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Sample records for orbweaving spider species

  1. 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.

  2. Effects of grassland succession on communities of orb-weaving spiders.

    PubMed

    Richardson, M L; Hanks, L M

    2009-12-01

    Native grasslands are among the most imperiled of the North American ecosystems, but abandoned agricultural areas may provide suitable habitat for animal taxa that are endemic to grasslands. We studied how species diversity of orb-weaving spiders was influenced by secondary succession of a grassland plant community by monitoring the abundance and species diversity in study plots that were cultivated at 6-yr intervals and left uncultivated in the interim. We tested the hypothesis that local abundance and species diversity of spiders would be positively associated with time since cultivation because plant communities in older habitats would be more architecturally complex. Local abundance of spiders in general was not associated with time since cultivation, but abundance of Mangora gibberosa (Hentz) was positively associated with the abundance of perennial plants. Species richness and diversity of spiders also were positively associated with the abundance of perennial plants and reached a threshold a few years after cultivation. Species diversity of orb-weaving spiders seems to be strongly influenced by species composition of the plant community. Therefore, effective restoration of the structure and function of endemic communities of orb-weaving spiders may depend on preserving endemic grassland plant communities.

  3. 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

    2016-05-17

    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.

  4. 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.

  5. 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

  6. 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.

  7. The male of the orb-weaving spider Plebs mitratus (Simon, 1895) and a redescription of the female (Araneae, Araneidae).

    PubMed

    Paul, Jimmy; Sankaran, Pradeep M; Joseph, Mathew M; Sebastian, Pothalil A

    2016-10-28

    The orb-weaving spider genus Plebs Joseph & Framenau, 2012 currently has only two representatives in India: Plebs himalayaensis (Tikader, 1975) from the Himalayas and Plebs mitratus (Simon, 1895) from the Nilgiris and Anamudi Shola National Park (World Spider Catalog 2016), both are found in high altitude mountainous habitats (Joseph & Framenau 2012). Both species were known only from females (World Spider Catalog 2016), although Sherriffs (1918, 1919) provided a description of an immature male of P. mitratus. In the present paper, we provide the first description of the adult male of P. mitratus, together with the detailed redescription of its female demonstrating considerable intraspecific variation.

  8. 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.

  9. 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.

  10. 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

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

    PubMed Central

    Penney, David; Ortuño, Vicente M

    2006-01-01

    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 Álava, 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. PMID:17148427

  12. Colourful orb-weaving spiders, Nephila pilipes, through a bee's eyes.

    PubMed

    Tso, I-Min; Lin, Chih-Wei; Yang, En-Cheng

    2004-07-01

    Many orb-weaving spiders in the tropics forage in open sites during the day and some of them have both bright and dark colourations. The conspicuous UV-reflective colour markings of these spiders have been reported to be attractive to visually oriented prey and thus could increase the spiders' foraging success. Using a combination of field and laboratory studies, we examine whether or not the body colouration of orb-weaving spiders exhibits optical properties that are attractive to insect prey from the viewpoint of insect visual physiology. We compared the prey interception rates and colour contrasts of the typical and melanic morphs of the giant wood spider, Nephila pilipes. Results of the field study showed that the typical morph caught significantly more insects than the melanic morph. Colour contrasts calculated from spectral reflectances of the background and body surface of spiders showed that the brightly coloured body parts of the typical morph exhibited rather high values, but those of the dark body parts were below the discrimination threshold. The differential colour contrasts of body parts generated a visual signal unlike that of a spider but rather like certain forms of food resources. On the other hand, the melanic morphs did not have bright colouration and the colour contrasts of every part of the body were significantly higher than the threshold, making the contour of spiders quite clear to bees.

  13. 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.

  14. Proximate mechanism of behavioral manipulation of an orb-weaver spider host by a parasitoid wasp

    PubMed Central

    Gonzaga, Marcelo Oliveira; de Oliveira, Leandro Licursi; Sperber, Carlos Frankl

    2017-01-01

    Some ichneumonid wasps induce modifications in the web building behavior of their spider hosts to produce resistant “cocoon” webs. These structures hold and protect the wasp’s cocoon during pupa development. The mechanism responsible for host manipulation probably involves the inoculation of psychotropic chemicals by the parasitoid larva during a specific developmental period. Recent studies indicate that some spiders build cocoon webs similar to those normally built immediately before ecdysis, suggesting that this substance might be a molting hormone or a precursor chemical of this hormone. Here, we report that Cyclosa spider species exhibiting modified behavior presented higher 20-OH-ecdysone levels than parasitized spiders acting normally or unparasitized individuals. We suggest that the lack of control that spiders have when constructing modified webs can be triggered by anachronic activation of ecdysis. PMID:28158280

  15. Proximate mechanism of behavioral manipulation of an orb-weaver spider host by a parasitoid wasp.

    PubMed

    Kloss, Thiago Gechel; Gonzaga, Marcelo Oliveira; de Oliveira, Leandro Licursi; Sperber, Carlos Frankl

    2017-01-01

    Some ichneumonid wasps induce modifications in the web building behavior of their spider hosts to produce resistant "cocoon" webs. These structures hold and protect the wasp's cocoon during pupa development. The mechanism responsible for host manipulation probably involves the inoculation of psychotropic chemicals by the parasitoid larva during a specific developmental period. Recent studies indicate that some spiders build cocoon webs similar to those normally built immediately before ecdysis, suggesting that this substance might be a molting hormone or a precursor chemical of this hormone. Here, we report that Cyclosa spider species exhibiting modified behavior presented higher 20-OH-ecdysone levels than parasitized spiders acting normally or unparasitized individuals. We suggest that the lack of control that spiders have when constructing modified webs can be triggered by anachronic activation of ecdysis.

  16. Mercury bioaccumulation, speciation, and influence on web structure in orb-weaving spiders from a forested watershed.

    PubMed

    Wyman, Katherine E; Rodenhouse, Nicholas L; Bank, Michael S

    2011-08-01

    Atmospheric deposition is an important source of Hg in remote terrestrial ecosystems of northeastern North America. As high-level invertebrate consumers, orb-weaving spiders (family Araneidae) are excellent subjects for studying the impact of sublethal levels of Hg on forest animals because their webs provide snapshots of behavior and neurological function. Spiders of the diadematus group of the genus Araneus were collected from the Jeffers Brook watershed in the White Mountain National Forest, New Hampshire (USA), and analyzed for Hg content. Webs were photographed and measured to test for correlations between Hg body burden and web structure. Collected spiders contained concentrations of total Hg averaging 44.7 ± 10.0 ng/g Hg (wet mass; mean ± standard deviation), with 37 ± 6% of the total Hg present in the methylmercury form. Mercury loads were likely accumulated through diet (potential prey items contained an average of 43% of the Hg load in collected spiders) and possibly web ingestion. The present study found no direct evidence that the web structure-and thus the prey-capture ability-of spiders in the study area was affected by their Hg body burden.

  17. Visualization of the spatial and spectral signals of orb-weaving spiders, Nephila pilipes, through the eyes of a honeybee.

    PubMed

    Chiao, Chuan-Chin; Wu, Wen-Yen; Chen, Sheng-Hui; Yang, En-Cheng

    2009-07-01

    It is well known that the honeybee has good color vision. However, the spectral range in which the bee can see is different from that of the human eye. To study how bees view their world of colors, one has to see through the eyes of the bee, not the eyes of a human. A conventional way to examine the color signals that animals can detect is to measure the surface reflectance spectra and compute the quantum catches of each photoreceptor type based on its known spectral sensitivity. Color signal and color contrast are then determined from the loci of these quantum catches in the color space. While the point-by-point measurements of the reflectance spectra using a standard spectrometer have yielded a significant amount of data for analyzing color signals, the lack of spatial information and low sampling efficiency constrain their applications. Using a special filter coating technique, a set of filters with transmission spectra that were closely matched to the bee's sensitivity spectra of three photoreceptor types (UV, blue, and green) was custom made. By placing these filters in front of a UV/VIS-sensitive CCD camera and acquiring images sequentially, we could collect images of a bee's receptor with only three shots. This allowed a direct visualization of how bees view their world in a pseudo-color RGB display. With this imaging system, spatial and spectral signals of the orb-weaving spider, Nephila pilipes, were recorded, and color contrast images corresponding to the bee's spatial resolution were constructed and analyzed. The result not only confirmed that the color markings of N. pilipes are of high chromatic contrast to the eyes of a bee, but it also indicated that the spatial arrangement of these markings resemble flower patterns which may attract bees to visit them. Thus, it is likely that the orb-weaving spider (N. pilipes) deploys a similar strategy to that of the Australian crab spider (Thomisus spectabilis) to exploit the bee's pre-existing preference for

  18. Structure-activity relationships of pyrrolizidine alkaloids in insect chemical defense against the orb-weaving spider Nephila clavipes.

    PubMed

    Silva, Karina Lucas; Trigo, José Roberto

    2002-04-01

    Pyrrolizidine alkaloids (PAs) are known to protect Arctiidae moths and Danainae and Ithomiinae butterflies against the orb-weaving spider Nephila clavipes (Araneae, Araneidae, Tetragnathinae), which liberates adults of these insects unharmed from its web. We tested against this spider the role of eight PAs and one derived structure [an 89:11 mixture of the 12-membered macrocyclic diester free base integerrimine and senecionine and the respective N-oxide; two hydrolysis products from this mixture (the necine base retronecine, its respective N-oxide, and a mixture of integerriminic and senecionic necic acids); the 12-membered macrocyclic senkirkine; the 9-O-monoester free base senecioylretronecine and its respective N-oxide; and the 9-O-monoester free base callimorphine (a PA biosynthesized only by insects from retronecine)]. The mixture integerrimine-senecionine N-oxide seems to be more active than the respective free base [LibD50 (liberation dose 50) = 0.042 and 0.153 microg/dry weight of prey, respectively], but the difference in activity between the N-oxide and free base of the 9-O-monoester senecioylretronecine was slight (LibD50 = 0.167 and 0.104, respectively). Senkirkine, an otonecine base PA that does not form N-oxide and is not found in insects, was the less active, showing the highest LibD50 (0.354). The difference in antipredator activity between N-oxides and free bases from macrocyclic diesters and monoesters may be correlated with physicochemical properties of these molecules in interaction with the Nephila receptors. For the active structures, there was a significant correlation between dosage and antipredator activity. Both forms of retronecine and a necic acid mixture were inactive, supporting the hypothesis that PAs biosynthesized by insects from retronecine were originally produced and stored in order to optimize chemical defense. Comparison of dose/activity data with reported amounts of PAs in butterflies suggested that, in general, PA

  19. Dynamic optimization over infinite-time horizon: web-building strategy in an orb-weaving spider as a case study.

    PubMed

    Venner, Samuel; Chadès, Iadine; Bel-Venner, Marie-Claude; Pasquet, Alain; Charpillet, François; Leborgne, Raymond

    2006-08-21

    Dynamic state-dependent models have been widely developed since 1990s for solving questions in evolutionary ecology. Up to now, these models were mainly run over finite-time horizon. However, for many biological questions an infinite-time horizon perspective could be more appropriate, especially when the end of the modeled period is state- rather than time-dependent. Despite this approach is widely used in the field of economics and operational research, thus far no work has been providing biologists with a general method to solve infinite-time horizon problems. Here we present such a method, through the exhaustive description of an algorithm that we implement to determine the strategy an organism should follow to reach a particular state as fast as possible while limiting mortality risk. To illustrate that method we explored web-building behavior in an orb-weaving spider. How are adult females predicted to build their successive webs to gain energy, grow, and lay their first clutch as fast as possible, without suffering from either predation or starvation? From this example, we first show how an optimal strategy over infinite-time horizon can be processed and selected. Second, we analyse variations of the optimal web-building strategy along with the spider's body weight and predation risk during web building. Our model yields two main predictions: (1) spiders reduce their web size as they are gaining weight due to body-mass-dependent cost of web-building behavior, and (2) this reduction in web size starts at lower weight under higher predation risk.

  20. 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

  1. 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.

  2. 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.

  3. 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

  4. Nephila clavipes spiders (Araneae: Nephilidae) keep track of captured prey counts: testing for a sense of numerosity in an orb-weaver.

    PubMed

    Rodríguez, Rafael L; Briceño, R D; Briceño-Aguilar, Eduardo; Höbel, Gerlinde

    2015-01-01

    Nephila clavipes golden orb-web spiders accumulate prey larders on their webs and search for them if they are removed from their web. Spiders that lose larger larders (i.e., spiders that lose larders consisting of more prey items) search for longer intervals, indicating that the spiders form memories of the size of the prey larders they have accumulated, and use those memories to regulate recovery efforts when the larders are pilfered. Here, we ask whether the spiders represent prey counts (i.e., numerosity) or a continuous integration of prey quantity (mass) in their memories. We manipulated larder sizes in treatments that varied in either prey size or prey numbers but were equivalent in total prey quantity (mass). We then removed the larders to elicit searching and used the spiders' searching behavior as an assay of their representations in memory. Searching increased with prey quantity (larder size) and did so more steeply with higher prey counts than with single prey of larger sizes. Thus, Nephila spiders seem to track prey quantity in two ways, but to attend more to prey numerosity. We discuss alternatives for continuous accumulator mechanisms that remain to be tested against the numerosity hypothesis, and the evolutionary and adaptive significance of evidence suggestive of numerosity in a sit-and-wait invertebrate predator.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. The venomous secrets of the web droplets from the viscid spiral of the orb-weaver spider Nephila clavipes (Araneae, Tetragnatidae).

    PubMed

    Salles, Heliana C; Volsi, Evelyn Cristina F R; Marques, Maurício R; Souza, Bibiana M; dos Santos, Lucilene D; Tormena, Cláudio F; Mendes, Maria A; Palma, Mario S

    2006-07-01

    The capture web of N. clavipes presents viscous droplets, which play important roles in web mechanics and prey capture. By using scanning and transmission electron microscopy, it was demonstrated that the web droplets are constituted of different chemical environments, provided by the existence both of an aqueous and a lipid layer, which, in turn, present a suspension of tenths of vesicles containing polypeptides and/or lipids. GC/EI-MS Analysis of the contents of these vesicles led to the identification of some saturated fatty acids, such as decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, octadecanoic acid, and icosanoic acid, while other components were unsaturated fatty acids, such as (Z)-tetradec-9-enoic acid, (Z)-octadec-9-enoic acid, and (Z)-icosa-11-enoic acid; and polyunsaturated fatty acids like (9Z,12Z)-octadeca-9,12-dienoic acid, (9Z,12Z,15Z)-octadeca-9,12,15-trienoic acid, and (11Z,14Z)-icosa-11,14-dienoic acid. Toxic proteins such as calcium-activated proteinase and metalloproteinase jararhagin-like precursor were also identified by using a proteomic approach, indicating the possible involvement of these enzymes in the pre-digestion of spiders' preys web-captured. Apparently, the mixture of fatty acids are relatively toxic to insects by topical application (LD50 64.3+/-7.6 ng mg(-1) honeybee), while the proteins alone present no topical effect; however, when injected into the prey-insects, these proteins presented a moderate toxicity (LD50 40.3+/-4.8 ng mg(-1) honeybee); the mixture of fatty acids and proteins is very toxic to the preys captured by the web droplets of the viscid spiral of Nephila clavipes when topically applied on them (LD50 14.3+/-1.8 ng mg(-1) honeybee).

