrant lepidopteran pest Helicoverpa armigera. Electrophysiological experiments revealed that Ae1a potently inhibits the voltage-gated sodium channel BgNaV1 from the German cockroach Blattella germanica by shifting the threshold for channel activation to more depolarized potentials. In contrast, Ae1a failed to significantly affect sodium currents in dorsal unpaired median neurons from the American cockroach Periplaneta americana. We show that Ae1a interacts with the domain II voltage sensor and that sensitivity to the toxin is conferred by natural sequence variations in the S1-S2 loop of domain II. The phyletic specificity of Ae1a provides crucial information for development of sodium channel insecticides that target key insect pests without harming beneficial species.

Dominant resistance to Bt cotton and minor cross-resistance to Bt toxin Cry2Ab in cotton bollworm from China

PubMed Central

Jin, Lin; Wei, Yiyun; Zhang, Lei; Yang, Yihua; Tabashnik, Bruce E; Wu, Yidong

2013-01-01

Evolution of resistance by insect pests threatens the long-term benefits of transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt). Previous work has detected increases in the frequency of resistance to Bt toxin Cry1Ac in populations of cotton bollworm, Helicoverpa armigera, from northern China where Bt cotton producing Cry1Ac has been grown extensively for more than a decade. Confirming that trend, we report evidence from 2011 showing that the percentage of individuals resistant to a diagnostic concentration of Cry1Ac was significantly higher in two populations from different provinces of northern China (1.4% and 2.3%) compared with previously tested susceptible field populations (0%). We isolated two resistant strains: one from each of the two field-selected populations. Relative to a susceptible strain, the two strains had 460- and 1200-fold resistance to Cry1Ac, respectively. Both strains had dominant resistance to a diagnostic concentration of Cry1Ac in diet and to Bt cotton leaves containing Cry1Ac. Both strains had low, but significant cross-resistance to Cry2Ab (4.2- and 5.9-fold), which is used widely as the second toxin in two-toxin Bt cotton. Compared with resistance in other strains of H. armigera, the resistance in the two strains characterized here may be especially difficult to suppress. PMID:24478804

Microbial control of phytophagous invertebrate pests in South Africa: Current status and future prospects.

PubMed

Hatting, Justin L; Moore, Sean D; Malan, Antoinette P

2018-02-07

Invertebrate pests pose a significant threat to food security on the African continent. In response, South Africa has become one of the largest importers of chemical pesticides in sub-Saharan Africa, with several hundred active ingredients registered. To address the over-reliance on such chemicals, the South African Department of Agriculture, Forestry and Fisheries (DAFF) has eliminated or restricted several pesticides since the late 1970s. The recent launch of the South African National Bio-Economy Strategy and establishment of the South African Bioproducts Organisation (SABO), together with new guidelines for registration of biopesticides in 2015, also support this endeavour. Concurrently, entomopathogen-related research and bioproduct development has increased over the past decade. Currently, 31 products (seven manufactured locally) are registered under the Fertilizers, Farm Feeds, Agricultural Remedies and Stock Remedies Act 36 of 1947. Commercially important microbes include Beauveria bassiana (Cordycipitaceae), Metarhizium anisopliae (Clavicipitaceae), Cydia pomonella granulovirus, Cryptophlebia leucotreta granulovirus, Helicoverpa armigera nucleopolyhedrovirus (Baculoviridae) and Bacillus thuringiensis subsp. kurstaki and B. thuringiensis subsp. aizawai (Bacillaceae). Both parasitic and entomopathogenic nematodes (EPNs) show potential for development as bioinsecticides with one commercial EPN product, based on Heterorhabditis bacteriophora (Heterorhabditidae), registered under the Act. Rapid scientific progression, supported by a favourable legislative environment, should facilitate further advances in microbial control of phytophagous invertebrate pests in South Africa. Copyright © 2018 Elsevier Inc. All rights reserved.

A Single Point Mutation Resulting in Cadherin Mislocalization Underpins Resistance against Bacillus thuringiensis Toxin in Cotton Bollworm*

PubMed Central

Xiao, Yutao; Dai, Qing; Hu, Ruqin; Pacheco, Sabino; Yang, Yongbo; Liang, Gemei; Soberón, Mario

2017-01-01

Transgenic plants that produce Bacillus thuringiensis (Bt) crystalline (Cry) toxins are cultivated worldwide to control insect pests. Resistance to B. thuringiensis toxins threatens this technology, and although different resistance mechanisms have been identified, some have not been completely elucidated. To gain new insights into these mechanisms, we performed multiple back-crossing from a 3000-fold Cry1Ac-resistant BtR strain from cotton bollworm (Helicoverpa armigera), isolating a 516-fold Cry1Ac-resistant strain (96CAD). Cry1Ac resistance in 96CAD was tightly linked to a mutant cadherin allele (mHaCad) that contained 35 amino acid substitutions compared with HaCad from a susceptible strain (96S). We observed significantly reduced levels of the mHaCad protein on the surface of the midgut epithelium in 96CAD as compared with 96S. Expression of both cadherin alleles from 96CAD and 96S in insect cells and immunofluorescence localization in insect midgut tissue sections showed that the HaCAD protein from 96S localizes on the cell membrane, whereas the mutant 96CAD-mHaCad was retained in the endoplasmic reticulum (ER). Mapping of the mutations identified a D172G substitution mainly responsible for cadherin mislocalization. Our finding of a mutation affecting membrane receptor trafficking represents an unusual and previously unrecognized B. thuringiensis resistance mechanism. PMID:28082675

Conserved chemosensory proteins in the proboscis and eyes of Lepidoptera.

PubMed

Zhu, Jiao; Iovinella, Immacolata; Dani, Francesca Romana; Liu, Yu-Ling; Huang, Ling-Qiao; Liu, Yang; Wang, Chen-Zhu; Pelosi, Paolo; Wang, Guirong

2016-01-01

Odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) are endowed with several different functions besides being carriers for pheromones and odorants. Based on a previous report of a CSP acting as surfactant in the proboscis of the moth Helicoverpa armigera , we revealed the presence of orthologue proteins in two other moths Plutella xylostella and Chilo suppressalis , as well as two butterflies Papilio machaon and Pieris rapae , using immunodetection and proteomic analysis. The unusual conservation of these proteins across large phylogenetic distances indicated a common specific function for these CSPs. This fact prompted us to search for other functions of these proteins and discovered that CSPs are abundantly expressed in the eyes of H. armigera and possibly involved as carriers for carotenoids and visual pigments. This hypothesis is supported by ligand-binding experiments and docking simulations with retinol and β-carotene. This last orange pigment, occurring in many fruits and vegetables, is an antioxidant and the precursor of visual pigments. We propose that structurally related CSPs solubilise nutritionally important carotenoids in the proboscis, while they act as carriers of both β-carotene and its derived products 3-hydroxyretinol and 3-hydroxyretinal in the eye. The use of soluble olfactory proteins, such as CSPs, as carriers for visual pigments in insects, here reported for the first time, parallels the function of retinol-binding protein in vertebrates, a lipocalin structurally related to vertebrate odorant-binding proteins.

Activation of Bt Protoxin Cry1Ac in Resistant and Susceptible Cotton Bollworm.

PubMed

Wei, Jizhen; Liang, Gemei; Wang, Bingjie; Zhong, Feng; Chen, Lin; Khaing, Myint Myint; Zhang, Jie; Guo, Yuyuan; Wu, Kongming; Tabashnik, Bruce E

2016-01-01

Crystalline (Cry) proteins from Bacillus thuringiensis (Bt) are used extensively for insect control in sprays and transgenic plants, but their efficacy is reduced by evolution of resistance in pests. Here we evaluated reduced activation of Cry1Ac protoxin as a potential mechanism of resistance in the invasive pest Helicoverpa armigera. Based on the concentration killing 50% of larvae (LC50) for a laboratory-selected resistant strain (LF120) divided by the LC50 for its susceptible parent strain (LF), the resistance ratio was 1600 for Cry1Ac protoxin and 1200 for trypsin-activated Cry1Ac toxin. The high level of resistance to activated toxin as well as to protoxin indicates reduced activation of protoxin is not a major mechanism of resistance to Cry1Ac in LF120. For both insect strains, treatment with either the trypsin inhibitor N-a-tosyl-L-lysine chloromethyl ketone (TLCK) or the chymotrypsin inhibitor N-a-tosyl-L-phenylalanine chloromethyl ketone (TPCK) did not significantly affect the LC50 of Cry1Ac protoxin. Enzyme activity was higher for LF than LF120 for trypsin-like proteases, but did not differ between strains for chymotrypsin-like proteases. The results here are consistent with previous reports indicating that reduced activation of protoxin is generally not a major mechanism of resistance to Bt proteins.

Activation of Bt Protoxin Cry1Ac in Resistant and Susceptible Cotton Bollworm

PubMed Central

Liang, Gemei; Wang, Bingjie; Zhong, Feng; Chen, Lin; Khaing, Myint Myint; Zhang, Jie; Guo, Yuyuan; Wu, Kongming; Tabashnik, Bruce E.

2016-01-01

Crystalline (Cry) proteins from Bacillus thuringiensis (Bt) are used extensively for insect control in sprays and transgenic plants, but their efficacy is reduced by evolution of resistance in pests. Here we evaluated reduced activation of Cry1Ac protoxin as a potential mechanism of resistance in the invasive pest Helicoverpa armigera. Based on the concentration killing 50% of larvae (LC50) for a laboratory-selected resistant strain (LF120) divided by the LC50 for its susceptible parent strain (LF), the resistance ratio was 1600 for Cry1Ac protoxin and 1200 for trypsin-activated Cry1Ac toxin. The high level of resistance to activated toxin as well as to protoxin indicates reduced activation of protoxin is not a major mechanism of resistance to Cry1Ac in LF120. For both insect strains, treatment with either the trypsin inhibitor N-a-tosyl-L-lysine chloromethyl ketone (TLCK) or the chymotrypsin inhibitor N-a-tosyl-L-phenylalanine chloromethyl ketone (TPCK) did not significantly affect the LC50 of Cry1Ac protoxin. Enzyme activity was higher for LF than LF120 for trypsin-like proteases, but did not differ between strains for chymotrypsin-like proteases. The results here are consistent with previous reports indicating that reduced activation of protoxin is generally not a major mechanism of resistance to Bt proteins. PMID:27257885

Baited traps may be an alternative to conventional pesticides in integrated crop management of chicory (Compositae) in South Africa.

PubMed

Midgley, J M; Hill, M P; Villet, M H

2008-02-01

Chicory, Chicorium intybus L. (Compositae), is a major field crop in the Eastern Cape Province of South Africa. Several pests feed on the leaves of the plant, resulting in reduced yield. The most important of these are the noctuid moths Helicoverpa armigera (Hübner), Chrysodeixis acuta (Walker), and Trichoplusia orichalcea (F.). The use of attract-and-kill traps offers an alternative to broad-based insecticides in the control of these species. Three fields were treated with normal insecticides and three fields with yellow-baited traps. Eight additional traps were placed in each field, with half of the traps containing the insecticide 2,2-dichlorovinyl dimethyl phosphate (dichlorvos) and half without dichlorvos; and half yellow and half green. Total moth numbers and nonphytophage diversity were measured from these eight traps. Although no differences in H. armigera or T. orichalcea catches were observed between insecticide- and trap-treated fields, numbers of C. acuta and the total number of moths were significantly higher in insecticide-treated fields. Yellow traps containing dichlorvos contained more moths than yellow traps without dichlorvos, or green traps with dichlorvos, or green traps without dichlorvos; but they also contained more nonphytophagous insects. Yellow traps also enhanced the catches of thrips on card traps associated with them. These results offer an opportunity for the South African chicory industry to reduce pesticide applications and thus mitigate environmental impacts.

Species-specific variation in nesting and postfledging resource selection for two forest breeding migrant songbirds.

PubMed

Jenkins, Julianna M A; Thompson, Frank R; Faaborg, John

2017-01-01

Habitat selection is a fundamental component of community ecology, population ecology, and evolutionary biology and can be especially important to species with complex annual habitat requirements, such as migratory birds. Resource preferences on the breeding grounds may change during the postfledging period for migrant songbirds, however, the degree to which selection changes, timing of change, and whether all or only a few species alter their resource use is unclear. We compared resource selection for nest sites and resource selection by postfledging juvenile ovenbirds (Seiurus aurocapilla) and Acadian flycatchers (Empidonax virescens) followed with radio telemetry in Missouri mature forest fragments from 2012-2015. We used Bayesian discrete choice modeling to evaluate support for local vegetation characteristics on the probability of selection for nest sites and locations utilized by different ages of postfledging juveniles. Patterns of resource selection variation were species-specific. Resource selection models indicated that Acadian flycatcher habitat selection criteria were similar for nesting and dependent postfledging juveniles and selection criteria diverged when juveniles became independent from adults. After independence, flycatcher resource selection was more associated with understory foliage density. Ovenbirds differed in selection criteria between the nesting and postfledging periods. Fledgling ovenbirds selected areas with higher densities of understory structure compared to nest sites, and the effect of foliage density on selection increased as juveniles aged and gained independence. The differences observed between two sympatric forest nesting species, in both the timing and degree of change in resource selection criteria over the course of the breeding season, illustrates the importance of considering species-specific traits and postfledging requirements when developing conservation efforts, especially when foraging guilds or prey bases differ. We recommend that postfledging habitat selection be considered in future conservation efforts dealing with Neotropical migrants and other forest breeding songbirds.

A removal model for estimating detection probabilities from point-count surveys

USGS Publications Warehouse

Farnsworth, G.L.; Pollock, K.H.; Nichols, J.D.; Simons, T.R.; Hines, J.E.; Sauer, J.R.

2002-01-01

Use of point-count surveys is a popular method for collecting data on abundance and distribution of birds. However, analyses of such data often ignore potential differences in detection probability. We adapted a removal model to directly estimate detection probability during point-count surveys. The model assumes that singing frequency is a major factor influencing probability of detection when birds are surveyed using point counts. This may be appropriate for surveys in which most detections are by sound. The model requires counts to be divided into several time intervals. Point counts are often conducted for 10 min, where the number of birds recorded is divided into those first observed in the first 3 min, the subsequent 2 min, and the last 5 min. We developed a maximum-likelihood estimator for the detectability of birds recorded during counts divided into those intervals. This technique can easily be adapted to point counts divided into intervals of any length. We applied this method to unlimited-radius counts conducted in Great Smoky Mountains National Park. We used model selection criteria to identify whether detection probabilities varied among species, throughout the morning, throughout the season, and among different observers. We found differences in detection probability among species. Species that sing frequently such as Winter Wren (Troglodytes troglodytes) and Acadian Flycatcher (Empidonax virescens) had high detection probabilities (∼90%) and species that call infrequently such as Pileated Woodpecker (Dryocopus pileatus) had low detection probability (36%). We also found detection probabilities varied with the time of day for some species (e.g. thrushes) and between observers for other species. We used the same approach to estimate detection probability and density for a subset of the observations with limited-radius point counts.

Defining the Insect Pollinator Community Found in Iowa Corn and Soybean Fields: Implications for Pollinator Conservation.

PubMed

Wheelock, M J; Rey, K P; O'Neal, M E

2016-10-01

Although corn (Zea mays L.) and soybeans (Glycine max L.) do not require pollination, they offer floral resources used by insect pollinators. We asked if a similar community of insect pollinators visits these crops in central Iowa, a landscape dominated by corn and soybean production. We used modified pan traps (i.e., bee bowls) in both corn and soybean fields during anthesis and used nonmetric multidimensional scaling (NMS) to compare the communities found in the two crops. Summed across both crops, 6,704 individual insects were captured representing at least 60 species, morphospecies, or higher-level taxa. Thirty-four species were collected in both crops, 19 collected only in corn and seven were collected only in soybean. The most abundant taxa were Lasioglossum [Dialictus] spp., Agapostemon virescens Cresson, Melissodes bimaculata (Lepeletier), and Toxomerus marginatus (Say), which accounted for 65% of the insect pollinators collected from both crops. Although social bees (Apis mellifera L. and Bombus spp.) were found in both crops, they accounted for only 0.5% of all insects captured. The NMS analysis revealed a shared community of pollinators composed of mostly solitary, ground nesting bees. Many of these species have been found in other crop fields throughout North America. Although corn and soybean are grown in landscapes that are often highly disturbed, these data suggest that a community of pollinators can persist within them. We suggest approaches to conserving this community based on partnering with activities that aim to lessen the environmental impact of annual crop production. © 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.

A glycoprotein α-amylase inhibitor from Withania somnifera differentially inhibits various α-amylases and affects the growth and development of Tribolium castaneum.

