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Sample records for orbweaving spider species

  1. Partitioning of niches among four species of orb-weaving spiders in a grassland habitat.

    PubMed

    Richardson, M L; Hanks, L M

    2009-06-01

    Partitioning of niches can play an important role in structuring faunal communities. We tested the hypothesis that differences between four species of orb-weaving spiders (Araneidae) in body size and the structure and position of their webs resulted in their partitioning the available prey. The study species are sympatric in a grassland habitat and included Argiope trifasciata (Forskål), Cyclosa turbinata (Walckenaer), Mangora gibberosa (Hentz), and Neoscona arabesca (Walckenaer). The spider species differed in body size, web diameter, height of web above the ground, spacing of mesh within webs, and the type of plant to which the web was attached. The spider species had a generalist diet and captured prey of multiple trophic levels. Nevertheless, the hypothesis was supported: the spider species differed in the types of prey that they captured. Partitioning of the available prey was influenced by body size, with larger spiders capturing larger prey, but not by the structure or position of their webs. Differences between spider species in niche may reduce competitive interactions and allow them to coexist in sympatry.

  2. The orb-weaving spider genus Chrysometa in Uruguay: distribution and description of a new species (Araneae, Tetragnathidae).

    PubMed

    Simó, Miguel; Álvarez, Luis; Laborda, Álvaro

    2016-01-01

    The spider genus Chrysometa Simon, 1895 comprises 138 species of small (3-5 mm) Neotropical orb-weavers spiders (Nogueira et al. 2011; World Spider Catalogue 2015) mainly associated with arboreal vegetation from intermediate to low altitude forests (Levi 1986). Males of Chrysometa differ from other tetragnathids by having the palpal tibial length approximately as long as its widest point; paracymbium articulated and with several apophyses located at both ends; male cephalic region narrower than in the female and having cymbial ectobasal and ectomedian processes. Females are diagnosed by having femora without trichobothria; abdomen covered with silver guanine patches; a flat epigynum and also by their fertilization ducts originating anteriorly and crossing over the spermathecae (Levi 1986; Alvarez-Padilla & Hormiga 2011). PMID:27395900

  3. Systematics, phylogeny, and evolution of orb-weaving spiders.

    PubMed

    Hormiga, Gustavo; Griswold, Charles E

    2014-01-01

    The orb-weaving spiders (Orbiculariae) comprise more than 25% of the approximately 44,000 known living spider species and produce a remarkable variety of webs. The wheel-shaped orb web is primitive to this clade, but most Orbiculariae make webs hardly recognizable as orbs. Orb-weavers date at least to the Jurassic. With no evidence for convergence of the orb web, the monophyly of the two typical orb web taxa, the cribellate Deinopoidea and ecribellate Araneoidea, remains problematic, supported only weakly by molecular studies. The sister group of the Orbiculariae also remains elusive. Despite more than 15 years of phylogenetic scrutiny, a fully resolved cladogram of the Orbiculariae families is not yet possible. More comprehensive taxon sampling, comparative morphology, and new molecular markers are required for a better understanding of orb-weaver evolution.

  4. Combining morphology, DNA sequences, and morphometrics: revising closely related species in the orb-weaving spider genus Araniella (Araneae, Araneidae).

    PubMed

    Spasojevic, Tamara; Kropf, Christian; Nentwig, Wolfgang; Lasut, Liana

    2016-01-01

    The integration of independent data sets could solve problems in both traditional and DNA-based taxonomy. The aim of this study is to investigate the power of CO1 sequences and of morphometrics to distinguish closely related species in the spider genus Araniella. We put special emphasis on the species pair A. cucurbitina (Clerck, 1757) and A. opisthographa (Kulczyński, 1905) since the females are morphologically difficult to distinguish and often misidentified. A total of 216 sequences of eight Araniella species from seven European countries, North America and Asia were included in the molecular analysis. The results from both maximum likelihood and Bayesian phylogenetic inference indicate successful separation of six out of eight Araniella species, including A. cucurbitina and A. opisthographa. For the same six species, we detect no overlap of intra- and interspecific genetic divergence, leading to successful species identification with a threshold approach. In addition, morphometric analysis of the epigyna of A. cucurbitina and A. opisthographa supports species separation by two best explanatory ratios: receptaculum length and distance between receptaculum and copulatory duct. Although a small overlap in the ratios exists, the species identification rate increases when combining morphometric and molecular data, which demonstrates the efficiency of integrative approaches for distinguishing closely related species. However, none of the molecular approaches was able to separate closely related A. alpica (L. Koch, 1869) and A. inconspicua (Simon, 1874) due to shared CO1 haplotypes. Considering the clear morphological separation of the males and different habitat preferences, incomplete lineage sorting or introgressive hybridization could have led to identical CO1 sequences. Therefore, DNA-barcoding must be thoroughly tested even within small homogenous genera of spiders. PMID:27395098

  5. Loss of legs: is it or not a handicap for an orb-weaving spider?

    PubMed

    Pasquet, Alain; Anotaux, Mylène; Leborgne, Raymond

    2011-07-01

    Leg loss is a common phenomenon in spiders, and according to the species 5% to 40% of the adults can present at least one missing leg. There is no possibility of regeneration after adult moult and the animal must manage with its missing appendages until its death. With the loss of one or more legs, female orb-weaving spiders can be penalized twice: firstly, because the legs are necessary for web construction and secondly, the legs are essential for the control of the prey after its interception by the web. During development, spiders may be also penalized because regeneration has energetic costs that take away resources for survival, growth and reproduction. All these consequences should influence negatively the development of the spider and thus its fitness. We investigated the impact of leg loss in the orb-weaving spider, Zygiella x-notata by studying its frequency in a natural population and web building and prey capture behaviours in laboratory. In field populations, 9.5% to 13%, of the adult females presented the loss of one or more legs; the majority of individuals had lost only one leg (in 48% of cases, a first one). Leg loss seems to affect all the adult spiders, as there is no difference of mass between intact spiders and those with missing leg. Data obtained with laboratory-reared spiders, showed that the loss of legs due to the moult is rare (less than 1%). Considering changes in web design, spiders with missing legs decreased their silk investment, increased the distance between spiral turns but did not change the capture surface of the web. Under our laboratory experimental conditions, spiders with one or two lost legs did not present any difference in prey capture efficiency. In laboratory conditions, spiders with lost leg(s) did not show any difference in egg sac production or in longevity (adult lifespan) compared to intact spiders. PMID:21533554

  6. Loss of legs: is it or not a handicap for an orb-weaving spider?

    NASA Astrophysics Data System (ADS)

    Pasquet, Alain; Anotaux, Mylène; Leborgne, Raymond

    2011-07-01

    Leg loss is a common phenomenon in spiders, and according to the species 5% to 40% of the adults can present at least one missing leg. There is no possibility of regeneration after adult moult and the animal must manage with its missing appendages until its death. With the loss of one or more legs, female orb-weaving spiders can be penalized twice: firstly, because the legs are necessary for web construction and secondly, the legs are essential for the control of the prey after its interception by the web. During development, spiders may be also penalized because regeneration has energetic costs that take away resources for survival, growth and reproduction. All these consequences should influence negatively the development of the spider and thus its fitness. We investigated the impact of leg loss in the orb-weaving spider, Zygiella x-notata by studying its frequency in a natural population and web building and prey capture behaviours in laboratory. In field populations, 9.5% to 13%, of the adult females presented the loss of one or more legs; the majority of individuals had lost only one leg (in 48% of cases, a first one). Leg loss seems to affect all the adult spiders, as there is no difference of mass between intact spiders and those with missing leg. Data obtained with laboratory-reared spiders, showed that the loss of legs due to the moult is rare (less than 1%). Considering changes in web design, spiders with missing legs decreased their silk investment, increased the distance between spiral turns but did not change the capture surface of the web. Under our laboratory experimental conditions, spiders with one or two lost legs did not present any difference in prey capture efficiency. In laboratory conditions, spiders with lost leg(s) did not show any difference in egg sac production or in longevity (adult lifespan) compared to intact spiders.

  7. An orb-weaver spider exploits an ant–acacia mutualism for enemy-free space

    PubMed Central

    Styrsky, John D

    2014-01-01

    Exploiters of protection mutualisms are assumed to represent an important threat for the stability of those mutualisms, but empirical evidence for the commonness or relevance of exploiters is limited. Here, I describe results from a manipulative study showing that an orb-weaver spider, Eustala oblonga, inhabits an ant-acacia for protection from predators. This spider is unique in the orb-weaver family in that it associates closely with both a specific host plant and ants. I tested the protective effect of acacia ants on E. oblonga by comparing spider abundance over time on acacias with ants and on acacias from which entire ant colonies were experimentally removed. Both juvenile and adult spider abundance significantly decreased over time on acacias without ants. Concomitantly, the combined abundance of potential spider predators increased over time on acacias without ants. These results suggest that ant protection of the ant-acacia Acacia melanocerus also protects the spiders, thus supporting the hypothesis that E. oblonga exploits the ant–acacia mutualism for enemy-free space. Although E. oblonga takes advantage of the protection services of ants, it likely exacts little to no cost and should not threaten the stability of the ant–acacia mutualism. Indeed, the potential threat of exploiter species to protection mutualisms in general may be limited to species that exploit the material rewards traded in such mutualisms rather than the protection services. PMID:24558583

  8. Herbivory in spiders: the importance of pollen for orb-weavers.

    PubMed

    Eggs, Benjamin; Sanders, Dirk

    2013-01-01

    Orb-weaving spiders (Araneidae) are commonly regarded as generalist insect predators but resources provided by plants such as pollen may be an important dietary supplementation. Their webs snare insect prey, but can also trap aerial plankton like pollen and fungal spores. When recycling their orb webs, the spiders may therefore also feed on adhering pollen grains or fungal spores via extraoral digestion. In this study we measured stable isotope ratios in the bodies of two araneid species (Aculepeira ceropegia and Araneus diadematus), their potential prey and pollen to determine the relative contribution of pollen to their diet. We found that about 25% of juvenile orb-weaving spiders' diet consisted of pollen, the other 75% of flying insects, mainly small dipterans and hymenopterans. The pollen grains in our study were too large to be taken up accidentally by the spiders and had first to be digested extraorally by enzymes in an active act of consumption. Therefore, pollen can be seen as a substantial component of the spiders' diet. This finding suggests that these spiders need to be classified as omnivores rather than pure carnivores.

  9. The allometry of CNS size and consequences of miniaturization in orb-weaving and cleptoparasitic spiders.

    PubMed

    Quesada, Rosannette; Triana, Emilia; Vargas, Gloria; Douglass, John K; Seid, Marc A; Niven, Jeremy E; Eberhard, William G; Wcislo, William T

    2011-11-01

    Allometric studies of the gross neuroanatomy of adults from nine species of spiders from six web-weaving families (Orbicularia), and nymphs from six of these species, show that very small spiders resemble other small animals in having disproportionately larger central nervous systems (CNSs) relative to body mass when compared with large-bodied forms. Small spiderlings and minute adult spiders have similar relative CNS volumes. The relatively large CNS of a very small spider occupies up to 78% of the cephalothorax volume. The CNSs of very small spiders extend into their coxae, occupying as much as 26% of the profile area of the coxae of an Anapisona simoni spiderling (body mass < 0.005 mg). Such modifications occur both in species with minute adults, and in tiny spiderlings of species with large-bodied adults. In at least one such species, Leucauge mariana, the CNS of the spiderling extends into a prominent ventral bulge of the sternum. Tiny spiders also have reduced neuronal cell body diameters. The adults of nearly all orbicularian spiders weave prey capture webs, as do the spiderlings, beginning with second instar nymphs. Comparable allometric relations occur in adults of both orb-weaving and cleptoparasitic species, indicating that this behavioral difference is not reflected in differences in gross CNS allometry. PMID:22036838

  10. Effects of kaolin particle films on the life span of an orb-weaver spider.

    PubMed

    Benhadi-Marín, Jacinto; Pereira, José Alberto; Santos, Sónia A P

    2016-02-01

    Araniella cucurbitina (Araneae: Araneidae) is a widespread orb-weaver spider commonly found in agroecosystems. Mineral particle films such as kaolin, due to their protective or anti-feeding action, can represent an alternative to pesticides, especially in organic farming systems, but little is known about its effects on A. cucurbitina. Therefore, we tested the effect of kaolin sprays on the life span of A. cucurbitina under laboratory conditions. Four treatments were tested encompassing different exposure routes. Thus, kaolin sprays were applied on (i) the surface, (ii) the prey (fly), (iii) the spider and (iv) both spider & prey. A control group was tested with water in each treatment. Results showed that sprays of kaolin significantly affected the survival of A. curcubitina when applications were done on the surface and on both spider & prey registering a reduction of 48% and 56%, respectively. Spiders in control obtained higher probability of reaching alive at the end of the assay than those treated with kaolin. Differences observed can be explained by the feeding behavior of the species and may depend on the consumption of the web by the spider and the ratio spider/fly for body size.

  11. Evolution of supercontraction in spider silk: structure-function relationship from tarantulas to orb-weavers.

    PubMed

    Boutry, Cecilia; Blackledge, Todd Alan

    2010-10-15

    Spider silk is a promising biomaterial with impressive performance. However, some spider silks also 'supercontract' when exposed to water, shrinking by up to ∼50% in length. Supercontraction may provide a critical mechanism to tailor silk properties, both for future synthetic silk production and by the spiders themselves. Several hypotheses are proposed for the mechanism and function of supercontraction, but they remain largely untested. In particular, supercontraction may result from a rearrangement of the GPGXX motif within the silk proteins, where G represents glycine, P proline and X is one of a small subset of amino acids. Supercontraction may prevent sagging in wet orb-webs or allow spiders to tailor silk properties for different ecological functions. Because both the molecular structures of silk proteins and how dragline is used in webs differ among species, we can test these hypotheses by comparing supercontraction of silk across diverse spider taxa. In this study we measured supercontraction in 28 spider taxa, ranging from tarantulas to orb-weaving spiders. We found that silk from all species supercontracted, except that of most tarantulas. This suggests that supercontraction evolved at least with the origin of the Araneomorphae, over 200 million years ago. We found differences in the pattern of evolution for two components of supercontraction. Stress generated during supercontraction of a restrained fiber is not associated with changes in silk structure and web architecture. By contrast, the shrink of unrestrained supercontracting fibers is higher for Orbiculariae spiders, whose silk contains high ratios of GPGXX motifs. These results support the hypothesis that supercontraction is caused by a rearrangement of GPGXX motifs in silk, and that it functions to tailor silk material properties.

  12. Evolution of supercontraction in spider silk: structure-function relationship from tarantulas to orb-weavers.

    PubMed

    Boutry, Cecilia; Blackledge, Todd Alan

    2010-10-15

    Spider silk is a promising biomaterial with impressive performance. However, some spider silks also 'supercontract' when exposed to water, shrinking by up to ∼50% in length. Supercontraction may provide a critical mechanism to tailor silk properties, both for future synthetic silk production and by the spiders themselves. Several hypotheses are proposed for the mechanism and function of supercontraction, but they remain largely untested. In particular, supercontraction may result from a rearrangement of the GPGXX motif within the silk proteins, where G represents glycine, P proline and X is one of a small subset of amino acids. Supercontraction may prevent sagging in wet orb-webs or allow spiders to tailor silk properties for different ecological functions. Because both the molecular structures of silk proteins and how dragline is used in webs differ among species, we can test these hypotheses by comparing supercontraction of silk across diverse spider taxa. In this study we measured supercontraction in 28 spider taxa, ranging from tarantulas to orb-weaving spiders. We found that silk from all species supercontracted, except that of most tarantulas. This suggests that supercontraction evolved at least with the origin of the Araneomorphae, over 200 million years ago. We found differences in the pattern of evolution for two components of supercontraction. Stress generated during supercontraction of a restrained fiber is not associated with changes in silk structure and web architecture. By contrast, the shrink of unrestrained supercontracting fibers is higher for Orbiculariae spiders, whose silk contains high ratios of GPGXX motifs. These results support the hypothesis that supercontraction is caused by a rearrangement of GPGXX motifs in silk, and that it functions to tailor silk material properties. PMID:20889831

  13. Niche partitioning in orbweaving spiders Meta menardi and Metellina merianae (Tetragnathidae)

    NASA Astrophysics Data System (ADS)

    Novak, Tone; Tkavc, Tina; Kuntner, Matjaž; Arnett, Amy E.; Delakorda, Saška Lipovšek; Perc, Matjaž; Janžekovič, Franc

    2010-11-01

    Hypogean habitats are relatively simple exhibiting low diversity, low production and relative constancy of environmental factors, and are therefore appropriate for studying species coexistence in situ. We investigated the coexistence of two closely related, similarly sized orb-weaving spider species, Meta menardi and Metellina merianae, living syntopically in a Slovenian cave. We studied the annual dynamics of both species within a mixed population, and the impact of the ambient temperature, relative humidity, airflow and illumination, and compared their trophic niches to legacy data on prey of both species from 55 caves in Slovenia. We predicted a large overlap in their spatial niches and substantial differences in their temporal and trophic niches. We found that their spatial niches overlap greatly with few exceptions, mostly on the dates of notable meteorological changes in the cave but that their temporal niches differ significantly with r-strategy resembling epigean annual dynamic in M. merianae and a steady low abundance course in M. menardi within the cave. We also found that different predatory strategies significantly segregate their trophic niches: M. merianae uses a typical orb-weaving hunting strategy, while M. menardi combines web hunting with off-web hunting. Our findings suggest that both the diverse dynamics and trophic niches enable the coexistence of M. menardi and M. merianae despite their similar spatial niches, and that M. menardi, in particular, is optimally adapted to the epigean/hypogean ecotone.

  14. Spontaneous male death during copulation in an orb-weaving spider.

    PubMed Central

    Foellmer, Matthias W; Fairbairn, Daphne J

    2003-01-01

    Males of some cannibalistic species of spiders and insects appear to sacrifice themselves by allowing the female to eat them, and the adaptive significance of such drastic terminal reproductive investment has recently been demonstrated for a spider. Typically, the female has to kill the male, but it has been suggested that males of some species in the cannibalistic orb-weaving spider genus Argiope may die in copula without female 'collaboration'. Here, we provide the first experimental evidence to our knowledge of programmed sudden death after onset of copulation in males of the spider Argiope aurantia. Our observations reveal that males invariably die during the insertion of their second pedipalp, regardless of whether they mate with newly moulted, defenceless females or with older mature females that often attack them. We determined experimentally that the death of males is triggered immediately upon insertion of the second palp, when males become unresponsive, and heartbeat ceases within minutes of insertion. We discuss the possible adaptive significance of programmed death during copulation, and argue that male death has evolved in a context other than sexual cannibalism. PMID:14667377

  15. Competing dwarf males: sexual selection in an orb-weaving spider.

    PubMed

    Foellmer, M W; Fairbairn, D J

    2005-05-01

    Hypotheses for the adaptive significance of extreme female-biased sexual size dimorphism (SSD) generally assume that in dimorphic species males rarely interfere with each other. Here we provide the first multivariate examination of sexual selection because of male-male competition over access to females in a species with 'dwarf' males, the orb-weaving spider Argiope aurantia. Male A. aurantia typically try to mate opportunistically during the female's final moult when she is defenceless. We show that, contrary to previous hypotheses, the local operational sex ratio (males per female on the web) is male-biased most of the season. Both interference and scramble competition occur during opportunistic mating, the former leading to significant selection for large male body size. Male condition and leg length had no effect on mating success independent of size. We discuss these findings in the context of the evolution of extreme female-biased SSD in this clade.

  16. Do parasitoids explain differential abundance of two syntopic orb-weaver spiders (Araneae: Araneidae)?

    NASA Astrophysics Data System (ADS)

    Gonzaga, Marcelo O.; Cardoso, João C. F.; Vasconcellos-Neto, João

    2015-11-01

    In this study, we examined the relative abundance of two congeneric species of orb-weaver spiders, Cyclosa fililineata and Cyclosa morretes, in an area of Atlantic forest in southeastern Brazil, and the relationship of this variable with fecundity and attacks by parasitoids. We also investigated responses to vibrational stimuli that simulated the approach of a wasp and described architectural changes in webs of parasitized individuals of C. fililineata. C.fililineata was more abundant throughout the year, although this species produced a lower number of egg sacs and a lower number of eggs per egg sac when compared with C. morretes. Both species showed similar types of behavioral responses to vibrational stimuli, but C. fililineata remained motionless more often. The frequency of parasitism by the wasp Polysphincta janzeni on adults and juveniles was low and similar for C. fililineata and C. morretes in both dry and wet seasons. The parasitoid caused alterations in the web design of C. fililineata similar of those observed in other orb-weavers attacked by ichneumonid wasps. Webs constructed by spiders parasitized by larvae in their last instar had a lower number of radii and sticky spirals were completely absent. An egg parasitoid, Baeus cyclosae, attacked C. morretes more often than C. fililineata, possibly as a consequence of its greater clutch size and/or larger eggs. These results indicate that egg mortality caused by B. cyclosae, but not subadult and adult mortality promoted by P. janzeni, may be an important factor determining the relative abundance of these two Cyclosa species.

  17. Modular evolution of egg case silk genes across orb-weaving spider superfamilies

    PubMed Central

    Garb, Jessica E.; Hayashi, Cheryl Y.

    2005-01-01

    Spider silk proteins (fibroins) are renowned for their extraordinary mechanical properties and biomimetic potential. Despite extensive evolutionary, ecological, and industrial interest in these fibroins, only a fraction of the known silk types have been characterized at the molecular level. Here we report cDNA and genomic sequences of the fibroin TuSp1, which appears to be the major component of tubuliform gland silk, a fiber exclusively synthesized by female spiders for egg case construction. We obtained TuSp1 sequences from 12 spider species that represent the extremes of phylogenetic diversity within the Orbicularia (orb-weaver superfamilies, Araneoidea and Deinopoidea) and finer scale sampling within genera. TuSp1 encodes tandem arrays of an ≈200-aa-long repeat unit and individual repeats are readily aligned, even among species that diverged >125 million years ago. Analyses of these repeats across species reveal the strong influence of concerted evolution, resulting in intragenic homogenization. However, deinopoid TuSp1 repeats also contain insertions of coding, minisatellite-like sequences, an apparent result of replication slippage and nonreciprocal recombination. Phylogenetic analyses of 37 spider fibroin sequences support the monophyly of TuSp1 within the spider fibroin gene family, consistent with a single origin of this ortholog group. The diversity of taxa and silks examined here confirms that repetitive architecture is a general feature of this gene family. Moreover, we show that TuSp1 provides a clear example of modular evolution across a range of phylogenetic levels. PMID:16061817

  18. Oldest true orb-weaving spider (Araneae: Araneidae).

    PubMed

    Penney, David; Ortuño, Vicente M

    2006-09-22

    The aerial orb web woven by spiders of the family Araneidae typifies these organisms to laypersons and scientists alike. Here we describe the oldest fossil species of this family, which is preserved in amber from Alava, Spain and represents the first record of Araneidae from the Lower Cretaceous. The fossils provide direct evidence that all three major orb web weaving families: Araneidae, Tetragnathidae and Uloboridae had evolved by this time, confirming the antiquity of the use of this remarkable structure as a prey capture strategy by spiders. Given the complex and stereotyped movements that all orb weavers use to construct their webs, there is little question regarding their common origin, which must have occurred in the Jurassic or earlier. Thus, various forms of this formidable prey capture mechanism were already in place by the time of the explosive Cretaceous co-radiation of angiosperms and their flying insect pollinators. This permitted a similar co-radiation of spider predators with their flying insect prey, presumably without the need for a 'catch-up lag phase' for the spiders.

  19. A golden orb-weaver spider (Araneae: Nephilidae: Nephila) from the Middle Jurassic of China.

    PubMed

    Selden, Paul A; Shih, ChungKun; Ren, Dong

    2011-10-23

    Nephila are large, conspicuous weavers of orb webs composed of golden silk, in tropical and subtropical regions. Nephilids have a sparse fossil record, the oldest described hitherto being Cretaraneus vilaltae from the Cretaceous of Spain. Five species from Neogene Dominican amber and one from the Eocene of Florissant, CO, USA, have been referred to the extant genus Nephila. Here, we report the largest known fossil spider, Nephila jurassica sp. nov., from Middle Jurassic (approx. 165 Ma) strata of Daohugou, Inner Mongolia, China. The new species extends the fossil record of the family by approximately 35 Ma and of the genus Nephila by approximately 130 Ma, making it the longest ranging spider genus known. Nephilidae originated somewhere on Pangaea, possibly the North China block, followed by dispersal almost worldwide before the break-up of the supercontinent later in the Mesozoic. The find suggests that the palaeoclimate was warm and humid at this time. This giant fossil orb-weaver provides evidence of predation on medium to large insects, well known from the Daohugou beds, and would have played an important role in the evolution of these insects.

  20. A golden orb-weaver spider (Araneae: Nephilidae: Nephila) from the Middle Jurassic of China

    PubMed Central

    Selden, Paul A.; Shih, ChungKun; Ren, Dong

    2011-01-01

    Nephila are large, conspicuous weavers of orb webs composed of golden silk, in tropical and subtropical regions. Nephilids have a sparse fossil record, the oldest described hitherto being Cretaraneus vilaltae from the Cretaceous of Spain. Five species from Neogene Dominican amber and one from the Eocene of Florissant, CO, USA, have been referred to the extant genus Nephila. Here, we report the largest known fossil spider, Nephila jurassica sp. nov., from Middle Jurassic (approx. 165 Ma) strata of Daohugou, Inner Mongolia, China. The new species extends the fossil record of the family by approximately 35 Ma and of the genus Nephila by approximately 130 Ma, making it the longest ranging spider genus known. Nephilidae originated somewhere on Pangaea, possibly the North China block, followed by dispersal almost worldwide before the break-up of the supercontinent later in the Mesozoic. The find suggests that the palaeoclimate was warm and humid at this time. This giant fossil orb-weaver provides evidence of predation on medium to large insects, well known from the Daohugou beds, and would have played an important role in the evolution of these insects. PMID:21508021

  1. Adhesive recruitment by the viscous capture threads of araneoid orb-weaving spiders.

    PubMed

    Opell, Brent D; Hendricks, Mary L

    2007-02-01

    The sticky prey capture threads of orb-webs are critical to web performance. By retaining insects that strike the web, these spirally arrayed threads allow a spider time to locate and subdue prey. The viscous capture threads spun by modern orb-weaving spiders of the Araneoidea clade replaced the dry, fuzzy cribellar capture threads of the Deinopoidea and feature regularly spaced moist, adhesive droplets. The stickiness of a cribellar thread is limited by its tendency to peel from a surface after the adhesion generated at the edges of contact is exceeded. In this study we test the hypothesis that viscous thread overcomes this limitation by implementing a suspension bridge mechanism (SBM) that recruits the adhesion of multiple thread droplets. We do so by using contact plates of four widths to measure the stickiness of six species' viscous threads whose profiles range from small, closely spaced droplets to large, widely spaced droplets. The increased stickiness registered by an increased number of thread droplets supports the operation of a SBM. However, the accompanying decrease in mean per droplet adhesion shows that droplets interior to the edges of thread contact contribute successively less adhesion. Models developed from these data suggest that the suspension bridge mechanism is limited to a span of approximately 12 droplets.

  2. Unraveling the mechanical properties of composite silk threads spun by cribellate orb-weaving spiders.

    PubMed

    Blackledge, Todd A; Hayashi, Cheryl Y

    2006-08-01

    Orb-web weaving spiders depend upon the mechanical performance of capture threads to absorb the energy of flying prey. Most orb-weavers spin wet capture threads with core fibers of flagelliform silk. These threads are extremely compliant and extensible due to the folding of their constituent proteins into molecular nanosprings and hydration by a surrounding coating of aqueous glue. In contrast, other orb-weavers use cribellate capture threads, which are composite structures consisting of core fibers of pseudoflagelliform silk surrounded by a matrix of fine dry cribellar fibrils. Based on phylogenetic evidence, cribellate capture threads predate the use of viscid capture threads. To better characterize how pseudoflagelliform and cribellar fibrils function, we investigated the mechanical performance of cribellate capture threads for three genera of spiders (Deinopis, Hyptiotes and Uloborus). These taxa spin very diverse web architectures, ranging from complete orbs to evolutionarily reduced triangle webs and cast nets. We found that the pseudoflagelliform core fibers of these webs were stiffer and stronger, but also less extensible, than flagelliform silk. However, cribellate capture threads achieved overall high extensibilities because the surrounding cribellar fibrils contributed substantially to the tensile performance of threads long after the core pseudoflagelliform fibers ruptured. In the case of Deinopis capture threads, up to 90% of the total work performed could be attributed to these fibrils. These findings yield insight into the evolutionary transition from cribellate to viscid capture threads.

  3. Detritus decorations of an orb-weaving spider, Cyclosa mulmeinensis (Thorell): for food or camouflage?

    PubMed

    Tan, Eunice J; Li, Daiqin

    2009-06-01

    Many species of the orb-web spider genus Cyclosa often adorn their webs with decorations of prey remains, egg sacs and/or plant detritus, termed ;detritus decorations'. These detritus decorations have been hypothesised to camouflage the spider from predators or prey and thus reduce predation risk or increase foraging success. In the present study, we tested these two alternative hypotheses simultaneously using two types of detritus decorations (prey remain and egg sac) built by Cyclosa mulmeinensis (Thorell). By monitoring the possible responses of predators to spiders on their webs with and without decorations in the field, we tested whether web decorations would reduce the mortality of spiders. Wasp predators were observed to fly in the vicinity of webs with decorations slightly more often than in the vicinity of webs without decorations but there were very few attacks on spiders by wasps. By comparing the insect interception rates of webs with and without decorations in the field, we tested whether web decorations would increase the foraging success. Webs decorated with prey remains or egg sacs intercepted more insects than those without in the field. By calculating colour contrasts of both prey-remain and egg-sac decorations against spiders viewed by bird (blue tits) and hymenopteran (e.g. wasps) predators as well as hymenopteran (bees) prey, we showed that C. mulmeinensis spiders on webs with egg-sac decorations were invisible to both hymenopteran prey and predators and bird predators over short and long distances. While spiders on webs with prey-remain decorations were invisible to both hymenopterans and birds over short distances, spiders on webs with prey-remain decorations were visible to both predators and prey over long distances. Our results thus suggest that decorating webs with prey remains and egg sacs in C. mulmeinensis may primarily function as camouflage to conceal the spider from insects rather than as prey attractants, possibly contributing to

  4. The impact of UVB radiation on the glycoprotein glue of orb-weaving spider capture thread.

    PubMed

    Stellwagen, Sarah D; Opell, Brent D; Clouse, Mary E

    2015-09-01

    Many spider orb-webs are exposed to sunlight and the potentially damaging effects of ultraviolet B (UVB) radiation. We examined the effect of UVB on the viscoelastic glycoprotein core of glue droplets deposited on the prey capture threads of these webs, hypothesizing that webs built by species that occupy sunny habitats are less susceptible to UVB damage than are webs built by species that prefer shaded forest habitats or by nocturnal species. Threads were tested shortly after being collected in the early morning and after being exposed to UVB energy equivalent to a day of summer sun and three times this amount. Droplets kept in a dark chamber allowed us to evaluate post-production changes. Droplet volume was unaffected by treatments, indicating that UVB did not damage the hygroscopic compounds in the aqueous layer that covers droplets. UVB exposure did not affect energies of droplet extension for species from exposed and partially to mostly shaded habitats (Argiope aurantia, Leucauge venusta and Verrucosa arenata). However, UVB exposure reduced the energy of droplet extension in Micrathena gracilis from shaded forests and Neoscona crucifera, which forages at night. Only in L. venusta did the energy of droplet extension increase after the dark treatment, suggesting endogenous molecular alignment. This study adds UVB irradiation to the list of factors (humidity, temperature and strain rate) known to affect the performance of spider glycoprotein glue, factors that must be more fully understood if adhesives that mimic spider glycoprotein glue are to be produced. PMID:26333924

  5. The impact of UVB radiation on the glycoprotein glue of orb-weaving spider capture thread.

    PubMed

    Stellwagen, Sarah D; Opell, Brent D; Clouse, Mary E

    2015-09-01

    Many spider orb-webs are exposed to sunlight and the potentially damaging effects of ultraviolet B (UVB) radiation. We examined the effect of UVB on the viscoelastic glycoprotein core of glue droplets deposited on the prey capture threads of these webs, hypothesizing that webs built by species that occupy sunny habitats are less susceptible to UVB damage than are webs built by species that prefer shaded forest habitats or by nocturnal species. Threads were tested shortly after being collected in the early morning and after being exposed to UVB energy equivalent to a day of summer sun and three times this amount. Droplets kept in a dark chamber allowed us to evaluate post-production changes. Droplet volume was unaffected by treatments, indicating that UVB did not damage the hygroscopic compounds in the aqueous layer that covers droplets. UVB exposure did not affect energies of droplet extension for species from exposed and partially to mostly shaded habitats (Argiope aurantia, Leucauge venusta and Verrucosa arenata). However, UVB exposure reduced the energy of droplet extension in Micrathena gracilis from shaded forests and Neoscona crucifera, which forages at night. Only in L. venusta did the energy of droplet extension increase after the dark treatment, suggesting endogenous molecular alignment. This study adds UVB irradiation to the list of factors (humidity, temperature and strain rate) known to affect the performance of spider glycoprotein glue, factors that must be more fully understood if adhesives that mimic spider glycoprotein glue are to be produced.

  6. Miniaturized orb-weaving spiders: behavioural precision is not limited by small size.

    PubMed

    Eberhard, William G

    2007-09-01

    The special problems confronted by very small animals in nervous system design that may impose limitations on their behaviour and evolution are reviewed. Previous attempts to test for such behavioural limitations have suffered from lack of detail in behavioural observations of tiny species and unsatisfactory measurements of their behavioural capacities. This study presents partial solutions to both problems. The orb-web construction behaviour of spiders provided data on the comparative behavioural capabilities of tiny animals in heretofore unparalleled detail; species ranged about five orders of magnitude in weight, from approximately 50-100mg down to some of the smallest spiders known (less than 0.005mg), whose small size is a derived trait. Previous attempts to quantify the 'complexity' of behaviour were abandoned in favour of using comparisons of behavioural imprecision in performing the same task. The prediction of the size limitation hypothesis that very small spiders would have a reduced ability to repeat one particular behaviour pattern precisely was not confirmed. The anatomical and physiological mechanisms by which these tiny animals achieve this precision and the possibility that they are more limited in the performance of higher-order behaviour patterns await further investigation.

  7. Revision and phylogenetic analysis of the orb-weaving spider genus Glenognatha Simon, 1887 (Araneae, Tetragnathidae).

    PubMed

    Cabra-García, Jimmy; Brescovit, Antonio D

    2016-01-01

    A taxonomic revision and phylogenetic analysis of the spider genus Glenognatha Simon, 1887 is presented. This analysis is based on a data set including 24 Glenognatha species plus eight outgroups representing three related tetragnathine genera and one metaine as the root. These taxa were scored for 78 morphological characters. Parsimony was used as the optimality criterion and a sensitivity analysis was performed using different character weighting concavities. Seven unambiguous synapomorphies support the monophyly of Glenognatha. Some internal clades within the genus are well-supported and its relationships are discussed. Glenognatha as recovered includes 27 species, four of them only known from males. A species identification key and distribution maps are provided for all. New morphological data are also presented for thirteen previously described species. Glenognatha has a broad distribution occupying the Neartic, Afrotropic, Indo-Malaya, Oceania and Paleartic regions, but is more diverse in the Neotropics. The following eleven new species are described: G. vivianae n. sp., G. caaguara n. sp., G. boraceia n. sp. and G. timbira n. sp. from southeast Brazil, G. caparu n. sp., G. januari n. sp. and G. camisea n. sp. from the Amazonian region, G. mendezi n. sp., G. florezi n. sp. and G. patriceae n. sp. from northern Andes and G. gouldi n. sp. from Southern United States and central Mexico. Females of G. minuta Banks, 1898, G. gaujoni Simon, 1895 and G. gloriae (Petrunkevitch, 1930) and males of G. globosa (Petrunkevitch, 1925) and G. hirsutissima (Berland, 1935) are described for the first time. Three new combinations are proposed in congruence with the phylogenetic results: G. argyrostilba (O. P.-Cambridge, 1876) n. comb., G. dentata (Zhu & Wen, 1978) n. comb. and G. tangi (Zhu, Song & Zhang, 2003) n. comb., all previously included in Dyschiriognatha Simon, 1893. The following taxa are newly synonymized: Dyschiriognatha montana Simon, 1897, Glenognatha mira Bryant

  8. The role of granules within viscous capture threads of orb-weaving spiders.

    PubMed

    Opell, B D; Hendricks, M L

    2010-01-15

    Sticky viscous prey capture threads form the spiral elements of spider orb-webs and are responsible for retaining insects that strike a web. These threads are formed of regularly spaced aqueous droplets that surround a pair of supporting axial fibers. When a thread is flattened on a microscope slide a small, opaque granule can usually be seen within each droplet. These granules have been thought to be the glycoprotein glue that imparts thread adhesion. Both independent contrast and standard regressions showed that granule size is directly related to droplet volume and indicated that granule volume is about 15% of droplet volume. We attempted to find support for the hypothesized adhesive role of granules by establishing an association between the contact surface area and volume of these granules and the stickiness of the viscous threads of 16 species in the context of a six-variable model that describes thread stickiness. However, we found that granule size made either an insignificant or a small negative contribution to thread stickiness. Consequently, we hypothesize that granules serve to anchor larger, surrounding layers of transparent glycoprotein glue to the axial fibers of the thread, thereby equipping droplets to resist slippage on the axial fibers as these droplets generate adhesion, elongate under a load, and transfer force to the axial fibers.

  9. Adhesive compatibility of cribellar and viscous prey capture threads and its implication for the evolution of orb-weaving spiders.

    PubMed

    Opell, Brent D; Tran, Andrew M; Karinshak, Shannon E

    2011-07-01

    Evolution of orb-weaving spiders that comprise the Orbiculariae clade involved a transition in the composition of prey capture thread that has been challenging to explain. The primitive cribellar threads spun by members of the Deinopoidea subclade resemble the capture threads of their non-orb-web-weaving ancestors and are formed of thousands of fine, dry, protein cribellar fibrils. In contrast, the derived viscous capture threads spun by members of the Araneoidea subclade have regularly spaced, aqueous adhesive droplets. When second instar deinopoid spiderlings emerge from egg sacs they are unable to spin cribellar threads, and, therefore, do not construct orb-webs; whereas second instar araneoids spin capture threads and construct orb-webs. If, as we hypothesize, viscous material evolved to enable second instar spiderlings to construct orb-webs, early araneoids may have spun composite cribellar-viscous capture threads. To examine the functional feasibility of such intermediate capture threads, we compared the adhesion of cribellar threads, viscous threads, and combined cribellar-viscous threads. The stickiness of these combined threads was greater than that of native cribellar or viscous threads alone. The viscous material of Araneus marmoreus threads exhibited a substantial increase in stickiness when combined with cribellar fibrils and that of Argiope aurantia threads a small increase in stickiness when combined with cribellar fibrils. Thus, if early araneoids retained their ability to spin cribellar threads after having evolved glands that produced viscous material, their composite threads could have formed a functional adhesive system that achieved its stickiness at no loss of material economy.

  10. Urbanisation at Multiple Scales Is Associated with Larger Size and Higher Fecundity of an Orb-Weaving Spider

    PubMed Central

    Lowe, Elizabeth C.; Wilder, Shawn M.; Hochuli, Dieter F.

    2014-01-01

    Urbanisation modifies landscapes at multiple scales, impacting the local climate and changing the extent and quality of natural habitats. These habitat modifications significantly alter species distributions and can result in increased abundance of select species which are able to exploit novel ecosystems. We examined the effect of urbanisation at local and landscape scales on the body size, lipid reserves and ovary weight of Nephila plumipes, an orb weaving spider commonly found in both urban and natural landscapes. Habitat variables at landscape, local and microhabitat scales were integrated to create a series of indexes that quantified the degree of urbanisation at each site. Spider size was negatively associated with vegetation cover at a landscape scale, and positively associated with hard surfaces and anthropogenic disturbance on a local and microhabitat scale. Ovary weight increased in higher socioeconomic areas and was positively associated with hard surfaces and leaf litter at a local scale. The larger size and increased reproductive capacity of N.plumipes in urban areas show that some species benefit from the habitat changes associated with urbanisation. Our results also highlight the importance of incorporating environmental variables from multiple scales when quantifying species responses to landscape modification. PMID:25140809

  11. Web-building management in an orb-weaving spider, Zygiella x-notata: influence of prey and conspecifics.

    PubMed

    Thévenard, Laurent; Leborgne, Raymond; Pasquet, Alain

    2004-01-01

    According to optimal foraging theory, spiders should adapt their web building to environmental variations. Until now, there was no data on the influence of simultaneous information coming from different environmental factors on web building behaviour. Under laboratory conditions, we studied the behaviour of Zygiella x-notata in the presence of prey, conspecifics, or both simultaneously. There was a stimulating effect of prey, but web building was not affected by the presence of conspecifics. When spiders and prey were present simultaneously, the effect was similar to that of prey alone; it seemed that there was no interactive influence of both factors. We discussed about the use of environmental information by spiders in foraging behaviour.

  12. The influence of varied gravito-inertial fields on the cardiac response of orb-weaving spiders

    NASA Technical Reports Server (NTRS)

    Finck, A.

    1982-01-01

    The Gz transfer function was described for the orb weaving spider A. sericatus. The functional relationship between the heartrate and the intensity of G is linear in the form of: Y = a Log Gz-1 +k. The heartrate in unrestrained animals was recorded by a laser plethysmograph developed specifically for this purpose. Following a control, sample heartrate were taken postrotation between 1.001 and 1.5 Gz in 6 steps. The underlying distribution of heartrates does not appear significantly different from a Gaussian distribution. A method of varnishing the legs of the spider was developed. This was done in order to compromise the lyriform organs, especially those located on the patellae. The lyriform organ is hypothesized to serve the receptor role in the transduction of gravity related stimuli. In preliminary animals the Gz function, post varnishing of the patellae, appears to be changed in the direction of poorer discrimination. We also observed that the resting heartrate following the varnish procedure is substantially increased.

  13. Evidence from Multiple Species that Spider Silk Glue Component ASG2 is a Spidroin

    PubMed Central

    Collin, Matthew A.; Clarke, Thomas H.; Ayoub, Nadia A.; Hayashi, Cheryl Y.

    2016-01-01

    Spiders in the superfamily Araneoidea produce viscous glue from aggregate silk glands. Aggregate glue coats prey-capture threads and hampers the escape of prey from webs, thereby increasing the foraging success of spiders. cDNAs for Aggregate Spider Glue 1 (ASG1) and 2 (ASG2) have been previously described from the golden orb-weaver, Nephila clavipes, and Western black widow, Latrodectus hesperus. To further investigate aggregate glues, we assembled ASG1 and ASG2 from genomic target capture libraries constructed from three species of cob-web weavers and three species of orb-web weavers, all araneoids. We show that ASG1 is unlikely to be a glue, but rather is part of a widespread arthropod gene family, the peritrophic matrix proteins. For ASG2, we demonstrate its remarkable architectural and sequence similarities to spider silk fibroins, indicating that ASG2 is a member of the spidroin gene family. Thus, spidroins have diversified into glues in addition to task-specific, high performance fibers. PMID:26875681

  14. Evidence from Multiple Species that Spider Silk Glue Component ASG2 is a Spidroin.

    PubMed

    Collin, Matthew A; Clarke, Thomas H; Ayoub, Nadia A; Hayashi, Cheryl Y

    2016-01-01

    Spiders in the superfamily Araneoidea produce viscous glue from aggregate silk glands. Aggregate glue coats prey-capture threads and hampers the escape of prey from webs, thereby increasing the foraging success of spiders. cDNAs for Aggregate Spider Glue 1 (ASG1) and 2 (ASG2) have been previously described from the golden orb-weaver, Nephila clavipes, and Western black widow, Latrodectus hesperus. To further investigate aggregate glues, we assembled ASG1 and ASG2 from genomic target capture libraries constructed from three species of cob-web weavers and three species of orb-web weavers, all araneoids. We show that ASG1 is unlikely to be a glue, but rather is part of a widespread arthropod gene family, the peritrophic matrix proteins. For ASG2, we demonstrate its remarkable architectural and sequence similarities to spider silk fibroins, indicating that ASG2 is a member of the spidroin gene family. Thus, spidroins have diversified into glues in addition to task-specific, high performance fibers.

  15. Synthetic spider silk fibers spun from Pyriform Spidroin 2, a glue silk protein discovered in orb-weaving spider attachment discs.

    PubMed

    Geurts, Paul; Zhao, Liang; Hsia, Yang; Gnesa, Eric; Tang, Simon; Jeffery, Felicia; La Mattina, Coby; Franz, Andreas; Larkin, Leah; Vierra, Craig

    2010-12-13

    Spider attachment disc silk fibers are spun into a viscous liquid that rapidly solidifies, gluing dragline silk fibers to substrates for locomotion or web construction. Here we report the identification and artificial spinning of a novel attachment disc glue silk fibroin, Pyriform Spidroin 2 (PySp2), from the golden orb weaver Nephila clavipes . MS studies support PySp2 is a constituent of the pyriform gland that is spun into attachment discs. Analysis of the PySp2 protein architecture reveals sequence divergence relative to the other silk family members, including the cob weaver glue silk fibroin PySp1. PySp2 contains internal block repeats that consist of two subrepeat units: one dominated by Ser, Gln, and Ala and the other Pro-rich. Artificial spinning of recombinant PySp2 truncations shows that the Ser-Gln-Ala-rich subrepeat is sufficient for the assembly of polymeric subunits and subsequent fiber formation. These studies support that both orb- and cob-weaving spiders have evolved highly polar block-repeat sequences with the ability to self-assemble into fibers, suggesting a strategy to allow fiber fabrication in the liquid environment of the attachment discs. PMID:21053953

  16. On the males of the orb-weaving spiders Alpaida nigrofrenata (Simon, 1895), A. machala Levi, 1988, and A. cisneros Levi, 1988 (Araneae, Araneidae) and a new synonymy.

    PubMed

    Poeta, Maria Rita Muniz; Lise, Arno Antonio

    2015-01-01

    The araneid spider genus Alpaida O.P.-Cambridge, 1889 has, until now, 148 described species (WSC 2015). The males of A. nigrofrenata (Simon, 1895), A. machala Levi, 1988, and A. cisneros Levi, 1988 are described here for the first time. A. moka Levi, 1988, based on female specimens, is synonymized with A. xavantina Levi, 1988, based on the study of specimens of both sexes. I.L.F. de Magalhães (MACN) is thanked for reviewing an early revision of this manuscript. We also thank to M. Machado (PUCRS) for the pictures of A. moka, and M. Kolmann (University of Toronto) and A. Londoño Burbano (PUCRS) for review the English. We are grateful to G. Hormiga for helping to improve this manuscript. M.R.M. Poeta was financially supported by CAPES at PPG-Zoo, PUCRS. PMID:26623625

  17. Reconstructing web evolution and spider diversification in the molecular era.

    PubMed

    Blackledge, Todd A; Scharff, Nikolaj; Coddington, Jonathan A; Szüts, Tamas; Wenzel, John W; Hayashi, Cheryl Y; Agnarsson, Ingi

    2009-03-31

    The evolutionary diversification of spiders is attributed to spectacular innovations in silk. Spiders are unique in synthesizing many different kinds of silk, and using silk for a variety of ecological functions throughout their lives, particularly to make prey-catching webs. Here, we construct a broad higher-level phylogeny of spiders combining molecular data with traditional morphological and behavioral characters. We use this phylogeny to test the hypothesis that the spider orb web evolved only once. We then examine spider diversification in relation to different web architectures and silk use. We find strong support for a single origin of orb webs, implying a major shift in the spinning of capture silk and repeated loss or transformation of orb webs. We show that abandonment of costly cribellate capture silk correlates with the 2 major diversification events in spiders (1). Replacement of cribellate silk by aqueous silk glue may explain the greater diversity of modern orb-weaving spiders (Araneoidea) compared with cribellate orb-weaving spiders (Deinopoidea) (2). Within the "RTA clade," which is the sister group to orb-weaving spiders and contains half of all spider diversity, >90% of species richness is associated with repeated loss of cribellate silk and abandonment of prey capture webs. Accompanying cribellum loss in both groups is a release from substrate-constrained webs, whether by aerially suspended webs, or by abandoning webs altogether. These behavioral shifts in silk and web production by spiders thus likely played a key role in the dramatic evolutionary success and ecological dominance of spiders as predators of insects.

  18. Araneae Sloveniae: a national spider species checklist.

    PubMed

    Kostanjšek, Rok; Kuntner, Matjaž

    2015-01-01

    The research of the spider fauna of Slovenia dates back to the very beginning of binomial nomenclature, and has gone through more and less prolific phases with authors concentrating on taxonomy, faunistics, ecology and zoogeographic reviews. Although the body of published works is remarkable for a small nation, the faunistic data has remained too scattered for a thorough understanding of regional biotic diversity, for comparative and ecological research, and for informed conservation purposes. A national checklist is long overdue. Here, a critical review of all published records in any language is provided. The species list currently comprises 738 species, is published online at http://www.bioportal.si/katalog/araneae.php under the title Araneae Sloveniae, and will be updated in due course. This tool will fill the void in cataloguing regional spider faunas and will facilitate further araneological research in central and southern Europe. PMID:25632258

  19. Araneae Sloveniae: a national spider species checklist

    PubMed Central

    Kostanjšek, Rok; Kuntner, Matjaž

    2015-01-01

    Abstract The research of the spider fauna of Slovenia dates back to the very beginning of binomial nomenclature, and has gone through more and less prolific phases with authors concentrating on taxonomy, faunistics, ecology and zoogeographic reviews. Although the body of published works is remarkable for a small nation, the faunistic data has remained too scattered for a thorough understanding of regional biotic diversity, for comparative and ecological research, and for informed conservation purposes. A national checklist is long overdue. Here, a critical review of all published records in any language is provided. The species list currently comprises 738 species, is published online at http://www.bioportal.si/katalog/araneae.php under the title Araneae Sloveniae, and will be updated in due course. This tool will fill the void in cataloguing regional spider faunas and will facilitate further araneological research in central and southern Europe. PMID:25632258

  20. Are temperate canopy spiders tree-species specific?

    PubMed

    Mupepele, Anne-Christine; Müller, Tobias; Dittrich, Marcus; Floren, Andreas

    2014-01-01

    Arboreal spiders in deciduous and coniferous trees were investigated on their distribution and diversity. Insecticidal knock-down was used to comprehensively sample spiders from 175 trees from 2001 to 2003 in the Białowieża forest and three remote forests in Poland. We identified 140 species from 9273 adult spiders. Spider communities were distinguished between deciduous and coniferous trees. The richest fauna was collected from Quercus where beta diversity was also highest. A tree-species-specific pattern was clearly observed for Alnus, Carpinus, Picea and Pinus trees and also for those tree species that were fogged in only four or three replicates, namely Betula and Populus. This hitherto unrecognised association was mainly due to the community composition of common species identified in a Dufrene-Legendre indicator species analysis. It was not caused by spatial or temporal autocorrelation. Explaining tree-species specificity for generalist predators like spiders is difficult and has to involve physical and ecological tree parameters like linkage with the abundance of prey species. However, neither did we find a consistent correlation of prey group abundances with spiders nor could differences in spider guild composition explain the observed pattern. Our results hint towards the importance of deterministic mechanisms structuring communities of generalist canopy spiders although the casual relationship is not yet understood.

  1. Are temperate canopy spiders tree-species specific?

    PubMed

    Mupepele, Anne-Christine; Müller, Tobias; Dittrich, Marcus; Floren, Andreas

    2014-01-01

    Arboreal spiders in deciduous and coniferous trees were investigated on their distribution and diversity. Insecticidal knock-down was used to comprehensively sample spiders from 175 trees from 2001 to 2003 in the Białowieża forest and three remote forests in Poland. We identified 140 species from 9273 adult spiders. Spider communities were distinguished between deciduous and coniferous trees. The richest fauna was collected from Quercus where beta diversity was also highest. A tree-species-specific pattern was clearly observed for Alnus, Carpinus, Picea and Pinus trees and also for those tree species that were fogged in only four or three replicates, namely Betula and Populus. This hitherto unrecognised association was mainly due to the community composition of common species identified in a Dufrene-Legendre indicator species analysis. It was not caused by spatial or temporal autocorrelation. Explaining tree-species specificity for generalist predators like spiders is difficult and has to involve physical and ecological tree parameters like linkage with the abundance of prey species. However, neither did we find a consistent correlation of prey group abundances with spiders nor could differences in spider guild composition explain the observed pattern. Our results hint towards the importance of deterministic mechanisms structuring communities of generalist canopy spiders although the casual relationship is not yet understood. PMID:24586251

  2. Bat Predation by Spiders

    PubMed Central

    Nyffeler, Martin; Knörnschild, Mirjam

    2013-01-01

    In this paper more than 50 incidences of bats being captured by spiders are reviewed. Bat-catching spiders have been reported from virtually every continent with the exception of Antarctica (∼90% of the incidences occurring in the warmer areas of the globe between latitude 30° N and 30° S). Most reports refer to the Neotropics (42% of observed incidences), Asia (28.8%), and Australia-Papua New Guinea (13.5%). Bat-catching spiders belong to the mygalomorph family Theraphosidae and the araneomorph families Nephilidae, Araneidae, and Sparassidae. In addition to this, an attack attempt by a large araneomorph hunting spider of the family Pisauridae on an immature bat was witnessed. Eighty-eight percent of the reported incidences of bat catches were attributable to web-building spiders and 12% to hunting spiders. Large tropical orb-weavers of the genera Nephila and Eriophora in particular have been observed catching bats in their huge, strong orb-webs (of up to 1.5 m diameter). The majority of identifiable captured bats were small aerial insectivorous bats, belonging to the families Vespertilionidae (64%) and Emballonuridae (22%) and usually being among the most common bat species in their respective geographic area. While in some instances bats entangled in spider webs may have died of exhaustion, starvation, dehydration, and/or hyperthermia (i.e., non-predation death), there were numerous other instances where spiders were seen actively attacking, killing, and eating the captured bats (i.e., predation). This evidence suggests that spider predation on flying vertebrates is more widespread than previously assumed. PMID:23516436

  3. Bat predation by spiders.

    PubMed

    Nyffeler, Martin; Knörnschild, Mirjam

    2013-01-01

    In this paper more than 50 incidences of bats being captured by spiders are reviewed. Bat-catching spiders have been reported from virtually every continent with the exception of Antarctica (≈ 90% of the incidences occurring in the warmer areas of the globe between latitude 30° N and 30° S). Most reports refer to the Neotropics (42% of observed incidences), Asia (28.8%), and Australia-Papua New Guinea (13.5%). Bat-catching spiders belong to the mygalomorph family Theraphosidae and the araneomorph families Nephilidae, Araneidae, and Sparassidae. In addition to this, an attack attempt by a large araneomorph hunting spider of the family Pisauridae on an immature bat was witnessed. Eighty-eight percent of the reported incidences of bat catches were attributable to web-building spiders and 12% to hunting spiders. Large tropical orb-weavers of the genera Nephila and Eriophora in particular have been observed catching bats in their huge, strong orb-webs (of up to 1.5 m diameter). The majority of identifiable captured bats were small aerial insectivorous bats, belonging to the families Vespertilionidae (64%) and Emballonuridae (22%) and usually being among the most common bat species in their respective geographic area. While in some instances bats entangled in spider webs may have died of exhaustion, starvation, dehydration, and/or hyperthermia (i.e., non-predation death), there were numerous other instances where spiders were seen actively attacking, killing, and eating the captured bats (i.e., predation). This evidence suggests that spider predation on flying vertebrates is more widespread than previously assumed.

  4. Verified spider bites in Oregon (USA) with the intent to assess hobo spider venom toxicity.

    PubMed

    McKeown, Nathanael; Vetter, Richard S; Hendrickson, Robert G

    2014-06-01

    This study compiled 33 verified spider bites from the state of Oregon (USA). The initial goal was to amass a series of bites by the hobo spider to assess whether it possesses toxic venom, a supposition which is currently in a contested state. None of the 33 bites from several spider species developed significant medical symptoms nor did dermonecrosis occur. The most common biters were the yellow sac spider, Cheiracanthium mildei (N = 10) and orb-weavers of the genus Araneus (N = 6). There were 10 bites from three genera of funnel web spiders of the family Agelenidae including one hobo spider bite and one from the congeneric giant house spider which is readily confused as a hobo spider. The hobo spider bite resulted in pain, redness, twitching in the calf muscle and resolved in 12 h. Also generated from this study were possibly the first records of bites from spiders of the genera Callobius (Amaurobiidae) and Antrodiaetus (Antrodiaetidae), both with minor manifestations.

  5. Convergent evolution of behavior in an adaptive radiation of Hawaiian web-building spiders.

    PubMed

    Blackledge, Todd A; Gillespie, Rosemary G

    2004-11-16

    Species in ecologically similar habitats often display patterns of divergence that are strikingly comparable, suggesting that natural selection can lead to predictable evolutionary change in communities. However, the relative importance of selection as an agent mediating in situ diversification, versus dispersal between habitats, cannot be addressed without knowledge of phylogenetic history. We used an adaptive radiation of spiders within the Hawaiian Islands to test the prediction that species of spiders on different islands would independently evolve webs with similar architectures. Tetragnatha spiders are the only nocturnal orb-weaving spiders endemic to the Hawaiian archipelago, and multiple species of orb-weaving Tetragnatha co-occur within mesic and wet forest habitats on each of the main islands. Therefore, comparison of web architectures spun by spiders on different islands allowed study of replicated evolutionary events of past behavioral diversification. We found that species within each island construct webs with architectures that differ from one another. However, pairs of species on different islands, "ethotypes," share remarkable similarities in web architectures. Phylogenetic analysis demonstrated that the species comprising these ethotypes evolved independent of one another. Our study illustrates the high degree of predictability that can be exhibited by the evolutionary diversification of complex behaviors. However, not all web architectures were shared between islands, demonstrating that unique effects also have played an important role in the historical diversification of behavior.

  6. Reproducing Natural Spider Silks’ Copolymer Behavior in Synthetic Silk Mimics

    PubMed Central

    An, Bo; Jenkins, Janelle E.; Sampath, Sujatha; Holland, Gregory P.; Hinman, Mike; Yarger, Jeffery L.; Lewis, Randolph

    2012-01-01

    Dragline silk from orb-weaving spiders is a copolymer of two large proteins, major ampullate spidroin 1 (MaSp1) and 2 (MaSp2). The ratio of these proteins is known to have a large variation across different species of orb-weaving spiders. NMR results from gland material of two different species of spiders, N. clavipes and A. aurantia, indicates that MaSp1 proteins are more easily formed into β-sheet nanostructures, while MaSp2 proteins form random coil and helical structures. To test if this behavior of natural silk proteins could be reproduced by recombinantly produced spider silk mimic protein, recombinant MaSp1/MaSp2 mixed fibers as well as chimeric silk fibers from MaSp1 and MaSp2 sequences in a single protein were produced based on the variable ratio and conserved motifs of MaSp1 and MaSp2 in native silk fiber. Mechanical properties, solid-state NMR, and XRD results of tested synthetic fibers indicate the differing roles of MaSp1 and MaSp2 in the fiber and verify the importance of postspin stretching treatment in helping the fiber to form the proper spatial structure. PMID:23110450

  7. Reproducing natural spider silks' copolymer behavior in synthetic silk mimics.

    PubMed

    An, Bo; Jenkins, Janelle E; Sampath, Sujatha; Holland, Gregory P; Hinman, Mike; Yarger, Jeffery L; Lewis, Randolph

    2012-12-10

    Dragline silk from orb-weaving spiders is a copolymer of two large proteins, major ampullate spidroin 1 (MaSp1) and 2 (MaSp2). The ratio of these proteins is known to have a large variation across different species of orb-weaving spiders. NMR results from gland material of two different species of spiders, N. clavipes and A. aurantia , indicates that MaSp1 proteins are more easily formed into β-sheet nanostructures, while MaSp2 proteins form random coil and helical structures. To test if this behavior of natural silk proteins could be reproduced by recombinantly produced spider silk mimic protein, recombinant MaSp1/MaSp2 mixed fibers as well as chimeric silk fibers from MaSp1 and MaSp2 sequences in a single protein were produced based on the variable ratio and conserved motifs of MaSp1 and MaSp2 in native silk fiber. Mechanical properties, solid-state NMR, and XRD results of tested synthetic fibers indicate the differing roles of MaSp1 and MaSp2 in the fiber and verify the importance of postspin stretching treatment in helping the fiber to form the proper spatial structure. PMID:23110450

  8. Reproducing Natural Spider Silks' Copolymer Behavior in Synthetic Silk Mimics

    SciTech Connect

    An, Bo; Jenkins, Janelle E; Sampath, Sujatha; Holland, Gregory P; Hinman, Mike; Yarger, Jeffery L; Lewis, Randolph

    2012-10-30

    Dragline silk from orb-weaving spiders is a copolymer of two large proteins, major ampullate spidroin 1 (MaSp1) and 2 (MaSp2). The ratio of these proteins is known to have a large variation across different species of orb-weaving spiders. NMR results from gland material of two different species of spiders, N. clavipes and A. aurantia, indicates that MaSp1 proteins are more easily formed into β-sheet nanostructures, while MaSp2 proteins form random coil and helical structures. To test if this behavior of natural silk proteins could be reproduced by recombinantly produced spider silk mimic protein, recombinant MaSp1/MaSp2 mixed fibers as well as chimeric silk fibers from MaSp1 and MaSp2 sequences in a single protein were produced based on the variable ratio and conserved motifs of MaSp1 and MaSp2 in native silk fiber. Mechanical properties, solid-state NMR, and XRD results of tested synthetic fibers indicate the differing roles of MaSp1 and MaSp2 in the fiber and verify the importance of postspin stretching treatment in helping the fiber to form the proper spatial structure.

  9. Piriform Spider Silk Sequences Reveal Unique Repetitive Elements

    PubMed Central

    Perry, David J.; Bittencourt, Daniela; Siltberg-Liberles, Jessica; Rech, Elibio L.; Lewis, Randolph V.

    2010-01-01

    Orb-weaving spider silk fibers are assembled from very large, highly repetitive proteins. The repeated segments contain, in turn, short, simple repetitive amino acid motifs that account for the physical and mechanical properties of the assembled fiber. Of the six orb-weaver silk fibroins, the piriform silk that makes the attachment discs, which lashes the joints of the web and attaches dragline silk to surfaces has not been previously characterized. Piriform silk protein cDNAs were isolated from phage libraries of three species, A. trifasciata, N. clavipes, and N. cruentata. The deduced amino acid sequences from these genes revealed two new repetitive motifs: an alternating proline motif where every other amino acid is proline, and a glutamine-rich motif of 6 to 8 amino acids. Similar to other spider silk proteins, the repeated segments are large (>200 amino acids) and highly homogenized within a species. There is also substantial sequence similarity across the genes from the three species with particular conservation of the repetitive motifs. Northern blot analysis revealed that the messenger RNA is larger than 11kb and is expressed exclusively in the piriform glands of the spider. Phylogenetic analysis of the C-terminal regions of the new proteins with published spidroins robustly shows that the pirifom sequences form an ortholog group. PMID:20954740

  10. Piriform spider silk sequences reveal unique repetitive elements.

    PubMed

    Perry, David J; Bittencourt, Daniela; Siltberg-Liberles, Jessica; Rech, Elibio L; Lewis, Randolph V

    2010-11-01

    Orb-weaving spider silk fibers are assembled from very large, highly repetitive proteins. The repeated segments contain, in turn, short, simple, and repetitive amino acid motifs that account for the physical and mechanical properties of the assembled fiber. Of the six orb-weaver silk fibroins, the piriform silk that makes the attachment discs, which lashes the joints of the web and attaches dragline silk to surfaces, has not been previously characterized. Piriform silk protein cDNAs were isolated from phage libraries of three species: A. trifasciata , N. clavipes , and N. cruentata . The deduced amino acid sequences from these genes revealed two new repetitive motifs: an alternating proline motif, where every other amino acid is proline, and a glutamine-rich motif of 6-8 amino acids. Similar to other spider silk proteins, the repeated segments are large (>200 amino acids) and highly homogenized within a species. There is also substantial sequence similarity across the genes from the three species, with particular conservation of the repetitive motifs. Northern blot analysis revealed that the mRNA is larger than 11 kb and is expressed exclusively in the piriform glands of the spider. Phylogenetic analysis of the C-terminal regions of the new proteins with published spidroins robustly shows that the piriform sequences form an ortholog group.

  11. Linking Native and Invader Traits Explains Native Spider Population Responses to Plant Invasion.

    PubMed

    Smith, Jennifer N; Emlen, Douglas J; Pearson, Dean E

    2016-01-01

    Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe) stems to determine if native spiders' web-building behaviors could explain differences in spider population responses to structural changes arising from C. stoebe invasion. After two years, irregular web-spiders were >30 times more abundant and orb weavers were >23 times more abundant on simulated invasion plots compared to controls. Additionally, irregular web-spiders on simulated invasion plots built webs that were 4.4 times larger and 5.0 times more likely to capture prey, leading to >2-fold increases in recruitment. Orb-weavers showed no differences in web size or prey captures between treatments. Web-spider responses to simulated invasion mimicked patterns following natural invasions, confirming that C. stoebe's architecture is likely the primary attribute driving native spider responses to these invasions. Differences in spider responses were attributable to differences in web construction behaviors relative to historic web substrate constraints. Orb-weavers in this system constructed webs between multiple plants, so they were limited by the overall quantity of native substrates but not by the architecture of individual native plant species. Irregular web-spiders built their webs within individual plants and were greatly constrained by the diminutive architecture of native plant substrates, so they were limited both by quantity and quality of native substrates. Evaluating native species traits in the context of invader-driven change can explain invasion outcomes and help to identify factors limiting native populations. PMID:27082240

  12. Linking Native and Invader Traits Explains Native Spider Population Responses to Plant Invasion.

    PubMed

    Smith, Jennifer N; Emlen, Douglas J; Pearson, Dean E

    2016-01-01

    Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe) stems to determine if native spiders' web-building behaviors could explain differences in spider population responses to structural changes arising from C. stoebe invasion. After two years, irregular web-spiders were >30 times more abundant and orb weavers were >23 times more abundant on simulated invasion plots compared to controls. Additionally, irregular web-spiders on simulated invasion plots built webs that were 4.4 times larger and 5.0 times more likely to capture prey, leading to >2-fold increases in recruitment. Orb-weavers showed no differences in web size or prey captures between treatments. Web-spider responses to simulated invasion mimicked patterns following natural invasions, confirming that C. stoebe's architecture is likely the primary attribute driving native spider responses to these invasions. Differences in spider responses were attributable to differences in web construction behaviors relative to historic web substrate constraints. Orb-weavers in this system constructed webs between multiple plants, so they were limited by the overall quantity of native substrates but not by the architecture of individual native plant species. Irregular web-spiders built their webs within individual plants and were greatly constrained by the diminutive architecture of native plant substrates, so they were limited both by quantity and quality of native substrates. Evaluating native species traits in the context of invader-driven change can explain invasion outcomes and help to identify factors limiting native populations.

  13. Linking Native and Invader Traits Explains Native Spider Population Responses to Plant Invasion

    PubMed Central

    Emlen, Douglas J.; Pearson, Dean E.

    2016-01-01

    Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe) stems to determine if native spiders’ web-building behaviors could explain differences in spider population responses to structural changes arising from C. stoebe invasion. After two years, irregular web-spiders were >30 times more abundant and orb weavers were >23 times more abundant on simulated invasion plots compared to controls. Additionally, irregular web-spiders on simulated invasion plots built webs that were 4.4 times larger and 5.0 times more likely to capture prey, leading to >2-fold increases in recruitment. Orb-weavers showed no differences in web size or prey captures between treatments. Web-spider responses to simulated invasion mimicked patterns following natural invasions, confirming that C. stoebe’s architecture is likely the primary attribute driving native spider responses to these invasions. Differences in spider responses were attributable to differences in web construction behaviors relative to historic web substrate constraints. Orb-weavers in this system constructed webs between multiple plants, so they were limited by the overall quantity of native substrates but not by the architecture of individual native plant species. Irregular web-spiders built their webs within individual plants and were greatly constrained by the diminutive architecture of native plant substrates, so they were limited both by quantity and quality of native substrates. Evaluating native species traits in the context of invader-driven change can explain invasion outcomes and help to identify factors limiting native populations. PMID:27082240

  14. Six new species of the spider genus Spiricoelotes species (Araneae, Agelenidae) from caves in Jiangxi, China

    PubMed Central

    Chen, Lu; Zhao, Zhe; Li, Shuqiang

    2016-01-01

    Abstract Six new species of the spider genus Spiricoelotes Wang, 2002 are described, Spiricoelotes anshiensis Chen & Li, sp. n. (♂♀), Spiricoelotes chufengensis Chen & Li, sp. n. (♂♀), Spiricoelotes nansheensis Chen & Li, sp. n. (♂♀), Spiricoelotes taipingensis Chen & Li, sp. n. (♂♀), Spiricoelotes xianheensis Chen & Li, sp. n. (♂♀) and Spiricoelotes xiongxinensis Chen & Li, sp. n. (♀). All new species were collected from caves in Jiangxi Province, China. PMID:27006612

  15. Six new species of the spider genus Spiricoelotes species (Araneae, Agelenidae) from caves in Jiangxi, China.

    PubMed

    Chen, Lu; Zhao, Zhe; Li, Shuqiang

    2016-01-01

    Six new species of the spider genus Spiricoelotes Wang, 2002 are described, Spiricoelotes anshiensis Chen & Li, sp. n. (♂♀), Spiricoelotes chufengensis Chen & Li, sp. n. (♂♀), Spiricoelotes nansheensis Chen & Li, sp. n. (♂♀), Spiricoelotes taipingensis Chen & Li, sp. n. (♂♀), Spiricoelotes xianheensis Chen & Li, sp. n. (♂♀) and Spiricoelotes xiongxinensis Chen & Li, sp. n. (♀). All new species were collected from caves in Jiangxi Province, China. PMID:27006612

  16. Behavioural and biomaterial coevolution in spider orb webs.

    PubMed

    Sensenig, A; Agnarsson, I; Blackledge, T A

    2010-09-01

    Mechanical performance of biological structures, such as tendons, byssal threads, muscles, and spider webs, is determined by a complex interplay between material quality (intrinsic material properties, larger scale morphology) and proximate behaviour. Spider orb webs are a system in which fibrous biomaterials--silks--are arranged in a complex design resulting from stereotypical behavioural patterns, to produce effective energy absorbing traps for flying prey. Orb webs show an impressive range of designs, some effective at capturing tiny insects such as midges, others that can occasionally stop even small birds. Here, we test whether material quality and behaviour (web design) co-evolve to fine-tune web function. We quantify the intrinsic material properties of the sticky capture silk and radial support threads, as well as their architectural arrangement in webs, across diverse species of orb-weaving spiders to estimate the maximum potential performance of orb webs as energy absorbing traps. We find a dominant pattern of material and behavioural coevolution where evolutionary shifts to larger body sizes, a common result of fecundity selection in spiders, is repeatedly accompanied by improved web performance because of changes in both silk material and web spinning behaviours. Large spiders produce silk with improved material properties, and also use more silk, to make webs with superior stopping potential. After controlling for spider size, spiders spinning higher quality silk used it more sparsely in webs. This implies that improvements in silk quality enable 'sparser' architectural designs, or alternatively that spiders spinning lower quality silk compensate architecturally for the inferior material quality of their silk. In summary, spider silk material properties are fine-tuned to the architectures of webs across millions of years of diversification, a coevolutionary pattern not yet clearly demonstrated for other important biomaterials such as tendon, mollusc

  17. Behavioural and biomaterial coevolution in spider orb webs.

    PubMed

    Sensenig, A; Agnarsson, I; Blackledge, T A

    2010-09-01

    Mechanical performance of biological structures, such as tendons, byssal threads, muscles, and spider webs, is determined by a complex interplay between material quality (intrinsic material properties, larger scale morphology) and proximate behaviour. Spider orb webs are a system in which fibrous biomaterials--silks--are arranged in a complex design resulting from stereotypical behavioural patterns, to produce effective energy absorbing traps for flying prey. Orb webs show an impressive range of designs, some effective at capturing tiny insects such as midges, others that can occasionally stop even small birds. Here, we test whether material quality and behaviour (web design) co-evolve to fine-tune web function. We quantify the intrinsic material properties of the sticky capture silk and radial support threads, as well as their architectural arrangement in webs, across diverse species of orb-weaving spiders to estimate the maximum potential performance of orb webs as energy absorbing traps. We find a dominant pattern of material and behavioural coevolution where evolutionary shifts to larger body sizes, a common result of fecundity selection in spiders, is repeatedly accompanied by improved web performance because of changes in both silk material and web spinning behaviours. Large spiders produce silk with improved material properties, and also use more silk, to make webs with superior stopping potential. After controlling for spider size, spiders spinning higher quality silk used it more sparsely in webs. This implies that improvements in silk quality enable 'sparser' architectural designs, or alternatively that spiders spinning lower quality silk compensate architecturally for the inferior material quality of their silk. In summary, spider silk material properties are fine-tuned to the architectures of webs across millions of years of diversification, a coevolutionary pattern not yet clearly demonstrated for other important biomaterials such as tendon, mollusc

  18. Spider assemblages in the overstory, understory, and ground layers of managed stands in the western boreal mixedwood forest of Canada.