  10. 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.

  11. 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

  12. Constraints on the adhesion of viscous threads spun by orb-weaving spiders: the tensile strength of glycoprotein glue exceeds its adhesion.

    PubMed

    Opell, Brent D; Schwend, Harold S; Vito, Stephen T

    2011-07-01

    In this study we tested the hypothesis that a viscous thread releases its hold on a surface because its glycoprotein glue pulls from the surface and not because its elongating droplets break near their attachment to the surface. We compared the values obtained when three species' viscous threads adhered to four smooth surfaces, which differed in their total surface energy and in the proportions of their dispersion and polar energy components. Although water comprised 43-70% of the volume of these viscous droplets, only the dispersion surface energies of test materials and not their polar surface energies impacted thread adhesion. These results support the droplet pull-off hypothesis and are consistent with a previous finding that capillary force contributes little to thread adhesion. Just as a viscous thread's stickiness is constrained by the tensile strength of its supporting axial fibers, our findings suggest that glycoprotein adhesion is constrained by glycoprotein tensile strength.

  13. Piriform spider silk sequences reveal unique repetitive elements.

    PubMed

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

    2010-11-08

    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.

  14. 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.

  15. 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

  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. Sexual size dimorphism predicts the frequency of sexual cannibalism within and among species of spiders.

    PubMed

    Wilder, Shawn M; Rypstra, Ann L

    2008-09-01

    Sexual cannibalism varies widely among spiders, but no general evolutionary hypothesis has emerged to explain its distribution across taxa. Sexual size dimorphism (SSD) also varies widely among spiders and could affect the vulnerability of males to cannibalistic attacks by females. We tested for a relationship between SSD and sexual cannibalism within and among species of spiders, using a broad taxonomic data set. For most species, cannibalism was more likely when males were much smaller than females. In addition, using phylogenetically controlled and uncontrolled analyses, there was a strong positive relationship between average SSD of a species and the frequency of sexual cannibalism. This is the first evidence that the degree of size difference between males and females is related to the phylogenetic distribution of sexual cannibalism among a broad range of spiders.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. A new species of the spider genus Taczanowskia (Araneae, Araneidae) from Mexico.

    PubMed

    Ibarra-Núñez, Guillermo

    2013-01-01

    A new species of the spider genus Taczanowskia, T. gustavoi n. sp. is described from Chiapas, Mexico. This finding extends the distribution of Taczanowskia species, hitherto known only from South America to Southern Mexico. T. gustavoi n. sp. can be differentiated from all other species in this genus by having more than six tubercles in the dorsum of its opisthosoma. This species is included in an earlier determination key for all previously known Taczanowskia species.

  3. 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...

  4. 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

  5. Inferring Species Trees from Gene Trees in a Radiation of California Trapdoor Spiders (Araneae, Antrodiaetidae, Aliatypus)

    PubMed Central

    Satler, Jordan D.; Starrett, James; Hayashi, Cheryl Y.; Hedin, Marshal

    2011-01-01

    Background The California Floristic Province is a biodiversity hotspot, reflecting a complex geologic history, strong selective gradients, and a heterogeneous landscape. These factors have led to high endemic diversity across many lifeforms within this region, including the richest diversity of mygalomorph spiders (tarantulas, trapdoor spiders, and kin) in North America. The trapdoor spider genus Aliatypus encompasses twelve described species, eleven of which are endemic to California. Several Aliatypus species show disjunct distributional patterns in California (some are found on both sides of the vast Central Valley), and the genus as a whole occupies an impressive variety of habitats. Methodology/Principal Findings We collected specimens from 89 populations representing all described species. DNA sequence data were collected from seven gene regions, including two newly developed for spider systematics. Bayesian inference (in individual gene tree and species tree approaches) recovered a general “3 clade” structure for the genus (A. gulosus, californicus group, erebus group), with three other phylogenetically isolated species differing slightly in position across different phylogenetic analyses. Because of extremely high intraspecific divergences in mitochondrial COI sequences, the relatively slowly evolving 28S rRNA gene was found to be more useful than mitochondrial data for identification of morphologically indistinguishable immatures. For multiple species spanning the Central Valley, explicit hypothesis testing suggests a lack of monophyly for regional populations (e.g., western Coast Range populations). Phylogenetic evidence clearly shows that syntopy is restricted to distant phylogenetic relatives, consistent with ecological niche conservatism. Conclusions/Significance This study provides fundamental insight into a radiation of trapdoor spiders found in the biodiversity hotspot of California. Species relationships are clarified and undescribed lineages

  6. 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.

  7. 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.

  8. Inter-specific sequence conservation and intra-individual sequence variation in a spider silk gene.

    PubMed

    Tai, Pei-Ling; Hwang, Guang-Yuh; Tso, I-Min

    2004-10-01

    Currently, studies on major ampullate spidroin 1 (MaSp1) genes of non-orb weaving spiders are few, and it is not clear whether genes of these organisms exhibit the same characteristics as those of orb-weavers. In addition, many studies have proposed that MaSp1 might be a single gene with allelic variants, but supporting evidence is still lacking. In this study, we compared partial DNA and amino acid sequences of MaSp1 cloned from different spider guilds. We also cloned partial MaSp1 sequences from genomic DNA and cDNA of the same individuals of spiders using the same primer combination to see if different molecular forms existed. In the repetitive region of partial MaSp1 sequences obtained, GGX, GA and poly-A motifs were present in all Araneomorphae and Mygalomorpae species examined. An extreme similarity in MaSp1 non-repetitive portions was found in sequences of ecribellate, cribellate and Mygalomorphae web-builders and such a result suggested that this sequence might exhibit an important function. A comparison of sequences amplified from the same individual showed that substitutions in amino acids occurred in both repetitive and non-repetitive regions, with a much higher variation in the former. These results suggest that the MaSp1 of Araneomorphae spiders exhibits several forms in an individual spider and it might be either a multiple gene or a single gene with a multiple exon/intron organization.

  9. 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.

  10. Loxosceles niedeguidonae (Araneae, Sicariidae) a new species of brown spider from Brazilian semi-arid region

    PubMed Central

    Gonçalves-de-Andrade, Rute Maria; Bertani, Rogério; Nagahama, Roberto Hiroaki; Barbosa, Maria Fatima Ribeiro

    2012-01-01

    Abstract A new species of recluse spider, Loxosceles niedeguidonae sp. n., is described from the Parque Nacional Serra da Capivara, State of Piauí, Brazil. This is the first endemic species described from Brazilian semi-arid environment. The species is included in gaucho group of Gertsch (1967) due to its spermathecal shape and is considered close to Loxosceles chapadensis Bertani, Fukushima & Nagahama, 2010 by the unusual long male palpal tibia, a character not common for species of this group. An updated key for Loxosceles species of gaucho group is presented. PMID:22451789

  11. 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

    2014-08-04

    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.

  12. Spider bite.

    PubMed

    Isbister, Geoffrey K; Fan, Hui Wen

    2011-12-10

    Spiders are a source of intrigue and fear, and several myths exist about their medical effects. Many people believe that bites from various spider species cause necrotic ulceration, despite evidence that most suspected cases of necrotic arachnidism are caused by something other than a spider bite. Latrodectism and loxoscelism are the most important clinical syndromes resulting from spider bite. Latrodectism results from bites by widow spiders (Latrodectus spp) and causes local, regional, or generalised pain associated with non-specific symptoms and autonomic effects. Loxoscelism is caused by Loxosceles spp, and the cutaneous form manifests as pain and erythema that can develop into a necrotic ulcer. Systemic loxoscelism is characterised by intravascular haemolysis and renal failure on occasion. Other important spiders include the Australian funnel-web spider (Atrax spp and Hadronyche spp) and the armed spider (Phoneutria spp) from Brazil. Antivenoms are an important treatment for spider envenomation but have been less successful than have those for snake envenomation, with concerns about their effectiveness for both latrodectism and loxoscelism.

  13. A New Assay for the Detection of Loxosceles Species (Brown Recluse) Spider Venom

    PubMed Central

    Gomez, Hernan F.; Krywko, Diann M.; Stoecker, William V.

    2011-01-01

    Study objective Dermal lesions from unrelated arthropod species and medical causes appear similar to Loxosceles species (brown recluse spider) bites. This may result in delayed diagnosis and treatment. We developed a sensitive Loxosceles species venom enzyme-linked immunosorbent assay (ELISA) and characterized the specificity of the assay by evaluating antigenic cross-reactivity from a variety of North American arthropod venoms. Methods North American arthropod (14 spiders, 2 scorpions, and 1 bee) venoms were studied. Three venom amounts (diluted in 100 μL of ELISA buffer) were assayed: 16,000 ng, 2,000 ng, and 40 ng. The latter quantity was selected because this is the observed maximum amount of venom we detect when inoculating dermis with amounts likely to be deposited by a spider bite. The larger venom amounts are overwhelming quantities designed to test the limits of the assay for arthropod venom cross-reactivity. Similar amounts of Loxosceles species venom and bovine albumin served as positive and negative controls, respectively. Results At the lowest amount of venom tested (40 ng), the ELISA detected only the Loxosceles species positive control. When 2,000 ng was assayed, only Scytodes fusca and Kukulcania hibernalis arachnid venoms (in addition to Loxosceles species) cross-reacted to the assay. Finally, at 16,000 ng, the ELISA assay modestly detected Diguetia canities, Heteropoda venatoria, Tegenaria agrestis, Plectreurys tristes, Dolomedes tenebrosus, and Hadrurus arizonensis arachnid venoms. Conclusion Cross-reactivity was observed in 8 of 17 North American arthropod venoms when large venom amounts were assayed with a Loxosceles species ELISA. By using a relevant quantity of venom, 40 ng, the assay was specific for Loxosceles species venom. The venom specificity of the ELISA may allow clinical application in Loxosceles species endemic regions of North America. PMID:11973553

  14. Lyriform slit sense organs on the pedipalps and spinnerets of spiders.

    PubMed

    Patil, Bhavani; Prabhu, Suphala; Rajashekhar, K P

    2006-03-01

    Lyriform slits sense organs (LSSO) are a precise assembly of stress detecting cuticular slit sensilla found on the appendages of arachnids. While these structures on the legs of the wandering spider Cupennius salei are well studied in terms of morphology, function and contribution to behaviour, their distribution on pedipalps and spinnerets of spiders is not well explored. A study was therefore carried out to observe the distribution of LSSO on pedipalps and spinnerets of some spider species. Haplogyne spiders belonging to family Pholcidae have a simple complement of LSSOs represented by one or two LSSOs on their femur. The entelegyne spiders possess a complex assembly of LSSOs on the distal segments of their pedipalps. Various types of LSSOs are found on the pedipalps indicating a capacity for analysis of complex cuticular stress. It is suggested that the complexity of LSSOs on pedipalps of entel-egyne spiders relates to courtship and spermatophore transfer and may help in reproductive isolation. Lack of LSSOs on the distal segments of pedipalps leads us to infer that unlike legs, pedipalps are less likely to receive vibratory input through their distal segments. Spinnerets have a relatively simple complement of LSSOs. One LSSO is found only on anterior spinnerets and it is a common feature observed among spiders, irrespective of the variations in web building behaviour. The orb-weaving araneid Argiope pulchella, however, has two LSSOs on the anterior spinneret. As non-web builders and orb weavers do not differ markedly in terms of LSSOs on the spinnerets and LSSOs are simple in nature (type A), it is likely that spinning and weaving are not largely regulated by sensory input from LSSOs on the spinnerets.

  15. Co-occurrence of ecologically equivalent cryptic species of spider wasps

    PubMed Central

    Kurushima, Hiroaki; Kim, Jeong-Kyu; Kim, Jong-Kuk; Nishimoto, Yutaka; Sayama, Katsuhiko; Kato, Manabu; Watanabe, Kenta; Hasegawa, Eisuke; Roff, Derek A.; Shimizu, Akira

    2016-01-01

    Many cryptic species have been discovered in various taxonomic groups based on molecular phylogenetic analyses and mating experiments. Some sympatric cryptic species share equivalent resources, which contradicts the competitive exclusion principle. Two major theories have been proposed to explain the apparent lack of competitive exclusion, i.e. niche-based coexistence and neutral model, but a conclusive explanation is lacking. Here, we report the co-occurrence of cryptic spider wasp species appearing to be ecologically equivalent. Molecular phylogenetic analyses and mating experiments revealed that three phylogenetically closely related species are found sympatrically in Japan. These species share the same resources for larval food, and two of the species have the same niche for nesting sites, indicating a lack of competitive exclusion. This evidence may suggest that ecologically equivalent species can co-occur stably if their shared resources are sufficiently abundant that they cannot be over-exploited. PMID:27853590

  16. 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.

  17. Latrodectism: variations in clinical manifestations provoked by Latrodectus species of spiders.

    PubMed

    Maretić, Z

    1983-01-01

    The clinical picture caused by the bite of Latrodectus spp. is described, including the patient's general condition with agonizing pains, cramps, spasms, motor unrest, boardlike abdomen, "facies latrodectismica", sweating, oliguria, hypertension, anxiety, mental excitation and an extended convalescence. The notorious biters are mainly L. mactans, L. variolus, L. hesperus, L. tredecimguttatus, L. hasselti, L. indistinctus and L. menavodi, all of which appear to provoke somewhat similar clinical pictures. For some species, however, there is limited data and for the toxicity of some spiders, such as L. rhodesiensis, no data are available, However, it would appear that the clinical manifestations of the venom are similar in all species.

  18. 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

  19. Nuptial gifts and sexual behavior in two species of spider (Araneae, Trechaleidae, Paratrechalea)

    NASA Astrophysics Data System (ADS)

    Costa-Schmidt, Luiz Ernesto; Carico, James Edwin; de Araújo, Aldo Mellender

    2008-08-01

    Male delivering of a prey packed in silk as a nuptial gift is rare in spiders and restricted until now to Pisauridae. Here, we describe this behavioral pattern found in two Trechaleidae species, Paratrechalea azul Carico 2005, and Paratrechalea ornata (Mello-Leitão 1943), mainly based on field observations. We observed the following steps of sexual behavior: sperm induction, nuptial gift construction, mate searching, pre-copulatory courtship, copulation, and copulatory ending. In this group, a nuptial gift consists of a prey wrapped in silk, which appears as a white rounded shape. The male carries his nuptial gift in his chelicerae while searching for a female. When he finds a female, he shows a stereotyped courting behavior consisting of a hyperflexed posture that is also assumed by the receptive female while they face each other. The copulatory position and pattern is similar to that found in other Lycosoidea: the male mounts the female and makes a total of four palpal insertions while alternating sides. However, after each palpal insertion the male dismounts and returns to a frontal position while biting the gift. Copulatory courtship is evidenced by palpal and leg movements. The copulation ends by female initiative and she almost always retains the nuptial gift. No case of pre-copulatory or post-copulatory cannibalism has been recorded. Descriptions of nuptial gift construction by males and copulation in these species, as well as hypotheses about the origin of nuptial gift construction among spiders, are presented. These descriptions are the first records of such nuptial gift offering for Neotropical spiders and for non-Pisauridae species as well.