PubMed

Kasar, Sainath S; Marathe, Kiran R; Bhide, Amey J; Herwade, Abhijeet P; Giri, Ashok P; Maheshwari, Vijay L; Pawar, Pankaj K

2017-07-01

Identification and characterisation of plant defensive molecules enrich our resources to design crop protection strategies. In particular, plant-derived proteinaceous inhibitor(s) of insect digestive enzymes appear to be a safe, sustainable and attractive option. A glycoprotein having non-competitive α-amylase inhibitory activity with a molecular weight of 8.3 kDa was isolated and purified from seeds of Withania somnifera α-amylase inhibitor (WSAI). Its mass spectrometry analysis revealed 59% sequence coverage with Wrightide II-type α-amylase inhibitor from Wrightia religiosa. A dose-dependent inhibition of α-amylases from Aspergillus oryzae, Bacillus subtilis, Helicoverpa armigera and Tribolium castaneum was recorded. Interestingly, WSAI did not inhibit human salivary α-amylase significantly. When adults of T. castaneum were fed with WSAI (1.6 mg g -1 ), decrease in consumption, growth and efficiency of conversion of ingested food was evident, along with over fourfold increases in feeding deterrence index. A decline in larval residual α-amylase activity after feeding of WSAI resulted in a reduction in longevity of T. castaneum. The study reflects the significance of WSAI in affecting the overall growth and development of T. castaneum. Pre- and post-harvest pest resistive capability makes WSAI a potential candidate for insect pest management. Further, the effectiveness of this inhibitor could be explored either in formulations or through a transgenic approach. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Enhanced Methanol Production in Plants Provides Broad Spectrum Insect Resistance

PubMed Central

Dixit, Sameer; Upadhyay, Santosh Kumar; Singh, Harpal; Sidhu, Om Prakash; Verma, Praveen Chandra; K, Chandrashekar

2013-01-01

Plants naturally emit methanol as volatile organic compound. Methanol is toxic to insect pests; but the quantity produced by most of the plants is not enough to protect them against invading insect pests. In the present study, we demonstrated that the over-expression of pectin methylesterase, derived from Arabidopsis thaliana and Aspergillus niger, in transgenic tobacco plants enhances methanol production and resistance to polyphagous insect pests. Methanol content in the leaves of transgenic plants was measured using proton nuclear spectroscopy (1H NMR) and spectra showed up to 16 fold higher methanol as compared to control wild type (WT) plants. A maximum of 100 and 85% mortality in chewing insects Helicoverpa armigera and Spodoptera litura larvae was observed, respectively when fed on transgenic plants leaves. The surviving larvae showed less feeding, severe growth retardation and could not develop into pupae. In-planta bioassay on transgenic lines showed up to 99 and 75% reduction in the population multiplication of plant sap sucking pests Myzus persicae (aphid) and Bemisia tabaci (whitefly), respectively. Most of the phenotypic characters of transgenic plants were similar to WT plants. Confocal microscopy showed no deformities in cellular integrity, structure and density of stomata and trichomes of transgenic plants compared to WT. Pollen germination and tube formation was also not affected in transgenic plants. Cell wall enzyme transcript levels were comparable with WT. This study demonstrated for the first time that methanol emission can be utilized for imparting broad range insect resistance in plants. PMID:24223989

Structure and transcription of the Helicoverpa armigera densovirus (HaDV2) genome and its expression strategy in LD652 cells.

PubMed

Xu, Pengjun; Graham, Robert I; Wilson, Kenneth; Wu, Kongming

2017-02-07

Densoviruses (DVs) are highly pathogenic to their hosts. However, we previously reported a mutualistic DV (HaDV2). Very little was known about the characteristics of this virus, so herein we undertook a series of experiments to explore the molecular biology of HaDV2 further. Phylogenetic analysis showed that HaDV2 was similar to members of the genus Iteradensovirus. However, compared to current members of the genus Iteradensovirus, the sequence identity of HaDV2 is less than 44% at the nucleotide-level, and lower than 36, 28 and 19% at the amino-acid-level of VP, NS1 and NS2 proteins, respectively. Moreover, NS1 and NS2 proteins from HaDV2 were smaller than those from other iteradensoviruses due to their shorter N-terminal sequences. Two transcripts of about 2.2 kb coding for the NS proteins and the VP proteins were identified by Northern Blot and RACE analysis. Using specific anti-NS1 and anti-NS2 antibodies, Western Blot analysis revealed a 78 kDa and a 48 kDa protein, respectively. Finally, the localization of both NS1 and NS2 proteins within the cell nucleus was determined by using Green Fluorescent Protein (GFP) labelling. The genome organization, terminal hairpin structure, transcription and expression strategies as well as the mutualistic relationship with its host, suggested that HaDV2 was a novel member of the genus Iteradensovirus within the subfamily Densovirinae.

Oral toxicity of beta-N-acetyl hexosaminidase to insects.

PubMed

Dowd, Patrick F; Johnson, Eric T; Pinkerton, T Scott

2007-05-02

Insect chitin is a potential target for resistance plant proteins, but plant-derived chitin-degrading enzymes active against insects are virtually unknown. Commercial beta-N-acetylhexosaminidase (NAHA), a chitin-degrading enzyme from jack bean Canavalia ensiformis, caused significant mortality of fall armyworm Spodoptera frugiperda larvae at 75 microg/gm, but no significant mortality was noted with Aspergillus niger NAHA. Maize Zea mays callus transformed to express an Arabidopsis thaliana clone that putatively codes for NAHA caused significantly higher mortality of cigarette beetle Lasioderma serricorne larvae and significantly reduced growth rates (as reflected by survivor weights) of S. frugiperda as compared to callus that expressed control cDNAs. Tassels from model line Hi-II maize (Z. mays) plants transformed with the NAHA gene fed to S. frugiperda caused significantly higher mortality than tassels transformed to express glucuronidase; mortality was significantly correlated with NAHA expression levels detected histochemically. Leaf disks from inbred Oh43 maize plants transformed with the NAHA gene on average had significantly less feeding by caterpillars than null transformants. Leaf disks of Oh43 transformants caused significant mortality of both S. frugiperda and corn earworm Helicoverpa zea larvae, which was associated with higher expression levels of NAHA detected by isoelectric focusing, histochemically, or with antibody. Overall, these results suggest that plant NAHA has a role in insect resistance. Introduction of NAHA genes or enhancement of activity through breeding or genetic engineering has the potential to significantly reduce insect damage and thereby indirectly reduce mycotoxins that are harmful to animals and people.

An evaluation of corn earworm damage and thresholds in soybean

NASA Astrophysics Data System (ADS)

Adams, Brian Patrick

Interactions between corn earworm, Helicoverpa zea (Boddie), and soybean, Glycine max L. (Merrill), were investigated in the Mid-South to evaluate thresholds and damage levels. Field studies were conducted in both indeterminate and determinate modern cultivars to evaluate damage, critical injury levels, and soybean response to simulated corn earworm injury. Field studies were also conducted to evaluate the response of indeterminate cultivars to infestations of corn earworm. Field studies were also conducted to investigate the relationship between pyrethroid insecticide application and corn earworm oviposition in soybean. Results of field studies involving simulated corn earworm damage indicated the need for a dynamic threshold that becomes more conservative as soybean phenology progressed through the reproductive growth stages. This suggested that soybean was more tolerant to fruit loss during the earlier reproductive stages and was able to compensate for fruit loss better during this time than at later growth stages. Results of field studies involving infestations of corn earworm indicated that current thresholds are likely too liberal. This resulted in economic injury level tables being constructed based upon a range of crop values and control costs, however, a general action threshold was also recommended for indeterminate soybean in the Mid-South. Field study results investigating the relationship of pyrethroid application and corn earworm oviposition indicated that even in the presence of an insecticide, corn earworm prefers to oviposit in the upper portion of the canopy, as well as on the leaves as opposed to all other plant parts, consistent with all previous literature.

Analysis of cross-resistance to Vip3 proteins in eight insect colonies, from four insect species, selected for resistance to Bacillus thuringiensis insecticidal proteins.

PubMed

Gomis-Cebolla, Joaquín; Wang, Yuequin; Quan, Yudong; He, Kanglai; Walsh, Tom; James, Bill; Downes, Sharon; Kain, Wendy; Wang, Ping; Leonard, Kathy; Morgan, Tom; Oppert, Brenda; Ferré, Juan

2018-05-16

Bacillus thuringiensis Vip3 proteins are synthesized and secreted during the vegetative growth phase. They are activated by gut proteases, recognize and bind to midgut receptors, form pores and lyse cells. We tested the susceptibility to Vip3Aa and Vip3Ca of Cry1A-, Cry2A-, Dipel- and Vip3-resistant insect colonies from different species to determine whether resistance to other insecticidal proteins confers cross-resistance to Vip3 proteins. As expected, the colonies resistant to Cry1A proteins, Dipel (Helicoverpa armigera, Trichoplusia ni, Ostrinia furnacalis and Plodia interpunctella) or Cry2Ab (H. armigera and T. ni) were not cross-resistant to Vip3 proteins. In contrast, H. armigera colonies resistant to Vip3Aa or Vip3Aa/Cry2Ab showed cross-resistance to the Vip3Ca protein. Moreover, the Vip3Ca protein was highly toxic to O. furnacalis (LC 50 not significantly different from that of Cry1Ab), whereas the Vip3Aa protein only showed moderate growth inhibition at the highest concentration tested (100 µg/g of diet). These results extend the cross-resistance studies between Vip3 and Cry proteins, show for the first time cross-resistance between proteins within the Vip3 subfamily, and points to O. furnacalis as a target for the Vip3Ca protein. Copyright © 2018 Elsevier Inc. All rights reserved.

Mass rearing and augmentative biological control evaluation of Rhynocoris fuscipes (Hemiptera: Reduviidae) against multiple pests of cotton.

PubMed

Tomson, Majesh; Sahayaraj, Kitherian; Kumar, Vivek; Avery, Pasco B; McKenzie, Cindy L; Osborne, Lance S

2017-08-01

Rhynocoris fuscipes (Fab.) (Hemiptera: Reduviidae) is a generalist predator of cotton pests and is commonly found inhabiting cotton-growing regions in southern India. With the goal of integrating this predator in standard management practices used against cotton pests on a commercial scale, (1) we developed a protocol for adult group rearing of this predator inside micro-environmental cages (MECs), and (2) we evaluated the biocontrol potential of mass-produced predators against cotton pests under potted and field conditions. Higher fecundity and adult longevity of R. fuscipes was recorded in the MECs than under natural growing conditions. The reduviid predator preferred stones and fallen leaves as hiding places in the MECs. The predator showed a higher biocontrol potential during the night hours against two pests, Phenacoccus solenopsis Tinsley and Dysdercus cingulatus (Fab.), than during the day under potted conditions. Under field conditions, R. fuscipes significantly reduced the population of Aphis gossypii Glover, P. solenopsis, D. cingulatus and Helicoverpa armigera (Hübner) by 28, 70, 29 and 50%, respectively. No negative impact of R. fuscipes was reported on other natural enemies present in the cotton agroecosystem. Significantly higher crop yield and cost benefit ratio were observed in R. fuscipes-released plots than in the control plots. The results suggest that R. fuscipes can be mass produced efficiently under controlled conditions in MECs, and used in an integrated management program for multiple cotton pests. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Competitive release and outbreaks of non-target pests associated with transgenic Bt cotton.

PubMed

Zeilinger, Adam R; Olson, Dawn M; Andow, David A

2016-06-01

The adoption of transgenic Bt cotton has, in some cases, led to environmental and economic benefits through reduced insecticide use. However, the distribution of these benefits and associated risks among cotton growers and cotton-growing regions has been uneven due in part to outbreaks of non-target or secondary pests, thereby requiring the continued use of synthetic insecticides. In the southeastern USA, Bt cotton adoption has resulted in increased abundance of and damage from stink bug pests, Euschistus servus and Nezara viridula (Heteroptera: Pentatomidae). While the impact of increased stink bug abundance has been well-documented, the causes have remained unclear. We hypothesize that release from competition with Bt-susceptible target pests may drive stink bug outbreaks in Bt cotton. We first examined the evidence for competitive release of stink bugs through meta-analysis of previous studies. We then experimentally tested if herbivory by Bt-susceptible Helicoverpa zea increases stink bug leaving rates and deters oviposition on non-Bt cotton. Consistent with previous studies, we found differences in leaving rates only for E servus, but we found that both species strongly avoided ovipositing on H. zea-damaged plants. Considering all available evidence, competitive release of stink bug populations in Bt cotton likely contributes to outbreaks, though the relative importance of competitive release remains an open question. Ecological risk assessments of Bt crops and other transgenic insecticidal crops would benefit from greater understanding of the ecological mechanisms underlying non-target pest outbreaks and greater attention to indirect ecological effects more broadly.

Characterization of a single-nucleocapsid nucleopolyhedrovirus of Thysanoplusia orichalcea L. (Lepidoptera: Noctuidae) from Indonesia.

PubMed

Cheng, X W; Carner, G R

2000-05-01

A single-nucleocapsid nucleopolyhedrovirus (NPV) isolated from Thysanoplusia orichalcea L. (Lepidoptera:Noctuidae) (ThorNPV) in Indonesia has tetrahedral occlusion bodies (OBs) with a width of 1. 22 microm (range = 0.803-1.931 microm). The length of the virion with an envelope averaged 0.29 and 0.23 microm without an envelope. ThorNPV was propagated in Pseudoplusia includens (Walker) and its authenticity was confirmed by sequence analysis of the polyhedrin gene of the ThorNPV produced in T. orichalcea and P. includens. Polyhedrin amino acid sequence analysis revealed that ThorNPV belongs to Group II of baculoviruses and is closely related to Trichoplusia ni single nucleocapsid NPV, sharing 97.6% sequence identity. Infectivity of ThorNPV against third instar P. includens was low, with a LD(50) value of 65,636 OBs/larva. Electron microscopy of infected tissues showed many polyhedra without virions embedded, which might explain the low virulence against P. includens. Differences in virion occlusion rates between individual cells in the same tissue suggested that the inoculum consisted of at least two variants that differed in the gene(s) controlling virion occlusion. In a host range test using the LD(50) value to P. includens against Spodoptera exigua, S. frugiperda, S. eridania, Anticarsia gemmatalis, Helicoverpa zea, Trichoplusia ni, and P. includens, P. includens was the only species infected. The virus infected primarily the fat body, tracheal epithelium, and hypodermis. The genomic size of the ThorNPV is 135 kb. Copyright 2000 Academic Press.

Discovery of an unusual biosynthetic origin for circular proteins in legumes

PubMed Central

Poth, Aaron G.; Colgrave, Michelle L.; Lyons, Russell E.; Daly, Norelle L.; Craik, David J.

2011-01-01

Cyclotides are plant-derived proteins that have a unique cyclic cystine knot topology and are remarkably stable. Their natural function is host defense, but they have a diverse range of pharmaceutically important activities, including uterotonic activity and anti-HIV activity, and have also attracted recent interest as templates in drug design. Here we report an unusual biosynthetic origin of a precursor protein of a cyclotide from the butterfly pea, Clitoria ternatea, a representative member of the Fabaceae plant family. Unlike all previously reported cyclotides, the domain corresponding to the mature cyclotide from this Fabaceae plant is embedded within an albumin precursor protein. We confirmed the expression and correct processing of the cyclotide encoded by the Cter M precursor gene transcript following extraction from C. ternatea leaf and sequencing by tandem mass spectrometry. The sequence was verified by direct chemical synthesis and the peptide was found to adopt a classic knotted cyclotide fold as determined by NMR spectroscopy. Seven additional cyclotide sequences were also identified from C. ternatea leaf and flower, five of which were unique. Cter M displayed insecticidal activity against the cotton budworm Helicoverpa armigera and bound to phospholipid membranes, suggesting its activity is modulated by membrane disruption. The Fabaceae is the third largest family of flowering plants and many Fabaceous plants are of huge significance for human nutrition. Knowledge of Fabaceae cyclotide gene transcripts should enable the production of modified cyclotides in crop plants for a variety of agricultural or pharmaceutical applications, including plant-produced designer peptide drugs. PMID:21593408

Sequence analysis, expression profiles and function of thioredoxin 2 and thioredoxin reductase 1 in resistance to nucleopolyhedrovirus in Helicoverpa armigera

PubMed Central

Zhang, Songdou; Li, Zhen; Nian, Xiaoge; Wu, Fengming; Shen, Zhongjian; Zhang, Boyu; Zhang, Qingwen; Liu, Xiaoxia

2015-01-01

The thioredoxin system, including NADPH, thioredoxin (Trx), and thioredoxin reductase (TrxR), plays significant roles in maintaining intracellular redox homeostasis and protecting organisms against oxidative damage. In this study, the characteristics and functions of H. armigera HaTrx2 and HaTrxR1 were identified. Sequence analysis showed that HaTrx2 and HaTrxR1 were both highly conserved and shared high sequence identity with other insect counterparts. The mRNA of HaTrx2 was expressed the highest in 5th instar 96 h and was mainly detected in heads and epidermis. The expression of HaTrxR1 was highly concentrated in 5th instar 72 h and 96 h, and higher in malpighian tube, midgut and hemocyte than other examined tissues. HaTrx2 and HaTrxR1 were markedly induced by various types of stress. HaTrx2- or HaTrxR1-knockdown increased ROS production in hemocytes and also increased the lipid damage in NPV infected H. armigera larvae. Furthermore, interference with expression of HaTrx2 or HaTrxR1 transcripts in H. armigera larvae resulted in increased sensitivity to NPV infection and shortened LT50 values. Our findings indicated that HaTrx2 and HaTrxR1 contribute to the susceptibility of H. armigera to NPV and also provided the theoretical basis for the in-depth study of insect thioredoxin system. PMID:26502992

Baseline sensitivity of lepidopteran corn pests in India to Cry1Ab insecticidal protein of Bacillus thuringiensis.