    PubMed

    Pinzon, Jaime; Spence, John R; Langor, David W

    2011-08-01

    Logging is the main human disturbance in the boreal forest; thus, understanding the effects of harvesting practices on biodiversity is essential for a more sustainable forestry. To assess changes in spider composition because of harvesting, samples were collected from three forest layers (overstory, understory, and ground) of deciduous and conifer dominated stands in the northwestern Canadian boreal mixedwood forest. Spider assemblages and feeding guild composition were compared between uncut controls and stands harvested to 20% retention. In total, 143 spider species were collected, 74 from the ground, 60 from the understory, and 71 from the overstory, and species composition of these three pools differed considerably among layers. Distinctive spider assemblages were collected from the canopy of each forest cover type but these were only slightly affected by harvesting. However, logging had a greater impact on the species composition in the understory and ground layers when compared with unharvested controls. Guild structure differed among layers, with wandering and sheet-weaving spiders dominant on the ground while orb-weaving and ambush spiders were better represented in the understory and overstory, respectively. Given the ecological importance of spiders and the expectation of faunal changes with increased harvesting, further efforts toward the understanding of species composition in higher strata of the boreal forest are needed.

  19. Quantitative analysis of orb web patterns in four species of spiders.

    PubMed

    Risch, P

    1977-05-01

    The orb webs of the four species Araneus pima (species nova), Araneus diadematus (Clerck), Argiope aurantia (Lucas), and Neoscona domiciliorum (Hentz) built under controlled laboratory conditions were compared and evaluated quantitatively at two different points in the life cycle in regard to size, regularity, shape, and fine structure. Orb webs of two species from one genus can be distinguished, but are more alike than webs from different genera. Mature spiders built highly specific webs, a fact which may play a role in species isolation during courtship. In adults, web measures correlated in size with the spiders' taxon; young spiders' web size measurements corresponded rather to their body weight or leg length. A web's regularity seemed to be closely related to age. Adult and young spiders built oval-shaped webs with eccentric hubs. Mesh width was correlated with leg length at both age levels. Web data support the likelihood of a monophyletic evolution of the four species.

  20. Early Events in the Evolution of Spider Silk Genes

    PubMed Central

    Starrett, James; Garb, Jessica E.; Kuelbs, Amanda; Azubuike, Ugochi O.; Hayashi, Cheryl Y.

    2012-01-01

    Silk spinning is essential to spider ecology and has had a key role in the expansive diversification of spiders. Silk is composed primarily of proteins called spidroins, which are encoded by a multi-gene family. Spidroins have been studied extensively in the derived clade, Orbiculariae (orb-weavers), from the suborder Araneomorphae (‘true spiders’). Orbicularians produce a suite of different silks, and underlying this repertoire is a history of duplication and spidroin gene divergence. A second class of silk proteins, Egg Case Proteins (ECPs), is known only from the orbicularian species, Lactrodectus hesperus (Western black widow). In L. hesperus, ECPs bond with tubuliform spidroins to form egg case silk fibers. Because most of the phylogenetic diversity of spiders has not been sampled for their silk genes, there is limited understanding of spidroin gene family history and the prevalence of ECPs. Silk genes have not been reported from the suborder Mesothelae (segmented spiders), which diverged from all other spiders >380 million years ago, and sampling from Mygalomorphae (tarantulas, trapdoor spiders) and basal araneomorph lineages is sparse. In comparison to orbicularians, mesotheles and mygalomorphs have a simpler silk biology and thus are hypothesized to have less diversity of silk genes. Here, we present cDNAs synthesized from the silk glands of six mygalomorph species, a mesothele, and a non-orbicularian araneomorph, and uncover a surprisingly rich silk gene diversity. In particular, we find ECP homologs in the mesothele, suggesting that ECPs were present in the common ancestor of extant spiders, and originally were not specialized to complex with tubuliform spidroins. Furthermore, gene-tree/species-tree reconciliation analysis reveals that numerous spidroin gene duplications occurred after the split between Mesothelae and Opisthothelae (Mygalomorphae plus Araneomorphae). We use the spidroin gene tree to reconstruct the evolution of amino acid compositions

  1. The scaling of safety factor in spider draglines.

    PubMed

    Ortlepp, Christine; Gosline, John M

    2008-09-01

    This study documents the effect of body mass on the size and strength of draglines produced by the orb-weaving spider Araneus diadematus and the jumping spider Salticus scenicus. Silk samples obtained from individuals spanning the range from first-instar juveniles to gravid adults were tested to determine both the properties of the silk material and the strength and static safety factor of the draglines produced by each individual spider. Analysis of material properties indicates that the tensile strength and extensibility of the silks employed by each species are identical over the entire size range of the species. Analysis of the breaking forces for individual draglines, however, indicates that the draglines scale allometrically with the spider's body mass. For Araneus, breaking force (N) scales with body mass (kg) as Fmax=11.2M0.786, and the static safety factor (S(BW)=Fmax/Mg) scales as S(BW)=1.14M(-0.214). For Salticus, Fmax=0.363M0.66 and S(BW)=0.037M(-0.34). Thus, static safety factors decrease as these spiders grow, with values falling to 4-6 for adult Araneus and to 1-2 for adult Salticus. Analysis of these results suggests that the safety lines produced by these two species are not able to absorb the impact energy of most falls with a fixed length of pre-existing silk, except in the smallest of the Araneus spiders. It is therefore likely that both spiders must draw new silk from their spinnerets during falls to keep the dynamic loads on their safety-lines below failure levels. PMID:18723542

  2. Subsocial behaviour and brood adoption in mixed-species colonies of two theridiid spiders

    NASA Astrophysics Data System (ADS)

    Grinsted, Lena; Agnarsson, Ingi; Bilde, Trine

    2012-12-01

    Cooperation and group living often evolves through kin selection. However, associations between unrelated organisms, such as different species, can evolve if both parties benefit from the interaction. Group living is rare in spiders, but occurs in cooperative, permanently social spiders, as well as in territorial, colonial spiders. Mixed species spider colonies, involving closely related species, have rarely been documented. We examined social interactions in newly discovered mixed-species colonies of theridiid spiders on Bali, Indonesia. Our aim was to test the degree of intra- and interspecific tolerance, aggression and cooperation through behavioural experiments and examine the potential for adoption of foreign brood. Morphological and genetic analyses confirmed that colonies consisted of two related species Chikunia nigra (O.P. Cambridge, 1880) new combination (previously Chrysso nigra) and a yet undescribed Chikunia sp. Females defended territories and did not engage in cooperative prey capture, but interestingly, both species seemed to provide extended maternal care of young and indiscriminate care for foreign brood. Future studies may reveal whether these species adopt only intra-specific young, or also inter-specifically. We classify both Chikunia species subsocial and intra- and interspecifically colonial, and discuss the evolutionary significance of a system where one or both species may potentially benefit from mutual tolerance and brood adoption.

  3. Adaptation of the spiders to the environment: the case of some Chilean species.

    PubMed

    Canals, Mauricio; Veloso, Claudio; Solís, Rigoberto

    2015-01-01

    Spiders are small arthropods that have colonized terrestrial environments. These impose three main problems: (i) terrestrial habitats have large fluctuations in temperature and humidity; (ii) the internal concentration of water is higher than the external environment in spiders, which exposes them continually to water loss; and (iii) their small body size determines a large surface/volume ratio, affecting energy exchange and influencing the life strategy. In this review we focus on body design, energetic, thermal selection, and water balance characteristics of some spider species present in Chile and correlate our results with ecological and behavioral information. Preferred temperatures and critical temperatures of Chilean spiders vary among species and individuals and may be adjusted by phenotypic plasticity. For example in the mygalomorph high-altitude spider Paraphysa parvula the preferred temperature is similar to that of the lowland spider Grammostola rosea; but while P. parvula shows phenotypic plasticity, G. rosea does not. The araneomorph spiders Loxosceles laeta and Scytodes globula have greater daily variations in preferred temperatures at twilight and during the night, which are set to the nocturnal activity rhythms of these species. They also present acclimation of the minimum critical temperatures. Dysdera crocata has a low preferred temperature adjusted to its favorite prey, the woodlouse. Spider metabolic rate is low compared to other arthropods, which may be associated with its sit and wait predatory strategy particularly in primitive hunter and weavers. In mygalomorph spiders the respiratory system is highly optimized with high oxygen conductance, for example G. rosea needs only a difference of 0.12-0.16 kPa in the oxygen partial pressure across the air-hemolymph barrier to satisfy its resting oxygen consumption demands. Water loss is a significant stress for spiders. Paraphysa parvula shows an evaporative water loss 10 times more than usual when

  4. Adaptation of the spiders to the environment: the case of some Chilean species

    PubMed Central

    Canals, Mauricio; Veloso, Claudio; Solís, Rigoberto

    2015-01-01

    Spiders are small arthropods that have colonized terrestrial environments. These impose three main problems: (i) terrestrial habitats have large fluctuations in temperature and humidity; (ii) the internal concentration of water is higher than the external environment in spiders, which exposes them continually to water loss; and (iii) their small body size determines a large surface/volume ratio, affecting energy exchange and influencing the life strategy. In this review we focus on body design, energetic, thermal selection, and water balance characteristics of some spider species present in Chile and correlate our results with ecological and behavioral information. Preferred temperatures and critical temperatures of Chilean spiders vary among species and individuals and may be adjusted by phenotypic plasticity. For example in the mygalomorph high-altitude spider Paraphysa parvula the preferred temperature is similar to that of the lowland spider Grammostola rosea; but while P. parvula shows phenotypic plasticity, G. rosea does not. The araneomorph spiders Loxosceles laeta and Scytodes globula have greater daily variations in preferred temperatures at twilight and during the night, which are set to the nocturnal activity rhythms of these species. They also present acclimation of the minimum critical temperatures. Dysdera crocata has a low preferred temperature adjusted to its favorite prey, the woodlouse. Spider metabolic rate is low compared to other arthropods, which may be associated with its sit and wait predatory strategy particularly in primitive hunter and weavers. In mygalomorph spiders the respiratory system is highly optimized with high oxygen conductance, for example G. rosea needs only a difference of 0.12–0.16 kPa in the oxygen partial pressure across the air-hemolymph barrier to satisfy its resting oxygen consumption demands. Water loss is a significant stress for spiders. Paraphysa parvula shows an evaporative water loss 10 times more than usual

  5. Adaptation of the spiders to the environment: the case of some Chilean species.

    PubMed

    Canals, Mauricio; Veloso, Claudio; Solís, Rigoberto

    2015-01-01

    Spiders are small arthropods that have colonized terrestrial environments. These impose three main problems: (i) terrestrial habitats have large fluctuations in temperature and humidity; (ii) the internal concentration of water is higher than the external environment in spiders, which exposes them continually to water loss; and (iii) their small body size determines a large surface/volume ratio, affecting energy exchange and influencing the life strategy. In this review we focus on body design, energetic, thermal selection, and water balance characteristics of some spider species present in Chile and correlate our results with ecological and behavioral information. Preferred temperatures and critical temperatures of Chilean spiders vary among species and individuals and may be adjusted by phenotypic plasticity. For example in the mygalomorph high-altitude spider Paraphysa parvula the preferred temperature is similar to that of the lowland spider Grammostola rosea; but while P. parvula shows phenotypic plasticity, G. rosea does not. The araneomorph spiders Loxosceles laeta and Scytodes globula have greater daily variations in preferred temperatures at twilight and during the night, which are set to the nocturnal activity rhythms of these species. They also present acclimation of the minimum critical temperatures. Dysdera crocata has a low preferred temperature adjusted to its favorite prey, the woodlouse. Spider metabolic rate is low compared to other arthropods, which may be associated with its sit and wait predatory strategy particularly in primitive hunter and weavers. In mygalomorph spiders the respiratory system is highly optimized with high oxygen conductance, for example G. rosea needs only a difference of 0.12-0.16 kPa in the oxygen partial pressure across the air-hemolymph barrier to satisfy its resting oxygen consumption demands. Water loss is a significant stress for spiders. Paraphysa parvula shows an evaporative water loss 10 times more than usual when

  6. Local and Landscape Correlates of Spider Activity Density and Species Richness in Urban Gardens.

    PubMed

    Otoshi, Michelle D; Bichier, Peter; Philpott, Stacy M

    2015-08-01

    Urbanization is a major threat to arthropod biodiversity and abundance due to reduction and loss of suitable natural habitat. Green spaces and small-scale agricultural areas may provide habitat and resources for arthropods within densely developed cities. We studied spider activity density (a measure of both abundance and degree of movement) and diversity in urban gardens in Santa Cruz, Santa Clara, and Monterey counties in central California, USA. We sampled for spiders with pitfall traps and sampled 38 local site characteristics for 5 mo in 19 garden sites to determine the relative importance of individual local factors. We also analyzed 16 landscape variables at 500-m and 1-km buffers surrounding each garden to determine the significance of landscape factors. We identified individuals from the most common families to species and identified individuals from other families to morphospecies. Species from the families Lycosidae and Gnaphosidae composed 81% of total adult spider individuals. Most of the significant factors that correlated with spider activity density and richness were local rather than landscape factors. Spider activity density and richness increased with mulch cover and flowering plant species, and decreased with bare soil. Thus, changes in local garden management have the potential to promote diversity of functionally important spiders in urban environments. PMID:26314049

  7. Local and Landscape Correlates of Spider Activity Density and Species Richness in Urban Gardens.

    PubMed

    Otoshi, Michelle D; Bichier, Peter; Philpott, Stacy M

    2015-08-01

    Urbanization is a major threat to arthropod biodiversity and abundance due to reduction and loss of suitable natural habitat. Green spaces and small-scale agricultural areas may provide habitat and resources for arthropods within densely developed cities. We studied spider activity density (a measure of both abundance and degree of movement) and diversity in urban gardens in Santa Cruz, Santa Clara, and Monterey counties in central California, USA. We sampled for spiders with pitfall traps and sampled 38 local site characteristics for 5 mo in 19 garden sites to determine the relative importance of individual local factors. We also analyzed 16 landscape variables at 500-m and 1-km buffers surrounding each garden to determine the significance of landscape factors. We identified individuals from the most common families to species and identified individuals from other families to morphospecies. Species from the families Lycosidae and Gnaphosidae composed 81% of total adult spider individuals. Most of the significant factors that correlated with spider activity density and richness were local rather than landscape factors. Spider activity density and richness increased with mulch cover and flowering plant species, and decreased with bare soil. Thus, changes in local garden management have the potential to promote diversity of functionally important spiders in urban environments.

  8. A new troglobitic species of the spider genus Tengella Dahl (Araneae, Tengellidae) from Chiapas, Mexico.

    PubMed

    Candia-Ramírez, Daniela T; Valdez-Mondragón, Alejandro

    2014-01-01

    A new species of troglobitic spider of the genus Tengella Dahl is described from Mexico: Tengella kalebi new species, from a limestone cave in Chiapas, Mexico. The species is described on the basis of adult male and females. This is the fifth species described for the genus Tengella, the third species described from Mexico, the first species that has notable troglomorphic modifications, and the first ecribellate Tengella species. PMID:24870640

  9. Production And Characterization Of Synthetic Spider Silks Based On Nephila Clavipes Major Ampullate Silk Proteins

    NASA Astrophysics Data System (ADS)

    An, Bo

    The extraordinary mechanical properties of orb-weaving spider silks have served spiders for over 400 million years. However, only in the late 20th century did we start to understand the molecular nature of spider silk that contributes to its incredible properties as biomaterials. Among all seven types of spider silks, major ampullate silk from typical orb-weaving spiders is the toughest of all, it consists of primarily two proteins: MaSp1 and MaSp2. Variable ratios and conserved motifs of these two proteins in all the native spider silks demonstrate the significant role of MaSp1 and MaSp2 in controlling the mechanical properties of the fiber. The amino acid sequences of the orb weaving spider silk proteins have remained almost unchanged for more than 100 million years. Interestingly, MaSp1 and MaSp2 are the only two components in all studied dragline silk fibers from these spiders. The mechanical properties of native dragline silk vary slightly between species, which are believed to relate to the ratio of MaSp1 to MaSp2 in the silk. Both of these facts clearly indicate the importance of these two proteins to the mechanical properties of the fiber. Various types of synthetic spider silk fibers have been produced and studied in an effort to mass-produce man-made fibers with qualities comparable to native spider silk. To investigate the roles of MaSp1 and MaSp2 in silk fiber, synthetic MaSp1 (major abundant protein in Nephila clavipes major ampullate silks) only fibers, MaSp1/MaSp2 protein mixture fibers and chimeric protein fibers with both MaSp1 and MaSp2 sequence features have been produced and tested for mechanical properties. Solid-State Nuclear Magnetic Resonance was used to characterize the structure of silk fibers and reveal the relation between fiber spatial structure and mechanical properties.

  10. Investigating the influence of geospatial attributes on spider species richness and diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The maintenance of biodiversity is an important aspect of the long-term sustainability of agricultural production. Maintaining biodiversity, especially in regards to predator species, promotes natural pest control and many other ecosystem services. Spiders (Araneae) often prey upon common pest speci...

  11. Ninetis russellsmithi n. sp., an unusual new pholcid spider species from Malawi (Araneae: Pholcidae).

    PubMed

    Huber, Bernhard A

    2002-01-01

    A new species Ninetis russellsmithi n. sp. is described from Malawi. It lacks the most prominent autapomorphy of pholcid spiders, the retrolateral projection of the cymbium (procursus). Biogeographically this species marks the first record for the genus in a 3000 km gap between its African congeners in Namibia and Tanzania.

  12. On the spider genus Arboricaria with the description of a new species (Araneae, Gnaphosidae)

    PubMed Central

    Mikhailov, Kirill G.

    2016-01-01

    Abstract The spider genus Arboricaria Bosmans, 2000 is redefined and an updated diagnosis given. The differences between Arboricaria and Micaria Westring, 1851 are discussed in detail. A key to all five species of the genus is provided. One new species, Arboricaria zonsteini sp. n. (♂♀), is described based on specimens from Kyrgyzstan and Azerbaijan. One new synonym is proposed: Arboricaria koeni Bosmans in Bosmans & Blick, 2000, syn. n. is assigned to Arboricaria sociabilis Kulczyński in Chyzer & Kulczyński, 1897. Data on the distribution of Arboricaria in Russia and adjacent countries are presented with references to the papers on local spider faunas. PMID:27006601

  13. On the spider genus Arboricaria with the description of a new species (Araneae, Gnaphosidae).

    PubMed

    Mikhailov, Kirill G

    2016-01-01

    The spider genus Arboricaria Bosmans, 2000 is redefined and an updated diagnosis given. The differences between Arboricaria and Micaria Westring, 1851 are discussed in detail. A key to all five species of the genus is provided. One new species, Arboricaria zonsteini sp. n. (♂♀), is described based on specimens from Kyrgyzstan and Azerbaijan. One new synonym is proposed: Arboricaria koeni Bosmans in Bosmans & Blick, 2000, syn. n. is assigned to Arboricaria sociabilis Kulczyński in Chyzer & Kulczyński, 1897. Data on the distribution of Arboricaria in Russia and adjacent countries are presented with references to the papers on local spider faunas.

  14. A new species of the spider genus Plator (Trochanteriidae) from south China.

    PubMed

    Lin, Ye-Jie; Zhu, Guang-Xiang

    2016-01-01

    The spider genus Plator Simon (1880) is a small and little-known group in the spider family Trochanteriidae. Species of Plator are called flat-spiders in Chinese for the extremely flat habitus (Zhu & Wang 1963). Up to now, 11 Plator species have been recorded from India, China, Korea and Japan. Six of them, P. insolens Simon (1880), P. pandeae Tikader (1969), P. pennatus Platnick (1976), P. sinicus Zhu & Wang (1963), P. yunlong Zhu et al. (2006) and P. bowo Zhu et al. (2006) are reported from China (World Spider Catalog 2016). Zhu et al. (2006) suggested two species groups for at least all Chinese Plator species, the P. insolens group and the P. pennatus group. The former can be recognized by the absence of RTA of male pedipalp, and the narrow first windings of the copulatory duct system of female epigyne and the latter, distinguished by the presence of RTA and the broad first windings of the copulatory duct system. PMID:27615967

  15. How Did the Spider Cross the River? Behavioral Adaptations for River-Bridging Webs in Caerostris darwini (Araneae: Araneidae)

    PubMed Central

    Gregorič, Matjaž; Agnarsson, Ingi; Blackledge, Todd A.; Kuntner, Matjaž

    2011-01-01

    Background Interspecific coevolution is well described, but we know significantly less about how multiple traits coevolve within a species, particularly between behavioral traits and biomechanical properties of animals' “extended phenotypes”. In orb weaving spiders, coevolution of spider behavior with ecological and physical traits of their webs is expected. Darwin's bark spider (Caerostris darwini) bridges large water bodies, building the largest known orb webs utilizing the toughest known silk. Here, we examine C. darwini web building behaviors to establish how bridge lines are formed over water. We also test the prediction that this spider's unique web ecology and architecture coevolved with new web building behaviors. Methodology We observed C. darwini in its natural habitat and filmed web building. We observed 90 web building events, and compared web building behaviors to other species of orb web spiders. Conclusions Caerostris darwini uses a unique set of behaviors, some unknown in other spiders, to construct its enormous webs. First, the spiders release unusually large amounts of bridging silk into the air, which is then carried downwind, across the water body, establishing bridge lines. Second, the spiders perform almost no web site exploration. Third, they construct the orb capture area below the initial bridge line. In contrast to all known orb-weavers, the web hub is therefore not part of the initial bridge line but is instead built de novo. Fourth, the orb contains two types of radial threads, with those in the upper half of the web doubled. These unique behaviors result in a giant, yet rather simplified web. Our results continue to build evidence for the coevolution of behavioral (web building), ecological (web microhabitat) and biomaterial (silk biomechanics) traits that combined allow C. darwini to occupy a unique niche among spiders. PMID:22046378

  16. Analysis of transcriptomes of three orb-web spider species reveals gene profiles involved in silk and toxin.

    PubMed

    Zhao, Ying-Jun; Zeng, Yan; Chen, Lei; Dong, Yang; Wang, Wen

    2014-12-01

    As an ancient arthropod with a history of 390 million years, spiders evolved numerous morphological forms resulting from adaptation to different environments. The venom and silk of spiders, which have promising commercial applications in agriculture, medicine and engineering fields, are of special interests to researchers. However, little is known about their genomic components, which hinders not only understanding spider biology but also utilizing their valuable genes. Here we report on deep sequenced and de novo assembled transcriptomes of three orb-web spider species, Gasteracantha arcuata, Nasoonaria sinensis and Gasteracantha hasselti which are distributed in tropical forests of south China. With Illumina paired-end RNA-seq technology, 54 871, 101 855 and 75 455 unigenes for the three spider species were obtained, respectively, among which 9 300, 10 001 and 10 494 unique genes are annotated, respectively. From these annotated unigenes, we comprehensively analyzed silk and toxin gene components and structures for the three spider species. Our study provides valuable transcriptome data for three spider species which previously lacked any genetic/genomic data. The results have laid the first fundamental genomic basis for exploiting gene resources from these spiders.

  17. Spider Diversity on the Oceanic Island of Fernando De Noronha, Brazil, and Implications for Species Conservation

    PubMed Central

    Freitas, Gilson Carlos da Conceição; Brescovit, Antonio Domingos; Vasconceloslc, Simao Dias

    2013-01-01

    Fernando de Noronha is an oceanic archipelago in Brazil that has been subjected to major alterations in its natural habitat, as it is exposed to increasing rates of tourism. This research aimed at performing the first survey of spider species on the main island, focusing on the environmental occupation and conservation status of local species. Spiders were sampled through pitfall traps, beating sheets, and active collection in the dry (October 2005) and rainy (April 2006) seasons in several parts of the island, such as urban and protected areas. A total of 1,532 adult spiders from 44 species distributed in 20 families were collected. Forty-two species are newly recorded on the archipelago, of which 10 appear to be native. Theridiidae and Salticidae were the richest families, with seven and five species respectively. Hogna sp., probably an endemic Lycosidae species, had the highest abundance throughout the study (17%). Several non-native species were found, especially in the surroundings of human habitations. Areas exposed to human settlements had higher diversity indices and evenness values when compared to preserved areas. Most species were classified as being diurnal space web-weavers. The results suggest that non-native species seemed to be established on the island, due mainly to the traffic of people and goods from the continent.

  18. Five new species of the Afrotropical dark sac spider genus Messapus Simon, 1898 (Araneae: Corinnidae).

    PubMed

    Haddad, Charles R; Mbo, Zingisile

    2015-12-11

    The Afrotropical dark sac spider genus Messapus Simon, 1898 (Corinnidae: Corinninae) currently only comprises two described species, the type species M. martini Simon, 1898 and M. natalis (Pocock, 1898), which have both recently been redescribed. The leg and setal morphology of Messapus is studied using scanning electron microscopy for the first time, for M. martini and M. tigris sp. n., and additional characters are provided to supplement a recent generic description. Five new species are described in the current paper: M. megae sp. n. (♂ ♀, from Zimbabwe), M. meridionalis sp. n. (♀, from South Africa), M. seiugatus sp. n. (♀, from Guinea), M. tigris sp. n. (♀, from Botswana and Namibia), and M. tropicus sp. n. (♂ ♀, from Democratic Republic of the Congo). All five species are arboreal spiders occurring on bark, lower foliage strata and the canopies of forest and savannah trees. An identification key to the seven species of the genus is provided.

  19. Molecular nanosprings in spider capture-silk threads

    NASA Astrophysics Data System (ADS)

    Becker, Nathan; Oroudjev, Emin; Mutz, Stephanie; Cleveland, Jason P.; Hansma, Paul K.; Hayashi, Cheryl Y.; Makarov, Dmitrii E.; Hansma, Helen G.

    2003-04-01

    Spider capture silk is a natural material that outperforms almost any synthetic material in its combination of strength and elasticity. The structure of this remarkable material is still largely unknown, because spider-silk proteins have not been crystallized. Capture silk is the sticky spiral in the webs of orb-weaving spiders. Here we are investigating specifically the capture spiral threads from Araneus, an ecribellate orb-weaving spider. The major protein of these threads is flagelliform protein, a variety of silk fibroin. We present models for molecular and supramolecular structures of flagelliform protein, derived from amino acid sequences, force spectroscopy (molecular pulling) and stretching of bulk capture web. Pulling on molecules in capture-silk fibres from Araneus has revealed rupture peaks due to sacrificial bonds, characteristic of other self-healing biomaterials. The overall force changes are exponential for both capture-silk molecules and intact strands of capture silk.

  20. Turnover of Species and Guilds in Shrub Spider Communities in a 100-Year Postlogging Forest Chronosequence.

    PubMed

    Haraguchi, Takashi F; Tayasu, Ichiro

    2016-02-01

    Disturbance of forests by logging and subsequent forest succession causes marked changes in arthropod communities. Although vegetation cover provides important habitat for arthropods, studies of the changes in their community structure associated with forest succession have been conducted mostly at ground level. To evaluate how forests of different ages contribute to arthropod biodiversity in shrub habitat, spiders were collected from shrubs in 12 forests ranging in age from 1 to 107 yr after logging. We found marked changes in spider community structure about 10 yr after logging: the number of species and individuals declined rapidly after this time. These changes were likely caused by a decrease in shrub cover in association with forest succession. Changes in spider species composition associated with stand age were small in forests at least 11 yr old and were not clustered by forest age. After the exclusion of species of which we sampled only one or two individuals incidentally, just 0.9 ± 0.5 (mean ± SD) species were unique to these older forests. The other 41.2 ± 4.3 species found in these forests were common to both older and young forests, although some of these species in common were found mainly in forests at least 11 yr old. These results suggest that preservation of old-growth forests contributes to the abundance of these common species, although old-growth forests contribute little to species diversity.

  1. Phylogenomics resolves a spider backbone phylogeny and rejects a prevailing paradigm for orb web evolution.

    PubMed

    Bond, Jason E; Garrison, Nicole L; Hamilton, Chris A; Godwin, Rebecca L; Hedin, Marshal; Agnarsson, Ingi

    2014-08-01

    Spiders represent an ancient predatory lineage known for their extraordinary biomaterials, including venoms and silks. These adaptations make spiders key arthropod predators in most terrestrial ecosystems. Despite ecological, biomedical, and biomaterial importance, relationships among major spider lineages remain unresolved or poorly supported. Current working hypotheses for a spider "backbone" phylogeny are largely based on morphological evidence, as most molecular markers currently employed are generally inadequate for resolving deeper-level relationships. We present here a phylogenomic analysis of spiders including taxa representing all major spider lineages. Our robust phylogenetic hypothesis recovers some fundamental and uncontroversial spider clades, but rejects the prevailing paradigm of a monophyletic Orbiculariae, the most diverse lineage, containing orb-weaving spiders. Based on our results, the orb web either evolved much earlier than previously hypothesized and is ancestral for a majority of spiders or else it has multiple independent origins, as hypothesized by precladistic authors. Cribellate deinopoid orb weavers that use mechanically adhesive silk are more closely related to a diverse clade of mostly webless spiders than to the araneoid orb-weaving spiders that use adhesive droplet silks. The fundamental shift in our understanding of spider phylogeny proposed here has broad implications for interpreting the evolution of spiders, their remarkable biomaterials, and a key extended phenotype--the spider web.

  2. A verified spider bite and a review of the literature confirm Indian ornamental tree spiders (Poecilotheria species) as underestimated theraphosids of medical importance.

    PubMed

    Fuchs, Joan; von Dechend, Margot; Mordasini, Raffaella; Ceschi, Alessandro; Nentwig, Wolfgang

    2014-01-01

    Literature on bird spider or tarantula bites (Theraphosidae) is rare. This is astonishing as they are coveted pets and interaction with their keepers (feeding, cleaning the terrarium or taking them out to hold) might increase the possibility for bites. Yet, this seems to be a rare event and might be why most theraphosids are considered to be harmless, even though the urticating hairs of many American species can cause disagreeable allergic reactions. We are describing a case of a verified bite by an Indian ornamental tree spider (Poecilotheria regalis), where the patient developed severe, long lasting muscle cramps several hours after the bite. We present a comprehensive review of the literature on bites of these beautiful spiders and conclude that a delayed onset of severe muscle cramps, lasting for days, is characteristic for Poecilotheria bites. We discuss Poecilotheria species as an exception from the general assumption that theraphosid bites are harmless to humans. PMID:24215987

  3. A verified spider bite and a review of the literature confirm Indian ornamental tree spiders (Poecilotheria species) as underestimated theraphosids of medical importance.

    PubMed

    Fuchs, Joan; von Dechend, Margot; Mordasini, Raffaella; Ceschi, Alessandro; Nentwig, Wolfgang

    2014-01-01

    Literature on bird spider or tarantula bites (Theraphosidae) is rare. This is astonishing as they are coveted pets and interaction with their keepers (feeding, cleaning the terrarium or taking them out to hold) might increase the possibility for bites. Yet, this seems to be a rare event and might be why most theraphosids are considered to be harmless, even though the urticating hairs of many American species can cause disagreeable allergic reactions. We are describing a case of a verified bite by an Indian ornamental tree spider (Poecilotheria regalis), where the patient developed severe, long lasting muscle cramps several hours after the bite. We present a comprehensive review of the literature on bites of these beautiful spiders and conclude that a delayed onset of severe muscle cramps, lasting for days, is characteristic for Poecilotheria bites. We discuss Poecilotheria species as an exception from the general assumption that theraphosid bites are harmless to humans.

  4. Two Trichosporon species isolated from Central-European mygalomorph spiders (Araneae: Mygalomorphae).

    PubMed

    Heneberg, Petr; Řezáč, Milan

    2013-04-01

    Trichosporon (Dikarya: Basidiomycota) is a genus of anamorphic yeasts typically associated with soil and water, although many species are causative agents of diseases in animals and man. Here we provide the first compelling evidence that spiders can be occasionally colonized by at least two Trichosporon species. Trichosporon dulcitum (Berkhout) Weijman 1979 was isolated from the exoskeleton of purse-web spider Atypus piceus, while Trichosporon porosum (Stautz) Middelhoven, Scorzetti & Fell 2001 was isolated from the exoskeleton of purse-web spider Atypus affinis. Both of the species were identified based on DNA sequence analysis of the host specimens displaying macroscopic signs of the superficial white mycosis on their exoskeleton. Only two specimens with macroscopic signs of superficial yeast growth were identified among the 125 individuals of A. affinis, A. piceus and Atypus muralis examined that were collected at various sites throughout the Czech Republic. The consistent burrow microclimate, uninterrupted occupancy of the single burrow for several subsequent years, and presence of prey remnants in the burrow below the purse-web may play a role in the course of infection of the mygalomorphs examined. The phylogenetic relationships of Trichosporon species are analyzed, concluding that association with invertebrates clusters predominantly among four groups of closely related species in independent Trichosporon clades.

  5. A new spider species, Heser stoevi sp. nov., from Turkmenistan (Araneae: Gnaphosidae)

    PubMed Central

    2016-01-01

    Abstract Background The genus Heser (Araneae, Gnaphosidae) belongs to the Zelotes group, and is currently known to comprise 10 species distributed in Africa, Asia, Europe and North America. The type species is Heser malefactor Tuneva, 2004 from Kazakhstan. New information A new spider species, Heser stoevi sp. nov. (male and female) found in Koytendag Mountains, southeastern Turkmenistan is described and illustrated. It is morphologically close to H. aradensis (Levy, 1998) from Israel but can be readily distinguished by the longer embolus, the smaller and flattened conductor, the lack of retrolateral tibial apophysis, all this coupled with very distinctive female copulatory organs. The new species was found under stones in arid grassland habitats.

  6. The Peacock Spiders (Araneae: Salticidae: Maratus) of the Queensland Museum, including six new species.

    PubMed

    Baehr, Barbara C; Whyte, Robert

    2016-01-01

    Six new species of the peacock spider genus Maratus Karsch, 1878 are described from Australia: M. eliasi sp. nov., M. julianneae sp. nov., M. licunxini sp. nov., M. michaelorum sp. nov. and M. ottoi sp. nov. from Queensland, and M. kiwirrkurra sp. nov. from Western  Australia. Five species groups are further documented within the genus and new records, detailed SEM and automontage images are provided for six previously described species: M. anomalus Karsch, 1878, M. chrysomelas (Simon, 1909), M. digitatus Otto & Hill, 2012, M. pavonis (Dunn, 1947), M. speciosus (O.P.-Cambridge, 1874) and M. volans (O.P.-Cambridge, 1874). PMID:27615856

  7. Social spiders of the genus Anelosimus occur in wetter, more productive environments than non-social species

    NASA Astrophysics Data System (ADS)

    Majer, Marija; Agnarsson, Ingi; Svenning, Jens-Christian; Bilde, Trine

    2013-11-01

    Latitude, rainfall, and productivity have been shown to influence social organisation and level of sociality in arthropods on large geographic scales. Social spiders form permanent group-living societies where they cooperate in brood care, web maintenance, and foraging. Sociality has evolved independently in a number of unrelated spider genera and may reflect convergent evolutionary responses to common environmental drivers. The genus Anelosimus contains a third of approximately 25 described permanently social spider species, eight to nine species that all occur in the Americas. To test for environmental correlates of sociality in Anelosimus across the Americas, we used logistic regression to detect effects of annual rainfall, productivity, and precipitation seasonality on the relative likelihood of occurrence of social and non-social Anelosimus spiders. Our analyses show that social species tend to occur at higher annual rainfall and productivity than non-social species, supporting the hypothesised effects of these environmental variables on the geographical distribution of social species. We did not find support for the hypothesis that permanently social species occur in areas with low precipitation seasonality. High annual precipitation and, to less extent, high productivity favour the occurrence of permanently group-living Anelosimus spiders relative to subsocial and solitary species. These results are partially consistent with previous findings for the Old World spider genus Stegodyphus, where a link between high habitat productivity and sociality was also found. Unlike Anelosimus, however, Stegodyphus typically occur in dry habitats negating a general importance of high precipitation for sociality. Sociality in spiders thus seems to be strongly linked to productivity, probably reflecting the need for relatively high availability of large prey to sustain social colonies.

  8. Chronic exposure to soil salinity in terrestrial species: Does plasticity and underlying physiology differ among specialized ground-dwelling spiders?

    PubMed

    Renault, D; Puzin, C; Foucreau, N; Bouchereau, A; Pétillon, J

    2016-07-01

    In salt marshes, the alternation of low and high tides entails rapid shifts of submersion and aerial exposure for terrestrial communities. In these intertidal environments, terrestrial species have to deal with an osmotic loss in body water content and an increase in sodium chloride concentration when salt load increases. In salt marshes, spiders represent an abundant arthropod group, whose physiological ecology in response to variations of soil salinity must be further investigated. In this study, we compared the effect of salinity on the survival and physiology of three species of Lycosidae; two salt marsh species (Arctosa fulvolineata and Pardosa purbeckensis) and one forest species (P. saltans). Spiders were individually exposed at three salinity conditions (0‰, 35‰ and 70‰) and survival, changes in body water content, hemolymph ions (Na(+), Ca(2+), Mg(2+), K(+); ICP-MS technique) and metabolites (mainly amino acids, polyols, sugars; LC and GC techniques) were assessed. The survival of the forest species P. saltans was very quickly hampered at moderate and high salinities. In this spider, variations of hemolymph ions and metabolites revealed a quick loss of physiological homeostasis and a rapid salt-induced dehydration of the specimens. Conversely, high survival durations were measured in the two salt-marsh spiders, and more particularly in A. fulvolineata. In both P. purbeckensis and A. fulvolineata, the proportion of Na(+), Ca(2+), Mg(2+), K(+) remained constant at the three experimental conditions. Accumulation of hemolymph Na(+) and amino acids (mainly glutamine and proline) demonstrated stronger osmoregulatory capacities in these salt-marsh resident spiders. To conclude, even if phylogenetically close (belonging to the same, monophyletic, family), we found different physiological capacities to cope with salt load among the three tested spider species. Nevertheless, physiological responses to salinity were highly consistent with the realized

  9. Spider orb webs rely on radial threads to absorb prey kinetic energy.

    PubMed

    Sensenig, Andrew T; Lorentz, Kimberly A; Kelly, Sean P; Blackledge, Todd A

    2012-08-01

    The kinetic energy of flying insect prey is a formidable challenge for orb-weaving spiders. These spiders construct two-dimensional, round webs from a combination of stiff, strong radial silk and highly elastic, glue-coated capture spirals. Orb webs must first stop the flight of insect prey and then retain those insects long enough to be subdued by the spiders. Consequently, spider silks rank among the toughest known biomaterials. The large number of silk threads composing a web suggests that aerodynamic dissipation may also play an important role in stopping prey. Here, we quantify energy dissipation in orb webs spun by diverse species of spiders using data derived from high-speed videos of web deformation under prey impact. By integrating video data with material testing of silks, we compare the relative contributions of radial silk, the capture spiral and aerodynamic dissipation. Radial silk dominated energy absorption in all webs, with the potential to account for approximately 100 per cent of the work of stopping prey in larger webs. The most generous estimates for the roles of capture spirals and aerodynamic dissipation show that they rarely contribute more than 30 per cent and 10 per cent of the total work of stopping prey, respectively, and then only for smaller orb webs. The reliance of spider orb webs upon internal energy absorption by radial threads for prey capture suggests that the material properties of the capture spirals are largely unconstrained by the selective pressures of stopping prey and can instead evolve freely in response to alternative functional constraints such as adhering to prey.

  10. Spider orb webs rely on radial threads to absorb prey kinetic energy

    PubMed Central

    Sensenig, Andrew T.; Lorentz, Kimberly A.; Kelly, Sean P.; Blackledge, Todd A.

    2012-01-01

    The kinetic energy of flying insect prey is a formidable challenge for orb-weaving spiders. These spiders construct two-dimensional, round webs from a combination of stiff, strong radial silk and highly elastic, glue-coated capture spirals. Orb webs must first stop the flight of insect prey and then retain those insects long enough to be subdued by the spiders. Consequently, spider silks rank among the toughest known biomaterials. The large number of silk threads composing a web suggests that aerodynamic dissipation may also play an important role in stopping prey. Here, we quantify energy dissipation in orb webs spun by diverse species of spiders using data derived from high-speed videos of web deformation under prey impact. By integrating video data with material testing of silks, we compare the relative contributions of radial silk, the capture spiral and aerodynamic dissipation. Radial silk dominated energy absorption in all webs, with the potential to account for approximately 100 per cent of the work of stopping prey in larger webs. The most generous estimates for the roles of capture spirals and aerodynamic dissipation show that they rarely contribute more than 30 per cent and 10 per cent of the total work of stopping prey, respectively, and then only for smaller orb webs. The reliance of spider orb webs upon internal energy absorption by radial threads for prey capture suggests that the material properties of the capture spirals are largely unconstrained by the selective pressures of stopping prey and can instead evolve freely in response to alternative functional constraints such as adhering to prey. PMID:22431738

  11. Alpine endemic spiders shed light on the origin and evolution of subterranean species.

    PubMed

    Mammola, Stefano; Isaia, Marco; Arnedo, Miquel A

    2015-01-01

    We designed a comparative study to unravel the phylogeography of two Alpine endemic spiders characterized by a different degree of adaptation to subterranean life: Troglohyphantes vignai (Araneae, Linyphiidae) and Pimoa rupicola (Araneae, Pimoidae), the latter showing minor adaptation to hypogean life. We sampled populations of the model species in caves and other subterranean habitats across their known geographical range in the Western Alps. By combining phylogeographic inferences and Ecological Niche Modeling techniques, we inferred the biogeographic scenario that led to the present day population structure of the two species. According to our divergent time estimates and relative uncertainties, the isolation of T. vignai and P. rupicola from their northern sister groups was tracked back to Middle-Late Miocene. Furthermore, the fingerprint left by Pleistocene glaciations on the population structure revealed by the genetic data, led to the hypothesis that a progressive adaptation to subterranean habitats occurred in T. vignai, followed by strong population isolation. On the other hand, P. rupicola underwent a remarkable genetic bottleneck during the Pleistocene glaciations, that shaped its present population structure. It seems likely that such shallow population structure is both the result of the minor degree of specialization to hypogean life and the higher dispersal ability characterizing this species. The simultaneous study of overlapping spider species showing different levels of adaptation to hypogean life, disclosed a new way to clarify patterns of biological diversification and to understand the effects of past climatic shift on the subterranean biodiversity. PMID:26734503

  12. Alpine endemic spiders shed light on the origin and evolution of subterranean species

    PubMed Central

    Mammola, Stefano; Arnedo, Miquel A.

    2015-01-01

    We designed a comparative study to unravel the phylogeography of two Alpine endemic spiders characterized by a different degree of adaptation to subterranean life: Troglohyphantes vignai (Araneae, Linyphiidae) and Pimoa rupicola (Araneae, Pimoidae), the latter showing minor adaptation to hypogean life. We sampled populations of the model species in caves and other subterranean habitats across their known geographical range in the Western Alps. By combining phylogeographic inferences and Ecological Niche Modeling techniques, we inferred the biogeographic scenario that led to the present day population structure of the two species. According to our divergent time estimates and relative uncertainties, the isolation of T. vignai and P. rupicola from their northern sister groups was tracked back to Middle–Late Miocene. Furthermore, the fingerprint left by Pleistocene glaciations on the population structure revealed by the genetic data, led to the hypothesis that a progressive adaptation to subterranean habitats occurred in T. vignai, followed by strong population isolation. On the other hand, P. rupicola underwent a remarkable genetic bottleneck during the Pleistocene glaciations, that shaped its present population structure. It seems likely that such shallow population structure is both the result of the minor degree of specialization to hypogean life and the higher dispersal ability characterizing this species. The simultaneous study of overlapping spider species showing different levels of adaptation to hypogean life, disclosed a new way to clarify patterns of biological diversification and to understand the effects of past climatic shift on the subterranean biodiversity. PMID:26734503

  13. Individual and species-specific traits explain niche size and functional role in spiders as generalist predators.

    PubMed

    Sanders, Dirk; Vogel, Esther; Knop, Eva

    2015-01-01

    The function of a predator within a community is greatly based on its trophic niche, that is the number and the strength of feeding links. In generalist predators, which feed on a wide range of prey, the size and position of the trophic niche is likely determined by traits such as hunting mode, the stratum they occur in, their body size and age. We used stable isotope analyses ((13)C and (15)N) to measure the trophic niche size of nine spider species within a forest hedge community and tested for species traits and individual traits that influence stable isotope enrichment, niche size and resource use. The spiders Enoplognatha, Philodromus, Floronia, and Heliophanus had large isotopic niches, which correspond to a more generalistic feeding behaviour. In contrast, Araneus, Metellina and Agelena, as top predators in the system, had rather narrow niches. We found a negative correlation between trophic position and niche size. Differences in trophic position in spiders were explained by body size, hunting modes and stratum, while niche size was influenced by hunting mode. In Philodromus, the size of the trophic niche increased significantly with age. Fitting spiders to functional groups according to their mean body size, hunting mode and their habitat domain resulted in largely separated niches, which indicates that these traits are meaningful for separating functional entities in spiders. Functional groups based on habitat domain (stratum) caught the essential functional differences between the species with species higher up in the vegetation feeding on flying insects and herb and ground species also preying on forest floor decomposers. Interestingly, we found a gradient from large species using a higher habitat domain and having a smaller niche to smaller species foraging closer to the ground and having a larger niche. This shows that even within generalist predators, such as spiders, there is a gradient of specialism that can be predicted by functional traits.

  14. A new spider species, Heser stoevi sp. nov., from Turkmenistan (Araneae: Gnaphosidae)

    PubMed Central

    2016-01-01

    Abstract Background The genus Heser (Araneae, Gnaphosidae) belongs to the Zelotes group, and is currently known to comprise 10 species distributed in Africa, Asia, Europe and North America. The type species is Heser malefactor Tuneva, 2004 from Kazakhstan. New information A new spider species, Heser stoevi sp. nov. (male and female) found in Koytendag Mountains, southeastern Turkmenistan is described and illustrated. It is morphologically close to H. aradensis (Levy, 1998) from Israel but can be readily distinguished by the longer embolus, the smaller and flattened conductor, the lack of retrolateral tibial apophysis, all this coupled with very distinctive female copulatory organs. The new species was found under stones in arid grassland habitats. PMID:27660520

  15. Securing Paternity by Mutilating Female Genitalia in Spiders.

    PubMed

    Mouginot, Pierick; Prügel, Josepha; Thom, Ulrike; Steinhoff, Philip O M; Kupryjanowicz, Janusz; Uhl, Gabriele

    2015-11-16

    Competition between males and their sperm over access to females and their eggs has resulted in manifold ways by which males try to secure paternity, ranging from physically guarding the female after mating to reducing her receptivity or her attractiveness to subsequent males by transferring manipulative substances or by mechanically sealing the female reproductive tract with a copulatory plug. Copulations may also result in internal damage of the female genitalia; however, this is not considered as a direct adaptation against sperm competition but as a collateral effect. Here, we present a drastic and direct mechanism for securing paternity: the removal of coupling structures on female genitalia by males. In the orb-weaving spider Larinia jeskovi males remove the scapus, a crucial coupling device on the female external genital region. Reconstruction of the coupling mechanism using micro-CT-scanned mating pairs revealed that several sclerites of the male genitalia interact to break off the scapus. Once it is removed, remating cannot occur due to mechanical coupling difficulties. In the field, male-inflicted genital damage is very prevalent since all female L. jeskovi were found to be mutilated at the end of the mating season. External genital mutilation is an overlooked but widely spread phenomenon since 80 additional spider species were found for which male genital manipulation can be suspected. Interlocking genitalia provide an evolutionary platform for the rapid evolution of this highly effective mechanism to secure paternity, and we suspect that other animal groups with interlocking genital structures might reveal similarly drastic male adaptations.

  16. An insecticidal peptide from the theraposid Brachypelma smithi spider venom reveals common molecular features among spider species from different genera.

    PubMed

    Corzo, Gerardo; Diego-García, Elia; Clement, Herlinda; Peigneur, Steve; Odell, George; Tytgat, Jan; Possani, Lourival D; Alagón, Alejandro

    2008-11-01

    The soluble venom of the Mexican theraposid spider Brachypelma smithi was screened for insecticidal peptides based on toxicity to house crickets. An insecticidal peptide, named Bs1 (which stands for Brachypelma smithi toxin 1) was obtained in homogeneous form after the soluble venom was fractionated using reverse-phase and cation-exchange chromatography. It contains 41 amino acids cross-linked by three disulfide bridges. Its sequence is similar to an insecticidal peptide isolated from the theraposid spider Ornithoctonus huwena from China, and another from the hexathelid spider Macrothelegigas from Japan, indicating that they are phylogenetically related. A cDNA library was prepared from the venomous glands of B. smithi and the gene that code for Bs1 was cloned. Sequence analysis of the nucleotides of Bs1 showed similarities to that of the hexathelid spider from Japan proving additional evidence for close genetic relationship between these spider peptides. The mRNAs of these toxins code for signal peptides that are processed at the segment rich in acidic and basic residues. Their C-terminal amino acids are amidated. However, they contain only a glycine residue at the most C-terminal position, without the presence of additional basic amino acid residues, normally required for post-translation processing of other toxins reported in the literature. The possible mechanism of action of Bs1 was investigated using several ion channels as putative receptors. Bs1 had minor, but significant effects on the Para/tipE insect ion channel, which could indirectly correlate with the observed lethal activity to crickets.

  17. An insecticidal peptide from the theraposid Brachypelma smithi spider venom reveals common molecular features among spider species from different genera.

    PubMed

    Corzo, Gerardo; Diego-García, Elia; Clement, Herlinda; Peigneur, Steve; Odell, George; Tytgat, Jan; Possani, Lourival D; Alagón, Alejandro

    2008-11-01

    The soluble venom of the Mexican theraposid spider Brachypelma smithi was screened for insecticidal peptides based on toxicity to house crickets. An insecticidal peptide, named Bs1 (which stands for Brachypelma smithi toxin 1) was obtained in homogeneous form after the soluble venom was fractionated using reverse-phase and cation-exchange chromatography. It contains 41 amino acids cross-linked by three disulfide bridges. Its sequence is similar to an insecticidal peptide isolated from the theraposid spider Ornithoctonus huwena from China, and another from the hexathelid spider Macrothelegigas from Japan, indicating that they are phylogenetically related. A cDNA library was prepared from the venomous glands of B. smithi and the gene that code for Bs1 was cloned. Sequence analysis of the nucleotides of Bs1 showed similarities to that of the hexathelid spider from Japan proving additional evidence for close genetic relationship between these spider peptides. The mRNAs of these toxins code for signal peptides that are processed at the segment rich in acidic and basic residues. Their C-terminal amino acids are amidated. However, they contain only a glycine residue at the most C-terminal position, without the presence of additional basic amino acid residues, normally required for post-translation processing of other toxins reported in the literature. The possible mechanism of action of Bs1 was investigated using several ion channels as putative receptors. Bs1 had minor, but significant effects on the Para/tipE insect ion channel, which could indirectly correlate with the observed lethal activity to crickets. PMID:18687374

  18. Four new Mouse Spider species (Araneae, Mygalomorphae, Actinopodidae, Missulena) from Western Australia

    PubMed Central

    Miglio, Laura Tavares; Harms, Danilo; Framenau, Volker Wilhelm; Harvey, Mark Stephen

    2014-01-01

    Abstract Four new species of the Mouse Spider genus Missulena Walckenaer, 1805 (family Actinopodidae) are described from Western Australia based on morphological features of adult males. Missulena leniae sp. n.(from the Carnarvon and Yalgoo biogeographic regions), Missulena mainae sp. n. (Carnarvon), Missulena melissae sp. n. (Pilbara) and Missulena pinguipes sp. n. (Mallee) represent a broad spectrum of morphological diversity found in this genus and differ from other congeners by details of the male copulatory bulb, colour patterns, eye sizes, leg morphology and leg spination. Two of the species, M. pinguipes sp. n. and M. mainae sp. n., are characterised by swollen metatarsi of the fourth legs in males, a feature not previously recorded in the family. A key to males of all named Missulena species from Australia is presented and allows their identification based on external morphology. PMID:24899853

  19. Variation in nesting behavior of eight species of spider mites, Stigmaeopsis having sociality

    NASA Astrophysics Data System (ADS)

    Saito, Yutaka; Zhang, Yan-Xuan; Mori, Kotaro; Ito, Katsura; Sato, Yukie; Chittenden, Anthony R.; Lin, Jian-Zhen; Chae, Younghae; Sakagami, Takane; Sahara, Ken

    2016-10-01

    Nesting behavior is considered to be an important element of social living in animals. The spider mites belonging to the genus Stigmaeopsis spend their lives within nests produced from silk threads. Several of these species show cooperative sociality, while the others are subsocial. In order to identify the origins of this social behavior, comparisons of nest sizes, nesting behaviors (making nests continuously or separately), and their associated traits (fecal deposition patterns) were made for eight cogeneric Stigmaeopsis species showing various levels of social development. All of these species inhabit bamboo plants (Poaceae). We initially addressed the proximate factor of nest size variation. The variation in nest size of the eight species corresponded well with the variation in dorsal seta sc1 length, suggesting that nest size variation among species may have a genetic basis. The time spent within a nest (nest duration) increased with nest size on the respective host plants. Nest arrangement patterns varied among species showing different sized nests: Large nest builders continuously extended their nests, while middle and small nest-building species built new separate nests, which resulted in different social interaction times among species, and is thought to be closely related to social development. Fecal deposition behaviors also varied among Stigmaeopsis species, suggesting diversity in anti-predatory adaptations. Finally, we discuss how the variation in sociality observed within this genus is likely the result of nest size variation that initially evolved as anti-predator strategies.

  20. High-stakes species delimitation in eyeless cave spiders (Cicurina, Dictynidae, Araneae) from central Texas.

    PubMed

    Hedin, Marshal

    2015-01-01

    A remarkable radiation of completely eyeless, cave-obligate spider species (Cicurina) has been described from limestone caves of Texas. This radiation includes over 50 described species, with a large number of hypothesized single-cave endemics, and four species listed as US Federally Endangered. Because of this conservation importance, species delimitation in the group is 'high-stakes'- it is imperative that species hypotheses are data rich, objective, and robust. This study focuses on a complex of four cave-dwelling Cicurina distributed on the northwestern edge of Austin, Texas. Several of the existing species hypotheses in this complex are weak, based on morphological comparisons of small samples of adult female specimens; one species description (for C. wartoni) is based on a single adult specimen. Species limits in this group were newly assessed using morphological, mitochondrial and nuclear DNA sequence data evidence, analysed using a variety of approaches. All data support a clear lineage separation between C. buwata versus the C. travisae complex (including C. travisae, C. wartoni and C. reddelli). Observed congruence across multiple analyses indicate that the C. travisae complex represents a single species, and the formal species synonymy presented here has important conservation implications. The integrative framework utilized in this study serves as a potential model for other Texas cave Cicurina, including US Federally Endangered species. More generally, this study illustrates how and why taxon-focused conservation efforts must prioritize modern species delimitation research (if the existing taxonomy is weak), before devoting precious downstream resources to conservation efforts. The study also highlights the issue of taxonomic type II error that diversity biologists increasingly face as species delimitation moves into the genomics era. PMID:25492722

  1. High-stakes species delimitation in eyeless cave spiders (Cicurina, Dictynidae, Araneae) from central Texas.

    PubMed

    Hedin, Marshal

    2015-01-01

    A remarkable radiation of completely eyeless, cave-obligate spider species (Cicurina) has been described from limestone caves of Texas. This radiation includes over 50 described species, with a large number of hypothesized single-cave endemics, and four species listed as US Federally Endangered. Because of this conservation importance, species delimitation in the group is 'high-stakes'- it is imperative that species hypotheses are data rich, objective, and robust. This study focuses on a complex of four cave-dwelling Cicurina distributed on the northwestern edge of Austin, Texas. Several of the existing species hypotheses in this complex are weak, based on morphological comparisons of small samples of adult female specimens; one species description (for C. wartoni) is based on a single adult specimen. Species limits in this group were newly assessed using morphological, mitochondrial and nuclear DNA sequence data evidence, analysed using a variety of approaches. All data support a clear lineage separation between C. buwata versus the C. travisae complex (including C. travisae, C. wartoni and C. reddelli). Observed congruence across multiple analyses indicate that the C. travisae complex represents a single species, and the formal species synonymy presented here has important conservation implications. The integrative framework utilized in this study serves as a potential model for other Texas cave Cicurina, including US Federally Endangered species. More generally, this study illustrates how and why taxon-focused conservation efforts must prioritize modern species delimitation research (if the existing taxonomy is weak), before devoting precious downstream resources to conservation efforts. The study also highlights the issue of taxonomic type II error that diversity biologists increasingly face as species delimitation moves into the genomics era.

  2. Bioaccumulation of Cry1Ab Protein from an Herbivore Reduces Anti-Oxidant Enzyme Activities in Two Spider Species

    PubMed Central

    Wang, Zhi; Tian, Yun; Tian, Yixing; Song, Qisheng

    2014-01-01

    Cry proteins are expressed in rice lines for lepidopteran pest control. These proteins can be transferred from transgenic rice plants to non-target arthropods, including planthoppers and then to a predatory spider. Movement of Cry proteins through food webs may reduce fitness of non-target arthropods, although recent publications indicated no serious changes in non-target populations. Nonetheless, Cry protein intoxication influences gene expression in Cry-sensitive insects. We posed the hypothesis that Cry protein intoxication influences enzyme activities in spiders acting in tri-trophic food webs. Here we report on the outcomes of experiments designed to test our hypothesis with two spider species. We demonstrated that the movement of CryAb protein from Drosophila culture medium into fruit flies maintained on the CryAb containing medium and from the flies to the spiders Ummeliata insecticeps and Pardosa pseudoannulata. We also show that the activities of three key metabolic enzymes, acetylcholine esterase (AchE), glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) were significantly influenced in the spiders after feeding on Cry1Ab-containing fruit flies. We infer from these data that Cry proteins originating in transgenic crops impacts non-target arthropods at the physiological and biochemical levels, which may be one mechanism of Cry protein-related reductions in fitness of non-target beneficial predators. PMID:24454741

  3. Cellular stress reactions assessed by gender and species in spiders from areas variously polluted with heavy metals.

    PubMed

    Wilczek, Grazyna; Babczyńska, Agnieszka; Wilczek, Piotr; Dolezych, Bogdan; Migula, Paweł; Młyńska, Hanna

    2008-05-01

    In the funnel web spider Agelena labyrinthica (Agelenidae; A. l.), sheet web spider Linyphia triangularis (Linyphiidae; L. t.) and wolf spider Xerolycosa nemoralis (Lycosidae; X. n.) from two differently polluted meadow sites in southern Poland, we studied the relations between antioxidant parameters (glutathione, GSH; glutathione peroxidases, GPOX, GSTPx; catalase, CAT; stress proteins-Hsp70, metallothioneins Mts), the intensity of apoptosis and necrosis, and heavy metal burdens of the midgut gland. Cellular reactions against stress caused by pollutants seemed to be sex-dependent. The concentrations of Zn and Cu in the midgut glands of male A. l. and X. n. were more than double that of the females, from both study sites. In male spiders from the heavily polluted site, both negative correlations (activity of caspase-3-like proteins vs Cu, Zn concentration; number of depolarized mitochondria vs Cu concentration) and positive correlations (number of necrotic cells vs Cu concentrations; activity of CAT vs Zn ) were noted. The defense of males against high metal content and its prooxidative effects is based mainly on GSH and CAT. In females the antioxidative reactions are species-specific and depend mainly on high peroxidase activity and on stress protein level. The increase in the number of apoptotic cells in the midgut gland of female spiders from the heavily polluted site suggests the defensive role of this process in maintaining the proper functioning of this organ.

  4. A Unique Nest-Protection Strategy in a New Species of Spider Wasp

    PubMed Central

    Zhu, Chao-Dong; Klein, Alexandra-Maria

    2014-01-01

    Hymenoptera show a great variation in reproductive potential and nesting behavior, from thousands of eggs in sawflies to just a dozen in nest-provisioning wasps. Reduction in reproductive potential in evolutionary derived Hymenoptera is often facilitated by advanced behavioral mechanisms and nesting strategies. Here we describe a surprising nesting behavior that was previously unknown in the entire animal kingdom: the use of a vestibular cell filled with dead ants in a new spider wasp (Hymenoptera: Pompilidae) species collected with trap nests in South-East China. We scientifically describe the ‘Bone-house Wasp’ as Deuteragenia ossarium sp. nov., named after graveyard bone-houses or ossuaries. We show that D. ossarium nests are less vulnerable to natural enemies than nests of other sympatric trap-nesting wasps, suggesting an effective nest protection strategy, most likely by utilizing chemical cues emanating from the dead ants. PMID:24987876

  5. Assessing spider species richness and composition in Mediterranean cork oak forests

    NASA Astrophysics Data System (ADS)

    Cardoso, Pedro; Gaspar, Clara; Pereira, Luis C.; Silva, Israel; Henriques, Sérgio S.; da Silva, Ricardo R.; Sousa, Pedro

    2008-01-01

    Semi-quantitative sampling protocols have been proposed as the most cost-effective and comprehensive way of sampling spiders in many regions of the world. In the present study, a balanced sampling design with the same number of samples per day, time of day, collector and method, was used to assess the species richness and composition of a Quercus suber woodland in Central Portugal. A total of 475 samples, each corresponding to one hour of effective fieldwork, were taken. One hundred sixty eight species were captured, of which 150 were recorded inside a delimited one-hectare plot; this number corresponds to around 90% of the estimated species richness. We tested the effect of applying different sampling approaches (sampling day, time of day, collector experience and method) on species richness, abundance, and composition. Most sampling approaches were found to influence the species measures, of which method, time of day and the respective interaction had the strongest influence. The data indicated that fauna depletion of the sampled area possibly occurred and that the inventory was reaching a plateau by the end of the sampling process. We advocate the use of the Chao estimators as best for intensive protocols limited in space and time and the use of the asymptotic properties of the Michaelis-Menten curve as a stopping or reliability rule, as it allows the investigator to know when a close-to-complete inventory has been obtained and when reliable non-parametric estimators have been achieved.

  6. Have male and female genitalia coevolved? A phylogenetic analysis of genitalic morphology and sexual size dimorphism in web-building spiders (Araneae: Araneoidea).

    PubMed

    Ramos, Margarita; Coddington, Jonathan A; Christenson, Terry E; Irschick, Duncan J

    2005-09-01

    Sexual size dimorphism (SSD) can strongly influence the evolution of reproductive strategies and life history. If SSD is extreme, and other characters (e.g., genitalic size) also increase with size, then functional conflicts may arise between the sexes. Spiders offer an excellent opportunity to investigate this issue because of their wide range of SSD. By using modern phylogenetic methods with 16 species of orb-weaving spiders, we provide strong evidence for the "positive genitalic divergence" model, implying that sexual genitalic dimorphism (SGD) increases as SSD increases. This pattern is supported by an evolutionary mismatch between the absolute sizes of male and female genitalia across species. Indeed, our findings reveal a dramatic reversal from male genitalia that are up to 87x larger than female genitalia in size-monomorphic species to female genitalia that are up to 2.8x larger in extremely size-dimorphic species. We infer that divergence in SGD could limit SSD both in spiders, and potentially in other taxa as well. Further, male and female body size, as well as male and female genitalia size, are decoupled evolutionarily. Finally, we show a negative scaling (hypoallometry) of male and female genitalic morphology within sexes. Evolutionary forces specific to each sex, such as larger female size (increased fecundity) or smaller male size (enhanced mate-searching ability), may be balanced by stabilizing selection on relative genitalic size.

  7. Similar patterns of frequency-dependent selection on animal personalities emerge in three species of social spiders.

    PubMed

    Lichtenstein, J L L; Pruitt, J N

    2015-06-01

    Frequency-dependent selection is thought to be a major contributor to the maintenance of phenotypic variation. We tested for frequency-dependent selection on contrasting behavioural strategies, termed here 'personalities', in three species of social spiders, each thought to represent an independent evolutionary origin of sociality. The evolution of sociality in the spider genus Anelosimus is consistently met with the emergence of two temporally stable discrete personality types: an 'aggressive' or 'docile' form. We assessed how the foraging success of each phenotype changes as a function of its representation within a colony. We did this by creating experimental colonies of various compositions (six aggressives, three aggressives and three dociles, one aggressive and five dociles, six dociles), maintaining them in a common garden for 3 weeks, and tracking the mass gained by individuals of either phenotype. We found that both the docile and aggressive phenotypes experienced their greatest mass gain in mixed colonies of mostly docile individuals. However, the performance of both phenotypes decreased as the frequency of the aggressive phenotype increased. Nearly identical patterns of phenotype-specific frequency dependence were recovered in all three species. Naturally occurring colonies of these spiders exhibit mixtures dominated by the docile phenotype, suggesting that these spiders may have evolved mechanisms to maintain the compositions that maximize the success of the colony without compromising the expected reproductive output of either phenotype.

  8. Gravito-inertial sensitivity of the spider - Araneus sericatus

    NASA Technical Reports Server (NTRS)

    Finck, A.

    1982-01-01

    The gravito-inertial transfer function of the orb-weaving spider was evaluated by changes in the cardiac reflex. A non-intrusive method, using a laser system recorded the cardiac pulse. Between 1.001 and 1.5 Gz the data are 'best-fit' by a log function (r-squared 0.92). The response of the neurogenic heart is seen to be a good dependent variable for invetebrate research. The arachnid lyriform organ has those qualities which complement the obtained gravity function. It is hypothesized that the cardiac pump maintains the spiders equilibrium in the gravito-inertial field.

  9. Down-regulation of plant defence in a resident spider mite species and its effect upon con- and heterospecifics.

    PubMed

    Godinho, Diogo P; Janssen, Arne; Dias, Teresa; Cruz, Cristina; Magalhães, Sara

    2016-01-01

    Herbivorous spider mites occurring on tomato plants (Solanum lycopersicum L.) cope with plant defences in various manners: the invasive Tetranychus evansi reduces defences below constitutive levels, whereas several strains of T. urticae induce such defences and others suppress them. In the Mediterranean region, these two species co-occur on tomato plants with T. ludeni, another closely related spider mite species. Unravelling how this third mite species affects plant defences is thus fundamental to understanding the outcome of herbivore interactions in this system. To test the effect of T. ludeni on tomato plant defences, we measured (1) the activity of proteinase inhibitors, indicating the induction of plant defences, in those plants, and (2) mite performance on plants previously infested with each mite species. We show that the performance of T. evansi and T. ludeni on plants previously infested with T. ludeni or T. evansi was better than on clean plants, indicating that these two mite species down-regulate plant defences. We also show that plants attacked by these mite species had lower activity of proteinase inhibitors than clean plants, whereas herbivory by T. urticae increased the activity of these proteins and resulted in reduced spider mite performance. This study thus shows that the property of down-regulation of plant defences below constitutive levels also occurs in T. ludeni.

  10. Two new species of whip spider (Amblypygi): an epigean and a cave dwelling Charinus Simon, 1892 from Belize.

    PubMed

    Miranda, Gustavo Silva De; Giupponi, Alessandro Ponce De Leão; Wizen, Gil

    2016-01-01

    Central America is rich in whip spider species, mainly of the genera Phrynus and Paraphrynus (Phrynidae), but also includes few registers of Charinus (Charinidae) with no description of taxa. In this paper two new species of Charinus from Belize are described and illustrated (Charinus belizensis sp. nov. and Charinus reddelli sp. nov.) being the first species named from Central America. New records of Charinus victori Armas, 2010 from Puerto Rico, a comparative table listing the differential characters of the Caribbean and Central American species, and a distributional map of those species are also provided. PMID:27394600

  11. Spiders (Araneae) of Churchill, Manitoba: DNA barcodes and morphology reveal high species diversity and new Canadian records

    PubMed Central

    2013-01-01

    Background Arctic ecosystems, especially those near transition zones, are expected to be strongly impacted by climate change. Because it is positioned on the ecotone between tundra and boreal forest, the Churchill area is a strategic locality for the analysis of shifts in faunal composition. This fact has motivated the effort to develop a comprehensive biodiversity inventory for the Churchill region by coupling DNA barcoding with morphological studies. The present study represents one element of this effort; it focuses on analysis of the spider fauna at Churchill. Results 198 species were detected among 2704 spiders analyzed, tripling the count for the Churchill region. Estimates of overall diversity suggest that another 10–20 species await detection. Most species displayed little intraspecific sequence variation (maximum <1%) in the barcode region of the cytochrome c oxidase subunit I (COI) gene, but four species showed considerably higher values (maximum = 4.1-6.2%), suggesting cryptic species. All recognized species possessed a distinct haplotype array at COI with nearest-neighbour interspecific distances averaging 8.57%. Three species new to Canada were detected: Robertus lyrifer (Theridiidae), Baryphyma trifrons (Linyphiidae), and Satilatlas monticola (Linyphiidae). The first two species may represent human-mediated introductions linked to the port in Churchill, but the other species represents a range extension from the USA. The first description of the female of S. monticola was also presented. As well, one probable new species of Alopecosa (Lycosidae) was recognized. Conclusions This study provides the first comprehensive DNA barcode reference library for the spider fauna of any region. Few cryptic species of spiders were detected, a result contrasting with the prevalence of undescribed species in several other terrestrial arthropod groups at Churchill. Because most (97.5%) sequence clusters at COI corresponded with a named taxon, DNA barcoding

  12. Dispatch from the field: ecology of ground-web-building spiders with description of a new species (Araneae, Symphytognathidae)

    PubMed Central

    2014-01-01

    Abstract Crassignatha danaugirangensis sp. n. (Araneae: Symphytognathidae) was discovered during a tropical ecology field course held at the Danau Girang Field Centre in Sabah, Malaysia. A taxonomic description and accompanying ecological study were completed as course activities. To assess the ecology of this species, which belongs to the ground-web-building spider community, three habitat types were surveyed: riparian forest, recently inundated riverine forest, and oil palm plantation. Crassignatha danaugirangensis sp. n. is the most abundant ground-web-building spider species in riparian forest; it is rare or absent from the recently inundated forest and was not found in a nearby oil palm plantation. The availability of this taxonomic description may help facilitate the accumulation of data about this species and the role of inundated riverine forest in shaping invertebrate communities. PMID:24891829

  13. A new species of wolf-spider (Alopecosa ogorodica sp.n.) from the Russian Mountain Altai with remarks on Arctosa meitanensis Yin et al., 1993 (Araneae: Lycosidae).