  20. 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

  1. New additions to the Honduran fauna of spider wasps (Hymenoptera: Pompilidae) with the description of two species.

    PubMed

    Waichert, Cecilia; Rodriguez, Juanita; Pitts, James P

    2014-10-20

    Two new species of pepsine spider wasps, Calopompilus setaerotundus Waichert & Pitts, sp. nov. and Priocnemis (Umbripennis) wasbaueri Waichert & Pitts, sp. nov., are described and illustrated. Calopompilus Ashmead, Priocnemis Schiødte and sixteen additional species are newly reported from Honduras. A new combination is proposed for Ageniella fragilis (Fox), comb. nov., which is transferred from Agenia Schiødte. 

  2. 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

    2012-08-07

    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.

  3. 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.

  4. Tubuliform silk protein: A protein with unique molecular characteristics and mechanical properties in the spider silk fibroin family

    NASA Astrophysics Data System (ADS)

    Tian, M.; Lewis, R. V.

    2006-02-01

    Orb-web weavers can produce up to six different types of silk and a glue for various functions. Tubuliform silk is unique among them due to its distinct amino acid composition, specific time of production, and atypical mechanical properties. To study the protein composing this silk, tubuliform gland cDNA libraries were constructed from three orb-weaving spiders Argiope aurantia, Araneus gemmoides, and Nephila clavipes. Amino acid composition comparison between the predicted tubuliform silk protein sequence (TuSp1) and the corresponding gland protein confirms that TuSp1 is the major component in tubuliform gland in three spiders. Sequence analysis suggests that TuSp1 shares no significant similarity with its paralogues, while it has conserved sequence motifs with the most primitive spider, Euagrus chisoseus silk protein. The presence of large side-chain amino acids in TuSp1 sequence is consistent with the frustrated β-sheet crystalline structure of tubuliform silk observed in transmission electron microscopy. Repeat unit comparison within species as well as among three spiders exhibits high sequence conservation. Parsimony analysis based on carboxy terminal sequence shows that Argiope and Araneus are more closely related than either is to Nephila which is consistent with phylogenetic analysis based on morphological evidence.

  5. 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

  6. New species and distribution records of selenopid spiders of the genus Hovops Benoit in Madagascar (Araneae, Selenopidae).

    PubMed

    Artigas, Sandra Mónica Rodriguez; Corronca, Jose Antonio

    2014-03-24

    Hovops Benoit is a heterogeneous genus of selenopid spiders that was prior to this study represented by seven species that are endemic to Madagascar. Here, we describe four new species: H. antakarana sp. n. (♀), H. ikongo sp. n. (♀), H. menabe sp. n. (♀), and H. vezo sp. n. (♀). A map of the new species is provided as well as new records on two of the known species H. pusillus (Simon, 1897) and H. legrasi (Simon, 1887).

  7. 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.

  8. PCR-RFLP analysis for identification of Tetranychus spider mite species (Acari: Tetranychidae).

    PubMed

    Arimoto, Makoto; Satoh, Masaru; Uesugi, Ryuji; Osakabe, Masahiro

    2013-04-01

    A polymerase chain reaction (PCR)-restriction fragment length polymorphism (PCR-restriction fragment-length polymorphism)-based method for species identification was applied to 14 Tetranychus spider mite species, which were dominant species intercepted at Japanese import plant quarantine. We sequenced the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA (rDNA), which included the partial ends of the 18S and 28S ribosomal RNA genes, 5.8S ribosomal RNA gene, and two internal transcribed spacers (ITS1 and ITS2) for 15 populations of the 14 species. We analyzed the recognition sites of four restriction endonucleases, which had been proposed for discrimination of Japanese Tetranychus species, and constructed a scheme for Tetranychus species identification by PCR-restriction fragment-length polymorphism. We then applied the scheme to 245 individuals from 199 populations, most of them were from foreign countries. As a result, all 14 species were correctly identified using PCR-restriction fragment-length polymorphism. This demonstrates the usefulness of the PCR-restriction fragment-length polymorphism method for the worldwide identification of Tetranychus species.

  9. 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.

  10. 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.

  11. New species of Habronattus and Pellenes jumping spiders (Araneae, Salticidae, Harmochirina)

    PubMed Central

    Maddison, Wayne P.

    2017-01-01

    Abstract The harmochirine jumping spiders include the New World Habronattus, notable for their complex courtship displays, and Pellenes, found throughout the Old World and North America. Five new species of Habronattus and one new species of Pellenes are here described from North America: Habronattus aestus, sp. n., Habronattus chamela sp. n., Habronattus empyrus sp. n., Habronattus luminosus sp. n., Habronattus roberti sp. n., and Pellenes canadensis sp. n. For each of the new species, photographs of living specimens are given, as well as notes on habitat. The new subgenus Pellenattus is described for the subgroup of Pellenes restricted to North America, with type species Pellenes peninsularis Emerton, 1925. Species placed in Pellenes (Pellenattus) are Pellenes apacheus Lowrie & Gertsch, 1955, Pellenes canadensis sp. n., Pellenes crandalli Lowrie & Gertsch, 1955, Pellenes dorsalis (Banks, 1898b), Pellenes grammaticus Chamberlin 1925, Pellenes levii Lowrie & Gertsch, 1955, Pellenes limatus Peckham & Peckham, 1901, Pellenes longimanus Emerton, 1913, Pellenes peninsularis Emerton, 1925, Pellenes shoshonensis Gertsch, 1934, and Pellenes washonus Lowrie & Gertsch, 1955. Pellenes wrighti Lowrie & Gertsch, 1955 is synonymized with Pellenes peninsularis. Attention is drawn to an undescribed species of Habronattus from Canada whose only known specimen is apparently lost. PMID:28228675

  12. 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

  13. A comparison of populations of island and adjacent mainland species of Caribbean Selenops (Araneae: Selenopidae) spiders.

    PubMed

    Crews, Sarah C; Puente-Rolón, Alberto R; Rutstein, Elliot; Gillespie, Rosemary G

    2010-03-01

    The role of the landscape in structuring populations has been the focus of numerous studies, in particular, the extent to which islands provide opportunities for isolation, and the consistency of such an effect across lineages. The current study examines this phenomenon using a series of relatively widespread taxa, all within a single genus of spiders, Selenops. We focus on the Caribbean Islands and adjacent Mesoamerican mainland to examine how the islands per se dictate structure across lineages. We use molecular genetic data from mitochondrial and nuclear genes to examine the population structure of seven species of Selenops. Comparisons are made between species found in the Greater Antilles, Lesser Antilles, and adjacent mainland. Results indicate that geography has little effect on the population structure of mainland species. In contrast, population structure appears to be partitioned by island in the insular Caribbean. Within islands, the amount of population structure for each species is variable and may be dictated more by ecological or demographic parameters, rather than geographic location. The overall conclusion is that the extent to which a given lineage is structured is highly variable across species, with this variability overwhelming any general signal of geographical isolation.

  14. 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.

  15. 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.

  16. 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

    2016-04-07

    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.

  17. 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. 

  18. Giant wood spider Nephila pilipes alters silk protein in response to prey variation.

    PubMed

    Tso, I-Min; Wu, Hsuan-Chen; Hwang, In-Ru

    2005-03-01

    Recent studies have demonstrated that orb-weaving spiders may alter web structures, foraging localities or silk output in response to prey variations. In this study we conducted field surveys and food manipulations to examine whether orb-weaving spiders may also adjust the protein of silk to prey variations. A comparison of dragline silks collected from nine giant wood spider Nephila pilipes populations in Taiwan showed a spatial variation. The percentage of all amino acids (except alanine and glycine) exhibited significant differences among populations. A survey of prey composition also revealed a significant spatial variation among N. pilipes populations. To determine whether prey variation was responsible for silk protein variation, we fed N. pilipes with different types of prey (dipteran vs orthopteran) then compared the percentage of five major dragline amino acids and secondary structures. The results showed that dragline of N. pilipes fed with orthopteran prey contained significantly higher proline and glutamine but lower alanine. Congruent with this result were those from FTIR spectroscopy, which showed that dragline of N. pilipes fed with crickets exhibited significantly higher percentage of proline- and glutamine-containing beta turns, and lower percentage of alanine-containing beta sheet structures. Since the results of feeding manipulations showed that diet significantly affected the compositions of dragline silks, the observed spatial variation seemed to reflect the different types of prey these spiders had consumed. Results of this study thus indicated that orb-weaving spiders can alter dragline protein in response to prey variations.

  19. 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.

  20. On three endemic species of the linyphiid spider genus Canariphantes Wunderlich, 1992 (Araneae, Linyphiidae) from the Azores archipelago.

    PubMed

    Crespo, Luís Carlos; Bosmans, Robert; Cardoso, Pedro; Borges, Paulo A V

    2014-07-28

    We describe Canariphantes junipericola n. sp. and C. relictus n. sp., new single-island endemic linyphiid spiders from the islands of Flores and Santa Maria (Azorean archipelago, Macaronesia), respectively. The female of the first species was incorrectly assigned to Canariphantes acoreensis (Wunderlich, 1992), a species occurring in four islands in the Central Group of Azores (Faial, Pico, São Jorge and Terceira). The latter species is transferred to Canariphantes, its male redescribed and the female genitalia described for the first time. We discuss the systematic affinities of these new species and comment on their conservation status. 

  1. Analysis of major ampullate silk cDNAs from two non-orb-weaving spiders.

    PubMed

    Tian, Maozhen; Liu, Congzhou; Lewis, Randolph

    2004-01-01

    Compared to other arthropods, spiders are unique in their use of silk throughout their life span and the extraordinary mechanical properties of the silk threads they produce. Studies on orb-weaving spider silk proteins have shown that silk proteins are composed of highly repetitive regions, characterized by alanine and glycine-rich units. We have isolated and sequenced four partial cDNA clones representing major ampullate spider silk gene transcripts from two non-orb weavers: three for Kukulcania hibernalis and one for Agelenopsis aperta. These cDNA sequences were compared to each other, as well as to the previously published orb-weaver silk gene sequences. The results indicate that the repeats encoding conserved amino acid motifs such as polyA and polyGA that are characteristic of some orb-weaving spider silks are also found in some of the cDNAs reported in this study. However, we also found other motifs such as polyGS and polyGV in the cDNA sequences from the two non-orb-weaving spiders. The amino acid composition of the silk gland extracts shows that alanine and glycine are the major components of the silk of these two non-orb weavers as is the case in orb-weaver silks. Sequence alignment shows that A. aperta's cDNA displays a C-terminal encoding region that is about 44% similar to the one present in N. clavipes's MaSp1 cDNA. In addition, as previously observed for spider silk sequences, the analysis of the codon usage for these four cDNAs demonstrates a bias for A or T in the wobble base position.

  2. 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.

  3. 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.

  4. A physicochemical characterization of fully acetylated chitin structure isolated from two spider species: with new surface morphology.

    PubMed

    Kaya, Murat; Seyyar, Osman; Baran, Talat; Erdoğan, Sevil; Kar, Musa

    2014-04-01

    Spiders are a huge group which includes more than 44,000 species. But there has been no study of the chitin structure of spiders. In this study we physicochemically characterized chitin structure of two common spider species (Geolycosa vultuosa and Hogna radiata). Chitin content was determined as 8-8.5% for G. vultuosa and 6.5-7% for H. radiata. FTIR, TGA and XRD results showed that the chitin structures are in α-form. Environmental scanning electron microscopy (ESEM) revealed that the surface morphology of each species is different. Chitin yielded from G. vultuosa has two different pore structures. The type one pore is rarely sequenced and its size ranges between 190 and 240 nm, while the type two pore is tightly sequenced and its size ranges between 11 and 32 nm. There is no information in previous studies about the chitin structure with two different pore morphologies. A new chitin surface morphology has been determined in G. vultuosa. The chitin isolated from H. radiata, has classic morphology: nanofibre structures (10-17 nm) and 195-260 nm sized pores. Acetylation degree of the chitin samples was calculated as 97% for G. vultuosa and 99% for H. radiata in accordance with elemental analysis results.

  5. 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.

  6. Medical aspects of spider bites.

    PubMed

    Vetter, Richard S; Isbister, Geoffrey K

    2008-01-01

    Spiders have been incriminated as causes of human suffering for centuries, but few species worldwide cause medically significant envenomation. Widow spiders (Latrodectus spp.) occur worldwide and cause latrodectism, which is characterized by pain (local and generalized) associated with nonspecific systemic effects, diaphoresis, and less commonly other autonomic and neurological effects. Recluse spiders (Loxosceles spp.) are distributed mostly through the tropical and subtropical Western Hemisphere and can cause severe skin lesions and rarely systemic effects; most bites are unremarkable. Highly dangerous spiders in South America (armed spiders) and Australia (funnel-web spiders) cause rare but severe envenomation requiring medical intervention and sometimes antivenom. Most other spiders involved in verified bites cause minor, transient effects. Many spiders blamed for causing medical mischief have been elevated to medical significance via circumstantial evidence, poor reporting, and repetitive citation in the literature; several species have been shown to be harmless with more stringent scientific evidence involving verified bites in humans.

  7. 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

    2012-05-07

    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.

  8. 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.

  9. 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.

  10. 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

  11. Four new species of the trapdoor spider genus Conothele Thorell, 1878 from Mainland China and Laos (Araneae, Ctenizidae)

    PubMed Central

    Xu, Xin; Xu, Chen; Liu, Fengxiang; Zhang, Zengtao; Li, Daiqin

    2017-01-01

    Abstract Here for the first time the presence of the trapdoor spider genus Conothele Thorell, 1878 (Araneae: Ctenizidae) is reported from mainland China and Laos. Four Conothele species collected from the regions are described as new to science, based on the female genital morphology: Conothele baiyunensis Xu, Xu & Liu, sp. n. (Guangdong Province), Conothele daxinensis Xu, Xu & Li, sp. n. (Guangxi Province), Conothele sidiechongensis Xu, Xu & Liu, sp. n. (Yunnan Province, China and Vietnam), Conothele yundingensis Xu, Xu & Li, sp. n. (Yunnan Province). PMID:28144176

  12. 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.