PubMed

Jalali, Sushil K; Lalitha, Yadavalli; Kamath, Subray P; Mohan, Komarlingam S; Head, Graham P

2010-08-01

Genetically engineered corn (Bt corn) expressing Bacillus thuringiensis Berliner insecticidal protein Cry1Ab is a biotechnological option being considered for management of lepidopteran corn pests in India. As a resistance management practice it was essential to determine the sensitivity of multiple populations of the stalk borer Chilo partellus (Swinhoe), pink borer Sesamia inferens (Walker) and the cob borer Helicoverpa armigera (Hübner) to Cry1Ab protein through bioassays. The insect populations were collected during growing seasons of Rabi 2005 (October 2005 to February 2006) and Kharif 2006 (May to September 2006). Multiple populations of the three lepidopteran corn pests were found to be susceptible to Cry1Ab. Median lethal concentrations (LC(50)) ranged between 0.008 and 0.068 microg Cry1Ab mL(-1) diet for 18 populations of C. partellus (across two seasons), between 0.12 and 1.99 microg mL(-1) for seven populations of H. armigera and between 0.46 and 0.56 microg mL(-1) for two populations of S. inferens. Dose-response concentrations for lethality and growth inhibition have been determined to mark baseline sensitivity of multiple populations of key lepidopteran corn pests in India to Cry1Ab protein. These benchmark values will be referenced while monitoring resistance to Cry1Ab should Bt corn hybrids expressing Cry1Ab be approved for commercial cultivation in India. Copyright (c) 2010 Society of Chemical Industry.

Nudiviruses and other large, double-stranded circular DNA viruses of invertebrates: new insights on an old topic.

PubMed

Wang, Yongjie; Jehle, Johannes A

2009-07-01

Nudiviruses (NVs) are a highly diverse group of large, circular dsDNA viruses pathogenic for invertebrates. They have rod-shaped and enveloped nucleocapsids, replicate in the nucleus of infected host cells, and possess interesting biological and molecular properties. The unassigned viral genus Nudivirus has been proposed for classification of nudiviruses. Currently, the nudiviruses comprise five different viruses: the palm rhinoceros beetle virus (Oryctes rhinoceros NV, OrNV), the Hz-1 virus (Heliothis zea NV-1, HzNV-1), the cricket virus (Gryllus bimaculatus NV, GbNV), the corn earworm moth Hz-2 virus (HzNV-2), and the occluded shrimp Monodon Baculovirus reassigned as Penaeus monodon NV (PmNV). Thus far, the genomes of OrNV, GbNV, HzNV-1 and HzNV-2 have been completely sequenced. They vary between 97 and 230kbp in size and encode between 98 and 160 open reading frames (ORFs). All sequenced nudiviruses have 33 ORFs in common. Strikingly, 20 of them are homologous to baculovirus core genes involved in RNA transcription, DNA replication, virion structural components and other functions. Another nine conserved ORFs are likely associated with DNA replication, repair and recombination, and nucleotide metabolism; one is homologous to baculovirus iap-3 gene; two are nudivirus-specific ORFs of unknown function. Interestingly, one nudivirus ORF is similar to polh/gran gene, encoding occlusion body protein matrix and being conserved in Alpha- Beta- and Gammabaculoviruses. Members of nudiviruses are closely related and form a monophyletic group consisting of two sister clades of OrNV/GbNV and HzNVs/PmNV. It is proposed that nudiviruses and baculoviruses derived from a common ancestor and are evolutionarily related to other large DNA viruses such as the insect-specific salivary gland hypertrophy virus (SGHV) and the marine white spot syndrome virus (WSSV).

Agonist-mediated activation of Bombyx mori diapause hormone receptor signals to extracellular signal-regulated kinases 1 and 2 through Gq-PLC-PKC-dependent cascade.

PubMed

Jiang, Xue; Yang, Jingwen; Shen, Zhangfei; Chen, Yajie; Shi, Liangen; Zhou, Naiming

2016-08-01

Diapause is a developmental strategy adopted by insects to survive in challenging environments such as the low temperatures of a winter. This unique process is regulated by diapause hormone (DH), which is a neuropeptide hormone that induces egg diapause in Bombyx mori and is involved in terminating pupal diapause in heliothis moths. An G protein-coupled receptor from the silkworm, B. mori, has been identified as a specific cell surface receptor for DH. However, the detailed information on the DH-DHR system and its mechanism(s) involved in the induction of embryonic diapause remains unknown. Here, we combined functional assays with various specific inhibitors to elucidate the DHR-mediated signaling pathways. Upon activation by DH, B. mori DHR is coupled to the Gq protein, leading to a significant increase of intracellular Ca(2+) and cAMP response element-driven luciferase activity in an UBO-QIC, a specific Gq inhibitor, sensitive manner. B. mori DHR elicited ERK1/2 phosphorylation in a dose- and time-dependent manner in response to DH. This effect was almost completely inhibited by co-incubation with UBO-QIC and was also significantly suppressed by PLC inhibitor U73122, PKC inhibitors Gö6983 and the Ca(2+) chelator EGTA. Moreover, DHR-induced activation of ERK1/2 was significantly attenuated by treatment with the Gβγ specific inhibitors gallein and M119K and the PI3K specific inhibitor Wortmannin, but not by the Src specific inhibitor PP2. Our data also demonstrates that the EGFR-transactivation pathway is not involved in the DHR-mediated ERK1/2 phosphorylation. Future efforts are needed to clarify the role of the ERK1/2 signaling pathway in the DH-mediated induction of B. mori embryonic diapause. Copyright © 2016 Elsevier Ltd. All rights reserved.

Combination of plant and insect eggs as food sources facilitates ovarian development in an omnivorous bug Apolygus lucorum (Hemiptera: Miridae).

PubMed

Yuan, Wei; Li, Wenjing; Li, Yunhe; Wu, Kongming G

2013-06-01

Diet nutrient is considered as an important regulatory factor for reproduction of insects. To understand the effect of different food sources on the reproductive physiology of Apolygus lucorum (Meyer-Dür), the ovarian development in adult females was investigated when they were fed on green beans (Gb), combination of green beans Phaseolus vulgaris L and Helicoverpa armigera eggs (GbHe), or H. armigera eggs (He). A female of A. lucorum has two ovaries, and each ovary contained seven yellowish ovarioles. Females fed on Gb or GbHe had larger ovaries and the ovarioles contained larger numbers of oocytes compared with those fed on He. Females in GeHe treatment has significantly higher number of follicles per ovary throughout the whole adult period compared with those in Gb or He treatment. Furthermore, the length of the best developed ovariole was affected by the diet type. The females fed on GbHe had the most developed ovarioles, with significantly longer ovarioles than those fed on Gb or He. A method was described to quantitatively score the degree of ovarian development in the current study. Similarly, the ovarian development scores were significantly higher for females in GbHe treatment than those in other two diet treatments. The ovarian development significantly delayed for females fed on He. Our results demonstrate that A. lucorum, as an omnivorous insect species, can acquire nutrients from both plant and animal origin food sources, and the combination of plants and animal food sources can significantly facilitate the ovary development of its females.

Transgenic Cotton Plants Expressing Double-stranded RNAs Target HMG-CoA Reductase (HMGR) Gene Inhibits the Growth, Development and Survival of Cotton Bollworms

PubMed Central

Tian, Geng; Cheng, Linlin; Qi, Xuewei; Ge, Zonghe; Niu, Changying; Zhang, Xianlong; Jin, Shuangxia

2015-01-01

RNA interference (RNAi) has been developed as a powerful technique in the research of functional genomics as well as plant pest control. In this report, double-stranded RNAs (dsRNA) targeting 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene, which catalyze a rate-limiting enzymatic reaction in the mevalonate pathway of juvenile hormone (JH) synthesis in cotton bollworm, was expressed in cotton plants via Agrobacterium tumefaciens-mediated transformation. PCR and Sothern analysis revealed the integration of HMGR gene into cotton genome. RT-PCR and qRT-PCR confirmed the high transcription level of dsHMGR in transgenic cotton lines. The HMGR expression both in transcription and translation level was significantly downregulated in cotton bollworms (helicoverpa armigera) larvae after feeding on the leaves of HMGR transgenic plants. The transcription level of HMGR gene in larvae reared on transgenic cotton leaves was as much as 80.68% lower than that of wild type. In addition, the relative expression level of vitellogenin (Vg, crucial source of nourishment for offspring embryo development) gene was also reduced by 76.86% when the insect larvae were fed with transgenic leaves. The result of insect bioassays showed that the transgenic plant harboring dsHMGR not only inhibited net weight gain but also delayed the growth of cotton bollworm larvae. Taken together, transgenic cotton plant expressing dsRNAs successfully downregulated HMGR gene and impaired the development and survival of target insect, which provided more option for plant pest control. PMID:26435695

Impact of Corn Earworm (Lepidoptera: Noctuidae) on Field Corn (Poales: Poaceae) Yield and Grain Quality.

PubMed

Bibb, Jenny L; Cook, Donald; Catchot, Angus; Musser, Fred; Stewart, Scott D; Leonard, Billy Rogers; Buntin, G David; Kerns, David; Allen, Tom W; Gore, Jeffrey

2018-05-28

Corn earworm, Helicoverpa zea (Boddie), commonly infests field corn, Zea mays (L.). The combination of corn plant biology, corn earworm behavior in corn ecosystems, and field corn value renders corn earworm management with foliar insecticides noneconomical. Corn technologies containing Bacillus thuringiensis (Bt) Berliner (Bacillales: Bacillaceae) were introduced that exhibit substantial efficacy against corn earworm and may reduce mycotoxin contamination in grain. The first generation Bt traits in field corn demonstrated limited activity on corn earworm feeding on grain. The pyramided corn technologies have greater cumulative protein concentrations and higher expression throughout the plant, so these corn traits should provide effective management of this pest. Additionally, reduced kernel injury may affect physical grain quality. Experiments were conducted during 2011-2012 to investigate corn earworm impact on field corn yield and grain quality. Treatments included field corn hybrids expressing the Herculex, YieldGard, and Genuity VT Triple Pro technologies. Supplemental insecticide treatments were applied every 1-2 d from silk emergence until silk senescence to create a range of injured kernels for each technology. No significant relationship between the number of corn earworm damaged kernels and yield was observed for any technology/hybrid. In these studies, corn earworm larvae did not cause enough damage to impact yield. Additionally, no consistent relationship between corn earworm damage and aflatoxin contamination was observed. Based on these data, the economic value of pyramided Bt corn traits to corn producers, in the southern United States, appears to be from management of other lepidopteran insect pests including European and southwestern corn borer.

Identification of multiple ear-colonizing insect and disease resistance in CIMMYT maize inbred lines with varying levels of silk maysin.

PubMed

Ni, Xinzhi; Krakowsky, Matthew D; Buntin, G David; Rector, Brian G; Guo, Baozhu; Snook, Maurice E

2008-08-01

Ninety four corn inbred lines selected from International Center for the Improvement of Maize and Wheat (CIMMYT) in Mexico were evaluated for levels of silk maysin in 2001 and 2002. Damage by major ear-feeding insects [i.e., corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae); maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae); brown stink bug, Euschistus servus (Say); southern green stink bugs, Nezara viridula (L.) (Heteroptera: Pentatomidae)], and common smut [Ustilago maydis DC (Corda)] infection on these inbred lines were evaluated in 2005 and 2006 under subtropical conditions at Tifton, GA. Ten inbred lines possessing good agronomic traits were also resistant to the corn earworm. The correlation between ear-feeding insect damage or smut infection and three phenotypic traits (silk maysin level, husk extension, and husk tightness of corn ears) was also examined. Corn earworm and stink bug damage was negatively correlated to husk extension, but not to either silk maysin levels or husk tightness. In combination with the best agronomic trait ratings that show the least corn earworm and stink bug damage, lowest smut infection rate, and good insect-resistant phenotypic traits (i.e., high maysin and good husk coverage and husk tightness), 10 best inbred lines (CML90, CML92, CML94, CML99, CML104, CML108, CML114, CML128, CML137, and CML373) were identified from the 94 lines examined. These selected inbred lines will be used for further examination of their resistance mechanisms and development of new corn germplasm that confers multiple ear-colonizing pest resistance.

Chlorantraniliprole as a candidate pesticide used in combination with the attracticides for lepidopteran moths.

PubMed

Liu, Yongqiang; Gao, Yu; Liang, Gemei; Lu, Yanhui

2017-01-01

Methomyl is currently used as a toxicant for the attracticide BioAttract in cotton and vegetables in China. However, methomyl is highly toxic to non-target organisms and a more environmental friendly acceptable alternative is required. Larvae of three lepidopteran insects Helicoverpa armigera, Agrotis ipsilon and Spodoptera litura are important pests of these crops in China. In the present study, the toxicity of 23 commonly used insecticides were tested on H. armigera, then tested the susceptibility of A. ipsilon and S. litura moths to the insecticides which were the most toxic to H. armigera, and the acute toxicity of the most efficacious insecticides were further investigated under laboratory conditions. Chlorantraniliprole, emamectin benzoate, spinetoram, spinosad and methomyl exhibited high levels of toxicity to H. armigera moths with a mortality of 86.67%, 91.11%, 73.33%, 57.78% and 80.00%, respectively, during 24 h period at the concentration of 1 mg a.i. L-1. Among these five insecticides, A. ipsilon and S. litura moths were more sensitive to chlorantraniliprole, emamectin benzoate and methomyl. The lethal time (LT50) values of chlorantraniliprole and methomyl were shorter than emamectin benzoate for all three lepidopteran moth species at 1000 mg a.i. L-1 compared to concentrations of 500, 100 and 1 mg a.i L-1. Chlorantraniliprole was found to have similar levels of toxicity and lethal time on the three lepidopteran moths tested to the standard methomyl, and therefore, can be used as an alternative insecticide to methomyl in the attracticide for controlling these pest species.

Chlorantraniliprole as a candidate pesticide used in combination with the attracticides for lepidopteran moths

PubMed Central

Liu, Yongqiang; Gao, Yu; Liang, Gemei

2017-01-01

Methomyl is currently used as a toxicant for the attracticide BioAttract in cotton and vegetables in China. However, methomyl is highly toxic to non-target organisms and a more environmental friendly acceptable alternative is required. Larvae of three lepidopteran insects Helicoverpa armigera, Agrotis ipsilon and Spodoptera litura are important pests of these crops in China. In the present study, the toxicity of 23 commonly used insecticides were tested on H. armigera, then tested the susceptibility of A. ipsilon and S. litura moths to the insecticides which were the most toxic to H. armigera, and the acute toxicity of the most efficacious insecticides were further investigated under laboratory conditions. Chlorantraniliprole, emamectin benzoate, spinetoram, spinosad and methomyl exhibited high levels of toxicity to H. armigera moths with a mortality of 86.67%, 91.11%, 73.33%, 57.78% and 80.00%, respectively, during 24 h period at the concentration of 1 mg a.i. L-1. Among these five insecticides, A. ipsilon and S. litura moths were more sensitive to chlorantraniliprole, emamectin benzoate and methomyl. The lethal time (LT50) values of chlorantraniliprole and methomyl were shorter than emamectin benzoate for all three lepidopteran moth species at 1000 mg a.i. L-1 compared to concentrations of 500, 100 and 1 mg a.i L-1. Chlorantraniliprole was found to have similar levels of toxicity and lethal time on the three lepidopteran moths tested to the standard methomyl, and therefore, can be used as an alternative insecticide to methomyl in the attracticide for controlling these pest species. PMID:28658277

Priming of anti-herbivore defense in tomato by arbuscular mycorrhizal fungus and involvement of the jasmonate pathway.

PubMed

Song, Yuan Yuan; Ye, Mao; Li, Chuan You; Wang, Rui Long; Wei, Xiao Chen; Luo, Shi Ming; Zeng, Ren Sen

2013-07-01

Mycorrhizas play a vital role in soil fertility, plant nutrition, and resistance to environmental stresses. However, mycorrhizal effects on plant resistance to herbivorous insects and the related mechanisms are poorly understood. This study evaluated effects of root colonization of tomato (Solanum lycopersicum Mill.) by arbuscular mycorrhizal fungi (AMF) Glomus mosseae on plant defense responses against a chewing caterpillar Helicoverpa arimigera. Mycorrhizal inoculation negatively affected larval performance. Real time RT-PCR analyses showed that mycorrhizal inoculation itself did not induce transcripts of most genes tested. However, insect feeding on AMF pre-inoculated plants resulted in much stronger defense response induction of four defense-related genes LOXD, AOC, PI-I, and PI-II in the leaves of tomato plants relative to non-inoculated plants. Four tomato genotypes: a wild-type (WT) plant, a jasmonic acid (JA) biosynthesis mutant (spr2), a JA-signaling perception mutant (jai1), and a JA-overexpressing 35S::PS plant were used to determine the role of the JA pathway in AMF-primed defense. Insect feeding on mycorrhizal 35S::PS plants led to higher induction of defense-related genes relative to WT plants. However, insect feeding on mycorrhizal spr2 and jai1 mutant plants did not induce transcripts of these genes. Bioassays showed that mycorrhizal inoculation on spr2 and jai1 mutants did not change plant resistance against H. arimigera. These results indicates that mycorrhizal colonization could prime systemic defense responses in tomato upon herbivore attack, and that the JA pathway is involved in defense priming by AMF.