    PubMed

    Trilikauskas, Laimonas A; Azarkina, Galina N

    2014-08-25

    Alopecosa ogorodica sp.n. (♂♀), a new wolf-spider species (Lycosidae) from the Russian Mountain Altai is described. New data, diagnosis, description and drawings on Arctosa meitanensis Yin et al., 1993 are provided. 

  14. Description of a new species of Uroballus Simon, 1902 (Araneae: Salticidae) from Malaysia, with the longest spinnerets of any known jumping spider.

    PubMed

    Logunov, Dmitri V

    2014-01-01

    A new species Uroballus koponeni sp. n. (♀) from Malaysia (Borneo) is diagnosed, illustrated and described. The genus is unusual for jumping spiders in having extremely long spinnerets. PMID:25544631

  15. Web-building time in a spider: preliminary applications of ultrasonic detection.

    PubMed

    Ramousse, R; Davis, F

    1976-12-01

    Data collection on time and length of building in orb-weaving spiders has suffered from absence of light during construction and inconvenient hours. A simple apparatus is described which permits recording of the spiders' movements as they disturb an ultrasonic field. By varying onset and length of dark periods for two animals at even temperature and by registering the building periods for 127 webs, a definite influence of the light-dark cycle can be identified: there is a strong preference for building webs in the dark; this is superimposed on the circadian rhythm of orb-web construction. One of the spiders always built earlier than the other.

  16. Web-building time in a spider: preliminary applications of ultrasonic detection.

    PubMed

    Ramousse, R; Davis, F

    1976-12-01

    Data collection on time and length of building in orb-weaving spiders has suffered from absence of light during construction and inconvenient hours. A simple apparatus is described which permits recording of the spiders' movements as they disturb an ultrasonic field. By varying onset and length of dark periods for two animals at even temperature and by registering the building periods for 127 webs, a definite influence of the light-dark cycle can be identified: there is a strong preference for building webs in the dark; this is superimposed on the circadian rhythm of orb-web construction. One of the spiders always built earlier than the other. PMID:14677594

  17. Intragenic homogenization and multiple copies of prey-wrapping silk genes in Argiope garden spiders

    PubMed Central

    2014-01-01

    Background Spider silks are spectacular examples of phenotypic diversity arising from adaptive molecular evolution. An individual spider can produce an array of specialized silks, with the majority of constituent silk proteins encoded by members of the spidroin gene family. Spidroins are dominated by tandem repeats flanked by short, non-repetitive N- and C-terminal coding regions. The remarkable mechanical properties of spider silks have been largely attributed to the repeat sequences. However, the molecular evolutionary processes acting on spidroin terminal and repetitive regions remain unclear due to a paucity of complete gene sequences and sampling of genetic variation among individuals. To better understand spider silk evolution, we characterize a complete aciniform spidroin gene from an Argiope orb-weaving spider and survey aciniform gene fragments from congeneric individuals. Results We present the complete aciniform spidroin (AcSp1) gene from the silver garden spider Argiope argentata (Aar_AcSp1), and document multiple AcSp1 loci in individual genomes of A. argentata and the congeneric A. trifasciata and A. aurantia. We find that Aar_AcSp1 repeats have >98% pairwise nucleotide identity. By comparing AcSp1 repeat amino acid sequences between Argiope species and with other genera, we identify regions of conservation over vast amounts of evolutionary time. Through a PCR survey of individual A. argentata, A. trifasciata, and A. aurantia genomes, we ascertain that AcSp1 repeats show limited variation between species whereas terminal regions are more divergent. We also find that average dN/dS across codons in the N-terminal, repetitive, and C-terminal encoding regions indicate purifying selection that is strongest in the N-terminal region. Conclusions Using the complete A. argentata AcSp1 gene and spidroin genetic variation between individuals, this study clarifies some of the molecular evolutionary processes underlying the spectacular mechanical attributes of

  18. A checklist of Indian armored spiders (Araneae, Tetrablemmidae) with the description of a new species from the Western Ghats.

    PubMed

    Sankaran, Pradeep M; Sebastian, Pothalil A

    2016-01-01

    The Oriental armored spider genus Shearella Lehtinen, 1981 is recorded for the first time from India. Detailed description and illustrations of both sexes of Shearella alii sp. nov. are given. The geographic distribution of the genus is updated. Sinamma sanya (Lin & Li, 2010) is transferred back to Shearella, and Shearella browni (Shear, 1978) back to Monoblemma Gertsch, 1941. A checklist of all Indian tetrablemmid species currently known and a distribution map of all known Shearella spp. are presented. PMID:27394275

  19. Sexual dimorphism in venom chemistry in Tetragnatha spiders is not easily explained by adult niche differences.

    PubMed

    Binford, Greta J; Gillespie, Rosemary G; Maddison, Wayne P

    2016-05-01

    Spider venom composition typically differs between sexes. This pattern is anecdotally thought to reflect differences in adult feeding biology. We used a phylogenetic approach to compare intersexual venom dimorphism between species that differ in adult niche dimorphism. Male and female venoms were compared within and between related species of Hawaiian Tetragnatha, a mainland congener, and outgroups. In some species of Hawaiian Tetragnatha adult females spin orb-webs and adult males capture prey while wandering, while in other species both males and females capture prey by wandering. We predicted that, if venom sexual dimorphism is primarily explained by differences in adult feeding biology, species in which both sexes forage by wandering would have monomorphic venoms or venoms with reduced dimorphism relative to species with different adult feeding biology. However, we found striking sexual dimorphism in venoms of both wandering and orb-weaving Tetragnatha species with males having high molecular weight components in their venoms that were absent in females, and a reduced concentration of low molecular weight components relative to females. Intersexual differences in venom composition within Tetragnatha were significantly larger than in non-Tetragnatha species. Diet composition was not different between sexes. This striking venom dimorphism is not easily explained by differences in feeding ecology or behavior. Rather, we hypothesize that the dimorphism reflects male-specific components that play a role in mating biology possibly in sexual stimulation, nuptial gifts and/or mate recognition.

  20. Species replacement by a nonnative salmonid alters ecosystem function by reducing prey subsidies that support riparian spiders.

    PubMed

    Benjamin, Joseph R; Fausch, Kurt D; Baxter, Colden V

    2011-10-01

    Replacement of a native species by a nonnative can have strong effects on ecosystem function, such as altering nutrient cycling or disturbance frequency. Replacements may cause shifts in ecosystem function because nonnatives establish at different biomass, or because they differ from native species in traits like foraging behavior. However, no studies have compared effects of wholesale replacement of a native by a nonnative species on subsidies that support consumers in adjacent habitats, nor quantified the magnitude of these effects. We examined whether streams invaded by nonnative brook trout (Salvelinus fontinalis) in two regions of the Rocky Mountains, USA, produced fewer emerging adult aquatic insects compared to paired streams with native cutthroat trout (Oncorhynchus clarkii), and whether riparian spiders that depend on these prey were less abundant along streams with lower total insect emergence. As predicted, emergence density was 36% lower from streams with the nonnative fish. Biomass of brook trout was higher than the cutthroat trout they replaced, but even after accounting for this difference, emergence was 24% lower from brook trout streams. More riparian spiders were counted along streams with greater total emergence across the water surface. Based on these results, we predicted that brook trout replacement would result in 6-20% fewer spiders in the two regions. When brook trout replace cutthroat trout, they reduce cross-habitat resource subsidies and alter ecosystem function in stream-riparian food webs, not only owing to increased biomass but also because traits apparently differ from native cutthroat trout. PMID:21688160

  1. Species replacement by a nonnative salmonid alters ecosystem function by reducing prey subsidies that support riparian spiders

    USGS Publications Warehouse

    Benjamin, J.R.; Fausch, K.D.; Baxter, C.V.

    2011-01-01

    Replacement of a native species by a nonnative can have strong effects on ecosystem function, such as altering nutrient cycling or disturbance frequency. Replacements may cause shifts in ecosystem function because nonnatives establish at different biomass, or because they differ from native species in traits like foraging behavior. However, no studies have compared effects of wholesale replacement of a native by a nonnative species on subsidies that support consumers in adjacent habitats, nor quantified the magnitude of these effects. We examined whether streams invaded by nonnative brook trout (Salvelinus fontinalis) in two regions of the Rocky Mountains, USA, produced fewer emerging adult aquatic insects compared to paired streams with native cutthroat trout (Oncorhynchus clarkii), and whether riparian spiders that depend on these prey were less abundant along streams with lower total insect emergence. As predicted, emergence density was 36% lower from streams with the nonnative fish. Biomass of brook trout was higher than the cutthroat trout they replaced, but even after accounting for this difference, emergence was 24% lower from brook trout streams. More riparian spiders were counted along streams with greater total emergence across the water surface. Based on these results, we predicted that brook trout replacement would result in 6-20% fewer spiders in the two regions. When brook trout replace cutthroat trout, they reduce cross-habitat resource subsidies and alter ecosystem function in stream-riparian food webs, not only owing to increased biomass but also because traits apparently differ from native cutthroat trout. ?? 2011 Springer-Verlag.

  2. Species replacement by a nonnative salmonid alters ecosystem function by reducing prey subsidies that support riparian spiders.

    PubMed

    Benjamin, Joseph R; Fausch, Kurt D; Baxter, Colden V

    2011-10-01

    Replacement of a native species by a nonnative can have strong effects on ecosystem function, such as altering nutrient cycling or disturbance frequency. Replacements may cause shifts in ecosystem function because nonnatives establish at different biomass, or because they differ from native species in traits like foraging behavior. However, no studies have compared effects of wholesale replacement of a native by a nonnative species on subsidies that support consumers in adjacent habitats, nor quantified the magnitude of these effects. We examined whether streams invaded by nonnative brook trout (Salvelinus fontinalis) in two regions of the Rocky Mountains, USA, produced fewer emerging adult aquatic insects compared to paired streams with native cutthroat trout (Oncorhynchus clarkii), and whether riparian spiders that depend on these prey were less abundant along streams with lower total insect emergence. As predicted, emergence density was 36% lower from streams with the nonnative fish. Biomass of brook trout was higher than the cutthroat trout they replaced, but even after accounting for this difference, emergence was 24% lower from brook trout streams. More riparian spiders were counted along streams with greater total emergence across the water surface. Based on these results, we predicted that brook trout replacement would result in 6-20% fewer spiders in the two regions. When brook trout replace cutthroat trout, they reduce cross-habitat resource subsidies and alter ecosystem function in stream-riparian food webs, not only owing to increased biomass but also because traits apparently differ from native cutthroat trout.

  3. A novel property of spider silk: chemical defence against ants.

    PubMed

    Zhang, Shichang; Koh, Teck Hui; Seah, Wee Khee; Lai, Yee Hing; Elgar, Mark A; Li, Daiqin

    2012-05-01

    Spider webs are made of silk, the properties of which ensure remarkable efficiency at capturing prey. However, remaining on, or near, the web exposes the resident spiders to many potential predators, such as ants. Surprisingly, ants are rarely reported foraging on the webs of orb-weaving spiders, despite the formidable capacity of ants to subdue prey and repel enemies, the diversity and abundance of orb-web spiders, and the nutritional value of the web and resident spider. We explain this paradox by reporting a novel property of the silk produced by the orb-web spider Nephila antipodiana (Walckenaer). These spiders deposit on the silk a pyrrolidine alkaloid (2-pyrrolidinone) that provides protection from ant invasion. Furthermore, the ontogenetic change in the production of 2-pyrrolidinone suggests that this compound represents an adaptive response to the threat of natural enemies, rather than a simple by-product of silk synthesis: while 2-pyrrolidinone occurs on the silk threads produced by adult and large juvenile spiders, it is absent on threads produced by small juvenile spiders, whose threads are sufficiently thin to be inaccessible to ants.

  4. Phylogeny suggests nondirectional and isometric evolution of sexual size dimorphism in argiopine spiders.

    PubMed

    Cheng, Ren-Chung; Kuntner, Matjaž

    2014-10-01

    Sexual dimorphism describes substantial differences between male and female phenotypes. In spiders, sexual dimorphism research almost exclusively focuses on size, and recent studies have recovered steady evolutionary size increases in females, and independent evolutionary size changes in males. Their discordance is due to negative allometric size patterns caused by different selection pressures on male and female sizes (converse Rensch's rule). Here, we investigated macroevolutionary patterns of sexual size dimorphism (SSD) in Argiopinae, a global lineage of orb-weaving spiders with varying degrees of SSD. We devised a Bayesian and maximum-likelihood molecular species-level phylogeny, and then used it to reconstruct sex-specific size evolution, to examine general hypotheses and different models of size evolution, to test for sexual size coevolution, and to examine allometric patterns of SSD. Our results, revealing ancestral moderate sizes and SSD, failed to reject the Brownian motion model, which suggests a nondirectional size evolution. Contrary to predictions, male and female sizes were phylogenetically correlated, and SSD evolution was isometric. We interpret these results to question the classical explanations of female-biased SSD via fecundity, gravity, and differential mortality. In argiopines, SSD evolution may be driven by these or additional selection mechanisms, but perhaps at different phylogenetic scales.

  5. A new species of spider belonging to the Pardosa lugubris-group (Araneae: Lycosidae) from Far East Asia.

    PubMed

    Nadolny, Anton A; Omelko, Mikhail M; Marusik, Yuri M; Blagoev, Gergin

    2016-01-01

    A new species, Pardosa koponeni sp. n., is described. The new species is widely distributed in Far East Asia. It was previously confused with P. lugubris (Walckenaer, 1802). The two species have very similar copulatory organs but differ in the colouration of legs II-IV in males and the carapace/femur I ratio in both sexes. The distribution of the new species is mapped using material examined and literature data. To provide a more complete understanding of the boundaries between such closely related species, morphological and DNA barcoding approaches for species discrimination were integrated. Two species of the Pardosa lugubris-group (P. lugubris and P. alacris) were found to share haplotypes, suggesting evidence of hybridization or incomplete lineage sorting, or they are perhaps separate morphotypes of the same species. This is another example of complexity and the value of comparing morphology and DNA barcode data among spiders. PMID:27395923

  6. Typhlonesticus gocmeni sp. n., a new cave-dwelling blind spider species from the Aegean region of Turkey (Araneae, Nesticidae)

    PubMed Central

    Ribera, Carles; Elverici, Mert; Kunt, Kadir Boğaç; Özkütük, Recep Sulhi

    2014-01-01

    Abstract A new species of the troglobitic spider genus Typhlonesticus is described from specimens found in Keloğlan Cave (Denizli Province, Dodurgalar Town), Turkey. Typhlonesticus gocmeni sp. n. is described on the basis of both sexes; and its phylogenetic relationships with closely related European genera and species are discussed based on morphological and molecular data (the cox1, rrnL and H3 genes). Three new combinations are proposed: Typhlonesticus idriacus (Roewer, 1931), comb. n., Typhlonesticus morisii (Brignoli, 1975) comb. n. and Typhlonesticus obcaecatus (Simon, 1907), comb. n. all ex Nesticus. PMID:25061362

  7. New species of the spider genera Aysenia and Aysenoides from Chile and Argentina: description and phylogenetic relationships (Araneae: Anyphaenidae, Amaurobioidinae).

    PubMed

    Laborda, Alvaro; Ramírez, Martín J; Pizarro-Araya, Jaime

    2013-01-01

    New spider species of the genera Aysenia Tullgren and Aysenoides Ramírez are described and their phylogenetic relationships discussed. The new species Aysenia paposo, from the coastal desert in northern Chile is sister to Aysenia araucana Ramírez. The diagnosis of Aysenia araucana is updated and new somatic variability is reported for the species. We present new records for other species of Aysenia and Aysenoides. The new species Aysenoides simoi, from temperate forests in Chile and adjacent Argentina is sister to Aysenoides nahuel. The phylogenetic analysis confirmed the monophyly of both genera. The support values of the genera are relatively high, but some internal branches show low support values. The genus Aysenia is supported by three synapomorphies, two of these from leg spination and one from the male genitalia. Aysenoides is supported by three synapomorphies from male and female genitalia. PMID:25277558

  8. A new species of jumping spider Neonella Gertsch, with notes on the genus and male identification key (Araneae, Salticidae).

    PubMed

    Rubio, Gonzalo D; Argañaraz, Carina I; Gleiser, Raquel M

    2015-01-01

    The American genus Neonella Gertsch, 1936 consists of very small jumping spiders whose biology is not well known. The genus currently includes eleven valid species, of which eight are known from both sexes and two are only known from one sex. This paper describes and illustrates a new species Neonella acostae sp. n., demonstrates male palpal variation in Neonella montana Galiano, 1988, and provides some information on the ecology of three sympatric species. New records of Neonella montana and Neonella minuta Galiano, 1965 are reported. Because the previously described species of Neonella were well illustrated and diagnosed, a dichotomous key to males is given along with genital illustrations of both sexes for all known species. PMID:26692804

  9. A new species of jumping spider Neonella Gertsch, with notes on the genus and male identification key (Araneae, Salticidae)

    PubMed Central

    Rubio, Gonzalo D.; Argañaraz, Carina I.; Gleiser, Raquel M.

    2015-01-01

    Abstract The American genus Neonella Gertsch, 1936 consists of very small jumping spiders whose biology is not well known. The genus currently includes eleven valid species, of which eight are known from both sexes and two are only known from one sex. This paper describes and illustrates a new species Neonella acostae sp. n., demonstrates male palpal variation in Neonella montana Galiano, 1988, and provides some information on the ecology of three sympatric species. New records of Neonella montana and Neonella minuta Galiano, 1965 are reported. Because the previously described species of Neonella were well illustrated and diagnosed, a dichotomous key to males is given along with genital illustrations of both sexes for all known species. PMID:26692804

  10. Respiration in spiders (Araneae).

    PubMed

    Schmitz, Anke

    2016-05-01

    Spiders (Araneae) are unique regarding their respiratory system: they are the only animal group that breathe simultaneously with lungs and tracheae. Looking at the physiology of respiration the existence of tracheae plays an important role in spiders with a well-developed tracheal system. Other factors as sex, life time, type of prey capture and the high ability to gain energy anaerobically influence the resting and the active metabolic rate intensely. Most spiders have metabolic rates that are much lower than expected from body mass; but especially those with two pairs of lungs. Males normally have higher resting rates than females; spiders that are less evolved and possess a cribellum have lower metabolic rates than higher evolved species. Freely hunting spiders show a higher energy turnover than spiders hunting with a web. Spiders that live longer than 1 year will have lower metabolic rates than those species that die after 1 year in which development and reproduction must be completed. Lower temperatures and starvation, which most spiders can cope with, will decrease the metabolic rate as well. PMID:26820263

  11. Signal complexity and modular organization of the courtship behaviours of two sibling species of wolf spiders (Araneae: Lycosidae).

    PubMed

    Chiarle, Alberto; Isaia, Marco

    2013-07-01

    In this study, we compare the courtship behaviours of Pardosa proxima and P. vlijmi, two species of wolf spiders up to now regarded as "ethospecies", by means of motion analysis methodologies. In particular, we investigate the features of the signals, aiming at understanding the evolution of the courtship and its role in species delimitation and speciation processes. In our model, we highlight a modular structure of the behaviours and the presence of recurring units and phases. According to other similar cases concerning animal communication, we observed one highly variable and one stereotyped phase for both species. The stereotyped phase is here regarded as a signal related to species identity or an honest signal linked directly to the quality of the signaler. On the contrary, the variable phase aims to facilitate signal detection and assessment by the female reducing choice costs or errors. Variable phases include cues arisen from Fisherian runaway selection, female sensory exploitation and remaining of past selections.

  12. Multilocus genealogies reveal multiple cryptic species and biogeographical complexity in the California turret spider Antrodiaetus riversi (Mygalomorphae, Antrodiaetidae).

    PubMed

    Starrett, James; Hedin, Marshal

    2007-02-01

    Antrodiaetus riversi (Araneae, Antrodiaetidae) is a dispersal-limited, habitat specialized mygalomorph spider species endemic to mesic woodlands of northern and central California. This species occupies a disjunct distribution, with populations in the Sierra Nevada and Coast Ranges, separated by the inhospitable Central Valley. Previous studies of morphological and allozyme variation have suggested that these populations may constitute cryptic species. We investigated the phylogeography of A. riversi using both nuclear and mitochondrial DNA sequences, collected for a comprehensive population sample. These data reveal the presence of at least five species in the A. riversi complex - these species are deeply diverged, and genealogically exclusive in both nuclear and mitochondrial genomes. Each of these species is characterized by extreme population subdivision and deep phylogeographical structuring, consistent with minimal gene flow across the dissected Californian landscape. Three species are restricted to the Coast Ranges, one to high altitudes of the central Sierran Nevada, and one species is found in both ranges. These species have allopatric distributions, although species parapatry is hypothesized to occur in several areas. Species diversification appears to have pulsed in the Late Miocene/Early Pliocene, a timing consistent with biogeographical reconstructions for many Californian taxa, and a time of turbulent geological activity in the region.

  13. Adjustment of web-building initiation to high humidity: a constraint by humidity-dependent thread stickiness in the spider Cyrtarachne

    NASA Astrophysics Data System (ADS)

    Baba, Yuki G.; Kusahara, Miki; Maezono, Yasunori; Miyashita, Tadashi

    2014-07-01

    Cyrtarachne is an orb-weaving spider belonging to the subfamily Cyrtarachninae (Araneidae) which includes triangular-web-building Pasilobus and bolas spiders. The Cyrtarachninae is a group of spiders specialized in catching moths, which is thought to have evolved from ordinary orb-weaving araneids. Although the web-building time of nocturnal spiders is in general related to the time of sunset, anecdotal evidence has suggested variability of web-building time in Cyrtarachne and its closely related genera. This study has examined the effects of temperature, humidity, moonlight intensity, and prey (moths) availability on web-building time of Cyrtarachne bufo, Cyrtarachne akirai, and Cyrtarachne nagasakiensis. Generalized linear mixed model (GLMM) have revealed that humidity, and not prey availability, was the essential variable that explained the daily variability of web-building time. Experiments measuring thread stickiness under different humidities showed that, although the thread of Cyrtarachne was found to have strong stickiness under high humidity, low humidity caused a marked decrease of thread stickiness. By contrast, no obvious change in stickiness was seen in an ordinary orb-weaving spider, Larinia argiopiformis. These findings suggest that Cyrtarachne adjusts its web-building time to favorable conditions of high humidity maintaining strong stickiness, which enables the threads to work efficiently for capturing prey.

  14. Adjustment of web-building initiation to high humidity: a constraint by humidity-dependent thread stickiness in the spider Cyrtarachne.

    PubMed

    Baba, Yuki G; Kusahara, Miki; Maezono, Yasunori; Miyashita, Tadashi

    2014-07-01

    Cyrtarachne is an orb-weaving spider belonging to the subfamily Cyrtarachninae (Araneidae) which includes triangular-web-building Pasilobus and bolas spiders. The Cyrtarachninae is a group of spiders specialized in catching moths, which is thought to have evolved from ordinary orb-weaving araneids. Although the web-building time of nocturnal spiders is in general related to the time of sunset, anecdotal evidence has suggested variability of web-building time in Cyrtarachne and its closely related genera. This study has examined the effects of temperature, humidity, moonlight intensity, and prey (moths) availability on web-building time of Cyrtarachne bufo, Cyrtarachne akirai, and Cyrtarachne nagasakiensis. Generalized linear mixed model (GLMM) have revealed that humidity, and not prey availability, was the essential variable that explained the daily variability of web-building time. Experiments measuring thread stickiness under different humidities showed that, although the thread of Cyrtarachne was found to have strong stickiness under high humidity, low humidity caused a marked decrease of thread stickiness. By contrast, no obvious change in stickiness was seen in an ordinary orb-weaving spider, Larinia argiopiformis. These findings suggest that Cyrtarachne adjusts its web-building time to favorable conditions of high humidity maintaining strong stickiness, which enables the threads to work efficiently for capturing prey.

  15. Speciation history of the North American funnel web spiders, Agelenopsis (Araneae: Agelenidae): phylogenetic inferences at the population-species interface.

    PubMed

    Ayoub, Nadia A; Riechert, Susan E; Small, Randall L

    2005-07-01

    Intra- and interspecific relationships of 12 out of 13 described species as well as a potential new species in the spider genus Agelenopsis (Araneae: Agelenidae) were analyzed using sequence data from two mitochondrial genes, cytochrome oxidase I (COI) and 16S ribosomal RNA. Approximately half of the species examined formed well-supported monophyletic groups, whereas the rest of the species were part of well-supported monophyletic species groups. Rather than viewing cases where species were not identified as being monophyletic as poor taxonomy, these cases more likely represent recent speciation and offer insights into the process of speciation. The clade with the lowest levels of interspecific sequence divergence was found in eastern North America, whereas western species displayed much higher levels of interspecific divergence. These patterns appear to extend below the species level as well, with southwestern species exhibiting the highest levels of intraspecific sequence divergence and geographic structuring. The relationship between Agelenopsis and Barronopsis, a genus once considered a sub-genus of Agelenopsis, was also examined. The two genera are reciprocally monophyletic but more generic level sampling is needed to confirm an apparent sister relationship between the two.

  16. More data, fewer shifts: molecular insights into the evolution of the spinning apparatus in non-orb-weaving spiders.

    PubMed

    Spagna, Joseph C; Gillespie, Rosemary G

    2008-01-01

    All spiders produce silk and use it for various functions throughout their lives, but not all spiders produce the same silks, or use them for the same functions. These functions may include building shelters, protecting eggs, and trapping prey. The "RTA clade" of spiders (grass spiders, jumping-spiders, wolf spiders, hackled-band weavers, etc.) is an extremely diverse group ( approximately 18,000 species, representing nearly half of all described species), with great variation in ecology and morphology, including variation in the cribellum, a specialized silk-producing organ. The loss of the cribellum, a structure that produces fibers contributing stickiness to prey snares and which is invariably associated with a set of accessory structures, has been studied in orb-web-weavers and shown to have been lost once during the evolutionary history of the group, but never regained. Relative to the orb-weavers, evolution of the structure remains less-thoroughly studied in the RTA clade. As the cribellum is one member of a suite of traits, the combined action of which is essential in prey-capture, its loss should have ecological correlates or physiological trade-offs of evolutionary interest. Using molecular data from nuclear genes (ribosomal DNAs 18S and 28S, and protein-coding Histone H3), as well as mitochondrial data (Cytochrome oxidase I) totaling approximately 3400 base pairs, we developed a phylogenetic hypothesis for three-clawed lineages in this group, focusing on families where taxonomy and previous cladistic analyses suggest multiple losses, or possibly loss and secondary gain, of the cribellum. Results of Bayesian and direct-optimization (POY) analyses agree on a well-resolved and robust agelenid clade that includes the putative subfamilies Ageleninae, Tegenariinae, Textricinae and Coelotinae, but excludes the cribellate New Zealand genus Neoramia. Optimizing the pattern of cribellum evolution onto these trees shows that the cribellate state is conserved in

  17. More data, fewer shifts: molecular insights into the evolution of the spinning apparatus in non-orb-weaving spiders.

    PubMed

    Spagna, Joseph C; Gillespie, Rosemary G

    2008-01-01

    All spiders produce silk and use it for various functions throughout their lives, but not all spiders produce the same silks, or use them for the same functions. These functions may include building shelters, protecting eggs, and trapping prey. The "RTA clade" of spiders (grass spiders, jumping-spiders, wolf spiders, hackled-band weavers, etc.) is an extremely diverse group ( approximately 18,000 species, representing nearly half of all described species), with great variation in ecology and morphology, including variation in the cribellum, a specialized silk-producing organ. The loss of the cribellum, a structure that produces fibers contributing stickiness to prey snares and which is invariably associated with a set of accessory structures, has been studied in orb-web-weavers and shown to have been lost once during the evolutionary history of the group, but never regained. Relative to the orb-weavers, evolution of the structure remains less-thoroughly studied in the RTA clade. As the cribellum is one member of a suite of traits, the combined action of which is essential in prey-capture, its loss should have ecological correlates or physiological trade-offs of evolutionary interest. Using molecular data from nuclear genes (ribosomal DNAs 18S and 28S, and protein-coding Histone H3), as well as mitochondrial data (Cytochrome oxidase I) totaling approximately 3400 base pairs, we developed a phylogenetic hypothesis for three-clawed lineages in this group, focusing on families where taxonomy and previous cladistic analyses suggest multiple losses, or possibly loss and secondary gain, of the cribellum. Results of Bayesian and direct-optimization (POY) analyses agree on a well-resolved and robust agelenid clade that includes the putative subfamilies Ageleninae, Tegenariinae, Textricinae and Coelotinae, but excludes the cribellate New Zealand genus Neoramia. Optimizing the pattern of cribellum evolution onto these trees shows that the cribellate state is conserved in

  18. Glyphosate-based herbicide has contrasting effects on prey capture by two co-occurring wolf spider species.

    PubMed

    Rittman, Sandra; Wrinn, Kerri M; Evans, Samuel C; Webb, Alex W; Rypstra, Ann L

    2013-10-01

    Anthropogenic substances have the potential to affect animal behavior either because they present a novel stimulus or because they interfere with natural chemical communication pathways. Such shifts can alter the dynamic between predators and potential prey, which might affect population success as well as the strength of food web linkages. We examined the foraging of two wolf spiders, Tigrosa helluo and Pardosa milvina (Araneae, Lycosidae), that are abundant in agroecosystems where they are routinely exposed to herbicides. We tested the hypothesis that the presence of a commercial formulation of a glyphosate-based herbicide would affect the prey capture behavior of these two wolf spiders. We tested the larger Tigrosa foraging on Pardosa or crickets (Acheta domesticus) and the smaller Pardosa foraging on crickets. Tigrosa subdued crickets more quickly and with fewer lunges than it took them to capture Pardosa. The presence of herbicide allowed Tigrosa to orient toward and capture both prey species more quickly but it did not affect the number of lunges required to subdue either prey. Herbicide did not affect the timing of prey capture for Pardosa but it did cause them to use more lunges in the process. Thus, herbicide had contrasting effects on foraging behavior of these two agrobiont predators, which means that it could shift the direction and strength of food web linkages in complex ways. PMID:24122113

  19. Molecular basis of the remarkable species selectivity of an insecticidal sodium channel toxin from the African spider Augacephalus ezendami

    PubMed Central

    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.

    2016-01-01

    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. PMID:27383378

  20. Glyphosate-based herbicide has contrasting effects on prey capture by two co-occurring wolf spider species.

    PubMed

    Rittman, Sandra; Wrinn, Kerri M; Evans, Samuel C; Webb, Alex W; Rypstra, Ann L

    2013-10-01

    Anthropogenic substances have the potential to affect animal behavior either because they present a novel stimulus or because they interfere with natural chemical communication pathways. Such shifts can alter the dynamic between predators and potential prey, which might affect population success as well as the strength of food web linkages. We examined the foraging of two wolf spiders, Tigrosa helluo and Pardosa milvina (Araneae, Lycosidae), that are abundant in agroecosystems where they are routinely exposed to herbicides. We tested the hypothesis that the presence of a commercial formulation of a glyphosate-based herbicide would affect the prey capture behavior of these two wolf spiders. We tested the larger Tigrosa foraging on Pardosa or crickets (Acheta domesticus) and the smaller Pardosa foraging on crickets. Tigrosa subdued crickets more quickly and with fewer lunges than it took them to capture Pardosa. The presence of herbicide allowed Tigrosa to orient toward and capture both prey species more quickly but it did not affect the number of lunges required to subdue either prey. Herbicide did not affect the timing of prey capture for Pardosa but it did cause them to use more lunges in the process. Thus, herbicide had contrasting effects on foraging behavior of these two agrobiont predators, which means that it could shift the direction and strength of food web linkages in complex ways.

  1. Molecular basis of the remarkable species selectivity of an insecticidal sodium channel toxin from the African spider Augacephalus ezendami.

    PubMed

    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

    2016-01-01

    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. PMID:27383378

  2. Description of a novel mating plug mechanism in spiders and the description of the new species Maeota setastrobilaris (Araneae, Salticidae)

    PubMed Central

    Garcilazo-Cruz, Uriel; Alvarez-Padilla, Fernando

    2015-01-01

    Abstract Reproduction in arthropods is an interesting area of research where intrasexual and intersexual mechanisms have evolved structures with several functions. The mating plugs usually produced by males are good examples of these structures where the main function is to obstruct the female genitalia against new sperm depositions. In spiders several types of mating plugs have been documented, the most common ones include solidified secretions, parts of the bulb or in some extraordinary cases the mutilation of the entire palpal bulb. Here, we describe the first case of modified setae, which are located on the cymbial dorsal base, used directly as a mating plug for the Order Araneae in the species Maeota setastrobilaris sp. n. In addition the taxonomic description of Maeota setastrobilaris sp. n. is provided and based on our findings the geographic distribution of this genus is extended to the Northern hemisphere. PMID:26175601

  3. Fossil spiders.

    PubMed

    Selden, Paul A; Penney, David

    2010-02-01

    Over the last three decades, the fossil record of spiders has increased from being previously biased towards Tertiary ambers and a few dubious earlier records, to one which reveals a much greater diversity in the Mesozoic, with many of the modern families present in that era, and with clearer evidence of the evolutionary history of the group. We here record the history of palaeoarachnology and the major breakthroughs which form the basis of studies on fossil spiders. Understanding the preservation and taphonomic history of spider fossils is crucial to interpretation of fossil spider morphology. We also review the more recent descriptions of fossil spiders and the effect these discoveries have had on the phylogenetic tree of spiders. We discuss some features of the evolutionary history of spiders and present ideas for future work.

  4. Species diversification patterns in the Polynesian jumping spider genus Havaika Prószyński, 2001 (Araneae, Salticidae).

    PubMed

    Arnedo, Miquel A; Gillespie, Rosemary G

    2006-11-01

    Hotspot archipelagoes provide exceptional models for the study of the evolutionary process, due to the effects of isolation and topographical diversity in inducing the formation of unique biotic assemblages. In this paper, we examine the evolutionary patterns exhibited by the jumping spider genus Havaika Prószyński, 2001 in the Polynesian islands of the Hawaiian and Marquesas chains. To date, systematic research on Havaika has been seriously limited by the poor taxonomic knowledge on the group, which was based on a handful of specimens that showed continuous variability and lacked clear-cut diagnostic characters. Here, we circumvent this problem by inferring a phylogeny based on DNA sequences of several fragments including both mitochondrial (protein coding cytochrome oxidase I, NAD1 dehydrogenase, ribosomal 16S, and tRNA leu) and nuclear (internal transcribed spacer 2) genes, and a statistical morphological analyses of a large sample of specimens. Results suggest that the Marquesan and Hawaiian Havaika may be the result of independent colonizations. Furthermore, data provide little support for the standard "progression rule" (evolution in the direction of older to younger islands) in Hawaiian Islands. This may be explained by a recent arrival of the group: age estimates of the different lineages suggest that Havaika colonized the Hawaiian Islands after most of the extant islands were already formed. The lack of clear-cut diagnostic characters among species may also be explained by the recent origin of the group since molecular data do not provide any evidence of hybridization among lineages. Quantitative morphological data coupled with the phylogenetic information allow us to reevaluate the current limitation of Havaika taxonomy. Molecular data support the existence of at least four different evolutionary lineages that are further morphologically diagnosable. However, genealogical relationships are better predicted by geographical affinity (i.e. island) than by

  5. Species diversification patterns in the Polynesian jumping spider genus Havaika Prószyński, 2001 (Araneae, Salticidae).

    PubMed

    Arnedo, Miquel A; Gillespie, Rosemary G

    2006-11-01

    Hotspot archipelagoes provide exceptional models for the study of the evolutionary process, due to the effects of isolation and topographical diversity in inducing the formation of unique biotic assemblages. In this paper, we examine the evolutionary patterns exhibited by the jumping spider genus Havaika Prószyński, 2001 in the Polynesian islands of the Hawaiian and Marquesas chains. To date, systematic research on Havaika has been seriously limited by the poor taxonomic knowledge on the group, which was based on a handful of specimens that showed continuous variability and lacked clear-cut diagnostic characters. Here, we circumvent this problem by inferring a phylogeny based on DNA sequences of several fragments including both mitochondrial (protein coding cytochrome oxidase I, NAD1 dehydrogenase, ribosomal 16S, and tRNA leu) and nuclear (internal transcribed spacer 2) genes, and a statistical morphological analyses of a large sample of specimens. Results suggest that the Marquesan and Hawaiian Havaika may be the result of independent colonizations. Furthermore, data provide little support for the standard "progression rule" (evolution in the direction of older to younger islands) in Hawaiian Islands. This may be explained by a recent arrival of the group: age estimates of the different lineages suggest that Havaika colonized the Hawaiian Islands after most of the extant islands were already formed. The lack of clear-cut diagnostic characters among species may also be explained by the recent origin of the group since molecular data do not provide any evidence of hybridization among lineages. Quantitative morphological data coupled with the phylogenetic information allow us to reevaluate the current limitation of Havaika taxonomy. Molecular data support the existence of at least four different evolutionary lineages that are further morphologically diagnosable. However, genealogical relationships are better predicted by geographical affinity (i.e. island) than by

  6. Catalogue of Texas spiders.

    PubMed

    Dean, David Allen

    2016-01-01

    This catalogue lists 1,084 species of spiders (three identified to genus only) in 311 genera from 53 families currently recorded from Texas and is based on the "Bibliography of Texas Spiders" published by Bea Vogel in 1970. The online list of species can be found at http://pecanspiders.tamu.edu/spidersoftexas.htm. Many taxonomic revisions have since been published, particularly in the families Araneidae, Gnaphosidae and Leptonetidae. Many genera in other families have been revised. The Anyphaenidae, Ctenidae, Hahniidae, Nesticidae, Sicariidae and Tetragnathidae were also revised. Several families have been added and others split up. Several genera of Corinnidae were transferred to Phrurolithidae and Trachelidae. Two genera from Miturgidae were transferred to Eutichuridae. Zoridae was synonymized under Miturgidae. A single species formerly in Amaurobiidae is now in the Family Amphinectidae. Some trapdoor spiders in the family Ctenizidae have been transferred to Euctenizidae. Gertsch and Mulaik started a list of Texas spiders in 1940. In a letter from Willis J. Gertsch dated October 20, 1982, he stated "Years ago a first listing of the Texas fauna was published by me based largely on Stanley Mulaik material, but it had to be abandoned because of other tasks." This paper is a compendium of the spiders of Texas with distribution, habitat, collecting method and other data available from revisions and collections. This includes many records and unpublished data (including data from three unpublished studies). One of these studies included 16,000 adult spiders belonging to 177 species in 29 families. All specimens in that study were measured and results are in the appendix. Hidalgo County has 340 species recorded with Brazos County at 323 and Travis County at 314 species. These reflect the amount of collecting in the area. PMID:27103878

  7. A new Agraecina spider species from the Balkan Peninsula (FYR Macedonia) (Araneae: Liocranidae).

    PubMed

    Deltshev, Christo; Wang, Chunxia

    2016-01-01

            Specimens were collected using pitfall traps. Coloration is described from alcohol-preserved specimens. Specimens were examined and measured using a Wild M5A stereomicroscope. Further details were studied and measured under an Olympus BX41 compound microscope. All drawings were made using a drawing apparatus attached to a Leica stereomicroscope. Male palps and female genitalia were examined and illustrated after they were dissected from the spiders' bodies. Photos were taken with an Olympus C7070 wide zoom digital camera mounted on an Olympus SZX12 stereomicroscope. The images were montaged using Helicon Focus image stacking software. Measurements of the legs are taken from the dorsal side. Total length of the body includes the chelicerae. All measurements were taken in mm. Abbreviations used in text include: AME, anterior median eyes; ALE, anterior lateral eyes; EM, embolus; MA, median apophysis; CD, copulatory duct; ST, spermatheca; fe, femur; pa, patella; ti, tibia; mt, metatarsus; p, prolateral; d, dorsal; r, retrolateral; v, ventral. Type specimens are deposited in the National Museum of Natural History (NMNHS), Sofia, Bulgaria. PMID:27395163

  8. Molecular insights into species phylogeny, biogeography, and morphological stasis in the ancient spider genus Hypochilus (Araneae: Hypochilidae).

    PubMed

    Hedin, M C

    2001-02-01

    The spider genus Hypochilus is currently restricted to cool, moist microhabitats in three widely separated montane regions of North America, providing an opportunity to study both deep (i.e., continental level) and shallow (within montane region) biogeographic history. Members of the genus also retain many plesiomorphic morphological characteristics, inviting the study of comparative rates of morphological evolution. In this paper, Hypochilus phylogeny and associated evolutionary problems are addressed using both new molecular (28S nDNA and CO1 mtDNA) and previously published (K. M. Catley, 1994, Am. Mus. Nov. 3088, 1-27) morphological data. Although the molecular data provide limited resolution of root placement within Hypochilus, most analyses are at least consistent with morphology-supported montane relationships of (Rockies (California, Appalachian)). The monophyly of Hypochilus species distributed in the California mountains is ambiguous, with several analyses indicating that this fauna may be paraphyletic with respect to a monophyletic Appalachian lineage. The montane regions differ in consistent ways in depths of both mitochondrial and nuclear phylogenetic divergence. Molecular clock analyses, in combination with arthropod-based mtDNA rate calibrations, suggest that the regional faunas are of different ages and that speciation in all faunas likely occurred prior to the Pleistocene. Limited intraspecific sampling reveals extraordinarily high levels of mtDNA cytochrome oxidase sequence divergence. These extreme divergences are most consistent with morphological stasis at the species level, despite preliminary evidence that Hypochilus taxa are characterized by fragmented population structures.

  9. Flow cytometric sexing of spider sperm reveals an equal sperm production ratio in a female-biased species

    PubMed Central

    Vanthournout, B.; Deswarte, K.; Hammad, H.; Bilde, T.; Lambrecht, B.; Hendrickx, F.

    2014-01-01

    Producing equal amounts of male and female offspring has long been considered an evolutionarily stable strategy. Nevertheless, exceptions to this general rule (i.e. male and female biases) are documented in many taxa, making sex allocation an important domain in current evolutionary biology research. Pinpointing the underlying mechanism of sex ratio bias is challenging owing to the multitude of potential sex ratio-biasing factors. In the dwarf spider, Oedothorax gibbosus, infection with the bacterial endosymbiont Wolbachia results in a female bias. However, pedigree analysis reveals that other factors influence sex ratio variation. In this paper, we investigate whether this additional variation can be explained by the unequal production of male- and female-determining sperm cells during sperm production. Using flow cytometry, we show that males produce equal amounts of male- and female-determining sperm cells; thus bias in sperm production does not contribute to the sex ratio bias observed in this species. This demonstrates that other factors such as parental genes suppressing endosymbiont effects and cryptic female choice might play a role in sex allocation in this species. PMID:24850893

  10. Visual search for tropical web spiders: the influence of plot length, sampling effort, and phase of the day on species richness.

    PubMed

    Pinto-Leite, C M; Rocha, P L B

    2012-12-01

    Empirical studies using visual search methods to investigate spider communities were conducted with different sampling protocols, including a variety of plot sizes, sampling efforts, and diurnal periods for sampling. We sampled 11 plots ranging in size from 5 by 10 m to 5 by 60 m. In each plot, we computed the total number of species detected every 10 min during 1 hr during the daytime and during the nighttime (0630 hours to 1100 hours, both a.m. and p.m.). We measured the influence of time effort on the measurement of species richness by comparing the curves produced by sample-based rarefaction and species richness estimation (first-order jackknife). We used a general linear model with repeated measures to assess whether the phase of the day during which sampling occurred and the differences in the plot lengths influenced the number of species observed and the number of species estimated. To measure the differences in species composition between the phases of the day, we used a multiresponse permutation procedure and a graphical representation based on nonmetric multidimensional scaling. After 50 min of sampling, we noted a decreased rate of species accumulation and a tendency of the estimated richness curves to reach an asymptote. We did not detect an effect of plot size on the number of species sampled. However, differences in observed species richness and species composition were found between phases of the day. Based on these results, we propose guidelines for visual search for tropical web spiders.

  11. Enoplognatha bryjai new species, a bizzare cobweb spider of the Pannonian swamps (Araneae, Theridiidae).

    PubMed

    Řezáč, Milan; Řezáčová, Veronika; Heneberg, Petr

    2016-01-01

    During faunistic research of reed beds associated with lakes in the Pannonian region of Czechia we found an Enoplognatha species with spectacular morphology of the male chelicerae. Despite this species being found in an arachnologically well researched area, and that the European species of the genus Enoplognatha have been recently revised (Bosmans & Van Keer 1999), it appears to be a new species. PMID:27515608

  12. A review of the Nearctic linyphiid spider Arcuphantes fragilis (Araneae, Linyphiidae) and closely related species.

    PubMed

    Ma, Shuangchun; Marusik, Yuri M; Tu, Lihong

    2016-01-01

    The Western Nearctic species Arcuphantes fragilis Chamberlin & Ivie, 1943 and several closely related species are reviewed. Seven species are recognized, including two new species: A. cavaticus Chamberlin & Ivie, 1943, A. decoratus Chamberlin & Ivie, 1943, A. fragilis Chamberlin & Ivie, 1943, A. dentatus n. sp., A. curvomarginatus n. sp., A. potteri Chamberlin & Ivie, 1943, and A. sylvaticus Chamberlin & Ivie, 1943. The female of A. decoratus is described for the first time. These seven species share a same genital type, distinguishing them from other congeners, with small differences among them. Illustrations for A. dentatus n. sp., SEM images and digital photographs for all seven species are presented. Descriptions of new species, redescriptions of known species and a key for the seven species are provided. PMID:27470863

  13. Protein composition correlates with the mechanical properties of spider ( Argiope trifasciata ) dragline silk.

    PubMed

    Marhabaie, Mohammad; Leeper, Thomas C; Blackledge, Todd A

    2014-01-13

    We investigated the natural variation in silk composition and mechanical performance of the orb-weaving spider Argiope trifasciata at multiple spatial and temporal scales in order to assess how protein composition contributes to the remarkable material properties of spider dragline silk. Major ampullate silk in orb-weaving spiders consists predominantly of two proteins (MaSp1 and MaSp2) with divergent amino acid compositions and functionally different microstructures. Adjusting the expression of these two proteins therefore provides spiders with a simple mechanism to alter the material properties of their silk. We first assessed the reliability and precision of the Waters AccQ-Tag amino acid composition analysis kit for determining the amino acid composition of small quantities of spider silk. We then tested how protein composition varied within single draglines, across draglines spun by the same spider on different days, and finally between spiders. Then, we correlated chemical composition with the material properties of dragline silk. Overall, we found that the chemical composition of major ampullate silk was in general homogeneous among individuals of the same population. Variation in chemical composition was not detectable within silk spun by a single spider on a single day. However, we found that variation within a single spider's silk across different days could, in rare instances, be greater than variation among individual spiders. Most of the variation in silk composition in our investigation resulted from a small number of outliers (three out of sixteen individuals) with a recent history of stress, suggesting stress affects silk production process in orb web spiders. Based on reported sequences for MaSp genes, we developed a gene expression model showing the covariation of the most abundant amino acids in major ampullate silk. Our gene expression model supports that dragline silk composition was mostly determined by the relative abundance of MaSp1 and Ma

  14. Spider leg autotomy induced by prey venom injection: An adaptive response to “pain”?*

    PubMed Central

    Eisner, Thomas; Camazine, Scott

    1983-01-01

    Field observations showed orb-weaving spiders (Argiope spp.) to undergo leg autotomy if they are stung in a leg by venomous insect prey (Phymata fasciata). The response occurs within seconds, before the venom can take lethal action by spread to the body of the spiders. Autotomy is induced also by honeybee venom and wasp venom, as well as by several venom components (serotonin, histamine, phospholipase A2, melittin) known to be responsible for the pain characteristically elicited by venom injection in humans. The sensing mechanism by which spiders detect injected harmful chemicals such as venoms therefore may be fundamentally similar to the one in humans that is coupled with the perception of pain. Images PMID:16593325

  15. Description of eleven new species of the goblin spider genus Neoxyphinus Birabén, 1953 (Araneae, Oonopidae).

    PubMed

    Moss, Daniella F; Feitosa, Níthomas M; Bonaldo, Alexandre B; Ruiz, Gustavo R S

    2016-01-01

    The spiders of the genus Neoxyphinus Birabén differ from those of other oonopid genera by the male endites with an api-cal, retrolateral excavation bearing a subapical tooth-like apophysis and, in females, by the ellipsoid genital atrium, with angular lateral margins. In this paper, eleven new species of the genus are described, mainly from northern South America: N. amazonicus Moss & Feitosa, sp. nov. (♂♀) from Colombia and Brazil; N. macuna Moss & Ruiz, sp. nov. (♂♀), N. tuparro Moss & Ruiz, sp. nov. (♂) and N. pure Moss & Bonaldo, sp. nov. (♂♀) from Colombia; N. yekuana Moss & Feitosa, sp. nov. (♂♀), N. trujillo Moss & Bonaldo, sp. nov. (♂♀), N. yacambu Moss & Feitosa, sp. nov. (♂) and N. saarineni Moss & Bonaldo, sp. nov. (♂) from Venezuela; N. inca Moss & Ruiz, sp. nov. (♂♀) from Peru; N. beni Moss & Feitosa, sp. nov. (♂♀) from Bolivia; and N. coca Moss & Feitosa, sp. nov. (♂♀) from Ecuador. PMID:27394576

  16. Biogeography and diversification of hermit spiders on Indian Ocean islands (Nephilidae: Nephilengys).

    PubMed

    Kuntner, Matjaž; Agnarsson, Ingi

    2011-05-01

    , throughout the archipelago. Instead, we diagnose three Nephilengys species: Nephilengys livida (Vinson, 1863) from Madagascar and Comoros, N. borbonica (Vinson, 1863) from Réunion, and Nephilengys dodo new species from Mauritius. Nephilengys followed a colonization route to Madagascar from Africa, and on through to the Mascarenes, where it speciated on isolated islands. The related golden orb-weaving spiders, genus Nephila, have followed the same colonization route, but Nephila shows shallower divergencies, implying recent colonization, or a moderate level of gene flow across the archipelago preventing speciation. Unlike their synanthropic congeners, N. borbonica and N. dodo are confined to pristine island forests and their discovery calls for evaluation of their conservation status.

  17. Nesticus baeticus sp. n., a new troglobitic spider species from south-west Europe (Araneae, Nesticidae)

    PubMed Central

    López-Pancorbo, Alberto; Ribera, Carles

    2011-01-01

    Abstract A new troglobitic species, Nesticus baeticus sp. n. (♂♀), inhabiting the karst landscapes of the high part of the Cazorla, Segura and Las Villas Natural Park (NE Jaén, Spain) where it has been found in 8 caves is diagnosed and described, its distribution and habitat are also analyzed.The new species belongs to the Iberian species group that includes Nesticus luquei, Nesticus lusitanicus and Nesticus murgis. Evolutionary relationships of the Iberian Nesticus species are discussed on the basis of morphological and molecular data (cox1 and rrnL). PMID:21594081

  18. Characterization of the complete mitogenomes of two Neoscona spiders (Araneae: Araneidae) and its phylogenetic implications.

    PubMed

    Wang, Zheng-Liang; Li, Chao; Fang, Wen-Yuan; Yu, Xiao-Ping

    2016-09-30

    The complete mitogenomes of two orb-weaving spiders Neoscona doenitzi and Neoscona nautica were determined and a comparative mitogenomic analysis was performed to depict evolutionary trends of spider mitogenomes. The circular mitogenomes are 14,161bp with A+T content of 74.6% in N. doenitzi and 14,049bp with A+T content of 78.8% in N. nautica, respectively. Both mitogenomes contain a standard set of 37 genes typically presented in metazoans. Gene content and orientation are identical to all previously sequenced spider mitogenomes, while gene order is rearranged by tRNAs translocation when compared with the putative ancestral gene arrangement pattern presented by Limulus polyphemus. A comparative mitogenomic analysis reveals that the nucleotide composition bias is obviously divergent between spiders in suborder Opisthothelae and Mesothelae. The loss of D-arm in the trnS(UCN) among all of Opisthothelae spiders highly suggested that this common feature is a synapomorphy for entire suborder Opisthothelae. Moreover, the trnS(AGN) in araneoids preferred to use TCT as an anticodon rather than the typical anticodon GCT. Phylogenetic analysis based on the 13 protein-coding gene sequences consistently yields trees that nest the two Neoscona spiders within Araneidae and recover superfamily Araneoidea as a monophyletic group. The molecular information acquired from the results of this study should be very useful for future research on mitogenomic evolution and genetic diversities in spiders. PMID:27259661

  19. Catalogue of Texas spiders

    PubMed Central

    Dean, David Allen

    2016-01-01

    Abstract This catalogue lists 1,084 species of spiders (three identified to genus only) in 311 genera from 53 families currently recorded from Texas and is based on the “Bibliography of Texas Spiders” published by Bea Vogel in 1970. The online list of species can be found at http://pecanspiders.tamu.edu/spidersoftexas.htm. Many taxonomic revisions have since been published, particularly in the families Araneidae, Gnaphosidae and Leptonetidae. Many genera in other families have been revised. The Anyphaenidae, Ctenidae, Hahniidae, Nesticidae, Sicariidae and Tetragnathidae were also revised. Several families have been added and others split up. Several genera of Corinnidae were transferred to Phrurolithidae and Trachelidae. Two genera from Miturgidae were transferred to Eutichuridae. Zoridae was synonymized under Miturgidae. A single species formerly in Amaurobiidae is now in the Family Amphinectidae. Some trapdoor spiders in the family Ctenizidae have been transferred to Euctenizidae. Gertsch and Mulaik started a list of Texas spiders in 1940. In a letter from Willis J. Gertsch dated October 20, 1982, he stated “Years ago a first listing of the Texas fauna was published by me based largely on Stanley Mulaik material, but it had to be abandoned because of other tasks.” This paper is a compendium of the spiders of Texas with distribution, habitat, collecting method and other data available from revisions and collections. This includes many records and unpublished data (including data from three unpublished studies). One of these studies included 16,000 adult spiders belonging to 177 species in 29 families. All specimens in that study were measured and results are in the appendix. Hidalgo County has 340 species recorded with Brazos County at 323 and Travis County at 314 species. These reflect the amount of collecting in the area. PMID:27103878

  20. From Nano to Micro: Importance of Structure and Architecture in Spider Silk Adhesives

    NASA Astrophysics Data System (ADS)

    Sahni, Vasav; Dhinojwala, Ali

    2012-02-01

    Spiders have developed outstanding adhesives over millions of years of evolution for prey capture and locomotion. We show that the structure and architecture of these adhesives play an important role in the adhesion. The adhesive produced by orb-weaving spiders to capture prey (viscid glue) is laid on a pair of silk fibers as micron-size glue drops composed of salts and glycoproteins. By stretching single drops, we show that viscid glue behaves like a viscoelastic solid and that elasticity is critical in enhancing adhesion caused by specific adhesive ligands by over 100 times. Comparing viscid glue with gumfoot glue, the glue produced by cob-weavers, the evolutionary descendants of orb-weavers, showed that, in spite of being produced in homologous aggregate glands, gumfoot glue behaves like a viscoelastic liquid. Moreover, gumfoot glue is humidity-resistant and viscid glue is humidity-sensitive. We use a synthetic strategy to spin beads-on-a-string (BOAS) architecture to mimic the adhesive properties of spider silk. Using these mimic threads, we show that the BOAS structure adheres more than a cylindrical structure during contact (collision of prey) and during separation (escape attempt of prey). These results inspire design of novel tunable adhesives.

  1. The Complete Mitochondrial Genomes of Six Species of Tetranychus Provide Insights into the Phylogeny and Evolution of Spider Mites

    PubMed Central

    Chen, Da-Song; Jin, Peng-Yu; Zhang, Kai-Jun; Ding, Xiu-Lei; Yang, Si-Xia; Ju, Jia-Fei; Zhao, Jing-Yu; Hong, Xiao-Yue

    2014-01-01

    Many spider mites belonging to the genus Tetranychus are of agronomical importance. With limited morphological characters, Tetranychus mites are usually identified by a combination of morphological characteristics and molecular diagnostics. To clarify their molecular evolution and phylogeny, the mitochondrial genomes of the green and red forms of Tetranychus urticae as well as T. kanzawai, T. ludeni, T. malaysiensis, T. phaselus, T. pueraricola were sequenced and compared. The seven mitochondrial genomes are typical circular molecules of about 13,000 bp encoding and they are composed of the complete set of 37 genes that are usually found in metazoans. The order of the mitochondrial (mt) genes is the same as that in the mt genomes of Panonychus citri and P. ulmi, but very different from that in other Acari. The J-strands of the mitochondrial genomes have high (∼84%) A+T contents, negative GC-skews and positive AT-skews. The nucleotide sequence of the cox1 gene, which is commonly used as a taxon barcode and molecular marker, is more highly conserved than the nucleotide sequences of other mitochondrial genes in these seven species. Most tRNA genes in the seven genomes lose the D-arm and/or the T-arm. The functions of these tRNAs need to be evaluated. The mitochondrial genome of T. malaysiensis differs from the other six genomes in having a slightly smaller genome size, a slight difference in codon usage, and a variable loop in place of the T-arm of some tRNAs by a variable loop. A phylogenic analysis shows that T. malaysiensis first split from other Tetranychus species and that the clade of the family Tetranychoidea occupies a basal position in the Trombidiformes. The mt genomes of the green and red forms of T. urticae have limited divergence and short evolutionary distance. PMID:25329165

  2. The complete mitochondrial genomes of six species of Tetranychus provide insights into the phylogeny and evolution of spider mites.

    PubMed

    Chen, Da-Song; Jin, Peng-Yu; Zhang, Kai-Jun; Ding, Xiu-Lei; Yang, Si-Xia; Ju, Jia-Fei; Zhao, Jing-Yu; Hong, Xiao-Yue

    2014-01-01

    Many spider mites belonging to the genus Tetranychus are of agronomical importance. With limited morphological characters, Tetranychus mites are usually identified by a combination of morphological characteristics and molecular diagnostics. To clarify their molecular evolution and phylogeny, the mitochondrial genomes of the green and red forms of Tetranychus urticae as well as T. kanzawai, T. ludeni, T. malaysiensis, T. phaselus, T. pueraricola were sequenced and compared. The seven mitochondrial genomes are typical circular molecules of about 13,000 bp encoding and they are composed of the complete set of 37 genes that are usually found in metazoans. The order of the mitochondrial (mt) genes is the same as that in the mt genomes of Panonychus citri and P. ulmi, but very different from that in other Acari. The J-strands of the mitochondrial genomes have high (∼ 84%) A+T contents, negative GC-skews and positive AT-skews. The nucleotide sequence of the cox1 gene, which is commonly used as a taxon barcode and molecular marker, is more highly conserved than the nucleotide sequences of other mitochondrial genes in these seven species. Most tRNA genes in the seven genomes lose the D-arm and/or the T-arm. The functions of these tRNAs need to be evaluated. The mitochondrial genome of T. malaysiensis differs from the other six genomes in having a slightly smaller genome size, a slight difference in codon usage, and a variable loop in place of the T-arm of some tRNAs by a variable loop. A phylogenic analysis shows that T. malaysiensis first split from other Tetranychus species and that the clade of the family Tetranychoidea occupies a basal position in the Trombidiformes. The mt genomes of the green and red forms of T. urticae have limited divergence and short evolutionary distance.

  3. Pleistocene niche stability and lineage diversification in the subtropical spider Araneus omnicolor (Araneidae).

    PubMed

    Peres, Elen A; Sobral-Souza, Thadeu; Perez, Manolo F; Bonatelli, Isabel A S; Silva, Daniel P; Silva, Márcio J; Solferini, Vera N

    2015-01-01

    The influence of Quaternary climate oscillations on the diversification of the South American fauna is being increasingly explored. However, most of these studies have focused on taxa that are endemic to tropical environments, and relatively few have treated organisms restricted to subtropical biomes. Here we used an integrative phylogeographical framework to investigate the effects of these climate events on the ecological niche and genetic patterns of the subtropical orb-weaver spider Araneus omnicolor (Araneidae). We analyzed the mitochondrial (Cytochrome Oxidase I, COI) and nuclear (Internal Transcribed Subunit II, ITS2) DNA of 130 individuals throughout the species' range, and generated distribution models in three different climate scenarios [present, Last Glacial Maximum (LGM), and Last Interglacial Maximum (LIG)]. Additionally, we used an Approximate Bayesian Computation (ABC) approach to compare possible demographic scenarios and select the hypothesis that better explains the genetic patterns of A. omnicolor. We obtained high haplotype diversity but low nucleotide variation among sequences. The population structure and demographic analyses showed discrepancies between markers, suggesting male-biased dispersal in the species. The time-calibrated COI phylogenetic inference showed a recent diversification of lineages (Middle/Late Pleistocene), while the paleoclimate modeling indicated niche stability since ~120 Kya. The ABC results agreed with the niche models, supporting a panmictic population as the most likely historical scenario for the species. These results indicate that A. omnicolor experienced no niche or population reductions during the Late Pleistocene, despite the intense landscape modifications that occurred in the subtropical region, and that other factors beside LGM and LIG climate oscillations might have contributed to the demographic history of this species. This pattern may be related to the high dispersal ability and wide environmental

  4. Phylogeography of a successful aerial disperser: the golden orb spider Nephila on Indian Ocean islands

    PubMed Central

    2011-01-01

    Background The origin and diversification patterns of lineages across the Indian Ocean islands are varied due to the interplay of the complex geographic and geologic island histories, the varying dispersal abilities of biotas, and the proximity to major continental landmasses. Our aim was to reconstruct phylogeographic history of the giant orbweaving spider (Nephila) on western Indian Ocean islands (Madagascar, Mayotte, Réunion, Mauritius, Rodrigues), to test its origin and route of dispersal, and to examine the consequences of good dispersal abilities for colonization and diversification, in comparison with related spiders (Nephilengys) inhabiting the same islands, and with other organisms known for over water dispersal. We used mitochondrial (COI) and nuclear (ITS2) markers to examine phylogenetic and population genetic patterns in Nephila populations and species. We employed Bayesian and parsimony methods to reconstruct phylogenies and haplotype networks, respectively, and calculated genetic distances, fixation indices, and estimated clade ages under a relaxed clock model. Results Our results suggest an African origin of Madagascar Nephila inaurata populations via Cenozoic dispersal, and the colonization of the Mascarene islands from Madagascar. We find evidence of gene flow across Madagascar and Comoros. The Mascarene islands share a common 'ancestral' COI haplotype closely related to those found on Madagascar, but itself absent, or as yet unsampled, from Madagascar. Each island has one or more unique haplotypes related to the ancestral Mascarene haplotype. The Indian Ocean N. inaurata are genetically distinct from the African populations. Conclusions Nephila spiders colonized Madagascar from Africa about 2.5 (0.6-5.3) Ma. Our results are consistent with subsequent, recent and rapid, colonization of all three Mascarene islands. On each island, however, we detected unique haplotypes, consistent with a limited gene flow among the islands subsequent to

  5. New genera, new species and redescriptions of Australian jumping spiders
    (Araneae: Salticidae).

    PubMed

    Richardson, Barry J

    2016-01-01

    A number of Australian species have been placed in the wrong, often non-Australian, genera. Some of these problems have been corrected here, by transfer or establishment of new genera. Several new species discovered during the course of the work are also described. Marptusa jovialis L. Koch, 1879 and Marptusa bracteata L. Koch, 1879 are transferred to Apricia gen. nov. Apricia longipalpis sp. nov. is also described from Australia. The study of the Australian species presently included in Trite Simon 1885 showed that this genus does not occur in mainland Australia. Hence, Marptusa vulpecula Thorell, 1881 is transferred to Capeyorkia gen. nov., while Marptusa longula Thorell, 1881 is transferred to Evarcha Simon, 1902. The only previously described 'Australian' species to remain in Trite is Trite concinna Rainbow, 1920, from Lord Howe Island and Norfolk Island in the Pacific, while Trite grayi sp. nov., also from Lord Howe Island, is described here. Trite concinna Rainbow 1920 is redescribed. Most specimens previous listed as this species from Lord Howe Island (including most of the syntype series) belong in Ancepitilobus howensis gen. nov. et sp. nov. Clynotis severus (L. Koch, 1879) is the solitary species that remains in Clynotis Simon, 1901, with the remainder of the mainland species being transferred to Pungalina Richardson, 2013: P. albobarbata (L. Koch, 1879) comb. nov., P. semiatra (L. Koch, 1879) comb. nov. and P. semiferruginea (L. Koch, 1879) comb. nov. Pungalina plurilineata sp. nov. and Pungalina waldockae sp. nov. are also described from Australia. Clynotis gratiosa from Lord Howe Island is formally transferred to Tara Peckham & Peckham, 1886, as suggested previously. Tara gratiosa (Rainbow, 1920) is redescribed. Finally, three names, Gangus longulus Simon, 1902, Trite ornata Rainbow, 1915 and Plexippus albopilosus Keyserling, 1883, are considered species inquirendae, due to the state or loss of type material.

  6. Nine new species of the spider genus Pireneitega Kishida, 1955 (Agelenidae, Coelotinae) from Xinjiang, China.

    PubMed

    Zhang, Xiaoqing; Zhao, Zhe; Zheng, Guo; Li, Shuqiang

    2016-01-01

    Nine new Pireneitega species collected from Xinjiang, China are described as new to science: Pireneitega burqinensis sp. n. (♂♀), Pireneitega fuyunensis sp. n. (♂♀), Pireneitega gongliuensis sp. n. (♂♀), Pireneitega huochengensis sp. n. (♂♀), Pireneitega lini sp. n. (♀), Pireneitega liui sp. n. (♂♀), Pireneitega wensuensis sp. n. (♂), Pireneitega wui sp. n. (♂) and Pireneitega yaoi sp. n. (♀). DNA barcodes were obtained for all these species for future use. PMID:27551187

  7. New genera, new species and redescriptions of Australian jumping spiders
    (Araneae: Salticidae).

    PubMed

    Richardson, Barry J

    2016-01-01

    A number of Australian species have been placed in the wrong, often non-Australian, genera. Some of these problems have been corrected here, by transfer or establishment of new genera. Several new species discovered during the course of the work are also described. Marptusa jovialis L. Koch, 1879 and Marptusa bracteata L. Koch, 1879 are transferred to Apricia gen. nov. Apricia longipalpis sp. nov. is also described from Australia. The study of the Australian species presently included in Trite Simon 1885 showed that this genus does not occur in mainland Australia. Hence, Marptusa vulpecula Thorell, 1881 is transferred to Capeyorkia gen. nov., while Marptusa longula Thorell, 1881 is transferred to Evarcha Simon, 1902. The only previously described 'Australian' species to remain in Trite is Trite concinna Rainbow, 1920, from Lord Howe Island and Norfolk Island in the Pacific, while Trite grayi sp. nov., also from Lord Howe Island, is described here. Trite concinna Rainbow 1920 is redescribed. Most specimens previous listed as this species from Lord Howe Island (including most of the syntype series) belong in Ancepitilobus howensis gen. nov. et sp. nov. Clynotis severus (L. Koch, 1879) is the solitary species that remains in Clynotis Simon, 1901, with the remainder of the mainland species being transferred to Pungalina Richardson, 2013: P. albobarbata (L. Koch, 1879) comb. nov., P. semiatra (L. Koch, 1879) comb. nov. and P. semiferruginea (L. Koch, 1879) comb. nov. Pungalina plurilineata sp. nov. and Pungalina waldockae sp. nov. are also described from Australia. Clynotis gratiosa from Lord Howe Island is formally transferred to Tara Peckham & Peckham, 1886, as suggested previously. Tara gratiosa (Rainbow, 1920) is redescribed. Finally, three names, Gangus longulus Simon, 1902, Trite ornata Rainbow, 1915 and Plexippus albopilosus Keyserling, 1883, are considered species inquirendae, due to the state or loss of type material. PMID:27395145

  8. Pholcid spiders (Araneae: Pholcidae) from northern Vietnam, with descriptions of nineteen new species.

    PubMed

    Yao, Zhiyuan; Pham, Dinh Sac; Li, Shuqiang

    2015-01-15

    Five genera and 26 species belonging to two subfamilies Arteminae Simon, 1893 (one genus and one species) and Pholcinae C.L. Koch, 1850 (four genera and 25 species) are reported from northern Vietnam, including 19 new species of three genera: Belisana babensis sp. nov. (male, female; Bac Kan), B. cheni sp. nov. (male, female; Bac Kan), B. clavata sp. nov. (male; Ha Giang), B. curva sp. nov. (male; Vinh Phuc), B. decora sp. nov. (male, female; Ninh Binh), B. halongensis sp. nov. (male; Quang Ninh), B. phungae sp. nov. (male, female; Bac Kan), B. pisinna sp. nov. (male; Quang Ninh), B. triangula sp. nov. (male; Phu Tho), B. vietnamensis sp. nov. (male, female; Ninh Binh), B. zhengi sp. nov. (male; Vinh Phuc), Khorata dangi sp. nov. (male; Bac Kan), K. huberi sp. nov. (male, female; Bac Kan), K. protumida sp. nov. (male, female; Quang Binh), Pholcus bifidus sp. nov. (male, female; Quang Binh), P. caecus sp. nov. (male, female; Quang Binh), P. hochiminhi sp. nov. (male, female; Quang Ninh), P. phami sp. nov. (male, female; Bac Kan), and P. zhaoi sp. nov. (male; Ninh Binh). One genus Khorata Huber, 2005 and five species Belisana schwendingeri Huber, 2005, B. sepaku Huber, 2005, Khorata digitata Yao & Li, 2010, Leptopholcus podophthalmus (Simon, 1893), and Pholcus bangfai Huber, 2011 are reported from Vietnam for the first time. Additional new records are given for two species Leptopholcus huongson Huber, 2011 and Physocyclus globosus (Taczanowski, 1874). 

  9. Red List of spiders (araneae) of the Wadden Sea Area

    NASA Astrophysics Data System (ADS)

    Vangsgård, C.; Reinke, H.-D.; Schultz, W.; van Helsdingen, P. J.

    1996-10-01

    In the Wadden Sea, in total, 55 species of spiders are threatened in at least one subregion. Of these, 50 species are threatened in the entire area and are therefore placed on the trilateral Red List. According to the present knowledge, no species of the listed spiders are extinct in the entire Wadden Sea area. The status of 3 species of spiders is (probably) critical; 12 species are endangered; the status of 30 species is (probably) vulnerable and of 6 species susceptible.

  10. Cheiracanthium ilicis sp. n. (Araneae, Eutichuridae), a novel spider species associated with Holm Oaks (Quercus ilex).

    PubMed

    Morano, Eduardo; Bonal, Raul

    2016-01-01

    We describe a novel species Cheiracanthium ilicis sp. n. (Araneae, Eutichuridae) collected in the province of Toledo (Central Spain). It was found during a systematic sampling campaign carried out in an agricultural landscape with isolated Holm oaks Quercus ilex and small forest patches. Its morphology and affinities with other species of the genus are discussed. Furthermore, one mitochondrial gene was sequenced to confirm species membership and its differentiation from other Cheiracanthium species. The molecular phylogenies based on mitochondrial and nuclear genes showed a close relationship of Cheiracanthium ilicis sp. n. with Cheiracanthium inclusum and Cheiracanthium mildei, with which it also shares morphological similarities. Nonetheless, the sparse sampling of the phylogeny, due to the low number of sequences available, impedes drawing any definitive conclusion about these relationships; it is first necessary to perform an extensive review of the genus worldwide and more thorough phylogenies. Cheiracanthium ilicis sp. n. also shares certain ecological and phenological characteristics with Cheiracanthium inclusum and Cheiracanthium mildei. Like them, Cheiracanthium ilicis sp. n. is an obligate tree dweller that prefers a tree canopy habitat and reproduces primarily in late spring and summer. From a conservation perspective, the present study suggests the need to preserve isolated trees in agricultural landscapes. They are not only the refuge of common forest organisms but also of novel species yet to be discovered. PMID:27551185

  11. Cheiracanthium ilicis sp. n. (Araneae, Eutichuridae), a novel spider species associated with Holm Oaks (Quercus ilex)

    PubMed Central

    Morano, Eduardo; Bonal, Raul

    2016-01-01

    Abstract We describe a novel species Cheiracanthium ilicis sp. n. (Araneae, Eutichuridae) collected in the province of Toledo (Central Spain). It was found during a systematic sampling campaign carried out in an agricultural landscape with isolated Holm oaks Quercus ilex and small forest patches. Its morphology and affinities with other species of the genus are discussed. Furthermore, one mitochondrial gene was sequenced to confirm species membership and its differentiation from other Cheiracanthium species. The molecular phylogenies based on mitochondrial and nuclear genes showed a close relationship of Cheiracanthium ilicis sp. n. with Cheiracanthium inclusum and Cheiracanthium mildei, with which it also shares morphological similarities. Nonetheless, the sparse sampling of the phylogeny, due to the low number of sequences available, impedes drawing any definitive conclusion about these relationships; it is first necessary to perform an extensive review of the genus worldwide and more thorough phylogenies. Cheiracanthium ilicis sp. n. also shares certain ecological and phenological characteristics with Cheiracanthium inclusum and Cheiracanthium mildei. Like them, Cheiracanthium ilicis sp. n. is an obligate tree dweller that prefers a tree canopy habitat and reproduces primarily in late spring and summer. From a conservation perspective, the present study suggests the need to preserve isolated trees in agricultural landscapes. They are not only the refuge of common forest organisms but also of novel species yet to be discovered. PMID:27551185

  12. Venomous Spiders

    MedlinePlus

    ... Monthly Review - Insects bites, stings cause thousands of workplace injuries ). Spiders are usually not aggressive and most bites ... Exposures and Effects NIOSH Homepage NIOSH A-Z Workplace Safety & Health Topics Publications and Products Programs Contact NIOSH ...