  13. Web-building spiders attract prey by storing decaying matter

    NASA Astrophysics Data System (ADS)

    Bjorkman-Chiswell, Bojun T.; Kulinski, Melissa M.; Muscat, Robert L.; Nguyen, Kim A.; Norton, Briony A.; Symonds, Matthew R. E.; Westhorpe, Gina E.; Elgar, Mark A.

    The orb-weaving spider Nephila edulis incorporates into its web a band of decaying animal and plant matter. While earlier studies demonstrate that larger spiders utilise these debris bands as caches of food, the presence of plant matter suggests additional functions. When organic and plastic items were placed in the webs of N. edulis, some of the former but none of the latter were incorporated into the debris band. Using an Y-maze olfactometer, we show that sheep blowflies Lucilia cuprina are attracted to recently collected debris bands, but that this attraction does not persist over time. These data reveal an entirely novel foraging strategy, in which a sit-and-wait predator attracts insect prey by utilising the odours of decaying organic material. The spider's habit of replenishing the debris band may be necessary to maintain its efficacy for attracting 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. 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.

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

    NASA Astrophysics Data System (ADS)

    Herzig, Volker; Ikonomopoulou, Maria; Smith, Jennifer J.; Dziemborowicz, Sławomir; Gilchrist, John; Kuhn-Nentwig, Lucia; Rezende, Fernanda Oliveira; Moreira, Luciano Andrade; Nicholson, Graham M.; Bosmans, Frank; King, Glenn F.

    2016-07-01

    The inexorable decline in the armament of registered chemical insecticides has stimulated research into environmentally-friendly alternatives. Insecticidal spider-venom peptides are promising candidates for bioinsecticide development but it is challenging to find peptides that are specific for targeted pests. In the present study, we isolated an insecticidal peptide (Ae1a) from venom of the African spider Augacephalus ezendami (family Theraphosidae). Injection of Ae1a into sheep blowflies (Lucilia cuprina) induced rapid but reversible paralysis. In striking contrast, Ae1a was lethal to closely related fruit flies (Drosophila melanogaster) but induced no adverse effects in the recalcitrant lepidopteran pest Helicoverpa armigera. Electrophysiological experiments revealed that Ae1a potently inhibits the voltage-gated sodium channel BgNaV1 from the German cockroach Blattella germanica by shifting the threshold for channel activation to more depolarized potentials. In contrast, Ae1a failed to significantly affect sodium currents in dorsal unpaired median neurons from the American cockroach Periplaneta americana. We show that Ae1a interacts with the domain II voltage sensor and that sensitivity to the toxin is conferred by natural sequence variations in the S1–S2 loop of domain II. The phyletic specificity of Ae1a provides crucial information for development of sodium channel insecticides that target key insect pests without harming beneficial species.

  17. 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.

  18. 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

    2016-07-07

    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.

  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. 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

  1. Tarantula spider

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002855.htm Tarantula spider bite To use the sharing features on this ... This article describes the effects of a tarantula spider bite. This article is for information only. DO ...

  2. Phylogeography of a good Caribbean disperser: Argiope argentata (Araneae, Araneidae) and a new ‘cryptic’ species from Cuba

    PubMed Central

    Agnarsson, Ingi; LeQuier, Stephanie M.; Kuntner, Matjaž; Cheng, Ren-Chung; Coddington, Jonathan A.; Binford, Greta

    2016-01-01

    Abstract The Caribbean islands harbor rich biodiversity with high levels of single island endemism. Stretches of ocean between islands represent significant barriers to gene-flow. Yet some native species are widespread, indicating dispersal across oceans, even in wingless organisms like spiders. Argiope argentata (Fabricius, 1775) is a large, charismatic, and widespread species of orb-weaving spider ranging from the United States to Argentina and is well known to balloon. Here we explore the phylogeography of Argiope argentata in the Caribbean as a part of the multi-lineage CarBio project, through mtDNA haplotype and multi-locus phylogenetic analyses. The history of the Argiope argentata lineage in the Caribbean goes back 3-5 million years and is characterized by multiple dispersal events and isolation-by-distance. We find a highly genetically distinct lineage on Cuba which we describe as Argiope butchko sp. n. While the argentata lineage seems to readily balloon shorter distances, stretches of ocean still act as filters for among-island gene-flow as evidenced by distinct haplotypes on the more isolated islands, high FST values, and strong correlation between intraspecific (but not interspecific) genetic and geographic distances. The new species described here is clearly genetically diagnosable, but morphologically cryptic, at least with reference to the genitalia that typically diagnose spider species. Our results are consistent with the intermediate dispersal model suggesting that good dispersers, such as our study species, limit the effect of oceanic barriers and thus diversification and endemism. PMID:27833425

  3. Molecular phylogenetics at the population/species interface in cave spiders of the southern Appalachians (Araneae:Nesticidae:Nesticus).

    PubMed

    Hedin, M C

    1997-03-01

    This paper focuses on the relationship between population genetic structure and speciation mechanisms in a monophyletic species group of Appalachian cave spiders (Nesticus). Using mtDNA sequence data gathered from 256 individuals, I analyzed patterns of genetic variation within and between populations for three pairs of closely related sister species. Each sister-pair comparison involves taxa with differing distributional and ecological attributes; if these ecological attributes are reflected in basic demographic differences, then speciation might proceed differently across these sister taxa comparisons. Both frequency-based and gene tree analyses reveal that the genetic structure of the Nesticus species studied is characterized by similar and essentially complete population subdivision, regardless of differences in general ecology. These findings contrast with results of prior genetic studies of cave-dwelling arthropods that have typically revealed variation in population structure corresponding to differences in general ecology. Species fragmentation through both extrinsic and intrinsic evolutionary forces has resulted in discrete, perhaps independent, populations within morphologically defined species. Large sequence divergence values observed between populations suggest that this independence may extend well into the past. These patterns of mtDNA genealogical structure and divergence imply that species as morphological lineages are currently more inclusive than basal evolutionary or phylogenetic units, a suggestion that has important implications for the study of speciation mechanisms.

  4. Spiders avoid sticking to their webs: clever leg movements, branched drip-tip setae, and anti-adhesive surfaces

    NASA Astrophysics Data System (ADS)

    Briceño, R. D.; Eberhard, W. G.

    2012-04-01

    Orb-weaving spiders construct webs with adhesive silk but are not trapped by it. Previous studies have attributed this defense to an oily coating on their legs that protects against adhesion or, more recently, to behavioral avoidance of sticky lines. The old evidence is very weak, however, and the behavioral avoidance explanation is inadequate because orb-weavers push with their hind legs against sticky lines hundreds or thousands of times during construction of each orb and are not trapped. Video analyses of behavior and experimental observations of isolated legs pulling away from contact with sticky lines showed that the spider uses three anti-adhesion traits: dense arrays of branched setae on the legs that reduce the area of contact with adhesive material; careful engagement and withdrawal movements of its legs that minimize contact with the adhesive and that avoid pulling against the line itself; and a chemical coating or surface layer that reduces adhesion.

  5. On the trapdoor spiders of Mexico: description of the first new species of the spider genus Aptostichus from Mexico and the description of the female of Eucteniza zapatista (Araneae, Mygalomorphae, Euctenizidae).

    PubMed

    Valdez-Mondragón, Alejandro; Cortez-Roldán, Mayra R

    2016-01-01

    A new species of the spider genus Aptostichus Simon, 1891 is described from a cave in Huautla de Jiménez, Oaxaca, Mexico: Aptostichus sabinaesp. n. This species represents the first new species described from Mexico and the southernmost record in North America for the genus so far. Aptostichus sabinaesp. n. represents the forty-first species described for the genus, which has the highest species diversity in the family Euctenizidae. Eucteniza zapatista is redescribed based on five new males and the first known female from the Parque Nacional La Malinche (PNLM), Tlaxcala Mexico. Eucteniza zapatista is the fourth species of the genus where a female is known, and one of fourteen species described for the genus to date.

  6. On the trapdoor spiders of Mexico: description of the first new species of the spider genus Aptostichus from Mexico and the description of the female of Eucteniza zapatista (Araneae, Mygalomorphae, Euctenizidae)

    PubMed Central

    Valdez-Mondragón, Alejandro; Cortez-Roldán, Mayra R.

    2016-01-01

    Abstract A new species of the spider genus Aptostichus Simon, 1891 is described from a cave in Huautla de Jiménez, Oaxaca, Mexico: Aptostichus sabinae sp. n. This species represents the first new species described from Mexico and the southernmost record in North America for the genus so far. Aptostichus sabinae sp. n. represents the forty-first species described for the genus, which has the highest species diversity in the family Euctenizidae. Eucteniza zapatista is redescribed based on five new males and the first known female from the Parque Nacional La Malinche (PNLM), Tlaxcala Mexico. Eucteniza zapatista is the fourth species of the genus where a female is known, and one of fourteen species described for the genus to date. PMID:28138292

  7. 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

  8. 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

  9. 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.

  10. On the poorly known haplogynae spiders of the genus Ochyrocera Simon (Araneae, Ochyroceratidae) from Mexico: description of two new species with an updated identification key for Mexican species.

    PubMed

    Valdez-Mondragón, Alejandro

    2017-01-26

    Two new species of the spider genus Ochyrocera Simon 1891 are described from Mexico. Ochyrocera jarocha new species was collected under rotten trunks and hollow trunks in a tropical rainforest, in San Martin Volcano, Veracruz, Mexico. Ochyrocera pojoj new species was collected in a mixed forest, under rotten trunks, in La Trinitaria, Chiapas, Mexico, which represents the third species described from the state of Chiapas. With the description of the two new species herein, six species of Ochyrocera are recorded from Mexico. An updated taxonomic identification key and a distribution map to the Mexican species are provided.

  11. Spider webs designed for rare but life-saving catches.

    PubMed

    Venner, Samuel; Casas, Jérôme

    2005-08-07

    The impact of rare but positive events on the design of organisms has been largely ignored, probably due to the paucity of recordings of such events and to the difficulty of estimating their impact on lifetime reproductive success. In this respect, we investigated the size of spider webs in relation to rare but large prey catches. First, we collected field data on a short time-scale using the common orb-weaving spider Zygiella x-notata to determine the distribution of the size of prey caught and to quantify the relationship between web size and daily capture success. Second, we explored, with an energetic model, the consequences of an increase in web size on spider fitness. Our results showed that (i) the great majority of prey caught are quite small (body length less than 2mm) while large prey (length greater than 10mm) are rare, (ii) spiders cannot survive or produce eggs without catching these large but rare prey and (iii) increasing web size increases the daily number of prey caught and thus long-term survival and fecundity. Spider webs seem, therefore, designed for making the best of the rare but crucial event of catching large prey.

  12. 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

    2016-04-05

    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.

  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. A spider species complex revealed high cryptic diversity in South China caves.

    PubMed

    Zhang, Yuanyuan; Li, Shuqiang

    2014-10-01

    Cryptic species, which are an important component of biodiversity, have rarely been studied in South China karst. We investigated cryptic diversity in the cave species complex Telema cucurbitina, which has a narrow niche but widespread distribution among multiple caves. We sampled another 15 populations (caves) in addition to the population from the type locality. Phylogenetic results indicated that individuals from the same cave constituted well-supported clades. Species diversity within this species complex was assessed in a coalescent framework, first with a Bayesian extension of the general mixed Yule coalescent (bGMYC) model and a Bayesian species delimitation method (BPP). Both species delimitation methods identified each cave population as a separate species. We propose that each cave population within this species complex was a separate evolving lineage and therefore 16 OTUs were recovered based on our molecular data despite their high morphological similarities. We also propose that the unrecognized organism's diversity within South China caves might be extremely large considering our case. Furthermore, our work reveals that species discovery of cave organisms by morphological data has a high probability of underestimating hidden diversity. Our work also highlights the need for conservation strategies to protect this largely neglected diversity of cave organisms.

  15. 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

  16. Thirteen new species of the spider genus Karaops (Araneae: Selenopidae) from Western Australia.

    PubMed

    Crews, Sarah C

    2013-01-01

    Thirteen new species of the recently-described genus Karaops Crews and Harvey, 2011 are described from Western Australia, bringing the total number of species of this genus to 37. The new species are K. umiida sp. nov. (female, male), K. nyiyaparli sp. nov. (female), K. kariyarra sp. nov. (female), K. yurlburr sp. nov. (female, male), K. feedtime sp. nov. (female), K. forteyi sp. nov. (female, male), K. yindjibarndi sp. nov. (male), K. jaburrara sp. nov. (male), K. ngarluma sp. nov. (male), K. nyangunarta sp. nov. (female, male), K. nyamal sp. nov. (female), K. banyjima sp. nov. (female) and K. yumbu sp. nov. (male). The male of K. inartamarta Crews and Harvey, 2011 is described for the first time, and new distribution records are given for this species and for K. burbidgei Crews and Harvey, 2011. Finally, a new key' to all of the described species of Karaops is provided.

  17. 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.

  18. 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

  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. Swiss prospective study on spider bites.

    PubMed

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

    2013-09-04

    Knowledge of spider bites in Central Europe derives mainly from anecdotal case presentations; therefore we aimed to collect cases systematically. From June 2011 to November 2012 we prospectively collected 17 cases of alleged spider bites, and together with two spontaneous notifications later on, our database totaled 19 cases. Among them, eight cases could be verified. The causative species were: Cheiracanthium punctorium (3), Zoropsis spinimana (2), Amaurobius ferox, Tegenaria atrica and Malthonica ferruginea (1 each). Clinical presentation was generally mild, with the exception of Cheiracanthium punctorium, and patients recovered fully without sequelae. In Switzerland, spider bites generally have a benign clinical course, which is characterised by minor effects, with rapid and complete recovery. Since only verified spider bites can be regarded as spider bites, in the case of clinically important arachnidism, the spider should be sent to an expert for identification. Our study may help to diminish spider fear and reassure people who have experienced a bite.

  1. Counterattack success of a social spider mite against two predominant phytoseiid predator species.

    PubMed

    Saito, Yutaka; Chittenden, Anthony R; Kanazawa, Miki

    2011-11-01

    A survey was conducted of the predator fauna occurring in and around the nests of the two forms (LW: low male aggression and HG: high male aggression) of Stigmaeopsis miscanthi (Saito) that occur in Japan. Two phytoseiid species, Neoseiulus womersleyi (Schicha) and Typhlodromus bambusae Ehara predominated in S. miscanthi nests and their respective occurrence frequencies were the same in LW form nests as in HG form nests. We examined the counterattack success of S. miscanthi LW form males against these two phytoseiid predators. It was shown that while LW form male(s) could kill or effectively drive the larvae of both predator species out of their nests, there were no significant differences in the male counterattack success rate between 1-male and 2-male defended nests, or against the two predator species. On the other hand, there was a significant difference between the two predator species' behavioral response to male-defended nests.

  2. 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.

  3. Bites by Australian mygalomorph spiders (Araneae, Mygalomorphae), including funnel-web spiders (Atracinae) and mouse spiders (Actinopodidae: Missulena spp).