Characterization of parasporin gene harboring Indian isolates of Bacillus thuringiensis.

PubMed

Lenina, N K; Naveenkumar, A; Sozhavendan, A E; Balakrishnan, N; Balasubramani, V; Udayasuriyan, V

2014-10-01

Bacillus thuringiensis (Bt) is popularly known as insecticidal bacterium. However, non-insecticidal Bt strains are more extensively available in natural environment than the insecticidal ones. Parasporin (PS) is a collection of genealogically heterogeneous Cry proteins synthesized in non-insecticidal isolates of Bt. An important character generally related with PS proteins is their strong cytocidal activity preferentially on human cancer cells of various origins. Identification and characterization of novel parasporin protein which are non-hemolytic and non-insecticidal but having selective anticancer activity raise the possibility of a novel application of Bt in medical field. In the present study, seven new indigenous isolates (T6, T37, T68, T98, T165, T186, and T461) of Bt showed variation in colony morphology, crystal characters and protein profiles with each other. Out of the seven new isolates screened for parasporin (ps) and cry genes, two of the new indigenous isolates (T98 and T186) of Bt showed the presence of ps4 gene. Partial ps4 gene was cloned from the two new isolates and the sequence of partial ps4 gene showed high homology with its holotype ps4Aa1. These two isolates were characterized based on the proteolytic processing of the inclusion proteins and the proteolytic products were found to be comparable to the PS4 reference strain A1470. The two isolates of Bt did not show toxicity toward Spodoptera litura and Helicoverpa armigera. Based on the results of this study, it can be concluded that the isolates T98 and T186 are parasporin producers.

Weakening density dependence from climate change and agricultural intensification triggers pest outbreaks: a 37-year observation of cotton bollworms

PubMed Central

Ouyang, Fang; Hui, Cang; Ge, Saiying; Men, Xin-Yuan; Zhao, Zi-Hua; Shi, Pei-Jian; Zhang, Yong-Sheng; Li, Bai-Lian

2014-01-01

Understanding drivers of population fluctuation, especially for agricultural pests, is central to the provision of agro-ecosystem services. Here, we examine the role of endogenous density dependence and exogenous factors of climate and human activity in regulating the 37-year population dynamics of an important agricultural insect pest, the cotton bollworm (Helicoverpa armigera), in North China from 1975 to 2011. Quantitative time-series analysis provided strong evidence explaining long-term population dynamics of the cotton bollworm and its driving factors. Rising temperature and declining rainfall exacerbated the effect of agricultural intensification on continuously weakening the negative density dependence in regulating the population dynamics of cotton bollworms. Consequently, ongoing climate change and agricultural intensification unleashed the tightly regulated pest population and triggered the regional outbreak of H. armigera in 1992. Although the negative density dependence can effectively regulate the population change rate to fluctuate around zero at stable equilibrium levels before and after outbreak in the 1992, the population equilibrium jumped to a higher density level with apparently larger amplitudes after the outbreak. The results highlight the possibility for exogenous factors to induce pest outbreaks and alter the population regulating mechanism of negative density dependence and, thus, the stable equilibrium of the pest population, often to a higher level, posing considerable risks to the provision of agro-ecosystem services and regional food security. Efficient and timely measures of pest management in the era of Anthropocene should target the strengthening and revival of weakening density dependence caused by climate change and human activities. PMID:25535553

Weakening density dependence from climate change and agricultural intensification triggers pest outbreaks: a 37-year observation of cotton bollworms.

PubMed

Ouyang, Fang; Hui, Cang; Ge, Saiying; Men, Xin-Yuan; Zhao, Zi-Hua; Shi, Pei-Jian; Zhang, Yong-Sheng; Li, Bai-Lian

2014-09-01

Understanding drivers of population fluctuation, especially for agricultural pests, is central to the provision of agro-ecosystem services. Here, we examine the role of endogenous density dependence and exogenous factors of climate and human activity in regulating the 37-year population dynamics of an important agricultural insect pest, the cotton bollworm (Helicoverpa armigera), in North China from 1975 to 2011. Quantitative time-series analysis provided strong evidence explaining long-term population dynamics of the cotton bollworm and its driving factors. Rising temperature and declining rainfall exacerbated the effect of agricultural intensification on continuously weakening the negative density dependence in regulating the population dynamics of cotton bollworms. Consequently, ongoing climate change and agricultural intensification unleashed the tightly regulated pest population and triggered the regional outbreak of H. armigera in 1992. Although the negative density dependence can effectively regulate the population change rate to fluctuate around zero at stable equilibrium levels before and after outbreak in the 1992, the population equilibrium jumped to a higher density level with apparently larger amplitudes after the outbreak. The results highlight the possibility for exogenous factors to induce pest outbreaks and alter the population regulating mechanism of negative density dependence and, thus, the stable equilibrium of the pest population, often to a higher level, posing considerable risks to the provision of agro-ecosystem services and regional food security. Efficient and timely measures of pest management in the era of Anthropocene should target the strengthening and revival of weakening density dependence caused by climate change and human activities.

A screening of five Bacillus thuringiensis Vip3A proteins for their activity against lepidopteran pests.

PubMed

Ruiz de Escudero, Iñigo; Banyuls, Núria; Bel, Yolanda; Maeztu, Mireya; Escriche, Baltasar; Muñoz, Delia; Caballero, Primitivo; Ferré, Juan

2014-03-01

Five Bacillus thuringiensis Vip3A proteins (Vip3Aa, Vip3Ab, Vip3Ad, Vip3Ae and Vip3Af) and their corresponding trypsin-activated toxins were tested for their toxicity against eight lepidopteran pests: Agrotis ipsilon, Helicoverpa armigera, Mamestra brassicae, Spodoptera exigua, Spodoptera frugiperda, Spodoptera littoralis, Ostrinia nubilalis and Lobesia botrana. Toxicity was first tested at a high dose at 7 and 10 days. No major differences were found when comparing protoxins vs. trypsin-activated toxins. The proteins that were active against most of the insect species were Vip3Aa, Vip3Ae and Vip3Af, followed by Vip3Ab. Vip3Ad was non-toxic to any of the species tested. Considering the results by insect species, A. ipsilon, S. frugiperda and S. littoralis were susceptible to Vip3Aa, Vip3Ab, Vip3Ae and Vip3Af; S. exigua was susceptible to Vip3Aa and Vip3Ae, and moderately susceptible to Vip3Ab; M. brassicae and L. botrana were susceptible to Vip3Aa, Vip3Ae and Vip3Af; H. armigera was moderately susceptible to Vip3Aa, Vip3Ae and Vip3Af, and O. nubilalis was tolerant to all Vip3 proteins tested, although it showed some susceptibility to Vip3Af. The results obtained will help to design new combinations of insecticidal protein genes in transgenic crops or in recombinant bacteria for the control of insect pests. Copyright © 2014 Elsevier Inc. All rights reserved.

Biocontrol Potential of Steinernema thermophilum and Its Symbiont Xenorhabdus indica Against Lepidopteran Pests: Virulence to Egg and Larval Stages.

PubMed

Kalia, Vinay; Sharma, Garima; Shapiro-Ilan, David I; Ganguly, Sudershan

2014-03-01

Under laboratory conditions, the biocontrol potential of Steinernema thermophilum was tested against eggs and larval stages of two important lepidopteran insect pests, Helicoverpa armigera and Spodoptera litura (polyphagous pests), as well as Galleria mellonella (used as a model host). In terms of host susceptibility of lepidopteran larvae to S. thermophilum, based on the LC50 36 hr after treatment, G. mellonella (LC50 = 16.28 IJ/larva) was found to be more susceptible than S. litura (LC50 = 85 IJ/larva), whereas neither host was found to be significantly different from H. armigera (LC50 = 54.68 IJ/larva). In addition to virulence to the larval stages, ovicidal activity up to 84% was observed at 200 IJ/50 and 100 eggs of H. armigera and S. litura, respectively. To our knowledge this is the first report of entomopathogenic nematode pathogenicity to lepidopteran eggs. Production of infective juvenile (IJ) nematodes/insect larva was also measured and found to be positively correlated with rate of IJ for H. armigera (r = 0.990), S. litura (r = 0.892), as well as G. mellonella (r = 0.834). Both Phase I and Phase II of symbiotic bacteria Xenorhabdus indica were tested separately against neonates of H. armigera and S. litura by feeding assays and found to be virulent to the target pests; phase variation did not affect the level of virulence. Thus S. thermophilum as well as the nematode's symbiotic bacteria applied separately have the potential to be developed as biocontrol agents for key lepidopteran pests.

Biological and molecular characterization of a multicapsid nucleopolyhedrovirus from Thysanoplusia orichalcea (L.) (Lepidoptera: Noctuidae).

PubMed

Cheng, Xiao-Wen; Carner, Gerald R; Lange, Martin; Jehle, Johannes A; Arif, Basil M

2005-02-01

A multicapsid nucleopolyhedrovirus (ThorMNPV) that was co-isolated with a single nucleocapid ThorSNPV from mixed infected larvae of Thysanoplusia orichalcea L. (Lepidoptea: Noctuidae) is characterized. Scanning electron microscopy of ThorMNPV showed a dodecahedral-shaped occlusion body (OB). The occluded virions contained one to as many as eight nucleocapsids/virion. Virion band profiles in gradient centrifugation were consistent in at least 10 rounds of centrifugation from different virion sample preparations. The ThorMNPV had high virulence to third instar Trichoplusia ni and Pseudoplusia includens with LD50 values of 17 and 242OBs per larva, respectively. However, ThorMNPV did not cause mortality in Spodoptera exigua, Spodoptera frugiperda, Spodoptera eridania, Anticarsia gemmatalis, and Helicoverpa zea. ThorMNPV replicates in cells of various tissues such as the fat body and tracheal epithelium cells. T. ni High 5 cells were permissive to ThorMNPV in terms of infection and viral DNA transfection, but SF-21 was less permissive and the infection process was slower. Production of OBs by ThorMNPV in the nuclei of SF-21 was not well pronounced. The genome size of ThorMNPV was estimated to be 136 kb. The polyhedrin gene open reading frame (ORF) was cloned and completely sequenced. The promoter sequence is identical to that of Autographa californica MNPV. Phylogenetic analyses using partial sequences of the polh, lef-8, and lef-9 revealed that ThorMNPV is a member of the Group I NPVs and is related but distinct from the AcMNPV/Rachiplusia ou NPV/Bombyx mori NPV cluster.

Residual and Systemic Efficacy of Chlorantraniliprole and Flubendiamide Against Corn Earworm (Lepidoptera: Noctuidae) in Soybean

PubMed Central

Adams, A.; Gore, J.; Catchot, A.; Musser, F.; Cook, D.; Krishnan, N.; Irby, T.

2016-01-01

Experiments were conducted in Mississippi from 2013 to 2015 to determine the systemic and residual efficacy of chlorantraniliprole and flubendiamide against corn earworm, Helicoverpa zea (Boddie), in soybean. Both insecticides were applied at V4 and R3. Ten leaves that were present at the time of application and 10 newly emerged leaves that were not present at the time of application were collected to measure residual and systemic efficacy, respectively. Ten pods were removed from each plot at R5.5. For all assays, corn earworm larvae were placed on plant material. Chlorantraniliprole appeared to provide systemic control of H. zea, but was dependent on soybean growth stage at the time of application. In the V4 experiment, chlorantraniliprole resulted in greater mortality than the control on new leaves at 7 d after treatment, but not at 14 d. In the R3 experiment, chlorantraniliprole resulted in greater than 90% mortality on new leaves at all evaluation intervals. Mortality of H. zea on new leaves was <17% for flubendiamide and was not different than the control. Both insecticides resulted in significant mortality of H. zea on leaves that were present at the time of application for at least 31 d after application. Chlorantraniliprole resulted in greater mortality than flubendiamide at 24 and 31 d. Neither insecticide resulted in mortality of H. zea feeding on reproductive structures. These results suggest that chlorantraniliprole moves to new vegetative structures but not to reproductive structures of soybean, and that flubendiamide does not move systemically. PMID:27707947

Two Year Field Study to Evaluate the Efficacy of Mamestra brassicae Nucleopolyhedrovirus Combined with Proteins Derived from Xestia c-nigrum Granulovirus

PubMed Central

Goto, Chie; Mukawa, Shigeyuki; Mitsunaga, Takayuki

2015-01-01

Japan has only three registered baculovirus biopesticides despite its long history of studies on insect viruses. High production cost is one of the main hindrances for practical use of baculoviruses. Enhancement of insecticidal effect is one possible way to overcome this problem, so there have been many attempts to develop additives for baculoviruses. We found that alkaline soluble proteins of capsules (GVPs) of Xestia c-nigrum granulovirus can increase infectivity of some viruses including Mamestra brassicae nucleopolyhedrovirus (MabrNPV), and previously reported that MabrNPV mixed with GVPs was highly infectious to three important noctuid pests of vegetables in the following order, Helicoverpa armigera, M. brassicae, and Autographa nigrisigna. In this study, small-plot experiments were performed to assess concentrations of MabrNPV and GVPs at three cabbage fields and a broccoli field for the control of M. brassicae. In the first experiment, addition of GVPs (10 µg/mL) to MabrNPV at 106 OBs/mL resulted in a significant increase in NPV infection (from 53% to 66%). In the second experiment, the enhancing effect of GVP on NPV infection was confirmed at 10-times lower concentrations of MabrNPV. In the third and fourth experiments, a 50% reduction in GVPs (from 10 µg/mL to 5 µg/mL) did not result in a lowering of infectivity of the formulations containing MabrNPV at 105 OBs/mL. These results indicate that GVPs are promising additives for virus insecticides. PMID:25760139

Female pheromones modulate flight muscle activation patterns during preflight warm-up.

PubMed

Crespo, José G; Vickers, Neil J; Goller, Franz

2013-08-01

At low ambient temperature Helicoverpa zea male moths engage in warm-up behavior prior to taking flight in response to an attractive female pheromone blend. Male H. zea warm up at a faster rate when sensing the attractive pheromone blend compared with unattractive blends or blank controls (Crespo et al. 2012), but the mechanisms involved in this olfactory modulation of the heating rate during preflight warm-up are unknown. Here, we test three possible mechanisms for increasing heat production: 1) increased rate of muscle contraction; 2) reduction in mechanical movement by increased overlap in activation of the antagonistic flight muscles; and 3) increased activation of motor units. To test which mechanisms play a role, we simultaneously recorded electrical activation patterns of the main flight muscles (dorsolongitudinal and dorsoventral muscles), wing movement, and thoracic temperature in moths exposed to both the attractive pheromone blend and a blank control. Results indicate that the main mechanism responsible for the observed increase in thoracic heating rate with pheromone stimulation is the differential activation of motor units during each muscle contraction cycle in both antagonistic flight muscles. This additional activation lengthens the contracted state within each cycle and thus accounts for the greater heat production. Interestingly, the rate of activation (frequency of contraction cycles) of motor units, which is temperature dependent, did not vary between treatments. This result suggests that the activation rate is determined by a temperature-dependent oscillator, which is not affected by the olfactory stimulus, but activation of motor units is modulated during each cycle.

Female pheromones modulate flight muscle activation patterns during preflight warm-up

PubMed Central

Vickers, Neil J.; Goller, Franz

2013-01-01

At low ambient temperature Helicoverpa zea male moths engage in warm-up behavior prior to taking flight in response to an attractive female pheromone blend. Male H. zea warm up at a faster rate when sensing the attractive pheromone blend compared with unattractive blends or blank controls (Crespo et al. 2012), but the mechanisms involved in this olfactory modulation of the heating rate during preflight warm-up are unknown. Here, we test three possible mechanisms for increasing heat production: 1) increased rate of muscle contraction; 2) reduction in mechanical movement by increased overlap in activation of the antagonistic flight muscles; and 3) increased activation of motor units. To test which mechanisms play a role, we simultaneously recorded electrical activation patterns of the main flight muscles (dorsolongitudinal and dorsoventral muscles), wing movement, and thoracic temperature in moths exposed to both the attractive pheromone blend and a blank control. Results indicate that the main mechanism responsible for the observed increase in thoracic heating rate with pheromone stimulation is the differential activation of motor units during each muscle contraction cycle in both antagonistic flight muscles. This additional activation lengthens the contracted state within each cycle and thus accounts for the greater heat production. Interestingly, the rate of activation (frequency of contraction cycles) of motor units, which is temperature dependent, did not vary between treatments. This result suggests that the activation rate is determined by a temperature-dependent oscillator, which is not affected by the olfactory stimulus, but activation of motor units is modulated during each cycle. PMID:23699056

cDNA cloning and sequence determination of the pheromone biosynthesis activating neuropeptide from the seabuckthorn carpenterworm, Holcocerus hippophaecolus (Lepidoptera: Cossidae).