  13. Biphasic activity of a jumping spider.

    PubMed

    Okuyama, Toshinori

    2011-01-01

    Individual variation is a ubiquitous and important factor that affects ecological dynamics. This study examined individual variation in the nest-use pattern of the jumping spider Phidippus audax. Although the jumping spider is a diurnal species, field observations in this study revealed that the majority of individuals remained in their nests during the day. An accompanying examination of the hunger level of the spiders revealed that spiders that remained in nests were more starved than those observed outside nests. If spiders actively forage when they are starved, as has been suggested by previous studies, one would expect to see the opposite trend (i.e., spiders that remained in nests are more satiated). Thus, the pattern observed in the field contradicts the known behavioral pattern of the spiders. An individual-based model was used to investigate the behavioral mechanism of the spider and the discrepancy found in the observations. A basic assumption of the model is that spiders possess distinct inactive and active phases (biphasic activity pattern), and transitions between the two phases are regulated by the hunger level of the spider. Data from a laboratory experiment were used to examine the assumptions of the model partially. The model was able to capture patterns observed in the data, suggesting that the pattern of transitions in biphasic activity is an important trait of the foraging behavior of the jumping spider. PMID:21085925

  14. Biphasic activity of a jumping spider

    NASA Astrophysics Data System (ADS)

    Okuyama, Toshinori

    2011-01-01

    Individual variation is a ubiquitous and important factor that affects ecological dynamics. This study examined individual variation in the nest-use pattern of the jumping spider Phidippus audax. Although the jumping spider is a diurnal species, field observations in this study revealed that the majority of individuals remained in their nests during the day. An accompanying examination of the hunger level of the spiders revealed that spiders that remained in nests were more starved than those observed outside nests. If spiders actively forage when they are starved, as has been suggested by previous studies, one would expect to see the opposite trend (i.e., spiders that remained in nests are more satiated). Thus, the pattern observed in the field contradicts the known behavioral pattern of the spiders. An individual-based model was used to investigate the behavioral mechanism of the spider and the discrepancy found in the observations. A basic assumption of the model is that spiders possess distinct inactive and active phases (biphasic activity pattern), and transitions between the two phases are regulated by the hunger level of the spider. Data from a laboratory experiment were used to examine the assumptions of the model partially. The model was able to capture patterns observed in the data, suggesting that the pattern of transitions in biphasic activity is an important trait of the foraging behavior of the jumping spider.

  15. New species, new records and re-description of spider mites (Acari: Tetranychidae) from India.

    PubMed

    Zeity, Mahran; Srinivasa, N; Gowda, C Chinnamade

    2016-01-01

    Two species of Tetranychidae (Acari), Oligonychus neotylus sp. nov. from Zea mays and Pennisetum purpureum (Poaceae) and Tetranychus hirsutus sp. nov. from Gymnema sylvestre R. Br. (Apocynaceae) are described from Karnataka state, south India. Tetranychus bambusae Wang and Ma is recorded for the first time from India and re-described. Four other species are reported for the first time from India viz., Oligonychus coniferarum (McGregor), Oligonychus duncombei Meyer, Tetranychus marianae McGregor and Tetranychus okinawanus Ehara from Cupressus sp., an undetermined grass, Centrosema pubescens and Adenium obesum, respectively. PMID:27394311

  16. Nine new species of the spider genus Pireneitega Kishida, 1955 (Agelenidae, Coelotinae) from Xinjiang, China

    PubMed Central

    Zhang, Xiaoqing; Zhao, Zhe; Zheng, Guo; Li, Shuqiang

    2016-01-01

    Abstract Nine new Pireneitega species collected from Xinjiang, China are described as new to science: Pireneitega burqinensis sp. n. (♂♀), Pireneitega fuyunensis sp. n. (♂♀), Pireneitega gongliuensis sp. n. (♂♀), Pireneitega huochengensis sp. n. (♂♀), Pireneitega lini sp. n. (♀), Pireneitega liui sp. n. (♂♀), Pireneitega wensuensis sp. n. (♂), Pireneitega wui sp. n. (♂) and Pireneitega yaoi sp. n. (♀). DNA barcodes were obtained for all these species for future use. PMID:27551187

  17. Three new spider species of the genus Pholcus from the Taihang Mountains of China (Araneae, Pholcidae)

    PubMed Central

    Zhang, Bao-Shi; Zhang, Feng; Liu, Jing-Ze

    2016-01-01

    Abstract In this study, three new species belonging to the genus Pholcus, collected from a forest of the Taihang Mountains, P. R. China, are described under the names of Pholcus papillatus sp. n. (male, female), Pholcus curvus sp. n. (male, female) and Pholcus auricularis sp. n. (male, female). PMID:27408600

  18. Pleistocene Niche Stability and Lineage Diversification in the Subtropical Spider Araneus omnicolor (Araneidae)

    PubMed Central

    Peres, Elen A.; Sobral-Souza, Thadeu; Perez, Manolo F.; Bonatelli, Isabel A. S.; Silva, Daniel P.; Silva, Márcio J.; Solferini, Vera N.

    2015-01-01

    The influence of Quaternary climate oscillations on the diversification of the South American fauna is being increasingly explored. However, most of these studies have focused on taxa that are endemic to tropical environments, and relatively few have treated organisms restricted to subtropical biomes. Here we used an integrative phylogeographical framework to investigate the effects of these climate events on the ecological niche and genetic patterns of the subtropical orb-weaver spider Araneus omnicolor (Araneidae). We analyzed the mitochondrial (Cytochrome Oxidase I, COI) and nuclear (Internal Transcribed Subunit II, ITS2) DNA of 130 individuals throughout the species’ range, and generated distribution models in three different climate scenarios [present, Last Glacial Maximum (LGM), and Last Interglacial Maximum (LIG)]. Additionally, we used an Approximate Bayesian Computation (ABC) approach to compare possible demographic scenarios and select the hypothesis that better explains the genetic patterns of A. omnicolor. We obtained high haplotype diversity but low nucleotide variation among sequences. The population structure and demographic analyses showed discrepancies between markers, suggesting male-biased dispersal in the species. The time-calibrated COI phylogenetic inference showed a recent diversification of lineages (Middle/Late Pleistocene), while the paleoclimate modeling indicated niche stability since ~120 Kya. The ABC results agreed with the niche models, supporting a panmictic population as the most likely historical scenario for the species. These results indicate that A. omnicolor experienced no niche or population reductions during the Late Pleistocene, despite the intense landscape modifications that occurred in the subtropical region, and that other factors beside LGM and LIG climate oscillations might have contributed to the demographic history of this species. This pattern may be related to the high dispersal ability and wide environmental

  19. More on the spider genus Xeropigo O.P.-Cambridge (Araneae, Corinnidae, Corinninae): seven new species and new records from Brazil.

    PubMed

    Carvalho, Leonardo S; Shimano, Yulie; Candiani, David F; Bonaldo, Alexandre B

    2016-01-01

    Seven new species of the spider genus Xeropigo O. P.-Cambridge are described from Brazil, increasing the genus member list up to 16 species. X. piripiri n. sp., X. aitatu n. sp., and X. cajuina n. sp. are described from the state of Piauí. X. crispim n. sp. is described from the states of Ceará, Piauí, and Maranhão. X. oxente n. sp. is described from the state of Rio Grande do Norte. X. canga n. sp. is described from the state of Minas Gerais. X. ufo n. sp. is described from the state of Mato Grosso. The geographical distribution of X. tridentiger, X. camilae, X. pachitea, and X. perene is updated. A key to all species of Xeropigo is presented and possible relationships among all species of the genus are discussed. PMID:27395095

  20. More on the spider genus Xeropigo O.P.-Cambridge (Araneae, Corinnidae, Corinninae): seven new species and new records from Brazil.

    PubMed

    Carvalho, Leonardo S; Shimano, Yulie; Candiani, David F; Bonaldo, Alexandre B

    2016-05-17

    Seven new species of the spider genus Xeropigo O. P.-Cambridge are described from Brazil, increasing the genus member list up to 16 species. X. piripiri n. sp., X. aitatu n. sp., and X. cajuina n. sp. are described from the state of Piauí. X. crispim n. sp. is described from the states of Ceará, Piauí, and Maranhão. X. oxente n. sp. is described from the state of Rio Grande do Norte. X. canga n. sp. is described from the state of Minas Gerais. X. ufo n. sp. is described from the state of Mato Grosso. The geographical distribution of X. tridentiger, X. camilae, X. pachitea, and X. perene is updated. A key to all species of Xeropigo is presented and possible relationships among all species of the genus are discussed.

  1. Composition and Function of Spider Glues Maintained During the Evolution of Cobwebs.

    PubMed

    Jain, Dharamdeep; Zhang, Ci; Cool, Lydia Rose; Blackledge, Todd A; Wesdemiotis, Chrys; Miyoshi, Toshikazu; Dhinojwala, Ali

    2015-10-12

    Capture silks are an interesting class of biological glues that help spiders subdue their prey. Viscid capture silk produced by the orb web spiders is a combination of hygroscopic salts that aid in water uptake and interact with adhesive glycoproteins to make them soft and sticky. The orb was a stepping stone to the evolution of new web types, but little is known about the adhesives in these webs. For instance, cobweb spiders evolved from orb-weaving ancestors and utilize glue in specialized sticky gumfoot threads rather than an elastic spiral. Early investigation suggests that gumfoot adhesives are quite different viscid glues because they lack a visible glycoprotein core, act as viscoelastic fluids rather than solids, and are largely invariant to humidity. Here, we use spectroscopic and staining methods to show that the gumfoot silk produced by Latrodectus hesperus (western black widow) is composed of hygroscopic organic salts and water insoluble glycoproteins, similar to viscid silk, in addition to a low concentration of spider coating peptides reported before. Our adhesion studies reveal that the organic salts play an important role in adhesion, similar to that seen in orb web spiders, but modulating function at much lower humidity. Our work shows more similarities in the viscid silk produced by orb web and cobweb spiders than previously anticipated and provide guidelines for developing synthetic adhesives that can work in dry to humid environments.

  2. Composition and Function of Spider Glues Maintained During the Evolution of Cobwebs.

    PubMed

    Jain, Dharamdeep; Zhang, Ci; Cool, Lydia Rose; Blackledge, Todd A; Wesdemiotis, Chrys; Miyoshi, Toshikazu; Dhinojwala, Ali

    2015-10-12

    Capture silks are an interesting class of biological glues that help spiders subdue their prey. Viscid capture silk produced by the orb web spiders is a combination of hygroscopic salts that aid in water uptake and interact with adhesive glycoproteins to make them soft and sticky. The orb was a stepping stone to the evolution of new web types, but little is known about the adhesives in these webs. For instance, cobweb spiders evolved from orb-weaving ancestors and utilize glue in specialized sticky gumfoot threads rather than an elastic spiral. Early investigation suggests that gumfoot adhesives are quite different viscid glues because they lack a visible glycoprotein core, act as viscoelastic fluids rather than solids, and are largely invariant to humidity. Here, we use spectroscopic and staining methods to show that the gumfoot silk produced by Latrodectus hesperus (western black widow) is composed of hygroscopic organic salts and water insoluble glycoproteins, similar to viscid silk, in addition to a low concentration of spider coating peptides reported before. Our adhesion studies reveal that the organic salts play an important role in adhesion, similar to that seen in orb web spiders, but modulating function at much lower humidity. Our work shows more similarities in the viscid silk produced by orb web and cobweb spiders than previously anticipated and provide guidelines for developing synthetic adhesives that can work in dry to humid environments. PMID:26322742

  3. Redescriptions of poorly known species of jumping spiders (Araneae: Salticidae) from South Africa and Namibia.

    PubMed

    Azarkina, Galina N; Foord, Stefan H

    2013-01-01

    The following seven species of southern African Salticidae, known only from type specimens or one sex, and last described in the early 20th century, are redescribed: Baryphas ahenus Simon, 1902, Brancus muticus Simon, 1902, Euophrys quadrispinosa Lawrence, 1927, Evarcha natalica Simon, 1902, Mogrus macrocephalus Lawrence, 1927, Thyene damarensis Lawrence, 1927 and Thyene bilineata Lawrence, 1927. Two new synonyms are proposed, Thyene damarensis Lawrence, 1927 syn. n. with Hyllus dotatus (Peckham et Peckham, 1903) and Thyene bilineata striatipes Lawrence, 1927 syn. n. with T bilineata Lawrence, 1927. One new combination is proposed, Thyenula natalica comb. n. (ex Evarcha). Leetotypes for Baryphas ahenus Simon, 1902 and Thyene bilineata Lawrence, 1927 are designated. The female of Brancus muticus Simon, 1902 is described for the first time. PMID:26473213

  4. Coy Males and Seductive Females in the Sexually Cannibalistic Colonial Spider, Cyrtophora citricola.

    PubMed

    Yip, Eric C; Berner-Aharon, Na'ama; Smith, Deborah R; Lubin, Yael

    2016-01-01

    The abundance of sperm relative to eggs selects for males that maximize their number of mates and for females that choose high quality males. However, in many species, males exercise mate choice, even when they invest little in their offspring. Sexual cannibalism may promote male choosiness by limiting the number of females a male can inseminate and by biasing the sex ratio toward females because, while females can reenter the mating pool, cannibalized males cannot. These effects may be insufficient for male choosiness to evolve, however, if males face low sequential encounter rates with females. We hypothesized that sexual cannibalism should facilitate the evolution of male choosiness in group living species because a male is likely to encounter multiple receptive females simultaneously. We tested this hypothesis in a colonial orb-weaving spider, Cyrtophora citricola, with a high rate of sexual cannibalism. We tested whether mated females would mate with multiple males, and thereby shift the operational sex ratio toward females. We also investigated whether either sex chooses mates based on nutritional state and age, and whether males choose females based on reproductive state. We found that females are readily polyandrous and exhibit no mate choice related to male feeding or age. Males courted more often when the male was older and the female was younger, and males copulated more often with well-fed females. The data show that males are choosier than females for the traits we measured, supporting our hypothesis that group living and sexual cannibalism may together promote the evolution of male mate choice. PMID:27249787

  5. Coy Males and Seductive Females in the Sexually Cannibalistic Colonial Spider, Cyrtophora citricola

    PubMed Central

    Yip, Eric C.; Berner-Aharon, Na’ama; Smith, Deborah R.; Lubin, Yael

    2016-01-01

    The abundance of sperm relative to eggs selects for males that maximize their number of mates and for females that choose high quality males. However, in many species, males exercise mate choice, even when they invest little in their offspring. Sexual cannibalism may promote male choosiness by limiting the number of females a male can inseminate and by biasing the sex ratio toward females because, while females can reenter the mating pool, cannibalized males cannot. These effects may be insufficient for male choosiness to evolve, however, if males face low sequential encounter rates with females. We hypothesized that sexual cannibalism should facilitate the evolution of male choosiness in group living species because a male is likely to encounter multiple receptive females simultaneously. We tested this hypothesis in a colonial orb-weaving spider, Cyrtophora citricola, with a high rate of sexual cannibalism. We tested whether mated females would mate with multiple males, and thereby shift the operational sex ratio toward females. We also investigated whether either sex chooses mates based on nutritional state and age, and whether males choose females based on reproductive state. We found that females are readily polyandrous and exhibit no mate choice related to male feeding or age. Males courted more often when the male was older and the female was younger, and males copulated more often with well-fed females. The data show that males are choosier than females for the traits we measured, supporting our hypothesis that group living and sexual cannibalism may together promote the evolution of male mate choice. PMID:27249787

  6. Descriptions of four kleptoparasitic spiders of the genus Mysmenopsis (Araneae, Mysmenidae) and their potential host spider species in the genus Linothele (Araneae, Dipluridae) from Ecuador.

    PubMed

    Dupérré, Nadine; Tapia, Elicio

    2015-06-12

    Four new species of the genus Mysmenopsis are described: M. onorei n. sp., M. otonga n. sp., M. fernandoi n. sp. and M. chiquita n. sp. All species were collected in diplurid webs and are therefore assumed to be kleptoparasitic. Five potential host species of the genus Linothele (Dipluridae) that were collected with the symbionts are also described: Linothele yanachanka n. sp., L. pukachumpi n. sp., L. zaia n. sp., L. tsachilas n. sp. and L. quori n. sp.

  7. From repulsion to attraction: species- and spatial context-dependent threat sensitive response of the spider mite Tetranychus urticae to predatory mite cues

    NASA Astrophysics Data System (ADS)

    Fernández Ferrari, M. Celeste; Schausberger, Peter

    2013-06-01

    Prey perceiving predation risk commonly change their behavior to avoid predation. However, antipredator strategies are costly. Therefore, according to the threat-sensitive predator avoidance hypothesis, prey should match the intensity of their antipredator behaviors to the degree of threat, which may depend on the predator species and the spatial context. We assessed threat sensitivity of the two-spotted spider mite, Tetranychus urticae, to the cues of three predatory mites, Phytoseiulus persimilis, Neoseiulus californicus, and Amblyseius andersoni, posing different degrees of risk in two spatial contexts. We first conducted a no-choice test measuring oviposition and activity of T. urticae exposed to chemical traces of predators or traces plus predator eggs. Then, we tested the site preference of T. urticae in choice tests, using artificial cages and leaves. In the no-choice test, T. urticae deposited their first egg later in the presence of cues of P. persimilis than of the other two predators and cue absence, indicating interspecific threat-sensitivity. T. urticae laid also fewer eggs in the presence of cues of P. persimilis and A. andersoni than of N. californicus and cue absence. In the artificial cage test, the spider mites preferred the site with predator traces, whereas in the leaf test, they preferentially resided on leaves without traces. We argue that in a nonplant environment, chemical predator traces do not indicate a risk for T. urticae, and instead, these traces function as indirect habitat cues. The spider mites were attracted to these cues because they associated them with the existence of a nearby host plant.

  8. From repulsion to attraction: species- and spatial context-dependent threat sensitive response of the spider mite Tetranychus urticae to predatory mite cues.

    PubMed

    Fernández Ferrari, M Celeste; Schausberger, Peter

    2013-06-01

    Prey perceiving predation risk commonly change their behavior to avoid predation. However, antipredator strategies are costly. Therefore, according to the threat-sensitive predator avoidance hypothesis, prey should match the intensity of their antipredator behaviors to the degree of threat, which may depend on the predator species and the spatial context. We assessed threat sensitivity of the two-spotted spider mite, Tetranychus urticae, to the cues of three predatory mites, Phytoseiulus persimilis, Neoseiulus californicus, and Amblyseius andersoni, posing different degrees of risk in two spatial contexts. We first conducted a no-choice test measuring oviposition and activity of T. urticae exposed to chemical traces of predators or traces plus predator eggs. Then, we tested the site preference of T. urticae in choice tests, using artificial cages and leaves. In the no-choice test, T. urticae deposited their first egg later in the presence of cues of P. persimilis than of the other two predators and cue absence, indicating interspecific threat-sensitivity. T. urticae laid also fewer eggs in the presence of cues of P. persimilis and A. andersoni than of N. californicus and cue absence. In the artificial cage test, the spider mites preferred the site with predator traces, whereas in the leaf test, they preferentially resided on leaves without traces. We argue that in a nonplant environment, chemical predator traces do not indicate a risk for T. urticae, and instead, these traces function as indirect habitat cues. The spider mites were attracted to these cues because they associated them with the existence of a nearby host plant.

  9. Taxonomic revision of the Neotropical pirate spiders of the genus Gelanor Thorell, 1869 (Araneae, Mimetidae) with the description of five new species.

    PubMed

    Benavides, Ligia R; Hormiga, Gustavo

    2016-01-01

    We revise the Neotropical spider genus Gelanor Thorell, 1869 (Mimetidae). Gelanor is distributed from northeast Mexico to southern Uruguay , from sea level to 1,600 m. We describe five new species of Gelanor and report eleven new synonymies. Gelanor is here circumscribed to include ten species: Gelanor fortuna new species, Gelanor juruti new species, Gelanor moyobamba new species, Gelanor siquirres new species, Gelanor waorani new species, Gelanor altithorax Keyserling, 1893 (= Gelanor lanei Soares, 1941 new synonymy), Gelanor consequus O. P.-Cambridge, 1902 (= Gelanor depressus Chickering, 1956 new synonymy, Gelanor gertschi Chickering, 1947 new synonymy and Gelanor heraldicus Petrunkevitch, 1925 new synonymy), Gelanor innominatus Chamberlin, 1916, Gelanor latus (Keyserling, 1881) (= Gelanor mixtus O. P.-Cambridge, 1899 new synonymy, Gelanor mabelae Chickering, 1947 new synonymy, Gelanor ornatus Schenkel, 1953 new synonymy and Gelanor proximus Mello-Leitão, 1929 new synonymy) and Gelanor zonatus (C.L. Koch, 1845) (= Gelanor distinctus O-P. Cambridge, 1899 new synonymy, Gelanor insularis Mello-Leitão, 1929 new synonymy and Gelanor obscurus Mello-Leitão, 1929 new synonymy). In addition, we describe for the first time the males of G. altithorax and G. consequus. Species descriptions are provided for all ten species in the genus, together with a compilation of available data, including type specimens, type localities and morphological diagnoses. Light and electron microscope images and updated data on known geographical distributions, are also provided. We also discuss the phylogenetic placement of Gelanor in Mimetidae. PMID:27395525

  10. Spider Bites (For Parents)

    MedlinePlus

    ... Things to Know About Zika & Pregnancy First Aid: Spider Bites KidsHealth > For Parents > First Aid: Spider Bites ... rare. Signs and Symptoms Of a brown recluse spider bite: red blister in the center with surrounding ...

  11. Optimal foraging, not biogenetic law, predicts spider orb web allometry.

    PubMed

    Gregorič, Matjaž; Kiesbüy, Heine C; Lebrón, Shakira G Quiñones; Rozman, Alenka; Agnarsson, Ingi; Kuntner, Matjaž

    2013-03-01

    The biogenetic law posits that the ontogeny of an organism recapitulates the pattern of evolutionary changes. Morphological evidence has offered some support for, but also considerable evidence against, the hypothesis. However, biogenetic law in behavior remains underexplored. As physical manifestation of behavior, spider webs offer an interesting model for the study of ontogenetic behavioral changes. In orb-weaving spiders, web symmetry often gets distorted through ontogeny, and these changes have been interpreted to reflect the biogenetic law. Here, we test the biogenetic law hypothesis against the alternative, the optimal foraging hypothesis, by studying the allometry in Leucauge venusta orb webs. These webs range in inclination from vertical through tilted to horizontal; biogenetic law predicts that allometry relates to ontogenetic stage, whereas optimal foraging predicts that allometry relates to gravity. Specifically, pronounced asymmetry should only be seen in vertical webs under optimal foraging theory. We show that, through ontogeny, vertical webs in L. venusta become more asymmetrical in contrast to tilted and horizontal webs. Biogenetic law thus cannot explain L. venusta web allometry, but our results instead support optimization of foraging area in response to spider size.

  12. Changes in the Adhesive Properties of Spider Aggregate Glue During the Evolution of Cobwebs

    PubMed Central

    Sahni, Vasav; Blackledge, Todd A.; Dhinojwala, Ali

    2011-01-01

    We compare the prey capture glues produced by orb-weaving spiders (viscid glue) and their evolutionary descendents, the cobweb-weaving spiders (gumfoot glue). These glues are produced in homologous glands but exhibit contrasting structure, properties and response to changing humidity. Individual glue droplet stretching measurements indicate that the gumfoot glue behaves like a viscoelastic liquid in contrast to the viscid glue, which behaves like a viscoelastic solid. Moreover, the gumfoot glue is largely humidity-resistant – elasticity and adhesion are constant across variation in humidity and there is weak volume-dependence. Viscid glue, however, is highly humidity-sensitive. The glue expands an order of magnitude and demonstrates a monotonous reduction in elasticity under increased humidity, while glue adhesion optimizes at intermediate levels of humidity. We suggest that observed differences are due to different ‘tackifiers' used in these systems. These results shall inspire future efforts in fabricating stimuli-resistant and stimuli-sensitive materials. PMID:22355560

  13. Ancient Properties of Spider Silks Revealed by the Complete Gene Sequence of the Prey-Wrapping Silk Protein (AcSp1)

    PubMed Central

    Ayoub, Nadia A.; Garb, Jessica E.; Kuelbs, Amanda; Hayashi, Cheryl Y.

    2013-01-01

    Spider silk fibers have impressive mechanical properties and are primarily composed of highly repetitive structural proteins (termed spidroins) encoded by a single gene family. Most characterized spidroin genes are incompletely known because of their extreme size (typically >9 kb) and repetitiveness, limiting understanding of the evolutionary processes that gave rise to their unusual gene architectures. The only complete spidroin genes characterized thus far form the dragline in the Western black widow, Latrodectus hesperus. Here, we describe the first complete gene sequence encoding the aciniform spidroin AcSp1, the primary component of spider prey-wrapping fibers. L. hesperus AcSp1 contains a single enormous (∼19 kb) exon. The AcSp1 repeat sequence is exceptionally conserved between two widow species (∼94% identity) and between widows and distantly related orb-weavers (∼30% identity), consistent with a history of strong purifying selection on its amino acid sequence. Furthermore, the 16 repeats (each 371–375 amino acids long) found in black widow AcSp1 are, on average, >99% identical at the nucleotide level. A combination of stabilizing selection on amino acid sequence, selection on silent sites, and intragenic recombination likely explains the extreme homogenization of AcSp1 repeats. In addition, phylogenetic analyses of spidroin paralogs support a gene duplication event occurring concomitantly with specialization of the aciniform glands and the tubuliform glands, which synthesize egg-case silk. With repeats that are dramatically different in length and amino acid composition from dragline spidroins, our L. hesperus AcSp1 expands the knowledge base for developing silk-based biomimetic technologies. PMID:23155003

  14. Arboreal spiders in eastern hemlock.

    PubMed

    Mallis, Rachael E; Rieske, Lynne K

    2011-12-01

    Eastern hemlock [Tsuga canadensis (L.) Carrière] is a foundation species in forests of eastern North America that plays a key role in ecosystem function. It is highly susceptible to the exotic invasive hemlock woolly adelgid (Adelges tsugae Annand), which is causing widespread hemlock mortality. We surveyed the spider communities of eastern hemlock and deciduous canopies over 2 yr, collecting over 4,000 spiders from 21 families. We found that eastern hemlock canopies harbored a more abundant, rich, and diverse spider community than did deciduous canopies. Five spider families were present in our hemlock collections that were absent from the deciduous collections, including Mysmenidae, Theridiosomatidae, Mimetidae, Lycosidae, and Agelenidae. In hemlock canopies there were 4× the number of web builders, consisting primarily of the Tetragnathidae and Araneidae, than active hunters, consisting primarily of the Anyphaenidae and the Salticidae. Ours is the first in depth study of the spider community in eastern hemlock. Spider abundance in hemlock canopies suggest that they may play a role regulating herbivore populations, and could possibly affect the invasive hemlock woolly adelgid, either through direct consumption of the adelgids themselves or through interactions with classical biological control agents.

  15. Fish predation by semi-aquatic spiders: a global pattern.

    PubMed

    Nyffeler, Martin; Pusey, Bradley J

    2014-01-01

    More than 80 incidences of fish predation by semi-aquatic spiders--observed at the fringes of shallow freshwater streams, rivers, lakes, ponds, swamps, and fens--are reviewed. We provide evidence that fish predation by semi-aquatic spiders is geographically widespread, occurring on all continents except Antarctica. Fish predation by spiders appears to be more common in warmer areas between 40° S and 40° N. The fish captured by spiders, usually ranging from 2-6 cm in length, are among the most common fish taxa occurring in their respective geographic area (e.g., mosquitofish [Gambusia spp.] in the southeastern USA, fish of the order Characiformes in the Neotropics, killifish [Aphyosemion spp.] in Central and West Africa, as well as Australian native fish of the genera Galaxias, Melanotaenia, and Pseudomugil). Naturally occurring fish predation has been witnessed in more than a dozen spider species from the superfamily Lycosoidea (families Pisauridae, Trechaleidae, and Lycosidae), in two species of the superfamily Ctenoidea (family Ctenidae), and in one species of the superfamily Corinnoidea (family Liocranidae). The majority of reports on fish predation by spiders referred to pisaurid spiders of the genera Dolomedes and Nilus (>75% of observed incidences). There is laboratory evidence that spiders from several more families (e.g., the water spider Argyroneta aquatica [Cybaeidae], the intertidal spider Desis marina [Desidae], and the 'swimming' huntsman spider Heteropoda natans [Sparassidae]) predate fish as well. Our finding of such a large diversity of spider families being engaged in fish predation is novel. Semi-aquatic spiders captured fish whose body length exceeded the spiders' body length (the captured fish being, on average, 2.2 times as long as the spiders). Evidence suggests that fish prey might be an occasional prey item of substantial nutritional importance.

  16. Spider Webs and Silks.

    ERIC Educational Resources Information Center

    Vollrath, Fritz

    1992-01-01

    Compares the attributes of the silk from spiders with those of the commercially harvested silk from silkworms. Discusses the evolution, design, and effectiveness of spider webs; the functional mechanics of the varieties of silk that can be produced by the same spider; and the composite, as well as molecular, structure of spider silk thread. (JJK)

  17. Energetics, scaling and sexual size dimorphism of spiders.

    PubMed

    Grossi, B; Canals, M

    2015-03-01

    The extreme sexual size dimorphism in spiders has motivated studies for many years. In many species the male can be very small relative to the female. There are several hypotheses trying to explain this fact, most of them emphasizing the role of energy in determining spider size. The aim of this paper is to review the role of energy in sexual size dimorphism of spiders, even for those spiders that do not necessarily live in high foliage, using physical and allometric principles. Here we propose that the cost of transport or equivalently energy expenditure and the speed are traits under selection pressure in male spiders, favoring those of smaller size to reduce travel costs. The morphology of the spiders responds to these selective forces depending upon the lifestyle of the spiders. Climbing and bridging spiders must overcome the force of gravity. If bridging allows faster dispersal, small males would have a selective advantage by enjoying more mating opportunities. In wandering spiders with low population density and as a consequence few male-male interactions, high speed and low energy expenditure or cost of transport should be favored by natural selection. Pendulum mechanics show the advantages of long legs in spiders and their relationship with high speed, even in climbing and bridging spiders. Thus small size, compensated by long legs should be the expected morphology for a fast and mobile male spider.

  18. Changes in species diversity of arboreal spiders in Mexican coffee agroecosystems: untangling the web of local and landscape influences driving diversity.

    PubMed

    Hajian-Forooshani, Zachary; Gonthier, David J; Marín, Linda; Iverson, Aaron L; Perfecto, Ivette

    2014-01-01

    Agricultural intensification is implicated as a major driver of global biodiversity loss. Local management and landscape scale factors both influence biodiversity in agricultural systems, but there are relatively few studies to date looking at how local and landscape scales influence biodiversity in tropical agroecosystems. Understanding what drives the diversity of groups of organisms such as spiders is important from a pragmatic point of view because of the important biocontrol services they offer to agriculture. Spiders in coffee are somewhat enigmatic because of their positive or lack of response to agricultural intensification. In this study, we provide the first analysis, to our knowledge, of the arboreal spiders in the shade trees of coffee plantations. In the Soconusco region of Chiapas, Mexico we sampled across 38 sites on 9 coffee plantations. Tree and canopy connectedness were found to positively influence overall arboreal spider richness and abundance. We found that different functional groups of spiders are responding to different local and landscape factors, but overall elevation was most important variable influencing arboreal spider diversity. Our study has practical management applications that suggest having shade grown coffee offers more suitable habitat for arboreal spiders due to a variety of the characteristics of the shade trees. Our results which show consistently more diverse arboreal spider communities in lower elevations are important in light of looming global climate change. As the range of suitable elevations for coffee cultivation shrinks promoting arboreal spider diversity will be important in sustaining the viability of coffee. PMID:25392751

  19. Changes in species diversity of arboreal spiders in Mexican coffee agroecosystems: untangling the web of local and landscape influences driving diversity.

    PubMed

    Hajian-Forooshani, Zachary; Gonthier, David J; Marín, Linda; Iverson, Aaron L; Perfecto, Ivette

    2014-01-01

    Agricultural intensification is implicated as a major driver of global biodiversity loss. Local management and landscape scale factors both influence biodiversity in agricultural systems, but there are relatively few studies to date looking at how local and landscape scales influence biodiversity in tropical agroecosystems. Understanding what drives the diversity of groups of organisms such as spiders is important from a pragmatic point of view because of the important biocontrol services they offer to agriculture. Spiders in coffee are somewhat enigmatic because of their positive or lack of response to agricultural intensification. In this study, we provide the first analysis, to our knowledge, of the arboreal spiders in the shade trees of coffee plantations. In the Soconusco region of Chiapas, Mexico we sampled across 38 sites on 9 coffee plantations. Tree and canopy connectedness were found to positively influence overall arboreal spider richness and abundance. We found that different functional groups of spiders are responding to different local and landscape factors, but overall elevation was most important variable influencing arboreal spider diversity. Our study has practical management applications that suggest having shade grown coffee offers more suitable habitat for arboreal spiders due to a variety of the characteristics of the shade trees. Our results which show consistently more diverse arboreal spider communities in lower elevations are important in light of looming global climate change. As the range of suitable elevations for coffee cultivation shrinks promoting arboreal spider diversity will be important in sustaining the viability of coffee.

  20. Disentangling the phylogenetic and ecological components of spider phenotypic variation.

    PubMed

    Gonçalves-Souza, Thiago; Diniz-Filho, José Alexandre Felizola; Romero, Gustavo Quevedo

    2014-01-01

    An understanding of how the degree of phylogenetic relatedness influences the ecological similarity among species is crucial to inferring the mechanisms governing the assembly of communities. We evaluated the relative importance of spider phylogenetic relationships and ecological niche (plant morphological variables) to the variation in spider body size and shape by comparing spiders at different scales: (i) between bromeliads and dicot plants (i.e., habitat scale) and (ii) among bromeliads with distinct architectural features (i.e., microhabitat scale). We partitioned the interspecific variation in body size and shape into phylogenetic (that express trait values as expected by phylogenetic relationships among species) and ecological components (that express trait values independent of phylogenetic relationships). At the habitat scale, bromeliad spiders were larger and flatter than spiders associated with the surrounding dicots. At this scale, plant morphology sorted out close related spiders. Our results showed that spider flatness is phylogenetically clustered at the habitat scale, whereas it is phylogenetically overdispersed at the microhabitat scale, although phylogenic signal is present in both scales. Taken together, these results suggest that whereas at the habitat scale selective colonization affect spider body size and shape, at fine scales both selective colonization and adaptive evolution determine spider body shape. By partitioning the phylogenetic and ecological components of phenotypic variation, we were able to disentangle the evolutionary history of distinct spider traits and show that plant architecture plays a role in the evolution of spider body size and shape. We also discussed the relevance in considering multiple scales when studying phylogenetic community structure.

  1. Proteome and peptidome profiling of spider venoms.

    PubMed

    Liang, Songping

    2008-10-01

    Spider venoms are an important source of novel molecules with different pharmacological properties. Recent technological developments of proteomics, especially mass spectrometry, have greatly promoted the systematic analysis of spider venom. The enormous diversity of venom components between spider species and the lack of complete genome sequence, and the limited database of protein and peptide sequences make spider venom profiling a challenging task and special considerations for technical strategies are required. This review highlights recently used methods for spider venom profiling. In general, spider venom profiling can be achieved in two parts: proteome profiling of the components with molecular weights above 10 kDa, and peptidome profiling of the components with a molecular weight of 10 kDa or under through the use of different methods. Venom proteomes are rich in various enzymes, hemocyanins, toxin-like proteins and many unknown proteins. Peptidomes are dominated by peptides with a mass of 3-6 kDa with three to five disulfide bonds. Although there are some similarities in peptide superfamily types of venoms from different spider species, the venom profile of each species is unique. The linkage of the peptidomic data with that of the cDNA approach is discussed briefly. Future challenges and perspectives are also highlighted in this review.

  2. Fish Predation by Semi-Aquatic Spiders: A Global Pattern

    PubMed Central

    Nyffeler, Martin; Pusey, Bradley J.

    2014-01-01

    More than 80 incidences of fish predation by semi-aquatic spiders – observed at the fringes of shallow freshwater streams, rivers, lakes, ponds, swamps, and fens – are reviewed. We provide evidence that fish predation by semi-aquatic spiders is geographically widespread, occurring on all continents except Antarctica. Fish predation by spiders appears to be more common in warmer areas between 40° S and 40° N. The fish captured by spiders, usually ranging from 2–6 cm in length, are among the most common fish taxa occurring in their respective geographic area (e.g., mosquitofish [Gambusia spp.] in the southeastern USA, fish of the order Characiformes in the Neotropics, killifish [Aphyosemion spp.] in Central and West Africa, as well as Australian native fish of the genera Galaxias, Melanotaenia, and Pseudomugil). Naturally occurring fish predation has been witnessed in more than a dozen spider species from the superfamily Lycosoidea (families Pisauridae, Trechaleidae, and Lycosidae), in two species of the superfamily Ctenoidea (family Ctenidae), and in one species of the superfamily Corinnoidea (family Liocranidae). The majority of reports on fish predation by spiders referred to pisaurid spiders of the genera Dolomedes and Nilus (>75% of observed incidences). There is laboratory evidence that spiders from several more families (e.g., the water spider Argyroneta aquatica [Cybaeidae], the intertidal spider Desis marina [Desidae], and the ‘swimming’ huntsman spider Heteropoda natans [Sparassidae]) predate fish as well. Our finding of such a large diversity of spider families being engaged in fish predation is novel. Semi-aquatic spiders captured fish whose body length exceeded the spiders’ body length (the captured fish being, on average, 2.2 times as long as the spiders). Evidence suggests that fish prey might be an occasional prey item of substantial nutritional importance. PMID:24940885

  3. Spider silk reduces insect herbivory.

    PubMed

    Rypstra, Ann L; Buddle, Christopher M

    2013-02-23

    The role of predators in food webs extends beyond their ability to kill and consume prey. Such trait-mediated effects occur when signals of the predator influence the behaviour of other animals. Because all spiders are silk-producing carnivores, we hypothesized that silk alone would signal other arthropods and enhance non-lethal effects of spiders. We quantified the herbivory inflicted by two beetle species on green bean plants (Phaseolus vulgaris) in the presence of silkworm silk and spider silk along with no silk controls. Single leaflets were treated and enclosed with herbivores in the laboratory and field. Another set of leaflets were treated and left to experience natural herbivory in the field. Entire plants in the field were treated with silk and enclosed with herbivores or left exposed to herbivory. In all cases, the lowest levels of herbivory occurred with spider silk treatments and, in general, silkworm silk produced intermediate levels of leaf damage. These results suggest that silk may be a mechanism for the trait-mediated impacts of spiders and that it might contribute to integrated pest management programmes.

  4. Astacin-like metalloproteases are a gene family of toxins present in the venom of different species of the brown spider (genus Loxosceles).

    PubMed

    Trevisan-Silva, Dilza; Gremski, Luiza H; Chaim, Olga M; da Silveira, Rafael B; Meissner, Gabriel O; Mangili, Oldemir C; Barbaro, Katia C; Gremski, Waldemiro; Veiga, Silvio S; Senff-Ribeiro, Andrea

    2010-01-01

    Brown spiders have a worldwide distribution, and their venom has a complex composition containing many different molecules. Herein, we report the existence of a family of astacin-like metalloprotease toxins in Loxosceles intermedia venom, as well as in the venom of different species of Loxosceles. Using a cDNA library from the L. intermedia venom gland, we cloned two novel cDNAs encoding astacin-like metalloprotease toxins, LALP2 and LALP3. Using an anti-serum against the previously described astacin-like toxin in L. intermedia venom (LALP1), we detected the presence of immunologically-related toxins in the venoms of L. intermedia, Loxosceles laeta, and Loxosceles gaucho. Zymographic experiments showed gelatinolytic activity of crude venoms of L. intermedia, L. laeta, and L. gaucho (which could be inhibited by the divalent metal chelator 1,10-phenanthroline) at electrophoretic mobilities identical to those reported for immunological cross-reactivity. Moreover, mRNAs extracted from L. laeta and L. gaucho venom glands were screened for astacin-like metalloproteases, and cDNAs obtained using LALP1-specific primers were sequenced, and their deduced amino acid sequences confirmed they were members of the astacin family with the family signatures (HEXXHXXGXXHE and MXY), LALP4 and LALP5, respectively. Sequence comparison of deduced amino acid sequences revealed that LALP2, LALP3, LALP4, and LALP5 are related to the astacin family. This study identified the existence of gene family of astacin-like toxins in the venoms of brown spiders and raises the possibility that these molecules are involved in the deleterious effects triggered by the venom.

  5. The execution of planned detours by spider-eating predators.

    PubMed

    Cross, Fiona R; Jackson, Robert R

    2016-01-01

    Many spiders from the salticid subfamily Spartaeinae specialize at preying on other spiders and they adopt complex strategies when targeting these dangerous prey. We tested 15 of these spider-eating spartaeine species for the capacity to plan detours ahead of time. Each trial began with the test subject on top of a tower from which it could view two boxes: one containing prey and the other not containing prey. The distance between the tower and the boxes was too far to reach by leaping and the tower sat on a platform surrounded by water. As the species studied are known to avoid water, the only way they could reach the prey without getting wet was by taking one of two circuitous walkways from the platform: one leading to the prey ('correct') and one not leading to the prey ('incorrect'). After leaving the tower, the test subject could not see the prey and sometimes it had to walk past the incorrect walkway before reaching the correct walkway. Yet all 15 species chose the correct walkway significantly more often than the incorrect walkway. We propose that these findings exemplify genuine cognition based on representation. PMID:26781057

  6. Tangled in a sparse spider web: single origin of orb weavers and their spinning work unravelled by denser taxonomic sampling.

    PubMed

    Dimitrov, Dimitar; Lopardo, Lara; Giribet, Gonzalo; Arnedo, Miquel A; Alvarez-Padilla, Fernando; Hormiga, Gustavo

    2012-04-01

    In order to study the tempo and the mode of spider orb web evolution and diversification, we conducted a phylogenetic analysis using six genetic markers along with a comprehensive taxon sample. The present analyses are the first to recover the monophyly of orb-weaving spiders based solely on DNA sequence data and an extensive taxon sample. We present the first dated orb weaver phylogeny. Our results suggest that orb weavers appeared by the Middle Triassic and underwent a rapid diversification during the end of the Triassic and Early Jurassic. By the second half of the Jurassic, most of the extant orb-weaving families and web designs were already present. The processes that may have given origin to this diversification of lineages and web architectures are discussed. A combination of biotic factors, such as key innovations in web design and silk composition, as well as abiotic environmental changes, may have played important roles in the diversification of orb weavers. Our analyses also show that increased taxon sampling density in both ingroups and outgroups greatly improves phylogenetic accuracy even when extensive data are missing. This effect is particularly important when addition of character data improves gene overlap. PMID:22048955

  7. Tangled in a sparse spider web: single origin of orb weavers and their spinning work unravelled by denser taxonomic sampling.

    PubMed

    Dimitrov, Dimitar; Lopardo, Lara; Giribet, Gonzalo; Arnedo, Miquel A; Alvarez-Padilla, Fernando; Hormiga, Gustavo

    2012-04-01

    In order to study the tempo and the mode of spider orb web evolution and diversification, we conducted a phylogenetic analysis using six genetic markers along with a comprehensive taxon sample. The present analyses are the first to recover the monophyly of orb-weaving spiders based solely on DNA sequence data and an extensive taxon sample. We present the first dated orb weaver phylogeny. Our results suggest that orb weavers appeared by the Middle Triassic and underwent a rapid diversification during the end of the Triassic and Early Jurassic. By the second half of the Jurassic, most of the extant orb-weaving families and web designs were already present. The processes that may have given origin to this diversification of lineages and web architectures are discussed. A combination of biotic factors, such as key innovations in web design and silk composition, as well as abiotic environmental changes, may have played important roles in the diversification of orb weavers. Our analyses also show that increased taxon sampling density in both ingroups and outgroups greatly improves phylogenetic accuracy even when extensive data are missing. This effect is particularly important when addition of character data improves gene overlap.

  8. Structure-activity relationship study of spider polyamine toxins as inhibitors of ionotropic glutamate receptors.

    PubMed

    Xiong, Xiao-Feng; Poulsen, Mette H; Hussein, Rama A; Nørager, Niels G; Strømgaard, Kristian

    2014-12-01

    The spider polyamine toxins Joro spider toxin-3 (JSTX-3) and Nephila polyamine toxins-1 and -8 (NPTX-1 and NPTX-8) are isolated from the venom of the orb-weaver spider Nephila clavata (Joro spider). They share a high degree of structural resemblance, their aromatic head groups being the only difference, and were recently found to be very potent open-channel blockers of ionotropic glutamate (iGlu) receptors. In this study we designed and synthesized a collection of 24 analogues of these toxins using a recently developed solid-phase synthetic methodology. Systematic variation in two regions of the toxins and subsequent evaluation of biological activity at AMPA and NMDA subtypes of iGlu receptors provided succinct information on structure-activity relationships. In particular, one set of analogues were found to display exquisite selectivity and potency for AMPA receptors relative to the natural products. Thus, this systematic SAR study has provided new pharmacological tools for studies of iGlu receptors.

  9. Samadinia longispina, a new genus and species of deep-sea spider crab from the western Pacific, and a new species of Rochinia A. Milne-Edwards, 1875, from Papua New Guinea (Crustacea: Brachyura: Majoidea: Epialtidae).

    PubMed

    Ng, Peter K L; Richer De Forges, Bertrand

    2013-01-01

    A new genus, Samadinia n. gen., and new species, Samadinia longispina n. sp., of deep-water epialtid spider crab is described from French Polynesia and New Caledonia. The new genus is superficially similar to Rochinia A. Milne-Edwards, 1875, but can be distinguished by having the dorsal surface of the carapace covered with small, rounded granules (versus with long spines or strong tubercles), well developed hepatic and lateral branchial spines (versus relatively shorter and weaker), a prominently constricted male thoracic sternite 4 (versus relatively broader with less prominent or without median constriction) and a proportionally broader male abdomen. A new species of Rochinia, R. granulosa n. sp., is also described from Papua New Guinea. It is easily distinguished from congeners its small adult size, the presence of numerous relatively large granules on the carapace and a relatively short hepatic spine.

  10. A Silurian sea spider.

    PubMed

    Siveter, Derek J; Sutton, Mark D; Briggs, Derek E G; Siveter, David J

    2004-10-21

    Pycnogonids (sea spiders) are marine arthropods numbering some 1,160 extant species. They are globally distributed in depths of up to 6,000 metres, and locally abundant; however, their typically delicate form and non-biomineralized cuticle has resulted in an extremely sparse fossil record that is not accepted universally. There are two opposing views of their phylogenetic position: either within Chelicerata as sister group to the euchelicerates, or as a sister taxon to all other euarthropods. The Silurian Herefordshire Konservat-Lagerstatte in England (approximately 425 million years (Myr) bp) yields exceptionally preserved three-dimensional fossils that provide unrivalled insights into the palaeobiology of a variety of invertebrates. The fossils are preserved as calcitic void in-fills in carbonate concretions within a volcaniclastic horizon, and are reconstructed digitally. Here we describe a new pycnogonid from this deposit, which is the oldest adult sea spider by approximately 35 Myr and the most completely known fossil species. The large chelate first appendage is consistent with a chelicerate affinity for the pycnogonids. Cladistic analyses place the new species near the base of the pycnogonid crown group, implying that the latter had arisen by the Silurian period.

  11. Ant mimicry lessens predation on a North American jumping spider by larger salticid spiders.

    PubMed

    Durkee, Caitlin A; Weiss, Martha R; Uma, Divya B

    2011-10-01

    Ant-like appearance (myrmecomorphy) has evolved >70 times in insects and spiders, accounting for >2,000 species of myrmecomorphic arthropods. Most myrmecomorphic spiders are considered to be Batesian mimics; that is, a palatable spider avoids predation through resemblance to an unpalatable ant-although this presumption has been tested in relatively few cases. Here we explicitly examined the extent to which Peckhamia picata (Salticidae), a North American ant-mimicking jumping spider, is protected from four species of jumping spider predators, relative to nonmimetic salticids and model ants. In addition, we conducted focused behavioral observations on one salticid predator, Thiodina puerpera, to determine the point at which the predators' behaviors toward model, mimic, and nonmimic diverge. We also examined the behaviors of Peckhamia in the presence of Thiodina. We found that mimetic jumping spiders were consumed less than a third as often as nonmimetic jumping spiders, suggesting that Peckhamia does indeed gain protection as a result of its resemblance to ants, and so can be considered a Batesian mimic. Furthermore, our focal predator did not consume any ant-mimicking spiders, and seemed to categorize Peckhamia with its model ant early in the hunting sequence. Such early determination of prey versus nonprey may be the result of speed-accuracy trade-offs in predator decision-making.

  12. Ant mimicry lessens predation on a North American jumping spider by larger salticid spiders.

    PubMed

    Durkee, Caitlin A; Weiss, Martha R; Uma, Divya B

    2011-10-01

    Ant-like appearance (myrmecomorphy) has evolved >70 times in insects and spiders, accounting for >2,000 species of myrmecomorphic arthropods. Most myrmecomorphic spiders are considered to be Batesian mimics; that is, a palatable spider avoids predation through resemblance to an unpalatable ant-although this presumption has been tested in relatively few cases. Here we explicitly examined the extent to which Peckhamia picata (Salticidae), a North American ant-mimicking jumping spider, is protected from four species of jumping spider predators, relative to nonmimetic salticids and model ants. In addition, we conducted focused behavioral observations on one salticid predator, Thiodina puerpera, to determine the point at which the predators' behaviors toward model, mimic, and nonmimic diverge. We also examined the behaviors of Peckhamia in the presence of Thiodina. We found that mimetic jumping spiders were consumed less than a third as often as nonmimetic jumping spiders, suggesting that Peckhamia does indeed gain protection as a result of its resemblance to ants, and so can be considered a Batesian mimic. Furthermore, our focal predator did not consume any ant-mimicking spiders, and seemed to categorize Peckhamia with its model ant early in the hunting sequence. Such early determination of prey versus nonprey may be the result of speed-accuracy trade-offs in predator decision-making. PMID:22251733

  13. Ubiquitous distribution of salts and proteins in spider glue enhances spider silk adhesion

    NASA Astrophysics Data System (ADS)

    Amarpuri, Gaurav; Chaurasia, Vishal; Jain, Dharamdeep; Blackledge, Todd A.; Dhinojwala, Ali

    2015-03-01

    Modern orb-weaving spiders use micron-sized glue droplets on their viscid silk to retain prey in webs. A combination of low molecular weight salts and proteins makes the glue viscoelastic and humidity responsive in a way not easily achieved by synthetic adhesives. Optically, the glue droplet shows a heterogeneous structure, but the spatial arrangement of its chemical components is poorly understood. Here, we use optical and confocal Raman microscopy to show that salts and proteins are present ubiquitously throughout the droplet. The distribution of adhesive proteins in the peripheral region explains the superior prey capture performance of orb webs as it enables the entire surface area of the glue droplet to act as a site for prey capture. The presence of salts throughout the droplet explains the recent Solid-State NMR results that show salts directly facilitate protein mobility. Understanding the function of individual glue components and the role of the droplet's macro-structure can help in designing better synthetic adhesives for humid environments.

  14. Ubiquitous distribution of salts and proteins in spider glue enhances spider silk adhesion.

    PubMed

    Amarpuri, Gaurav; Chaurasia, Vishal; Jain, Dharamdeep; Blackledge, Todd A; Dhinojwala, Ali

    2015-01-01

    Modern orb-weaving spiders use micron-sized glue droplets on their viscid silk to retain prey in webs. A combination of low molecular weight salts and proteins makes the glue viscoelastic and humidity responsive in a way not easily achieved by synthetic adhesives. Optically, the glue droplet shows a heterogeneous structure, but the spatial arrangement of its chemical components is poorly understood. Here, we use optical and confocal Raman microscopy to show that salts and proteins are present ubiquitously throughout the droplet. The distribution of adhesive proteins in the peripheral region explains the superior prey capture performance of orb webs as it enables the entire surface area of the glue droplet to act as a site for prey capture. The presence of salts throughout the droplet explains the recent Solid-State NMR results that show salts directly facilitate protein mobility. Understanding the function of individual glue components and the role of the droplet's macro-structure can help in designing better synthetic adhesives for humid environments. PMID:25761668

  15. Brown Recluse Spider

    MedlinePlus

    ... to a group of spiders commonly known as violin spiders or fiddlebacks. The characteristic fiddle-shaped pattern ... 4-19.1mm) • Color: Golden brown • A dark violin/fiddle shape (see top photo) is located on ...

  16. Nature Study Tips. Spiders.

    ERIC Educational Resources Information Center

    Mulaik, Stanley B.

    1990-01-01

    Different types of spiders, their ranges and habits are discussed. Activities associated with the study of spiders are suggested. Four references are listed which may be of interest to beginners. (CW)

  17. Did You Say Spiders?

    ERIC Educational Resources Information Center

    Campbell, Alene

    This spider unit focuses on students' development of cooperative learning and inquiry-based skills. Students read "The Very Busy Spider" by Eric Carle, and then work in cooperative groups using the Internet to research and synthesize important information about spiders. Technology is used for vocabulary instruction and to create a multimedia…

  18. Parapleisticantha Yokoya, 1933, a valid genus of deep-sea inachid spider crab from Japan and the Philippines (Crustacea: Decapoda: Brachyura: Majoidea), with the description of a new species.

    PubMed

    De Forges, Bertrand Richer; Ng, Peter K L; Ahyong, Shane T

    2013-01-01

    The inachid spider crab genus, Parapleisticantha Yokoya, 1933 [type species: Parapleisticantha japonica Yokoya, 1933] is removed from the synonymy of Pleistacantha Miers, 1879 [type species: Pleistacantha sanctijohannis Miers, 1879], and recognised as a valid genus. Parapleisticantha differs from Pleistacantha sensu stricto primarily by having a less spiny carapace, stouter and more inflated male chelipeds, and by lacking a slender subdistal process on the male first gonopod. We redescribe Parapleisticantha japonica based on the Japanese type material and describe as new a second species, Parapleisticantha ludivinae n. sp., recently discovered in the Philippines.

  19. Maternal care and subsocial behaviour in spiders.

    PubMed

    Yip, Eric C; Rayor, Linda S

    2014-05-01

    While most spiders are solitary and opportunistically cannibalistic, a variety of social organisations has evolved in a minority of spider species. One form of social organisation is subsociality, in which siblings remain together with their parent for some period of time but disperse prior to independent reproduction. We review the literature on subsocial and maternal behaviour in spiders to highlight areas in which subsocial spiders have informed our understanding of social evolution and to identify promising areas of future research. We show that subsocial behaviour has evolved independently at least 18 times in spiders, across a wide phylogenetic distribution. Subsocial behaviour is diverse in terms of the form of care provided by the mother, the duration of care and sibling association, the degree of interaction and cooperation among siblings, and the use of vibratory and chemical communication. Subsocial spiders are useful model organisms to study various topics in ecology, such as kin recognition and the evolution of cheating and its impact on societies. Further, why social behaviour evolved in some lineages and not others is currently a topic of debate in behavioural ecology, and we argue that spiders offer an opportunity to untangle the ecological causes of parental care, which forms the basis of many other animal societies.

  20. The eunuch phenomenon: adaptive evolution of genital emasculation in sexually dimorphic spiders.

    PubMed

    Kuntner, Matjaž; Agnarsson, Ingi; Li, Daiqin

    2015-02-01

    Under natural and sexual selection traits often evolve that secure paternity or maternity through self-sacrifice to predators, rivals, offspring, or partners. Emasculation-males removing their genitals-is an unusual example of such behaviours. Known only in insects and spiders, the phenomenon's adaptiveness is difficult to explain, yet its repeated origins and association with sexual size dimorphism (SSD) and sexual cannibalism suggest an adaptive significance. In spiders, emasculation of paired male sperm-transferring organs - secondary genitals - (hereafter, palps), results in 'eunuchs'. This behaviour has been hypothesized to be adaptive because (i) males plug female genitals with their severed palps (plugging hypothesis), (ii) males remove their palps to become better fighters in male-male contests (better-fighter hypothesis), perhaps reaching higher agility due to reduced total body mass (gloves-off hypothesis), and (iii) males achieve prolonged sperm transfer through severed genitals (remote-copulation hypothesis). Prior research has provided evidence in support of these hypotheses in some orb-weaving spiders but these explanations are far from general. Seeking broad macroevolutionary patterns of spider emasculation, we review the known occurrences, weigh the evidence in support of the hypotheses in each known case, and redefine more precisely the particular cases of emasculation depending on its timing in relation to maturation and mating: 'pre-maturation', 'mating', and 'post-mating'. We use a genus-level spider phylogeny to explore emasculation evolution and to investigate potential evolutionary linkage between emasculation, SSD, lesser genital damage (embolic breakage), and sexual cannibalism (females consuming their mates). We find a complex pattern of spider emasculation evolution, all cases confined to Araneoidea: emasculation evolved at least five and up to 11 times, was lost at least four times, and became further modified at least once. We also find

  1. The eunuch phenomenon: adaptive evolution of genital emasculation in sexually dimorphic spiders.

    PubMed

    Kuntner, Matjaž; Agnarsson, Ingi; Li, Daiqin

    2015-02-01

    Under natural and sexual selection traits often evolve that secure paternity or maternity through self-sacrifice to predators, rivals, offspring, or partners. Emasculation-males removing their genitals-is an unusual example of such behaviours. Known only in insects and spiders, the phenomenon's adaptiveness is difficult to explain, yet its repeated origins and association with sexual size dimorphism (SSD) and sexual cannibalism suggest an adaptive significance. In spiders, emasculation of paired male sperm-transferring organs - secondary genitals - (hereafter, palps), results in 'eunuchs'. This behaviour has been hypothesized to be adaptive because (i) males plug female genitals with their severed palps (plugging hypothesis), (ii) males remove their palps to become better fighters in male-male contests (better-fighter hypothesis), perhaps reaching higher agility due to reduced total body mass (gloves-off hypothesis), and (iii) males achieve prolonged sperm transfer through severed genitals (remote-copulation hypothesis). Prior research has provided evidence in support of these hypotheses in some orb-weaving spiders but these explanations are far from general. Seeking broad macroevolutionary patterns of spider emasculation, we review the known occurrences, weigh the evidence in support of the hypotheses in each known case, and redefine more precisely the particular cases of emasculation depending on its timing in relation to maturation and mating: 'pre-maturation', 'mating', and 'post-mating'. We use a genus-level spider phylogeny to explore emasculation evolution and to investigate potential evolutionary linkage between emasculation, SSD, lesser genital damage (embolic breakage), and sexual cannibalism (females consuming their mates). We find a complex pattern of spider emasculation evolution, all cases confined to Araneoidea: emasculation evolved at least five and up to 11 times, was lost at least four times, and became further modified at least once. We also find

  2. Spiders in dermatology.

    PubMed

    Kang, Jun K; Bhate, Chinmoy; Schwartz, Robert A

    2014-09-01

    Spider bites represent an unusual and potentially over-represented clinical diagnosis. Despite a common fear of spiders, known as arachnophobia, current knowledge suggests that only a small number of families within the order Araneae are medically relevant. Moreover, most cutaneous spider reactions, including both evenomations and physical trauma, produce mild, local symptoms which may be managed with supportive care alone. The differential diagnosis for spider bites may be broad, especially if the offending arachnid is not seen or found. We describe a series of spiders relevant to the dermatologist in the United States.

  3. High-performance spider webs: integrating biomechanics, ecology and behaviour.

    PubMed

    Harmer, Aaron M T; Blackledge, Todd A; Madin, Joshua S; Herberstein, Marie E

    2011-04-01

    Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence spider web evolution along different structural pathways, and (ii) how silks function in an ecological context, which may identify novel silk applications. An integrative, mechanistic approach to understanding silk and web function, as well as the selective pressures driving their evolution, will help uncover the potential impacts of environmental change and species invasions (of both spiders and prey) on spider success. Integrating these fields will also allow us to take advantage of the remarkable properties of spider silks, expanding the range of possible silk applications from single threads to two- and three-dimensional thread networks.

  4. High-performance spider webs: integrating biomechanics, ecology and behaviour

    PubMed Central

    Harmer, Aaron M. T.; Blackledge, Todd A.; Madin, Joshua S.; Herberstein, Marie E.

    2011-01-01

    Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence spider web evolution along different structural pathways, and (ii) how silks function in an ecological context, which may identify novel silk applications. An integrative, mechanistic approach to understanding silk and web function, as well as the selective pressures driving their evolution, will help uncover the potential impacts of environmental change and species invasions (of both spiders and prey) on spider success. Integrating these fields will also allow us to take advantage of the remarkable properties of spider silks, expanding the range of possible silk applications from single threads to two- and three-dimensional thread networks. PMID:21036911

  5. Fecundity increase supports adaptive radiation hypothesis in spider web evolution

    PubMed Central

    Coddington, Jonathan A; Agnarsson, Ingi

    2009-01-01

    Identifying the mechanisms driving adaptive radiations is key to explaining the diversity of life. The extreme reliance of spiders upon silk for survival provides an exceptional system in which to link patterns of diversification to adaptive changes in silk use. Most of the world’s 41,000 species of spiders belong to two apical lineages of spiders that exhibit quite different silk ecologies, distinct from their ancestors. Orb spiders spin highly stereotyped webs that are suspended in air and utilize a chemical glue to make them adhesive. RTA clade spiders mostly abandoned silk capture webs altogether. We recently proposed that these two clades present very different evolutionary routes of achieving the same key innovation—escape from the constraints imposed by spinning webs that contain a relatively costly type of physically adhesive cribellate silk. Here, we test the prediction that orb and RTA clade spiders are not only more diverse, but also have higher fecundity than other spiders. We show that RTA clade spiders average 23% higher fecundity and orb spiders average 123% higher fecundity than their ancestors. This supports a functional link between the adaptive escape from cribellate silk and increased resource allocation to reproduction in spiders. PMID:20195450

  6. High-performance spider webs: integrating biomechanics, ecology and behaviour.

    PubMed

    Harmer, Aaron M T; Blackledge, Todd A; Madin, Joshua S; Herberstein, Marie E

    2011-04-01

    Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence spider web evolution along different structural pathways, and (ii) how silks function in an ecological context, which may identify novel silk applications. An integrative, mechanistic approach to understanding silk and web function, as well as the selective pressures driving their evolution, will help uncover the potential impacts of environmental change and species invasions (of both spiders and prey) on spider success. Integrating these fields will also allow us to take advantage of the remarkable properties of spider silks, expanding the range of possible silk applications from single threads to two- and three-dimensional thread networks. PMID:21036911

  7. Fecundity increase supports adaptive radiation hypothesis in spider web evolution.

    PubMed

    Blackledge, Todd A; Coddington, Jonathan A; Agnarsson, Ingi

    2009-11-01

    Identifying the mechanisms driving adaptive radiations is key to explaining the diversity of life. The extreme reliance of spiders upon silk for survival provides an exceptional system in which to link patterns of diversification to adaptive changes in silk use. Most of the world's 41,000 species of spiders belong to two apical lineages of spiders that exhibit quite different silk ecologies, distinct from their ancestors. Orb spiders spin highly stereotyped webs that are suspended in air and utilize a chemical glue to make them adhesive. RTA clade spiders mostly abandoned silk capture webs altogether. We recently proposed that these two clades present very different evolutionary routes of achieving the same key innovation-escape from the constraints imposed by spinning webs that contain a relatively costly type of physically adhesive cribellate silk. Here, we test the prediction that orb and RTA clade spiders are not only more diverse, but also have higher fecundity than other spiders. We show that RTA clade spiders average 23% higher fecundity and orb spiders average 123% higher fecundity than their ancestors. This supports a functional link between the adaptive escape from cribellate silk and increased resource allocation to reproduction in spiders.

  8. A reanalysis of the morphological phylogeny of the spider genus Physocyclus Simon (Araneae: Pholcidae) with the description of a new species and description of the female of Physocyclus paredesi Valdez-Mondragón from Mexico.

    PubMed

    Valdez-Mondragón, Alejandro

    2014-01-01

    A new species of spider from Michoacán, Physocyclus peribanensis sp. nov. is described. This description is based on a male holotype and one female paratype. Also, the first description of the female of Physocyclus paredesi Valdez-Mondragón from Oaxaca, Mexico is provided, as well as the redescription of the male. This paper provides a cladistic reanalysis of the spider genus Physocyclus Simon, corroborating the monophyly of the genus with morphological data. The phylogenetic reanalysis was done with 54 morphological characters (44 binary and 10 multistate) using equal and implied weighting approach. The equal weighting analysis found two most parsimonious trees, whereas the analysis with implied weighting found just one most parsimonious trees with the concavity values (K= 5-10). The genus Physocyclus is composed by two clades or species groups: the globosus and the dugesi groups. Physocyclus peribanensis sp. nov. belongs to the dugesi group composed of 21 species, and P. paredesi to the globosus group composed of 11 species. With the new species described here, the number of known species of the genus Physocyclus increases to 32 species. The globosus group has a biogeographical distribution pattern in the Mesoamerican and Mexican Mountain biotic components, whereas the dugesi group has a biogeographical distribution in the Mesoamerican and Continental Nearctic biotic components. PMID:25283655

  9. A reanalysis of the morphological phylogeny of the spider genus Physocyclus Simon (Araneae: Pholcidae) with the description of a new species and description of the female of Physocyclus paredesi Valdez-Mondragón from Mexico.

    PubMed

    Valdez-Mondragón, Alejandro

    2014-01-01

    A new species of spider from Michoacán, Physocyclus peribanensis sp. nov. is described. This description is based on a male holotype and one female paratype. Also, the first description of the female of Physocyclus paredesi Valdez-Mondragón from Oaxaca, Mexico is provided, as well as the redescription of the male. This paper provides a cladistic reanalysis of the spider genus Physocyclus Simon, corroborating the monophyly of the genus with morphological data. The phylogenetic reanalysis was done with 54 morphological characters (44 binary and 10 multistate) using equal and implied weighting approach. The equal weighting analysis found two most parsimonious trees, whereas the analysis with implied weighting found just one most parsimonious trees with the concavity values (K= 5-10). The genus Physocyclus is composed by two clades or species groups: the globosus and the dugesi groups. Physocyclus peribanensis sp. nov. belongs to the dugesi group composed of 21 species, and P. paredesi to the globosus group composed of 11 species. With the new species described here, the number of known species of the genus Physocyclus increases to 32 species. The globosus group has a biogeographical distribution pattern in the Mesoamerican and Mexican Mountain biotic components, whereas the dugesi group has a biogeographical distribution in the Mesoamerican and Continental Nearctic biotic components.

  10. Spider behaviors include oral sexual encounters.

    PubMed

    Gregorič, Matjaž; Šuen, Klavdija; Cheng, Ren-Chung; Kralj-Fišer, Simona; Kuntner, Matjaž

    2016-01-01

    Several clades of spiders whose females evolved giant sizes are known for extreme sexual behaviors such as sexual cannibalism, opportunistic mating, mate-binding, genital mutilation, plugging, and emasculation. However, these behaviors have only been tested in a handful of size dimorphic spiders. Here, we bring another lineage into the picture by reporting on sexual behavior of Darwin's bark spider, Caerostris darwini. This sexually size dimorphic Madagascan species is known for extreme web gigantism and for producing the world's toughest biomaterial. Our field and laboratory study uncovers a rich sexual repertoire that predictably involves cannibalism, genital mutilation, male preference for teneral females, and emasculation. Surprisingly, C. darwini males engage in oral sexual encounters, rarely reported outside mammals. Irrespective of female's age or mating status males salivate onto female genitalia pre-, during, and post-copulation. While its adaptive significance is elusive, oral sexual contact in spiders may signal male quality or reduce sperm competition. PMID:27126507

  11. Spider behaviors include oral sexual encounters

    PubMed Central

    Gregorič, Matjaž; Šuen, Klavdija; Cheng, Ren-Chung; Kralj-Fišer, Simona; Kuntner, Matjaž

    2016-01-01

    Several clades of spiders whose females evolved giant sizes are known for extreme sexual behaviors such as sexual cannibalism, opportunistic mating, mate-binding, genital mutilation, plugging, and emasculation. However, these behaviors have only been tested in a handful of size dimorphic spiders. Here, we bring another lineage into the picture by reporting on sexual behavior of Darwin’s bark spider, Caerostris darwini. This sexually size dimorphic Madagascan species is known for extreme web gigantism and for producing the world’s toughest biomaterial. Our field and laboratory study uncovers a rich sexual repertoire that predictably involves cannibalism, genital mutilation, male preference for teneral females, and emasculation. Surprisingly, C. darwini males engage in oral sexual encounters, rarely reported outside mammals. Irrespective of female’s age or mating status males salivate onto female genitalia pre-, during, and post-copulation. While its adaptive significance is elusive, oral sexual contact in spiders may signal male quality or reduce sperm competition. PMID:27126507

  12. A redescription of the type species of the jumping spider genus Pseudomaevia (Araneae: Salticidae) from Lord Howe Island, Australia.

    PubMed

    Richardson, Barry J

    2014-01-01

    The genus Pseudomaevia Rainbow, 1920 presently includes three forms, P. cognata Rainbow, 1920, P. insulana Berland, 1942 and P. i. aorai Berland, 1942, all found in the western Pacific region (Platnick 2014). The type species, P. cognata, was only briefly described with some poor illustrations of the male, but no information was given on the female. This situation makes placing species in this genus, or the genus in a wider context, difficult. The present work describes and illustrates both sexes of the type species. The female genitalia are unusual in that the insemination duct joins the fertilization duct without any apparent spermatheca. The subfamilial placement of the genus is unknown.

  13. A redescription of the type species of the jumping spider genus Pseudomaevia (Araneae: Salticidae) from Lord Howe Island, Australia.