    PubMed

    Isbister, Geoffrey K; Gray, Mike R

    2004-02-01

    A number of mygalomorph spiders cause bites in Australia, including the funnel-web spiders (Hexathelidae, Atracinae: Hadronyche and Atrax) and mouse spiders (Actinopodidae: Missulena). There is ongoing debate about the significance of bites by mouse spiders and the frequency of severe envenoming by funnel-web spiders. We conducted a prospective cohort study of definite spider bites with expert spider identification and include the analysis of mygalomorph spiders here. Subjects were recruited prospectively from February 1999 to April 2003 from patients presenting to participating hospitals or contacting a state poison information centre. Forty-nine cases of bites by mygalomorph spiders were included: 16 were by funnel-web spiders, 13 by mouse spiders and 20 by other trapdoor spiders (Families Idiopidae and Nemesiidae). Of the 49 bites, 45 (92%) occurred on distal limbs (hands and feet). Local effects included severe pain (53%), puncture marks (61%) and bleeding (27%), local redness (33%). Itchiness did not occur. The following were highly statistically associated with mygalomorph spider bites compared to all other spiders (p<0.0001) circumstances (gardening at the time (likelihood ratio (LR) 7.9) and distal limb bites (LR 2.0)) and early clinical features (presence of puncture marks OR bleeding (2.3), or severe pain (2.0)). Of 16 funnel-web spider bites, there were 10 cases with minor local effects, four with moderate envenoming (non-specific systemic or local neurotoxicity) and two with severe envenoming requiring antivenom. In addition to local effects, mouse spider bites caused local paraesthesia in three cases, local diaphoresis in one case and non-specific systemic effects in five cases, but not severe envenoming. True trapdoor spider bites caused only minor effects. The data from a mixed species sample of funnel-web spiders confirms previous observations suggesting that only a small proportion of funnel-web bites cause severe effects. Mouse spider bites are

  4. 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

  5. Two new jumping spider species of the Habronattus clypeatus group (Araneae, Salticidae, Harmochirina)

    PubMed Central

    Maddison, Wayne P.; Maddison, David R.

    2016-01-01

    Abstract Two species of the Habronattus clypeatus species group are described, Habronattus arcalorus sp. n. from Texas and Colorado, and Habronattus gilaensis sp. n. from New Mexico. Habronattus arcalorus males have extravagant ornamentation: a green first leg with an unusually dense lateral fringe of orange and white hairs, and a large grey triangular patella on the third leg with blue-white scales nearby. Habronattus gilaensis males are considerably more muted, lacking ornamentation on the third leg’s patella and tibia. Photographs of living specimens are given, as well as notes on habitat. PMID:27833423

  6. 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

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

    PubMed

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

    2016-03-03

    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.

  8. 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

  9. 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 ...

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Wolf spider bites.

    PubMed

    Campbell, D S; Rees, R S; King, L E

    1987-02-01

    Because of their dark color and hunting habits, wolf spiders (Lycosidae) are often confused with the much more dangerous brown recluse spider (Loxosceles reclusa). Unlike the brown recluse spider, wolf spider envenomation seldom causes cutaneous necrosis or systemic symptoms. In this report, two documented cases of wolf spider bites are described and the pertinent literature reviewed.

  16. Spiders do have melanin after all.

    PubMed

    Hsiung, Bor-Kai; Blackledge, Todd A; Shawkey, Matthew D

    2015-11-01

    Melanin pigments are broadly distributed in nature - from bacteria to fungi to plants and animals. However, many previous attempts to identify melanins in spiders were unsuccessful, suggesting that these otherwise ubiquitous pigments were lost during spider evolution. Yet, spiders exhibit many dark colours similar to those produced by melanins in other organisms, and the low solubility of melanins makes isolation and characterization difficult. Therefore, whether melanins are truly absent or have simply not yet been detected is an open question. Raman spectroscopy provides a reliable way to detect melanins in situ, without the need for isolation. In this study, we document the presence of eumelanin in diverse species of spiders using confocal Raman microspectroscopy. Comparisons of spectra with theoretically calculated data falsify the previous hypothesis that dark colours are produced solely by ommochromes in spiders. Our data indicate that melanins are present in spiders and further supporting that they are present in most living organisms.

  17. Visual expertise does not predict the composite effect across species: A comparison between spider (Ateles geoffroyi) and rhesus (Macaca mulatta) monkeys

    PubMed Central

    Taubert, Jessica; Parr, Lisa A.

    2009-01-01

    Humans are subject to the composite illusion: two identical top halves of a face are perceived as “different” when they are presented with different bottom halves. This observation suggests that when building a mental representation of a face, the underlying system perceives the whole face, and has difficulty decomposing facial features. We adapted a behavioural task that measures the composite illusion to examine the perception of faces in two nonhuman species. Specifically we had spider (Ateles geoffroyi) and rhesus monkeys (Macaca mulatta) perform a two-forced choice, match-to-sample task where only the top half of sample was relevant to the task. The results of Experiment 1 show that spider monkeys (N = 2) process the faces of familiar species (conspecifics and humans, but not chimpanzees, sheep, or sticks), holistically. The second experiment tested rhesus monkeys (N = 7) with the faces of humans, chimpanzees, gorillas, sheep and sticks. Contrary to prediction, there was no evidence of a composite effect in the human (or familiar primate) condition. Instead, we present evidence of a composite illusion in the chimpanzee condition (an unfamiliar primate). Together, these experiments show that visual expertise does not predict the composite effect across the primate order. PMID:19815323

  18. 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

  19. 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.

  20. Spider Vein Removal

    MedlinePlus

    Spider veins: How are they removed? I have spider veins on my legs. What options are available ... M.D. Several options are available to remove spider veins — thin red lines or weblike networks of ...

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Gregorič, Matjaž; Kiesbüy, Heine C.; Quiñones Lebrón, Shakira G.; 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.

  3. 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.

  4. Ultrastructural and molecular identification of a Wolbachia endosymbiont in a spider, Nephila clavata.

    PubMed

    Oh, H W; Kim, M G; Shin, S W; Bae, K S; Ahn, Y J; Park, H Y

    2000-10-01

    Wolbachia-like bacteria were observed in the egg cells of golden orb-weaving spider, Nephila clavata, by means of transmission electron microscopy. The bacteria exhibited the typical morphology of Wolbachia, including three enveloping membranes. Based on the amplification and sequencing of partial 16S rDNA and ftsZ gene, the bacteria were identified as Wolbachia, intracellular, transovarially inherited alpha-proteobacteria in invertebrates. Phylogenetic analysis based on 16S rDNA and ftsZ gene sequences invariably indicated that the intracellular bacteria from N. clavata belonged to group A Wolbachia, which were found only from insects. Clustering of Wolbachia from N. clavata with group A Wolbachia indicates that the bacteria were probably transferred horizontally between insects and the spider.

  5. 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

  6. 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.

  7. Investigating the transverse optical structure of spider silk micro-fibers using quantitative optical microscopy

    NASA Astrophysics Data System (ADS)

    Little, Douglas J.; Kane, Deb M.

    2016-10-01

    The transverse optical structure of two orb-weaver (family Araneidae) spider dragline silks was investigated using a variant of the inverse-scattering technique. Immersing the silks in a closely refractive index-matched liquid, the minimum achievable image contrast was greater than expected for an optically homogeneous silk, given what is currently known about the optical absorption of these silks. This "excess contrast" indicated the presence of transverse optical structure within the spider silk. Applying electromagnetic scattering theory to a transparent double cylinder, the minimum achievable irradiance contrast for the Plebs eburnus and Argiope keyserlingi dragline silks was determined to be consistent with step index refractive index contrasts of 1-4×10-4 and 6-7×10-4, respectively, supposing outer-layer thicknesses consistent with previous TEM studies (50 nm and 100 nm, respectively). The possibility of graded index refractive index contrasts within the spider silks is also discussed. This is the strongest evidence, to date, that there is a refractive index contrast associated with the layered morphology of spider silks and/or variation of proportion of nanocrystalline components within the spider silk structure. The method is more generally applicable to optical micro-fibers, including those with refractive index variations on a sub-wavelength scale.

  8. Investigating the transverse optical structure of spider silk micro-fibers using quantitative optical microscopy

    NASA Astrophysics Data System (ADS)

    Little, Douglas J.; Kane, Deb M.

    2017-01-01

    The transverse optical structure of two orb-weaver (family Araneidae) spider dragline silks was investigated using a variant of the inverse-scattering technique. Immersing the silks in a closely refractive index-matched liquid, the minimum achievable image contrast was greater than expected for an optically homogeneous silk, given what is currently known about the optical absorption of these silks. This "excess contrast" indicated the presence of transverse optical structure within the spider silk. Applying electromagnetic scattering theory to a transparent double cylinder, the minimum achievable irradiance contrast for the Plebs eburnus and Argiope keyserlingi dragline silks was determined to be consistent with step index refractive index contrasts of 1-4×10-4 and 6-7×10-4, respectively, supposing outer-layer thicknesses consistent with previous TEM studies (50 nm and 100 nm, respectively). The possibility of graded index refractive index contrasts within the spider silks is also discussed. This is the strongest evidence, to date, that there is a refractive index contrast associated with the layered morphology of spider silks and/or variation of proportion of nanocrystalline components within the spider silk structure. The method is more generally applicable to optical micro-fibers, including those with refractive index variations on a sub-wavelength scale.

  9. 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)

  10. 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.

  11. 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.

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

    PubMed Central

    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

  13. 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.

  14. 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

  15. Poisonous Spiders: Bites, Symptoms, and Treatment; an Educational Review

    PubMed Central

    Rahmani, Farzad; Banan Khojasteh, Seyed Mahdi; Ebrahimi Bakhtavar, Hanieh; Rahmani, Farnaz; Shahsavari Nia, Kavous; Faridaalaee, Gholamreza

    2014-01-01

    More than 40,000 species of spiders have been identified in the world. Spider bites is a common problem among people, however few of them are harmful but delay in treatment can cause death. Since the spider bites are risk full to human, they should be taken seriously, especially in endemic areas. Our objective in this review was to study about poisonous spiders and find out treatments of them. Therefore, we collected related articles from PubMed database and Google Scholar. Three important syndromes caused by spider bites are loxoscelism, latrodectism and funnel web spider syndrome. Many treatments are used but much more studies should have done to decrease the mortality. In this review, we describes different venomous spiders according to their appearance, symptoms after their bites and available treatments. PMID:26495347

  16. THE EXECUTION OF PLANNED DETOURS BY SPIDER-EATING PREDATORS

    PubMed Central

    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

  17. 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.

  18. 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.

  19. The spider genus Cyrioctea Simon on Chañaral Island (Pingüino de Humboldt National Reserve, Atacama, Chile): description of a new species, and the male of Cyrioctea cruz Platnick (Araneae, Zodariidae).

    PubMed

    Grismado, Cristian J; Pizarro-Araya, Jaime

    2016-05-02

    A faunistic survey on Chañaral Island, Atacama, near the northern Pacific coast of Chile, allowed the discovery and description of a new species of the spider genus Cyrioctea: C. islachanaral sp. nov., based on females collected by pitfall traps. Strikingly, this new species shares morphological characters with some Southern African representatives of this genus rather than with the species of continental South America. The male of the species C. cruz Platnick, previously known from continental Chile (northern Coquimbo), is described for the first time based on specimens collected in the same locality.

  20. 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.

  1. 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.

  2. One-shot genitalia are not an evolutionary dead end - Regained male polygamy in a sperm limited spider species

    PubMed Central

    2011-01-01

    Background Monogynous mating systems with extremely low male mating rates have several independent evolutionary origins and are associated with drastic adaptations involving self-sacrifice, one-shot genitalia, genital damage, and termination of spermatogenesis immediately after maturation. The combination of such extreme traits likely restricts evolutionary potential perhaps up to the point of making low male mating rates irreversible and hence may constitute an evolutionary dead end. Here, we explore the case of a reversion to multiple mating from monogynous ancestry in golden orb-web spiders, Nephila senegalensis. Results Male multiple mating is regained by the loss of genital damage and sexual cannibalism but spermatogenesis is terminated with maturation, restricting males to a single loading of their secondary mating organs and a fixed supply of sperm. However, males re-use their mating organs and by experimentally mating males to many females, we show that the sperm supply is divided between copulations without reloading the pedipalps. Conclusion By portioning their precious sperm supply, males achieve an average mating rate of four females which effectively doubles the maximal mating rate of their ancestors. A heritage of one-shot genitalia does not completely restrict the potential to increase mating rates in Nephila although an upper limit is defined by the available sperm load. Future studies should now investigate how males use this potential in the field and identify selection pressures responsible for a reversal from monogynous to polygynous mating strategies. PMID:21740561

  3. 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.

  4. 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

    2012-04-07

    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.

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

    PubMed Central

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

    2012-01-01

    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

  6. Black widow spider

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/002858.htm Black widow spider To use the sharing features on this page, please enable JavaScript. The black widow spider has a shiny black body with a red ...

  7. Spider Bites (For Parents)

    MedlinePlus

    ... body rash fever and chills fatigue Of a black widow spider bite: rigid, painful muscles within 8 hours no ... child was bitten by a brown recluse or black widow spider Think Prevention! Make sure garages, attics, and woodpiles ...

  8. 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)

  9. 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 ...

  10. 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.

  11. A review of Solenysa spiders from Japan (Araneae, Linyphiidae), with a comment on the type species S. mellotteei Simon, 1894

    PubMed Central

    Wang, Fang; Ono, Hirotsugu; Tu, Lihong

    2015-01-01

    Abstract The present paper gives a review of Solenysa species from Japan and provides a solution for the species bearing the generotype name Solenysa mellotteei Simon, 1894. A total of six species are recorded, including two new species Solenysa macrodonta sp. n. and Solenysa trunciformis sp. n. The species collected from Kawasaki (NSMT-Ar 11154) and Hachioji should be the generotype Solenysa mellotteei, with Solenysa akihisai Tu, 2011, syn. n. as its junior synonym. To distinguish these congeneric species from each other, their genital characters are provided in detail based on images collected by scanning electron microscopy and light microscopy. PMID:25685031

  12. 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.

  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. Spider Bites: First Aid

    MedlinePlus

    ... t had one in the last five years. Black widow spider You can usually identify a black widow spider by the hourglass marking on its belly. The ... in the south. Signs and symptoms of a black widow spider bite may include: At first, slight swelling and ...

  15. 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…

  16. Description of the first cave dwelling species of the spider genus Trilacuna Tong & Li from Iran (Araneae: Oonopidae).

    PubMed

    Hosseini, Mohammad-Javad Malek; Grismado, Cristian J; Sadeghi, Saber; Bakhshi, Yaser

    2015-06-13

    A new species of the hard-bodied oonopid genus Trilacuna Tong & Li is described from a cave in Kohgiluyeh and Boyer-Ahmad Province, southwestern Iran. Trilacuna qarzi sp. nov. is the first troglobiont species known of the genus, and is also the fifth oonopid species to be reported from Iran. Relationships of this new species are briefly discussed in the context of the limits of the genera belonging to the Dysderoides complex.