PubMed

Li, Juan; Zhou, Jiao; Sun, Rongbo; Zhang, Haolin; Zong, Shixiang; Luo, Youqing; Sheng, Xia; Weng, Qiang

2013-04-01

The PBAN (pheromone biosynthesis activating neuropeptide)/pyrokinin peptides comprise a major neuropeptide family characterized by a common FXPRL amide at the C-terminus. These peptides are actively involved in many essential endocrine functions. For the first time, we reported the cDNA cloning and sequence determination of the PBAN from the seabuckthorn carpenterworm, Holcocerus hippophaecolus, by using rapid amplification of cDNA ends. The full-length cDNA of Hh-DH-PBAN contained five peptides: diapause hormone (DH) homolog, α-neuropeptide (NP), β-NP, PBAN, and γ-NP. All of the peptides were amidated at their C-terminus and shared a conserved motif, FXPR (or K) L. Moreover, Hh-DH-PBAN had high homology to the other members of the PBAN peptide family: 56% with Manduca sexta, 66% with Bombyx mori, 77% with Helicoverpa zea, and 47% with Plutella xylostella. Phylogenetic analysis revealed that Hh-DH-PBAN was closely related to PBANs from Noctuidae, demonstrated by the relatively higher similarity compared with H. zea. In addition, real-time quantitative PCR (qRT-PCR) analysis showed that Hh-DH-PBAN mRNA expression peaked in the brain-subesophageal ganglion (Br-SOG) complex, and was also detected at high levels during larval and adult stages. The expression decreased significantly after pupation. These results provided information concerning molecular structure characteristics of Hh-DH-PBAN, whose expression profile suggested that the Hh-DH-PBAN gene might be correlated with larval development and sex pheromone biosynthesis in females of the H. hippophaecolus. 2013 Wiley Periodicals, Inc

Intraear Compensation of Field Corn, Zea mays, from Simulated and Naturally Occurring Injury by Ear-Feeding Larvae.

PubMed

Steckel, S; Stewart, S D

2015-06-01

Ear-feeding larvae, such as corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), can be important insect pests of field corn, Zea mays L., by feeding on kernels. Recently introduced, stacked Bacillus thuringiensis (Bt) traits provide improved protection from ear-feeding larvae. Thus, our objective was to evaluate how injury to kernels in the ear tip might affect yield when this injury was inflicted at the blister and milk stages. In 2010, simulated corn earworm injury reduced total kernel weight (i.e., yield) at both the blister and milk stage. In 2011, injury to ear tips at the milk stage affected total kernel weight. No differences in total kernel weight were found in 2013, regardless of when or how much injury was inflicted. Our data suggested that kernels within the same ear could compensate for injury to ear tips by increasing in size, but this increase was not always statistically significant or sufficient to overcome high levels of kernel injury. For naturally occurring injury observed on multiple corn hybrids during 2011 and 2012, our analyses showed either no or a minimal relationship between number of kernels injured by ear-feeding larvae and the total number of kernels per ear, total kernel weight, or the size of individual kernels. The results indicate that intraear compensation for kernel injury to ear tips can occur under at least some conditions. © 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.

Regional pest suppression associated with widespread Bt maize adoption benefits vegetable growers.

PubMed

Dively, Galen P; Venugopal, P Dilip; Bean, Dick; Whalen, Joanne; Holmstrom, Kristian; Kuhar, Thomas P; Doughty, Hélène B; Patton, Terry; Cissel, William; Hutchison, William D

2018-03-27

Transgenic crops containing the bacterium Bacillus thuringiensis (Bt) genes reduce pests and insecticide usage, promote biocontrol services, and economically benefit growers. Area-wide Bt adoption suppresses pests regionally, with declines expanding beyond the planted Bt crops into other non-Bt crop fields. However, the offsite benefits to growers of other crops from such regional suppression remain uncertain. With data spanning 1976-2016, we demonstrate that vegetable growers benefit via decreased crop damage and insecticide applications in relation to pest suppression in the Mid-Atlantic United States. We provide evidence for the regional suppression of Ostrinia nubilalis (Hübner), European corn borer, and Helicoverpa zea (Boddie), corn earworm, populations in association with widespread Bt maize adoption (1996-2016) and decreased economic levels for injury in vegetable crops [peppers ( Capsicum annuum L.), green beans ( Phaseolus vulgaris L.), and sweet corn ( Zea mays L., convar. saccharata )] compared with the pre-Bt period (1976-1995). Moth populations of both species significantly declined in association with widespread Bt maize (field corn) adoption, even as increased temperatures buffered the population reduction. We show marked decreases in the number of recommended insecticidal applications, insecticides applied, and O. nubilalis damage in vegetable crops in association with widespread Bt maize adoption. These offsite benefits to vegetable growers in the agricultural landscape have not been previously documented, and the positive impacts identified here expand on the reported ecological effects of Bt adoption. Our results also underscore the need to account for offsite economic benefits of pest suppression, in addition to the direct economic benefits of Bt crops.

Baseline sensitivity of maize borers in India to the Bacillus thuringiensis insecticidal proteins Cry1A.105 and Cry2Ab2.

PubMed

Jalali, Sushil K; Yadavalli, Lalitha; Ojha, Rakshit; Kumar, Pradyumn; Sulaikhabeevi, Suby B; Sharma, Reema; Nair, Rupa; Kadanur, Ravi C; Kamath, Subray P; Komarlingam, Mohan S

2015-08-01

Among the major pests of maize in India are two stem borers, Chilo partellus (Swinhoe) and Sesamia inferens (Walker), and an earworm, Helicoverpa armigera (Hübner). As a pest control strategy, transgenic Bacillus thuringiensis (Bt) maize hybrids are undergoing regulatory trials in India. We have determined the sensitivity of the target lepidopterans to the insecticidal Bt proteins expressed in Bt maize, as this determines product efficacy and the resistance management strategy to be adopted. Maize hybrids with event MON89034 express two insecticidal Bt proteins, Cry1A.105 and Cry2Ab2. Sensitivity profiles of 53 populations of C. partellus, 21 populations of S. inferens and 21 populations of H. armigera, collected between 2008 and 2013 from maize-growing areas in India, to Cry1A.105 and Cry2Ab2 proteins were generated through dose-response assays. Cry1A.105 protein was the most effective to neonates of C. partellus (mean MIC90 range 0.30-1.0 µg mL(-1) ) and H. armigera (mean MIC90 range 0.71-8.22 µg mL(-1) ), whereas Cry2Ab2 (mean MIC90 range 0.65-1.70 µg mL(-1) ) was the most effective to S. inferens. Populations of C. partellus, S. inferens and H. armigera were susceptible to the Bt proteins Cry1A.105 and Cry2Ab2. The Bt sensitivity data will serve as precommercialisation benchmarks for resistance monitoring purposes. © 2014 Society of Chemical Industry.

Breeding birds in managed forests on public conservation lands in the Mississippi Alluvial Valley

USGS Publications Warehouse

Twedt, Daniel J.; Wilson, R. Randy

2017-01-01

Managers of public conservation lands in the Mississippi Alluvial Valley have implemented forest management strategies to improve bottomland hardwood habitat for target wildlife species. Through implementation of various silvicultural practices, forest managers have sought to attain forest structural conditions (e.g., canopy cover, basal area, etc.) within values postulated to benefit wildlife. We evaluated data from point count surveys of breeding birds on 180 silviculturally treated stands (1049 counts) that ranged from 1 to 20 years post-treatment and 134 control stands (676 counts) that had not been harvested for >20 years. Birds detected during 10-min counts were recorded within four distance classes and three time intervals. Avian diversity was greater on treated stands than on unharvested stands. Of 42 commonly detected species, six species including Prothonotary Warbler (Prothonotaria citrea) and Acadian Flycatcher (Empidonax virescens) were indicative of control stands. Similarly, six species including Indigo Bunting (Passerina cyanea) and Yellow-breasted Chat (Icteria virens) were indicative of treated stands. Using a removal model to assess probability of detection, we evaluated occupancy of bottomland forests at two spatial scales (stands and points within occupied stands). Wildlife-forestry treatment improved predictive models of species occupancy for 18 species. We found years post treatment (range = 1–20), total basal area, and overstory canopy were important species-specific predictors of occupancy, whereas variability in basal area was not. In addition, we used a removal model to estimate species-specific probability of availability for detection, and a distance model to estimate effective detection radius. We used these two estimated parameters to derive species densities and 95% confidence intervals for treated and unharvested stands. Avian densities differed between treated and control stands for 16 species, but only Common Yellowthroat (Geothlypis trichas) and Yellow-breasted Chat had greater densities on treated stands.

Ecology of mangroves in the Jewfish Chain, Exuma, Bahamas

USGS Publications Warehouse

Wilcox, L. V.; Yocom, Thomas G.; Forbes, A. M.

1976-01-01

The structure and function of mangrove communities in the Jewfish Chain, Exumas, Bahamas, were investigated for 3-1/2 years. Mangrove vegetation in the Jewfish Chain is similar to that in all the Caribbean-Florida area; Rhizophora mangle L. dominates and is interspersed with Avicennia germinans (L.) Lamk. and Laguncularia racemosa (L.) Gaertn. There is no apparent zonation of these three species. The mangrove communities in the Jewfish Chain occur only where they are protected from prevailing winds, storms, and tides, although all are periodically devastated by hurricanes. We found little or no evidence of coast building within these protected locations. The importance of the mangroves appears to be in providing protection and food for other flora and fauna within this unique ecosystem. Twenty-four species of algae were found in the mangroves, 9 of which had not previously been reported from the Bahamas. Distribution of these algae appears to be correlated to incident solar radiation, desiccation, and tide level. A total of 56 species of fish were found in the mangroves, 2 of which were not previously known from the Bahamas. Many fish taken were juveniles, suggesting that mangroves are a nursery ground for numerous species. Nine species of molluscs were found. Each species had a distinct distribution pattern relative to distance from the seaward edge of the mangroves, as well as a distinct vertical distribution pattern. Seventeen species of decapod crustaceans were recorded. Though several species of birds were noted in the mangroves, three species were most abundant: the white-crowned pigeon (Columba leucocephala) uses the mangrove for nesting but feeds in nearby shrub-thorn communities; the gray kingbird (Tyrannus dominicensis) and green heron (Butorides virescens) nest and feed in the mangroves. Our data do not completely describe a stereotyped mangrove community in the Bahamas, but they do give an indication of community structure and suggest several aspects of function.

Responses of Cerambycidae and Other Insects to Traps Baited With Ethanol, 2,3-Hexanediol, and 3,2-Hydroxyketone Lures in North-Central Georgia.

PubMed

Miller, D R; Crowe, C M; Mayo, P D; Silk, P J; Sweeney, J D

2015-10-01

In north-central Georgia, 13 species of woodboring beetles (Coleoptera: Cerambycidae: Cerambycinae) were attracted to multiple-funnel traps baited with ethanol and one of the following pheromones: (1) racemic 3-hydroxyhexan-2-one; (2) racemic 3-hydroxyoctan-2-one; and (3) syn-2,3-hexanediol. The following species were attracted to traps baited with ethanol and 3-hydroxyhexan-2-one: Anelaphus pumilus (Newman), Eburia quadrigeminata (Say), Euderces pini (Olivier), Knulliana cincta (Drury), Neoclytus mucronatus (F.), Neoclytus scutellaris (Olivier), and Xylotrechus colonus (F.). Clytus marginicollis Castelnau & Gory, and Anelaphus parallelus (Newman) were attracted to traps baited with ethanol and 3-hydroxyoctan-2-one, whereas traps baited with ethanol and syn-2,3-hexanediol were attractive to Anelaphus villosus (F.), A. parallelus, Neoclytus acuminatus (F.), Neoclytus jouteli jouteli Davis, and Megacyllene caryae (Gahan). Ethanol enhanced catches of seven cerambycid species in traps baited with syn-2,3-hexanediol and 3,2-hydroxyketones. Catches of bark and ambrosia beetles (Curculionidae: Scolytinae) in ethanol-baited traps were largely unaffected by the addition of syn-2,3-hexanediol and 3,2-hydroxyketone lures, except for two species. The mean catches of Hypothenemus rotundicollis Wood & Bright and Dryoxylon onoharaensum (Murayama) in ethanol-baited traps increased and decreased, respectively, with the addition of racemic 3-hydroxyoctan-2-one. Traps baited with ethanol and syn-2,3-hexanediol were attractive to Xylobiops basilaris (Say) (Bostrichidae) and Chariessa pilosa (Forster) (Cleridae), whereas Temnoscheila virescens (F.) (Trogossitidae) were attracted to traps baited with ethanol and 3-hydroxyhexan-2-one. The assassin bug, Apiomerus crassipes (F.) (Hemiptera: Reduviidae), was attracted to traps baited with ethanol and 3,2-hydroxyketones. Published by Oxford University Press on behalf of Entomological Society of America 2015. This work is written by US Government employees and is in the public domain in the US.

Toxicity of a formulation of the insecticide indoxacarb to the tarnished plant bug, Lygus lineolaris (Hemiptera: Miridae), and the big-eyed bug, Geocoris punctipes (Hemiptera: Lygaeidae).

PubMed

Tillman, P Glynn; Hammes, Glenn G; Sacher, Matthew; Connair, Michael; Brady, E Angela; Wing, Keith D

2002-01-01

Indoxacarb is a new oxadiazine insecticide that has shown outstanding field insecticidal activity. The toxicity of a 145 g litre-1 indoxacarb SC formulation (Steward) was studied on the tarnished plant bug Lygus lineolaris and the big-eyed bug Geocoris punctipes. Both insect species responded very similarly to indoxacarb in topical, tarsal contact and plant feeding toxicity studies. The topical LD50 of the formulation was c 35 ng AI per insect for both species. Prolonged tarsal contact with dry indoxacarb residues did not result in mortality for either insect species. However, both species were susceptible to feeding through dried residues of indoxacarb after spraying on young cotton plants. Feeding on water-washed plants resulted in lower mortality than that observed with unwashed plants, and toxicity declined even more dramatically after a, detergent rinse, indicating that much of the indoxacarb probably resides on the cotton leaf surface or in the waxy cuticle. These results were corroborated by HPLC-mass spectrometry measurements of indoxacarb residues on the plants. Greater mortality for both species was observed in a higher relative humidity environment. Higher levels of accumulated indoxacarb and its active metabolite were detected in dead G punctipes than in L lineolaris after feeding on sprayed, unwashed plants. When female G punctipes ate indoxacarb-treated Heliothis zea eggs, there was significant toxicity. However, only c 15% of the females consumed indoxacarb-treated eggs, and the rest of the females showed a significant diminution of feeding in response to the insecticide. Cotton field studies have shown that indoxacarb treatments at labelled rates lead to a dramatic decline in L lineolaris, with negligible declines in beneficial populations. A major route of intoxication of L lineolaris in indoxacarb-treated cotton fields thus appears to be via oral, and not cuticular, uptake of residues from treated cotton plants. The mechanisms for selectivity/safety for G punctipes are currently under investigation and may be a combination of differential feeding behavior and diminution of feeding by females exposed to indoxacarb-treated eggs.

The Genome of Gryllus bimaculatus Nudivirus Indicates an Ancient Diversification of Baculovirus-Related Nonoccluded Nudiviruses of Insects▿

PubMed Central

Wang, Yongjie; Kleespies, Regina G.; Huger, Alois M.; Jehle, Johannes A.

2007-01-01

The Gryllus bimaculatus nudivirus (GbNV) infects nymphs and adults of the cricket Gryllus bimaculatus (Orthoptera: Gryllidae). GbNV and other nudiviruses such as Heliothis zea nudivirus 1 (HzNV-1) and Oryctes rhinoceros nudivirus (OrNV) were previously called “nonoccluded baculoviruses” as they share some similar structural, genomic, and replication aspects with members of the family Baculoviridae. Their relationships to each other and to baculoviruses are elucidated by the sequence of the complete genome of GbNV, which is 96,944 bp, has an AT content of 72%, and potentially contains 98 predicted protein-coding open reading frames (ORFs). Forty-one ORFs of GbNV share sequence similarities with ORFs found in OrNV, HzNV-1, baculoviruses, and bacteria. Most notably, 15 GbNV ORFs are homologous to the baculovirus core genes, which are associated with transcription (lef-8, lef-9, lef-4, vlf-1, and lef-5), replication (dnapol), structural proteins (p74, pif-1, pif-2, pif-3, vp91, and odv-e56), and proteins of unknown function (38K, ac81, and 19kda). Homologues to these baculovirus core genes have been predicted in HzNV-1 as well. Six GbNV ORFs are homologous to nonconserved baculovirus genes dnaligase, helicase 2, rr1, rr2, iap-3, and desmoplakin. However, the remaining 57 ORFs revealed no homology or poor similarities to the current gene databases. No homologous repeat (hr) sequences but fourteen short direct repeat (dr) regions were detected in the GbNV genome. Gene content and sequence similarity suggest that the nudiviruses GbNV, HzNV-1, and OrNV form a monophyletic group of nonoccluded double-stranded DNA viruses, which separated from the baculovirus lineage before this radiated into dipteran-, hymenopteran-, and lepidopteran-specific clades of occluded nucleopolyhedroviruses and granuloviruses. The accumulated information on the GbNV genome suggests that nudiviruses form a highly diverse and phylogenetically ancient sister group of the baculoviruses, which have evolved in a variety of highly divergent host orders. PMID:17360757

Intraguild Competition of Three Noctuid Maize Pests.