    PubMed

    Richardson, Barry J

    2014-01-01

    The genus Pseudomaevia Rainbow, 1920 presently includes three forms, P. cognata Rainbow, 1920, P. insulana Berland, 1942 and P. i. aorai Berland, 1942, all found in the western Pacific region (Platnick 2014). The type species, P. cognata, was only briefly described with some poor illustrations of the male, but no information was given on the female. This situation makes placing species in this genus, or the genus in a wider context, difficult. The present work describes and illustrates both sexes of the type species. The female genitalia are unusual in that the insemination duct joins the fertilization duct without any apparent spermatheca. The subfamilial placement of the genus is unknown. PMID:24943177

  14. Attending to detail by communal spider-eating spiders.

    PubMed

    Jackson, Robert R; Nelson, Ximena J

    2012-07-01

    Communal predators may often need to make especially intricate foraging decisions, as a predator's success may depend on the actions of its neighbours. Here,we consider the decisions made by Portia africana, a jumping spider (Salticidae) that preys on other spiders, including Oecobius amboseli (Oecobiidae), a small prey spider that lives under small sheets of silk (nests) on the walls of buildings. P. africana juveniles settle near oecobiid nests and then ambush oecobiids as they leave or enter the nest. Two or more P. africana juveniles sometimes settle at the same nest and, when an oecobiid is captured, the P. africana juveniles may share the meal. We investigated the joining decisions made by naïve P. africana juveniles. Experiments were based on using lures (dead spiders positioned in lifelike posture) arranged in a series of 17 different scenes defined by the presence/absence of a nest, the lure types present and the configuration of the lures and the nest. Our findings imply that P. africana juveniles make remarkably precise predatory decisions, with the variables that matter including whether a nest is present, the identity of spiders inside and outside a nest and how spiders are positioned relative to each other and the nest.

  15. Attending to detail by communal spider-eating spiders.

    PubMed

    Jackson, Robert R; Nelson, Ximena J

    2012-07-01

    Communal predators may often need to make especially intricate foraging decisions, as a predator's success may depend on the actions of its neighbours. Here,we consider the decisions made by Portia africana, a jumping spider (Salticidae) that preys on other spiders, including Oecobius amboseli (Oecobiidae), a small prey spider that lives under small sheets of silk (nests) on the walls of buildings. P. africana juveniles settle near oecobiid nests and then ambush oecobiids as they leave or enter the nest. Two or more P. africana juveniles sometimes settle at the same nest and, when an oecobiid is captured, the P. africana juveniles may share the meal. We investigated the joining decisions made by naïve P. africana juveniles. Experiments were based on using lures (dead spiders positioned in lifelike posture) arranged in a series of 17 different scenes defined by the presence/absence of a nest, the lure types present and the configuration of the lures and the nest. Our findings imply that P. africana juveniles make remarkably precise predatory decisions, with the variables that matter including whether a nest is present, the identity of spiders inside and outside a nest and how spiders are positioned relative to each other and the nest. PMID:22286279

  16. A two year study of verified spider bites in Switzerland and a review of the European spider bite literature.

    PubMed

    Nentwig, Wolfgang; Gnädinger, Markus; Fuchs, Joan; Ceschi, Alessandro

    2013-10-01

    During a two-year study, all spider bites recorded by Swiss primary care physicians were reported to the Swiss Toxicological Information Centre and all collected spiders were identified. A total of 14 verified spider bites were recorded, involving five species from four families: Zoropsis spinimana (five cases), Cheiracanthium punctorium (four cases), Tegenaria atrica (three cases) and one case of Malthonica ferruginea (= Tegenaria ferruginea) (both Agelenidae), and one case of Amaurobius ferox (Amaurobiidae). The bites of all spider species produced relatively mild symptoms. Local symptoms such as moderate to severe pain, circumscribed swelling and redness were the only effects in most cases. Systemic symptoms were rare. There was complete recovery in all cases and all lesions healed completely without further damage or secondary disorders. Following a review of the European spider bite literature, the number of spider species capable of biting humans in Europe is considered to be much larger than could be concluded from this study. Most spider bites are restricted to species living synanthropically, thus promoted by climate and habitat change. The annual frequency of spider bites in Switzerland is estimated at 10-100 bites per million inhabitants, but this is predicted to increase due to the continuous arrival of new alien species, many of which have a high potential to establish in urban areas. PMID:23872119

  17. The first record of the wolf spider subfamily Zoicinae from China (Araneae: Lycosidae), with the description of two new species.

    PubMed

    Li, Zongxu; Wang, Lu-yu; Zhangi, Zhi-sheng

    2013-01-01

    The subfamily Zoicinae Lehtinen & Hippa, 1979 is here first recorded from China with the description of a new species in the genus Zoica Simon, 1898, Z. unciformis sp. nov. from Wild Elephant Valley (Yunnan) and a new species in the genus Lysania Thorell, 1890, L. deangia sp. nov., from a rubber plantation in Nangsang Village (Yunnan). Lysania pygmaea Thorell, 1890 is recorded for the first time in China, from three localities in Yunnan and Guangxi and is redescribed here.

  18. Funnel-web spider bite

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002844.htm Funnel-web spider bite To use the sharing features on ... the effects of a bite from the funnel-web spider. Male funnel-web spiders are more poisonous ...

  19. Uncovering changes in spider orb-web topology owing to aerodynamic effects

    PubMed Central

    Zaera, Ramón; Soler, Alejandro; Teus, Jaime

    2014-01-01

    An orb-weaving spider's likelihood of survival is influenced by its ability to retain prey with minimum damage to its web and at the lowest manufacturing cost. This set of requirements has forced the spider silk to evolve towards extreme strength and ductility to a degree that is rare among materials. Previous studies reveal that the performance of the web upon impact may not be based on the mechanical properties of silk alone, aerodynamic drag could play a role in the dissipation of the prey's energy. Here, we present a thorough analysis of the effect of the aerodynamic drag on wind load and prey impact. The hypothesis considered by previous authors for the evaluation of the drag force per unit length of thread has been revisited according to well-established principles of fluid mechanics, highlighting the functional dependence on thread diameter that was formerly ignored. Theoretical analysis and finite-element simulations permitted us to identify air drag as a relevant factor in reducing deterioration of the orb web, and to reveal how the spider can take greater—and not negligible—advantage of drag dissipation. The study shows the beneficial air drag effects of building smaller and less dense webs under wind load, and larger and denser webs under prey impact loads. In essence, it points out why the aerodynamics need to be considered as an additional driving force in the evolution of silk threads and orb webs. PMID:24966235

  20. Uncovering changes in spider orb-web topology owing to aerodynamic effects.

    PubMed

    Zaera, Ramón; Soler, Alejandro; Teus, Jaime

    2014-09-01

    An orb-weaving spider's likelihood of survival is influenced by its ability to retain prey with minimum damage to its web and at the lowest manufacturing cost. This set of requirements has forced the spider silk to evolve towards extreme strength and ductility to a degree that is rare among materials. Previous studies reveal that the performance of the web upon impact may not be based on the mechanical properties of silk alone, aerodynamic drag could play a role in the dissipation of the prey's energy. Here, we present a thorough analysis of the effect of the aerodynamic drag on wind load and prey impact. The hypothesis considered by previous authors for the evaluation of the drag force per unit length of thread has been revisited according to well-established principles of fluid mechanics, highlighting the functional dependence on thread diameter that was formerly ignored. Theoretical analysis and finite-element simulations permitted us to identify air drag as a relevant factor in reducing deterioration of the orb web, and to reveal how the spider can take greater-and not negligible-advantage of drag dissipation. The study shows the beneficial air drag effects of building smaller and less dense webs under wind load, and larger and denser webs under prey impact loads. In essence, it points out why the aerodynamics need to be considered as an additional driving force in the evolution of silk threads and orb webs.

  1. The SPIDER CMB polarimeter

    NASA Astrophysics Data System (ADS)

    Trangsrud, Amy R.

    SPIDER is a balloon-borne millimeter-wave telescope designed to study the polarization of the Cosmic Microwave Background (CMB). SPIDER will map 10% of the full sky with degree-scale beams to search for the distinctive inflationary gravitational wave signal on angular scales between 1 degree and 10 degrees, thereby probing the energy scale of inflation. In its first flight, SPIDER will field 2,400 antenna-coupled bolometers split between two bands centered at 93 GHz and 148 GHz. Slot antenna arrays, band defining microstrip filters and superconducting bolometers are all fabricated photolithographically on a shared silicon substrate. SPIDER's detectors are split amongst six monochromatic on-axis refractors in a shared helium-cooled cryostat. This thesis reviews the design of SPIDER and its antenna-coupled bolometers, and details the currently achieved performance of SPIDER's receivers.

  2. Spider Web DNA: A New Spin on Noninvasive Genetics of Predator and Prey

    PubMed Central

    Xu, Charles C. Y.; Yen, Ivy J.; Bowman, Dean; Turner, Cameron R.

    2015-01-01

    Noninvasive genetic sampling enables biomonitoring without the need to directly observe or disturb target organisms. This paper describes a novel and promising source of noninvasive spider and insect DNA from spider webs. Using black widow spiders (Latrodectus spp.) fed with house crickets (Acheta domesticus), we successfully extracted, amplified, and sequenced mitochondrial DNA from spider web samples that identified both spider and prey to species. Detectability of spider DNA did not differ between assays with amplicon sizes from 135 to 497 base pairs. Spider and prey DNA remained detectable at least 88 days after living organisms were no longer present on the web. Spider web DNA as a proof-of-concept may open doors to other practical applications in conservation research, pest management, biogeography studies, and biodiversity assessments. PMID:26606730

  3. 'Spider' in Earth Orbit

    NASA Technical Reports Server (NTRS)

    1969-01-01

    View of the Apollo 9 Lunar Module 'Spider' in a lunar landing configuration photographed by Command Module pilot David Scott inside the Command/Service Module 'Gumdrop' on the fifth day of the Apollo 9 earth-orbital mission. The landing gear on 'Spider' has been deployed. lunar surface probes (sensors) extend out from the landing gear foot pads. Inside the 'Spider' were astronauts James A. McDivitt, Apollo 9 Commander; and Russell L. Schweickart, Lunar Module pilot.

  4. Ecosystem services in the face of invasion: the persistence of native and nonnative spiders in an agricultural landscape.

    PubMed

    Hogg, Brian N; Daane, Kent M

    2011-03-01

    The presence of intact natural ecosystems in agricultural landscapes can mitigate losses in the diversity of natural enemies and enhance ecosystem services. However, native natural enemies may fail to persist in agroecosystems if invaders dominate species interactions. In this study, native and nonnative spiders were sampled along transects that extended from oak woodland and riparian zones into surrounding California vineyards, to assess the role of natural habitat as a source for spider biodiversity in the vineyard landscape, and to compare the dominance of exotic Cheiracanthium spiders between habitats. Many spider species were more abundant in natural habitat than in vineyards, and numbers of spiders and spider species within vineyards were higher at the vineyard edge adjacent to oak woodland. These results suggest that natural habitat is a key source for spiders in vineyards. The positive effect of oak woodland on the vineyard spider community extended only to the vineyard edge, however. Proportions of Cheiracanthium spiders increased dramatically in the vineyard, while numbers of native wandering spiders (the native ecological homologues of Cheiracanthium spiders) decreased. Dispersal limitation and strong habitat preferences may have prevented native wandering spiders from establishing far from the vineyard edge. Exotic Cheiracanthium spiders, in contrast, may possess specific adaptations to vineyards or to a wide range of habitats. Results suggest that the ecosystem services provided by intact natural habitat may be limited in agricultural landscapes that are dominated by invasive species.

  5. Disentangling the Phylogenetic and Ecological Components of Spider Phenotypic Variation

    PubMed Central

    Gonçalves-Souza, Thiago; Diniz-Filho, José Alexandre Felizola; Romero, Gustavo Quevedo

    2014-01-01

    An understanding of how the degree of phylogenetic relatedness influences the ecological similarity among species is crucial to inferring the mechanisms governing the assembly of communities. We evaluated the relative importance of spider phylogenetic relationships and ecological niche (plant morphological variables) to the variation in spider body size and shape by comparing spiders at different scales: (i) between bromeliads and dicot plants (i.e., habitat scale) and (ii) among bromeliads with distinct architectural features (i.e., microhabitat scale). We partitioned the interspecific variation in body size and shape into phylogenetic (that express trait values as expected by phylogenetic relationships among species) and ecological components (that express trait values independent of phylogenetic relationships). At the habitat scale, bromeliad spiders were larger and flatter than spiders associated with the surrounding dicots. At this scale, plant morphology sorted out close related spiders. Our results showed that spider flatness is phylogenetically clustered at the habitat scale, whereas it is phylogenetically overdispersed at the microhabitat scale, although phylogenic signal is present in both scales. Taken together, these results suggest that whereas at the habitat scale selective colonization affect spider body size and shape, at fine scales both selective colonization and adaptive evolution determine spider body shape. By partitioning the phylogenetic and ecological components of phenotypic variation, we were able to disentangle the evolutionary history of distinct spider traits and show that plant architecture plays a role in the evolution of spider body size and shape. We also discussed the relevance in considering multiple scales when studying phylogenetic community structure. PMID:24651264

  6. Disentangling the phylogenetic and ecological components of spider phenotypic variation.

    PubMed

    Gonçalves-Souza, Thiago; Diniz-Filho, José Alexandre Felizola; Romero, Gustavo Quevedo

    2014-01-01

    An understanding of how the degree of phylogenetic relatedness influences the ecological similarity among species is crucial to inferring the mechanisms governing the assembly of communities. We evaluated the relative importance of spider phylogenetic relationships and ecological niche (plant morphological variables) to the variation in spider body size and shape by comparing spiders at different scales: (i) between bromeliads and dicot plants (i.e., habitat scale) and (ii) among bromeliads with distinct architectural features (i.e., microhabitat scale). We partitioned the interspecific variation in body size and shape into phylogenetic (that express trait values as expected by phylogenetic relationships among species) and ecological components (that express trait values independent of phylogenetic relationships). At the habitat scale, bromeliad spiders were larger and flatter than spiders associated with the surrounding dicots. At this scale, plant morphology sorted out close related spiders. Our results showed that spider flatness is phylogenetically clustered at the habitat scale, whereas it is phylogenetically overdispersed at the microhabitat scale, although phylogenic signal is present in both scales. Taken together, these results suggest that whereas at the habitat scale selective colonization affect spider body size and shape, at fine scales both selective colonization and adaptive evolution determine spider body shape. By partitioning the phylogenetic and ecological components of phenotypic variation, we were able to disentangle the evolutionary history of distinct spider traits and show that plant architecture plays a role in the evolution of spider body size and shape. We also discussed the relevance in considering multiple scales when studying phylogenetic community structure. PMID:24651264

  7. Low temperature–scanning electron microscopy to evaluate morphology and predation of Scolothrips sexmaculatus Pergande (Thysanoptera: Thripidae) against spider mites (Acari: Tetranychidae: Tetranychus species)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper evaluates the potential usefulness of low temperature-scanning electron microscopy (LT-SEM) to evaluate morphology and predation behavior of the six-spotted thrips (Scolothrips sexmaculatus Pergande) against the two-spotted spider mite (Tetranychus urticae (Koch)). Morphological features...

  8. Scavenging by spiders (Araneae) and its relationship to pest management of the brown recluse spider.

    PubMed

    Vetter, Richard S

    2011-06-01

    Experiments reported in Sandidge (2003; Nature 426: 30) indicated that the brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, preferred to scavenge dead prey over live prey and that the spiders were not detrimentally affected when fed insecticide-killed crickets. Extrapolations made in subsequent media coverage disseminating the results of this research made counter-intuitive statements that pesticide treatment in houses would increase brown recluse populations in homes. This information was presented as if the scavenging behavior was specialized in the brown recluse; however, it was more likely that this behavior has not been well studied in other species. To provide a comparison, the current laboratory study examined the likelihood of non-Loxosceles spiders to scavenge dead prey. Of 100 non-Loxosceles spiders that were tested (from 11 families, 24 genera, and at least 29 species from a variety of spider hunting guilds), 99 scavenged dead crickets when offered in petri dishes. Some of the spiders were webspinners in which real-world scavenging of dead prey is virtually impossible, yet they scavenge when given the opportunity. Therefore, scavenging is a flexible opportunistic predatory behavior that is spread across a variety of taxa and is not a unique behavior in brown recluses. These findings are discussed in relation to pest management practices.

  9. A new species-complex within the trapdoor spider genus Nemesia Audouin 1826 distributed in northern and central Italy, with descriptions of three new species (Araneae, Mygalomorphae, Nemesiidae).

    PubMed

    Decae, Arthur; Pantini, Paolo; Isaia, Marco

    2015-12-23

    Three new Nemesia Audouin 1826 species from northern and central Italy are named. They share a combination of sexual characters, not found in other described species. A new species-complex within Nemesia is here referred to as the apenninica group. Within the apenninica group, N. apenninica n. sp., N. hastensis n. sp., and N. pedemontana n. sp. differ in the morphology of the male palpal organ and the female spermathecae. The three species have different kinds of geographical distributions. While N. apenninica and N. hastensis have locally restricted and geographically separated distributions, the distribution of N. pedemontana overlaps with that of both of these species and extends widely in northern and central Italy. In its periphery, the distribution of N. pedemontana overlaps with that of species other than the apenninica group, e.g., N. meridionalis (Costa, 1835) in southern Italy and N. manderstjernae (L. Koch, 1871) and N. carminans (Latreille, 1818) in Liguria. Information on burrow structure, phenology and habitat are provided for all three new species. Some aspects of the behavior and feeding are discussed for N. pedemontana and N. hastensis.

  10. Signal conflict in spider webs driven by predators and prey

    PubMed Central

    Blackledge, T. A.

    1998-01-01

    Variation in the sensory physiologies of organisms can bias the receptions of signals, driving the direction of signal evolution. Sensory drive in the evolution of signals may be particularly important for organisms that confront trade-offs in signal design between the need for conspicuousness to allow effective transfer of information and the need for crypsis of the signal to unintended receivers. Several genera of orb-weaving spiders include conspicuous silk designs, stabilimenta, in the centre of their webs. Stabilimenta can be highly visible signals to predators, warning them of the presence of a noxious, sticky silk web. However, stabilimenta can also be used by prey as a signal in avoidance of webs, creating a trade-off in signal visibility. I argue that the derived spectral properties of stabilimentum silk have resulted in part from this conflict. The innate colour preferences of insects, their ability to learn colours, and the spectral properties of flowers all suggest that the reflectance spectra of stabilimenta renders them relatively cryptic to many insect prey, while maintaining their visibility to vertebrate predators.

  11. Insects and Spiders.

    ERIC Educational Resources Information Center

    National Audubon Society, New York, NY.

    This set of teaching aids consists of nine Audubon Nature Bulletins, providing teachers and students with informational reading on insects and spiders. The bulletins have these titles: What Good Are Insects, How Insects Benefit Man, Life of the Honey Bee, Ants and Their Fascinating Ways, Mosquitoes and Other Flies, Caterpillars, Spiders and Silk,…

  12. Becoming a Spider Scientist

    ERIC Educational Resources Information Center

    Patrick, Patricia; Getz, Angela

    2008-01-01

    In this integrated unit, third grade students become spider scientists as they observe spiders in their classroom to debunk some common misconceptions about these intimidating creatures. "Charlotte's Web" is used to capture students' interest. In addition to addressing philosophical topics such as growing-up, death, and friendship; E.B. White's…

  13. Wolf spider envenomation.

    PubMed

    Livshits, Zhanna; Bernstein, Benjamin; Sorkin, Louis N; Smith, Silas W; Hoffman, Robert S

    2012-03-01

    Although wolf spider venom has been implicated in necrotic arachnidism without acceptably documented verification, limited, prospectively collected data demonstrate a lack of cutaneous necrosis. The infrequent nature of exposure and inherent difficulty in confirming wolf spider bites in humans makes it challenging to study such envenomations. We present the case of a 20 year-old man with confirmed exposure to the wolf spider who developed cutaneous erythema with ulceration following the bite. There was no evidence of skin necrosis. He was treated with aggressive wound care and systemic antibiotics for wound infection, with subsequent resolution of symptoms. This case adds to the limited knowledge regarding wolf spider envenomations and describes the clinical effects and management of wolf spider envenomation.

  14. Beat sampling accuracy in estimating spruce spider mite (Acari: Tetranychidae) populations and injury on juniper.

    PubMed

    Shrewsbury, Paula M; Hardin, Mark R

    2004-08-01

    The use of a standardized beat sampling method for estimating spruce spider mite, Oligonychus ununguis (Jacobi) (Acari: Tetranychidae), densities on a widely used evergreen ornamental plant species, Juniperus chinensis variety 'Sargentii' A. Henry (Cupressaceae), was examined. There was a significant positive relationship between total spruce spider mite densities and spider mite densities from beat sampling on juniper. The slope and intercept of the relationship may be used by pest managers to predict total spider mite densities on plants from beat sample counts. Beat sampling dramatically underestimates the total number of spider mites on a foliage sample. The relationships between spruce spider mite feeding injury and spider mite density estimates from beat sampling juniper foliage and total spider mite counts on foliage were also examined. There was a significant positive relationship between spruce spider mite density as estimated from beat sampling and injury to the plants. There was a similar positive relationship between the total number of spruce spider mites and injury to the plants, suggesting that a pest manager could use beat sampling counts to estimate plant injury and related thresholds. These findings have important implications to decision-making for spruce spider mite control, especially as it relates to threshold levels and determining rates of predator releases. Further assessment of the effectiveness of beat and other sampling methods across multiple spider mite- host plant associations needs to be examined to enable pest managers to select sampling plans that are feasible and reliable.

  15. Salticid predation as one potential driving force of ant mimicry in jumping spiders.

    PubMed

    Huang, Jin-Nan; Cheng, Ren-Chung; Li, Daiqin; Tso, I-Min

    2011-05-01

    Many spiders possess myrmecomorphy, and species of the jumping spider genus Myrmarachne exhibit nearly perfect ant mimicry. Most salticids are diurnal predators with unusually high visual acuity that prey on various arthropods, including conspecifics. In this study, we tested whether predation pressure from large jumping spiders is one possible driving force of perfect ant mimicry in jumping spiders. The results showed that small non-ant-mimicking jumping spiders were readily treated as prey by large ones (no matter whether heterospecific or conspecific) and suffered high attack and mortality rates. The size difference between small and large jumping spiders significantly affected the outcomes of predatory interactions between them: the smaller the juvenile jumping spiders, the higher the predation risk from large ones. The attack and mortality rates of ant-mimicking jumping spiders were significantly lower than those of non-ant-mimicking jumping spiders, indicating that a resemblance to ants could provide protection against salticid predation. However, results of multivariate behavioural analyses showed that the responses of large jumping spiders to ants and ant-mimicking salticids differed significantly. Results of this study indicate that predation pressure from large jumping spiders might be one selection force driving the evolution of nearly perfect myrmecomorphy in spiders and other arthropods.

  16. Salticid predation as one potential driving force of ant mimicry in jumping spiders.

    PubMed

    Huang, Jin-Nan; Cheng, Ren-Chung; Li, Daiqin; Tso, I-Min

    2011-05-01

    Many spiders possess myrmecomorphy, and species of the jumping spider genus Myrmarachne exhibit nearly perfect ant mimicry. Most salticids are diurnal predators with unusually high visual acuity that prey on various arthropods, including conspecifics. In this study, we tested whether predation pressure from large jumping spiders is one possible driving force of perfect ant mimicry in jumping spiders. The results showed that small non-ant-mimicking jumping spiders were readily treated as prey by large ones (no matter whether heterospecific or conspecific) and suffered high attack and mortality rates. The size difference between small and large jumping spiders significantly affected the outcomes of predatory interactions between them: the smaller the juvenile jumping spiders, the higher the predation risk from large ones. The attack and mortality rates of ant-mimicking jumping spiders were significantly lower than those of non-ant-mimicking jumping spiders, indicating that a resemblance to ants could provide protection against salticid predation. However, results of multivariate behavioural analyses showed that the responses of large jumping spiders to ants and ant-mimicking salticids differed significantly. Results of this study indicate that predation pressure from large jumping spiders might be one selection force driving the evolution of nearly perfect myrmecomorphy in spiders and other arthropods. PMID:20961898

  17. Salticid predation as one potential driving force of ant mimicry in jumping spiders

    PubMed Central

    Huang, Jin-Nan; Cheng, Ren-Chung; Li, Daiqin; Tso, I-Min

    2011-01-01

    Many spiders possess myrmecomorphy, and species of the jumping spider genus Myrmarachne exhibit nearly perfect ant mimicry. Most salticids are diurnal predators with unusually high visual acuity that prey on various arthropods, including conspecifics. In this study, we tested whether predation pressure from large jumping spiders is one possible driving force of perfect ant mimicry in jumping spiders. The results showed that small non-ant-mimicking jumping spiders were readily treated as prey by large ones (no matter whether heterospecific or conspecific) and suffered high attack and mortality rates. The size difference between small and large jumping spiders significantly affected the outcomes of predatory interactions between them: the smaller the juvenile jumping spiders, the higher the predation risk from large ones. The attack and mortality rates of ant-mimicking jumping spiders were significantly lower than those of non-ant-mimicking jumping spiders, indicating that a resemblance to ants could provide protection against salticid predation. However, results of multivariate behavioural analyses showed that the responses of large jumping spiders to ants and ant-mimicking salticids differed significantly. Results of this study indicate that predation pressure from large jumping spiders might be one selection force driving the evolution of nearly perfect myrmecomorphy in spiders and other arthropods. PMID:20961898

  18. Spiders Tune Glue Viscosity to Maximize Adhesion.

    PubMed

    Amarpuri, Gaurav; Zhang, Ci; Diaz, Candido; Opell, Brent D; Blackledge, Todd A; Dhinojwala, Ali

    2015-11-24

    Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives.

  19. Spiders Tune Glue Viscosity to Maximize Adhesion.

    PubMed

    Amarpuri, Gaurav; Zhang, Ci; Diaz, Candido; Opell, Brent D; Blackledge, Todd A; Dhinojwala, Ali

    2015-11-24

    Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives. PMID:26513350

  20. Biodiversity baseline of the French Guiana spider fauna.

    PubMed

    Vedel, Vincent; Rheims, Christina; Murienne, Jérôme; Brescovit, Antonio Domingos

    2013-01-01

    The need for an updated list of spiders found in French Guiana rose recently due to many upcoming studies planned. In this paper, we list spiders from French Guiana from existing literature (with corrected nomenclature when necessary) and from 2142 spiders sampled in 12 sites for this baseline study. Three hundred and sixty four validated species names of spider were found in the literature and previous authors' works. Additional sampling, conducted for this study added another 89 identified species and 62 other species with only a genus name for now. The total species of spiders sampled in French Guiana is currently 515. Many other Morphospecies were found but not described as species yet. An accumulation curve was drawn with seven of the sampling sites and shows no plateau yet. Therefore, the number of species inhabiting French Guiana cannot yet be determined. As the very large number of singletons found in the collected materials suggests, the accumulation curve indicates nevertheless that more sampling is necessary to discover the many unknown spider species living in French Guiana, with a focus on specific periods (dry season and wet season) and on specific and poorly studied habitats such as canopy, inselberg and cambrouze (local bamboo monospecific forest).

  1. The first account of a bite by the New Zealand native spider Trite planiceps (Araneae: Salticidae).

    PubMed

    Derraik, José G B; Sirvid, Phil J; Rademaker, Marius

    2010-05-14

    New Zealand has very few arthropods that pose a threat to human health. While most New Zealand spiders are considered harmless, the bite effects of most species are unknown. Here, we describe a case of a bite by a native spider, in which a young man was bitten after rolling over in his bed. The spider was collected and identified as Trite planiceps (Salticidae, black headed jumping spider), a native species commonly encountered around homes. The initial reaction was a relatively painful, sting-like, sensation, followed by the appearance of two red puncture marks and an urticarial wheal. Symptoms eventually disappeared after 72 hours, and he has had no further dermatological problems. Trite planiceps is considered to be a rather docile spider with regard to humans, but even a docile species may still bite defensively as a last resort. Notes on this species and on treatment of spider bites are provided. PMID:20581919

  2. Assessing and managing spider and scorpion envenomation.

    PubMed

    McGhee, Stephen; Weiner, Aaron; Finnegan, Alan; Visovsky, Constance; Clochesy, John M; Graves, Brian

    2015-11-01

    Envenomation by spiders or scorpions is a public health problem in many parts of the world and is not isolated to the tropics and subtropics. Spiders and scorpions can be unintentionally transported globally, and keeping them as pets is becoming more popular, so envenomation can occur anywhere. Emergency nurses should be prepared to assess and treat patients who present with a bite or sting. This article gives an overview of the signs, symptoms and treatment of envenomation by species of arachnids that are clinically significant to humans.

  3. Assessing and managing spider and scorpion envenomation.

    PubMed

    McGhee, Stephen; Weiner, Aaron; Finnegan, Alan; Visovsky, Constance; Clochesy, John M; Graves, Brian

    2015-11-01

    Envenomation by spiders or scorpions is a public health problem in many parts of the world and is not isolated to the tropics and subtropics. Spiders and scorpions can be unintentionally transported globally, and keeping them as pets is becoming more popular, so envenomation can occur anywhere. Emergency nurses should be prepared to assess and treat patients who present with a bite or sting. This article gives an overview of the signs, symptoms and treatment of envenomation by species of arachnids that are clinically significant to humans. PMID:26542925

  4. Comparing rates of springtail predation by web-building spiders using Bayesian inference.

    PubMed

    Welch, Kelton D; Schofield, Matthew R; Chapman, Eric G; Harwood, James D

    2014-08-01

    A major goal of gut-content analysis is to quantify predation rates by predators in the field, which could provide insights into the mechanisms behind ecosystem structure and function, as well as quantification of ecosystem services provided. However, percentage-positive results from molecular assays are strongly influenced by factors other than predation rate, and thus can only be reliably used to quantify predation rates under very restrictive conditions. Here, we develop two statistical approaches, one using a parametric bootstrap and the other in terms of Bayesian inference, to build upon previous techniques that use DNA decay rates to rank predators by their rate of prey consumption, by allowing a statistical assessment of confidence in the inferred ranking. To demonstrate the utility of this technique in evaluating ecological data, we test web-building spiders for predation on a primary prey item, springtails. Using these approaches we found that an orb-weaving spider consumes springtail prey at a higher rate than a syntopic sheet-weaving spider, despite occupying microhabitats where springtails are less frequently encountered. We suggest that spider-web architecture (orb web vs. sheet web) is a primary determinant of prey-consumption rates within this assemblage of predators, which demonstrates the potential influence of predator foraging behaviour on trophic web structure. We also discuss how additional assumptions can be incorporated into the same analysis to allow broader application of the technique beyond the specific example presented. We believe that such modelling techniques can greatly advance the field of molecular gut-content analysis. PMID:24635414

  5. Secondary eyes mediate the response to looming objects in jumping spiders (Phidippus audax, Salticidae).

    PubMed

    Spano, Lauren; Long, Skye M; Jakob, Elizabeth M

    2012-12-23

    Some species have sensory systems divided into subsystems with morphologically different sense organs that acquire different types of information within the same modality. Jumping spiders (family Salticidae) have eight eyes. Four eyes are directed anteriorly to view objects in front of the spider: a pair of principal eyes track targets with their movable retinae, while the immobile anterior lateral (AL) eyes have a larger field of view and lower resolution. To test whether the principal eyes, the AL eyes, or both together mediate the response to looming stimuli, we presented spiders with a video of a solid black circle that rapidly expanded (loomed) or contracted (receded). Control spiders and spiders with their principal eyes masked were significantly more likely to back away from the looming stimulus than were spiders with their AL eyes masked. Almost no individuals backed away from the receding stimulus. Our results show that the AL eyes alone mediate the loom response to objects anterior to the spider. PMID:23075526

  6. Spider sex pheromones: emission, reception, structures, and functions.

    PubMed

    Gaskett, A C

    2007-02-01

    Spiders and their mating systems are useful study subjects with which to investigate questions of widespread interest about sexual selection, pre- and post-copulatory mate choice, sperm competition, mating strategies, and sexual conflict. Conclusions drawn from such studies are broadly applicable to a range of taxa, but rely on accurate understanding of spider sexual interactions. Extensive behavioural experimentation demonstrates the presence of sex pheromones in many spider species, and recent major advances in the identification of spider sex pheromones merit review. Synthesised here are the emission, transmission, structures, and functions of spider sex pheromones, with emphasis on the crucial and dynamic role of sex pheromones in female and male mating strategies generally. Techniques for behavioural, chemical and electrophysiological study are summarised, and I aim to provide guidelines for incorporating sex pheromones into future studies of spider mating. In the spiders, pheromones are generally emitted by females and received by males, but this pattern is not universal. Female spiders emit cuticular and/or silk-based sex pheromones, which can be airborne or received via contact with chemoreceptors on male pedipalps. Airborne pheromones primarily attract males or elicit male searching behaviour. Contact pheromones stimulate male courtship behaviour and provide specific information about the emitter's identity. Male spiders are generally choosy and are often most attracted to adult virgin females and juvenile females prior to their final moult. This suggests the first male to mate with a female has significant advantages, perhaps due to sperm priority patterns, or mated female disinterest. Both sexes may attempt to control female pheromone emission, and thus dictate the frequency and timing of female mating, reflecting the potentially different costs of female signalling and/or polyandry to both sexes. Spider sex pheromones are likely to be lipids or lipid

  7. A comparison of spider communities in Bt and non-Bt rice fields.

    PubMed

    Lee, Sue Yeon; Kim, Seung Tae; Jung, Jong Kook; Lee, Joon-Ho

    2014-06-01

    To assess the potential adverse effects of a Bt rice line (Japonica rice cultivar, Nakdong) expressing a synthetic cry1Ac1 gene, C7-1-9-1-B, which was highly active against all larval stages of Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Crambidae), we investigated the community structure of spiders in Bt and non-Bt rice fields during the rice-growing season in 2007 and 2008 in Chungcheongnam-do, Korea. Spiders were surveyed with a sweep net and suction device. Suction sampling captured more spiders, measured in terms of species level and abundance, than sweeping. Araneidae and Thomisidae were captured more by sweeping, and certain species were captured only by sweeping. These findings show that both suction and sweep sampling methods should be used because these methods are most likely complementary. In total, 29 species in 23 genera and nine families were identified from the 4,937 spiders collected, and both Bt and non-Bt rice fields showed a typical Korean spider assemblage. The temporal patterns of spider species richness and spider abundance were very similar between Bt and non-Bt rice, although significant differences in species richness were observed on a few occasions. Overall, spider community structure, including diversity, the dominant species, and abundance did not differ between Bt and non-Bt rice. The results of the study indicated that the transgenic Cry1Ac rice lines tested in this study had no adverse effects on the spider community structure of the rice fields.

  8. Mermithid parasitism of Hawaiian Tetragnatha spiders in a fragmented landscape

    USGS Publications Warehouse

    Vandergast, Amy; Roderick, George K.

    2003-01-01

    Hawaiian Tetragnatha spiders inhabiting small forest fragments on the Big Island of Hawaii are parasitized by mermithid nematodes. This is the first report of mermithid nematodes infecting spiders in Hawaii, and an initial attempt to characterize this host–parasite interaction. Because immature mermithids were not morphologically identifiable, a molecular identification was performed. A phylogenetic analysis based on 18S small ribosomal subunit nuclear gene sequences suggested that Hawaiian spider mermithids are more closely related to a mainland presumptive Aranimemis species that infects spiders, than to an insect-infecting mermithid collected on Oahu, HI, or to Mermis nigrescens, also a parasite of insects. Measured infection prevalence was low (ranging from 0 to 4%) but differed significantly among forest fragments. Infection prevalence was associated significantly with fragment area, but not with spider density nor spider species richness. Results suggest that mermithid populations are sensitive to habitat fragmentation, but that changes in infection prevalence do not appear to affect spider community structure.

  9. Brown recluse spider

    MedlinePlus

    ... recluse spider prefers dark, sheltered areas such as under porches and in woodpiles. ... preferred hiding places, such as dark, sheltered areas under logs or underbrush, or other damp, moist areas.

  10. Space spider crane

    NASA Technical Reports Server (NTRS)

    Macconochie, Ian O. (Inventor); Mikulas, Martin M., Jr. (Inventor); Pennington, Jack E. (Inventor); Kinkead, Rebecca L. (Inventor); Bryan, Charles F., Jr. (Inventor)

    1988-01-01

    A space spider crane for the movement, placement, and or assembly of various components on or in the vicinity of a space structure is described. As permanent space structures are utilized by the space program, a means will be required to transport cargo and perform various repair tasks. A space spider crane comprising a small central body with attached manipulators and legs fulfills this requirement. The manipulators may be equipped with constant pressure gripping end effectors or tools to accomplish various repair tasks. The legs are also equipped with constant pressure gripping end effectors to grip the space structure. Control of the space spider crane may be achieved either by computer software or a remotely situated human operator, who maintains visual contact via television cameras mounted on the space spider crane. One possible walking program consists of a parallel motion walking program whereby the small central body alternatively leans forward and backward relative to end effectors.

  11. Brown recluse spider (image)

    MedlinePlus

    The brown recluse is a venomous spider most commonly found in midwestern and southern states of the United States. ... inch overall and has long skinny legs. The brown recluse is brown with a characteristic dark violin- ...

  12. Spider fauna of semiarid eastern Colorado agroecosystems: diversity, abundance, and effects of crop intensification.

    PubMed

    Kerzicnik, Lauren M; Peairs, Frank B; Cushing, Paula E; Draney, Michael L; Merrill, Scott C

    2013-02-01

    Spiders are critical predators in agroecosystems. Crop management practices can influence predator density and diversity, which, in turn, can influence pest management strategies. Crop intensification is a sustainable agricultural technique that can enhance crop production although optimizing soil moisture. To date, there is no information on how crop intensification affects natural enemy populations, particularly spiders. This study had two objectives: to characterize the abundance and diversity of spiders in eastern Colorado agroecosystems, and to test the hypothesis that spider diversity and density would be higher in wheat (Triticum aestivum L.) in crop-intensified rotations compared with wheat in conventional rotations. We collected spiders through pitfall, vacuum, and lookdown sampling from 2002 to 2007 to test these objectives. Over 11,000 spiders in 19 families from 119 species were captured from all sampling techniques. Interestingly, the hunting spider guild represented 89% of the spider fauna captured from all sites with the families Gnaphosidae and Lycosidae representing 75% of these spiders. Compared with European agroecosystems, these agroecosystems had greater diversity, which can be beneficial for the biological control of pests. Overall, spider densities were low in these semiarid cropping systems, and crop intensification effects on spider densities were not evident at this scale.

  13. Spider fauna of semiarid eastern Colorado agroecosystems: diversity, abundance, and effects of crop intensification.

    PubMed

    Kerzicnik, Lauren M; Peairs, Frank B; Cushing, Paula E; Draney, Michael L; Merrill, Scott C

    2013-02-01

    Spiders are critical predators in agroecosystems. Crop management practices can influence predator density and diversity, which, in turn, can influence pest management strategies. Crop intensification is a sustainable agricultural technique that can enhance crop production although optimizing soil moisture. To date, there is no information on how crop intensification affects natural enemy populations, particularly spiders. This study had two objectives: to characterize the abundance and diversity of spiders in eastern Colorado agroecosystems, and to test the hypothesis that spider diversity and density would be higher in wheat (Triticum aestivum L.) in crop-intensified rotations compared with wheat in conventional rotations. We collected spiders through pitfall, vacuum, and lookdown sampling from 2002 to 2007 to test these objectives. Over 11,000 spiders in 19 families from 119 species were captured from all sampling techniques. Interestingly, the hunting spider guild represented 89% of the spider fauna captured from all sites with the families Gnaphosidae and Lycosidae representing 75% of these spiders. Compared with European agroecosystems, these agroecosystems had greater diversity, which can be beneficial for the biological control of pests. Overall, spider densities were low in these semiarid cropping systems, and crop intensification effects on spider densities were not evident at this scale. PMID:23339794

  14. Bird predation affects diurnal and nocturnal web-building spiders in a Mediterranean citrus grove

    NASA Astrophysics Data System (ADS)

    Mestre, L.; Garcia, N.; Barrientos, J. A.; Espadaler, X.; Piñol, J.

    2013-02-01

    Spiders and birds can greatly decrease insect populations, but birds also limit spider densities in some habitats. Bird predation is thought to be one of the causes behind nocturnal activity in spiders, so night-active spiders that hide in retreats during the day should be less affected by bird foraging than day-active spiders. However, this hypothesis has not yet been tested. We investigated the importance of bird predation on the spider community of a Mediterranean organic citrus grove. We excluded birds by placing net cages over the trees and we conducted visual searches in the canopies to sample web-building spiders. As there are many nocturnal species in the family Araneidae, we conducted searches both by day and by night to compare the abundance of active araneids in these two time periods. We sampled the tree trunks with cardboard bands to collect hunting spiders. In bird-excluded canopies there were more spiders of the families Araneidae and Theridiidae. There were higher numbers of active Araneidae at night, but these were just as negatively affected by bird predation as day-active Araneidae, so there was no evidence of nocturnal activity serving as an anti-predator strategy. We did not find any negative impact of birds on hunting spiders. Our results contrast with other studies reporting a negative effect of birds on hunting but not on web-building spiders.

  15. Spider Spinning for Dummies

    NASA Astrophysics Data System (ADS)

    Bird, Richard S.

    Spider spinning is a snappy name for the problem of listing the ideals of a totally acyclic poset in such a way that each ideal is computed from its predecessor in constant time. Such an algorithm is said to be loopless. Our aim in these lectures is to show how to calculate a loopless algorithm for spider spinning. The calculation makes use of the fundamental laws of functional programming and the real purpose of the exercise is to show these laws in action.

  16. Attentional bias to moving spiders in spider fearful individuals.

    PubMed

    Vrijsen, Janna N; Fleurkens, Pascal; Nieuwboer, Wieteke; Rinck, Mike

    2009-05-01

    We investigated if an attentional bias for spiders in spider fearful individuals (SFs) can also be found for moving spiders, rather than static images. In Study 1, 28 SFs and 33 non-anxious controls (NACs) participated in a modified version of the dot probe paradigm: they had to react to a probe that appeared either in the next, previous, or side position of a spider's or a wheel's path. 24 SFs and 29 NACs participated in Study 2, in which a fourth, highly predictable, probe position was added. We expected that moving spiders would capture the attention of SFs. In addition, we tested whether SFs try to predict the movement of the spider to make it less threatening. As expected, SFs showed an attentional bias towards moving spiders. However, both groups reacted fastest to unpredictable movements, indicating that SFs and NACs alike anticipate unpredictable spider movements.

  17. The Jean Gutierrez spider mite collection.

    PubMed

    Migeon, Alain

    2015-01-01

    The family Tetranychidae (spider mites) currently comprises 1,275 species and represents one of the most important agricultural pest families among the Acari with approximately one hundred pest species, ten of which considered major pests. The dataset presented in this document includes all the identified spider mites composing the Jean Gutierrez Collection hosted at the CBGP (Montferrier-sur-Lez, France), gathered from 1963 to 1999 during his career at the Institut de Recherche pour le Développement (IRD). It consists of 5,262 specimens corresponding to 1,564 occurrences (combination species/host plant/date/location) of 175 species. Most specimens were collected in Madagascar and other islands of the Western Indian Ocean, New Caledonia and other islands of the South Pacific and Papuasia. The dataset constitutes today the most important one available on Tetranychidae worldwide.

  18. Endosymbiont Dominated Bacterial Communities in a Dwarf Spider

    PubMed Central

    Vanthournout, Bram; Hendrickx, Frederik

    2015-01-01

    The microbial community of spiders is little known, with previous studies focussing primarily on the medical importance of spiders as vectors of pathogenic bacteria and on the screening of known cytoplasmic endosymbiont bacteria. These screening studies have been performed by means of specific primers that only amplify a selective set of endosymbionts, hampering the detection of unreported species in spiders. In order to have a more complete overview of the bacterial species that can be present in spiders, we applied a combination of a cloning assay, DGGE profiling and high-throughput sequencing on multiple individuals of the dwarf spider Oedothorax gibbosus. This revealed a co-infection of at least three known (Wolbachia, Rickettsia and Cardinium) and the detection of a previously unreported endosymbiont bacterium (Rhabdochlamydia) in spiders. 16S rRNA gene sequences of Rhabdochlamydia matched closely with those of Candidatus R. porcellionis, which is currently only reported as a pathogen from a woodlouse and with Candidatus R. crassificans reported from a cockroach. Remarkably, this bacterium appears to present in very high proportions in one of the two populations only, with all investigated females being infected. We also recovered Acinetobacter in high abundance in one individual. In total, more than 99% of approximately 4.5M high-throughput sequencing reads were restricted to these five bacterial species. In contrast to previously reported screening studies of terrestrial arthropods, our results suggest that the bacterial communities in this spider species are dominated by, or even restricted to endosymbiont bacteria. Given the high prevalence of endosymbiont species in spiders, this bacterial community pattern could be widespread in the Araneae order. PMID:25706947

  19. Endosymbiont dominated bacterial communities in a dwarf spider.

    PubMed

    Vanthournout, Bram; Hendrickx, Frederik

    2015-01-01

    The microbial community of spiders is little known, with previous studies focussing primarily on the medical importance of spiders as vectors of pathogenic bacteria and on the screening of known cytoplasmic endosymbiont bacteria. These screening studies have been performed by means of specific primers that only amplify a selective set of endosymbionts, hampering the detection of unreported species in spiders. In order to have a more complete overview of the bacterial species that can be present in spiders, we applied a combination of a cloning assay, DGGE profiling and high-throughput sequencing on multiple individuals of the dwarf spider Oedothorax gibbosus. This revealed a co-infection of at least three known (Wolbachia, Rickettsia and Cardinium) and the detection of a previously unreported endosymbiont bacterium (Rhabdochlamydia) in spiders. 16S rRNA gene sequences of Rhabdochlamydia matched closely with those of Candidatus R. porcellionis, which is currently only reported as a pathogen from a woodlouse and with Candidatus R. crassificans reported from a cockroach. Remarkably, this bacterium appears to present in very high proportions in one of the two populations only, with all investigated females being infected. We also recovered Acinetobacter in high abundance in one individual. In total, more than 99% of approximately 4.5M high-throughput sequencing reads were restricted to these five bacterial species. In contrast to previously reported screening studies of terrestrial arthropods, our results suggest that the bacterial communities in this spider species are dominated by, or even restricted to endosymbiont bacteria. Given the high prevalence of endosymbiont species in spiders, this bacterial community pattern could be widespread in the Araneae order.

  20. An LED-based UV-B irradiation system for tiny organisms: System description and demonstration experiment to determine the hatchability of eggs from four Tetranychus spider mite species from Okinawa.

    PubMed

    Suzuki, Takeshi; Yoshioka, Yoshio; Tsarsitalidou, Olga; Ntalia, Vivi; Ohno, Suguru; Ohyama, Katsumi; Kitashima, Yasuki; Gotoh, Tetsuo; Takeda, Makio; Koveos, Dimitris S

    2014-03-01

    We developed a computer-based system for controlling the photoperiod and irradiance of UV-B and white light from a 5×5 light-emitting diode (LED) matrix (100×100mm). In this system, the LED matrix was installed in each of four irradiation boxes and controlled by pulse-width modulators so that each box can independently emit UV-B and white light at irradiances of up to 1.5 and 4.0Wm(-2), respectively, or a combination of both light types. We used this system to examine the hatchabilities of the eggs of four Tetranychus spider mite species (T. urticae, T. kanzawai, T. piercei and T. okinawanus) collected from Okinawa Island under UV-B irradiation alone or simultaneous irradiation with white light for 12hd(-1) at 25°C. Although no eggs of any species hatched under the UV-B irradiation, even when the irradiance was as low as 0.02Wm(-2), the hatchabilities increased to >90% under simultaneous irradiation with 4.0Wm(-2) white light. At 0.06Wm(-2) UV-B, T. okinawanus eggs hatched (15% hatchability) under simultaneous irradiation with white light, whereas other species showed hatchabilities <1%. These results suggest that photolyases activated by white light may reduce UV-B-induced DNA damage in spider mite eggs and that the greater UV-B tolerance of T. okinawanus may explain its dominance on plants in seashore environments, which have a higher risk of exposure to reflected UV-B even on the undersurface of leaves. Our system will be useful for further examination of photophysiological responses of tiny organisms because of its ability to precisely control radiation conditions.

  1. Spider-mediated flux of PCBs from contaminated sediments to terrestrial ecosystems and potential risks to arachnivorous birds

    USGS Publications Warehouse

    Walters, D.M.; Mills, M.A.; Fritz, K.M.; Raikow, D.F.

    2010-01-01

    We investigated aquatic insect utilization and PCB exposure in riparian spiders at the Lake Hartwell Superfund site (Clemson, SC). We sampled sediments, adult chironomids, terrestrial insects, riparian spiders (Tetragnathidae, Araneidae, and Mecynogea lemniscata), and upland spiders (Araneidae) along a sediment contamination gradient. Stable isotopes (?13C, ? 15N) indicated that riparian spiders primarily consumed aquatic insects whereas upland spiders consumed terrestrial insects. PCBs in chironomids (mean 1240 ng/g among sites) were 2 orders of magnitude higher than terrestrial insects (15.2 ng/g), similar to differences between riparian (820?2012 ng/g) and upland spiders (30 ng/g). Riparian spider PCBs were positively correlated with sediment concentrations for all taxa (r2 = 0.44?0.87). We calculated spider-based wildlife values (WVs, the minimum spider PCB concentrations causing physiologically significant doses in consumers) to assess exposure risks for arachnivorous birds. Spider concentrations exceeded WVs for most birds at heavily contaminated sites and were ?14-fold higher for the most sensitive species (chickadee nestlings, Poecile spp.). Spiders are abundant and ubiquitous in riparian habitats, where they depend on aquatic insect prey. These traits, along with the high degree of spatial correlation between spider and sediment concentrations we observed, suggest that they are model indicator species for monitoring contaminated sediment sites and assessing risks associated with contaminant flux into terrestrial ecosystems. ?? This article not subject to U.S. Copyright. Published 2009 by the American Chemical Society.

  2. Protein families, natural history and biotechnological aspects of spider silk.

    PubMed

    Bittencourt, D; Oliveira, P F; Prosdocimi, F; Rech, E L

    2012-01-01

    Spiders are exceptionally diverse and abundant organisms in terrestrial ecosystems and their evolutionary success is certainly related to their capacity to produce different types of silks during their life cycle, making a specialized use on each of them. Presenting particularly tandemly arranged amino acid repeats, silk proteins (spidroins) have mechanical properties superior to most synthetic or natural high-performance fibers, which makes them very promising for biotechnology industry, with putative applications in the production of new biomaterials. During the evolution of spider species, complex behaviors of web production and usage have been coupled with anatomical specialization of spinning glands. Spiders retaining ancestral characters, such as the ones belonging to the Mygalomorph group, present simpler sorts of webs used mainly to build burrows and egg sacs, and their silks are produced by globular undifferentiated spinning glands. In contrast, Araneomorphae spiders have a complex spinning apparatus, presenting up to seven morphologically distinct glands, capable to produce a more complex set of silk polymers with different degrees of rigidness and elasticity associated with distinct behaviors. Aiming to provide a discussion involving a number of spider silks' biological aspects, in this review we present descriptions of members from each family of spidroin identified from five spider species of the Brazilian biodiversity, and an evolutionary study of them in correlation with the anatomical specialization of glands and spider's spinning behaviors. Due to the biotechnological importance of spider silks for the production of new biomaterials, we also discuss about the new possible technical and biomedical applications of spider silks and the current status of it. PMID:22911606

  3. Protein families, natural history and biotechnological aspects of spider silk.

    PubMed

    Bittencourt, D; Oliveira, P F; Prosdocimi, F; Rech, E L

    2012-01-01

    Spiders are exceptionally diverse and abundant organisms in terrestrial ecosystems and their evolutionary success is certainly related to their capacity to produce different types of silks during their life cycle, making a specialized use on each of them. Presenting particularly tandemly arranged amino acid repeats, silk proteins (spidroins) have mechanical properties superior to most synthetic or natural high-performance fibers, which makes them very promising for biotechnology industry, with putative applications in the production of new biomaterials. During the evolution of spider species, complex behaviors of web production and usage have been coupled with anatomical specialization of spinning glands. Spiders retaining ancestral characters, such as the ones belonging to the Mygalomorph group, present simpler sorts of webs used mainly to build burrows and egg sacs, and their silks are produced by globular undifferentiated spinning glands. In contrast, Araneomorphae spiders have a complex spinning apparatus, presenting up to seven morphologically distinct glands, capable to produce a more complex set of silk polymers with different degrees of rigidness and elasticity associated with distinct behaviors. Aiming to provide a discussion involving a number of spider silks' biological aspects, in this review we present descriptions of members from each family of spidroin identified from five spider species of the Brazilian biodiversity, and an evolutionary study of them in correlation with the anatomical specialization of glands and spider's spinning behaviors. Due to the biotechnological importance of spider silks for the production of new biomaterials, we also discuss about the new possible technical and biomedical applications of spider silks and the current status of it.

  4. Evolutionary morphology of the hemolymph vascular system of basal araneomorph spiders (Araneae: Araneomorphae).

    PubMed

    Huckstorf, Katarina; Michalik, Peter; Ramírez, Martín; Wirkner, Christian S

    2015-11-01

    The superfamily Austrochiloidea (Austrochilidae and Gradungulidae) take a pivotal position in araneomorph spider phylogeny. In this discussion crevice weaver spiders (Filistatidae) are of equal interest. Especially data from these phylogenetically uncertain yet basal off branching groups can enlighten our understanding on the evolution of organ systems. In the course of a survey on the evolutionary morphology of the circulatory system in spiders we therefore investigated the hemolymph vascular system in two austrochiloid and one filistatid species. Additionally some data on a hypochilid and a gradungulid species are included. Using up-to-date morphological methods, the vascular systems in these spiders are visualized three dimensionally. Ground pattern features of the circulatory systems in austrochiloid spiders are presented and the data discussed along recent lines of phylogenetic hypotheses. Special topics highlighted are the intraspecific variability of the origins of some prosomal arteries and the evolutionary correlation of respiratory and circulatory systems in spiders.

  5. Molecular Spiders in One Dimension

    PubMed Central

    Antal, Tibor; Krapivsky, P. L.; Mallick, Kirone

    2008-01-01

    Molecular spiders are synthetic bio-molecular systems which have “legs” made of short single-stranded segments of DNA. Spiders move on a surface covered with single-stranded DNA segments complementary to legs. Different mappings are established between various models of spiders and simple exclusion processes. For spiders with simple gait and varying number of legs we compute the diffusion coefficient; when the hopping is biased we also compute their velocity. PMID:19079565

  6. [Effects of Solenopsis invicta invasion on the diversity of spider communities in a corn field].

    PubMed

    Jun, Huang; Yi-Juan, Xu; Yong-Yue, Lu; Ling, Zeng

    2012-04-01

    By using pitfall trapping and ocular estimation, this paper studied the effects of Solenopsis invicta invasion on the diversity of spider communities in a corn field. A total of 16 spider species belonging to 8 families were recorded. In the plot S. invicta invaded, there were 10 spider species of 6 families, among which, 5 species of 4 families were in pesticide-treated plot, and 11 species of 8 families were in control plot. The spiders were dominated by wandering species, mainly belonging to the families Salticidae and Oxyopidae, and the dominant species were Oxyopex sertatus, Myrmarachne joblotii, and Myrmarachne sp. In the plot S. invicta invaded, the population quantity of S. invicta began to increase steadily from the late whorl stage of corn, with the peak (225 individuals) through the earring stage, but decreased steadily thereafter, with the decrement of the spiders of genus Oxyopex reached 79.2%, while the population quantity of the spiders of genus Myrmarachne had no significant change. With the growth of corn, the species number, diversity index, and evenness index of the spiders in S. invicta-invaded and pesticide-treated plot decreased and the predominant indices increased gradually, while the situation in control plot was in adverse. It was concluded that due to the S. invicta invasion in corn field, the community structure of spiders changed.

  7. Cuticular antifungals in spiders: density- and condition dependence.

    PubMed

    González-Tokman, Daniel; Ruch, Jasmin; Pulpitel, Tamara; Ponton, Fleur

    2014-01-01

    Animals living in groups face a high risk of disease contagion. In many arthropod species, cuticular antimicrobials constitute the first protective barrier that prevents infections. Here we report that group-living spiders produce cuticular chemicals which inhibit fungal growth. Given that cuticular antifungals may be costly to produce, we explored whether they can be modulated according to the risk of contagion (i.e. under high densities). For this purpose, we quantified cuticular antifungal activity in the subsocial crab spider Diaea ergandros in both natural nests and experimentally manipulated nests of varying density. We quantified the body-condition of spiders to test whether antifungal activity is condition dependent, as well as the effect of spider density on body-condition. We predicted cuticular antifungal activity to increase and body-condition to decrease with high spider densities, and that antifungal activity would be inversely related to body-condition. Contrary to our predictions, antifungal activity was neither density- nor condition-dependent. However, body-condition decreased with density in natural nests, but increased in experimental nests. We suggest that pathogen pressure is so important in nature that it maintains high levels of cuticular antifungal activity in spiders, impacting negatively on individual energetic condition. Future studies should identify the chemical structure of the isolated antifungal compounds in order to understand the physiological basis of a trade-off between disease prevention and energetic condition caused by group living, and its consequences in the evolution of sociality in spiders.

  8. Cuticular Antifungals in Spiders: Density- and Condition Dependence

    PubMed Central

    González-Tokman, Daniel; Ruch, Jasmin; Pulpitel, Tamara; Ponton, Fleur

    2014-01-01

    Animals living in groups face a high risk of disease contagion. In many arthropod species, cuticular antimicrobials constitute the first protective barrier that prevents infections. Here we report that group-living spiders produce cuticular chemicals which inhibit fungal growth. Given that cuticular antifungals may be costly to produce, we explored whether they can be modulated according to the risk of contagion (i.e. under high densities). For this purpose, we quantified cuticular antifungal activity in the subsocial crab spider Diaea ergandros in both natural nests and experimentally manipulated nests of varying density. We quantified the body-condition of spiders to test whether antifungal activity is condition dependent, as well as the effect of spider density on body-condition. We predicted cuticular antifungal activity to increase and body-condition to decrease with high spider densities, and that antifungal activity would be inversely related to body-condition. Contrary to our predictions, antifungal activity was neither density- nor condition-dependent. However, body-condition decreased with density in natural nests, but increased in experimental nests. We suggest that pathogen pressure is so important in nature that it maintains high levels of cuticular antifungal activity in spiders, impacting negatively on individual energetic condition. Future studies should identify the chemical structure of the isolated antifungal compounds in order to understand the physiological basis of a trade-off between disease prevention and energetic condition caused by group living, and its consequences in the evolution of sociality in spiders. PMID:24637563

  9. Structural and optical studies on selected web spinning spider silks.

    PubMed

    Karthikeyani, R; Divya, A; Mathavan, T; Asath, R Mohamed; Benial, A Milton Franklin; Muthuchelian, K

    2017-01-01

    This study investigates the structural and optical properties in the cribellate silk of the sheet web spider Stegodyphus sarasinorum Karsch (Eresidae) and the combined dragline, viscid silk of the orb-web spiders Argiope pulchella Thorell (Araneidae) and Nephila pilipes Fabricius (Nephilidae). X-ray diffraction (XRD), Fourier transform infra-red (FTIR), Ultraviolet-visible (UV-Vis) and fluorescence spectroscopic techniques were used to study these three spider silk species. X-ray diffraction data are consistent with the amorphous polymer network which is arising from the interaction of larger side chain amino acid contributions due to the poly-glycine rich sequences known to be present in the proteins of cribellate silk. The same amorphous polymer networks have been determined from the combined dragline and viscid silk of orb-web spiders. From FTIR spectra the results demonstrate that, cribellate silk of Stegodyphus sarasinorum, combined dragline viscid silk of Argiope pulchella and Nephila pilipes spider silks are showing protein peaks in the amide I, II and III regions. Further they proved that the functional groups present in the protein moieties are attributed to α-helical and side chain amino acid contributions. The optical properties of the obtained spider silks such as extinction coefficients, refractive index, real and imaginary dielectric constants and optical conductance were studied extensively from UV-Vis analysis. The important fluorescent amino acid tyrosine is present in the protein folding was investigated by using fluorescence spectroscopy. This research would explore the protein moieties present in the spider silks which were found to be associated with α-helix and side chain amino acid contributions than with β-sheet secondary structure and also the optical relationship between the three different spider silks are investigated. Successful spectroscopic knowledge of the internal protein structure and optical properties of the spider silks could

  10. Structural and optical studies on selected web spinning spider silks.

    PubMed

    Karthikeyani, R; Divya, A; Mathavan, T; Asath, R Mohamed; Benial, A Milton Franklin; Muthuchelian, K

    2017-01-01

    This study investigates the structural and optical properties in the cribellate silk of the sheet web spider Stegodyphus sarasinorum Karsch (Eresidae) and the combined dragline, viscid silk of the orb-web spiders Argiope pulchella Thorell (Araneidae) and Nephila pilipes Fabricius (Nephilidae). X-ray diffraction (XRD), Fourier transform infra-red (FTIR), Ultraviolet-visible (UV-Vis) and fluorescence spectroscopic techniques were used to study these three spider silk species. X-ray diffraction data are consistent with the amorphous polymer network which is arising from the interaction of larger side chain amino acid contributions due to the poly-glycine rich sequences known to be present in the proteins of cribellate silk. The same amorphous polymer networks have been determined from the combined dragline and viscid silk of orb-web spiders. From FTIR spectra the results demonstrate that, cribellate silk of Stegodyphus sarasinorum, combined dragline viscid silk of Argiope pulchella and Nephila pilipes spider silks are showing protein peaks in the amide I, II and III regions. Further they proved that the functional groups present in the protein moieties are attributed to α-helical and side chain amino acid contributions. The optical properties of the obtained spider silks such as extinction coefficients, refractive index, real and imaginary dielectric constants and optical conductance were studied extensively from UV-Vis analysis. The important fluorescent amino acid tyrosine is present in the protein folding was investigated by using fluorescence spectroscopy. This research would explore the protein moieties present in the spider silks which were found to be associated with α-helix and side chain amino acid contributions than with β-sheet secondary structure and also the optical relationship between the three different spider silks are investigated. Successful spectroscopic knowledge of the internal protein structure and optical properties of the spider silks could

  11. Effects of natural forest fragmentation on a Hawaiian spider community

    USGS Publications Warehouse

    Vandergast, Amy; Gillespie, Rosemary G.

    2004-01-01

    The kipuka system, a network of forest fragments surrounded by lava flows on the island of Hawaii, offers an opportunity to study the natural, long-term fragmentation of a native ecosystem. We examined the impacts of habitat edges upon the community structure of nocturnally active native spiders, primarily in the genus Tetragnatha. We measured plant and spider species distributions across the edges of four small fragments and one large continuously forested area that were surrounded by a lava flow in 1855. Results indicated that an ???20 m edge ecotone surrounds core forest habitat. Spider community structure changed across the edge, with a decrease in total species richness and diversity at the forest/lava boundary, and a change in the dominant taxon from native Tetragnatha (Tetragnathidae) to native Cyclosa (Araneidae). Severe habitat restrictions were found for some spider species. In addition, nearly all of the spiders captured were endemic species, and the few introduced species were limited to the younger and more open lava flows. Our results suggest that species responses to edges can vary, and that core habitat specialists may decline in fragmented conditions.

  12. Spider diversity in coffee agroecosystems: the influence of agricultural intensification and aggressive ants.

    PubMed

    Marín, Linda; Perfecto, Ivette

    2013-04-01

    Spiders are a very diverse group of invertebrate predators found in agroecosystems and natural systems. However, spider distribution, abundance, and eventually their ecological function in ecosystems can be influenced by abiotic and biotic factors such as agricultural intensification and dominant ants. Here we explore the influence of both agricultural intensification and the dominant arboreal ant Azteca instabilis on the spider community in coffee agroecosystems in southern Mexico. To measure the influence of the arboreal ant Azteca instabilis (F. Smith) on the spider community inhabiting the coffee layer of coffee agroecosystems, spiders were collected from coffee plants that were and were not patrolled by the ant in sites differing in agricultural intensification. For 2008, generalized linear mixed models showed that spider diversity was affected positively by agricultural intensification but not by the ant. However, results suggested that some spider species were associated with A. instabilis. Therefore, in 2009 we concentrated our research on the effect of A. instabilis on spider diversity and composition. For 2009, generalized linear mixed models show that spider richness and abundance per plant were significantly higher in the presence of A. instabilis. In addition, analyses of visual counts of insects and sticky traps data show that more resources were present in plants patrolled by the ant. The positive effect of A. instabilis on spiders seems to be caused by at least two mechanisms: high abundance of insects and protection against predators.

  13. Relationship between colouration and body condition in a crab spider that lures pollinators.

    PubMed

    Gawryszewski, Felipe M; Llandres, Ana L; Herberstein, Marie E

    2012-04-01

    Sit-and-wait predators have evolved several traits that increase the probability of encountering prey, including lures that attract prey. Although most crab spiders (Thomisidae) are known by their ability to change colour in order to match the background, a few use a different strategy. They are UV-reflective, creating a colour contrast against UV-absorbing flowers that is attractive for pollinators. The nature of the relationship between colour contrast and foraging success is unknown, as is how spiders trade off the potential costs and benefits of strong colour contrast. Therefore, this study investigated the relationship between spider colouration, foraging success and background colouration in a crab spider species known to lure pollinators via UV reflectance (Thomisus spectabilis). Field data revealed that spider body condition - a proxy of past foraging success - is positively related to overall colour contrast. We experimentally tested the effect of satiation and background colour on spider colour change. Throughout the experiment, spiders changed their colour contrast regardless of their food intake, suggesting that colour contrast and the UV component contributing to overall contrast are not caused by spider condition. Although spiders responded to different backgrounds by subtly changing their body colour, this did not result in colour matching. We believe that the observed variation in colour contrast and hence conspicuousness in the field, coupled with the spiders' reaction to our manipulation, could be the result of plasticity in response to prey.

  14. Bromeliad-living spiders improve host plant nutrition and growth.

    PubMed

    Romero, Gustavo Q; Mazzafera, Paulo; Vasconcellos-Neto, Joao; Trivelin, Paulo C O

    2006-04-01

    Although bromeliads are believed to obtain nutrients from debris deposited by animals in their rosettes, there is little evidence to support this assumption. Using stable isotope methods, we found that the Neotropical jumping spider Psecas chapoda (Salticidae), which lives strictly associated with the terrestrial bromeliad Bromelia balansae, contributed 18% of the total nitrogen of its host plant in a greenhouse experiment. In a one-year field experiment, plants with spiders produced leaves 15% longer than plants from which the spiders were excluded. This is the first study to show nutrient provisioning in a spider-plant system. Because several animal species live strictly associated with bromeliad rosettes, this type of facultative mutualism involving the Bromeliaceae may be more common than previously thought.

  15. Untangling the spider's web.

    PubMed

    Vollrath, F

    1988-12-01

    The spider's orb web provides an excellent opportunity to study the decision rules of a highly complex orientation behaviour. The behaviour is inherited, and it has evolved from laying a single line to configuring the geometrical thread pattern of the orb. The possibility that the algorithms of orb web construction may have evolved convergently adds to the excitement of the experimental analysis. Analytical studies modelling the spider's rules of thread configuration might penetrate where descriptive studies of web design or construction behaviour perforce stop short. PMID:21227285

  16. Spider Transcriptomes Identify Ancient Large-Scale Gene Duplication Event Potentially Important in Silk Gland Evolution

    PubMed Central

    Clarke, Thomas H.; Garb, Jessica E.; Hayashi, Cheryl Y.; Arensburger, Peter; Ayoub, Nadia A.

    2015-01-01

    The evolution of specialized tissues with novel functions, such as the silk synthesizing glands in spiders, is likely an influential driver of adaptive success. Large-scale gene duplication events and subsequent paralog divergence are thought to be required for generating evolutionary novelty. Such an event has been proposed for spiders, but not tested. We de novo assembled transcriptomes from three cobweb weaving spider species. Based on phylogenetic analyses of gene families with representatives from each of the three species, we found numerous duplication events indicative of a whole genome or segmental duplication. We estimated the age of the gene duplications relative to several speciation events within spiders and arachnids and found that the duplications likely occurred after the divergence of scorpions (order Scorpionida) and spiders (order Araneae), but before the divergence of the spider suborders Mygalomorphae and Araneomorphae, near the evolutionary origin of spider silk glands. Transcripts that are expressed exclusively or primarily within black widow silk glands are more likely to have a paralog descended from the ancient duplication event and have elevated amino acid replacement rates compared with other transcripts. Thus, an ancient large-scale gene duplication event within the spider lineage was likely an important source of molecular novelty during the evolution of silk gland-specific expression. This duplication event may have provided genetic material for subsequent silk gland diversification in the true spiders (Araneomorphae). PMID:26058392

  17. Spider Transcriptomes Identify Ancient Large-Scale Gene Duplication Event Potentially Important in Silk Gland Evolution.

    PubMed

    Clarke, Thomas H; Garb, Jessica E; Hayashi, Cheryl Y; Arensburger, Peter; Ayoub, Nadia A

    2015-06-08

    The evolution of specialized tissues with novel functions, such as the silk synthesizing glands in spiders, is likely an influential driver of adaptive success. Large-scale gene duplication events and subsequent paralog divergence are thought to be required for generating evolutionary novelty. Such an event has been proposed for spiders, but not tested. We de novo assembled transcriptomes from three cobweb weaving spider species. Based on phylogenetic analyses of gene families with representatives from each of the three species, we found numerous duplication events indicative of a whole genome or segmental duplication. We estimated the age of the gene duplications relative to several speciation events within spiders and arachnids and found that the duplications likely occurred after the divergence of scorpions (order Scorpionida) and spiders (order Araneae), but before the divergence of the spider suborders Mygalomorphae and Araneomorphae, near the evolutionary origin of spider silk glands. Transcripts that are expressed exclusively or primarily within black widow silk glands are more likely to have a paralog descended from the ancient duplication event and have elevated amino acid replacement rates compared with other transcripts. Thus, an ancient large-scale gene duplication event within the spider lineage was likely an important source of molecular novelty during the evolution of silk gland-specific expression. This duplication event may have provided genetic material for subsequent silk gland diversification in the true spiders (Araneomorphae).

  18. The Spider Files

    ERIC Educational Resources Information Center

    McDonald, James; Dominguez, Lynn

    2012-01-01

    As children develop misconceptions about animals they believe are dangerous, they also adopt attitudes that are difficult to change. Changing these attitudes is challenging for teachers. One animal that is easy to find but difficult for children to understand is a spider. As with most wild animals, they are difficult to teach about because…

  19. Spider Web Pattern

    NASA Technical Reports Server (NTRS)

    2006-01-01

    A delicate pattern, like that of a spider web, appears on top of the Mars residual polar cap, after the seasonal carbon-dioxide ice slab has disappeared. Next spring, these will likely mark the sites of vents when the carbon-dioxide ice cap returns. This Mars Global Surveyor, Mars Orbiter Camera image is about 3-kilometers wide (2-miles).

  20. The molecular structures of major ampullate silk proteins of the wasp spider, Argiope bruennichi: a second blueprint for synthesizing de novo silk.

    PubMed

    Zhang, Yang; Zhao, Ai-Chun; Sima, Yang-Hu; Lu, Cheng; Xiang, Zhong-Huai; Nakagaki, Masao

    2013-03-01

    The dragline silk of orb-weaving spiders possesses extremely high tensile strength and elasticity. To date, full-length sequences of only two genes encoding major ampullate silk protein (MaSp) in Latrodectus hesperus have been determined. In order to further understand this gene family, we utilized in this study a variety of strategies to isolate full-length MaSp1 and MaSp2 cDNAs in the wasp spider Argiope bruennichi. A. bruennichi MaSp1 and MaSp2 are primarily composed of remarkably homogeneous ensemble repeats containing several complex motifs, and both have highly conserved C-termini and N-termini. Two novel amino acid motifs, GGF and SGR, were found in MaSp1 and MaSp2, respectively. Amino acid composition analysis of silk, luminal contents and predicted sequences indicates that MaSp1 and MaSp2 are two major components of major ampullate glands and that the ratio of MaSp1 to MaSp2 is approximately 3:2 in dragline silk. Furthermore, both the MaSp1:MaSp2 ratio and the conserved termini are closely linked with the production of high quality synthetic fibers. Our results make an important contribution to our understanding of major ampullate silk protein structure and provide a second blueprint for creating new composite silk which mimics natural spider dragline silk. PMID:23262065

  1. Direct solvation of glycoproteins by salts in spider silk glues enhances adhesion and helps to explain the evolution of modern spider orb webs.