  17. On the taxonomy of southern South American species of the wolf spider genus Allocosa (Araneae: Lycosidae: Allocosinae).

    PubMed

    Simó, Miguel; Lise, Arno A; Pompozzi, Gabriel; Laborda, Álvaro

    2017-01-06

    Three species of the genus Allocosa Banks, 1900 from southern South America are redescribed: Allocosa alticeps (Mello-Leitão, 1944), A. brasiliensis (Petrunkevitch, 1910) and A. senex (Mello-Leitão, 1945). The female of A. senex is described for the first time and the species is revalidated. A new species, A. marindia sp. nov. from southern Uruguay and southern Brazil is described. The new species is distinguished by the flattened terminal apophysis of the male bulb and the conspicuous pointed projections on the posterior margin of the female epigynum. The species inhabits in sandy estuarine and oceanic coasts with psammophile vegetation.

  18. Spiders (Araneae) Found in Bananas and Other International Cargo Submitted to North American Arachnologists for Identification.

    PubMed

    Vetter, Richard S; Crawford, Rodney L; Buckle, Donald J

    2014-11-01

    Spiders found in international cargo brought into North America are sometimes submitted to arachnologists for identification. Often, these spiders are presumed to be of medical importance because of size or a submitter's familiarity with a toxic spider genus from the continent of origin. Starting in 2006, requests were made for spiders found in international cargo brought into North America, in addition to the specimens from similar cargo shipments already in our museum collections. This was an ad hoc study that allowed us to focus on spiders of concern to the discoverer. We identified 135 spiders found in international cargo. A key for the most common species is provided. The most frequently submitted spiders were the pantropical huntsman spider, Heteropoda venatoria (L.) (Sparassidae), and the redfaced banana spider, Cupiennius chiapanensis Medina Soriano (Ctenidae). Spiders of medical importance were rare. The most common cargo from which spiders were submitted was bananas with most specimens coming from Central America, Ecuador, or Colombia. Lack of experience with nonnative fauna caused several experienced American arachnologists to misidentify harmless ctenid spiders (C. chiapanensis, spotlegged banana spider, Cupiennius getazi Simon) as highly toxic Phoneutria spiders. These misidentifications could have led to costly, unwarranted prophylactic eradication measures, unnecessary employee health education, heightened employee anxiety and spoilage when perishable goods are left unloaded due to safety concerns.

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

    PubMed

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

    2011-04-06

    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.

  20. 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

  1. 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.

  2. 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

  3. 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

  4. New species and phylogenetic relationships of the spider genus Coptoprepes using morphological and sequence data (Araneae: Anyphaenidae).

    PubMed

    Barone, Mariana L; Werenkraut, Victoria; Ramírez, Martín J

    2016-10-17

    We present evidence from the standard cytochrome c oxidase subunit I (COI) barcoding marker and from new collections, showing that the males and females of C. ecotono Werenkraut & Ramírez were mismatched, and describe the female of that species for the first time. An undescribed male from Chile is assigned to the new species Coptoprepes laudani, together with the female that was previously thought as C. ecotono. The matching of sexes is justified after a dual cladistics analysis of morphological and sequence data in combination. New locality data and barcoding sequences are provided for other species of Coptoprepes, all endemic of the temperate forests of Chile and adjacent Argentina. Although morphology and sequences are not conclusive on the relationships of Coptoprepes species, the sequence data suggests that the species without a retrolateral tibial apophysis may belong to an independent lineage.

  5. 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.

  6. 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.

  7. 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.

  8. 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 ...

  9. Secondary Structure Adopted by the Gly-Gly-X Repetitive Regions of Dragline Spider Silk

    PubMed Central

    Gray, Geoffrey M.; van der Vaart, Arjan; Guo, Chengchen; Jones, Justin; Onofrei, David; Cherry, Brian R.; Lewis, Randolph V.; Yarger, Jeffery L.; Holland, Gregory P.

    2016-01-01

    Solid-state NMR and molecular dynamics (MD) simulations are presented to help elucidate the molecular secondary structure of poly(Gly-Gly-X), which is one of the most common structural repetitive motifs found in orb-weaving dragline spider silk proteins. The combination of NMR and computational experiments provides insight into the molecular secondary structure of poly(Gly-Gly-X) segments and provides further support that these regions are disordered and primarily non-β-sheet. Furthermore, the combination of NMR and MD simulations illustrate the possibility for several secondary structural elements in the poly(Gly-Gly-X) regions of dragline silks, including β-turns, 310-helicies, and coil structures with a negligible population of α-helix observed. PMID:27918448

  10. On the identity of the Palearctic species of the wolf spider genus Trebacosa (Araneae: Lycosidae).

    PubMed

    Szűts, Tamás; Zalai, Béla; Villepoux, Olivier; Buchholz, Sascha; Eichardt, János; Zhukovets, Evgeni; Oger, Pierre; Szinetár, Csaba

    2017-01-09

    In this paper we propose Trebacosa brunhesi Villepoux, 2007 as a junior synonym of Trebacosa europaea Szinetár & Kan-csal, 2007 based on the examination of specimens from all the localities from where those species are known. Illustration of the type species of the genus, Trebacosa marxi (Stone, 1890) and specimens from all known localities of T. europaea are given to show both the inter- and the intraspecific differences of the genus. Scanning electron micrographs were used to illustrate the detailed structure of the female's genitalia.

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

    PubMed

    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.

  12. 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

  13. Highly virulent Beauveria bassiana strains against the two-spotted spider mite, Tetranychus urticae, show no pathogenicity against five phytoseiid mite species.

    PubMed

    Wu, Shengyong; Xie, Haicui; Li, Maoye; Xu, Xuenong; Lei, Zhongren

    2016-12-01

    Entomopathogenic fungi and predatory mites can independently contribute to suppressing the two-spotted spider mite, Tetranychus urticae Koch. It is important to assess the risk of possible fungal infections in predators when a combination of them are being considered as a tandem control strategy for suppressing T. urticae. The first part of this study tested 12 Beauveria bassiana isolates for virulence in T. urticae. Strains SCWJ-2, SDDZ-9, LNSZ-26, GZGY-1-3 and WLMQ-32 were found to be the most potent, causing 37.6-49.5% adult corrected mortality at a concentration of 1 × 10(7) m/L conidia 4 days post-treatment. The second part evaluated the pathogenicity of these five strains in five species of predatory phytoseiid mites. The bioassay results indicated that all adult predatory mite mortalities ranged from 7.5 to 9.1% 4 days post-treatment. No viable fungal hyphae were found on predator cadavers. Observations with scanning electron microscopy revealed that conidia were attached to the cuticle of predatory mites within 2-12 h after spraying with strain LNSZ-26, and had germinated within 24-36 h. After 48 h, conidia had gradually been shed from the mites, after none of the conidia had penetrated the cuticular surfaces. In contrast, the germinated conidia successfully penetrated the cuticle of T. urticae, and within 60 h the fungus colonized the mite's body. Our study demonstrated that although several B. bassiana strains displayed a high virulence in T. urticae there was no evident pathogenicity to phytoseiid mites. These findings support the potential use of entomopathogenic fungus in combination with predatory mites in T. urticae control programs.

  14. Seven new species of Psechrus and additional taxonomic contributions to the knowledge of the spider family Psechridae (Araneae).

    PubMed

    Bayer, Steffen

    2014-01-27

    Seven new Psechrus species are described from South East Asia: P. arietinus sp. nov.(♂♀, Vietnam), P. insulanus sp. nov.(♂, Thailand), P. ampullaceus sp. nov.(♂♀, Vietnam), P. omistes sp. nov.(♂, Indonesia, Sumatra), P. quasillus sp. nov.(♂♀, Malaysia, Borneo), P. huberi sp. nov.(♀, Philippines), and P. wade sp. nov.(♂, Philippines). For the following species, new records are listed and intraspecific variation is discussed and illustrated: P. libelti Kulczyński, 1908, P. norops Bayer, 2012, P. rani Wang & Yin, 2001, P. khammouan Jäger, 2007, P. luangprabang Jäger, 2007, P. jaegeri Bayer, 2012, P. obtectus Bayer, 2012, P. kenting Yoshida, 2009 and P. crepido Bayer, 2012, and Fecenia protensa Thorell, 1891. The latter species is recorded from Vietnam for the first time. P. norops, P. libelti and an unidentified Psechrus species from Baluno, Mindanao are for the first time characterised and illustrated by their pre-epigynes and pre-vulvae.

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

    PubMed

    Zaera, Ramón; Soler, Alejandro; Teus, Jaime

    2014-09-06

    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.

  16. 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

  17. 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.

  18. '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.

  19. Brown recluse spider envenomation.

    PubMed

    Furbee, R Brent; Kao, Louise W; Ibrahim, Danyal

    2006-03-01

    Brown recluse spider bite is a common diagnosis in almost every state in America. In fact, cases have been reported in areas where the spider has never been seen. A review of medical literature reveals that most current concepts regarding brown recluse spider envenomation are based on supposition. In this article, we attempt to review critically our present understanding of brown recluse bites with a focus on the published evidence.

  20. Three new species and the first known males of the Andean spider genus Orinomana Strand (Araneae, Uloboridae).

    PubMed

    Grismado, Cristian J; Rubio, Gonzalo D

    2015-12-02

    Three new species of the uloborid genus Orinomana Strand, O. penelope n. sp. from Ecuador, O. viracocha n. sp. from Peru, and O. florezi n. sp. from Colombia, are described. Additionally, the male of O. ascha Grismado, from Northwestern Argentina, is described for the first time. This material includes the first males known of the genus, providing diagnostic characters for its recognition; the complex and massive embolus with several branches is proposed as a synapomorphy of the genus.

  1. Male courtship vibrations delay predatory behaviour in female spiders.

    PubMed

    Wignall, Anne E; Herberstein, Marie E

    2013-12-19

    During courtship, individuals transfer information about identity, mating status and quality. However, male web-building spiders face a significant problem: how to begin courting female spiders without being mistaken for prey? Male Argiope spiders generate distinctive courtship vibrations (shudders) when entering a female's web. We tested whether courtship shudders delay female predatory behaviour, even when live prey is present in the web. We presented a live cricket to females during playbacks of shudder vibrations, or white noise, and compared female responses to a control in which we presented a live cricket with no playback vibrations. Females were much slower to respond to crickets during playback of shudder vibrations. Shudder vibrations also delayed female predatory behaviour in a related spider species, showing that these vibrations do not simply function for species identity. These results suggest that male web-building spiders employ a phylogenetically conserved vibratory signal to ameliorate the risk of pre-copulatory cannibalism.

  2. 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...

  3. 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.

  4. On the endemic spider species of the genus Savigniorrhipis Wunderlich, 1992 (Araneae: Linyphiidae) in the Azores (Portugal), with description of a new species.

    PubMed

    Crespo, Luís Carlos; Bosmans, Robert; Cardoso, Pedro; Borges, Paulo A V

    2013-12-05

    Savigniorrhipis topographicus new species is described from the Azores. The synapomorphies of Savigniorrhipis are discussed along with the affinities of the genus within the Savignia-group. Given the extremely restricted and increasingly disturbed habitat, S. topographicus new species should be classified as Critically Endangered and its single forest habitat at Topo (São Jorge Island) should increase its current protection level to a strict nature reserve.

  5. Spiders as Classroom Pets

    ERIC Educational Resources Information Center

    Padilla, Michael J.

    1977-01-01

    Tips for raising and caring for spiders are given. Feeding habits, web spinning, and ecological relationships are discussed as possible areas for study during the school year. Directions for catching the spiders and making a home for them are included along with suggestions for food sources. (MA)

  6. 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…

  7. 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,…

  8. 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.

  9. 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.

  10. 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.

  11. 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.

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

    PubMed Central

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

    2012-01-01

    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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Spider webs: Damage control

    NASA Astrophysics Data System (ADS)

    Omenetto, Fiorenzo G.; Kaplan, David L.

    2012-04-01

    A study reveals that spider orb webs fail in a nonlinear fashion, owing to the hierarchical organization of the silk proteins. The discovery may serve as inspiration for engineers for the design of aerial, light-weight, robust architectures.

  19. 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.

  20. Brown recluse spider

    MedlinePlus

    ... However, they have been found in several large cities outside these areas. The brown recluse spider prefers ... other damp, moist areas. Alternative Names Loxosceles reclusa Images Arthropods, basic features Arachnids, basic features Brown recluse ...

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. The Jean Gutierrez spider mite collection

    PubMed Central

    Migeon, Alain

    2015-01-01

    Abstract 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. PMID:25878529

  7. 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.

  8. Silken toolkits: biomechanics of silk fibers spun by the orb web spider Argiope argentata (Fabricius 1775).

    PubMed

    Blackledge, Todd A; Hayashi, Cheryl Y

    2006-07-01

    Orb-weaving spiders spin five fibrous silks from differentiated glands that contain unique sets of proteins. Despite diverse ecological functions, the mechanical properties of most of these silks are not well characterized. Here, we quantify the mechanical performance of this toolkit of silks for the silver garden spider Argiope argentata. Four silks exhibit viscoelastic behaviour typical of polymers, but differ statistically from each other by up to 250% in performance, giving each silk a distinctive suite of material properties. Major ampullate silk is 50% stronger than other fibers, but also less extensible. Aciniform silk is almost twice as tough as other silks because of high strength and extensibility. Capture spiral silk, coated with aqueous glue, is an order of magnitude stretchier than other silks. Dynamic mechanical properties are qualitatively similar, but quantitatively vary by up to 300% among silks. Storage moduli are initially nearly constant and increase after fiber yield, whereas loss tangents reach maxima of 0.1-0.2 at the yield. The remarkable mechanical diversity of Argiope argentata silks probably results in part from the different molecular structures of fibers and can be related to the specific ecological role of each silk. Our study indicates substantial potential to customize the mechanics of bioengineered silks.

  9. 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.

  10. 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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    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

  13. 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

    2017-01-05

    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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Water-driven actuation of Ornithoctonus huwena spider silk fibers

    NASA Astrophysics Data System (ADS)

    Lin, Shuyuan; Zhu, Jia; Li, Xinming; Guo, Yang; Fang, Yaopeng; Cheng, Huanyu; Zhu, Hongwei

    2017-01-01

    Spider silk possesses remarkable mechanical properties and can lift weight effectively. Certain kinds of spider silk have unique response to liquid, especially water, because of their hydrophilic proteins, β-sheet characters, and surface structure. The Ornithoctonus huwena (O. huwena) spider is a unique species because it can be bred artificially and it spins silk whose diameter is in nanometer scale. In this work, we report the "shrink-stretch" behavior of the O. huwena spider silk fibers and show how they can be actuated by water to lift weight over long distance, at a fast speed, and with high efficiency. We further rationalize this behavior by analyzing the mechanical energy of the system. The lifting process is energy-efficient and environmentally friendly, allowing applications in actuators, biomimetic muscles, or hoisting devices.