PubMed

Bentivenha, J P F; Baldin, E L L; Hunt, T E; Paula-Moraes, S V; Blankenship, E E

2016-08-01

The western bean cutworm Striacosta albicosta (Smith), the fall armyworm Spodoptera frugiperda (J. E. Smith), and the corn earworm Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) are among the major lepidopteran pests of maize in the United States, belonging to the same guild and injuring the reproductive tissues of this crop. Here, intraguild competition of these lepidopterans on non-Bt maize was evaluated through survival analysis of each species under laboratory and field conditions. Competition scenarios were carried out in arenas containing maize silk or ear tissue, using larvae on different stadium of development. Fitness cost competition studies were conducted to examine the influence of intraguild competition and cannibalism and predation rates on larval development. The survival of S. albicosta competing with the other species was significantly lower than in intraspecific competition, even when the larvae were more developed than the competitor. For S. frugiperda, survival remained high in the different competition scenarios, except when competing in a smaller stadium with H. zea Larvae of H. zea had a high rate of cannibalism, higher survival when competing against S. albicosta than S. frugiperda, and reduced survival when the H. zea larvae were at the same development stadium or smaller than the competitors. Based on fitness cost results, the absence of a competitor for the feeding source may confer an advantage to the larval development of S. frugiperda and H. zea Our data suggest that S. frugiperda has a competitive advantage against the other species, while S. albicosta has the disadvantage in the intraguild competition on non-Bt maize. © 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.

Impact of applying edible oils to silk channels on ear pests of sweet corn.

PubMed

Ni, Xinzhi; Sparks, Alton N; Riley, David G; Li, Xianchun

2011-06-01

The impact of applying edible oils to corn silks on ear-feeding insects in sweet corn, Zea mays L., production was evaluated in 2006 and 2007. Six edible oils used in this experiment were canola, corn, olive, peanut, sesame, and soybean. Water and two commercial insecticidal oils (Neemix neem oil and nC21 Sunspray Ultrafine, a horticultural mineral oil) were used as the controls for the experiment. Six parameters evaluated in this experiment were corn earworm [Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae)] damage rating, the number of sap beetle [Carpophilus spp. (Coleoptera: Nitidulidae)] adults and larvae, the number of corn silk fly (or picture-winged fly) (Diptera: Ulidiidae) larvae, common smut [Ustilago maydis (D.C.) Corda] infection rate, and corn husk coverage. Among the two control treatments, neem oil reduced corn earworm damage at both pre- and postpollination applications in 2006, but not in 2007, whereas the mineral oil applied at postpollination treatments reduced corn earworm damage in both years. The mineral oil also reduced the number of sap beetle adults, whereas the neem oil applied at postpollination attracted the most sap beetle adults in 2007. Among the six edible oil treatments, the corn and sesame oils applied at postpollination reduced corn earworm damage only in 2007. The application of the peanut oil at postpollination attracted more sap beetle adults in 2006, and more sap beetle larvae in 2007. Olive and neem oils significantly reduced husk coverage compared with the water control in both years. The mineral oil application consistently increased smut infection rate in both 2006 and 2007. Ramifications of using oil treatments in ear pest management also are discussed.

Effects of Carriers, Emulsifiers, and Biopesticides for Direct Silk Treatments on Caterpillar Feeding Damage and Ear Development in Sweet Corn.

PubMed

Westgate, P J; Schultz, B B; Hazzard, R V

2017-04-01

In the northeastern United States, control of Lepidopteran pests of sweet corn, particularly corn earworm [Helicoverpa zea (Boddie)], is difficult using organic methods. The direct application of corn oil and Bacillus thuringiensis (Bt) to corn silk has been shown to reduce ear damage from corn earworm in past studies; these studies sought to optimize this method by evaluating additional carrier and biopesticide mixtures that comply with the United States Federal Insecticide, Fungicide, and Rodenticide Act and National Organic Standards. Carriers, which are liquids used to dissolve the biopesticide and deliver it into the tip of the ear, may have phytotoxic or insecticidal properties. Experiments conducted from 2001 to 2005 evaluated caterpillar damage and ear development effects from carriers (vegetable and paraffinic oils and carrageenan), biopesticides (Bt, spinsosad, and neem), and three emulsifiers in various combinations when applied directly to the tips of the ears 5-7 d after silk initiation. There were no effects of emulsifiers on ear quality, except for slight reduction in caterpillar damage in one of the two years. There were no differences among corn, soy, canola, and safflower oils in corn earworm control or tip development. The carrageenan carrier had the least effect upon ear development as measured by the length of nonpollinated kernels at the tip, compared to corn oil or paraffinic oil (JMS Stylet Oil), which caused the greatest tip damage as well as an oily discoloration. The carrier-pesticide combinations with the best ear quality overall were spinosad in carrageenan or corn oil, and Bt in carrageenan. © 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.

Intraguild competition and enhanced survival of western bean cutworm (Lepidoptera: Noctuidae) on transgenic Cry1Ab (MON810) Bacillus thuringiensis corn.

PubMed

Dorhout, David L; Rice, Marlin E

2010-02-01

The effect of genetically modified corn (event MON810, YieldGard Corn Borer) expressing the Bacillus thuringiensis sp. kurstaki (Berliner) (Bt) endotoxin, Cry1Ab, on the survival of western bean cutworm, Striacosta albicosta (Smith), larvae was examined during intraguild competition studies with either European corn borer, Ostrinia nubilalis (Hübner), or corn earworm, Helicoverpa zea (Boddie), larvae. Competition scenarios were constructed by using either a laboratory or field competition arena containing one of five different diets and one of 13 different larval size-by-species scenarios. The survival of western bean cutworms competing with corn earworms in the laboratory arenas on either a meridic diet or isoline corn silk diet was significantly lower (P < or = 0.01) than the controls in 13 out of 14 competition scenarios and larval survival was frequently zero. In contrast, the survival of western bean cutworm competing with corn earworm on a Cry1Ab-MON810 corn silk diet was significant higher (P < or = 0.01) than the controls in four out of six competition scenarios. The results observed in the three way competitions involving the addition of European corn borers generally did not alter the outcomes observed in the western bean cutworm and corn earworm only two-way competitions. These data suggest that Cry1Ab-MON810 corn may confer a competitive advantage to western bean cutworm larvae during intraguild competition, particularly from corn earworms, and that western bean cutworms become equal competitors only when they are of equal or larger size and the diet is Cry1Ab-MON810 corn.

Efficacy of Silk Channel Injections with Insecticides for Management of Lepidoptera Pests of Sweet Corn.

PubMed

Sparks, A N; Gadal, L; Ni, X

2015-08-01

The primary Lepidoptera pests of sweet corn (Zea mays L. convar. saccharata) in Georgia are the corn earworm, Helicoverpa zea (Boddie), and the fall armyworm, Spodoptera frugiperda (J. E. Smith). Management of these pests typically requires multiple insecticide applications from first silking until harvest, with commercial growers frequently spraying daily. This level of insecticide use presents problems for small growers, particularly for "pick-your-own" operations. Injection of oil into the corn ear silk channel 5-8 days after silking initiation has been used to suppress damage by these insects. Initial work with this technique in Georgia provided poor results. Subsequently, a series of experiments was conducted to evaluate the efficacy of silk channel injections as an application methodology for insecticides. A single application of synthetic insecticide, at greatly reduced per acre rates compared with common foliar applications, provided excellent control of Lepidoptera insects attacking the ear tip and suppressed damage by sap beetles (Nitidulidae). While this methodology is labor-intensive, it requires a single application of insecticide at reduced rates applied ∼2 wk prior to harvest, compared with potential daily applications at full rates up to the day of harvest with foliar insecticide applications. This methodology is not likely to eliminate the need for foliar applications because of other insect pests which do not enter through the silk channel or are not affected by the specific selective insecticide used in the silk channel injection, but would greatly reduce the number of applications required. This methodology may prove particularly useful for small acreage growers. © 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.

Field screening of experimental corn hybrids and inbred lines for multiple ear-feeding insect resistance.

PubMed

Ni, Xinzhi; Xu, Wenwei; Krakowsky, Matthew D; Buntin, G David; Brown, Steve L; Lee, R Dewey; Coy, Anton E

2007-10-01

Identifying and using native insect resistance genes is the core of integrated pest management. In this study, 10 experimental corn, Zea mays L., hybrids and 10 inbred lines were screened for resistance to major ear-feeding insects in the southeastern Coastal Plain region of the United States during 2004 and 2005. Ear-feeding insect damage was assessed at harvest by visual damage rating for the corn earworm, Helicoverpa zea (Boddie), and by the percentage of kernels damaged by the maize weevil, Sitophilus zeamais Motschulsky, and stink bugs [combination of Euschistus servus (Say) and southern green stink bug, Nezara viridula (L.)]. Among the eight inbred lines and two control populations examined, C3S1B73-5b was resistant to corn earworm, maize weevil, and stink bugs. In contrast, C3S1B73-4 was resistant to corn earworm and stink bugs, but not to maize weevil. In a similar manner, the corn hybrid S1W*CML343 was resistant to all three ear-feeding insects, whereas hybrid C3S1B73-3*Tx205 was resistant to corn earworm and maize weevil in both growing seasons, but susceptible to stink bugs in 2005. The silk-feeding bioassay showed that corn earworm developed better on corn silk than did fall armyworm. Among all phenotypic traits examined (i.e., corn ear size, husk extension, and husk tightness), only corn ear size was negatively correlated to corn earworm damage in the inbred lines examined, whereas only husk extension (i.e., coverage) was negatively correlated to both corn earworm and maize weevil damage on the experimental hybrids examined. Such information could be used to establish a baseline for developing agronomically elite corn germplasm that confers multiple ear-feeding insect resistance.

Genomic and functional characterization of coleopteran insect-specific α-amylase inhibitor gene from Amaranthus species.

PubMed

Bhide, Amey J; Channale, Sonal M; Yadav, Yashpal; Bhattacharjee, Kabita; Pawar, Pankaj K; Maheshwari, V L; Gupta, Vidya S; Ramasamy, Sureshkumar; Giri, Ashok P

2017-06-01

The smallest 32 amino acid α-amylase inhibitor from Amaranthus hypochondriacus (AAI) is reported. The complete gene of pre-protein (AhAI) encoding a 26 amino acid (aa) signal peptide followed by the 43 aa region and the previously identified 32 aa peptide was cloned successfully. Three cysteine residues and one disulfide bond conserved within known α-amylase inhibitors were present in AhAI. Identical genomic and open reading frame was found to be present in close relatives of A. hypochondriacus namely Amaranthus paniculatus, Achyranthes aspera and Celosia argentea. Interestingly, the 3'UTR of AhAI varied in these species. The highest expression of AhAI was observed in A. hypochondriacus inflorescence; however, it was not detected in the seed. We hypothesized that the inhibitor expressed in leaves and inflorescence might be transported to the seeds. Sub-cellular localization studies clearly indicated the involvement of AhAI signal peptide in extracellular secretion. Full length rAhAI showed differential inhibition against α-amylases from human, insects, fungi and bacteria. Particularly, α-amylases from Helicoverpa armigera (Lepidoptera) were not inhibited by AhAI while Tribolium castaneum and Callosobruchus chinensis (Coleoptera) α-amylases were completely inhibited. Molecular docking of AhAI revealed tighter interactions with active site residues of T. castaneum α-amylase compared to C. chinensis α-amylase, which could be the rationale behind the disparity in their IC 50 . Normal growth, development and adult emergence of C. chinensis were hampered after feeding on rAhAI. Altogether, the ability of AhAI to affect the growth of C. chinensis demonstrated its potential as an efficient bio-control agent, especially against stored grain pests.

Molecular Docking and Site-directed Mutagenesis of a Bacillus thuringiensis Chitinase to Improve Chitinolytic, Synergistic Lepidopteran-larvicidal and Nematicidal Activities

PubMed Central

Ni, Hong; Zeng, Siquan; Qin, Xu; Sun, Xiaowen; Zhang, Shan; Zhao, Xiuyun; Yu, Ziniu; Li, Lin

2015-01-01

Bacterial chitinases are useful in the biocontrol of agriculturally important pests and fungal pathogens. However, the utility of naturally occurring bacterial chitinases is often limited by their low enzyme activity. In this study, we constructed mutants of a Bacillus thuringiensis chitinase with enhanced activity based on homology modeling, molecular docking, and the site-directed mutagenesis of target residues to modify spatial positions, steric hindrances, or hydrophilicity/hydrophobicity. We first identified a gene from B. thuringiensis YBT-9602 that encodes a chitinase (Chi9602) belonging to glycosyl hydrolase family 18 with conserved substrate-binding and substrate-catalytic motifs. We constructed a structural model of a truncated version of Chi9602 (Chi960235-459) containing the substrate-binding domain using the homologous 1ITX protein of Bacillus circulans as the template. We performed molecular docking analysis of Chi960235-459 using di-N-acetyl-D-glucosamine as the ligand. We then selected 10 residues of interest from the docking area for the site-directed mutagenesis experiments and expression in Escherichia coli. Assays of the chitinolytic activity of the purified chitinases revealed that the three mutants exhibited increased chitinolytic activity. The ChiW50A mutant exhibited a greater than 60 % increase in chitinolytic activity, with similar pH, temperature and metal ion requirements, compared to wild-type Chi9602. Furthermore, ChiW50A exhibited pest-controlling activity and antifungal activity. Remarkable synergistic effects of this mutant with B. thuringiensis spore-crystal preparations against Helicoverpa armigera and Caenorhabditis elegans larvae and obvious activity against several plant-pathogenic fungi were observed. PMID:25678849

Role of Tomato Lipoxygenase D in Wound-Induced Jasmonate Biosynthesis and Plant Immunity to Insect Herbivores

PubMed Central

Li, Shuyu; Wang, Bao; Huang, Tingting; Du, Minmin; Sun, Jiaqiang; Kang, Le; Li, Chang-Bao; Li, Chuanyou

2013-01-01

In response to insect attack and mechanical wounding, plants activate the expression of genes involved in various defense-related processes. A fascinating feature of these inducible defenses is their occurrence both locally at the wounding site and systemically in undamaged leaves throughout the plant. Wound-inducible proteinase inhibitors (PIs) in tomato (Solanum lycopersicum) provide an attractive model to understand the signal transduction events leading from localized injury to the systemic expression of defense-related genes. Among the identified intercellular molecules in regulating systemic wound response of tomato are the peptide signal systemin and the oxylipin signal jasmonic acid (JA). The systemin/JA signaling pathway provides a unique opportunity to investigate, in a single experimental system, the mechanism by which peptide and oxylipin signals interact to coordinate plant systemic immunity. Here we describe the characterization of the tomato suppressor of prosystemin-mediated responses8 (spr8) mutant, which was isolated as a suppressor of (pro)systemin-mediated signaling. spr8 plants exhibit a series of JA-dependent immune deficiencies, including the inability to express wound-responsive genes, abnormal development of glandular trichomes, and severely compromised resistance to cotton bollworm (Helicoverpa armigera) and Botrytis cinerea. Map-based cloning studies demonstrate that the spr8 mutant phenotype results from a point mutation in the catalytic domain of TomLoxD, a chloroplast-localized lipoxygenase involved in JA biosynthesis. We present evidence that overexpression of TomLoxD leads to elevated wound-induced JA biosynthesis, increased expression of wound-responsive genes and, therefore, enhanced resistance to insect herbivory attack and necrotrophic pathogen infection. These results indicate that TomLoxD is involved in wound-induced JA biosynthesis and highlight the application potential of this gene for crop protection against insects and pathogens. PMID:24348260

Effects of Interplanting Flowering Plants on the Biological Control of Corn Earworm (Lepidoptera: Noctuidae) and Thrips (Thysanoptera: Thripidae) in Sweet Corn.

PubMed

Manandhar, Roshan; Wright, Mark G

2016-02-01

Natural enemy exploitation of food resources and alternative hosts in noncrop vegetation has been shown to be an effective means of enhancing natural enemy populations in diversified agro-ecosystem. Field trials were conducted in Hawaii to examine effects of interplanting flowering plants on 1) parasitism of corn earworm, Helicoverpa zea (Boddie) eggs by Trichogramma spp., and 2) abundance of Orius spp. in relation to prey (H. zea eggs and thrips [primarily, Frankliniella occidentalis (Pergande) and Frankliniella williamsi Hood]). Sweet corn (maize), Zea mays L., was interplanted with three flowering plants, buckwheat, Fagopyrum esculentum Moench, cowpea, Vigna unguiculata (L.), and sunn hemp, Crotolaria juncea L., at 2:1 and 4:1 (corn: flowering plant) ratios in 2009 and 2010, respectively. In 2009, the abundance of Orius spp. was significantly greater in the buckwheat-interplanted treatment compared to the monocrop control at similar levels of prey availability, indicating buckwheat flowers might have provided both prey and nectar resources. In 2010, cowpea and sunn hemp flowering plants provided a source of an alternate host insect's eggs for Trichogramma spp. oviposition, resulting in significantly higher parasitism of H. zea eggs in the cowpea- and sunn hemp-interplanted treatments compared to the monocrop control. Despite of differences in pest and natural enemy interactions in two field trials, our findings suggested that provisioning of an alternate host insect's eggs through flowering plants is an effective means for enhancing Trichogramma spp. and provisioning of both nectar and prey resources through flowering plants is important for enhancing predation by Orius spp. © 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.