    PubMed

    Sahni, Vasav; Miyoshi, Toshikazu; Chen, Kelley; Jain, Dharamdeep; Blamires, Sean J; Blackledge, Todd A; Dhinojwala, Ali

    2014-04-14

    The evolutionary origin of modern viscid silk orb webs from ancient cribellate silk ancestors is associated with a 95% increase in diversity of orb-weaving spiders, and their dominance as predators of flying insects, yet the transition's mechanistic basis is an evolutionary puzzle. Ancient cribellate silk is a dry adhesive that functions through van der Waals interactions. Viscid threads adhere more effectively than cribellate threads because of the high extensibility of their axial silk fibers, recruitment of multiple glue droplets, and firm adhesion of the viscid glue droplets. Viscid silk's extensibility is permitted by the glue's high water content, so that organic and inorganic salts present in viscid glue droplets play an essential role in contributing to adhesion by sequestering the atmospheric water that plasticizes the axial silk fibers. Here, we provide direct molecular and macro-scale evidence to show that salts also cause adhesion by directly solvating the glycoproteins, regardless of water content, thus imparting viscoelasticity and allowing the glue droplets to establish good contact. This "dual role" of salts, plasticizing the axial silk indirectly through water sequestration and directly solvating the glycoproteins, provides a crucial link to the evolutionary transition from cribellate silk to viscid silk. In addition, salts also provide a simple mechanism for adhering even at the extremes of relative humidity, a feat eluding most synthetic adhesives. PMID:24588057

  2. Brown spider envenomation.

    PubMed

    Peterson, Michael E

    2006-11-01

    The venom from spiders of the genus Loxosceles, the most famous being Loxosceles recluse (the most brown recluse spider) can cause serious poisoning. These spiders inhabit the south and south central states from Georgia through Texas and north to southern Wisconsin. They are commonly called violin spiders because of the violin-shaped marking on the dorsum of the cephalothorax. Many dermonecrotic lesions are incorrectly diagnosed as Brown recluse bites, as up to 50% of the diagnoses are in geographic regions of the country which do not have Loxosceles spiders. Sphingomyelinase D is the primary venom dermonecrotic factor. The toxin depletes serum hemolytic complement, prolongs the activated partial thromboplastin time and depletes clotting factors VIII, IX, XI, and XII. The venom induces rapid coagulation and occlusion of small capillaries, causing subsequent tissue necrosis. A classic "bulls eye" lesion develops, an erythematous area inside of which is a pale ischemic region that develops a dark necrotic center as the lesion matures. Healing is slow, and these ulcers may persist for months leaving a deep scar. Systemic signs occur less commonly but can be life threatening. The most prevalent sign is a hemolytic anemia with significant hemoglobinuria. There is no specific antidote. Dapsone a leukocyte inhibitor has been shown to be effective in treating dermal lesions in animal models. Conservative therapy includes several cleanings daily with Burrow's solution and hydrogen peroxide. Systemic signs of Loxosceles envenomation are potentially fatal and should be aggressively addressed. Hospitalization and intravenous fluid therapy may be needed to maintain adequate hydration and to protect renal function.

  3. Impacts of spinosad and λ-cyhalothrin on spider communities in cabbage fields in south Texas.

    PubMed

    Liu, T-X; Irungu, R W; Dean, D A; Harris, M K

    2013-04-01

    Spiders are a principal arthropod group that preys on numerous pests of vegetables and other crops. In this study, we determined the effects of the two most commonly used insecticides, spinosad and λ-cyhalothrin, on diversity of spiders on cabbage in south Texas. In two seasons (fall 2008 and spring 2009), we collected a total of 588 spiders belonging to 53 species in 11 families from spinosad and λ-cyhalothrin-treated cabbages and the untreated control plants. A great majority of spiders were collected from the pitfall traps (554) where only a few (34) were collected from the blower/vacuum sampling. In the insecticide-treated plots, there were significantly fewer spider individuals, species and families than in untreated fields. Spinosad had significantly less effect on spiders in total individuals, number of species and families than λ-cyhalothrin. The effects of the two insecticides were further demonstrated by the Shannon-Weiner index (H') and the hierarchical richness index (HRI). Spider diversity in the spinosad-treated plots were not significantly different from that in the untreated fields but were greater than those in λ-cyhalothrin-treated plots in both seasons when measured by H' values. In contrast, the H' values of spider's diversity in the λ-cyhalothrin-treated plots were significantly lower than spinosad-treated and untreated plots. High values of HRI for spider richness in the spinosad-treated plots suggested that spinosad had less effect on spiders than λ-cyhalothrin. We concluded that spinosad was more compatible with spiders on cabbage compared to λ-cyhalothrin and that this information should be used when developing insecticide resistance management strategies.

  4. Transmission X-ray microscopy of spider dragline silk.

    PubMed

    Glisović, Anja; Thieme, Jürgen; Guttmann, Peter; Salditt, Tim

    2007-01-30

    We have investigated the structure of spider silk fibers from two different Nephila species and three different Araneus species by transmission X-ray microscopy (TXM). Single fibers and double fibers have been imaged. All images are in agreement with a homogenous density on length scales between the fiber diameter and the resolution of the instrument, which is about 25 nm. PMID:16889826

  5. Spiders associated with papaya, Carica papaya L., in Puerto Rico

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The main objective of this work was to study the species composition and population dynamics of spiders associated with papaya plantings in three papaya production areas: Corozal, Isabela, and Lajas, Puerto Rico. Nineteen species representing seven families and 15 genera were identified. Members of ...

  6. Untangling the web...spiders in Arizona fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many kinds of arthropod natural enemies (predators and parasitoids) inhabit crop fields in Arizona and can have a large negative impact on several pest insect species that also infest these crops. Many different species of spiders are common in cotton, alfalfa and other crops in Arizona. Among the ...

  7. Mysmenidae, a spider family newly recorded from Tibet (Arachnida, Araneae)

    PubMed Central

    Lin, Yucheng; Li, Shuqiang

    2016-01-01

    Abstract The spider family Mysmenidae is reported from Tibet for the first time. Two new species, Chanea voluta sp. n. (male and female) and Mysmena lulanga sp. n. (male and female) are found in eastern Tibet in high altitude. Morphological descriptions, diagnoses and comparative photos are provided for the two new species. PMID:26843831

  8. Detection and phylogenetic analysis of bacteriophage WO in spiders (Araneae).

    PubMed

    Yan, Qian; Qiao, Huping; Gao, Jin; Yun, Yueli; Liu, Fengxiang; Peng, Yu

    2015-11-01

    Phage WO is a bacteriophage found in Wolbachia. Herein, we represent the first phylogenetic study of WOs that infect spiders (Araneae). Seven species of spiders (Araneus alternidens, Nephila clavata, Hylyphantes graminicola, Prosoponoides sinensis, Pholcus crypticolens, Coleosoma octomaculatum, and Nurscia albofasciata) from six families were infected by Wolbachia and WO, followed by comprehensive sequence analysis. Interestingly, WO could be only detected Wolbachia-infected spiders. The relative infection rates of those seven species of spiders were 75, 100, 88.9, 100, 62.5, 72.7, and 100 %, respectively. Our results indicated that both Wolbachia and WO were found in three different body parts of N. clavata, and WO could be passed to the next generation of H. graminicola by vertical transmission. There were three different sequences for WO infected in A. alternidens and two different WO sequences from C. octomaculatum. Only one sequence of WO was found for the other five species of spiders. The discovered sequence of WO ranged from 239 to 311 bp. Phylogenetic tree was generated using maximum likelihood (ML) based on the orf7 gene sequences. According to the phylogenetic tree, WOs in N. clavata and H. graminicola were clustered in the same group. WOs from A. alternidens (WAlt1) and C. octomaculatum (WOct2) were closely related to another clade, whereas WO in P. sinensis was classified as a sole cluster.

  9. Spider-Venom Peptides as Bioinsecticides

    PubMed Central

    Windley, Monique J.; Herzig, Volker; Dziemborowicz, Sławomir A.; Hardy, Margaret C.; King, Glenn F.; Nicholson, Graham M.

    2012-01-01

    Over 10,000 arthropod species are currently considered to be pest organisms. They are estimated to contribute to the destruction of ~14% of the world’s annual crop production and transmit many pathogens. Presently, arthropod pests of agricultural and health significance are controlled predominantly through the use of chemical insecticides. Unfortunately, the widespread use of these agrochemicals has resulted in genetic selection pressure that has led to the development of insecticide-resistant arthropods, as well as concerns over human health and the environment. Bioinsecticides represent a new generation of insecticides that utilise organisms or their derivatives (e.g., transgenic plants, recombinant baculoviruses, toxin-fusion proteins and peptidomimetics) and show promise as environmentally-friendly alternatives to conventional agrochemicals. Spider-venom peptides are now being investigated as potential sources of bioinsecticides. With an estimated 100,000 species, spiders are one of the most successful arthropod predators. Their venom has proven to be a rich source of hyperstable insecticidal mini-proteins that cause insect paralysis or lethality through the modulation of ion channels, receptors and enzymes. Many newly characterized insecticidal spider toxins target novel sites in insects. Here we review the structure and pharmacology of these toxins and discuss the potential of this vast peptide library for the discovery of novel bioinsecticides. PMID:22741062

  10. Evolution of stenophagy in spiders (Araneae): evidence based on the comparative analysis of spider diets.

    PubMed

    Pekár, Stano; Coddington, Jonathan A; Blackledge, Todd A

    2012-03-01

    Stenophagy (narrow diet breadth) represents an extreme of trophic specialization in carnivores, but little is known about the forces driving its evolution. We used spiders, the most diversified group of terrestrial predators, to investigate whether stenophagy (1) promoted diversification; (2) was phylogenetically conserved and evolutionarily derived state; and (3) was determined either by geographical distribution and foraging guild. We used published data on the prey of almost 600 species. Six categories of stenophagy were found: myrmecophagy, araneophagy, lepidopterophagy, termitophagy, dipterophagy, and crustaceophagy. We found that the species diversity of euryphagous genera and families was similar to stenophagous genera and families. At the family level, stenophagy evolved repeatedly and independently. Within families, the basal condition was oligophagy or euryphagy. Most types of stenophagy were clearly derived: myrmecophagy in Zodariidae; lepidopterophagy in Araneidae; dipterophagy in Theridiidae. In contrast, araneophagy was confined to basal and intermediate lineages, suggesting its ancestral condition. The diet breadth of species from the tropics and subtropics was less diverse than species from the temperate zone. Diet breadth was lower in cursorial spiders compared to web-building species. Thus, the evolution of stenophagy in spiders appears to be complex and governed by phylogeny as well as by ecological determinants.

  11. Comparative analysis of passive defences in spiders (Araneae).

    PubMed

    Pekár, Stano

    2014-07-01

    Being frequent prey of many predators, including especially wasps and birds, spiders have evolved a variety of defence mechanisms. Here I studied patterns of passive defences, namely anachoresis, crypsis, masquerade, aposematism and Batesian mimicry, in spiders. Using published information pertaining more than 1000 spider species, the phylogenetic pattern of different passive defences (i.e. defences that decrease the risk of an encounter with the predator) was investigated. Furthermore, I studied the effect of foraging guild, geographical distribution and diel activity on the frequency of defences as these determine the predators diversity, presence and perception. I found that crypsis (background matching) combined with anachoresis (hiding) was the most frequent defence confined mainly to families/genera at the base of the tree. Aposematism (warning coloration) and Batesian mimicry (imitation of noxious/dangerous model) were found in taxa that branched later in the tree, and masquerade (imitation of inedible objects) was confined to families at intermediate positions of the tree. Aposematism and Batesian mimicry were restricted to a few lineages. Masquerade was used particularly by web-building species with nocturnal activity. Aposematism was rare but mainly used by web-building diurnal species. Batesian mimicry was frequently observed in cursorial species with diurnal activity. Cryptic species were more common in temperate zones, whereas aposematic and mimetic species were more common in the tropics. Here I show that the evolution of passive defences in spiders was influenced by the ecology of species. Then, I discuss the evolutionary significance of the particularly defences.

  12. Influence of spider silk on refugia preferences of the recluse spiders Loxosceles reclusa and Loxosceles laeta (Araneae: Sicariidae).

    PubMed

    Vetter, Richard S; Rust, Michael K

    2010-06-01

    In a previous experimental study, recluse spiders Loxosceles reclusa Gertsch and Mulaik and Loxosceles laeta (Nicolet) (Araneae: Sicariidae) preferred small cardboard refugia covered with conspecific silk compared with never-occupied refugia. Herein, we investigated some factors that might be responsible for this preference using similar cardboard refugia. When the two Loxosceles species were given choices between refugia previously occupied by their own and by the congeneric species, neither showed a species-specific preference; however, each chose refugia coated with conspecific silk rather than those previously inhabited by a distantly related cribellate spider, Metaltella simoni (Keyserling). When L. laeta spiders were offered refugia that were freshly removed from silk donors compared with heated, aged refugia from the same silk donor, older refugia were preferred. Solvent extracts of L. laeta silk were chosen approximately as often as control refugia when a range of solvents (methylene chloride:methanol, water, and hexane) were used. However, when acetone was used on similar silk, there was a statistical preference for the control, indicating that there might be a mildly repellent aspect to acetone-washed silk. Considering the inability to show attraction to chemical aspects of fresh silk, it seems that physical attributes may be more important for selection and that there might be repellency to silk of a recently vacated spider. These findings are discussed in regard to pest management strategies to control recluse spiders.

  13. Pathways to spider phobia.

    PubMed

    Merckelbach, H; Arntz, A; Arrindell, W A; de Jong, P J

    1992-09-01

    Using a revised version of the Phobic Origin Questionnaire (POQ; Ost, L. G. & Hugdahl, K. Behaviour Research and Therapy, 19, 439-477; 1981), the present study examined whether conditioning experiences, modeling experiences, and/or informational learning experiences were more often reported by spider phobics (n = 41) than by non-fearful controls (n = 30). The two groups did not differ with regard to the overall frequency of conditioning or modeling events. Remarkably, the frequency of informational learning was higher among non-fearful Ss than among phobics. Although the limitations inherent to the retrospective nature of the present study should be borne in mind, the data suggest that, at least in spider phobics, conditioning events, modeling experiences, and/or informational learning do not necessarily give rise to phobic fears.

  14. Nukuhiva Berland, 1935 is a troglobitic wolf spider (Araneae: Lycosidae), not a nursery-web spider (Pisauridae).

    PubMed

    Framenau, Volker W; Lehtinen, Pekka T

    2015-10-07

    The monotypic genus Nukuhiva Berland, 1935 with N. adamsoni (Berland, 1933) as type species, is re-described and transferred from the Pisauridae Simon, 1890 (fishing or nursery-web spiders) to the Lycosidae Sundevall, 1833 (wolf spiders) based on genitalic and somatic characters. Nukuhiva adamsoni, originally described from French Polynesia, appears to inhabit mountainous habitats of volcanic origin. Its troglobitic morphology--comparatively small eyes and pale, uniform coloration--suggest it to be associated with subterranean habitats such as caves or lava tubes, similar to the Hawaiian troglobitic species Lycosa howarthi Gertsch, 1973 and Adelocosa anops Gertsch, 1973.

  15. Jerzego, a new hisponine jumping spider from Borneo (Araneae: Salticidae).

    PubMed

    Maddison, Wayne P; Piascik, Edyta K

    2014-01-01

    A new genus and species of hisponine jumping spider from Sarawak, Jerzego corticicola Maddison sp. nov. are described, representing one of the few hisponine jumping spiders known from Asia, and the only whose male is known. Although similar to the primarily-Madagascan genus Hispo in having an elongate and flat body, sequences of 28s and 16sND1 genes indicate that Jerzego is most closely related to Massagris and Tomomingi, a result consistent with morphology. Females of Jerzego and other genera of Hisponinae were found to have an unusual double copulatory duct, which appears to be a synapomorphy of the subfamily. Two species are transferred from Hispo, Jerzego bipartitus (Simon) comb. nov. and Jerzego alboguttatus (Simon) comb. nov. Diagnostic illustrations and photographs of living spiders are provided.  PMID:25284419

  16. Factors that influence the beta-diversity of spider communities in northwestern Argentinean Grasslands.

    PubMed

    Rodriguez-Artigas, Sandra M; Ballester, Rodrigo; Corronca, Jose A

    2016-01-01

    Beta-diversity, defined as spatial replacement in species composition, is crucial to the understanding of how local communities assemble. These changes can be driven by environmental or geographic factors (such as geographic distance), or a combination of the two. Spiders have been shown to be good indicators of environmental quality. Accordingly, spiders are used in this work as model taxa to establish whether there is a decrease in community similarity that corresponds to geographic distance in the grasslands of the Campos & Malezales ecoregion (Corrientes). Furthermore, the influence of climactic factors and local vegetation heterogeneity (environmental factors) on assemblage composition was evaluated. Finally, this study evaluated whether the differential dispersal capacity of spider families is a factor that influences their community structure at a regional scale. Spiders were collected with a G-Vac from vegetation in six grassland sites in the Campos & Malezales ecoregion that were separated by a minimum of 13 km. With this data, the impact of alpha-diversity and different environmental variables on the beta-diversity of spider communities was analysed. Likewise, the importance of species replacement and nesting on beta-diversity and their contribution to the regional diversity of spider families with different dispersion capacities was evaluated. The regional and site-specific inventories obtained were complete. The similarity between spider communities declined as the geographic distance between sites increased. Environmental variables also influenced community composition; stochastic events and abiotic forces were the principal intervening factors in assembly structure. The differential dispersal capacity of spider groups also influenced community structure at a regional scale. The regional beta-diversity, as well as species replacement, was greater in high and intermediate vagility spiders; while nesting was greater in spiders with low dispersion

  17. Factors that influence the beta-diversity of spider communities in northwestern Argentinean Grasslands

    PubMed Central

    Rodriguez-Artigas, Sandra M.; Ballester, Rodrigo

    2016-01-01

    Beta-diversity, defined as spatial replacement in species composition, is crucial to the understanding of how local communities assemble. These changes can be driven by environmental or geographic factors (such as geographic distance), or a combination of the two. Spiders have been shown to be good indicators of environmental quality. Accordingly, spiders are used in this work as model taxa to establish whether there is a decrease in community similarity that corresponds to geographic distance in the grasslands of the Campos & Malezales ecoregion (Corrientes). Furthermore, the influence of climactic factors and local vegetation heterogeneity (environmental factors) on assemblage composition was evaluated. Finally, this study evaluated whether the differential dispersal capacity of spider families is a factor that influences their community structure at a regional scale. Spiders were collected with a G-Vac from vegetation in six grassland sites in the Campos & Malezales ecoregion that were separated by a minimum of 13 km. With this data, the impact of alpha-diversity and different environmental variables on the beta-diversity of spider communities was analysed. Likewise, the importance of species replacement and nesting on beta-diversity and their contribution to the regional diversity of spider families with different dispersion capacities was evaluated. The regional and site-specific inventories obtained were complete. The similarity between spider communities declined as the geographic distance between sites increased. Environmental variables also influenced community composition; stochastic events and abiotic forces were the principal intervening factors in assembly structure. The differential dispersal capacity of spider groups also influenced community structure at a regional scale. The regional beta-diversity, as well as species replacement, was greater in high and intermediate vagility spiders; while nesting was greater in spiders with low dispersion

  18. Animal coloration: sexy spider scales.

    PubMed

    Taylor, Lisa A; McGraw, Kevin J

    2007-08-01

    Many male jumping spiders display vibrant colors that are used in visual communication. A recent microscopic study on a jumping spider from Singapore shows that three-layered 'scale sandwiches' of chitin and air are responsible for producing their brilliant iridescent body coloration.

  19. Animal coloration: sexy spider scales.

    PubMed

    Taylor, Lisa A; McGraw, Kevin J

    2007-08-01

    Many male jumping spiders display vibrant colors that are used in visual communication. A recent microscopic study on a jumping spider from Singapore shows that three-layered 'scale sandwiches' of chitin and air are responsible for producing their brilliant iridescent body coloration. PMID:17686428

  20. Spider movement, UV reflectance and size, but not spider crypsis, affect the response of honeybees to Australian crab spiders.

    PubMed

    Llandres, Ana L; Rodríguez-Gironés, Miguel A

    2011-02-16

    According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees.

  1. Spider Movement, UV Reflectance and Size, but Not Spider Crypsis, Affect the Response of Honeybees to Australian Crab Spiders

    PubMed Central

    Llandres, Ana L.; Rodríguez-Gironés, Miguel A.

    2011-01-01

    According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees. PMID:21359183

  2. The impact of management strategies in apple orchards on the structural and functional diversity of epigeal spiders.

    PubMed

    Mazzia, Christophe; Pasquet, Alain; Caro, Gaël; Thénard, Jodie; Cornic, Jean-François; Hedde, Mickaël; Capowiez, Yvan

    2015-04-01

    Apple orchards are agro-ecosystems managed with high levels of inputs and especially pesticides. Epigeal spider communities were sampled in three seasons using pitfall traps in 19 apple orchards with four different management strategies (abandoned, under organic, Integrated Pest Management or conventional protection) and thus significantly different pesticide usage. The abundance and diversity of the spider communities was the highest in abandoned orchards. Higher diversity and evenness values were the only difference in spider communities from the organic orchards compared to the other commercial orchards. The analysis of five ecological traits (proportion of aeronauts, type of diet, overwintering stages, body size and maternal care), however, clearly showed differences in the spiders from the organic orchards. The spider species in the other commercial orchards were smaller and have higher dispersal abilities. Seven bioindicator species were identified in abandoned orchards, two species in organic ones (only Lycosidae) and one species in conventional orchards (Linyphiidae).

  3. When spiders appear suddenly: spider-phobic patients are distracted by task-irrelevant spiders.

    PubMed

    Gerdes, Antje B M; Alpers, Georg W; Pauli, Paul

    2008-02-01

    Fear is thought to facilitate the detection of threatening stimuli. Few studies have examined the effects of task-irrelevant phobic cues in search tasks that do not involve semantic categorization. In a combined reaction time and eye-tracking experiment we investigated whether peripheral visual cues capture initial attention and distract from the execution of goal-directed eye movements. Twenty-one spider-phobic patients and 21 control participants were instructed to search for a color singleton while ignoring task-irrelevant abrupt-onset distractors which contained either a small picture of a spider (phobic), a flower (non-phobic, but similar to spiders in shape), a mushroom (non-phobic, and not similar to spiders in shape), or no picture. As expected, patients' reaction times were longer on trials with spider distractors. However, eye movements revealed that this was not due to attentional capture by spider distractors; patients more often fixated on all distractors with pictures, but their reaction times were delayed by longer fixation durations on spider distractors. These data do not support automatic capture of attention by phobic cues but suggest that phobic patients fail to disengage attention from spiders.

  4. Male-directed infanticide in spider monkeys (Ateles spp.).

    PubMed

    Alvarez, Sara; Di Fiore, Anthony; Champion, Jane; Pavelka, Mary Susan; Páez, Johanna; Link, Andrés

    2015-04-01

    Infanticide is considered a conspicuous expression of sexual conflict amongst mammals, including at least 35 primate species. Here we describe two suspected and one attempted case of intragroup infanticide in spider monkeys that augment five prior cases of observed or suspected infanticide in this genus. Contrary to the typical pattern of infanticide seen in most primate societies, where infants are killed by conspecifics independent of their sex, all eight cases of observed or suspected infanticide in spider monkeys have been directed toward male infants within their first weeks of life. Moreover, although data are still scant, infanticides seem to be perpetrated exclusively by adult males against infants from their own social groups and are not associated with male takeovers or a sudden rise in male dominance rank. Although the slow reproductive cycles of spider monkeys might favor the presence of infanticide because of the potential to shorten females' interbirth intervals, infanticide is nonetheless uncommon among spider monkeys, and patterns of male-directed infanticide are not yet understood. We suggest that given the potentially close genetic relationships among adult males within spider monkey groups, and the need for males to cooperate with one another in territorial interactions with other groups of related males, infanticide may be expected to occur primarily where the level of intragroup competition among males outweighs that of competition between social groups. Finally, we suggest that infanticide in spider monkeys may be more prevalent than previously thought, given that it may be difficult for observers to witness cases of infanticide or suspected infanticide that occur soon after birth in taxa that are characterized by high levels of fission-fusion dynamics. Early, undetected, male-biased infanticide could influence the composition of spider monkey groups and contribute to the female-biased adult sex ratios often reported for this genus.

  5. Investigating the influence of farm-scape geospatial characteristics on spider diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biodiversity is an important aspect of sustainable crop management and agricultural production. Maintaining biodiversity within agricultural ecosystems, especially in regards to predator species, promotes natural pest control and many other ecosystem services. Spiders (Araneae) often prey upon commo...

  6. Description of a new species of brooding spider crab in the genus Paranaxia Rathbun, 1924 (Brachyura: Majoidea), from northern Australia and Indonesia.

    PubMed

    Hosie, Andrew M; Hara, Ana

    2016-06-22

    A new species, Paranaxia keesingi sp. nov., is described based on specimens collected in northern Australia. The new species differs from its only congener, P. serpulifera (Guérin, 1832, in Guérin-Méneville 1829-1837), by several characters including carapace setation, sternal cavities, absence of a subhepatic spine, presence of a sharp spine on the posterodistal angle of the cheliped merus, relatively shorter chelipeds, and longer and more slender ambulatory legs. Morphological separation of the two species is supported by 12s rDNA sequence divergences of 7.4-8.2%. Like P. serpulifera, the newly described species exhibits direct development with females carrying juvenile individuals under the pleon. Both species are sympatric, but Paranaxia keesingi sp. nov. is found in deeper waters than P. serpulifera.

  7. Scrutinizing the datasets obtained from nanoscale features of spider silk fibres

    PubMed Central

    Silva, Luciano P; Rech, Elibio L

    2014-01-01

    Spider silk fibres share unprecedented structural and mechanical properties which span from the macroscale to nanoscale and beyond. This is possible due to the molecular features of modular proteins termed spidroins. Thus, the investigation of the organizational scaffolds observed for spidroins in spider silk fibres is of paramount importance for reverse bioengineering. This dataset consists in describing a rational screening procedure to identify the nanoscale features of spider silk fibres. Using atomic force microscopy operated in multiple acquisition modes, we evaluated silk fibres from nine spider species. Here we present the complete results of the analyses and decrypted a number of novel features that could even rank the silk fibres according to desired mechanostructural features. This dataset will allow other researchers to select the most appropriate models for synthetic biology and also lead to better understanding of spider silk fibres extraordinary performance that is comparable to the best manmade materials. PMID:25977795

  8. Scrutinizing the datasets obtained from nanoscale features of spider silk fibres.

    PubMed

    Silva, Luciano P; Rech, Elibio L

    2014-01-01

    Spider silk fibres share unprecedented structural and mechanical properties which span from the macroscale to nanoscale and beyond. This is possible due to the molecular features of modular proteins termed spidroins. Thus, the investigation of the organizational scaffolds observed for spidroins in spider silk fibres is of paramount importance for reverse bioengineering. This dataset consists in describing a rational screening procedure to identify the nanoscale features of spider silk fibres. Using atomic force microscopy operated in multiple acquisition modes, we evaluated silk fibres from nine spider species. Here we present the complete results of the analyses and decrypted a number of novel features that could even rank the silk fibres according to desired mechanostructural features. This dataset will allow other researchers to select the most appropriate models for synthetic biology and also lead to better understanding of spider silk fibres extraordinary performance that is comparable to the best manmade materials. PMID:25977795

  9. Spatial distribution of Madeira Island Laurisilva endemic spiders (Arachnida: Araneae)

    PubMed Central

    2014-01-01

    Abstract Madeira island presents a unique spider diversity with a high number of endemic species, many of which are still poorly known. A recent biodiversity survey on the terrestrial arthropods of the native forest, Laurisilva, provided a large set of standardized samples from various patches throughout the island. Out of the fifty two species recorded, approximately 33.3% are Madeiran endemics, many of which had not been collected since their original description. Two new species to science are reported – Ceratinopsis n. sp. and Theridion n. sp. – and the first records of Poeciloneta variegata (Blackwall, 1841) and Tetragnatha intermedia Kulczynski, 1891 are reported for the first time for Madeira island. Considerations on species richness and abundance from different Laurisilva locations are presented, together with distribution maps for endemic species. These results contribute to a better understanding of spider diversity patterns and endemic species distribution in the native forest of Madeira island. PMID:24855443

  10. A new species of false spider crab of the genus Elamena H. Milne Edwards, 1837 (Crustacea: Decapoda: Brachyura: Hymenosomatidae), from Davao Gulf, Philippines.

    PubMed

    Husana, Daniel Edison M; Kase, Tomoki; Mendoza, Jose Christopher E

    2013-02-22

    A new species of hymenosomatid crab of the genus Elamena H. Milne Edwards, 1837, is described from the island of Samal, in the Davao Gulf, Mindanao, southern Philippines. Elamena samalensis sp. nov. belongs to the Elamena truncata species-group and is most similar to E. simplidenta Ng & Chuang, 1996, in the general form of the carapace and in the presence of only one subdistal tooth on the ambulatory dactyli. It can be distinguished from this species, however, by its more projecting rostrum, relatively longer and more slender ambulatory legs, and by the pointed apex of the female pleotelson.

  11. Hymenopteran parasitoids of the ant-eating spider Zodarion styliferum (Simon) (Araneae, Zodariidae)

    PubMed Central

    Korenko, Stanislav; Schmidt, Stefan; Schwarz, Martin; Gibson, Gary A.P.; Pekár, Stano

    2013-01-01

    Abstract Calymmochilus dispar Bouček & Andriescu (Hymenoptera, Eupelmidae) and Gelis apterus (Pontoppidan) (Hymenoptera, Ichneumonidae) are newly recorded as parasitoids of the ant-eating spider Zodarion styliferum (Simon) (Araneae, Zodariidae). The larvae of both parasitoid species fed on juvenile spiders. The final instar larva and pupa of Calymmochilus dispar and the male of Gelis apterus are described for the first time. Both species represent new distribution records for Portugal. The biology and host associations of the parasitoids are discussed. PMID:23653512

  12. Ant exclusion in citrus over an 8-year period reveals a pervasive yet changing effect of ants on a Mediterranean spider assemblage.

    PubMed

    Mestre, L; Piñol, J; Barrientos, J A; Espadaler, X

    2013-09-01

    Ants and spiders are ubiquitous generalist predators that exert top-down control on herbivore populations. Research shows that intraguild interactions between ants and spiders can negatively affect spider populations, but there is a lack of long-term research documenting the strength of such interactions and the potentially different effects of ants on the diverse array of species in a spider assemblage. Similarly, the suitability of family-level surrogates for finding patterns revealed by species-level data (taxonomic sufficiency) has almost never been tested in spider assemblages. We present a long-term study in which we tested the impact of ants on the spider assemblage of a Mediterranean citrus grove by performing sequential 1-year experimental exclusions on tree canopies for 8 years. We found that ants had a widespread influence on the spider assemblage, although the effect was only evident in the last 5 years of the study. During those years, ants negatively affected many spiders, and effects were especially strong for sedentary spiders. Analyses at the family level also detected assemblage differences between treatments, but they concealed the different responses to ant exclusion shown by some related spider species. Our findings show that the effects of experimental manipulations in ecology can vary greatly over time and highlight the need for long-term studies to document species interactions.

  13. Taxonomy and ecology of the Cape Town Spider Crab, Macropodia falcifera (Stimpson, 1858) (Crustacea: Decapoda: Brachyura: Inachidae).

    PubMed

    Ng, Peter K L; Richer De Forges, Bertrand; Jones, Georgina

    2013-01-01

    The nomenclature and taxonomy of the Cape Town Spider Crab, Macropodia falcifera Stimpson, 1858, is treated. The species is rediagnosed and figured, and its ecology discussed. A key is also provided of the Indo-West Pacific species of Macropodia.

  14. 'Gumdrop Meets Spider'

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Apollo 9 Command/Service Modules (CSM) nicknamed 'Gumdrop' and Lunar Module (LM), nicknamed 'Spider' are shown docked together as Command Module pilot David R. Scott stands in the open hatch. Astronaut Russell L. Schweickart, Lunar Module pilot, took this photograph of Scott during his EVA as he stood on the porch outside the Lunar Module. Apollo 9 was an Earth orbital mission designed to test docking procedures between the CSM and LM as well as test fly the Lunar Module in the relative safe confines of Earth orbit.

  15. 'Spider' Over The Ocean

    NASA Technical Reports Server (NTRS)

    1969-01-01

    View of the Apollo 9 Lunar Module 'Spider,' in a lunar landing configuration, as photographed form the Command/Service Module on the fifth day of the Apollo 9 earth-orbital mission. The landing gear on the Lunar Module has been deployed. Note Lunar Module's upper hatch and docking tunnel. The EVA foot restraints known as the 'Golden Slippers' are visible on the porch of the Lunar Module (LM). They allowed Lunar Module pilot Russell 'Rusty' Schweickart to securely stand on the porch during his EVA thus allowing him free use of his hands.

  16. Recent Advances in Research on Widow Spider Venoms and Toxins.

    PubMed

    Yan, Shuai; Wang, Xianchun

    2015-11-27

    Widow spiders have received much attention due to the frequently reported human and animal injures caused by them. Elucidation of the molecular composition and action mechanism of the venoms and toxins has vast implications in the treatment of latrodectism and in the neurobiology and pharmaceutical research. In recent years, the studies of the widow spider venoms and the venom toxins, particularly the α-latrotoxin, have achieved many new advances; however, the mechanism of action of the venom toxins has not been completely clear. The widow spider is different from many other venomous animals in that it has toxic components not only in the venom glands but also in other parts of the adult spider body, newborn spiderlings, and even the eggs. More recently, the molecular basis for the toxicity outside the venom glands has been systematically investigated, with four proteinaceous toxic components being purified and preliminarily characterized, which has expanded our understanding of the widow spider toxins. This review presents a glance at the recent advances in the study on the venoms and toxins from the Latrodectus species.

  17. Biotechnological Trends in Spider and Scorpion Antivenom Development.

    PubMed

    Laustsen, Andreas Hougaard; Solà, Mireia; Jappe, Emma Christine; Oscoz, Saioa; Lauridsen, Line Præst; Engmark, Mikael

    2016-07-23

    Spiders and scorpions are notorious for their fearful dispositions and their ability to inject venom into prey and predators, causing symptoms such as necrosis, paralysis, and excruciating pain. Information on venom composition and the toxins present in these species is growing due to an interest in using bioactive toxins from spiders and scorpions for drug discovery purposes and for solving crystal structures of membrane-embedded receptors. Additionally, the identification and isolation of a myriad of spider and scorpion toxins has allowed research within next generation antivenoms to progress at an increasingly faster pace. In this review, the current knowledge of spider and scorpion venoms is presented, followed by a discussion of all published biotechnological efforts within development of spider and scorpion antitoxins based on small molecules, antibodies and fragments thereof, and next generation immunization strategies. The increasing number of discovery and development efforts within this field may point towards an upcoming transition from serum-based antivenoms towards therapeutic solutions based on modern biotechnology.

  18. Recent Advances in Research on Widow Spider Venoms and Toxins

    PubMed Central

    Yan, Shuai; Wang, Xianchun

    2015-01-01

    Widow spiders have received much attention due to the frequently reported human and animal injures caused by them. Elucidation of the molecular composition and action mechanism of the venoms and toxins has vast implications in the treatment of latrodectism and in the neurobiology and pharmaceutical research. In recent years, the studies of the widow spider venoms and the venom toxins, particularly the α-latrotoxin, have achieved many new advances; however, the mechanism of action of the venom toxins has not been completely clear. The widow spider is different from many other venomous animals in that it has toxic components not only in the venom glands but also in other parts of the adult spider body, newborn spiderlings, and even the eggs. More recently, the molecular basis for the toxicity outside the venom glands has been systematically investigated, with four proteinaceous toxic components being purified and preliminarily characterized, which has expanded our understanding of the widow spider toxins. This review presents a glance at the recent advances in the study on the venoms and toxins from the Latrodectus species. PMID:26633495

  19. Biotechnological Trends in Spider and Scorpion Antivenom Development.

    PubMed

    Laustsen, Andreas Hougaard; Solà, Mireia; Jappe, Emma Christine; Oscoz, Saioa; Lauridsen, Line Præst; Engmark, Mikael

    2016-01-01

    Spiders and scorpions are notorious for their fearful dispositions and their ability to inject venom into prey and predators, causing symptoms such as necrosis, paralysis, and excruciating pain. Information on venom composition and the toxins present in these species is growing due to an interest in using bioactive toxins from spiders and scorpions for drug discovery purposes and for solving crystal structures of membrane-embedded receptors. Additionally, the identification and isolation of a myriad of spider and scorpion toxins has allowed research within next generation antivenoms to progress at an increasingly faster pace. In this review, the current knowledge of spider and scorpion venoms is presented, followed by a discussion of all published biotechnological efforts within development of spider and scorpion antitoxins based on small molecules, antibodies and fragments thereof, and next generation immunization strategies. The increasing number of discovery and development efforts within this field may point towards an upcoming transition from serum-based antivenoms towards therapeutic solutions based on modern biotechnology. PMID:27455327

  20. Biotechnological Trends in Spider and Scorpion Antivenom Development

    PubMed Central

    Laustsen, Andreas Hougaard; Solà, Mireia; Jappe, Emma Christine; Oscoz, Saioa; Lauridsen, Line Præst; Engmark, Mikael

    2016-01-01

    Spiders and scorpions are notorious for their fearful dispositions and their ability to inject venom into prey and predators, causing symptoms such as necrosis, paralysis, and excruciating pain. Information on venom composition and the toxins present in these species is growing due to an interest in using bioactive toxins from spiders and scorpions for drug discovery purposes and for solving crystal structures of membrane-embedded receptors. Additionally, the identification and isolation of a myriad of spider and scorpion toxins has allowed research within next generation antivenoms to progress at an increasingly faster pace. In this review, the current knowledge of spider and scorpion venoms is presented, followed by a discussion of all published biotechnological efforts within development of spider and scorpion antitoxins based on small molecules, antibodies and fragments thereof, and next generation immunization strategies. The increasing number of discovery and development efforts within this field may point towards an upcoming transition from serum-based antivenoms towards therapeutic solutions based on modern biotechnology. PMID:27455327

  1. David and Goliath: potent venom of an ant-eating spider (Araneae) enables capture of a giant prey

    NASA Astrophysics Data System (ADS)

    Pekár, Stano; Šedo, Onřej; Líznarová, Eva; Korenko, Stanislav; Zdráhal, Zdeněk

    2014-07-01

    It is rare to find a true predator that repeatedly and routinely kills prey larger than itself. A solitary specialised ant-eating spider of the genus Zodarion can capture a relatively giant prey. We studied the trophic niche of this spider species and investigated its adaptations (behavioural and venomic) that are used to capture ants. We found that the spider captures mainly polymorphic Messor arenarius ants. Adult female spiders captured large morphs while tiny juveniles captured smaller morphs, yet in both cases ants were giant in comparison with spider size. All specimens used an effective prey capture strategy that protected them from ant retaliation. Juvenile and adult spiders were able to paralyse their prey using a single bite. The venom glands of adults were more than 50 times larger than those of juvenile spiders, but the paralysis latency of juveniles was 1.5 times longer. This suggests that this spider species possesses very potent venom already at the juvenile stage. Comparison of the venom composition between juvenile and adult spiders did not reveal significant differences. We discovered here that specialised capture combined with very effective venom enables the capture of giant prey.

  2. David and Goliath: potent venom of an ant-eating spider (Araneae) enables capture of a giant prey.

    PubMed

    Pekár, Stano; Šedo, Onřej; Líznarová, Eva; Korenko, Stanislav; Zdráhal, Zdeněk

    2014-07-01

    It is rare to find a true predator that repeatedly and routinely kills prey larger than itself. A solitary specialised ant-eating spider of the genus Zodarion can capture a relatively giant prey. We studied the trophic niche of this spider species and investigated its adaptations (behavioural and venomic) that are used to capture ants. We found that the spider captures mainly polymorphic Messor arenarius ants. Adult female spiders captured large morphs while tiny juveniles captured smaller morphs, yet in both cases ants were giant in comparison with spider size. All specimens used an effective prey capture strategy that protected them from ant retaliation. Juvenile and adult spiders were able to paralyse their prey using a single bite. The venom glands of adults were more than 50 times larger than those of juvenile spiders, but the paralysis latency of juveniles was 1.5 times longer. This suggests that this spider species possesses very potent venom already at the juvenile stage. Comparison of the venom composition between juvenile and adult spiders did not reveal significant differences. We discovered here that specialised capture combined with very effective venom enables the capture of giant prey.

  3. Association and reversal learning abilities in a jumping spider.

    PubMed

    Liedtke, Jannis; Schneider, Jutta M

    2014-03-01

    The ability to learn and overwrite learned associations allows animals to respond adaptively to changes in their environment. However, such behavioural plasticity is presumed to be costly and the question arises to which extent animals with restricted neuronal capacity are capable of such flexible behaviour. In this study, we investigated the learning and reversal learning abilities of a jumping spider (Marpissa muscosa). In two discrimination tasks spiders had to associate colour in the first task and colour or location in the second task as a predictor of a food reward. Results show that spiders were able to quickly form and reverse associations. Individuals show differences in their learning success and in their preference of which cues they used (colour vs. location) as a reward's predictor. These results highlight the potential for flexible behaviour in species with small neuronal capacities and short life spans. PMID:24406509

  4. Mate Selection and Mating Behaviour in Spider Crabs

    NASA Astrophysics Data System (ADS)

    Jones, D. R.; Hartnoll, R. G.

    1997-02-01

    Female spider crabs can only mate after the terminal moult, which means that they must either mate whilst soft-shelled after moulting, or subsequently when hard-shelled. There is evidence that some, at least, do both, whereas the majority of crabs mate in only one or other of these states. The mating behaviour, and the means of detecting receptive females, have been studied in a spider crab, Inachus dorsettensis. In this species, mating is predominantly hard-shelled, and receptive females are recognized by their emission of chemical pheromones. The implications of the behaviour patterns for male mating efficiency, sperm competition and female reproductive success are discussed. Mate selection and mating behaviour in other spider crabs are compared with I. dorsettensis. Reasons for similarities and differences are reviewed.

  5. Prey interception drives web invasion and spider size determines successful web takeover in nocturnal orb-web spiders

    PubMed Central

    Gan, Wenjin; Liu, Shengjie; Yang, Xiaodong; Li, Daiqin; Lei, Chaoliang

    2015-01-01

    ABSTRACT A striking feature of web-building spiders is the use of silk to make webs, mainly for prey capture. However, building a web is energetically expensive and increases the risk of predation. To reduce such costs and still have access to abundant prey, some web-building spiders have evolved web invasion behaviour. In general, no consistent patterns of web invasion have emerged and the factors determining web invasion remain largely unexplored. Here we report web invasion among conspecifics in seven nocturnal species of orb-web spiders, and examined the factors determining the probability of webs that could be invaded and taken over by conspecifics. About 36% of webs were invaded by conspecifics, and 25% of invaded webs were taken over by the invaders. A web that was built higher and intercepted more prey was more likely to be invaded. Once a web was invaded, the smaller the size of the resident spider, the more likely its web would be taken over by the invader. This study suggests that web invasion, as a possible way of reducing costs, may be widespread in nocturnal orb-web spiders. PMID:26405048

  6. Prey interception drives web invasion and spider size determines successful web takeover in nocturnal orb-web spiders.

    PubMed

    Gan, Wenjin; Liu, Shengjie; Yang, Xiaodong; Li, Daiqin; Lei, Chaoliang

    2015-09-24

    A striking feature of web-building spiders is the use of silk to make webs, mainly for prey capture. However, building a web is energetically expensive and increases the risk of predation. To reduce such costs and still have access to abundant prey, some web-building spiders have evolved web invasion behaviour. In general, no consistent patterns of web invasion have emerged and the factors determining web invasion remain largely unexplored. Here we report web invasion among conspecifics in seven nocturnal species of orb-web spiders, and examined the factors determining the probability of webs that could be invaded and taken over by conspecifics. About 36% of webs were invaded by conspecifics, and 25% of invaded webs were taken over by the invaders. A web that was built higher and intercepted more prey was more likely to be invaded. Once a web was invaded, the smaller the size of the resident spider, the more likely its web would be taken over by the invader. This study suggests that web invasion, as a possible way of reducing costs, may be widespread in nocturnal orb-web spiders.

  7. Prey interception drives web invasion and spider size determines successful web takeover in nocturnal orb-web spiders.

    PubMed

    Gan, Wenjin; Liu, Shengjie; Yang, Xiaodong; Li, Daiqin; Lei, Chaoliang

    2015-01-01

    A striking feature of web-building spiders is the use of silk to make webs, mainly for prey capture. However, building a web is energetically expensive and increases the risk of predation. To reduce such costs and still have access to abundant prey, some web-building spiders have evolved web invasion behaviour. In general, no consistent patterns of web invasion have emerged and the factors determining web invasion remain largely unexplored. Here we report web invasion among conspecifics in seven nocturnal species of orb-web spiders, and examined the factors determining the probability of webs that could be invaded and taken over by conspecifics. About 36% of webs were invaded by conspecifics, and 25% of invaded webs were taken over by the invaders. A web that was built higher and intercepted more prey was more likely to be invaded. Once a web was invaded, the smaller the size of the resident spider, the more likely its web would be taken over by the invader. This study suggests that web invasion, as a possible way of reducing costs, may be widespread in nocturnal orb-web spiders. PMID:26405048

  8. Host Specificity and Temporal and Seasonal Shifts in Host Preference of a Web-Spider Parasitoid Zatypota percontatoria

    PubMed Central

    Korenko, Stanislav; Michalková, Veronika; Zwakhals, Kees; Pekár, Stano

    2011-01-01

    Current knowledge about polysphinctine parasite wasps' interactions with their spider hosts is very fragmented and incomplete. This study presents the host specificity of Zatypota percontatoria (Müller) (Hymenoptera: Ichneumonidae) and its adaptation to varying host availability. Two years of field observations show that Z. percontatoria is a stenophagous parasitoid that parasitizes only five closely related web-building spiders of the family Theridiidae (Araneae). Within the Theridiidae it attacks only species belonging to a small group of species, here called the “Theridion” group. These hosts have a similar biology, but are available at different levels of abundance and at different sizes over the season. Laboratory experiments showed that this wasp species ignores linyphiid, araneid or dictynid spiders and accepts only theridiid spiders of the “Theridion” group. In the field study, wasp females preferred older juvenile and sub-adult female spider instars with intermediate body size. Only 5% of the parasitized spiders were males. Parasitism in the natural population of theridiid spiders was on average 1.3%. Parasitism was most frequent on two species, Theridion varians Hahn in 2007 and Neottiura bimaculata Linnaeus in 2008. The parasitization rate was positively correlated with spider abundance. The wasp responded adaptively to seasonal changes in host abundance and host body size and shifted host preference according to the availability of suitable hosts during, as well as between, seasons. In spring and summer the highest percentage of parasitism was on T. varians and in autumn it was on N. bimaculata. PMID:22216929

  9. Interactions Between the Chilean Recluse Spider (Araneae: Sicariidae) and an Araneophagic Spitting Spider (Araneae: Scytodidae).

    PubMed

    Canals, Mauricio; Arriagada, Nicolás; Solís, Rigoberto

    2015-03-01

    In Chile, all necrotic arachnidism is attributed to the Chilean recluse spider, Loxosceles laeta Nicolet, a species that shares the microenvironmental habitats with the spitting spider Scytodes globula Nicolet. The latter species has been proposed as a potential predator of L. laeta. For this research, we studied the interaction between both species during individual encounters to assess the possibility of population regulation of L. laeta cohorts exposed to this potential predator. We found that in most encounters S. globula prevailed. Also, S. globula preys on spiderlings of L. laeta, with a population effect on cohorts of this species. These findings suggest that S. globula may be influencing L. laeta populations in central Chile. The population regulation of L. laeta by predation would be important because this species, in the absence of predators, has a high reproductive rate, and it can maintain populations of large size. However according to our results, although S. globula may aid in the reduction of both spiderling and adult L. laeta populations, and perhaps other Loxosceles species, it is insufficient for biological control of Loxosceles species. Its presence together with other control measures such as hygiene of the rooms can help to decrease loxoscelism incidence. PMID:26336293

  10. Molecular characterization and evolutionary study of spider tubuliform (eggcase) silk protein.

    PubMed

    Tian, Maozhen; Lewis, Randolph V

    2005-06-01

    As a result of hundreds of millions of years of evolution, orb-web-weaving spiders have developed the use of seven different silks produced by different abdominal glands for various functions. Tubuliform silk (eggcase silk) is unique among these spider silks due to its high serine and very low glycine content. In addition, tubuliform silk is the only silk produced just during a short period of time, the reproductive season, in the spider's life. To understand the molecular characteristics of the proteins composing this silk, we constructed tubuliform-gland-specific cDNA libraries from three different spider families, Nephila clavipes, Argiope aurantia, and Araneus gemmoides. Sequencing of tubuliform silk cDNAs reveals the repetitive architecture of its coding sequence and novel amino acid motifs. The inferred protein, tubuliform spidroin 1 (TuSp1), contains highly homogenized repeats in all three spiders. Amino acid composition comparison of the predicted tubuliform silk protein sequence to tubuliform silk indicates that TuSp1 is the major component of tubuliform silk. Repeat unit alignment of TuSp1 among three spider species shows high sequence conservation among tubuliform silk protein orthologue groups. Sequence comparison among TuSp1 repetitive units within species suggests intragenic concerted evolution, presumably through gene conversion and unequal crossover events. Comparative analysis demonstrates that TuSp1 represents a new orthologue in the spider silk gene family.

  11. Comparative Growth and Development of Spiders Reared on Live and Dead Prey

    PubMed Central

    Peng, Yu; Zhang, Fan; Gui, Shaolan; Qiao, Huping; Hose, Grant C.

    2013-01-01

    Scavenging (feeding on dead prey) has been demonstrated across a number of spider families, yet the implications of feeding on dead prey for the growth and development of individuals and population is unknown. In this study we compare the growth, development, and predatory activity of two species of spiders that were fed on live and dead prey. Pardosa astrigera (Lycosidae) and Hylyphantes graminicola (Lyniphiidae) were fed live or dead fruit flies, Drosophila melanogaster. The survival of P. astrigera and H. graminicola was not affected by prey type. The duration of late instars of P. astrigera fed dead prey were longer and mature spiders had less protein content than those fed live prey, whereas there were no differences in the rate of H. graminicola development, but the mass of mature spiders fed dead prey was greater than those fed live prey. Predation rates by P. astrigera did not differ between the two prey types, but H. graminicola had a higher rate of predation on dead than alive prey, presumably because the dead flies were easier to catch and handle. Overall, the growth, development and reproduction of H. graminicola reared with dead flies was better than those reared on live flies, yet for the larger P. astrigera, dead prey may suit smaller instars but mature spiders may be best maintained with live prey. We have clearly demonstrated that dead prey may be suitable for rearing spiders, although the success of the spiders fed such prey appears size- and species specific. PMID:24386248

  12. Mechanical behavior of silk during the evolution of orb-web spinning spiders.

    PubMed

    Elices, Manuel; Plaza, Gustavo R; Arnedo, Miquel A; Pérez-Rigueiro, José; Torres, Fernando G; Guinea, Gustavo V

    2009-07-13

    The development of an accurate and reproducible approach to measuring the tensile behavior of spider silk has allowed characterizing and comparing the range of mechanical properties exhibited by different spider species with unprecedented detail. The comparison of silks spun by spiders belonging to different phylogenetic groups has revealed that evolution locked in many of the important properties of spider silks very early in the history of orb-web weaving spiders, despite the fact that the silk gland system is relatively isolated in physiological terms from the rest of the organism and should thus mutate quickly. The variations observed between species may be grouped in at least two patterns that are shown not to be related to phylogeny. Beyond the relevance of these results for the evolutionary biology of spiders and silks, the conservation of the basic traits observed in the mechanical behavior of spider silks is likely to set a limit to the range of properties that can be expected from artificial fibers bioinspired in natural silks.

  13. Dynamics of spider glue adhesion: effect of surface energy and contact area

    NASA Astrophysics Data System (ADS)

    Amarpuri, Gaurav; Chen, Yizhou; Blackledge, Todd; Dhinojwala, Ali

    Spider glue is a unique biological adhesive which is humidity responsive such that the adhesion continues to increase upto 100% relative humidity (RH) for some species. This is unlike synthetic adhesives that significantly drop in adhesion with an increase in humidity. However, most of adhesion data reported in literature have used clean hydrophilic glass substrate, unlike the hydrophobic, and charged insect cuticle surface that adheres to spider glue in nature. Previously, we have reported that the spider glue viscosity changes over five orders of magnitude with humidity. Here, we vary the surface energy and surface charge of the substrate to test the change in Larnioides cornutus spider glue adhesion with humidity. We find that an increase in both surface energy and surface charge density increases the droplet spreading and there exists an optimum droplet contact area where adhesion is maximized. Moreover, spider glue droplets act as reusable adhesive for low energy hydrophobic surface at the optimum humidity. These results explain why certain prey are caught more efficiently by spiders in their habitat. The mechanism by which spider species tune its glue adhesion for local prey capture can inspire new generation smart adhesives.

  14. Climatic Variables Do Not Directly Predict Spider Richness and Abundance in Semiarid Caatinga Vegetation, Brazil.

    PubMed

    Carvalho, Leonardo S; Sebastian, Nicholas; Araújo, Helder F P; Dias, Sidclay C; Venticinque, Eduardo; Brescovit, Antonio D; Vasconcellos, Alexandre

    2015-02-01

    Spiders are abundant in tropical ecosystems and exert predatory pressure on a wide variety of invertebrate populations and also serve as prey for many others organisms, being part of complex interrelationships influenced directly and indirectly by a myriad of factors. We examined the influence of biotic (i.e., prey availability) and abiotic (i.e., temperature, precipitation, relative humidity, real evapotranspiration) factors on species richness and abundance during a two-year period in the semiarid Caatinga vegetation in northeastern Brazil. Data were analyzed through partial autocorrelation functions, cross correlations, and a path analysis. A total of 2522 spiders were collected with beating tray, pit-fall traps, and malaise traps, comprising 91 species and 34 families. Spider abundance peaked in the rainy season. Our results suggest that total invertebrate abundance has a direct influence on spider richness and abundance, whereas the effects of precipitation were mainly indirectly related to most spider assemblage parameters. The increase in vegetation cover with the rainy season in the Caatinga provides more breeding and foraging sites for spiders and stimulates their activities. Additionally, rainfall in arid and semiarid ecosystems stimulated the activity and reproduction of many herbivore and detritivore invertebrates dependent on plant biomass and necromass consumption, leading to an increase in spider prey availability.

  15. Climatic Variables Do Not Directly Predict Spider Richness and Abundance in Semiarid Caatinga Vegetation, Brazil.

    PubMed

    Carvalho, Leonardo S; Sebastian, Nicholas; Araújo, Helder F P; Dias, Sidclay C; Venticinque, Eduardo; Brescovit, Antonio D; Vasconcellos, Alexandre

    2015-02-01

    Spiders are abundant in tropical ecosystems and exert predatory pressure on a wide variety of invertebrate populations and also serve as prey for many others organisms, being part of complex interrelationships influenced directly and indirectly by a myriad of factors. We examined the influence of biotic (i.e., prey availability) and abiotic (i.e., temperature, precipitation, relative humidity, real evapotranspiration) factors on species richness and abundance during a two-year period in the semiarid Caatinga vegetation in northeastern Brazil. Data were analyzed through partial autocorrelation functions, cross correlations, and a path analysis. A total of 2522 spiders were collected with beating tray, pit-fall traps, and malaise traps, comprising 91 species and 34 families. Spider abundance peaked in the rainy season. Our results suggest that total invertebrate abundance has a direct influence on spider richness and abundance, whereas the effects of precipitation were mainly indirectly related to most spider assemblage parameters. The increase in vegetation cover with the rainy season in the Caatinga provides more breeding and foraging sites for spiders and stimulates their activities. Additionally, rainfall in arid and semiarid ecosystems stimulated the activity and reproduction of many herbivore and detritivore invertebrates dependent on plant biomass and necromass consumption, leading to an increase in spider prey availability. PMID:26308806

  16. Comparative growth and development of spiders reared on live and dead prey.

    PubMed

    Peng, Yu; Zhang, Fan; Gui, Shaolan; Qiao, Huping; Hose, Grant C

    2013-01-01

    Scavenging (feeding on dead prey) has been demonstrated across a number of spider families, yet the implications of feeding on dead prey for the growth and development of individuals and population is unknown. In this study we compare the growth, development, and predatory activity of two species of spiders that were fed on live and dead prey. Pardosa astrigera (Lycosidae) and Hylyphantes graminicola (Lyniphiidae) were fed live or dead fruit flies, Drosophila melanogaster. The survival of P. astrigera and H. graminicola was not affected by prey type. The duration of late instars of P. astrigera fed dead prey were longer and mature spiders had less protein content than those fed live prey, whereas there were no differences in the rate of H. graminicola development, but the mass of mature spiders fed dead prey was greater than those fed live prey. Predation rates by P. astrigera did not differ between the two prey types, but H. graminicola had a higher rate of predation on dead than alive prey, presumably because the dead flies were easier to catch and handle. Overall, the growth, development and reproduction of H. graminicola reared with dead flies was better than those reared on live flies, yet for the larger P. astrigera, dead prey may suit smaller instars but mature spiders may be best maintained with live prey. We have clearly demonstrated that dead prey may be suitable for rearing spiders, although the success of the spiders fed such prey appears size- and species specific.

  17. Cell culture's spider silk road.

    PubMed

    Perkel, Jeffrey

    2014-06-01

    A number of synthetic and natural materials have been tried in cell culture and tissue engineering applications in recent years. Now Jeffrey Perkel takes a look at one new culture component that might surprise you-spider silk.

  18. Cell culture's spider silk road.

    PubMed

    Perkel, Jeffrey

    2014-06-01

    A number of synthetic and natural materials have been tried in cell culture and tissue engineering applications in recent years. Now Jeffrey Perkel takes a look at one new culture component that might surprise you-spider silk. PMID:24924388

  19. Structural color and its interaction with other color-producing elements: perspectives from spiders

    NASA Astrophysics Data System (ADS)

    Hsiung, Bor-Kai; Blackledge, Todd A.; Shawkey, Matthew D.

    2014-09-01

    Structural color is produced when nanostructures called schemochromes alter light reflected from a surface through different optic principles, in contrast with other types of colors that are produced when pigments selectively absorb certain wavelengths of light. Research on biogenic photonic nanostructures has focused primarily on bird feathers, butterfly wings and beetle elytra, ignoring other diverse groups such as spiders. We argue that spiders are a good model system to study the functions and evolution of colors in nature for the following reasons. First, these colors clearly function in spiders such as the tarantulas outside of sexual selection, which is likely the dominant driver of the evolution of structural colors in birds and butterflies. Second, within more than 44,000 currently known spider species, colors are used in every possible way based on the same sets of relatively simple materials. Using spiders, we can study how colors evolve to serve different functions under a variety of combinations of driving forces, and how those colors are produced within a relatively simple system. Here, we first review the different color-producing materials and mechanisms (i.e., light absorbing, reflecting and emitting) in birds, butterflies and beetles, the interactions between these different elements, and the functions of colors in different organisms. We then summarize the current state of knowledge of spider colors and compare it with that of birds and insects. We then raise questions including: 1. Could spiders use fluorescence as a mechanism to protect themselves from UV radiation, if they do not have the biosynthetic pathways to produce melanins? 2. What functions could color serve for nearly blind tarantulas? 3. Why are only multilayer nanostructures (thus far) found in spiders, while birds and butterflies use many diverse nanostructures? And, does this limit the diversity of structural colors found in spiders? Answering any of these questions in the future

  20. Trophic overlap between fish and riparian spiders: potential impacts of an invasive fish on terrestrial consumers.

    PubMed

    Jackson, Michelle C; Woodford, Darragh J; Bellingan, Terence A; Weyl, Olaf L F; Potgieter, Michael J; Rivers-Moore, Nick A; Ellender, Bruce R; Fourie, Hermina E; Chimimba, Christian T

    2016-03-01

    Studies on resource sharing and partitioning generally consider species that occur in the same habitat. However, subsidies between linked habitats, such as streams and riparian zones, create potential for competition between populations which never directly interact. Evidence suggests that the abundance of riparian consumers declines after fish invasion and a subsequent increase in resource sharing of emerging insects. However, diet overlap has not been investigated. Here, we examine the trophic niche of native fish, invasive fish, and native spiders in South Africa using stable isotope analysis. We compared spider abundance and diet at upstream fishless and downstream fish sites and quantified niche overlap with invasive and native fish. Spider abundance was consistently higher at upstream fishless sites compared with paired downstream fish sites, suggesting that the fish reduced aquatic resource availability to riparian consumers. Spiders incorporated more aquatic than terrestrial insects in their diet, with aquatic insects accounting for 45-90% of spider mass. In three of four invaded trout rivers, we found that the average proportion of aquatic resources in web-building spider diet was higher at fishless sites compared to fish sites. The probability of web-building and ground spiders overlapping into the trophic niche of invasive brown and rainbow trout was as high as 26 and 51%, respectively. In contrast, the probability of spiders overlapping into the trophic niche of native fish was always less than 5%. Our results suggest that spiders share resources with invasive fish. In contrast, spiders had a low probability of trophic overlap with native fish indicating that the traits of invaders may be important in determining their influence on ecosystem subsidies. We have added to the growing body of evidence that invaders can have cross-ecosystem impacts and demonstrated that this can be due to niche overlap. PMID:27087934

  1. Personnel in Mission Control examine replica of spider habitat from Skylab 3

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Flight Director Neil B. Hutchinson, left, and Astronaut Bruce McCandless II hold up a glass enclosure - home for the spider Arachne, which is the same species as the two spiders carried on the Skylab 3 mission. The real spider is the one barely visible at the upper right corner of the square; the larger one is a projected image on the rear-screen-projected map in the front of the Mission Operations Control Room (MOCR) of the Mission Control Center (MCC). McCandless served as backup pilot for the first manned Skylab mission and was a spacecraft-communicater (CAPCOM) for the second crew.

  2. Spiders from Mars?

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-426, 19 July 2003

    No, this is not a picture of a giant, martian spider web. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of polygonal features on the floor of a northern hemisphere impact crater near 65.6oN, 327.7oW. The picture was acquired during spring, after the seasonal carbon dioxide frost cap had largely migrated through the region. At the time the picture was taken, remnants of seasonal frost remained on the crater rim and on the edges of the troughs that bound each of the polygons. Frost often provides a helpful hint as to where polygons and patterned ground occur. The polygons, if they were on Earth, would indicate the presence of freeze-thaw cycles in ground ice. Although uncertain, the same might be true of Mars. Sunlight illuminates the scene from the lower left.

  3. Mediation of a plant-spider association by specific volatile compounds.

    PubMed

    Nelson, Ximena J; Pratt, Andrew J; Cheseto, Xavier; Torto, Baldwyn; Jackson, Robert R

    2012-09-01

    Evarcha culicivora, an East African jumping spider (Salticidae), is the only spider for which there is evidence of innate olfactory affinity for particular plant species. Evarcha culicivora also actively chooses as preferred prey the females of Anopheles mosquitoes, and both sexes of Anopheles are known to visit plants for nectar meals. Here, we identified compounds present in the headspace of one of these species in Kenya, Lantana camara, and then used 11 of these compounds in olfactometer experiments. Our findings show that three terpenes [(E)-β-caryophyllene, α-humulene and 1,8 cineole] can be discriminated by, and are salient to, E. culicivora. The spiders experienced no prior training with plants or the compounds we used. This is the first experimental demonstration of specific phytochemicals being innately attractive to a spider, a group normally characterized as predators. PMID:22914959

  4. Reproductive Seasonality in Nesticus (Araneae: Nesticidae) Cave Spiders

    PubMed Central

    Carver, Linnea M.; Perlaky, Patricia; Cressler, Alan; Zigler, Kirk S.

    2016-01-01

    Spiders of the family Nesticidae are members of cave communities around the world with cave-obligate (troglobiotic) species known from North America, Europe, Asia and the Indo-Pacific. A radiation of Nesticus (Araneae: Nesticidae) in the southern Appalachians includes ten troglobiotic species. Many of these species are of conservation interest due to their small ranges, with four species being single-cave endemics. Despite conservation concerns and their important role as predators in cave communities, we know little about reproduction and feeding in this group. We addressed this knowledge gap by examining populations of two species on a monthly basis for one year. We made further observations on several other species and populations, totaling 671 individual spider observations. This more than doubled the reported observations of reproduction and feeding in troglobiotic Nesticus. Female Nesticus carry egg sacs, facilitating the determination of the timing and frequency of reproduction. We found that Nesticus exhibit reproductive seasonality. Females carried egg sacs from May through October, with a peak in frequency in June. These spiders were rarely observed with prey; only 3.3% (22/671) of individuals were observed with prey items. The frequency at which prey items were observed did not vary by season. Common prey items were flies, beetles and millipedes. Troglobiotic species constituted approximately half of all prey items observed. This result represents a greater proportion of troglobiotic prey than has been reported for various troglophilic spiders. Although our findings shed light on the life history of troglobiotic Nesticus and on their role in cave ecosystems, further work is necessary to support effective conservation planning for many of these rare species. PMID:27280416

  5. Reproductive Seasonality in Nesticus (Araneae: Nesticidae) Cave Spiders.

    PubMed

    Carver, Linnea M; Perlaky, Patricia; Cressler, Alan; Zigler, Kirk S

    2016-01-01

    Spiders of the family Nesticidae are members of cave communities around the world with cave-obligate (troglobiotic) species known from North America, Europe, Asia and the Indo-Pacific. A radiation of Nesticus (Araneae: Nesticidae) in the southern Appalachians includes ten troglobiotic species. Many of these species are of conservation interest due to their small ranges, with four species being single-cave endemics. Despite conservation concerns and their important role as predators in cave communities, we know little about reproduction and feeding in this group. We addressed this knowledge gap by examining populations of two species on a monthly basis for one year. We made further observations on several other species and populations, totaling 671 individual spider observations. This more than doubled the reported observations of reproduction and feeding in troglobiotic Nesticus. Female Nesticus carry egg sacs, facilitating the determination of the timing and frequency of reproduction. We found that Nesticus exhibit reproductive seasonality. Females carried egg sacs from May through October, with a peak in frequency in June. These spiders were rarely observed with prey; only 3.3% (22/671) of individuals were observed with prey items. The frequency at which prey items were observed did not vary by season. Common prey items were flies, beetles and millipedes. Troglobiotic species constituted approximately half of all prey items observed. This result represents a greater proportion of troglobiotic prey than has been reported for various troglophilic spiders. Although our findings shed light on the life history of troglobiotic Nesticus and on their role in cave ecosystems, further work is necessary to support effective conservation planning for many of these rare species. PMID:27280416

  6. Deer herbivory reduces web-building spider abundance by simplifying forest vegetation structure

    PubMed Central

    Chips, Michael J.; Carson, Walter P.

    2016-01-01

    Indirect ecological effects are a common feature of ecological systems, arising when one species affects interactions among two or more other species. We examined how browsing by white-tailed deer (Odocoileus virginianus) indirectly affected the abundance and composition of a web-building spider guild through their effects on the structure of the ground and shrub layers of northern hardwood forests. We examined paired plots consisting of deer-free and control plots in the Allegheny Plateau region Pennsylvania and Northern Highlands region of Wisconsin. We recorded the abundance of seven types of webs, each corresponding to a family of web-building spiders. We quantified vegetation structure and habitat suitability for the spiders by computing a web scaffold availability index (WSAI) at 0.5 m and 1.0 m above the ground. At Northern Highlands sites, we recorded prey availability. Spider webs were twice as abundant in deer-free plots compared to control plots, while WSAI was 7–12 times greater in deerfree plots. Prey availability was lower in deer-free plots. With the exception of funnel web-builders, all spider web types were significantly more abundant in deer-free plots. Both deer exclusion and the geographic region of plots were significant predictors of spider community structure. In closed canopy forests with high browsing pressure, the low density of tree saplings and shrubs provides few locations for web-building spiders to anchor webs. Recruitment of these spiders may become coupled with forest disturbance events that increase tree and shrub recruitment. By modifying habitat structure, deer appear to indirectly modify arthropod food web interactions. As deer populations have increased in eastern North America over the past several decades, the effects of deer on web-building spiders may be widespread. PMID:27703868

  7. Multiple origins of subsociality in crab spiders (Thomisidae).

    PubMed

    Ruch, Jasmin; Riehl, Torben; May-Collado, Laura J; Agnarsson, Ingi

    2015-01-01

    Determining factors that facilitate the transition from a solitary to a social lifestyle is a major challenge in evolutionary biology, especially in taxa that are usually aggressive towards conspecifics. Most spiders live solitarily and few species are known to be social. Nevertheless, sociality has evolved multiple times across several families and nearly all studied social lineages have originated from a periodically social (subsocial) ancestor. Group-living crab spiders (Thomisidae) are exclusively found in Australia and differ from most other social spiders because they lack a communal capture web. Three of the group-living species were placed in the genus Diaea and another in the genus Xysticus. Most Australian thomisids are, however, difficult to identify as most descriptions are old and of poor quality, and the genera Diaea and Xysticus may not correspond to monophyletic groups. Here, we clarify the phylogenetic relationships of the four group-living Australian thomisids and conclude that amongst these subsociality has evolved two to three times independently. The subsocial Xysticus bimaculatus is not closely related to any of the social Diaea and an independent origin of subsociality is likely in this case. The presented data indicates that within Diaea two origins of subsociality are possible. Our results help to understand the evolution of sociality in thomisids and support the hypothesis that permanent sociality in spiders has evolved multiple times relatively recently from subsocial ancestors.

  8. Competition between introduced and native spiders (Araneae: Linyphiidae)

    USGS Publications Warehouse

    Houser, J.D.; Ginsberg, Howard S.; Jakob, Elizabeth M.

    2014-01-01

    The European sheet-web spider Linyphia triangularis (Araneae: Linyphiidae) has become established in Maine, where it often reaches very high densities. Two lines of evidence from previous work suggest that L. triangularis affects populations of the native linyphiid spider Frontinella communis. First, F. communis individuals are relatively scarce in both forest and coastal habitat where L. triangularis is common, but more common where L. triangularis is at low density. Second, in field experiments, F. communis species are less likely to settle in experimental plots when L. triangularis is present, and F. communis disappears from study plots when L. triangularis is introduced. Here we test two mechanisms that may underlie these patterns. First, we tested whether L. triangularis invades and usurps the webs of F. communis. When spiders were released onto webs of heterospecifics, L. triangularis was more likely to take over or share webs of F. communis than the reverse. We also observed natural takeovers of F. communis webs. Second, we explored the hypothesis that L. triangularis reduces prey availability for native species. We sampled flying prey in areas with L. triangularis and those where it had been removed, and found no effect of spider presence on measured prey density. We also found no effect of prey supplementation on web tenacity in F. communis, suggesting that F. communis movements are not highly dependent on prey availability. We conclude that web takeover is likely more important than prey reduction in driving negative effects of L. triangularis on F. communis.

  9. Spider phylogenomics: untangling the Spider Tree of Life

    PubMed Central

    Garrison, Nicole L.; Rodriguez, Juanita; Agnarsson, Ingi; Coddington, Jonathan A.; Griswold, Charles E.; Hamilton, Christopher A.; Hedin, Marshal; Kocot, Kevin M.; Ledford, Joel M.