  19. Contrasting responses of web-building spiders to deer browsing among habitats and feeding guilds.

    PubMed

    Takada, Mayura; Baba, Yuki G; Yanagi, Yosuke; Terada, Saeko; Miyashita, Tadashi

    2008-08-01

    We examined web-building spider species richness and abundance in forests across a deer density gradient to determine the effects of sika deer browsing on spiders among habitats and feeding guilds. Deer decreased the abundance of web-building spiders in understory vegetation but increased their abundance in the litter layer. Deer seemed to affect web-building spiders in the understory vegetation by reducing the number of sites for webs because vegetation complexity was positively correlated with spider density and negatively correlated with deer density. In contrast, the presence of vegetation just above the litter layer decreased the spider density, and deer exerted a negative effect on this vegetation, possibly resulting in an indirect positive effect on spider density. The vegetation just above the litter layer may be unsuitable as a scaffold for building webs if it is too flexible to serve as a reliable web support, and may even hinder spiders from building webs on litter. Alternatively, the negative effect of this vegetation on spiders in the litter may be as a result of reduced local prey availability under the leaves because of the reduced accessibility of aerial insects. The response to deer browsing on web-building spiders that inhabit the understory vegetation varied with feeding guild. Deer tended to affect web-invading spiders, which inhabit the webs of other spiders and steal prey, more heavily than other web-building spiders, probably because of the accumulated effects of habitat fragmentation through the trophic levels. Thus, the treatment of a particular higher-order taxon as a homogeneous group could result in misleading conclusions about the effects of mammalian herbivores.

  20. How informative are case studies of spider bites in the medical literature?

    PubMed

    Stuber, Marielle; Nentwig, Wolfgang

    2016-05-01

    We analyzed the reliability and information content of 134 medical case studies on spider bites, published in 91 journal articles. Overall, we found that only 22% of these studies fulfilled the criteria for a verified spider bite. This means that the majority of such case studies cannot be attributed to a given spider species and usually not even to a spider. Their scientific value is negligible, moreover, such publications are even dangerous because they suggest incorrect conclusions. Secondly, we found that such case studies usually do not follow an obvious structure and many details on the development of symptoms, therapy and healing process are widely lacking. So even for verified spider bites, the comparability of case studies is limited. We discuss the obvious failure of a reviewing process for case studies and give recommendations how to increase the currently low information content of medical case studies on spider bites.

  1. Acute kidney injury with pigment nephropathy following spider bite: a rarely reported entity in India.

    PubMed

    Golay, Vishal; Desai, Atul; Hossain, Aref; Roychowdhary, Arpita; Pandey, Rajendra

    2013-01-01

    Acute kidney injury (AKI) can be seen in tropical regions following bites of various venomous animals and insects. Renal failure is seen most commonly following the bite of spiders of the Loxosceles spp. Dermonecrosis, systemic inflammatory response, hemolysis, rhabdomyolysis, and direct venom-related effects are postulated as causes of AKI. We report a documented case of AKI with pigment nephropathy following the bite of a brown spider from a tropical region which is known to have many venomous animals but has no previous reports of AKI following spider bite. Whether this is due to absence of toxic spider species or underreporting needs to be determined.

  2. 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).

  3. 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

  4. Hey! A Brown Recluse Spider Bit Me!

    MedlinePlus

    ... in the Operating Room? Hey! A Brown Recluse Spider Bit Me! KidsHealth > For Kids > Hey! A Brown ... picó una reclusa parda! What's a Brown Recluse Spider? The brown recluse spider is one of the ...

  5. Spider minor ampullate silk proteins are constituents of prey wrapping silk in the cob weaver Latrodectus hesperus.

    PubMed

    La Mattina, Coby; Reza, Ryan; Hu, Xiaoyi; Falick, Arnold M; Vasanthavada, Keshav; McNary, Shannon; Yee, Russell; Vierra, Craig A

    2008-04-22

    Spiders spin high performance fibers with diverse biological functions and mechanical properties. Molecular and biochemical studies of spider prey wrapping silks have revealed the presence of the aciniform silk fibroin AcSp1-like. In our studies we demonstrate the presence of a second distinct polypeptide present within prey wrapping silk. Combining matrix-assisted laser desorption ionization tandem time-of-flight mass spectrometry and reverse genetics, we have isolated a novel gene called MiSp1-like and demonstrate that its protein product is a constituent of prey wrap silks from the black widow spider, Latrodectus hesperus. BLAST searches of the NCBInr protein database using the amino acid sequence of MiSp1-like revealed similarity to the conserved C-terminal domain of silk family members. In particular, MiSp1-like showed the highest degree of sequence similarity to the nonrepetitive C-termini of published orb-weaver minor ampullate fibroin molecules. Analysis of the internal amino acid sequence of the black widow MiSp1-like revealed polyalanine stretches interrupted by glycine residues and glycine-alanine couplets within MiSp1-like as well as repeats of the heptameric sequence AGGYGQG. Real-time quantitative PCR analysis demonstrates that the MiSp1-like gene displays a minor ampullate gland-restricted pattern of expression. Furthermore, amino acid composition analysis, coupled with scanning electron microscopy of raw wrapping silk, supports the assertion that minor ampullate silks are important constituents of black widow spider prey wrap silk. Collectively, our findings provide direct molecular evidence for the involvement of minor ampullate fibroins in swathing silks and suggest composite materials play an important role in the wrap attack process for cob-weavers.

  6. 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…

  7. 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).

  8. 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.

  9. 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 ...

  10. Spiders of medical importance in the Asia-Pacific: atracotoxin, latrotoxin and related spider neurotoxins.

    PubMed

    Nicholson, Graham M; Graudins, Andis

    2002-09-01

    1. The spiders of medical importance in the Asia-Pacific region include widow (family Theridiidae) and Australian funnel-web spiders (subfamily Atracinae). In addition, cupboard (family Theridiidae) and Australian mouse spiders (family Actinopodidae) may contain neurotoxins responsible for serious systemic envenomation. Fortunately, there appears to be extensive cross-reactivity of species-specific widow spider antivenom within the family Theridiidae. Moreover, Sydney funnel-web antivenom has been shown to be effective in the treatment of mouse spider envenomation. 2. alpha-Latrotoxin (alpha-LTx) appears to be the main neurotoxin responsible for the envenomation syndrome known as "latrodectism" following bites from widow spiders. This 120 kDa protein binds to distinct receptors (latrophilin 1 and neurexins) to induce neurotransmitter vesicle exocytosis via both Ca2+-dependent and -independent mechanisms, resulting in vesicle depletion. This appears to involve disruption to a process that normally inhibits vesicle fusion in the absence of Ca2+. Precise elucidation of the mechanism of action of alpha-LTx will lead to a major advancement in our understanding of vesicle exocytosis. 3. delta-Atracotoxins (delta-ACTX) are responsible for the primate-specific envenomation syndrome seen following funnel-web spider envenomation. These peptides induce spontaneous repetitive firing and prolongation of action potentials in excitable cells. This results from a hyperpolarizing shift of the voltage-dependence of activation and a slowing of voltage-gated Na+ channel inactivation. This action is due to voltage-dependent binding to neurotoxin receptor site-3 on insect and mammalian voltage-gated Na+ channels in a manner similar, but not identical, to scorpion alpha-toxins and sea anemone toxins. delta-Atracotoxins provide us with highly specific tools to study Na+ channel structure and function 4. omega- and Janus-faced ACTX, from funnel-web spider venom, are novel neurotoxins that

  11. Observations on germ band development in the cellar spider Pholcus phalangioides.

    PubMed

    Turetzek, Natascha; Prpic, Nikola-Michael

    2016-11-01

    Most recent studies of spider embryonic development have focused on representatives of the species-rich group of entelegyne spiders (over 80 % of all extant species). Embryogenesis in the smaller spider groups, however, is less well studied. Here, we describe the development of the germ band in the spider species Pholcus phalangioides, a representative of the haplogyne spiders that are phylogenetically the sister group of the entelegyne spiders. We show that the transition from radially symmetric embryonic anlage to the bilaterally symmetric germ band involves the accumulation of cells in the centre of the embryonic anlage (primary thickening). These cells then disperse all across the embryonic anlage. A secondary thickening of cells then appears in the centre of the embryonic anlage, and this thickening expands and forms the segment addition zone. We also confirm that the major part of the opisthosoma initially develops as a tube shaped structure, and its segments are then sequentially folded down on the yolk during inversion. This special mode of opisthosoma formation has not been reported for entelegyne spiders, but a more comprehensive sampling of this diverse group is necessary to decide whether this peculiarity is indeed lacking in the entelegyne spiders.

  12. 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.

  13. 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

  14. Host selection by a kleptobiotic spider

    NASA Astrophysics Data System (ADS)

    Hénaut, Yann; Delme, Juliette; Legal, Luc; Williams, Trevor

    2005-02-01

    Why do kleptobiotic spiders of the genus Argyrodes seem to be associated with spiders of the genus Nephila worldwide? Observations following introduction of experimental insect prey of different sizes and weights on to host webs revealed that: (1) small prey are more effectively retained on the web of Nephila clavipes than on the web of another common host, Leucauge venusta. (2) N. clavipes did not consume small prey that accumulated on the web whereas larger, heavier prey were enveloped and stored. (3) We observed clear partitioning of prey items between N. clavipes and Argyrodes spp.; diet selection by Argyrodes did not overlap with that of N. clavipes but closely overlapped with that of L. venusta. (4) L. venusta responds very quickly to prey impact whereas N. clavipes is slower, offering a temporal window of opportunity for Argyrodes foraging. (5) The ability of L. venusta to detect and respond to small items also means that it acts aggressively to Argyrodes spp., whereas N. clavipes does not. Consequently, food-acquisition behaviours of Argyrodes were clearly less risky with N. clavipes compared with L. venusta. We conclude that when a kleptobiotic organism has a choice of various host species, it will opt for the least risky host that presents the highest rate of availability of food items. The fact that Nephila species present such characteristics explains the worldwide association with Argyrodes kleptobiotic spiders.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. Extended spider cognition.

    PubMed

    Japyassú, Hilton F; Laland, Kevin N

    2017-02-07

    There is a tension between the conception of cognition as a central nervous system (CNS) process and a view of cognition as extending towards the body or the contiguous environment. The centralised conception requires large or complex nervous systems to cope with complex environments. Conversely, the extended conception involves the outsourcing of information processing to the body or environment, thus making fewer demands on the processing power of the CNS. The evolution of extended cognition should be particularly favoured among small, generalist predators such as spiders, and here, we review the literature to evaluate the fit of empirical data with these contrasting models of cognition. Spiders do not seem to be cognitively limited, displaying a large diversity of learning processes, from habituation to contextual learning, including a sense of numerosity. To tease apart the central from the extended cognition, we apply the mutual manipulability criterion, testing the existence of reciprocal causal links between the putative elements of the system. We conclude that the web threads and configurations are integral parts of the cognitive systems. The extension of cognition to the web helps to explain some puzzling features of spider behaviour and seems to promote evolvability within the group, enhancing innovation through cognitive connectivity to variable habitat features. Graded changes in relative brain size could also be explained by outsourcing information processing to environmental features. More generally, niche-constructed structures emerge as prime candidates for extending animal cognition, generating the selective pressures that help to shape the evolving cognitive system.

  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. Molecular spiders on a plane

    NASA Astrophysics Data System (ADS)

    Antal, Tibor; Krapivsky, P. L.

    2012-06-01

    Synthetic biomolecular spiders with “legs” made of single-stranded segments of DNA can move on a surface covered by single-stranded segments of DNA called substrates when the substrate DNA is complementary to the leg DNA. If the motion of a spider does not affect the substrates, the spider behaves asymptotically as a random walk. We study the diffusion coefficient and the number of visited sites for spiders moving on the square lattice with a substrate in each lattice site. The spider's legs hop to nearest-neighbor sites with the constraint that the distance between any two legs cannot exceed a maximal span. We establish analytic results for bipedal spiders, and investigate multileg spiders numerically. In experimental realizations legs usually convert substrates into products (visited sites). The binding of legs to products is weaker, so the hopping rate from the substrates is smaller. This makes the problem non-Markovian and we investigate it numerically. We demonstrate the emergence of a counterintuitive behavior—the more spiders are slowed down on unvisited sites, the more motile they become.

  2. Cross-reactivity of Sydney funnel-web spider antivenom: neutralization of the in vitro toxicity of other Australian funnel-web (Atrax and Hadronyche) spider venoms.

    PubMed

    Graudins, A; Wilson, D; Alewood, P F; Broady, K W; Nicholson, G M

    2002-03-01

    Australian funnel-web spiders are recognized as one of the most venomous spiders to humans world-wide. Funnel-web spider antivenom (FWS AV) reverses clinical effects of envenomation from the bite of Atrax robustus and a small number of related Hadronyche species. This study assessed the in vitro efficacy of FWS AV in neutralization of the effects of funnel-web spider venoms, collected from various locations along the eastern seaboard of Australia, in an isolated chick biventer cervicis nerve-muscle preparation. Venoms were separated by SDS-PAGE electrophoresis to compare protein composition and transblotted for Western blotting and incubation with FWS AV.SDS-PAGE of venoms revealed similar low and high molecular weight protein bands. Western blotting with FWS AV showed similar antivenom binding with protein bands in all the venoms tested. Male funnel-web spider venoms (7/7) and female venoms (5/10) produced muscle contracture and fasciculation when applied to the nerve-muscle preparation. Venom effects were reversed by subsequent application of FWS AV or prevented by pretreatment of the preparation with antivenom.FWS AV appears to reverse the in vitro toxicity of a number of funnel-web spider venoms from the eastern seaboard of Australia. FWS AV should be effective in the treatment of envenomation from most, if not all, species of Australian funnel-web spiders.

  3. 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).