Role of tomato lipoxygenase D in wound-induced jasmonate biosynthesis and plant immunity to insect herbivores.

PubMed

Yan, Liuhua; Zhai, Qingzhe; Wei, Jianing; Li, Shuyu; Wang, Bao; Huang, Tingting; Du, Minmin; Sun, Jiaqiang; Kang, Le; Li, Chang-Bao; Li, Chuanyou

2013-01-01

In response to insect attack and mechanical wounding, plants activate the expression of genes involved in various defense-related processes. A fascinating feature of these inducible defenses is their occurrence both locally at the wounding site and systemically in undamaged leaves throughout the plant. Wound-inducible proteinase inhibitors (PIs) in tomato (Solanum lycopersicum) provide an attractive model to understand the signal transduction events leading from localized injury to the systemic expression of defense-related genes. Among the identified intercellular molecules in regulating systemic wound response of tomato are the peptide signal systemin and the oxylipin signal jasmonic acid (JA). The systemin/JA signaling pathway provides a unique opportunity to investigate, in a single experimental system, the mechanism by which peptide and oxylipin signals interact to coordinate plant systemic immunity. Here we describe the characterization of the tomato suppressor of prosystemin-mediated responses8 (spr8) mutant, which was isolated as a suppressor of (pro)systemin-mediated signaling. spr8 plants exhibit a series of JA-dependent immune deficiencies, including the inability to express wound-responsive genes, abnormal development of glandular trichomes, and severely compromised resistance to cotton bollworm (Helicoverpa armigera) and Botrytis cinerea. Map-based cloning studies demonstrate that the spr8 mutant phenotype results from a point mutation in the catalytic domain of TomLoxD, a chloroplast-localized lipoxygenase involved in JA biosynthesis. We present evidence that overexpression of TomLoxD leads to elevated wound-induced JA biosynthesis, increased expression of wound-responsive genes and, therefore, enhanced resistance to insect herbivory attack and necrotrophic pathogen infection. These results indicate that TomLoxD is involved in wound-induced JA biosynthesis and highlight the application potential of this gene for crop protection against insects and pathogens.

Potential shortfall of pyramided transgenic cotton for insect resistance management

PubMed Central

Brévault, Thierry; Heuberger, Shannon; Zhang, Min; Ellers-Kirk, Christa; Ni, Xinzhi; Masson, Luke; Li, Xianchiun; Tabashnik, Bruce E.; Carrière, Yves

2013-01-01

To delay evolution of pest resistance to transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt), the “pyramid” strategy uses plants that produce two or more toxins that kill the same pest. In the United States, this strategy has been adopted widely, with two-toxin Bt cotton replacing one-toxin Bt cotton. Although two-toxin plants are likely to be more durable than one-toxin plants, the extent of this advantage depends on several conditions. One key assumption favoring success of two-toxin plants is that they kill insects selected for resistance to one toxin, which is called “redundant killing.” Here we tested this assumption for a major pest, Helicoverpa zea, on transgenic cotton producing Bt toxins Cry1Ac and Cry2Ab. Selection with Cry1Ac increased survival on two-toxin cotton, which contradicts the assumption. The concentration of Cry1Ac and Cry2Ab declined during the growing season, which would tend to exacerbate this problem. Furthermore, analysis of results from 21 selection experiments with eight species of lepidopteran pests indicates that some cross-resistance typically occurs between Cry1A and Cry2A toxins. Incorporation of empirical data into simulation models shows that the observed deviations from ideal conditions could greatly reduce the benefits of the pyramid strategy for pests like H. zea, which have inherently low susceptibility to Bt toxins and have been exposed extensively to one of the toxins in the pyramid before two-toxin plants are adopted. For such pests, the pyramid strategy could be improved by incorporating empirical data on deviations from ideal assumptions about redundant killing and cross-resistance. PMID:23530245

Next-generation transgenic cotton: pyramiding RNAi and Bt counters insect resistance.

PubMed

Ni, Mi; Ma, Wei; Wang, Xiaofang; Gao, Meijing; Dai, Yan; Wei, Xiaoli; Zhang, Lei; Peng, Yonggang; Chen, Shuyuan; Ding, Lingyun; Tian, Yue; Li, Jie; Wang, Haiping; Wang, Xiaolin; Xu, Guowang; Guo, Wangzhen; Yang, Yihua; Wu, Yidong; Heuberger, Shannon; Tabashnik, Bruce E; Zhang, Tianzhen; Zhu, Zhen

2017-09-01

Transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are extensively cultivated worldwide. To counter rapidly increasing pest resistance to crops that produce single Bt toxins, transgenic plant 'pyramids' producing two or more Bt toxins that kill the same pest have been widely adopted. However, cross-resistance and antagonism between Bt toxins limit the sustainability of this approach. Here we describe development and testing of the first pyramids of cotton combining protection from a Bt toxin and RNA interference (RNAi). We developed two types of transgenic cotton plants producing double-stranded RNA (dsRNA) from the global lepidopteran pest Helicoverpa armigera designed to interfere with its metabolism of juvenile hormone (JH). We focused on suppression of JH acid methyltransferase (JHAMT), which is crucial for JH synthesis, and JH-binding protein (JHBP), which transports JH to organs. In 2015 and 2016, we tested larvae from a Bt-resistant strain and a related susceptible strain of H. armigera on seven types of cotton: two controls, Bt cotton, two types of RNAi cotton (targeting JHAMT or JHBP) and two pyramids (Bt cotton plus each type of RNAi). Both types of RNAi cotton were effective against Bt-resistant insects. Bt cotton and RNAi acted independently against the susceptible strain. In computer simulations of conditions in northern China, where millions of farmers grow Bt cotton as well as abundant non-transgenic host plants of H. armigera, pyramided cotton combining a Bt toxin and RNAi substantially delayed resistance relative to using Bt cotton alone. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Combination of endophytic Bacillus and Beauveria for the management of Fusarium wilt and fruit borer in tomato.

PubMed

Prabhukarthikeyan, Rathinam; Saravanakumar, Duraisamy; Raguchander, Thiruvengadam

2014-11-01

Most of the approaches for biocontrol of pests and diseases have used a single biocontrol agent as antagonist to a single pest or pathogen. This accounts for the inconsistency in the performance of biocontrol agents. The development of a bioformulation possessing a mixture of bioagents could be a viable option for the management of major pests and diseases in crop plants. A bioformulation containing a mixture of Beauveria bassiana (B2) and Bacillus subtilis (EPC8) was tested against Fusarium wilt and fruit borer in tomato under glasshouse and field conditions. The bioformulation with B2 and EPC8 isolates effectively reduced the incidence of Fusarium wilt (Fusarium oxysporum f. sp. lycopersici) and fruit borer (Helicoverpa armigera) under glasshouse and field conditions compared with the individual application of B2 and EPC8 isolates and control treatments. In vitro studies showed a higher larval mortality of H. armigera when fed with B2 + EPC8-treated leaves. Further, plants treated with the B2 + EPC8 combination showed a greater accumulation of defence enzymes such as lipoxygenase, peroxidase and polyphenol oxidase against wilt pathogen and fruit borer pest than the other treatments. Moreover, a significant increase in growth parameters and yield was observed in tomato plants treated with B2 + EPC8 compared with the individual bioformulations and untreated control. The combined application of Beauveria and Bacillus isolates B2 and EPC8 effectively reduced wilt disease and fruit borer attack in tomato plants. Results show the possibility of synchronous management of tomato fruit borer pest and wilt disease in a sustainable manner. © 2013 Society of Chemical Industry.

Associations of planting date, drought stress, and insects with Fusarium ear rot and fumonisin B1 contamination in California maize.

PubMed

Parsons, M W; Munkvold, G P

2010-05-01

Fusarium ear rot, caused by Fusarium verticillioides, is one of the most common diseases of maize, causing yield and quality reductions and contamination of grain by fumonisins and other mycotoxins. Drought stress and various insects have been implicated as factors affecting disease severity. Field studies were conducted to evaluate the interactions and relative influences of drought stress, insect infestation, and planting date upon Fusarium ear rot severity and fumonisin B1 contamination. Three hybrids varying in partial resistance to Fusarium ear rot were sown on three planting dates and subjected to four irrigation regimes to induce differing levels of drought stress. A foliar-spray insecticide treatment was imposed to induce differing levels of insect injury. Populations of thrips (Frankliniella spp.), damage by corn earworm (Helicoverpa zeae), Fusarium ear rot symptoms, and fumonisin B1 levels were assessed. There were significant effects of hybrid, planting date, insecticide treatment, and drought stress on Fusarium ear rot symptoms and fumonisin B1 contamination, and these factors also had significant interacting effects. The most influential factors were hybrid and insecticide treatment, but their effects were influenced by planting date and drought stress. The more resistant hybrids and the insecticide-treated plots consistently had lower Fusarium ear rot severity and fumonisin B1 contamination. Later planting dates typically had higher thrips populations, more Fusarium ear rot, and higher levels of fumonisin B1. Insect activity was significantly correlated with disease severity and fumonisin contamination, and the correlations were strongest for thrips. The results of this study confirm the influence of thrips on Fusarium ear rot severity in California, USA, and also establish a strong association between thrips and fumonisin B1 levels.

Persistence, metabolism and safety evaluation of thiamethoxam in tomato crop.

PubMed

Karmakar, Rajib; Kulshrestha, Gita

2009-08-01

Thiamethoxam, a neonicotinoid insecticide, has been widely accepted for use in various crops, including vegetables, owing to its high efficacy against various chewing and sucking insect pests. In this particular study, the authors examined the residue dynamics of this insecticide in tomato and soil and calculated a safety index for this insecticide in an Indian context. In tomato fruits, the insecticide dissipated from 82 to 87% in 10 days with a half-life of 4 days, whereas dissipation in soil, under tomato crop, varied between 72 and 75% in 15 days with a half-life of 9 days. Total residues reached below detectable level in 15 days in tomato fruits and 20 days in soil. Maximum damage (30%) was found in control plots, as opposed to 8-10% of fruit damage in treated plots. One degradation product was detected on the tomato fruit surface, and three metabolites were identified in tomato fruits by the LC-MS technique. The metabolites have been reported for the first time in tomato fruits. Thiamethoxam at normal and double the recommended use rate effectively controlled aphids, whiteflies and Helicoverpa, as the insect population decreased to a minimum within 10 days of spraying in comparison with the control. There was no significant difference between the two rates of application, and both thiamethoxam treatments significantly increased tomato fruit yield compared with the untreated control. A maximum residue limit (MRL) of 0.05 mg kg(-1) for tomato has been proposed, with a corresponding preharvest interval (PHI) of 8 days. These parallel advances in toxicology and analytical chemistry have strengthened the observations that thiamethoxam can be used safely and efficiently in crop protection programmes.

Tolerance and resistance of invasive and native Eupatorium species to generalist herbivore insects

NASA Astrophysics Data System (ADS)

Wang, Rui-Fang; Feng, Yu-Long

2016-11-01

Invasive plants are exotic species that escape control by native specialist enemies. However, exotic plants may still be attacked by locally occurring generalist enemies, which can influence the dynamics of biological invasions. If invasive plants have greater defensive (resistance and tolerance) capabilities than indigenous plants, they may experience less damage from native herbivores. In the present study, we tested this prediction using the invasive plant Eupatorium adenophorum and two native congeners under simulated defoliation and generalist herbivore insect (Helicoverpa armigera and Spodoptera litura) treatments. E. adenophorum was less susceptible and compensated more quickly to damages in biomass production from both treatments compared to its two congeners, exhibiting greater herbivore tolerance. This strong tolerance to damage was associated with greater resource allocation to aboveground structures, leading to a higher leaf area ratio and a lower root: crown mass ratio than those of its native congeners. E. adenophorum also displayed a higher resistance index (which integrates acid detergent fiber, nitrogen content, carbon/nitrogen ratio, leaf mass per area, toughness, and trichome density) than its two congeners. Thus, H. armigera and S. litura performed poorly on E. adenophorum, with less leaf damage, a lengthened insect developmental duration, and decreased pupating: molting ratios compared to those of the native congeners. Strong tolerance and resistance traits may facilitate the successful invasion of E. adenophorum in China and may decrease the efficacy of leaf-feeding biocontrol agents. Our results highlight both the need for further research on defensive traits and their role in the invasiveness and biological control of exotic plants, and suggest that biocontrol of E. adenophorum in China would require damage to the plant far in excess of current levels.

Transgenic cotton coexpressing Vip3A and Cry1Ac has a broad insecticidal spectrum against lepidopteran pests.

PubMed

Chen, Wen-Bo; Lu, Guo-Qing; Cheng, Hong-Mei; Liu, Chen-Xi; Xiao, Yu-Tao; Xu, Chao; Shen, Zhi-Cheng; Wu, Kong-Ming

2017-10-01

Although farmers in China have grown transgenic Bt-Cry1Ac cotton to resist the major pest Helicoverpa armigera since 1997 with great success, many secondary lepidopteran pests that are tolerant to Cry1Ac are now reported to cause considerable economic damage. Vip3AcAa, a chimeric protein with the N-terminal part of Vip3Ac and the C-terminal part of Vip3Aa, has a broad insecticidal spectrum against lepidopteran pests and has no cross resistance to Cry1Ac. In the present study, we tested insecticidal activities of Vip3AcAa against Spodoptera litura, Spodoptera exigua, and Agrotis ipsilon, which are relatively tolerant to Cry1Ac proteins. The bioassay results showed that insecticidal activities of Vip3AcAa against these three pests are superior to Cry1Ac, and after an activation pretreatment, Vip3AcAa retained insecticidal activity against S. litura, S. exigua and A. ipsilon that was similar to the unprocessed protein. The putative receptor for this chimeric protein in the brush border membrane vesicle (BBMV) in the three pests was also identified using biotinylated Vip3AcAa toxin. To broaden Bt cotton activity against a wider spectrum of pests, we introduced the vip3AcAa and cry1Ac genes into cotton. Larval mortality rates for S. litura, A. ipsilon and S. exigua that had fed on this new cotton increased significantly compared with larvae fed on non-Bt cotton and Bt-Cry1Ac cotton in a laboratory experiment. These results suggested that the Vip3AcAa protein is an excellent option for a "pyramid" strategy for integrated pest management in China. Copyright © 2017 Elsevier Inc. All rights reserved.

Isolation of an Orally Active Insecticidal Toxin from the Venom of an Australian Tarantula

PubMed Central

Hardy, Margaret C.; Daly, Norelle L.; Mobli, Mehdi; Morales, Rodrigo A. V.; King, Glenn F.

2013-01-01

Many insect pests have developed resistance to existing chemical insecticides and consequently there is much interest in the development of new insecticidal compounds with novel modes of action. Although spiders have deployed insecticidal toxins in their venoms for over 250 million years, there is no evolutionary selection pressure on these toxins to possess oral activity since they are injected into prey and predators via a hypodermic needle-like fang. Thus, it has been assumed that spider-venom peptides are not orally active and are therefore unlikely to be useful insecticides. Contrary to this dogma, we show that it is possible to isolate spider-venom peptides with high levels of oral insecticidal activity by directly screening for per os toxicity. Using this approach, we isolated a 34-residue orally active insecticidal peptide (OAIP-1) from venom of the Australian tarantula Selenotypus plumipes. The oral LD50 for OAIP-1 in the agronomically important cotton bollworm Helicoverpa armigera was 104.2±0.6 pmol/g, which is the highest per os activity reported to date for an insecticidal venom peptide. OAIP-1 is equipotent with synthetic pyrethroids and it acts synergistically with neonicotinoid insecticides. The three-dimensional structure of OAIP-1 determined using NMR spectroscopy revealed that the three disulfide bonds form an inhibitor cystine knot motif; this structural motif provides the peptide with a high level of biological stability that probably contributes to its oral activity. OAIP-1 is likely to be synergized by the gut-lytic activity of the Bacillus thuringiensis Cry toxin (Bt) expressed in insect-resistant transgenic crops, and consequently it might be a good candidate for trait stacking with Bt. PMID:24039872

Metabolic engineering of monoterpene biosynthesis in tomato fruits via introduction of the non-canonical substrate neryl diphosphate.