    2016-01-01

    Spiders (Order Araneae) are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet and have persisted for over 380 million years. Spiders have long served as evolutionary models for studying complex mating and web spinning behaviors, key innovation and adaptive radiation hypotheses, and have been inspiration for important theories like sexual selection by female choice. Unfortunately, past major attempts to reconstruct spider phylogeny typically employing the “usual suspect” genes have been unable to produce a well-supported phylogenetic framework for the entire order. To further resolve spider evolutionary relationships we have assembled a transcriptome-based data set comprising 70 ingroup spider taxa. Using maximum likelihood and shortcut coalescence-based approaches, we analyze eight data sets, the largest of which contains 3,398 gene regions and 696,652 amino acid sites forming the largest phylogenomic analysis of spider relationships produced to date. Contrary to long held beliefs that the orb web is the crowning achievement of spider evolution, ancestral state reconstructions of web type support a phylogenetically ancient origin of the orb web, and diversification analyses show that the mostly ground-dwelling, web-less RTA clade diversified faster than orb weavers. Consistent with molecular dating estimates we report herein, this may reflect a major increase in biomass of non-flying insects during the Cretaceous Terrestrial Revolution 125–90 million years ago favoring diversification of spiders that feed on cursorial rather than flying prey. Our results also have major implications for our understanding of spider systematics. Phylogenomic analyses corroborate several well-accepted high level groupings: Opisthothele, Mygalomorphae, Atypoidina, Avicularoidea, Theraphosoidina, Araneomorphae, Entelegynae, Araneoidea, the RTA clade, Dionycha and the Lycosoidea. Alternatively, our results challenge the

  10. Spider phylogenomics: untangling the Spider Tree of Life.

    PubMed

    Garrison, Nicole L; Rodriguez, Juanita; Agnarsson, Ingi; Coddington, Jonathan A; Griswold, Charles E; Hamilton, Christopher A; Hedin, Marshal; Kocot, Kevin M; Ledford, Joel M; Bond, Jason E

    2016-01-01

    Spiders (Order Araneae) are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet and have persisted for over 380 million years. Spiders have long served as evolutionary models for studying complex mating and web spinning behaviors, key innovation and adaptive radiation hypotheses, and have been inspiration for important theories like sexual selection by female choice. Unfortunately, past major attempts to reconstruct spider phylogeny typically employing the "usual suspect" genes have been unable to produce a well-supported phylogenetic framework for the entire order. To further resolve spider evolutionary relationships we have assembled a transcriptome-based data set comprising 70 ingroup spider taxa. Using maximum likelihood and shortcut coalescence-based approaches, we analyze eight data sets, the largest of which contains 3,398 gene regions and 696,652 amino acid sites forming the largest phylogenomic analysis of spider relationships produced to date. Contrary to long held beliefs that the orb web is the crowning achievement of spider evolution, ancestral state reconstructions of web type support a phylogenetically ancient origin of the orb web, and diversification analyses show that the mostly ground-dwelling, web-less RTA clade diversified faster than orb weavers. Consistent with molecular dating estimates we report herein, this may reflect a major increase in biomass of non-flying insects during the Cretaceous Terrestrial Revolution 125-90 million years ago favoring diversification of spiders that feed on cursorial rather than flying prey. Our results also have major implications for our understanding of spider systematics. Phylogenomic analyses corroborate several well-accepted high level groupings: Opisthothele, Mygalomorphae, Atypoidina, Avicularoidea, Theraphosoidina, Araneomorphae, Entelegynae, Araneoidea, the RTA clade, Dionycha and the Lycosoidea. Alternatively, our results challenge the monophyly of

  11. Hey! A Black Widow Spider Bit Me!

    MedlinePlus

    ... a black widow spider, tell an adult immediately . Black widow spider bites rarely kill people, but it's important to get medical attention as ... is. What a Doctor Will Do Doctors treat people who have been bitten by black widow spiders with medications to help relax the ...

  12. A Tank Bromeliad Favors Spider Presence in a Neotropical Inundated Forest.

    PubMed

    Hénaut, Yann; Corbara, Bruno; Pélozuelo, Laurent; Azémar, Frédéric; Céréghino, Régis; Herault, Bruno; Dejean, Alain

    2014-01-01

    Tank bromeliads are good models for understanding how climate change may affect biotic associations. We studied the relationships between spiders, the epiphytic tank bromeliad, Aechmea bracteata, and its associated ants in an inundated forest in Quintana Roo, Mexico, during a drought period while, exceptionally, this forest was dry and then during the flooding that followed. We compared spider abundance and diversity between 'Aechmea-areas' and 'control-areas' of the same surface area. We recorded six spider families: the Dipluridae, Ctenidae, Salticidae, Araneidae, Tetragnathidae and Linyphiidae among which the funnel-web tarantula, Ischnothele caudata, the only Dipluridae noted, was the most abundant. During the drought period, the spiders were more numerous in the Aechmea-areas than in the control-areas, but they were not obligatorily associated with the Aechmea. During the subsequent flooding, the spiders were concentrated in the A. bracteata patches, particularly those sheltering an ant colony. Also, a kind of specificity existed between certain spider taxa and ant species, but varied between the drought period and subsequent flooding. We conclude that climatic events modulate the relationship between A. bracteata patches and their associated fauna. Tank bromeliads, previously considered only for their ecological importance in supplying food and water during drought, may also be considered refuges for spiders during flooding. More generally, tank bromeliads have an important role in preserving non-specialized fauna in inundated forests. PMID:25494055

  13. A Tank Bromeliad Favors Spider Presence in a Neotropical Inundated Forest

    PubMed Central

    Hénaut, Yann; Corbara, Bruno; Pélozuelo, Laurent; Azémar, Frédéric; Céréghino, Régis; Herault, Bruno; Dejean, Alain

    2014-01-01

    Tank bromeliads are good models for understanding how climate change may affect biotic associations. We studied the relationships between spiders, the epiphytic tank bromeliad, Aechmea bracteata, and its associated ants in an inundated forest in Quintana Roo, Mexico, during a drought period while, exceptionally, this forest was dry and then during the flooding that followed. We compared spider abundance and diversity between ‘Aechmea-areas’ and ‘control-areas’ of the same surface area. We recorded six spider families: the Dipluridae, Ctenidae, Salticidae, Araneidae, Tetragnathidae and Linyphiidae among which the funnel-web tarantula, Ischnothele caudata, the only Dipluridae noted, was the most abundant. During the drought period, the spiders were more numerous in the Aechmea-areas than in the control-areas, but they were not obligatorily associated with the Aechmea. During the subsequent flooding, the spiders were concentrated in the A. bracteata patches, particularly those sheltering an ant colony. Also, a kind of specificity existed between certain spider taxa and ant species, but varied between the drought period and subsequent flooding. We conclude that climatic events modulate the relationship between A. bracteata patches and their associated fauna. Tank bromeliads, previously considered only for their ecological importance in supplying food and water during drought, may also be considered refuges for spiders during flooding. More generally, tank bromeliads have an important role in preserving non-specialized fauna in inundated forests. PMID:25494055

  14. Homology, behaviour and spider webs: web construction behaviour of Linyphia hortensis and L. triangularis (Araneae: Linyphiidae) and its evolutionary significance.

    PubMed

    Benjamin, S P; Zschokke, S

    2004-01-01

    Linyphiidae is the second largest family of spiders. Using Linyphia hortensis and L. triangularis, we describe linyphiid sheet-web construction behaviour. Orb-web construction behaviour is reviewed and compared with that of nonorb-weaving orbicularians. Phylogenetic comparisons and the biogenetic law are applied to deduce behavioural homology. Linyphia webs were constructed gradually and in segments over a period of many days and had a long lifespan. Two construction behaviours, supporting structure and sticky thread (ST) (within the sheet) were observed. ST construction behaviour in linyphiids is considered homologous to sticky spiral construction in orb-weavers. Overall web construction conformed to the pattern of alternate construction of sticky and nonsticky parts as observed in theridiids. Linyphiids had no problem in switching between structure construction and ST construction even during a single behavioural bout. Both web construction behaviours in linyphiids were nonstereotypic, which is unusual in orbicularians. This might be due to the loss of control mechanisms at genetic level, probably by macro mutation. Lack of stereotypic behaviour might have played a substantial role in the origin of the diverse web forms seen in nonorb-weaving orbicularians. This hypothesis is consistent with patterns observed in the orbicularian phylogeny.

  15. A golden-silk spider spins its web

    NASA Technical Reports Server (NTRS)

    1999-01-01

    On the grounds of Kennedy Space Center, a female Golden-Silk Spider repairs its web. During the day spider hands head downward from the underside of the web near the center. Its web may measure two to three feet across and it repairs the webbing each day, replacing half but never the whole web at one time. The center shares a boundary with the Merritt Island National Wildlife Refuge, a 92,000-acre refuge that is a habitat for more than 331 species of birds, 31 mammals, 117 fishes, and 65 amphibians and reptiles. The marshes and open water of the refuge provide wintering areas for 23 species of migratory waterfowl, as well as a year-round home for great blue herons, great egrets, wood storks, cormorants, brown pelicans and other species of marsh and shore birds, as well as a variety of insects.

  16. A golden-silk spider spins its web

    NASA Technical Reports Server (NTRS)

    1999-01-01

    On the grounds of Kennedy Space Center, a female Golden-Silk Spider repairs its web. The female can be identified by its brownish-green abdomen with a white spotted irregular pattern. The golden-silk spider repairs the webbing each day, replacing half but never the whole web at one time. Its web may measure two to three feet across. The center shares a boundary with the Merritt Island National Wildlife Refuge, a 92,000-acre refuge that is a habitat for more than 331 species of birds, 31 mammals, 117 fishes, and 65 amphibians and reptiles. The marshes and open water of the refuge provide wintering areas for 23 species of migratory waterfowl, as well as a year-round home for great blue herons, great egrets, wood storks, cormorants, brown pelicans and other species of marsh and shore birds, as well as a variety of insects.

  17. Stage-based mortality of grassland grasshoppers (Acrididae) from wandering spider (Lycosidae) predation

    NASA Astrophysics Data System (ADS)

    Oedekoven, Mark A.; Joern, Anthony

    1998-12-01

    Mortality rates in insects, including grasshoppers (Acrididae), are often stage- or size-specific. We estimated stage-specific mortality rates for three common grasshopper species from a Nebraska (USA) sandhills grassland ( Ageneotettix deorum, Melanoplus sanguinipes and Phoetaliotes nebrascensis), and partitioned the impact due to wandering spider predation from remaining sources. Survivorship was estimated for multiple developmental stages (3rd instar through adult) under experimental conditions that either prevented or permitted predation from free-living, wandering spiders (primarily Schizocosa species). Total stage-specific mortality, including spider predation, examined over the period of single stages was greatest for the youngest stages (91% for 3rd instar, 73% for 4th instar, 63.5% for 5th instar and 30.4% for adults). For the developmental stages considered and averaged for all species, the contribution to total mortality from spider predation over the 10-d period (approximately the length of a developmental stage) ranged from 17% for 3rd instar nymphs to 23% for 4th and 5th instars, and an undetectable level for adults. While spiders may depress grasshopper numbers, contributions from spider predation to grasshopper population dynamics are uncertain.

  18. Task specialization in two social spiders, Stegodyphus sarasinorum (Eresidae) and Anelosimus eximius (Theridiidae).

    PubMed

    Settepani, V; Grinsted, L; Granfeldt, J; Jensen, J L; Bilde, T

    2013-01-01

    Understanding the social organization of group-living organisms is crucial for the comprehension of the underlying selective mechanisms involved in the evolution of cooperation. Division of labour and caste formation is restricted to eusocial organisms, but behavioural asymmetries and reproductive skew is common in other group-living animals. Permanently, social spiders form highly related groups with reproductive skew and communal brood care. We investigated task differentiation in nonreproductive tasks in two permanently and independently derived social spider species asking the following questions: Do individual spiders vary consistently in their propensity to engage in prey attack? Are individual spiders' propensities to engage in web maintenance behaviour influenced by their previous engagement in prey attack? Interestingly, we found that both species showed some degree of task specialization, but in distinctly different ways: Stegodyphus sarasinorum showed behavioural asymmetries at the individual level, that is, individual spiders that had attacked prey once were more likely to attack prey again, independent of their body size or hunger level. In contrast, Anelosimus eximius showed no individual specialization, but showed differentiation according to instar, where adult and subadult females were more likely to engage in prey attack than were juveniles. We found no evidence for division of labour between prey attack and web maintenance. Different solutions to achieve task differentiation in prey attack for the two species studied here suggest an adaptive value of task specialization in foraging for social spiders.

  19. Comparative morphology of pretarsal scopulae in eleven spider families.

    PubMed

    Wolff, Jonas O; Gorb, Stanislav N

    2012-09-01

    Many wandering spiders bear attachment pads (scopulae) on their tarsi, consisting of hierarchically-branching adhesive setae. Amongst spider families and even species, these show remarkable differences in morphology. Using scanning electron microscopy, the scopula microstructure of sixteen spider species was described, with the focus on pretarsal scopulae (claw tufts). Area and shape of the claw tuft, seta and setule density, as well as seta and spatula dimensions were analysed and compared. Claw tufts of the majority of species studied show a similar gradient in size and shape from anterior to posterior legs: the dimension of pads increases, while setal density decreases. Commonly, there is also a gradient of both the seta and spatula size within the claw tuft: Setae become larger from the proximal to the distal part of the pad, and spatulae size increases in the same direction at the level of individual seta. Often, different hierarchical levels of claw tuft organisation are differently expressed in different species: Species with lower setal density usually have broader setae. Smaller spatula size often implicates higher setule density. Evolutionary and ecological aspects of the scopula origin are discussed.

  20. Molecular phylogeny of moth-specialized spider sub-family Cyrtarachninae, which includes bolas spiders.

    PubMed

    Tanikawa, Akio; Shinkai, Akira; Miyashita, Tadashi

    2014-11-01

    The evolutionary process of the unique web architectures of spiders of the sub-family Cyrtarachninae, which includes the triangular web weaver, bolas spider, and webless spider, is thought to be derived from reduction of orbicular 'spanning-thread webs' resembling ordinal orb webs. A molecular phylogenetic analysis was conducted to explore this hypothesis using orbicular web spiders Cyrtarachne, Paraplectana, Poecilopachys, triangular web spider Pasilobus, bolas spiders Ordgarius and Mastophora, and webless spider Celaenia. The phylogeny inferred from partial sequences of mt-COI, nuclear 18S-rRNA and 28S-rRNA showed that the common ancestor of these spiders diverged into two clades: a spanning-thread web clade and a bolas or webless clade. This finding suggests that the triangular web evolved by reduction of an orbicular spanning web, but that bolas spiders evolved in the early stage, which does not support the gradual web reduction hypothesis.

  1. Resistance status of the carmine spider mite, Tetranychus cinnabarinus and the twospotted spider mite, Tetranychus urticae to selected acaricides on strawberries.

    PubMed

    Bi, Jian-Long; Niu, Zi-Mian; Yu, Lu; Toscano, Nick C

    2016-02-01

    The carmine spider mite, Tetranychus cinnabarinus (Boisduval) and the twospotted spider mite, Tetranychus urticae Koch, are serious pests of strawberries and many other horticultural crops. Control of these pests has been heavily dependent upon chemical acaricides. Objectives of this study were to determine the resistance status of these two pest species to commonly used acaricides on strawberries in a year-round intensive horticultural production region. LC90 of abamectin for adult carmine spider mites was 4% whereas that for adult twospotted spider mites was 24% of the top label rate. LC90s of spiromesifen, etoxazole, hexythiazox and bifenazate were 0.5%, 0.5%, 1.4% and 83% of their respective highest label rates for carmine spider mite eggs, 0.7%, 2.7%, 12.1% and 347% of their respective highest label rates for the nymphs. LC90s of spiromesifen, etoxazole, hexythiazox and bifenazate were 4.6%, 11.1%, 310% and 62% of their respective highest label rates for twospotted spider mite eggs, 3%, 13%, 432,214% and 15% of their respective highest label rates for the nymphs. Our results suggest that T. cinnabarinus have developed resistance to bifenazate and that the T. urticae have developed resistance to hexythiazox. These results strongly emphasize the need to develop resistance management strategies in the region.

  2. Chemical recognition of fruit ripeness in spider monkeys (Ateles geoffroyi)

    PubMed Central

    Nevo, Omer; Orts Garri, Rosa; Hernandez Salazar, Laura Teresa; Schulz, Stefan; Heymann, Eckhard W.; Ayasse, Manfred; Laska, Matthias

    2015-01-01

    Primates are now known to possess well-developed olfactory sensitivity and discrimination capacities that can play a substantial role in many aspects of their interaction with conspecifics and the environment. Several studies have demonstrated that olfactory cues may be useful in fruit selection. Here, using a conditioning paradigm, we show that captive spider monkeys (Ateles geoffroyi) display high olfactory discrimination performance between synthetic odor mixtures mimicking ripe and unripe fruits of two wild, primate-consumed, Neotropical plant species. Further, we show that spider monkeys are able to discriminate the odor of ripe fruits from odors that simulate unripe fruits that become increasingly similar to that of ripe ones. These results suggest that the ability of spider monkeys to identify ripe fruits may not depend on the presence of any individual compound that mark fruit ripeness. Further, the results demonstrate that spider monkeys are able to identify ripe fruits even when the odor signal is accompanied by a substantial degree of noise. PMID:26440380

  3. Raiding parties of male spider monkeys: insights into human warfare?

    PubMed

    Aureli, Filippo; Schaffner, Colleen M; Verpooten, Jan; Slater, Kathryn; Ramos-Fernandez, Gabriel

    2006-12-01

    Raids into neighboring territories may occur for different reasons, including the increase of foraging and mating opportunities directly or indirectly through the killing of neighboring rivals. Lethal raids have been mainly observed in humans and chimpanzees, with raiding males being reported to search purposefully for neighbors. Here we report on the first cases ever witnessed of raiding parties of male spider monkeys, a species expected to show such a behavioral tendency, given its similarity with humans and chimpanzees in critical socio-ecological characteristics, such as fission-fusion social dynamics and male-male bonding. Despite the high degree of arboreality of spider monkeys, all seven witnessed raids involved the males progressing single file on the ground in unusual silence. This is remarkably similar to the behavior of chimpanzees. The circumstances around the raids suggest that factors such as reduced mating opportunities, number of males relative to that in the neighboring community, and the strength of bonds among males could play a role in the timing of such actions. The raids did not appear to be aimed at finding food, whereas there is some indication that they may directly or indirectly increase reproductive opportunities. Although no killing was observed, we cannot exclude the possibility that spider monkey raids may be aimed at harming rivals if a vulnerable individual were encountered. The similarity of spider monkey raids with those of chimpanzees and humans supports the notion that lethal raiding is a convergent response to similar socio-ecological conditions. PMID:16685723

  4. Infanticide by a solitary koinobiont ichneumonid ectoparasitoid of spiders.

    PubMed

    Takasuka, Keizo; Matsumoto, Rikio

    2011-06-01

    When encountering an already parasitized host, a parasitoid's optimal choices (superparasitism, host rejection, host feeding or infanticide) seem to depend on the individual species' life history, because the same choice may have different fitness consequences. We demonstrate infanticide under laboratory conditions by a polysphinctine, Zatypota albicoxa, which is a solitary koinobiont ectoparasitoid of spiders. The female always removed any previously attached egg or larva from the body of the host spider, Parasteatoda tepidariorum, with a rubbing behaviour. She rubbed her ovipositor back and forth toward the undersurface of the attached egg or of the saddle under the attached larva to pry it off and laid an egg after removal. When removing a larva, the infanticidal female engaged exclusively in unfastening the 'saddle' which fastens the larva to the body of the spider. All larvae were removed with the 'saddle' attached to the ventral surface of the body. The female invested more time to remove the medium second and the large penultimate instar larvae than to remove eggs and first instar larvae because of the labour involved in unfastening the saddle. Oviposition with infanticide of the medium second and the penultimate instar larvae imposed more time upon the female than that on an unparasitized host. Removal of any previous occupant in spite of the associated labour costs suggests that infanticide will always be adaptive, no matter the time costs to Z. albicoxa, because so much is invested in attacking the host and because the parasitoid cannot detect whether the spider is already parasitized until she achieves subjugation.

  5. Infanticide by a solitary koinobiont ichneumonid ectoparasitoid of spiders

    NASA Astrophysics Data System (ADS)

    Takasuka, Keizo; Matsumoto, Rikio

    2011-06-01

    When encountering an already parasitized host, a parasitoid's optimal choices (superparasitism, host rejection, host feeding or infanticide) seem to depend on the individual species' life history, because the same choice may have different fitness consequences. We demonstrate infanticide under laboratory conditions by a polysphinctine, Zatypota albicoxa, which is a solitary koinobiont ectoparasitoid of spiders. The female always removed any previously attached egg or larva from the body of the host spider, Parasteatoda tepidariorum, with a rubbing behaviour. She rubbed her ovipositor back and forth toward the undersurface of the attached egg or of the saddle under the attached larva to pry it off and laid an egg after removal. When removing a larva, the infanticidal female engaged exclusively in unfastening the `saddle' which fastens the larva to the body of the spider. All larvae were removed with the `saddle' attached to the ventral surface of the body. The female invested more time to remove the medium second and the large penultimate instar larvae than to remove eggs and first instar larvae because of the labour involved in unfastening the saddle. Oviposition with infanticide of the medium second and the penultimate instar larvae imposed more time upon the female than that on an unparasitized host. Removal of any previous occupant in spite of the associated labour costs suggests that infanticide will always be adaptive, no matter the time costs to Z. albicoxa, because so much is invested in attacking the host and because the parasitoid cannot detect whether the spider is already parasitized until she achieves subjugation.

  6. Vibration Propagation in Spider Webs

    NASA Astrophysics Data System (ADS)

    Hatton, Ross; Otto, Andrew; Elias, Damian

    Due to their poor eyesight, spiders rely on web vibrations for situational awareness. Web-borne vibrations are used to determine the location of prey, predators, and potential mates. The influence of web geometry and composition on web vibrations is important for understanding spider's behavior and ecology. Past studies on web vibrations have experimentally measured the frequency response of web geometries by removing threads from existing webs. The full influence of web structure and tension distribution on vibration transmission; however, has not been addressed in prior work. We have constructed physical artificial webs and computer models to better understand the effect of web structure on vibration transmission. These models provide insight into the propagation of vibrations through the webs, the frequency response of the bare web, and the influence of the spider's mass and stiffness on the vibration transmission patterns. Funded by NSF-1504428.

  7. Body-mass-dependent cost of web-building behavior in an orb weaving spider, Zygiella x-notata.

    PubMed

    Venner, Samuel; Bel-Venner, Marie-Claude; Pasquet, Alain; Leborgne, Raymond

    2003-06-01

    In numerous spider species, reproductive success of adult females has been shown to be positively correlated with their body mass. We suggest, however, that spiders may incur greater foraging costs as their body mass increases due to the numerous and complex locomotor bouts needed to build an orb-web. Such a body-mass-dependent cost should, in turn, affect the web-building decisions of spiders. In the laboratory, we tested the influence of body mass on energetic expenditure (measured as mass loss) during web-building behavior in Zygiella x-notata. Our results showed (1) that energetic costs associated with web-building were closely related to body mass and to web-building activity, and (2) that as their body mass increased, spiders reduced the amount of silk used per web, while their foraging effort simultaneously increased. This work gives new insights into web-building behavior and energy allocation strategies of weaving spiders.

  8. Longer-term effects of selective thinning on carabid beetles and spiders in the Cascade Mountains of southern Oregon

    USGS Publications Warehouse

    Peck, R.; Niwa, C.G.

    2005-01-01

    Within late-successional forests of the Cascade Mountains of southern Oregon, abundances of carabid beetles (Carabidae) and spiders (Araneae) from pitfall traps were compared between stands thinned 16-41 years prior and nearby unthinned stands. Species richness of both taxa were moderate for coniferous forests of this region, with 12 carabid beetle species and >120 spider species collected. No differences in total abundance or species richness were found between stand types for carabid beetles, although abundances of four of the six most common species differed significantly. Pterostichus setosus, the most abundant species collected, was significantly more abundant in unthinned stands, while Omus cazieri, P. lama, and Carabus taedatus were more numerous in thinned stands. In contrast, both total spider abundance and species richness were significantly higher in thinned stands. Hunting spiders within the families Lycosidae and Gnaphosidae, and the funnel web-building Dictynidae were captured more often in thinned stands while sheet web spiders within Linyphiidae and Hahniidae were more abundant in unthinned stands. The forest floor within unthinned stands was structurally more diverse than in thinned stands, but this did not lead to greater overall abundance or diversity of either carabid beetles or spiders.

  9. Review of the Australian wolf spider genus Venator (Araneae, Lycosidae).

    PubMed

    Framenau, Volker W

    2015-09-11

    Species of the Australian wolf spider genus Venator are reviewed including the type species, V. spenceri Hogg, 1900, from south-eastern Australia and V. immansuetus (Simon, 1909) comb. nov., a common species in south-west Western Australia. Venator marginatus Hogg, 1900 is only known from two female specimens and the genital morphology of this species does not conform to the diagnosis of genus as presented here. Therefore V. marginatus is considered incerta sedis. Venator includes medium-sized (9.0-22 mm body length) wolf spiders of overall brownish colouration, and with a black patch covering the anterior three quarters of the venter. They differ from all other wolf spiders in particular by genitalic characters, namely an elevated atrium of the female epigyne that forms a raised edged against the inverted T-shaped median septum. This edge often corresponds to a retrolateral incision on the tegular apophysis of the male pedipalp. The genus is mainly a representative of the Bassian fauna of the Australian continent where it occurs predominantly in dry sclerophyll forests.

  10. Parasitism of Trombidium brevimanum larvae on agrobiont linyphiid spiders from Germany.

    PubMed

    Tomić, Vladimir; Mąkol, Joanna; Stamenković, Srdjan; Büchs, Wolfgang; Prescher, Sabine; Sivčev, Ivan; Graora, Draga; Sivčev, Lazar; Gotlin-Čuljak, Tatjana; Dudić, Boris

    2015-08-01

    An experiment on three differently-managed agricultural fields in Ahlum, Germany, which aimed at establishing the impact of different management systems on the biodiversity of predators and decomposers, yielded a significant number of spiders parasitized by larvae of Trombidium brevimanum (Actinotrichida, Parasitengona, Trombidiidae). Spider data from the whole sampling period (September 2010-July 2012), indicated that ectoparasitic larvae were recorded only on spiders in pitfall traps in the period of June-July 2011. In this period, only eight species of Linyphiidae--out of 42 species assigned to nine spider families recorded from the study area--were parasitized by mites; considerable levels of parasitism were recorded on Erigone atra, E. dentipalpis, and Oedothorax apicatus. The highest prevalence of parasitism was recorded on the organic field for E. atra (29%), while on the integrated and conventional fields significantly fewer parasitized spiders were observed. The preferred attachment sites on the spider host were regions with softer cuticle, especially regions on the carapace and on the abdomen, adjacent to the pedicel.

  11. Resting metabolic rates of two orbweb spiders: a first approach to evolutionary success of ecribellate spiders.

    PubMed

    Kawamoto, Tatiana Hideko; Machado, Fabio de A; Kaneto, Gustavo E; Japyassú, Hilton F

    2011-03-01

    Spiders are considered conservative with regard to their resting metabolic rate, presenting the same allometric relation with body mass as the majority of land-arthropods. Nevertheless, web-building is thought to have a great impact on the energetic metabolism, and any modification that affects this complex behavior is expected to have an impact over the daily energetic budget. We analyzed the possibility of the presence of the cribellum having an effect on the allometric relation between resting metabolic rate and body mass for an ecribellate species (Zosis geniculata) and a cribellate one (Metazygia rogenhoferi), and employed a model selection approach to test if these species had the same allometric relationship as other land-arthropods. Our results show that M. rogenhoferi has a higher resting metabolic rate, while Z. geniculata fitted the allometric prediction for land arthropods. This indicates that the absence of the cribellum is associated with a higher resting metabolic rate, thus explaining the higher promptness to activity found for the ecribellate species. If our result proves to be a general rule among spiders, the radiation of Araneoidea could be connected to a more energy-consuming life style. Thus, we briefly outline an alternative model of diversification of Araneoidea that accounts for this possibility.

  12. [Spider diversity in cultures of Citrus sinensis (Rutaceae) in Corrientes province, Argentina].

    PubMed

    Avalos, Gilberto; Bar, Maria Esther; Oscherov, Elena Beatriz; González, Alda

    2013-09-01

    Spiders are predators that reduce insect pest populations in agroecosystems. In spite that the presence of spider assemblages has been described in different crop plants, no reports have been done for Citrus species in Argentina. We studied the spider community associated with cultures of Citrus sinensis in the province of Corrientes, Argentina, in two plots (AM1 irrigated and AM2 unirrigated) of 0.82 hectares each. Spiders were collected monthly by using pitfall traps, hand capture, agitation of foliage and sieving of soil litter. A total of 7174 specimens were collected (33 families, 44 genera and 200 species/morphospecies). The AM1 recorded 3811 individuals (33 families, 179 species/morphospecies) and AM2 3363 individuals (31 families, 174 species/morphospecies). November, December and January showed the highest abundance in both plots. A total of 70% of collected spiders were juveniles. Eight families were the most abundant and represented 75% of spiders collected in both plots, the largest being Lycosidae. We identified eight guilds in both plots, for which the ground runners resulted the most abundant (AM1 n = 1341, s=39, n=999 AM2, s = 33), followed by orb weavers (AM1 n = 637, s = 36; AM2 n = 552, s = 33), the stalkers (AM1 n = 471, s = 43, AM2 n = 453, s = 47) and the space web-builders (AM1 n = 446, s = 23; AM2 n = 342, s = 25). The analysis of alpha diversity in both plots (AM1H' = 4.161, J' = 0.802; AM2 H' = 4.184, J' = 0.811) showed no significant differences (t = 1.083 p = 0.279). The linear dependences model was the one with the best fit results, where the species observed were more than estimated. Clench model estimated 90.9% of the spiders observed in the unit with irrigation and 90.6% in the unit without irrigation.

  13. Variations in Loxosceles spider venom composition and toxicity contribute to the severity of envenomation.

    PubMed

    de Oliveira, Kátia C; Gonçalves de Andrade, Rute M; Piazza, Roxane M F; Ferreira, Jorge M C; van den Berg, C W; Tambourgi, Denise V

    2005-03-15

    Envenomation by Loxosceles spiders causes two main clinical manifestations: cutaneous and systemic loxoscelism. The factors contributing to the severity of loxoscelism are not fully understood. We have analysed biochemical and toxicity variations in venom of L. laeta and L. intermedia, with the aim to find a correlation with the seriousness of loxoscelism. Differences in expression of proteins, glycoproteins and sphingomyelinase activity were observed between venom from male and female spiders and between venom from the two species. These differences were reflected in the toxicity of the venoms including the capacity to induce complement-dependent haemolysis, dermonecrosis and lethality. Comparative analysis of gender and species, showed that these biological activities were more prominent in venom from female spiders, especially from L. laeta. Antiserum raised against venom from females L. laeta spiders had the highest efficacy in neutralizing venoms of males and females of both species. These results indicate that the severity of loxoscelism depends, at least partially, on the species and sex of the spider and suggest that for accidents involving L. laeta an specific serum therapy is necessary. Furthermore, it emphasizes the efficacy of the antiserum produced against L. laeta female venom in neutralizing Loxosceles venoms from different species and gender.

  14. Evaluation of predatory mite (Acari: Phytoseiidae) releases to suppress spruce spider mites, Oligonychus ununguis (Acari: Tetranychidae), on juniper.

    PubMed

    Shrewsbury, Paula M; Hardin, Mark R

    2003-12-01

    A laboratory trial evaluated four phytoseiid species for their potential as biological control agents of spruce spider mite, Oligonychus ununguis (Jacobi) (Acari: Tetranychidae). An augmentative biological control approach, using the predatory mites Neoseiulus fallacis Garman and Galendromus occidentalis Nesbitt (Acari: Phytoseiidae), was evaluated for reducing pest mite densities and injury, and economic costs on Juniperus chinensis 'Sargentii' A. Henry (Cupressaceae) in an outdoor nursery. Sequential releases of predator species, individually and in combination, were tested and compared with two commonly used miticides, a low-toxicity miticide, horticultural oil, and a conventional miticide, hexythiazox. Timing of treatments was based on grower-determined need, and predator release rates were based on guidelines in literature received from producers of beneficial organisms. Predator releases were more expensive and provided less effective suppression of spruce spider mites, resulting in greater spider mite injury to plants, compared with conventional pesticides. However, spider mite damage to plants did not differ in an economically meaningful way between treatments. Unsatisfactory levels of control seem related to under estimations of actual spider mite abundance based on grower perceptions and the beat sampling technique used to estimate predator release rates. These data suggest that when initial populations of spruce spider mite are high, it is unlikely that sequential releases of predator species, individually or in combination, will suppress spider mite populations. In this trial, augmentative biological control control was 2.5-7 times more expensive than chemical controls.

  15. Tisaniba, a new genus of marpissoid jumping spiders from Borneo (Araneae: Salticidae).

    PubMed

    Zhang, Jun-Xia; Maddison, Wayne P

    2014-01-01

    Six new species of marpissoid jumping spiders from Sarawak, Borneo, are described in the new genus Tisaniba Zhang & Maddison. They are the type species, T. mulu Zhang & Maddison sp. nov., as well as the species T. bijibijan Zhang & Maddison sp. nov., T. dik Zhang & Maddison sp. nov., T. kubah Zhang & Maddison sp. nov., T. selan Zhang & Maddison sp. nov., and T. selasi Zhang & Maddison sp. nov. The spiders are small and brown to black, living in leaf litter in the tropical forest. Phylogenetic analyses based on 28s and 16sND1 genes indicate that they are a distinctive group within the marpissoids. Diagnostic illustrations and photographs of living spiders are provided for all species. PMID:25284396

  16. Coadaptive changes in physiological and biophysical traits related to thermal stress in web spiders

    NASA Astrophysics Data System (ADS)

    Kato, Naoko; Takasago, Makoto; Omasa, Kenji; Miyashita, Tadashi

    2008-12-01

    Web spiders are considered to have expanded their habitats from dim to bright environments during the evolutionary history. Because they are sedentary predators exposed to the sun, they may have developed a suite of adaptive traits to cope with thermal stress. We examined the critical thermal maximum, spectral reflectance of solar energy by the body surface, and surface-volume ratio (SVR) for 11 spider species. Analysis of the four genera having a pair of species inhabiting both bright and dim environments showed that species in bright environments exhibited higher lethal temperatures, but spectral reflectance and SVR did not differ. Independent contrasts using the 11 species indicated that critical thermal maximum was positively correlated with spectral reflectance and spectral reflectance was negatively correlated with SVR. These results suggest that physiological tolerance to high temperatures and a biophysical mechanism to reduce heat gain evolved jointly during the history of habitat expansion in araneoid spiders.

  17. Coadaptive changes in physiological and biophysical traits related to thermal stress in web spiders.

    PubMed

    Kato, Naoko; Takasago, Makoto; Omasa, Kenji; Miyashita, Tadashi

    2008-12-01

    Web spiders are considered to have expanded their habitats from dim to bright environments during the evolutionary history. Because they are sedentary predators exposed to the sun, they may have developed a suite of adaptive traits to cope with thermal stress. We examined the critical thermal maximum, spectral reflectance of solar energy by the body surface, and surface-volume ratio (SVR) for 11 spider species. Analysis of the four genera having a pair of species inhabiting both bright and dim environments showed that species in bright environments exhibited higher lethal temperatures, but spectral reflectance and SVR did not differ. Independent contrasts using the 11 species indicated that critical thermal maximum was positively correlated with spectral reflectance and spectral reflectance was negatively correlated with SVR. These results suggest that physiological tolerance to high temperatures and a biophysical mechanism to reduce heat gain evolved jointly during the history of habitat expansion in araneoid spiders.

  18. One size fits all? Determinants of sperm transfer in a highly dimorphic orb-web spider.

    PubMed

    Assis, B A; Foellmer, M W

    2016-06-01

    The evolutionary significance of widespread hypo-allometric scaling of genital traits in combination with rapid interspecific genital trait divergence has been of key interest to evolutionary biologists for many years and remains poorly understood. Here, we provide a detailed assessment of quantitative genital trait variation in males and females of the sexually highly dimorphic and cannibalistic orb-weaving spider Argiope aurantia. We then test how this trait variation relates to sperm transfer success. In particular, we test specific predictions of the one-size-fits-all and lock-and-key hypotheses for the evolution of genital characters. We use video-taped staged matings in a controlled environment with subsequent morphological microdissections and sperm count analyses. We find little support for the prediction of the one-size-fits-all hypothesis for the evolution of hypo-allometric scaling of genital traits, namely that intermediate trait dimensions confer highest sperm transfer success. Likewise, our findings do not support the prediction of the lock-and-key hypothesis that a tight fit of male and female genital traits mediates highest sperm transfer success. We do, however, detect directional effects of a number of male and female genital characters on sperm transfer, suggesting that genital trait dimensions are commonly under selection in nature. Importantly, even though females are much larger than males, spermatheca size limits the number of sperm transferred, contradicting a previous hypothesis about the evolutionary consequences of genital size dimorphism in extremely size-dimorphic taxa. We also find strong positive effects of male body size and copulation duration on the probability of sperm transfer and the number of sperm transferred, with implications for the evolution of extreme sexual size dimorphism and sexual cannibalism in orb weavers. PMID:26881910

  19. One size fits all? Determinants of sperm transfer in a highly dimorphic orb-web spider.

    PubMed

    Assis, B A; Foellmer, M W

    2016-06-01

    The evolutionary significance of widespread hypo-allometric scaling of genital traits in combination with rapid interspecific genital trait divergence has been of key interest to evolutionary biologists for many years and remains poorly understood. Here, we provide a detailed assessment of quantitative genital trait variation in males and females of the sexually highly dimorphic and cannibalistic orb-weaving spider Argiope aurantia. We then test how this trait variation relates to sperm transfer success. In particular, we test specific predictions of the one-size-fits-all and lock-and-key hypotheses for the evolution of genital characters. We use video-taped staged matings in a controlled environment with subsequent morphological microdissections and sperm count analyses. We find little support for the prediction of the one-size-fits-all hypothesis for the evolution of hypo-allometric scaling of genital traits, namely that intermediate trait dimensions confer highest sperm transfer success. Likewise, our findings do not support the prediction of the lock-and-key hypothesis that a tight fit of male and female genital traits mediates highest sperm transfer success. We do, however, detect directional effects of a number of male and female genital characters on sperm transfer, suggesting that genital trait dimensions are commonly under selection in nature. Importantly, even though females are much larger than males, spermatheca size limits the number of sperm transferred, contradicting a previous hypothesis about the evolutionary consequences of genital size dimorphism in extremely size-dimorphic taxa. We also find strong positive effects of male body size and copulation duration on the probability of sperm transfer and the number of sperm transferred, with implications for the evolution of extreme sexual size dimorphism and sexual cannibalism in orb weavers.

  20. The Spider and the Fly

    ERIC Educational Resources Information Center

    Mellinger, Keith E.; Viglione, Raymond

    2012-01-01

    The Spider and the Fly puzzle, originally attributed to the great puzzler Henry Ernest Dudeney, and now over 100 years old, asks for the shortest path between two points on a particular square prism. We explore a generalization, find that the original solution only holds in certain cases, and suggest how this discovery might be used in the…

  1. A proteomics and transcriptomics investigation of the venom from the barychelid spider Trittame loki (brush-foot trapdoor).

    PubMed

    Undheim, Eivind A B; Sunagar, Kartik; Herzig, Volker; Kely, Laurence; Low, Dolyce H W; Jackson, Timothy N W; Jones, Alun; Kurniawan, Nyoman; King, Glenn F; Ali, Syed A; Antunes, Agostino; Ruder, Tim; Fry, Bryan G

    2013-12-13

    Although known for their potent venom and ability to prey upon both invertebrate and vertebrate species, the Barychelidae spider family has been entirely neglected by toxinologists. In striking contrast, the sister family Theraphosidae (commonly known as tarantulas), which last shared a most recent common ancestor with Barychelidae over 200 million years ago, has received much attention, accounting for 25% of all the described spider toxins while representing only 2% of all spider species. In this study, we evaluated for the first time the venom arsenal of a barychelid spider, Trittame loki, using transcriptomic, proteomic, and bioinformatic methods. The venom was revealed to be dominated by extremely diverse inhibitor cystine knot (ICK)/knottin peptides, accounting for 42 of the 46 full-length toxin precursors recovered in the transcriptomic sequencing. In addition to documenting differential rates of evolution adopted by different ICK/knottin toxin lineages, we discovered homologues with completely novel cysteine skeletal architecture. Moreover, acetylcholinesterase and neprilysin were revealed for the first time as part of the spider-venom arsenal and CAP (CRiSP/Allergen/PR-1) were identified for the first time in mygalomorph spider venoms. These results not only highlight the extent of venom diversification in this neglected ancient spider lineage, but also reinforce the idea that unique venomous lineages are rich pools of novel biomolecules that may have significant applied uses as therapeutics and/or insecticides.

  2. Potential lethal and non-lethal effects of predators on dispersal of spider mites.

    PubMed

    Otsuki, Hatsune; Yano, Shuichi

    2014-11-01

    Predators can affect prey dispersal lethally by direct consumption or non-lethally by making prey hesitate to disperse. These lethal and non-lethal effects are detectable only in systems where prey can disperse between multiple patches. However, most studies have drawn their conclusions concerning the ability of predatory mites to suppress spider mites based on observations of their interactions on a single patch or on heavily infested host plants where spider mites could hardly disperse toward intact patches. In these systems, specialist predatory mites that penetrate protective webs produced by spider mites quickly suppress the spider mites, whereas generalist predators that cannot penetrate the webs were ineffective. By using a connected patch system, we revealed that a generalist ant, Pristomyrmex punctatus Mayr (Hymenoptera: Formicidae), effectively prevented dispersal of spider mites, Tetranychus kanzawai Kishida (Acari: Tetranychidae), by directly consuming dispersing individuals. We also revealed that a generalist predatory mite, Euseius sojaensis Ehara (Acari: Phytoseiidae), prevented between-patch dispersal of T. kanzawai by making them hesitate to disperse. In contrast, a specialist phytoseiid predatory mite, Neoseiulus womersleyi Schicha, allowed spider mites to escape an initial patch, increasing the number of colonized patches within the system. Our results suggest that ants and generalist predatory mites can effectively suppress Tetranychus species under some conditions, and should receive more attention as agents for conservation biological control in agroecosystems.

  3. Biomechanical analysis of vertical climbing in the spider monkey and the Japanese macaque.

    PubMed

    Hirasaki, E; Kumakura, H; Matano, S

    2000-12-01

    Climbing is one of the most important components of primate locomotor modes. We previously reported that the kinesiological characteristics of vertical climbing by the spider monkey and Japanese macaque are clearly different, based on their kinetics and kinematics. In this study, a more detailed analysis using inverse dynamics was conducted to estimate the biomechanical characteristics of vertical climbing in the spider monkey and Japanese macaque. One of the main findings was the difference in forelimb use by the two species. The results of a joint moment analysis and estimates of muscular force indicate that the spider monkey uses its forelimbs to keep the body close to the substrate, rather than to generate propulsion. The forelimb of the Japanese macaque, on the other hand, likely contributes more to propulsion. This supports the idea that "forelimb-hindlimb differentiation" is promoted in the spider monkey. The estimated muscular force also suggests that the spider monkey type of climbing could develop the hindlimb extensor muscles, which are important in bipedal posture and walking. As a result, we conclude that the spider monkey type of climbing could be functionally preadaptive for human bipedalism. This type of climbing would develop the hip and knee extensor muscles, and result in more extended lower limb joints, a more erect trunk posture, and more functionally differentiated fore- and hindlimbs, all of which are important characteristics of human bipedalism.

  4. Specialised use of working memory by Portia africana, a spider-eating salticid.

    PubMed

    Cross, Fiona R; Jackson, Robert R

    2014-03-01

    Using expectancy-violation methods, we investigated the role of working memory in the predatory strategy of Portia africana, a salticid spider from Kenya that preys by preference on other spiders. One of this predator's tactics is to launch opportunistic leaping attacks on to other spiders in their webs. Focussing on this particular tactic, our experiments began with a test spider on a ramp facing a lure (dead prey spider mounted on a cork disc) that could be reached by leaping. After the test spider faced the lure for 30 s, we blocked the test spider's view of the lure by lowering an opaque shutter before the spider leapt. When the shutter was raised 90 s later, either the same lure came into view again (control) or a different lure came into view (experimental: different prey type in same orientation or same prey type in different orientation). We recorded attack frequency (number of test spiders that leapt at the lure) and attack latency (time elapsing between shutter being raised and spiders initiating a leap). Attack latencies in control trials were not significantly different from attack latencies in experimental trials, regardless of whether it was prey type or prey orientation that changed in the experimental trials. However, compared with test spiders in the no-change control trials, significantly fewer test spiders leapt when prey type changed. There was no significant effect on attack frequency when prey orientation changed. These findings suggest that this predator represents prey type independently of prey orientation.

  5. Multi-modal courtship in the peacock spider, Maratus volans (O.P.-Cambridge, 1874).

    PubMed

    Girard, Madeline B; Kasumovic, Michael M; Elias, Damian O

    2011-01-01

    The peacock spider, Maratus volans, has one of the most elaborate courtship displays in arthropods. Using regular and high-speed video segments captured in the lab, we provide detailed descriptions of complete male courtship dances. As research on jumping spiders has demonstrated that males of some species produce vibrations concurrently with visual displays, we also used laser vibrometry to uncover such elements for this species. Our recordings reveal and describe for the first time, that M. volans males use vibratory signals in addition to complex body ornaments and motion displays. The peacock spider and other closely related species are outstanding study organisms for testing hypotheses about the evolution and functional significance of complex displays, thus, this descriptive study establishes a new model system for behavioral ecology, one that certainly stands to make important contributions to the field. PMID:21980440

  6. Multi-Modal Courtship in the Peacock Spider, Maratus volans (O.P.-Cambridge, 1874)

    PubMed Central

    Girard, Madeline B.; Kasumovic, Michael M.; Elias, Damian O.

    2011-01-01

    The peacock spider, Maratus volans, has one of the most elaborate courtship displays in arthropods. Using regular and high-speed video segments captured in the lab, we provide detailed descriptions of complete male courtship dances. As research on jumping spiders has demonstrated that males of some species produce vibrations concurrently with visual displays, we also used laser vibrometry to uncover such elements for this species. Our recordings reveal and describe for the first time, that M. volans males use vibratory signals in addition to complex body ornaments and motion displays. The peacock spider and other closely related species are outstanding study organisms for testing hypotheses about the evolution and functional significance of complex displays, thus, this descriptive study establishes a new model system for behavioral ecology, one that certainly stands to make important contributions to the field. PMID:21980440

  7. Milking and partial characterization of venom from the Brazilian spider Vitalius dubius (Theraphosidae).

    PubMed

    Rocha-E-Silva, Thomaz A A; Sutti, Rafael; Hyslop, Stephen

    2009-01-01

    The theraphosid spider genus Vitalius contains several species found in southeastern Brazil. In this work, we used electrostimulation to obtain venom from Vitalius dubius and examined its general composition. Male spiders yielded significantly less (p < 0.05) venom (12.5 +/- 0.7 mg of liquid/spider, n = 16; mean +/- S.E.M.) than female spiders (25.5 +/- 2.0 mg of liquid/spider, n = 11). However, when corrected for spider weight, males yielded slightly more venom (2.89 +/- 0.16 mg/g vs. 2.45 +/- 0.76 mg/g for males and females, respectively, p < 0.05). Venom yield correlated linearly with spider weight for spiders weighing up to approximately 12-13 g, but decreased in very heavy females. There was a marked decrease in venom yield after the first milking. The protein concentration of pooled venom was 18.3 +/- 2.4 mg/ml (n = 4) and accounted for 16.6 +/- 4.7% of the dry venom weight. The venom contained high hyaluronidase activity (275 +/- 24 TRU/mg of protein, n = 4), with a molecular mass of approximately 45 kDa estimated by zymography. SDS-PAGE revealed a few proteins with molecular masses >14 kDa but showed two staining bands of peptides <14 kDa. The venom reacted in ELISA with affinity-purified IgG from commercial arachnidic antivenom. Immunoblotting with this IgG detected proteins of 30-140 kDa only. Fractionation of the venom by reverse-phase chromatography resulted in five major and eight minor peaks.

  8. Carbon nanotubes on a spider silk scaffold

    PubMed Central

    Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

    2013-01-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations. PMID:24022336

  9. Spider: Searching for the Echos of Inflation

    NASA Astrophysics Data System (ADS)

    Jones, William C.; Observational Cosmology Group

    2006-12-01

    Spider is a balloon-borne scientific and technical pathfinder for CMBpol. Spider will map over half the sky with degree angular resolution, characterizing the linear polarization in five bands between 70 and 300 GHz, to a depth greater than Planck. The Spider data will complement the WMAP data (<100 GHz) in frequency coverage, and the data from Planck in polarimetric fidelity, significantly enhancing the scientific value of each of these orbital missions. The Spider flight will test receiver technology, optics, and an observing strategy that are directly applicable to CMBpol.

  10. Carbon nanotubes on a spider silk scaffold.

    PubMed

    Steven, Eden; Saleh, Wasan R; Lebedev, Victor; Acquah, Steve F A; Laukhin, Vladimir; Alamo, Rufina G; Brooks, James S

    2013-01-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations.

  11. Carbon nanotubes on a spider silk scaffold

    NASA Astrophysics Data System (ADS)

    Steven, Eden; Saleh, Wasan R.; Lebedev, Victor; Acquah, Steve F. A.; Laukhin, Vladimir; Alamo, Rufina G.; Brooks, James S.

    2013-09-01

    Understanding the compatibility between spider silk and conducting materials is essential to advance the use of spider silk in electronic applications. Spider silk is tough, but becomes soft when exposed to water. Here we report a strong affinity of amine-functionalised multi-walled carbon nanotubes for spider silk, with coating assisted by a water and mechanical shear method. The nanotubes adhere uniformly and bond to the silk fibre surface to produce tough, custom-shaped, flexible and electrically conducting fibres after drying and contraction. The conductivity of coated silk fibres is reversibly sensitive to strain and humidity, leading to proof-of-concept sensor and actuator demonstrations.

  12. Post-secretion processing influences spider silk performance

    PubMed Central

    Blamires, Sean J.; Wu, Chung-Lin; Blackledge, Todd A.; Tso, I-Min

    2012-01-01

    Phenotypic variation facilitates adaptations to novel environments. Silk is an example of a highly variable biomaterial. The two-spidroin (MaSp) model suggests that spider major ampullate (MA) silk is composed of two proteins—MaSp1 predominately contains alanine and glycine and forms strength enhancing β-sheet crystals, while MaSp2 contains proline and forms elastic spirals. Nonetheless, mechanical properties can vary in spider silks without congruent amino acid compositional changes. We predicted that post-secretion processing causes variation in the mechanical performance of wild MA silk independent of protein composition or spinning speed across 10 species of spider. We used supercontraction to remove post-secretion effects and compared the mechanics of silk in this ‘ground state’ with wild native silks. Native silk mechanics varied less among species compared with ‘ground state’ silks. Variability in the mechanics of ‘ground state’ silks was associated with proline composition. However, variability in native silks did not. We attribute interspecific similarities in the mechanical properties of native silks, regardless of amino acid compositions, to glandular processes altering molecular alignment of the proteins prior to extrusion. Such post-secretion processing may enable MA silk to maintain functionality across environments, facilitating its function as a component of an insect-catching web. PMID:22628213

  13. Comparing the rheology of native spider and silkworm spinning dope

    NASA Astrophysics Data System (ADS)

    Holland, C.; Terry, A. E.; Porter, D.; Vollrath, F.

    2006-11-01

    Silk production has evolved to be energetically efficient and functionally optimized, yielding a material that can outperform most industrial fibres, particularly in toughness. Spider silk has hitherto defied all attempts at reproduction, despite advances in our understanding of the molecular mechanisms behind its superb mechanical properties. Spun fibres, natural and man-made, rely on the extrusion process to facilitate molecular orientation and bonding. Hence a full understanding of the flow characteristics of native spinning feedstock (dope) will be essential to translate natural spinning to artificial silk production. Here we show remarkable similarity between the rheologies for native spider-dragline and silkworm-cocoon silk, despite their independent evolution and substantial differences in protein structure. Surprisingly, both dopes behave like typical polymer melts. This observation opens the door to using polymer theory to clarify our general understanding of natural silks, despite the many specializations found in different animal species.

  14. The age and evolution of sociality in Stegodyphus spiders: a molecular phylogenetic perspective.

    PubMed

    Johannesen, Jes; Lubin, Yael; Smith, Deborah R; Bilde, Trine; Schneider, Jutta M

    2007-01-22

    Social, cooperative breeding behaviour is rare in spiders and generally characterized by inbreeding, skewed sex ratios and high rates of colony turnover, processes that when combined may reduce genetic variation and lower individual fitness quickly. On these grounds, social spider species have been suggested to be unstable in evolutionary time, and hence sociality a rare phenomenon in spiders. Based on a partial molecular phylogeny of the genus Stegodyphus, we address the hypothesis that social spiders in this genus are evolutionary transient. We estimate the age of the three social species, test whether they represent an ancestral or derived state and assess diversification relative to subsocial congeners. Intraspecific sequence divergence was high in all of the social species, lending no support for the idea that they are young, transient species. The age of the social lineages, constant lineage branching and the likelihood that social species are independently derived suggest that either the social species are 'caught in sociality' or they have evolved into cryptic species. PMID:17148252

  15. Spider diversity (Arachnida: Araneae) in Atlantic Forest areas at Pedra Branca State Park, Rio de Janeiro, Brazil

    PubMed Central

    Pérez-González, Abel; Baptista, Renner L. C.

    2016-01-01

    Abstract Background There has never been any published work about the diversity of spiders in the city of Rio de Janeiro using analytical tools to measure diversity. The only available records for spider communities in nearby areas indicate 308 species in the National Park of Tijuca and 159 species in Marapendi Municipal Park. These numbers are based on a rapid survey and on an one-year survey respectively. New information This study provides a more thorough understanding of how the spider species are distributed at Pedra Branca State Park. We report a total of 14,626 spider specimens recorded from this park, representing 49 families and 373 species or morphospecies, including at least 73 undescribed species. Also, the distribution range of 45 species was expanded, and species accumulation curves estimate that there is a minimum of 388 (Bootstrap) and a maximum of 468 species (Jackknife2) for the sampled areas. These estimates indicates that the spider diversity may be higher than observed. PMID:26929710

  16. A comparative analysis of the morphology and evolution of permanent sperm depletion in spiders.

    PubMed

    Michalik, Peter; Rittschof, Clare C

    2011-01-11

    Once thought to be energetically cheap and easy to produce, empirical work has shown that sperm is a costly and limited resource for males. In some spider species, there is behavioral evidence that sperm are permanently depleted after a single mating. This extreme degree of mating investment appears to co-occur with other reproductive strategies common to spiders, e.g. genital mutilation and sexual cannibalism. Here we corroborate that sperm depletion in the golden orb-web spider Nephila clavipes is permanent by uncovering its mechanistic basis using light and electron microscopy. In addition, we use a phylogeny-based statistical analysis to test the evolutionary relationships between permanent sperm depletion (PSD) and other reproductive strategies in spiders. Male testes do not produce sperm during adulthood, which is unusual in spiders. Instead, spermatogenesis is nearly synchronous and ends before the maturation molt. Testis size decreases as males approach their maturation molt and reaches its lowest point after sperm is transferred into the male copulatory organs (pedipalps). As a consequence, the amount of sperm available to males for mating is limited to the sperm contained in the pedipalps, and once it is used, males lose their ability to fertilize eggs. Our data suggest that PSD has evolved independently at least three times within web-building spiders and is significantly correlated with the evolution of other mating strategies that limit males to monogamy, including genital mutilation and sexual cannibalism. We conclude that PSD may be an energy-saving adaptation in species where males are limited to monogamy. This could be particularly important in web-building spiders where extreme sexual size dimorphism results in large, sedentary females and small, searching males who rarely feed as adults and are vulnerable to starvation. Future work will explore possible energetic benefits and the evolutionary lability of PSD relative to other mate

  17. Predator-Prey Interactions are Context Dependent in a Grassland Plant-Grasshopper-Wolf Spider Food Chain.

    PubMed

    Laws, Angela N; Joern, Anthony

    2015-06-01

    Species interactions are often context dependent, where outcomes vary in response to one or more environmental factors. It remains unclear how abiotic conditions like temperature combine with biotic factors such as consumer density or food quality to affect resource availability or influence species interactions. Using the large grasshopper Melanoplus bivittatus (Say) and a common wolf spider [Rabidosa rabida (Walkenaer)], we conducted manipulative field experiments in tallgrass prairie to examine how spider-grasshopper interactions respond to manipulations of temperature, grasshopper density, and food quality. Grasshopper survival was density dependent, as were the effects of spider presence and food quality in context-dependent ways. In high grasshopper density treatments, predation resulted in increased grasshopper survival, likely as a result of reduced intraspecific competition in the presence of spiders. Spiders had no effect on grasshopper survival when grasshoppers were stocked at low densities. Effects of the experimental treatments were often interdependent so that effects were only observed when examined together with other treatments. The occurrence of trophic cascades was context dependent, where the effects of food quality and spider presence varied with temperature under high-density treatments. Temperature weakly affected the impact of spider presence on M. bivittatus survivorship when all treatments were considered simultaneously, but different context-dependent responses to spider presence and food quality were observed among the three temperature treatments under high-density conditions. Our results indicate that context-dependent species interactions are common and highlight the importance of understanding how key biotic and abiotic factors combine to influence species interactions. PMID:26313957

  18. Predator-Prey Interactions are Context Dependent in a Grassland Plant-Grasshopper-Wolf Spider Food Chain.

    PubMed

    Laws, Angela N; Joern, Anthony

    2015-06-01

    Species interactions are often context dependent, where outcomes vary in response to one or more environmental factors. It remains unclear how abiotic conditions like temperature combine with biotic factors such as consumer density or food quality to affect resource availability or influence species interactions. Using the large grasshopper Melanoplus bivittatus (Say) and a common wolf spider [Rabidosa rabida (Walkenaer)], we conducted manipulative field experiments in tallgrass prairie to examine how spider-grasshopper interactions respond to manipulations of temperature, grasshopper density, and food quality. Grasshopper survival was density dependent, as were the effects of spider presence and food quality in context-dependent ways. In high grasshopper density treatments, predation resulted in increased grasshopper survival, likely as a result of reduced intraspecific competition in the presence of spiders. Spiders had no effect on grasshopper survival when grasshoppers were stocked at low densities. Effects of the experimental treatments were often interdependent so that effects were only observed when examined together with other treatments. The occurrence of trophic cascades was context dependent, where the effects of food quality and spider presence varied with temperature under high-density treatments. Temperature weakly affected the impact of spider presence on M. bivittatus survivorship when all treatments were considered simultaneously, but different context-dependent responses to spider presence and food quality were observed among the three temperature treatments under high-density conditions. Our results indicate that context-dependent species interactions are common and highlight the importance of understanding how key biotic and abiotic factors combine to influence species interactions.

  19. Influence of Crop Management and Environmental Factors on Wolf Spider Assemblages (Araneae: Lycosidae) in an Australian Cotton Cropping System.

    PubMed

    Rendon, Dalila; Whitehouse, Mary E A; Hulugalle, Nilantha R; Taylor, Phillip W

    2015-02-01

    Wolf spiders (Lycosidae) are the most abundant ground-hunting spiders in the Australian cotton (Gossypium hirsutum L.) agroecosystems. These spiders have potential in controlling pest bollworms, Helicoverpa spp. (Lepidoptera: Noctuidae) in minimum-tilled fields. A study was carried out during a wet growing season (2011-2012) in Narrabri, New South Wales, Australia, to determine how different crop rotations and tillage affect wolf spider assemblages in cotton fields. Spider abundance and species richness did not differ significantly between simple plots (no winter crop) and complex plots (cotton-wheat Triticum aestivum L.-vetch Vicia benghalensis L. rotation). However, the wolf spider biodiversity, as expressed by the Shannon-Weaver and Simpson's indices, was significantly higher in complex plots. Higher biodiversity reflected a more even distribution of the most dominant species (Venatrix konei Berland, Hogna crispipes Koch, and Tasmanicosa leuckartii Thorell) and the presence of more rare species in complex plots. T. leuckartii was more abundant in complex plots and appears to be sensitive to farming disturbances, whereas V. konei and H. crispipes were similarly abundant in the two plot types, suggesting higher resilience or recolonizing abilities. The demographic structure of these three species varied through the season, but not between plot types. Environmental variables had a significant effect on spider assemblage, but effects of environment and plot treatment were overshadowed by the seasonal progression of cotton stages. Maintaining a high density and even distribution of wolf spiders that prey on Helicoverpa spp. should be considered as a conservation biological control element when implementing agronomic and pest management strategies.

  20. Influence of Crop Management and Environmental Factors on Wolf Spider Assemblages (Araneae: Lycosidae) in an Australian Cotton Cropping System.

    PubMed

    Rendon, Dalila; Whitehouse, Mary E A; Hulugalle, Nilantha R; Taylor, Phillip W

    2015-02-01

    Wolf spiders (Lycosidae) are the most abundant ground-hunting spiders in the Australian cotton (Gossypium hirsutum L.) agroecosystems. These spiders have potential in controlling pest bollworms, Helicoverpa spp. (Lepidoptera: Noctuidae) in minimum-tilled fields. A study was carried out during a wet growing season (2011-2012) in Narrabri, New South Wales, Australia, to determine how different crop rotations and tillage affect wolf spider assemblages in cotton fields. Spider abundance and species richness did not differ significantly between simple plots (no winter crop) and complex plots (cotton-wheat Triticum aestivum L.-vetch Vicia benghalensis L. rotation). However, the wolf spider biodiversity, as expressed by the Shannon-Weaver and Simpson's indices, was significantly higher in complex plots. Higher biodiversity reflected a more even distribution of the most dominant species (Venatrix konei Berland, Hogna crispipes Koch, and Tasmanicosa leuckartii Thorell) and the presence of more rare species in complex plots. T. leuckartii was more abundant in complex plots and appears to be sensitive to farming disturbances, whereas V. konei and H. crispipes were similarly abundant in the two plot types, suggesting higher resilience or recolonizing abilities. The demographic structure of these three species varied through the season, but not between plot types. Environmental variables had a significant effect on spider assemblage, but effects of environment and plot treatment were overshadowed by the seasonal progression of cotton stages. Maintaining a high density and even distribution of wolf spiders that prey on Helicoverpa spp. should be considered as a conservation biological control element when implementing agronomic and pest management strategies. PMID:26308820

  1. Novel Class of Spider Toxin

    PubMed Central

    Vassilevski, Alexander A.; Fedorova, Irina M.; Maleeva, Ekaterina E.; Korolkova, Yuliya V.; Efimova, Svetlana S.; Samsonova, Olga V.; Schagina, Ludmila V.; Feofanov, Alexei V.; Magazanik, Lev G.; Grishin, Eugene V.

    2010-01-01

    Venom of the yellow sac spider Cheiracanthium punctorium (Miturgidae) was found unique in terms of molecular composition. Its principal toxic component CpTx 1 (15.1 kDa) was purified, and its full amino acid sequence (134 residues) was established by protein chemistry and mass spectrometry techniques. CpTx 1 represents a novel class of spider toxin with modular architecture. It consists of two different yet homologous domains (modules) each containing a putative inhibitor cystine knot motif, characteristic of the widespread single domain spider neurotoxins. Venom gland cDNA sequencing provided precursor protein (prepropeptide) structures of three CpTx 1 isoforms (a–c) that differ by single residue substitutions. The toxin possesses potent insecticidal (paralytic and lethal), cytotoxic, and membrane-damaging activities. In both fly and frog neuromuscular preparations, it causes stable and irreversible depolarization of muscle fibers leading to contracture. This effect appears to be receptor-independent and is inhibited by high concentrations of divalent cations. CpTx 1 lyses cell membranes, as visualized by confocal microscopy, and destabilizes artificial membranes in a manner reminiscent of other membrane-active peptides by causing numerous defects of variable conductance and leading to bilayer rupture. The newly discovered class of modular polypeptides enhances our knowledge of the toxin universe. PMID:20657014

  2. Science Education Resources on the Web--Spiders.

    ERIC Educational Resources Information Center

    Thirunarayanan, M. O.

    1997-01-01

    Lists Web sites containing information on spiders and offers brief descriptions of the information available at those sites. The 11 sites provide information on taxonomy of spiders, anatomy, different ways spiders use silk, Internet mailing lists, folk literature and art, bibliographies, night collection, and spiders commonly found in the state of…

  3. Tracking a medically important spider: climate change, ecological niche modeling, and the brown recluse (Loxosceles reclusa).

    PubMed

    Saupe, Erin E; Papes, Monica; Selden, Paul A; Vetter, Richard S

    2011-01-01

    Most spiders use venom to paralyze their prey and are commonly feared for their potential to cause injury to humans. In North America, one species in particular, Loxosceles reclusa (brown recluse spider, Sicariidae), causes the majority of necrotic wounds induced by the Araneae. However, its distributional limitations are poorly understood and, as a result, medical professionals routinely misdiagnose brown recluse bites outside endemic areas, confusing putative spider bites for other serious conditions. To address the issue of brown recluse distribution, we employ ecological niche modeling to investigate the present and future distributional potential of this species. We delineate range boundaries and demonstrate that under future climate change scenarios, the spider's distribution may expand northward, invading previously unaffected regions of the USA. At present, the spider's range is centered in the USA, from Kansas east to Kentucky and from southern Iowa south to Louisiana. Newly influenced areas may include parts of Nebraska, Minnesota, Wisconsin, Michigan, South Dakota, Ohio, and Pennsylvania. These results illustrate a potential negative consequence of climate change on humans and will aid medical professionals in proper bite identification/treatment, potentially reducing bite misdiagnoses. PMID:21464985

  4. [Diversity of insects captured by weaver spiders (Arachnida: Araneae) in the cocoa agroecosystem in Tabasco, Mexico].

    PubMed

    Pérez-de La Cruz, Manuel; Sánchez-Soto, Saúl; Ortíz-García, Carlos F; Zapata-Mata, Raúl; Cruz-Pérez, Aracely de la

    2007-01-01

    The aim of this work was to know the diversity of insects captured by weaver spiders in a plantation of cocoa (Theobroma cacao L.) of 6 ha in the State of Tabasco, Mexico. The study was carried out from July 2004 to June 2005 by means biweekly samples of the insects captured on the spiders webs. The total of 3,041 webs of 54 species of spiders belonging to seven families (Araneidae, Theridiidae, Tetragnathidae, Uloboridae, Pholcidae, Dyctinidae and Linyphiidae) were revised. We found 1,749 specimens belonging to 10 orders of insects, represented by 93 families, the majority of Coleoptera, Diptera and Hemiptera that constituted 74% of the identified families. The biggest number of specimens of all orders was captured by Araneidae, except of Isoptera, whose specimens were captured mainly by the family Theridiidae. The index of diversity (H'), evenness (J') and similarity (Is), applied to know the diversity of families of insects captured among families of spiders, varied from 0.00 to 3.24, 0.00 to 0.81, and 0.04 to 0.522, respectively. We conclude that there is a wide diversity of insects predated by the weaver spiders in the cocoa agroecosystem, and that there are species that can be promising for the biological control of pests.

  5. The reproductive potential of the spiders Agelena labyrinthica and Xerolycosa nemoralis from areas contaminated with metals.

    PubMed

    Babczyńska, Agnieszka; Wilczek, Grażyna; Szulińska, Elżbieta; Kędziorski, Andrzej; Franiel, Izabella; Migula, Paweł

    2012-10-01

    Spiders successfully colonize industrially contaminated environments and maintain relatively stable populations. The aim of this study was to explain the reproductive strategies of two spider species, Xerolycosa nemoralis (an actively hunting, sit-and-pursue predator) and Agelena labyrinthica (a web-building, sit-and-wait predator), between contaminated and uncontaminated sites. Spiders were collected from a reference site (Pilica) and two contaminated sites (Olkusz and Welnowiec). The amount of energy allocated to the eggs and the number of eggs and hatchlings as well as the hatching success were compared. Wolf spiders from the contaminated sites produced fewer but relatively energy-rich eggs, whereas web-building spiders invested their energy in the production of a higher number of less energy-rich eggs. The comparisons of the hatching percentages suggested that in the contaminated habitats, X. nemoralis achieve a hatching success similar to or higher than that of the reference population at Pilica. A. labyrinthica in the contaminated sites invested a larger amount of energy in eggs than at the reference site, but the hatching success found for this species in the contaminated areas was lower than that found at the reference site.

  6. Antipredator behaviours of a spider mite in response to cues of dangerous and harmless predators.

    PubMed

    Dias, Cleide Rosa; Bernardo, Ana Maria Guimarães; Mencalha, Jussara; Freitas, Caelum Woods Carvalho; Sarmento, Renato Almeida; Pallini, Angelo; Janssen, Arne

    2016-07-01

    Prey are known to invest in costly antipredator behaviour when perceiving cues of dangerous, but not of relatively harmless predators. Whereas most studies investigate one type of antipredator behaviour, we studied several types (changes in oviposition, in escape and avoidance behaviour) in the spider mite Tetranychus evansi in response to cues from two predatory mites. The predator Phytoseiulus longipes is considered a dangerous predator for T. evansi, whereas Phytoseiulus macropilis has a low predation rate on this prey, thus is a much less dangerous predator. Spider mite females oviposited less on leaf disc halves with predator cues than on clean disc halves, independent of the predator species. On entire leaf discs, they laid fewer eggs in the presence of cues of the dangerous predator than on clean discs, but not in the presence of cues of the harmless predator. Furthermore, the spider mites escaped more often from discs with cues of the dangerous predator than from discs without predator cues, but they did not escape more from discs with cues of the harmless predator. The spider mites did not avoid plants with conspecifics and predators. We conclude that the spider mites displayed several different antipredator responses to the same predator species, and that some of these antipredator responses were stronger with cues of dangerous predators than with cues of harmless predators. PMID:27067101

  7. Antipredator behaviours of a spider mite in response to cues of dangerous and harmless predators.

    PubMed

    Dias, Cleide Rosa; Bernardo, Ana Maria Guimarães; Mencalha, Jussara; Freitas, Caelum Woods Carvalho; Sarmento, Renato Almeida; Pallini, Angelo; Janssen, Arne

    2016-07-01

    Prey are known to invest in costly antipredator behaviour when perceiving cues of dangerous, but not of relatively harmless predators. Whereas most studies investigate one type of antipredator behaviour, we studied several types (changes in oviposition, in escape and avoidance behaviour) in the spider mite Tetranychus evansi in response to cues from two predatory mites. The predator Phytoseiulus longipes is considered a dangerous predator for T. evansi, whereas Phytoseiulus macropilis has a low predation rate on this prey, thus is a much less dangerous predator. Spider mite females oviposited less on leaf disc halves with predator cues than on clean disc halves, independent of the predator species. On entire leaf discs, they laid fewer eggs in the presence of cues of the dangerous predator than on clean discs, but not in the presence of cues of the harmless predator. Furthermore, the spider mites escaped more often from discs with cues of the dangerous predator than from discs without predator cues, but they did not escape more from discs with cues of the harmless predator. The spider mites did not avoid plants with conspecifics and predators. We conclude that the spider mites displayed several different antipredator responses to the same predator species, and that some of these antipredator responses were stronger with cues of dangerous predators than with cues of harmless predators.

  8. Tracking a Medically Important Spider: Climate Change, Ecological Niche Modeling, and the Brown Recluse (Loxosceles reclusa)

    PubMed Central

    Saupe, Erin E.; Papes, Monica; Selden, Paul A.; Vetter, Richard S.

    2011-01-01

    Most spiders use venom to paralyze their prey and are commonly feared for their potential to cause injury to humans. In North America, one species in particular, Loxosceles reclusa (brown recluse spider, Sicariidae), causes the majority of necrotic wounds induced by the Araneae. However, its distributional limitations are poorly understood and, as a result, medical professionals routinely misdiagnose brown recluse bites outside endemic areas, confusing putative spider bites for other serious conditions. To address the issue of brown recluse distribution, we employ ecological niche modeling to investigate the present and future distributional potential of this species. We delineate range boundaries and demonstrate that under future climate change scenarios, the spider's distribution may expand northward, invading previously unaffected regions of the USA. At present, the spider's range is centered in the USA, from Kansas east to Kentucky and from southern Iowa south to Louisiana. Newly influenced areas may include parts of Nebraska, Minnesota, Wisconsin, Michigan, South Dakota, Ohio, and Pennsylvania. These results illustrate a potential negative consequence of climate change on humans and will aid medical professionals in proper bite identification/treatment, potentially reducing bite misdiagnoses. PMID:21464985

  9. Immobilizing and lethal effects of spider venoms on the cockroach and the common mealbeetle.

    PubMed

    Friedel, T; Nentwig, W

    1989-01-01

    Immobilizing and lethal effects of the venoms obtained from six spider species (Brachypelma albopilosum, Atrax robustus, Cupiennius salei, Selenops mexicanus, Tegenaria atrica, Argiope bruennichi) were tested on Blatta orientalis (cockroach) and Tenebrio molitor (common mealbeetle). The immobilizing effects were quantified by measuring insect locomotor activity in circle arenas observed over 72 hr after venom injection. Both insect species showed cramps, quivering and jerking of the limbs as well as flaccid paralysis after venom injection. Through relative toxicity of the venoms tested is the same in T. molitor and B. orientalis, T. molitor is absolutely less sensitive to spider venoms. The effects on locomotor activity show time characteristics specific for each venom. A dependence of the venom paralyzing effects on insect locomotor activity, low intensity of the initial excitatory phase of the venom effects and partial recovery of the insects was found with A. bruennichi and T. atrica venom. The maximal venom yields of A. bruennichi and S. mexicanus are not lethal to B. orientalis, indicating that the mere immobilizing effects of spider venoms are far more crucial to prey capture than their lethal effects. The contribution of a variety of differently acting neurotoxic components in spider venoms to the observed venom effects on insects and the significance of the venoms in spider nutrition, hunting behaviour and ecology are discussed. PMID:2728023

  10. Spider management in agroecosystems: Habitat manipulation

    NASA Astrophysics Data System (ADS)

    Mansour, Fadel; Richman, David B.; Whitcomb, W. H.

    1983-01-01

    Based on the literature and on work conducted in Israel, the management of spider populations through habitat manipulation was found to be very helpful in controlling pest insects in various crops. Spiders were found to be reduced or eliminated by non-selective insecticides, although some resistance has been noted

  11. Insects and Spiders. Environmental Education Curriculum.

    ERIC Educational Resources Information Center

    Topeka Public Schools, KS.

    This unit is designed to provide information on insects and spiders that special education students are capable of understanding. The activities are aimed at level 2 and level 3 educable mentally retarded classes. There are four topics: (1) Characteristics and Life Cycles of Insects; (2) Characteristics of Spiders; (3) Habitats and Food Sources of…

  12. Spider venomics: implications for drug discovery.

    PubMed

    Pineda, Sandy S; Undheim, Eivind A B; Rupasinghe, Darshani B; Ikonomopoulou, Maria P; King, Glenn F

    2014-10-01

    Over a period of more than 300 million years, spiders have evolved complex venoms containing an extraordinary array of toxins for prey capture and defense against predators. The major components of most spider venoms are small disulfide-bridged peptides that are highly stable and resistant to proteolytic degradation. Moreover, many of these peptides have high specificity and potency toward molecular targets of therapeutic importance. This unique combination of bioactivity and stability has made spider-venom peptides valuable both as pharmacological tools and as leads for drug development. This review describes recent advances in spider-venom-based drug discovery pipelines. We discuss spider-venom-derived peptides that are currently under investigation for treatment of a diverse range of pathologies including pain, stroke and cancer.

  13. Spider venomics: implications for drug discovery.

    PubMed

    Pineda, Sandy S; Undheim, Eivind A B; Rupasinghe, Darshani B; Ikonomopoulou, Maria P; King, Glenn F

    2014-10-01

    Over a period of more than 300 million years, spiders have evolved complex venoms containing an extraordinary array of toxins for prey capture and defense against predators. The major components of most spider venoms are small disulfide-bridged peptides that are highly stable and resistant to proteolytic degradation. Moreover, many of these peptides have high specificity and potency toward molecular targets of therapeutic importance. This unique combination of bioactivity and stability has made spider-venom peptides valuable both as pharmacological tools and as leads for drug development. This review describes recent advances in spider-venom-based drug discovery pipelines. We discuss spider-venom-derived peptides that are currently under investigation for treatment of a diverse range of pathologies including pain, stroke and cancer. PMID:25406008

  14. Effects of dimethoate on spiders from metal pollution gradient.

    PubMed

    Babczyńska, Agnieszka; Wilczek, Grazyna; Migula, Paweł

    2006-11-01

    In this study, an attempt has been made to assess whether a chronic exposure to metals in habitats under a strong industrial pressure might have equipped spiders with biochemical defensive mechanisms enabling them to survive an additional chemical stress. To check this, non-web-building wolf spiders Pardosa lugubris (Lycosidae) and funnel web Agelena labyrinthica (Agelenidae) were collected at five variously polluted meadows and, under laboratory conditions, intoxicated with either single or multiple dose of dimethoate (OP pesticide). Then the activities of detoxifying (carboxylesterase: CarE, glutathione S-transferase: GST), antioxidative (selene-dependent and selene-independent glutathione peroxidases: GPOX and GSTPx) enzymes as well as acetylcholinesterase as a biomarker of exposure to OP pesticides were measured. In web-building A. labyrinthica, even a single application of the pesticide caused the inhibition of CarE, GSTPx and GPOX in individuals from less polluted sites and AChE and GST in specimens pre-exposed to high metal concentrations. Multiple intoxication, irrespectively of the site, caused significant, in comparison to controls, decrease in CarE, AChE and GSTPx activities. Actively hunting P. lugubris seem more resistant to acute pesticide intoxication, since the spiders from each site had a constant level of GST and AChE. In individuals of this species from heavily polluted sites, the inhibition caused by multiple intoxication with dimethoate was stated only for glutathione peroxidases.

  15. Differential accumulation of heavy metals by web spiders and ground spiders in an old-field

    SciTech Connect

    Larsen, K.J.; Brewer, S.R.; Taylor, D.H. . Dept. of Zoology)

    1994-03-01

    Accumulation of the heavy metals Cd, Cu, Pb, and Zn by web spiders (orb weavers: Araneidae) and ground spiders was examined in an old-field that had been subjected to 11 years of nutrient enrichment. The study area consistent of six 0.1-ha plots treated from 1978 to 1988 with municipal sewage sludge containing heavy-metal contaminants, urea-phosphate fertilizer, or left as untreated controls. In 1991 and 1992, heavy-metal concentrations in the soil, ground spiders, and web spiders were measured with a flame AA spectrophotometer. Spiders accumulated Cd, Cu, and Zn to concentrations greater than those present in the soil but did not accumulate Pb. Ground spiders contained significantly higher levels of Cd and Cu than web spiders, whereas web spiders contained slightly greater levels of Pb than ground spiders. No trend between spider guilds was apparent for Zn accumulation. To understand the impact of the application of metal-contaminated municipal sludge on ecosystem, the toxicological effects on the biology and behavior of major biotic components in terrestrial food webs must be known.

  16. 'Natural experiment' demonstrates top-down control of spiders by birds on a landscape level.

    PubMed

    Rogers, Haldre; Hille Ris Lambers, Janneke; Miller, Ross; Tewksbury, Joshua J

    2012-01-01

    The combination of small-scale manipulative experiments and large-scale natural experiments provides a powerful approach for demonstrating the importance of top-down trophic control on the ecosystem scale. The most compelling natural experiments have come from studies examining the landscape-scale loss of apex predators like sea otters, wolves, fish and land crabs. Birds are dominant apex predators in terrestrial systems around the world, yet all studies on their role as predators have come from small-scale experiments; the top-down impact of bird loss on their arthropod prey has yet to be examined at a landscape scale. Here, we use a unique natural experiment, the extirpation of insectivorous birds from nearly all forests on the island of Guam by the invasive brown tree snake, to produce the first assessment of the impacts of bird loss on their prey. We focused on spiders because experimental studies showed a consistent top-down effect of birds on spiders. We conducted spider web surveys in native forest on Guam and three nearby islands with healthy bird populations. Spider web densities on the island of Guam were 40 times greater than densities on islands with birds during the wet season, and 2.3 times greater during the dry season. These results confirm the general trend from manipulative experiments conducted in other systems however, the effect size was much greater in this natural experiment than in most manipulative experiments. In addition, bird loss appears to have removed the seasonality of spider webs and led to larger webs in at least one spider species in the forests of Guam than on nearby islands with birds. We discuss several possible mechanisms for the observed changes. Overall, our results suggest that effect sizes from smaller-scale experimental studies may significantly underestimate the impact of bird loss on spider density as demonstrated by this large-scale natural experiment. PMID:22970126

  17. 'Natural experiment' demonstrates top-down control of spiders by birds on a landscape level.

    PubMed

    Rogers, Haldre; Hille Ris Lambers, Janneke; Miller, Ross; Tewksbury, Joshua J

    2012-01-01

    The combination of small-scale manipulative experiments and large-scale natural experiments provides a powerful approach for demonstrating the importance of top-down trophic control on the ecosystem scale. The most compelling natural experiments have come from studies examining the landscape-scale loss of apex predators like sea otters, wolves, fish and land crabs. Birds are dominant apex predators in terrestrial systems around the world, yet all studies on their role as predators have come from small-scale experiments; the top-down impact of bird loss on their arthropod prey has yet to be examined at a landscape scale. Here, we use a unique natural experiment, the extirpation of insectivorous birds from nearly all forests on the island of Guam by the invasive brown tree snake, to produce the first assessment of the impacts of bird loss on their prey. We focused on spiders because experimental studies showed a consistent top-down effect of birds on spiders. We conducted spider web surveys in native forest on Guam and three nearby islands with healthy bird populations. Spider web densities on the island of Guam were 40 times greater than densities on islands with birds during the wet season, and 2.3 times greater during the dry season. These results confirm the general trend from manipulative experiments conducted in other systems however, the effect size was much greater in this natural experiment than in most manipulative experiments. In addition, bird loss appears to have removed the seasonality of spider webs and led to larger webs in at least one spider species in the forests of Guam than on nearby islands with birds. We discuss several possible mechanisms for the observed changes. Overall, our results suggest that effect sizes from smaller-scale experimental studies may significantly underestimate the impact of bird loss on spider density as demonstrated by this large-scale natural experiment.

  18. Sperm Dynamics in Spiders (Araneae): Ultrastructural Analysis of the Sperm Activation Process in the Garden Spider Argiope bruennichi (Scopoli, 1772)

    PubMed Central

    Vöcking, Oliver; Uhl, Gabriele; Michalik, Peter

    2013-01-01

    Storage of sperm inside the female genital tract is an integral phase of reproduction in many animal species. The sperm storage site constitutes the arena for sperm activation, sperm competition and female sperm choice. Consequently, to understand animal mating systems information on the processes that occur from sperm transfer to fertilization is required. Here, we focus on sperm activation in spiders. Male spiders produce sperm whose cell components are coiled within the sperm cell and that are surrounded by a proteinaceous sheath. These inactive and encapsulated sperm are transferred to the female spermathecae where they are stored for later fertilization. We analyzed the ultrastructural changes of sperm cells during residency time in the female genital system of the orb-web spider Argiope bruennichi. We found three clearly distinguishable sperm conditions: encapsulated sperm (secretion sheath present), decapsulated (secretion sheath absent) and uncoiled sperm (cell components uncoiled, presumably activated). After insemination, sperm remain in the encapsulated condition for several days and become decapsulated after variable periods of time. A variable portion of the decapsulated sperm transforms rapidly to the uncoiled condition resulting in a simultaneous occurrence of decapsulated and uncoiled sperm. After oviposition, only decapsulated and uncoiled sperm are left in the spermathecae, strongly suggesting that the activation process is not reversible. Furthermore, we found four different types of secretion in the spermathecae which might play a role in the decapsulation and activation process. PMID:24039790

  19. Sperm dynamics in spiders (Araneae): ultrastructural analysis of the sperm activation process in the garden spider Argiope bruennichi (Scopoli, 1772).

    PubMed

    Vöcking, Oliver; Uhl, Gabriele; Michalik, Peter

    2013-01-01

    Storage of sperm inside the female genital tract is an integral phase of reproduction in many animal species. The sperm storage site constitutes the arena for sperm activation, sperm competition and female sperm choice. Consequently, to understand animal mating systems information on the processes that occur from sperm transfer to fertilization is required. Here, we focus on sperm activation in spiders. Male spiders produce sperm whose cell components are coiled within the sperm cell and that are surrounded by a proteinaceous sheath. These inactive and encapsulated sperm are transferred to the female spermathecae where they are stored for later fertilization. We analyzed the ultrastructural changes of sperm cells during residency time in the female genital system of the orb-web spider Argiope bruennichi. We found three clearly distinguishable sperm conditions: encapsulated sperm (secretion sheath present), decapsulated (secretion sheath absent) and uncoiled sperm (cell components uncoiled, presumably activated). After insemination, sperm remain in the encapsulated condition for several days and become decapsulated after variable periods of time. A variable portion of the decapsulated sperm transforms rapidly to the uncoiled condition resulting in a simultaneous occurrence of decapsulated and uncoiled sperm. After oviposition, only decapsulated and uncoiled sperm are left in the spermathecae, strongly suggesting that the activation process is not reversible. Furthermore, we found four different types of secretion in the spermathecae which might play a role in the decapsulation and activation process.

  20. Spatio-temporal analysis of foraging behaviors of Anelosimus studiosus utilizing mathematical modeling of multiple spider interaction on a cooperative web.

    PubMed

    Quijano, Alex John; Joyner, Michele L; Ross, Chelsea; Watts, J Colton; Seier, Edith; Jones, Thomas C

    2016-11-01

    In this paper, we develop a model for predation movements of a subsocial spider species, Anelosimus studiosus. We expand on a previous model to include multiple spider interaction on the web as well as a latency period during predation. We then use the model to test different spatial configurations to determine the optimal spacing of spiders within a colony for successful capture during predation. The model simulations indicate that spiders uniformly spacing out along the edge of the web results in the most successful predation strategy. This is similar to the behavior observed by Ross (2013) in which it was determined to be statistically significant that during certain times of the day, spiders were positioned along the edge more than expected under complete spatial randomness. PMID:27544421

  1. Spatio-temporal analysis of foraging behaviors of Anelosimus studiosus utilizing mathematical modeling of multiple spider interaction on a cooperative web.

    PubMed

    Quijano, Alex John; Joyner, Michele L; Ross, Chelsea; Watts, J Colton; Seier, Edith; Jones, Thomas C

    2016-11-01

    In this paper, we develop a model for predation movements of a subsocial spider species, Anelosimus studiosus. We expand on a previous model to include multiple spider interaction on the web as well as a latency period during predation. We then use the model to test different spatial configurations to determine the optimal spacing of spiders within a colony for successful capture during predation. The model simulations indicate that spiders uniformly spacing out along the edge of the web results in the most successful predation strategy. This is similar to the behavior observed by Ross (2013) in which it was determined to be statistically significant that during certain times of the day, spiders were positioned along the edge more than expected under complete spatial randomness.

  2. Untangling spider silk evolution with spidroin terminal domains

    PubMed Central

    2010-01-01

    Background Spidroins are a unique family of large, structural proteins that make up the bulk of spider silk fibers. Due to the highly variable nature of their repetitive sequences, spidroin evolutionary relationships have principally been determined from their non-repetitive carboxy (C)-terminal domains, though they offer limited character data. The few known spidroin amino (N)-terminal domains have been difficult to obtain, but potentially contain critical phylogenetic information for reconstructing the diversification of spider silks. Here we used silk gland expression data (ESTs) from highly divergent species to evaluate the functional significance and phylogenetic utility of spidroin N-terminal domains. Results We report 11 additional spidroin N-termini found by sequencing ~1,900 silk gland cDNAs from nine spider species that shared a common ancestor > 240 million years ago. In contrast to their hyper-variable repetitive regions, spidroin N-terminal domains have retained striking similarities in sequence identity, predicted secondary structure, and hydrophobicity. Through separate and combined phylogenetic analyses of N-terminal domains and their corresponding C-termini, we find that combined analysis produces the most resolved trees and that N-termini contribute more support and less conflict than the C-termini. These analyses show that paralogs largely group by silk gland type, except for the major ampullate spidroins. Moreover, spidroin structural motifs associated with superior tensile strength arose early in the history of this gene family, whereas a motif conferring greater extensibility convergently evolved in two distantly related paralogs. Conclusions A non-repetitive N-terminal domain appears to be a universal attribute of spidroin proteins, likely retained from the origin of spider silk production. Since this time, spidroin N-termini have maintained several features, consistent with this domain playing a key role in silk assembly. Phylogenetic

  3. Diet of the critically endangered brown spider monkey (Ateles hybridus) in an inter-Andean lowland rainforest in Colombia.

    PubMed

    Link, Andrés; Galvis, Nelson; Marquez, Mateo; Guerrero, Jane; Solano, Camila; Stevenson, Pablo R

    2012-12-01

    Brown spider monkeys (Ateles hybridus) are one of the least known and more threatened primates in the Neotropics. Recognized as a species about a decade ago, field studies on these endangered primates have mainly focused on estimating local population densities. Since 2006, we habituated a group of wild brown spider monkeys at Serranía de Las Quinchas, Colombia, and studied their feeding ecology during 2.5 years using focal "subgroup" sampling, and conducted phenological surveys in order to estimate habitat-wide fruit availability. Based on 847 hr of behavioral follows, brown spider monkeys spent approximately 25% of their time in feeding activities, and fed from fruits and leaves on at least 123 plant species. Ripe fruits were the most important item in the diet of A. hybridus at Las Quinchas comprising 92% of their feeding time. Probably due to the minor variation in the monthly proportion of fruits in brown spider monkey's diet throughout this study, there was no relation between habitat-wide fruit availability and the proportion of fruit included in their monthly diet. The diet of brown spider monkeys at Las Quinchas is toward the high end of fruit intake, even within other wild spider monkeys' populations, suggesting that these endangered primates might also be facing the challenges of being a large bodied fruit specialist under a regional scenario of habitat loss and fragmentation.

  4. Spinning a laser web: predicting spider distributions using LiDAR.

    PubMed

    Vierling, K T; Bässler, C; Brandl, R; Vierling, L A; Weiss, I; Müller, J

    2011-03-01

    LiDAR remote sensing has been used to examine relationships between vertebrate diversity and environmental characteristics, but its application to invertebrates has been limited. Our objectives were to determine whether LiDAR-derived variables could be used to accurately describe single-species distributions and community characteristics of spiders in remote forested and mountainous terrain. We collected over 5300 spiders across multiple transects in the Bavarian National Park (Germany) using pitfall traps. We examined spider community characteristics (species richness, the Shannon index, the Simpson index, community composition, mean body size, and abundance) and single-species distribution and abundance with LiDAR variables and ground-based measurements. We used the R2 and partial R2 provided by variance partitioning to evaluate the predictive power of LiDAR-derived variables compared to ground measurements for each of the community characteristics. The total adjusted R2 for species richness, the Shannon index, community species composition, and body size had a range of 25-57%. LiDAR variables and ground measurements both contributed >80% to the total predictive power. For species composition, the explained variance was approximately 32%, which was significantly greater than expected by chance. The predictive power of LiDAR-derived variables was comparable or superior to that of the ground-based variables for examinations of single-species distributions, and it explained up to 55% of the variance. The predictability of species distributions was higher for species that had strong associations with shade in open-forest habitats, and this niche position has been well documented across the European continent for spider species. The similar statistical performance between LiDAR and ground-based measures at our field sites indicated that deriving spider community and species distribution information using LiDAR data can provide not only high predictive power at

  5. Spinning a laser web: predicting spider distributions using LiDAR.

    PubMed

    Vierling, K T; Bässler, C; Brandl, R; Vierling, L A; Weiss, I; Müller, J

    2011-03-01

    LiDAR remote sensing has been used to examine relationships between vertebrate diversity and environmental characteristics, but its application to invertebrates has been limited. Our objectives were to determine whether LiDAR-derived variables could be used to accurately describe single-species distributions and community characteristics of spiders in remote forested and mountainous terrain. We collected over 5300 spiders across multiple transects in the Bavarian National Park (Germany) using pitfall traps. We examined spider community characteristics (species richness, the Shannon index, the Simpson index, community composition, mean body size, and abundance) and single-species distribution and abundance with LiDAR variables and ground-based measurements. We used the R2 and partial R2 provided by variance partitioning to evaluate the predictive power of LiDAR-derived variables compared to ground measurements for each of the community characteristics. The total adjusted R2 for species richness, the Shannon index, community species composition, and body size had a range of 25-57%. LiDAR variables and ground measurements both contributed >80% to the total predictive power. For species composition, the explained variance was approximately 32%, which was significantly greater than expected by chance. The predictive power of LiDAR-derived variables was comparable or superior to that of the ground-based variables for examinations of single-species distributions, and it explained up to 55% of the variance. The predictability of species distributions was higher for species that had strong associations with shade in open-forest habitats, and this niche position has been well documented across the European continent for spider species. The similar statistical performance between LiDAR and ground-based measures at our field sites indicated that deriving spider community and species distribution information using LiDAR data can provide not only high predictive power at

  6. Spider silk gut: Development and characterization of a novel strong spider silk fiber

    PubMed Central

    Jiang, Ping; Marí-Buyé, Núria; Madurga, Rodrigo; Arroyo-Hernández, María; Solanas, Concepción; Gañán, Alfonso; Daza, Rafael; Plaza, Gustavo R.; Guinea, Gustavo V.; Elices, Manuel; Cenis, José Luis; Pérez-Rigueiro, José

    2014-01-01

    Spider silk fibers were produced through an alternative processing route that differs widely from natural spinning. The process follows a procedure traditionally used to obtain fibers directly from the glands of silkworms and requires exposure to an acid environment and subsequent stretching. The microstructure and mechanical behavior of the so-called spider silk gut fibers can be tailored to concur with those observed in naturally spun spider silk, except for effects related with the much larger cross-sectional area of the former. In particular spider silk gut has a proper ground state to which the material can revert independently from its previous loading history by supercontraction. A larger cross-sectional area implies that spider silk gut outperforms the natural material in terms of the loads that the fiber can sustain. This property suggests that it could substitute conventional spider silk fibers in some intended uses, such as sutures and scaffolds in tissue engineering. PMID:25475975

  7. Molecular Architecture and Evolution of a Modular Spider Silk Protein Gene

    NASA Astrophysics Data System (ADS)

    Hayashi, Cheryl Y.; Lewis, Randolph V.

    2000-02-01

    Spider flagelliform silk is one of the most elastic natural materials known. Extensive sequencing of spider silk genes has shown that the exons and introns of the flagelliform gene underwent intragenic concerted evolution. The intron sequences are more homogenized within a species than are the exons. This pattern can be explained by extreme mutation and recombination pressures on the internally repetitive exons. The iterated sequences within exons encode protein structures that are critical to the function of silks. Therefore, attributes that make silks exceptional biomaterials may also hinder the fixation of optimally adapted protein sequences.

  8. A rare finding of mites (Arachnida: Acari: Leeuwenhoekiidae) parasitising a whip spider (Arachnida: Amblypygi: Charinidae).

    PubMed

    Gonçalves-Souza, Thiago; Giupponi, Alessandro P L; Hernandes, Fabio A

    2014-04-01

    Twelve larvae of unidentified species of Odontacarus Ewing, 1929 (Acari: Leeuwenhoekiidae) were found parasitising an adult male whip spider Charinus brasilianus Weygoldt (Charinidae) in Santa Teresa, mountainous region of Espirito Santo state, southeastern Brazil. These larvae occurred in the intersegmental membrane of prosoma and legs. This is the first report of ectoparasitic mites infecting a charinid whip spider and the first record of leeuwenhoekiid mites parasitising an invertebrate host. We suggest that future studies are essential to understand the reasons why these events of parasitism are so rare in the order Amblypygi.

  9. Ground Spider Guilds and Functional Diversity in Native Pine Woodlands and Eucalyptus Plantations.

    PubMed

    Corcuera, Pablo; Valverde, Pedro Luis; Jiménez, María Luisa; Ponce-Mendoza, Alejandro; De la Rosa, Gabriela; Nieto, Gisela

    2016-04-01

    Vegetation structure and floristics have a strong influence on the relative abundance of spider guilds and functional diversity of terrestrial arthropods. Human activities have transformed much of the temperate woodlands. The aim of this study was to test five predictions related to the guild distribution and functional diversity of the ground spider communities of Eucalyptus plantations and native pine woodlands in western Mexico. Spiders were collected every fortnight from September to November from 15 pitfalls positioned in each of the eight sites. We also assessed the cover of grasses, herbs, shrubs, and leaf litter in each site. We found that the abundances of ground hunters and sheet weavers between plantations and pine woodlands were different. Nevertheless, there was not a consistent difference between sites of each of the vegetation types. Most species of ground hunters, sheet web weavers, and many other hunters were associated with litter and the grass cover. Nonetheless, in some cases, species of different families belonging to the same guild responded to different variables. Wolf spiders were related to the grass Aristida stricta Micheaux, 1803, while the species of the other families of ground hunters were associated with leaf litter. One Eucalyptus plantation and one pine woodland had the highest functional diversity of all sites. These sites have a well developed litter and grass cover. Our study suggests that the abundance of litter and a high cover of grasses explain the occurrence of species with different traits, and these habitat components results in a high functional diversity.

  10. Influence of the biogeospatial environment on the distribution of spider communities

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The maintenance of local biodiversity is an important aspect of the long-term sustainability of agricultural production. Maintaining biodiversity, especially in regards to predator species, promotes natural pest control and many other ecosystem services. Spiders (Araneae) often prey upon common pest...

  11. Molecular identification of adult and juvenile linyphiid and theridiid spiders in Alpine glacier foreland communities.

    PubMed

    Raso, Lorna; Sint, Daniela; Rief, Alexander; Kaufmann, Rüdiger; Traugott, Michael

    2014-01-01

    In glacier forelands spiders constitute a large proportion of the invertebrate community. Therefore, it is important to be able to determine the species that can be found in these areas. Linyphiid and theridiid spider identification is currently not possible in juvenile specimens using traditional morphological based methods, however, a large proportion of the population in these areas are usually juveniles. Molecular methods permit identification of species at different life stages, making juvenile identification possible. In this study we tested a molecular tool to identify the 10 most common species of Linyphiidae and Theridiidae found in three glacier foreland communities of the Austrian Alps. Two multiplex PCR systems were developed and over 90% of the 753 field-collected spiders were identified successfully. The species targeted were found to be common in all three valleys during the summer of 2010. A comparison between the molecular and morphological data showed that although there was a slight difference in the results, the overall outcome was the same independently of the identification method used. We believe the quick and reliable identification of the spiders via the multiplex PCR assays developed here will aid the study of these families in Alpine habitats.

  12. Molecular Identification of Adult and Juvenile Linyphiid and Theridiid Spiders in Alpine Glacier Foreland Communities

    PubMed Central

    Raso, Lorna; Sint, Daniela; Rief, Alexander; Kaufmann, Rüdiger; Traugott, Michael

    2014-01-01

    In glacier forelands spiders constitute a large proportion of the invertebrate community. Therefore, it is important to be able to determine the species that can be found in these areas. Linyphiid and theridiid spider identification is currently not possible in juvenile specimens using traditional morphological based methods, however, a large proportion of the population in these areas are usually juveniles. Molecular methods permit identification of species at different life stages, making juvenile identification possible. In this study we tested a molecular tool to identify the 10 most common species of Linyphiidae and Theridiidae found in three glacier foreland communities of the Austrian Alps. Two multiplex PCR systems were developed and over 90% of the 753 field-collected spiders were identified successfully. The species targeted were found to be common in all three valleys during the summer of 2010. A comparison between the molecular and morphological data showed that although there was a slight difference in the results, the overall outcome was the same independently of the identification method used. We believe the quick and reliable identification of the spiders via the multiplex PCR assays developed here will aid the study of these families in Alpine habitats. PMID:25050841

  13. Spiders spinning electrically charged nano-fibres.

    PubMed

    Kronenberger, Katrin; Vollrath, Fritz

    2015-01-01

    Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland-duct-spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders.

  14. Spiders spinning electrically charged nano-fibres.

    PubMed

    Kronenberger, Katrin; Vollrath, Fritz

    2015-01-01

    Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland-duct-spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders. PMID:25631231

  15. Further development for testing the effects of pesticides on wolf spiders.

    PubMed

    Hof, A; Heimann, D; Römbke, J

    1995-08-01

    Based on preliminary guidelines of the "Biologische Bundesanstalt für Land- und Forstwirtschaft" (BBA, Germany) for testing the effects of pesticides on wolf spiders (genus Pardosa, Lycosidae, Araneae), two test series were carried out with the pesticides Karate (a.i. lambda-cyhalothrin) and a noname product. At start of the test the pesticides were applied onto spiders and a sand substrate with an application apparatus. Thereafter, the mortality, the behavior, and the feeding rate were observed up to 14 days. Ninety-eight percent of the tested individuals belonged to the species Pardosa amentata. The results of the Karate experiments indicated a considerably higher reaction for males than for females. The aggression of the spiders proved to be a stress factor when the vessel was inhabited by more than one spider and caused higher mortality in individuals treated with pesticides. Spiders raised from cocoons in the laboratory were in general less sensitive than animals collected in the field and accustomed to laboratory conditions. Experiments performed with the noname pesticide in different seasons revealed that the sensitivity of the animals was influenced by their age. The parameters of mortality, behavior, and feeding rate proved to provide data adequate for evaluating the lethal and sublethal effects of the substances examined.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Spider Silk Fibers Spun from Soluble Recombinant Silk Produced in Mammalian Cells

    NASA Astrophysics Data System (ADS)

    Lazaris, Anthoula; Arcidiacono, Steven; Huang, Yue; Zhou, Jiang-Feng; Duguay, François; Chretien, Nathalie; Welsh, Elizabeth A.; Soares, Jason W.; Karatzas, Costas N.

    2002-01-01

    Spider silks are protein-based ``biopolymer'' filaments or threads secreted by specialized epithelial cells as concentrated soluble precursors of highly repetitive primary sequences. Spider dragline silk is a flexible, lightweight fiber of extraordinary strength and toughness comparable to that of synthetic high-performance fibers. We sought to ``biomimic'' the process of spider silk production by expressing in mammalian cells the dragline silk genes (ADF-3/MaSpII and MaSpI) of two spider species. We produced soluble recombinant (rc)-dragline silk proteins with molecular masses of 60 to 140 kilodaltons. We demonstrated the wet spinning of silk monofilaments spun from a concentrated aqueous solution of soluble rc-spider silk protein (ADF-3; 60 kilodaltons) under modest shear and coagulation conditions. The spun fibers were water insoluble with a fine diameter (10 to 40 micrometers) and exhibited toughness and modulus values comparable to those of native dragline silks but with lower tenacity. Dope solutions with rc-silk protein concentrations >20% and postspinning draw were necessary to achieve improved mechanical properties of the spun fibers. Fiber properties correlated with finer fiber diameter and increased birefringence.

  17. Molecular evolution of arthropod color vision deduced from multiple opsin genes of jumping spiders.

    PubMed

    Koyanagi, Mitsumasa; Nagata, Takashi; Katoh, Kazutaka; Yamashita, Shigeki; Tokunaga, Fumio

    2008-02-01

    Among terrestrial animals, only vertebrates and arthropods possess wavelength-discrimination ability, so-called "color vision". For color vision to exist, multiple opsins which encode visual pigments sensitive to different wavelengths of light are required. While the molecular evolution of opsins in vertebrates has been well investigated, that in arthropods remains to be elucidated. This is mainly due to poor information about the opsin genes of non-insect arthropods. To obtain an overview of the evolution of color vision in Arthropoda, we isolated three kinds of opsins, Rh1, Rh2, and Rh3, from two jumping spider species, Hasarius adansoni and Plexippus paykulli. These spiders belong to Chelicerata, one of the most distant groups from Hexapoda (insects), and have color vision as do insects. Phylogenetic analyses of jumping spider opsins revealed a birth and death process of color vision evolution in the arthropod lineage. Phylogenetic positions of jumping spider opsins revealed that at least three opsins had already existed before the Chelicerata-Pancrustacea split. In addition, sequence comparison between jumping spider Rh3 and the shorter wavelength-sensitive opsins of insects predicted that an opsin of the ancestral arthropod had the lysine residue responsible for UV sensitivity. These results strongly suggest that the ancestral arthropod had at least trichromatic vision with a UV pigment and two visible pigments. Thereafter, in each pancrustacean and chelicerate lineage, the opsin repertoire was reconstructed by gene losses, gene duplications, and function-altering amino acid substitutions, leading to evolution of color vision. PMID:18217181

  18. The prevalence of brown widow and black widow spiders (Araneae: Theridiidae) in urban southern California.

    PubMed

    Vetter, Richard S; Vincent, Leonard S; Danielsen, Douglas W R; Reinker, Kathryn I; Clarke, Daniel E; Itnyre, Amelia A; Kabashima, John N; Rust, Michael K

    2012-07-01

    The brown widow spider, Latrodectus geometricus C. L. Koch, has become newly established in southern California during the first decade of the 21st century. Brown widows and egg sacs were collected within the urban Los Angeles Basin using timed searches. We also collected and compared the abundance and distribution of the native western black widow spider, Latrodectus hesperus Chamberlin & Ivie, to brown widows. Brown widows were very common around urban structures especially outside homes, in parks, under playground equipment, in plant nurseries and landscaping areas, greatly outnumbering native western black widows, and were very rare or nonexistent in garages, agricultural crops, and natural areas. Western black widows predominated in xeric habitats and were less prevalent around homes. Neither species was found in the living space of homes. In southern California, envenomation risk exists because brown widows are now common in urban areas and the spiders hide where people place their fingers and exert pressure to move objects (e.g., under the curled lip of potted plants, in the recessed handle of plastic trash bins). Nonetheless, brown widow spider bites are less toxic than those of native western black widow spiders and, hence, if they are displacing black widows, overall widow envenomation risk may actually be lower than before brown widow establishment. PMID:22897057

  19. Molecular evolution of arthropod color vision deduced from multiple opsin genes of jumping spiders.

    PubMed

    Koyanagi, Mitsumasa; Nagata, Takashi; Katoh, Kazutaka; Yamashita, Shigeki; Tokunaga, Fumio

    2008-02-01

    Among terrestrial animals, only vertebrates and arthropods possess wavelength-discrimination ability, so-called "color vision". For color vision to exist, multiple opsins which encode visual pigments sensitive to different wavelengths of light are required. While the molecular evolution of opsins in vertebrates has been well investigated, that in arthropods remains to be elucidated. This is mainly due to poor information about the opsin genes of non-insect arthropods. To obtain an overview of the evolution of color vision in Arthropoda, we isolated three kinds of opsins, Rh1, Rh2, and Rh3, from two jumping spider species, Hasarius adansoni and Plexippus paykulli. These spiders belong to Chelicerata, one of the most distant groups from Hexapoda (insects), and have color vision as do insects. Phylogenetic analyses of jumping spider opsins revealed a birth and death process of color vision evolution in the arthropod lineage. Phylogenetic positions of jumping spider opsins revealed that at least three opsins had already existed before the Chelicerata-Pancrustacea split. In addition, sequence comparison between jumping spider Rh3 and the shorter wavelength-sensitive opsins of insects predicted that an opsin of the ancestral arthropod had the lysine residue responsible for UV sensitivity. These results strongly suggest that the ancestral arthropod had at least trichromatic vision with a UV pigment and two visible pigments. Thereafter, in each pancrustacean and chelicerate lineage, the opsin repertoire was reconstructed by gene losses, gene duplications, and function-altering amino acid substitutions, leading to evolution of color vision.

  20. The multiple disguises of spiders: web colour and decorations, body colour and movement

    PubMed Central

    Théry, Marc; Casas, Jérôme

    2008-01-01

    Diverse functions have been assigned to the visual appearance of webs, spiders and web decorations, including prey attraction, predator deterrence and camouflage. Here, we review the pertinent literature, focusing on potential camouflage and mimicry. Webs are often difficult to detect in a heterogeneous visual environment. Static and dynamic web distortions are used to escape visual detection by prey, although particular silk may also attract prey. Recent work using physiological models of vision taking into account visual environments rarely supports the hypothesis of spider camouflage by decorations, but most often the prey attraction and predator confusion hypotheses. Similarly, visual modelling shows that spider coloration is effective in attracting prey but not in conveying camouflage. Camouflage through colour change might be used by particular crab spiders to hide from predator or prey on flowers of different coloration. However, results obtained on a non-cryptic crab spider suggest that an alternative function of pigmentation may be to avoid UV photodamage through the transparent cuticle. Numerous species are clearly efficient locomotory mimics of ants, particularly in the eyes of their predators. We close our paper by highlighting gaps in our knowledge. PMID:18990672

  1. The prevalence of brown widow and black widow spiders (Araneae: Theridiidae) in urban southern California.

    PubMed

    Vetter, Richard S; Vincent, Leonard S; Danielsen, Douglas W R; Reinker, Kathryn I; Clarke, Daniel E; Itnyre, Amelia A; Kabashima, John N; Rust, Michael K

    2012-07-01

    The brown widow spider, Latrodectus geometricus C. L. Koch, has become newly established in southern California during the first decade of the 21st century. Brown widows and egg sacs were collected within the urban Los Angeles Basin using timed searches. We also collected and compared the abundance and distribution of the native western black widow spider, Latrodectus hesperus Chamberlin & Ivie, to brown widows. Brown widows were very common around urban structures especially outside homes, in parks, under playground equipment, in plant nurseries and landscaping areas, greatly outnumbering native western black widows, and were very rare or nonexistent in garages, agricultural crops, and natural areas. Western black widows predominated in xeric habitats and were less prevalent around homes. Neither species was found in the living space of homes. In southern California, envenomation risk exists because brown widows are now common in urban areas and the spiders hide where people place their fingers and exert pressure to move objects (e.g., under the curled lip of potted plants, in the recessed handle of plastic trash bins). Nonetheless, brown widow spider bites are less toxic than those of native western black widow spiders and, hence, if they are displacing black widows, overall widow envenomation risk may actually be lower than before brown widow establishment.

  2. [Total upper lip necrosis and loxoscelism caused by violin spider bite].

    PubMed

    Bogdán, Sándor; Barabás, József; Zacher, Gábor; Huszár, Tamás; Velich, Norbert; Szabó, György; Németh, Zsolt

    2005-11-01

    Arthropods and in particular spiders are a common embodiment of our fears, despite the fact that only a few species are dangerous to man. The authors present a case involving severe local and general reactions to a loxosceles (brown recluse spider) bite. They give an overview of the occurrence of loxosceles spiders, the signs and symptoms of envenomation and the therapeutic possibilities. The severe symptoms presenting following loxosceles envenomation is termed loxoscelism. Loxoscelism is characterised by local soft tissue necrosis of varying degree at the site of the sting, and rarely, life-threatening general reactions, such as haemolysis with ensuing anaemia, and renal failure. Therapeutic interventions following loxosceles bites range from dapsone treatment to hyperbaric oxygen therapy, but the most promising therapy is the use of the antiserum, commercially available in certain South-American countries where loxosceles bites are common. Treatment of soft tissue necrosis consists of necrectomy and surgical reconstruction following the resolution of the inflammatory symptoms. PMID:16304811

  3. Biomaterial evolution parallels behavioral innovation in the origin of orb-like spider webs

    NASA Astrophysics Data System (ADS)

    Blackledge, Todd A.; Kuntner, Matjaž; Marhabaie, Mohammad; Leeper, Thomas C.; Agnarsson, Ingi

    2012-11-01

    Correlated evolution of traits can act synergistically to facilitate organism function. But, what happens when constraints exist on the evolvability of some traits, but not others? The orb web was a key innovation in the origin of >12,000 species of spiders. Orb evolution hinged upon the origin of novel spinning behaviors and innovations in silk material properties. In particular, a new major ampullate spidroin protein (MaSp2) increased silk extensibility and toughness, playing a critical role in how orb webs stop flying insects. Here, we show convergence between pseudo-orb-weaving Fecenia and true orb spiders. As in the origin of true orbs, Fecenia dragline silk improved significantly compared to relatives. But, Fecenia silk lacks the high compliance and extensibility found in true orb spiders, likely due in part to the absence of MaSp2. Our results suggest how constraints limit convergent evolution and provide insight into the evolution of nature's toughest fibers.

  4. Persistence and variation in microstructural design during the evolution of spider silk

    NASA Astrophysics Data System (ADS)

    Madurga, R.; Blackledge, T. A.; Perea, B.; Plaza, G. R.; Riekel, C.; Burghammer, M.; Elices, M.; Guinea, G.; Pérez-Rigueiro, J.

    2015-10-01

    The extraordinary mechanical performance of spider dragline silk is explained by its highly ordered microstructure and results from the sequences of its constituent proteins. This optimized microstructural organization simultaneously achieves high tensile strength and strain at breaking by taking advantage of weak molecular interactions. However, elucidating how the original design evolved over the 400 million year history of spider silk, and identifying the basic relationships between microstructural details and performance have proven difficult tasks. Here we show that the analysis of maximum supercontracted single spider silk fibers using X ray diffraction shows a complex picture of silk evolution where some key microstructural features are conserved phylogenetically while others show substantial variation even among closely related species. This new understanding helps elucidate which microstructural features need to be copied in order to produce the next generation of biomimetic silk fibers.

  5. Persistence and variation in microstructural design during the evolution of spider silk

    PubMed Central

    Madurga, R.; Blackledge, T. A.; Perea, B.; Plaza, G. R.; Riekel, C.; Burghammer, M.; Elices, M.; Guinea, G.; Pérez-Rigueiro, J.

    2015-01-01

    The extraordinary mechanical performance of spider dragline silk is explained by its highly ordered microstructure and results from the sequences of its constituent proteins. This optimized microstructural organization simultaneously achieves high tensile strength and strain at breaking by taking advantage of weak molecular interactions. However, elucidating how the original design evolved over the 400 million year history of spider silk, and identifying the basic relationships between microstructural details and performance have proven difficult tasks. Here we show that the analysis of maximum supercontracted single spider silk fibers using X ray diffraction shows a complex picture of silk evolution where some key microstructural features are conserved phylogenetically while others show substantial variation even among closely related species. This new understanding helps elucidate which microstructural features need to be copied in order to produce the next generation of biomimetic silk fibers. PMID:26438975

  6. Composition and substrate-dependent strength of the silken attachment discs in spiders.

    PubMed

    Grawe, Ingo; Wolff, Jonas O; Gorb, Stanislav N

    2014-09-01

    Araneomorph spiders have evolved different silks with dissimilar material properties, serving different purposes. The two-compound pyriform secretion is used to glue silk threads to substrates or to other threads. It is applied in distinct patterns, called attachment discs. Although ubiquitously found in spider silk applications and hypothesized to be strong and versatile at low material consumption, the performance of attachment discs on different substrates remains unknown. Here, we analyse the detachment forces and fracture mechanics of the attachment discs spun by five different species on three different substrates, by pulling on the upstream part of the attached thread. Results show that although the adhesion of the pyriform glue is heavily affected by the substrate, even on Teflon it is frequently strong enough to hold the spider's weight. As plant surfaces are often difficult to wet, they are hypothesized to be the major driving force for evolution of the pyriform secretion.

  7. Composition and substrate-dependent strength of the silken attachment discs in spiders

    PubMed Central

    Grawe, Ingo; Wolff, Jonas O.; Gorb, Stanislav N.

    2014-01-01

    Araneomorph spiders have evolved different silks with dissimilar material properties, serving different purposes. The two-compound pyriform secretion is used to glue silk threads to substrates or to other threads. It is applied in distinct patterns, called attachment discs. Although ubiquitously found in spider silk applications and hypothesized to be strong and versatile at low material consumption, the performance of attachment discs on different substrates remains unknown. Here, we analyse the detachment forces and fracture mechanics of the attachment discs spun by five different species on three different substrates, by pulling on the upstream part of the attached thread. Results show that although the adhesion of the pyriform glue is heavily affected by the substrate, even on Teflon it is frequently strong enough to hold the spider's weight. As plant surfaces are often difficult to wet, they are hypothesized to be the major driving force for evolution of the pyriform secretion. PMID:25030386

  8. Biomaterial evolution parallels behavioral innovation in the origin of orb-like spider webs

    PubMed Central

    Blackledge, Todd A.; Kuntner, Matjaž; Marhabaie, Mohammad; Leeper, Thomas C.; Agnarsson, Ingi

    2012-01-01

    Correlated evolution of traits can act synergistically to facilitate organism function. But, what happens when constraints exist on the evolvability of some traits, but not others? The orb web was a key innovation in the origin of >12,000 species of spiders. Orb evolution hinged upon the origin of novel spinning behaviors and innovations in silk material properties. In particular, a new major ampullate spidroin protein (MaSp2) increased silk extensibility and toughness, playing a critical role in how orb webs stop flying insects. Here, we show convergence between pseudo-orb-weaving Fecenia and true orb spiders. As in the origin of true orbs, Fecenia dragline silk improved significantly compared to relatives. But, Fecenia silk lacks the high compliance and extensibility found in true orb spiders, likely due in part to the absence of MaSp2. Our results suggest how constraints limit convergent evolution and provide insight into the evolution of nature's toughest fibers. PMID:23150784

  9. The mechanical design of spider silks: from fibroin sequence to mechanical function.

    PubMed

    Gosline, J M; Guerette, P A; Ortlepp, C S; Savage, K N

    1999-12-01

    Spiders produce a variety of silks, and the cloning of genes for silk fibroins reveals a clear link between protein sequence and structure-property relationships. The fibroins produced in the spider's major ampullate (MA) gland, which forms the dragline and web frame, contain multiple repeats of motifs that include an 8-10 residue long poly-alanine block and a 24-35 residue long glycine-rich block. When fibroins are spun into fibres, the poly-alanine blocks form (&bgr;)-sheet crystals that crosslink the fibroins into a polymer network with great stiffness, strength and toughness. As illustrated by a comparison of MA silks from Araneus diadematus and Nephila clavipes, variation in fibroin sequence and properties between spider species provides the opportunity to investigate the design of these remarkable biomaterials.

  10. Biomaterial evolution parallels behavioral innovation in the origin of orb-like spider webs.

    PubMed

    Blackledge, Todd A; Kuntner, Matjaž; Marhabaie, Mohammad; Leeper, Thomas C; Agnarsson, Ingi

    2012-01-01

    Correlated evolution of traits can act synergistically to facilitate organism function. But, what happens when constraints exist on the evolvability of some traits, but not others? The orb web was a key innovation in the origin of >12,000 species of spiders. Orb evolution hinged upon the origin of novel spinning behaviors and innovations in silk material properties. In particular, a new major ampullate spidroin protein (MaSp2) increased silk extensibility and toughness, playing a critical role in how orb webs stop flying insects. Here, we show convergence between pseudo-orb-weaving Fecenia and true orb spiders. As in the origin of true orbs, Fecenia dragline silk improved significantly compared to relatives. But, Fecenia silk lacks the high compliance and extensibility found in true orb spiders, likely due in part to the absence of MaSp2. Our results suggest how constraints limit convergent evolution and provide insight into the evolution of nature's toughest fibers.

  11. INSECTICIDE RESISTANCE IN THE GROUND SPIDER, Pardosa sumatrana (THORELL, 1890; ARANEAE: LYCOSIDAE).

    PubMed

    Tahir, Hafiz Muhammad; Khizar, Farva; Naseem, Sajida; Yaqoob, Rabia; Samiullah, Khizar

    2016-09-01

    Elevated levels of insecticides detoxifying enzymes, such as esterases, glutathione S-transferases (GSTs), and cytochrome P-450 monooxygenases, act in the resistance mechanisms in insects. In the present study, levels of these enzymes in the insecticide-resistant ground spider Pardosa sumatrana (Thorell, 1890) were compared with a susceptible population (control) of the same species. Standard protocols were used for biochemical estimation of enzymes. The results showed significantly higher levels of nonspecific esterases and monooxygenases in resistant spiders compared to controls. The activity of GSTs was lower in the resistant spiders. Elevated levels of nonspecific esterases and monooxygenases suggest their role in metabolic resistance in P. sumatrana. The reduced levels of total protein contents revealed its possible consumption to meet energy demands. PMID:27312591

  12. It Was as Big as My Head, I Swear! Biased Spider Size Estimation in Spider Phobia

    PubMed Central

    Vasey, Michael W.; Vilensky, Michael R.; Heath, Jacqueline H.; Harbaugh, Casaundra N.; Buffington, Adam G.; Fazio, Russell H.

    2011-01-01

    The current study tested the association between fear and perception in spider phobic individuals (n = 57) within the context of a treatment outcome study. Participants completed 5 post-treatment Behavioral Approach Tasks (BATs) in which they encountered a live spider and were asked to provide spider size estimates. Consistent with predictions, results indicated that high levels of fear were associated with magnified perception of phobic stimuli. Specifically, we found a significant positive correlation between size estimates and self-reported fear while encountering spiders. Together with previous findings, these results further support the notion that fear is involved in the encoding and processing of perceptual information. PMID:21906909

  13. Biopolymers: shape memory in spider draglines.

    PubMed

    Emile, Olivier; Le Floch, Albert; Vollrath, Fritz

    2006-03-30

    The ductility and strength of spider draglines means that they outperform the best synthetic fibres, but surprisingly little is known about the torsional properties of this remarkable filament. Unlike a mountain climber swinging from a rope, a spider suspended from its silk thread hardly ever twists. Here we show that a spider dragline has a torsional shape 'memory' in that it can reversibly and totally recover its initial form without any external stimulus; its observed relaxation dynamics indicate that these biological molecules have successively different torsional constants. PMID:16572162

  14. New unidentate jumping spider genera (Araneae: Salticidae) from Australia.

    PubMed

    Richardson, Barry J

    2013-01-01

    The Australian fauna includes large numbers of undescribed, tiny, litter-living, jumping spiders. In this paper four monotypic new genera (Ananeon howardensis n. g. n. sp., Barraina anfracta n. g. n.sp., Frewena maculata n.g. n.s., and Pungalina weiri n.g, n.sp.) are described. Two species (Neon taylori n.sp. and Neon australis n. sp.) representing the two distinctive morphological patterns found in Australian species of this genus are also described. The former, similar in the morphology of the palp and genitalia to that found in many species from eastern Australia, is most similar in morphology to N. sumatranus Logunov 1998 from Indonesia and N. kovblyuki Logunov 2004 from the Crimea. The latter, and other similar species from South Australia and Western Australia, has palp morphology and fringing on L1 very similar to that seen in N. nojimai Ikeda 1995 from Japan. PMID:26106785

  15. Molecular diagnostics reveal spiders that exploit prey vibrational signals used in sexual communication.

    PubMed

    Virant-Doberlet, Meta; King, R Andrew; Polajnar, Jernej; Symondson, William O C

    2011-05-01

    Vibrational signalling is a widespread form of animal communication and, in the form of sexual communication, has been generally regarded as inherently short-range and a private communication channel, free from eavesdropping by generalist predators. A combination of fieldwork and laboratory experiments was used to test the hypothesis that predators can intercept and exploit such signals. First, we developed and characterized PCR primers specific for leafhoppers of the genus Aphrodes and specifically for the species Aphrodes makarovi. Spiders were collected from sites where leafhoppers were present and screened with these primers to establish which spider species were significant predators of this species during the mating period of these leafhoppers. Analysis using PCR of the gut contents of tangle-web spiders, Enoplognatha ovata (Theridiidae), showed that they consume leafhoppers in the field at a greater rate when signalling adults were present than when nymphs were dominant, suggesting that the spiders were using these vibrations signals to find their prey. Playback and microcosm experiments then showed that E. ovata can use the vibrational signals of male leafhoppers as a cue during foraging and, as a result, killed significantly more male than female A. makarovi. Our results show, for the first time, that arthropod predators can exploit prey vibrational communication to obtain information about prey availability and use this information to locate and capture prey. This may be a widespread mechanism for prey location, one that is likely to be a major unrecognized driver of evolution in both predators and prey.

  16. Decoupling fragmentation from habitat loss for spiders in patchy agricultural landscapes.

    PubMed

    Gavish, Yoni; Ziv, Yaron; Rosenzweig, Michael L

    2012-02-01

    Habitat loss reduces species diversity, but the effect of habitat fragmentation on number of species is less clear because fragmentation generally accompanies loss of habitat. We compared four methods that aim to decouple the effects of fragmentation from the effects of habitat loss. Two methods are based on species-area relations, one on Fisher's alpha index of diversity, and one on plots of cumulative number of species detected against cumulative area sampled. We used these methods to analyze the species diversity of spiders in 2, 3.2 × 4 km agricultural landscapes in Southern Judea Lowlands, Israel. Spider diversity increased as fragmentation increased with all four methods, probably not because of the additive within-patch processes, such as edge effect and heterogeneity. The positive relation between fragmentation and species diversity might reflect that most species can disperse through the fields during the wheat-growing season. We suggest that if a given area was designated for the conservation of spiders in Southern Judea Lowlands, Israel, a set of several small patches may maximize species diversity over time.

  17. Local trophic specialisation in a cosmopolitan spider (Araneae).

    PubMed

    Líznarová, Eva; Sentenská, Lenka; García, Luis Fernando; Pekár, Stano; Viera, Carmen

    2013-02-01

    Trophic specialisation can be observed in species with long-term constant exploitation of a certain prey in all populations or in a population of a species with short-term exploitation of a certain prey. While in the former case the species would evolve stereotyped or specialised trophic adaptations, the trophic traits of the latter should be versatile or generalised. Here, we studied the predatory behavioural adaptations of a presumed myrmecophagous spider, Oecobius navus. We chose two distinct populations, one in Portugal and the other in Uruguay. We analysed the actual prey of both populations and found that the Portuguese population feeds mainly on dipterans, while the Uruguayan population feeds mainly on ants. Indeed, dipterans and springtails in Portugal, and ants in Uruguay were the most abundant potential prey. In laboratory trials O. navus spiders recognised and captured a wide variety of prey. The capture efficiency of the Portuguese population measured as components of the handling time was higher for flies than for ants, while that of the Uruguayan population was higher for ants. We found phenotypic plasticity in behavioural traits that lead to increased capture efficiency with respect to the locally abundant prey, but it remains to be determined whether the traits of the two populations are genetically fixed. We conclude that O. navus is a euryphagous generalist predator which shows local specialisation on the locally abundant prey.

  18. Local trophic specialisation in a cosmopolitan spider (Araneae).

    PubMed

    Líznarová, Eva; Sentenská, Lenka; García, Luis Fernando; Pekár, Stano; Viera, Carmen

    2013-02-01

    Trophic specialisation can be observed in species with long-term constant exploitation of a certain prey in all populations or in a population of a species with short-term exploitation of a certain prey. While in the former case the species would evolve stereotyped or specialised trophic adaptations, the trophic traits of the latter should be versatile or generalised. Here, we studied the predatory behavioural adaptations of a presumed myrmecophagous spider, Oecobius navus. We chose two distinct populations, one in Portugal and the other in Uruguay. We analysed the actual prey of both populations and found that the Portuguese population feeds mainly on dipterans, while the Uruguayan population feeds mainly on ants. Indeed, dipterans and springtails in Portugal, and ants in Uruguay were the most abundant potential prey. In laboratory trials O. navus spiders recognised and captured a wide variety of prey. The capture efficiency of the Portuguese population measured as components of the handling time was higher for flies than for ants, while that of the Uruguayan population was higher for ants. We found phenotypic plasticity in behavioural traits that lead to increased capture efficiency with respect to the locally abundant prey, but it remains to be determined whether the traits of the two populations are genetically fixed. We conclude that O. navus is a euryphagous generalist predator which shows local specialisation on the locally abundant prey. PMID:23200575

  19. Almost a spider: a 305-million-year-old fossil arachnid and spider origins.

    PubMed

    Garwood, Russell J; Dunlop, Jason A; Selden, Paul A; Spencer, Alan R T; Atwood, Robert C; Vo, Nghia T; Drakopoulos, Michael

    2016-03-30

    Spiders are an important animal group, with a long history. Details of their origins remain limited, with little knowledge of their stem group, and no insights into the sequence of character acquisition during spider evolution. We describe a new fossil arachnid, Idmonarachne brasierigen. et sp. nov. from the Late Carboniferous (Stephanian,ca 305-299 Ma) of Montceau-les-Mines, France. It is three-dimensionally preserved within a siderite concretion, allowing both laboratory- and synchrotron-based phase-contrast computed tomography reconstruction. The latter is a first for siderite-hosted fossils and has allowed us to investigate fine anatomical details. Although distinctly spider-like in habitus, this remarkable fossil lacks a key diagnostic character of Araneae: spinnerets on the underside of the opisthosoma. It also lacks a flagelliform telson found in the recently recognized, spider-related, Devonian-Permian Uraraneida. Cladistic analysis resolves our new fossil as sister group to the spiders: the spider stem-group comprises the uraraneids and I. brasieri While we are unable to demonstrate the presence of spigots in this fossil, the recovered phylogeny suggests the earliest character to evolve on the spider stem-group is the secretion of silk. This would have been followed by the loss of a flagelliform telson, and then the ability to spin silk using spinnerets. This last innovation defines the true spiders, significantly post-dates the origins of silk, and may be a key to the group's success. The Montceau-les-Mines locality has previously yielded a mesothele spider (with spinnerets). Evidently, Late Palaeozoic spiders lived alongside Palaeozoic arachnid grades which approached the spider condition, but did not express the full suite of crown-group autapomorphies. PMID:27030415

  20. Almost a spider: a 305-million-year-old fossil arachnid and spider origins

    PubMed Central

    Garwood, Russell J.; Dunlop, Jason A.; Selden, Paul A.; Spencer, Alan R. T.; Atwood, Robert C.; Vo, Nghia T.; Drakopoulos, Michael

    2016-01-01

    Spiders are an important animal group, with a long history. Details of their origins remain limited, with little knowledge of their stem group, and no insights into the sequence of character acquisition during spider evolution. We describe a new fossil arachnid, Idmonarachne brasieri gen. et sp. nov. from the Late Carboniferous (Stephanian, ca 305–299 Ma) of Montceau-les-Mines, France. It is three-dimensionally preserved within a siderite concretion, allowing both laboratory- and synchrotron-based phase-contrast computed tomography reconstruction. The latter is a first for siderite-hosted fossils and has allowed us to investigate fine anatomical details. Although distinctly spider-like in habitus, this remarkable fossil lacks a key diagnostic character of Araneae: spinnerets on the underside of the opisthosoma. It also lacks a flagelliform telson found in the recently recognized, spider-related, Devonian–Permian Uraraneida. Cladistic analysis resolves our new fossil as sister group to the spiders: the spider stem-group comprises the uraraneids and I. brasieri. While we are unable to demonstrate the presence of spigots in this fossil, the recovered phylogeny suggests the earliest character to evolve on the spider stem-group is the secretion of silk. This would have been followed by the loss of a flagelliform telson, and then the ability to spin silk using spinnerets. This last innovation defines the true spiders, significantly post-dates the origins of silk, and may be a key to the group's success. The Montceau-les-Mines locality has previously yielded a mesothele spider (with spinnerets). Evidently, Late Palaeozoic spiders lived alongside Palaeozoic arachnid grades which approached the spider condition, but did not express the full suite of crown-group autapomorphies. PMID:27030415

  1. Almost a spider: a 305-million-year-old fossil arachnid and spider origins.

    PubMed

    Garwood, Russell J; Dunlop, Jason A; Selden, Paul A; Spencer, Alan R T; Atwood, Robert C; Vo, Nghia T; Drakopoulos, Michael

    2016-03-30

    Spiders are an important animal group, with a long history. Details of their origins remain limited, with little knowledge of their stem group, and no insights into the sequence of character acquisition during spider evolution. We describe a new fossil arachnid, Idmonarachne brasierigen. et sp. nov. from the Late Carboniferous (Stephanian,ca 305-299 Ma) of Montceau-les-Mines, France. It is three-dimensionally preserved within a siderite concretion, allowing both laboratory- and synchrotron-based phase-contrast computed tomography reconstruction. The latter is a first for siderite-hosted fossils and has allowed us to investigate fine anatomical details. Although distinctly spider-like in habitus, this remarkable fossil lacks a key diagnostic character of Araneae: spinnerets on the underside of the opisthosoma. It also lacks a flagelliform telson found in the recently recognized, spider-related, Devonian-Permian Uraraneida. Cladistic analysis resolves our new fossil as sister group to the spiders: the spider stem-group comprises the uraraneids and I. brasieri While we are unable to demonstrate the presence of spigots in this fossil, the recovered phylogeny suggests the earliest character to evolve on the spider stem-group is the secretion of silk. This would have been followed by the loss of a flagelliform telson, and then the ability to spin silk using spinnerets. This last innovation defines the true spiders, significantly post-dates the origins of silk, and may be a key to the group's success. The Montceau-les-Mines locality has previously yielded a mesothele spider (with spinnerets). Evidently, Late Palaeozoic spiders lived alongside Palaeozoic arachnid grades which approached the spider condition, but did not express the full suite of crown-group autapomorphies.

  2. SPECIALISED USE OF WORKING MEMORY BY PORTIA AFRICANA, A SPIDER-EATING SALTICID

    PubMed Central

    Jackson, Robert R.

    2013-01-01

    Using expectancy-violation methods, we investigated the role of working memory in the predatory strategy of Portia africana, a salticid spider from Kenya that preys by preference on other spiders. One of this predator’s tactics is to launch opportunistic leaping attacks on to other spiders in their webs. Focussing on this particular tactic, our experiments began with a test spider on a ramp facing a lure (dead prey-spider mounted on a cork disc) that could be reached by leaping. After the test spider faced the lure for 30 s, we blocked the test spider’s view of the lure by lowering an opaque shutter before the spider leapt. When the shutter was raised 90 s later, either the same lure came into view again (control) or a different lure came into view (experimental: different prey type in same orientation or same prey type in different orientation). We recorded attack frequency (number of test spiders that leapt at the lure) and attack latency (time elapsing between shutter being raised and spiders initiating a leap). Attack latencies in control trials were not significantly different from attack latencies in experimental trials, regardless of whether it was prey type or prey orientation that changed in the experimental trials. However, compared with test spiders in the no-change control trials, significantly fewer test spiders leapt when prey type changed. There was no significant effect on attack frequency when prey orientation changed. These findings suggest that this predator represents prey type independently of prey orientation. PMID:23982622

  3. Spider-Venom Peptides as Therapeutics

    PubMed Central

    Saez, Natalie J.; Senff, Sebastian; Jensen, Jonas E.; Er, Sing Yan; Herzig, Volker; Rash, Lachlan D.; King, Glenn F.

    2010-01-01

    Spiders are the most successful venomous animals and the most abundant terrestrial predators. Their remarkable success is due in large part to their ingenious exploitation of silk and the evolution of pharmacologically complex venoms that ensure rapid subjugation of prey. Most spider venoms are dominated by disulfide-rich peptides that typically have high affinity and specificity for particular subtypes of ion channels and receptors. Spider venoms are conservatively predicted to contain more than 10 million bioactive peptides, making them a valuable resource for drug discovery. Here we review the structure and pharmacology of spider-venom peptides that are being used as leads for the development of therapeutics against a wide range of pathophysiological conditions including cardiovascular disorders, chronic pain, inflammation, and erectile dysfunction. PMID:22069579

  4. Spider-venom peptides as therapeutics.

    PubMed

    Saez, Natalie J; Senff, Sebastian; Jensen, Jonas E; Er, Sing Yan; Herzig, Volker; Rash, Lachlan D; King, Glenn F

    2010-12-01

    Spiders are the most successful venomous animals and the most abundant terrestrial predators. Their remarkable success is due in large part to their ingenious exploitation of silk and the evolution of pharmacologically complex venoms that ensure rapid subjugation of prey. Most spider venoms are dominated by disulfide-rich peptides that typically have high affinity and specificity for particular subtypes of ion channels and receptors. Spider venoms are conservatively predicted to contain more than 10 million bioactive peptides, making them a valuable resource for drug discovery. Here we review the structure and pharmacology of spider-venom peptides that are being used as leads for the development of therapeutics against a wide range of pathophysiological conditions including cardiovascular disorders, chronic pain, inflammation, and erectile dysfunction.

  5. Modelling Crop Biocontrol by Wanderer Spiders

    NASA Astrophysics Data System (ADS)

    Venturino, Ezio; Ghersi, Andrea

    2008-09-01

    We study mathematically the effects some spiders populations have on insects living in and near agroecosystems, where woods and vineyards alternate in the landscape as in the Alta Langa, Piemonte, NW Italy.

  6. Two-step phase-shifting SPIDER

    NASA Astrophysics Data System (ADS)

    Zheng, Shuiqin; Cai, Yi; Pan, Xinjian; Zeng, Xuanke; Li, Jingzhen; Li, Ying; Zhu, Tianlong; Lin, Qinggang; Xu, Shixiang

    2016-09-01

    Comprehensive characterization of ultrafast optical field is critical for ultrashort pulse generation and its application. This paper combines two-step phase-shifting (TSPS) into the spectral phase interferometry for direct electric-field reconstruction (SPIDER) to improve the reconstruction of ultrafast optical-fields. This novel SPIDER can remove experimentally the dc portion occurring in traditional SPIDER method by recording two spectral interferograms with π phase-shifting. As a result, the reconstructed results are much less disturbed by the time delay between the test pulse replicas and the temporal widths of the filter window, thus more reliable. What is more, this SPIDER can work efficiently even the time delay is so small or the measured bandwidth is so narrow that strong overlap happens between the dc and ac portions, which allows it to be able to characterize the test pulses with complicated temporal/spectral structures or narrow bandwidths.

  7. Two-step phase-shifting SPIDER

    PubMed Central

    Zheng, Shuiqin; Cai, Yi; Pan, Xinjian; Zeng, Xuanke; Li, Jingzhen; Li, Ying; Zhu, Tianlong; Lin, Qinggang; Xu, Shixiang

    2016-01-01

    Comprehensive characterization of ultrafast optical field is critical for ultrashort pulse generation and its application. This paper combines two-step phase-shifting (TSPS) into the spectral phase interferometry for direct electric-field reconstruction (SPIDER) to improve the reconstruction of ultrafast optical-fields. This novel SPIDER can remove experimentally the dc portion occurring in traditional SPIDER method by recording two spectral interferograms with π phase-shifting. As a result, the reconstructed results are much less disturbed by the time delay between the test pulse replicas and the temporal widths of the filter window, thus more reliable. What is more, this SPIDER can work efficiently even the time delay is so small or the measured bandwidth is so narrow that strong overlap happens between the dc and ac portions, which allows it to be able to characterize the test pulses with complicated temporal/spectral structures or narrow bandwidths. PMID:27666528

  8. Apoptosis and biochemical biomarkers of stress in spiders from industrially polluted areas exposed to high temperature and dimethoate.

    PubMed

    Wilczek, Grazyna

    2005-06-01

    The aim of this study was to evaluate the relations between apoptosis and the activity of antioxidant enzymes (superoxide dismutase; catalase) and quantitative changes in stress protein positive cells (Hsp70; metallothionein) in midgut glands of funnel web spiders Agelena labyrinthica (Agelenidae) and wolf spiders Pardosa lugubris (Lycosidae) exposed to high temperature and pesticide under laboratory conditions. The spiders were collected from two meadow ecosystems differently polluted with metals (Olkusz and Pilica, southern Poland). Under stress conditions, P. lugubris had fewer apoptotic cells in the midgut glands than A. labyrinthica. In P. lugubris from both sites, the observed increase in the percentage of metallothionein and Hsp70-positive cells, simultaneous with intensification of superoxide dismutase and catalase activity, suggests an anti-apoptotic function of those proteins in representatives of wandering spiders. In the midgut glands of A. labyrinthica, heat shock and dimethoate increased the number of Annexin V-positive cells as well as the amounts of mitochondria with low transmembrane potential (DeltaPsi(m)) versus the control. The changes in the percentage of MT- and Hsp70-positive cells in funnel web spiders were less than in wolf spiders. The absence of change in SOD and CAT activity in A. labyrinthica shows that the participation of those enzymes in antioxidant reactions is minimal in this species.

  9. Mites parasitic on Australasian and African spiders found in the pet trade; a redescription of Ljunghia pulleinei Womersley.

    PubMed

    Masan, Peter; Simpson, Christopher; Perotti, M Alejandra; Braig, Henk R

    2012-01-01

    Parasitic mites associated with spiders are spreading world-wide through the trade in tarantulas and other pet species. Ljunghia pulleinei Womersley, a mesostigmatic laelapid mite originally found in association with the mygalomorph spider Selenocosmia stirlingi Hogg (Theraphosidae) in Australia, is redescribed and illustrated on the basis of specimens from the African theraphosid spider Pterinochilus chordatus (Gerstäcker) kept in captivity in the British Isles (Wales). The mite is known from older original descriptions of Womersley in 1956; the subsequent redescription of Domrow in 1975 seems to be questionable in conspecificity of treated specimens with the type material. Some inconsistencies in both descriptions are recognised here as intraspecific variability of the studied specimens. The genus Arachnyssus Ma, with species A. guangxiensis (type) and A. huwenae, is not considered to be a valid genus, and is included in synonymy with Ljunghia Oudemans. A new key to world species of the genus Ljunghia is provided.

  10. Recombinant DNA production of spider silk proteins

    PubMed Central

    Tokareva, Olena; Michalczechen-Lacerda, Valquíria A; Rech, Elíbio L; Kaplan, David L

    2013-01-01

    Spider dragline silk is considered to be the toughest biopolymer on Earth due to an extraordinary combination of strength and elasticity. Moreover, silks are biocompatible and biodegradable protein-based materials. Recent advances in genetic engineering make it possible to produce recombinant silks in heterologous hosts, opening up opportunities for large-scale production of recombinant silks for various biomedical and material science applications. We review the current strategies to produce recombinant spider silks. PMID:24119078

  11. Variation in Protein Intake Induces Variation in Spider Silk Expression

    PubMed Central

    Blamires, Sean J.; Wu, Chun-Lin; Tso, I-Min

    2012-01-01

    Background It is energetically expensive to synthesize certain amino acids. The proteins (spidroins) of spider major ampullate (MA) silk, MaSp1 and MaSp2, differ in amino acid composition. Glutamine and proline are prevalent in MaSp2 and are expensive to synthesize. Since most orb web spiders express high proline silk they might preferentially attain the amino acids needed for silk from food and shift toward expressing more MaSp1 in their MA silk when starved. Methodology/Principal Findings We fed three spiders; Argiope aetherea, Cyrtophora moluccensis and Leucauge blanda, high protein, low protein or no protein solutions. A. aetherea and L. blanda MA silks are high in proline, while C. moluccesnsis MA silks are low in proline. After 10 days of feeding we determined the amino acid compositions and mechanical properties of each species' MA silk and compared them between species and treatments with pre-treatment samples, accounting for ancestry. We found that the proline and glutamine of A. aetherea and L. blanda silks were affected by protein intake; significantly decreasing under the low and no protein intake treatments. Glutmaine composition in C. moluccensis silk was likewise affected by protein intake. However, the composition of proline in their MA silk was not significantly affected by protein intake. Conclusions Our results suggest that protein limitation induces a shift toward different silk proteins with lower glutamine and/or proline content. Contradictions to the MaSp model lie in the findings that C. moluccensis MA silks did not experience a significant reduction in proline and A. aetherea did not experience a significant reduction in serine on low/no protein. The mechanical properties of the silks could not be explained by a MaSp1 expressional shift. Factors other than MaSp expression, such as the expression of spidroin-like orthologues, may impact on silk amino acid composition and spinning and glandular processes may impact mechanics. PMID:22363691

  12. The Effects of Alcohol on Spiders: What Happens to Web Construction after Spiders Consume Alcohol?

    ERIC Educational Resources Information Center

    Cross, Victor E.

    2006-01-01

    In the high school experiment reported in this paper, spiders were provided w