PubMed

Gutensohn, Michael; Nguyen, Thuong T H; McMahon, Richard D; Kaplan, Ian; Pichersky, Eran; Dudareva, Natalia

2014-07-01

Recently it was shown that monoterpenes in tomato trichomes (Solanum lycopersicum) are synthesized by phellandrene synthase 1 (PHS1) from the non-canonical substrate neryl diphosphate (NPP), the cis-isomer of geranyl diphosphate (GPP). As PHS1 accepts both NPP and GPP substrates forming different monoterpenes, it was overexpressed in tomato fruits to test if NPP is also available in a tissue highly active in carotenoid production. However, transgenic fruits overexpressing PHS1 produced only small amounts of GPP-derived PHS1 monoterpene products, indicating the absence of endogenous NPP. Therefore, NPP formation was achieved by diverting the metabolic flux from carotenoids via expression of tomato neryl diphosphate synthase 1 (NDPS1). NDPS1 transgenic fruits produced NPP-derived monoterpenes, including nerol, neral and geranial, while displaying reduced lycopene content. NDPS1 co-expression with PHS1 resulted in a monoterpene blend, including β-phellandrene, similar to that produced from NPP by PHS1 in vitro and in trichomes. Unexpectedly, PHS1×NDPS1 fruits showed recovery of lycopene levels compared to NDPS1 fruits, suggesting that redirection of metabolic flux is only partially responsible for the reduction in carotenoids. In vitro assays demonstrated that NPP serves as an inhibitor of geranylgeranyl diphosphate synthase, thus its consumption by PHS1 leads to recovery of lycopene levels. Monoterpenes produced in PHS1×NDPS1 fruits contributed to direct plant defense negatively affecting feeding behavior of the herbivore Helicoverpa zea and displaying antifungal activity against Botrytis cinerea. These results show that NPP-derived terpenoids can be produced in plant tissues; however, NPP has to be consumed to avoid negative impacts on plant metabolism. Copyright © 2014 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

How Predictable Are the Behavioral Responses of Insects to Herbivore Induced Changes in Plants? Responses of Two Congeneric Thrips to Induced Cotton Plants

PubMed Central

Silva, Rehan; Furlong, Michael J.; Wilson, Lewis J.; Walter, Gimme H.

2013-01-01

Changes in plants following insect attack are referred to as induced responses. These responses are widely viewed as a form of defence against further insect attack. In the current study we explore whether it is possible to make generalizations about induced plant responses given the unpredictability and variability observed in insect-plant interactions. Experiments were conducted to test for consistency in the responses of two congeneric thrips, Frankliniella schultzei Trybom and Frankliniella occidentalis Pergrande (Thysanoptera: Thripidae) to cotton seedlings (Gossypium hirsutum Linneaus (Malvales: Malvaceae)) damaged by various insect herbivores. In dual-choice experiments that compared intact and damaged cotton seedlings, F. schultzei was attracted to seedlings damaged by Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), Tetranychus urticae (Koch) (Trombidiforms: Tetranychidae), Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae), F. schultzei and F. occidentalis but not to mechanically damaged seedlings. In similar tests, F. occidentalis was attracted to undamaged cotton seedlings when simultaneously exposed to seedlings damaged by H. armigera, T. molitor or F. occidentalis. However, when exposed to F. schultzei or T. urticae damaged plants, F. occidentalis was more attracted towards damaged plants. A quantitative relationship was also apparent, F. schultzei showed increased attraction to damaged seedlings as the density of T. urticae or F. schultzei increased. In contrast, although F. occidentalis demonstrated increased attraction to plants damaged by higher densities of T. urticae, there was a negative relationship between attraction and the density of damaging conspecifics. Both species showed greater attraction to T. urticae damaged seedlings than to seedlings damaged by conspecifics. Results demonstrate that the responses of both species of thrips were context dependent, making generalizations difficult to formulate. PMID:23691075

A 2-Year Field Study Shows Little Evidence That the Long-Term Planting of Transgenic Insect-Resistant Cotton Affects the Community Structure of Soil Nematodes

PubMed Central

Li, Xiaogang; Liu, Biao

2013-01-01

Transgenic insect-resistant cotton has been released into the environment for more than a decade in China to effectively control the cotton bollworm (Helicoverpa armigera) and other Lepidoptera. Because of concerns about undesirable ecological side-effects of transgenic crops, it is important to monitor the potential environmental impact of transgenic insect-resistant cotton after commercial release. Our 2-year study included 1 cotton field where non-transgenic cotton had been planted continuously and 2 other cotton fields where transgenic insect-resistant cotton had been planted for different lengths of time since 1997 and since 2002. In 2 consecutive years (2009 and 2010), we took soil samples from 3 cotton fields at 4 different growth stages (seedling, budding, boll-forming and boll-opening stages), collected soil nematodes from soil with the sugar flotation and centrifugation method and identified the soil nematodes to the genus level. The generic composition, individual densities and diversity indices of the soil nematodes did not differ significantly between the 2 transgenic cotton fields and the non-transgenic cotton field, but significant seasonal variation was found in the individual densities of the principal trophic groups and in the diversity indices of the nematodes in all 3 cotton fields. The study used a comparative perspective to monitor the impact of transgenic insect-resistant cotton grown in typical ‘real world’ conditions. The results of the study suggested that more than 10 years of cultivation of transgenic insect-resistant cotton had no significant effects–adverse or otherwise–on soil nematodes. This study provides a theoretical basis for ongoing environmental impact monitoring of transgenic plants. PMID:23613899

Spatio-Temporal Variation in Landscape Composition May Speed Resistance Evolution of Pests to Bt Crops.

PubMed

Ives, Anthony R; Paull, Cate; Hulthen, Andrew; Downes, Sharon; Andow, David A; Haygood, Ralph; Zalucki, Myron P; Schellhorn, Nancy A

2017-01-01

Transgenic crops that express insecticide genes from Bacillus thuringiensis (Bt) are used worldwide against moth and beetle pests. Because these engineered plants can kill over 95% of susceptible larvae, they can rapidly select for resistance. Here, we use a model for a pyramid two-toxin Bt crop to explore the consequences of spatio-temporal variation in the area of Bt crop and non-Bt refuge habitat. We show that variability over time in the proportion of suitable non-Bt breeding habitat, Q, or in the total area of Bt and suitable non-Bt habitat, K, can increase the overall rate of resistance evolution by causing short-term surges of intense selection. These surges can be exacerbated when temporal variation in Q and/or K cause high larval densities in refuges that increase density-dependent mortality; this will give resistant larvae in Bt fields a relative advantage over susceptible larvae that largely depend on refuges. We address the effects of spatio-temporal variation in a management setting for two bollworm pests of cotton, Helicoverpa armigera and H. punctigera, and field data on landscape crop distributions from Australia. Even a small proportion of Bt fields available to egg-laying females when refuges are sparse may result in high exposure to Bt for just a single generation per year and cause a surge in selection. Therefore, rapid resistance evolution can occur when Bt crops are rare rather than common in the landscape. These results highlight the need to understand spatio-temporal fluctuations in the landscape composition of Bt crops and non-Bt habitats in order to design effective resistance management strategies.

High Expression of Cry1Ac Protein in Cotton (Gossypium hirsutum) by Combining Independent Transgenic Events that Target the Protein to Cytoplasm and Plastids.

PubMed

Singh, Amarjeet Kumar; Paritosh, Kumar; Kant, Uma; Burma, Pradeep Kumar; Pental, Deepak

2016-01-01

Transgenic cotton was developed using two constructs containing a truncated and codon-modified cry1Ac gene (1,848 bp), which was originally characterized from Bacillus thuringiensis subspecies kurstaki strain HD73 that encodes a toxin highly effective against many lepidopteran pests. In Construct I, the cry1Ac gene was cloned under FMVde, a strong constitutively expressing promoter, to express the encoded protein in the cytoplasm. In Construct II, the encoded protein was directed to the plastids using a transit peptide taken from the cotton rbcSIb gene. Genetic transformation experiments with Construct I resulted in a single copy insertion event in which the Cry1Ac protein expression level was 2-2.5 times greater than in the Bacillus thuringiensis cotton event Mon 531, which is currently used in varieties and hybrids grown extensively in India and elsewhere. Another high expression event was selected from transgenics developed with Construct II. The Cry protein expression resulting from this event was observed only in the green plant parts. No transgenic protein expression was observed in the non-green parts, including roots, seeds and non-green floral tissues. Thus, leucoplasts may lack the mechanism to allow entry of a protein tagged with the transit peptide from a protein that is only synthesized in tissues containing mature plastids. Combining the two events through sexual crossing led to near additive levels of the toxin at 4-5 times the level currently used in the field. The two high expression events and their combination will allow for effective resistance management against lepidopteran insect pests, particularly Helicoverpa armigera, using a high dosage strategy.

Quantitative trait loci and metabolic pathways: genetic control of the concentration of maysin, a corn earworm resistance factor, in maize silks.

PubMed Central

Byrne, P F; McMullen, M D; Snook, M E; Musket, T A; Theuri, J M; Widstrom, N W; Wiseman, B R; Coe, E H

1996-01-01

Interpretation of quantitative trait locus (QTL) studies of agronomic traits is limited by lack of knowledge of biochemical pathways leading to trait expression. To more fully elucidate the biological significance of detected QTL, we chose a trait that is the product of a well-characterized pathway, namely the concentration of maysin, a C-glycosyl flavone, in silks of maize, Zea mays L. Maysin is a host-plant resistance factor against the corn earworm, Helicoverpa zea (Boddie). We determined silk maysin concentrations and restriction fragment length polymorphism genotypes at flavonoid pathway loci or linked markers for 285 F2 plants derived from the cross of lines GT114 and GT119. Single-factor analysis of variance indicated that the p1 region on chromosome 1 accounted for 58.0% of the phenotypic variance and showed additive gene action. The p1 locus is a transcription activator for portions of the flavonoid pathway. A second QTL, represented by marker umc 105a near the brown pericarp1 locus on chromosome 9, accounted for 10.8% of the variance. Gene action of this region was dominant for low maysin, but was only expressed in the presence of a functional p1 allele. The model explaining the greatest proportion of phenotypic variance (75.9%) included p1, umc105a, umc166b (chromosome 1), r1 (chromosome 10), and two epistatic interaction terms, p1 x umc105a and p1 x r1. Our results provide evidence that regulatory loci have a central role and that there is a complex interplay among different branches of the flavonoid pathway in the expression of this trait. PMID:11607699

The first report of Xenorhabdus indica from Steinernema pakistanense: co-phylogenetic study suggests co-speciation between X. indica and its steinernematid nematodes.

PubMed

Bhat, A H; Chaubey, A K; Půža, V

2018-01-17

During a survey in agricultural fields of the sub-humid region of Meerut district, India, two strains of entomopathogenic nematodes, labelled CS31 and CS32, were isolated using the Galleria baiting technique. Based on morphological and morphometric studies, and molecular data, the nematodes were identified as Steinernema pakistanense, making this finding the first report of this species from India. For the first time, we performed a molecular and biochemical characterization of the bacterial symbiont of S. pakistanense. Furthermore, a co-phylogenetic analysis of the bacteria from the monophyletic clade containing a symbiont of S. pakistanense, together with their nematode hosts, was conducted, to test the degree of nematode-bacteria co-speciation. Both isolates were also tested in a laboratory assay for pathogenicity against two major pests, Helicoverpa armigera and Spodoptera litura. The morphology of the Indian isolates corresponds mainly to the original description, with the only difference being the absence of a mucron in first-generation females and missing epiptygmata in the second generation. The sequences of bacterial recA and gyrB genes have shown that the symbiont of S. pakistanense is closely related to Xenorhabdus indica, which is associated with some other nematodes from the 'bicornutum' group. Co-phylogenetic analysis has shown a remarkable congruence between the nematode and bacterial phylogenies, suggesting that, in some lineages within the Steinernema / Xenorhabdus complex, the nematodes and bacteria have undergone co-speciation. In the virulence assay, both strains caused a 100% mortality of both tested insects after 48 h, even at the lowest doses of 25 infective juveniles per insect, suggesting that S. pakistanense could be considered for use in the biocontrol of these organisms in India.

Multifaceted effects of host plants on entomopathogenic nematodes.

PubMed

Hazir, Selcuk; Shapiro-Ilan, David I; Hazir, Canan; Leite, Luis G; Cakmak, Ibrahim; Olson, Dawn

2016-03-01

The success of parasites can be impacted by multi-trophic interactions. Tritrophic interactions have been observed in parasite-herbivore-host plant systems. Here we investigate aspects of multi-trophic interactions in a system involving an entomopathogenic nematode (EPN), its insect host, and host plant. Novel issues investigated include the impact of tritrophic interactions on nematode foraging behavior, the ability of EPNs to overcome negative tritrophic effects through genetic selection, and interactions with a fourth trophic level (nematode predators). We tested infectivity of the nematode, Steinernema riobrave, to corn earworm larvae (Helicoverpa zea) in three host plants, tobacco, eggplant and tomato. Tobacco reduced nematode virulence and reproduction relative to tomato and eggplant. However, successive selection (5 passages) overcame the deficiency; selected nematodes no longer exhibited reductions in phenotypic traits. Despite the loss in virulence and reproduction nematodes, first passage S. riobrave was more attracted to frass from insects fed tobacco than insects fed on other host plants. Therefore, we hypothesized the reduced virulence and reproduction in S. riobrave infecting tobacco fed insects would be based on a self-medicating tradeoff, such as deterring predation. We tested this hypothesis by assessing predatory success of the mite Sancassania polyphyllae and the springtail Sinella curviseta on nematodes reared on tobacco-fed larvae versus those fed on greater wax moth, Galleria mellonella, tomato fed larvae, or eggplant fed larvae. No advantage was observed in nematodes derived from tobacco fed larvae. In conclusion, our results indicated that insect-host plant diet has an important effect on nematode foraging, infectivity and reproduction. However, negative host plant effects, might be overcome through directed selection. We propose that host plant species should be considered when designing biocontrol programs using EPNs. Copyright © 2016 Elsevier Inc. All rights reserved.

Comparative venom toxicity between Pteromalus puparum and Nasonia vitripennis (Hymenoptera: Pteromalidae) toward the hemocytes of their natural hosts, non-target insects and cultured insect cells.

PubMed

Zhang, Zhong; Ye, Gong-Yin; Cai, Jun; Hu, Cui

2005-09-01

Crude venoms from two parasitoid species, Pteromalus puparum and Nasonia vitripennis (Hymenoptera: Pteromalidae) were assayed for biological activities toward hemocytes from two species of their natural hosts and eight species of their non-natural hosts as well as two lines of cultured Lepidoptera cells, respectively. By inhibiting the spreading and viability of insect hemocytes, the venom from P. puparum displayed significantly higher activities toward plasmatocytes and granular cells from both larvae and pupae of two natural hosts, Pieris rapae and Papilio xuthus, and lower activity toward those from Spodoptera litura, Musca domestica and Sarcophaga peregrina. However, no effect was found towards any type of hemocytes from other five insects tested, namely, Ectropis oblique, Galleria mellonella, Sesamia inferens, Bombyx mori and Parnara guttata. In contrast, the venom from N. vitripennis showed a narrower range of targeted insects. It appeared to have highly adverse effects on the spreading and viability of plasmatocytes and granular cells only from the natural hosts, M. domestica and S. peregrina, little toxicity to cells from P. rapae and P. xuthus, and no effect on any of the other insects tested. Pteromalus puparum venom also apparently presented a high ability to block the spreading of Tn-5B1-4 cells derived from Trichoplusia ni, and high cytotoxicity to the cells and Ha cells derived from Helicoverpa armigera. Nasonia vitripennis venom, however, only had a marked lethal effect to Ha cells. In addition, the possibility that the host range of a defined parasitoid could be assessed using our method of treating hemocytes from candidate insects with venom in vitro, and the potential of our venoms tested in the development of bio-insecticides, insect-resistant transgenic plants, are discussed.

Chlorinated hydrocarbons and biomarkers of exposure in wading birds and fish of the Lower Rio Grande Valley, Texas

USGS Publications Warehouse

Wainwright, S.E.; Mora, M.A.; Sericano, J.L.; Thomas, P.

2001-01-01

During 1997 we evaluated reproductive success in colonial water birds nesting in the Lower Rio Grande Valley (LRGV), Texas, and correlated success with concentrations of contaminants in eggs. We also measured steroid hormones and gonadosomatic index (GSI) as biomarkers of endocrine effects in common carp (Cyprinus carpio). Nest and fledging success of green herons (Butorides virescens) and great egrets (Ardea alba) were similar to those found in other parts of North America; however, nesting success of black-crowned night-herons (Nycticorax nycticorax) was lower, very likely due to flooding of the nesting area. Except for DDE and toxaphene, all chlorinated pesticides in bird eggs were low and not of concern for negative effects on any of the three species. DDE was highest in green heron eggs and seemed to increase along a geographic gradient from west to east, with eggs from Falcon Reservoir containing low concentrations, and those at Los Indios containing the highest concentrations (approx. 11,000 ng/g WW), near or above the threshold for reproductive impairment. DDE levels in great egrets and black-crowned night-herons were below those that are associated with reproductive impairment. Mean DDE levels in carp at the JAS Farms site were above the threshold level suggested for predator protection. Toxaphene was detected in about 20% of the samples with high levels observed in green heron eggs from Los Indios (mean = 4,402 ng/g WW). These are the highest toxaphene levels reported in bird eggs in the LRGV. Toxaphene levels in fish ranged between 90 and 312 ng/g WW. In general, PCBs in bird eggs and fish tissue were low and at levels not of concern for reproductive effects. The greatest concentrations of testosterone and 11-ketotestosterone were detected in fish from the JAS Farms site, which also had the greatest concentrations of DDE. Increased androgen production and gonad development in fish at this site, relative to Pharr, could be possibly associated with endocrine disrupting effects of p,p???-DDE. DDE, toxaphene, PCBs, and hormones were highest in birds and fish from the eastern edge of the study area.