  4. Reversible myocarditis after spider bite

    PubMed Central

    Kara, Hasan; Ak, Ahmet; Bayir, Aysegul; Avci, Ahmet

    2013-01-01

    Black widow spiders (Latrodectus tredecimguttatus) are poisonous spiders endemic in Turkey. Latrodectus bites may cause myocarditis with increased cardiac enzymes. We treated two men (aged 20 and 33 years) who had myocarditis after black spider bites with leucocytosis and elevated levels of troponin I, creatine kinase and creatine kinase-MB fraction. Both patients had normal results on an ECG, and one patient had abnormal echocardiography with minimal left ventricular wall movement disorder. Both patients were hospitalised in the intensive care unit and treated with intravenous fluids, analgesics, spasmolytic drugs, tetanus prophylaxis and cardiac monitoring. The levels of troponin I, creatine kinase and creatine kinase-MB fraction improved, and the patients were discharged home on the third and fifth hospital day without complications. Myocarditis after a Latrodectus bite is rare, but may be associated with serious complications. Therefore, in regions endemic with Latrodectus spiders, prudent treatment of spider bites may include cardiac evaluation and monitoring. PMID:23572268

  5. Reversible myocarditis after spider bite.

    PubMed

    Kara, Hasan; Ak, Ahmet; Bayir, Aysegul; Avci, Ahmet

    2013-04-08

    Black widow spiders (Latrodectus tredecimguttatus) are poisonous spiders endemic in Turkey. Latrodectus bites may cause myocarditis with increased cardiac enzymes. We treated two men (aged 20 and 33 years) who had myocarditis after black spider bites with leucocytosis and elevated levels of troponin I, creatine kinase and creatine kinase-MB fraction. Both patients had normal results on an ECG, and one patient had abnormal echocardiography with minimal left ventricular wall movement disorder. Both patients were hospitalised in the intensive care unit and treated with intravenous fluids, analgesics, spasmolytic drugs, tetanus prophylaxis and cardiac monitoring. The levels of troponin I, creatine kinase and creatine kinase-MB fraction improved, and the patients were discharged home on the third and fifth hospital day without complications. Myocarditis after a Latrodectus bite is rare, but may be associated with serious complications. Therefore, in regions endemic with Latrodectus spiders, prudent treatment of spider bites may include cardiac evaluation and monitoring.

  6. 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...

  7. Can field-scale habitat diversification enhance the biocontrol potential of spiders?

    PubMed

    Samu, Ferenc

    2003-04-01

    The study investigated the effect of strip management in alfalfa on the abundance and diversity of spiders. In strip management, narrow strips were left unmown in the crop, which were then shifted at next mowing. In an experimental field, out of the six 50 x 50-m blocks, three received strip management and three were managed traditionally (ie the whole block was mown). Our main hypothesis was that unmown strips will contain a more diverse and abundant spider assemblage, which will increase spider numbers in the mown parts of the crop. Over the 3 years of the study, unmown strips contained a spider assemblage of more than 50% higher abundance than in control alfalfa. Species diversity was also greater in the strips, and the presence of specific indicator species could be shown. We found that five dominant species comprised over 75% of spiders in the strips, and they were the same species as those that are dominant in alfalfa, where they represent 85% of all spiders. In contrast, a neighbouring meadow, which was a control in the study, also had high diversity, but different dominant species. The main result of the experiment was negative in that elevated abundance of spiders in unmown strips did not raise spider numbers in the mown strips of alfalfa, where abundance was only marginally higher than in the control alfalfa. We can speculate that better ecological conditions in unmown strips attract and conserve spiders from neighbouring areas and from the crop at mowing. We suggest that if diversification is more interspersed within the crop, we have a higher chance of increasing the number of natural enemies and bringing them closer to pests, so that they can interact more intensively.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. An investigation of spider fauna of olive orchards in northern part of Iran.

    PubMed

    Ghavami, Sahra; Mohammad, Ahmadi Damghan; Saeid, Soody; Saeid, Ghanad amooz; Saeb, Javadi

    2007-08-01

    The current study investigates spider fauna of olive orchards in Guilan, Ghazvin, Mazandaran, Zanjan and Golestan provinces during 2002-2003. Spiders were collected from branches, leaves, trunks, on the ground and under the stones and grasses by Steiner and Baggiolini method, bottle, aspirator, pitfall trap, pans and insect net and transfered to laboratory and classified in 45 species and 46 genera belonged to 18 families. Twenty five species, 9 genera and 2 families are reported for the first time of olive orchards.

  14. Reverse positional orientation in a neotropical orb-web spider, Verrucosa arenata.

    PubMed

    Rao, Dinesh; Ceballos Fernandez, Oscar; Castañeda-Barbosa, Ernesto; Díaz-Fleischer, Francisco

    2011-08-01

    Most orb-web spiders face downwards in the web. A downward orientation has been proposed to be the optimal strategy because spiders run faster downwards and thus can catch prey quicker. Consequently, orb-web spiders also extend their web in the lower part, leading to top-down web asymmetry. Since the majority of orb-web spiders face downwards, it has been difficult to test the effect of orientation on prey capture and web asymmetry. In this study, we explored the influence of reverse orientation on foraging efficiency and web asymmetry in Verrucosa arenata, a neotropical orb-web spider that faces upwards in the web. We show that reverse orientation does not imply reverse web asymmetry in this species. V. arenata spiders captured more prey in the lower part of the web but more prey per area on the upper part. The average running speeds of spiders did not differ between upward and downward running, but heavier spiders took longer to capture prey while running upwards. We discuss these findings in the context of foraging efficiency and web asymmetry.

  15. Reverse positional orientation in a neotropical orb-web spider, Verrucosa arenata

    NASA Astrophysics Data System (ADS)

    Rao, Dinesh; Fernandez, Oscar Ceballos; Castañeda-Barbosa, Ernesto; Díaz-Fleischer, Francisco

    2011-08-01

    Most orb-web spiders face downwards in the web. A downward orientation has been proposed to be the optimal strategy because spiders run faster downwards and thus can catch prey quicker. Consequently, orb-web spiders also extend their web in the lower part, leading to top-down web asymmetry. Since the majority of orb-web spiders face downwards, it has been difficult to test the effect of orientation on prey capture and web asymmetry. In this study, we explored the influence of reverse orientation on foraging efficiency and web asymmetry in Verrucosa arenata, a neotropical orb-web spider that faces upwards in the web. We show that reverse orientation does not imply reverse web asymmetry in this species. V. arenata spiders captured more prey in the lower part of the web but more prey per area on the upper part. The average running speeds of spiders did not differ between upward and downward running, but heavier spiders took longer to capture prey while running upwards. We discuss these findings in the context of foraging efficiency and web asymmetry.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. A new species of spider fly in the genus Sabroskya Schlinger from Malawi, with a key to Acrocerinae world genera (Diptera, Acroceridae).

    PubMed

    Winterton, Shaun L; Gillung, Jéssica P

    2012-01-01

    In this paper we diagnose the genus Sabroskya Schlinger, 1960 and describe Sabroskya schlingerisp. n. from Malawi. We also provide dichotomous keys to species of Sabroskya and to world genera of the subfamily Acrocerinae, both extant and extinct.

  1. 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

  2. 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

  3. Small molecules from spiders used as chemical probes.

    PubMed

    Olsen, Christian A; Kristensen, Anders S; Strømgaard, Kristian

    2011-11-25

    Spiders are important species in ecological systems and as major predators of insects they are endowed with a plethora of low-molecular-weight natural products having intriguing biological activities. The isolation and biological characterization of these entities are well established, however, only very recently have these compounds been used as templates for the design, synthesis, and biological evaluation of synthetic analogues. In contrast, the investigation of compounds responsible for chemical communication between spiders is far less developed, but recently new light has been shed onto the area of pheromones and allomones from spiders. Herein, we recapitulate these recent results, put them into perspective with previous findings, and provide an outlook for future studies of these chemotypes.

  4. '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.

  5. '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.

  6. Host specificity and temporal and seasonal shifts in host preference of a web-spider parasitoid Zatypota percontatoria.

    PubMed

    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.

  7. 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

  8. 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.

  9. Global patterns of guild composition and functional diversity of spiders.

    PubMed

    Cardoso, Pedro; Pekár, Stano; Jocqué, Rudy; Coddington, Jonathan A

    2011-01-01

    The objectives of this work are: (1) to define spider guilds for all extant families worldwide; (2) test if guilds defined at family level are good surrogates of species guilds; (3) compare the taxonomic and guild composition of spider assemblages from different parts of the world; (4) compare the taxonomic and functional diversity of spider assemblages and; (5) relate functional diversity with habitat structure. Data on foraging strategy, prey range, vertical stratification and circadian activity was collected for 108 families. Spider guilds were defined by hierarchical clustering. We searched for inconsistencies between family guild placement and the known guild of each species. Richness and abundance per guild before and after correcting guild placement were compared, as were the proportions of each guild and family between all possible pairs of sites. Functional diversity per site was calculated based on hierarchical clustering. Eight guilds were discriminated: (1) sensing, (2) sheet, (3) space, and (4) orb web weavers; (5) specialists; (6) ambush, (7) ground, and (8) other hunters. Sixteen percent of the species richness corresponding to 11% of all captured individuals was incorrectly attributed to a guild by family surrogacy; however, the correlation of uncorrected vs. corrected guilds was invariably high. The correlation of guild richness or abundances was generally higher than the correlation of family richness or abundances. Functional diversity was not always higher in the tropics than in temperate regions. Families may potentially serve as ecological surrogates for species. Different families may present similar roles in the ecosystems, with replacement of some taxa by other within the same guild. Spiders in tropical regions seem to have higher redundancy of functional roles and/or finer resource partitioning than in temperate regions. Although species and family diversity were higher in the tropics, functional diversity seems to be also influenced by

  10. 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.

  11. A new species of spider fly in the genus Sabroskya Schlinger from Malawi, with a key to Acrocerinae world genera (Diptera, Acroceridae)

    PubMed Central

    Winterton, Shaun L.; Gillung, Jéssica P.

    2012-01-01

    Abstract In this paper we diagnose the genus Sabroskya Schlinger, 1960 and describe Sabroskya schlingeri sp. n. from Malawi. We also provide dichotomous keys to species of Sabroskya and to world genera of the subfamily Acrocerinae, both extant and extinct. PMID:22423193

  12. On the synonymy of two wolf spider species of the genus Alopecosa (Araneae, Lycosidae) from the steppe zone of Russia.

    PubMed

    Azarkina, Galina N; Esyunin, Sergei L; Kuz'min, Evgeniy A; Marusik, Yuri M

    2016-12-07

    Alopecosa atypica Ponomarev, 2008 is known from the holotype male collected in Western Kazakhstan. Here we synonymize it with A. cronebergi (Thorell, 1875), which was described from two syntype females from the Volga River and Daghestan. This species is redescribed in detail and its distribution is shown to be restricted to Russia and Ukraine, and previous records from Hungary are probably mistaken.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Molecular characterization and evolutionary study of spider tubuliform (eggcase) silk protein.

    PubMed

    Tian, Maozhen; Lewis, Randolph V

    2005-06-07

    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.

  18. 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

  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. 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.

  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. Morphology of the tracheal system of camel spiders (Chelicerata: Solifugae) based on micro-CT and 3D-reconstruction in exemplar species from three families.

    PubMed

    Franz-Guess, Sandra; Klußmann-Fricke, Bastian-Jesper; Wirkner, Christian S; Prendini, Lorenzo; Starck, J Matthias

    2016-09-01

    We studied the tracheal system of exemplar species representing three families of Solifugae Sundevall, 1833, i.e., Galeodes granti Pocock, 1903, Ammotrechula wasbaueri Muma, 1962 and Eremobates sp., using μCT-imaging and 3D-reconstruction. This is the first comparative study of the tracheal system of Solifugae in 85 years and the first using high-resolution nondestructive methods. The tracheal system was found to be structurally similar in all three species, with broad major tracheae predominantly in the prosoma as well as anastomoses (i.e., connections between tracheal branches from different stigmata) in the prosoma and opisthosoma. Differences among the three species were observed in the presence or absence of cheliceral air sacs, the number of tracheae supplying the heart, and the ramification of major tracheae in the opisthosoma. The structure of the tracheal system with its extensive branches and some anastomoses is assumed to aid rapid and efficient gas exchange in the respiratory tissues of these active predators. The large diameter of cheliceral tracheae (air sacs) of taxa with disproportionally heavier chelicerae suggests a role in weight reduction, enabling solifuges to reach greater speeds during predation. The air sacs may also permit more rapid and efficient gaseous exchange, necessary to operate the musculature of these structures, thereby improving their use for predation in an environment where prey is scarce.

  3. Distribution of the brown recluse spider (Araneae: Sicariidae) in Georgia with comparison to poison center reports of envenomations.

    PubMed

    Vetter, Richard S; Hinkle, Nancy C; Ames, Lisa M

    2009-01-01

    Georgia is on the southeastern margin of the native range of the brown recluse spider, Loxosceles reclusa Gertsch and Mulaik. The brown recluse is not a common Georgia spider and has limited distribution in the state. Using recent submissions, previously published records, and examination of museum specimens, we document the spider's presence in 31 (19.5%) of Georgia's 159 counties, with almost all being found in the northern portion. The spider was collected almost exclusively north of the Fall Line (a transition zone separating the Piedmont and the Coastal Plain geological provinces). Only two locations in the southern Coastal Plain province produced L. reclusa specimens; these southern finds are considered spiders that were transported outside their range. There were six finds of the non-native world tramp species, L. rufescens (Dufour), three south of the Fall Line. In conspicuous contrast, over a 5-yr period, a Georgia poison center database recorded 963 reports of brown recluse spider bites from 103 counties. These figures greatly outnumber the historic verifications of brown recluses in the state for both specimen quantity and county occurrence, indicating improbable spider involvement and the overdiagnosis of bites. In the southern half of the state, medical diagnoses of brown recluse spider bites have virtually zero probability of being correct. Bite diagnoses should be made with caution in north Georgia given the spider's spotty distribution with low frequency of occurrence.

  4. A survey of the spider family Nesticidae (Arachnida, Araneae) in Asia and Madagascar, with the description of forty-three new species

    PubMed Central

    Lin, Yucheng; Ballarin, Francesco; Li, Shuqiang

    2016-01-01

    Abstract Forty-three new species of Nesticidae are described from China, Indonesia, Philippines, Singapore, Thailand, Vietnam and Madagascar, and two new junior synonyms are suggested. A new genus, Speleoticus gen. n., is described with Nesticus navicellatus Liu & Li, 2013 as the type species, and four species are transferfed from Nesticus, i.e., Speleoticus globosus (Liu & Li, 2013), comb. n., Speleoticus libo (Chen & Zhu, 2005), comb. n., Speleoticus navicellatus (Liu & Li, 2015), comb. n. and Speleoticus uenoi (Yaginuma, 1972), comb. n. The new species described in this paper belong to four genera and are: Hamus cornutus sp. n. (♂♀), Hamus kangdingensis sp. n. (♂), Hamus luzon sp. n. (♀), Hamus mangunensis sp. n. (♂), Nescina kohi sp. n. (♂♀), Nesticella baiseensis sp. n. (♂♀), Nesticella baobab sp. n. (♂), Nesticella caeca sp. n. (♂♀), Nesticella chongqing sp. n. (♀), Nesticella dazhuangensis sp. n. (♂♀), Nesticella fuliangensis sp. n. (♂♀), Nesticella gazuida sp. n. (♀), Nesticella gongshanensis sp. n. (♀), Nesticella griswoldi sp. n. (♂♀), Nesticella hongheensis sp. n. (♂♀), Nesticella huomachongensis sp. n. (♂♀), Nesticella jingpo sp. n. (♀), Nesticella kaohsiungensis sp. n. (♂♀), Nesticella lisu sp. n. (♂♀), Nesticella liuzhaiensis sp. n. (♀), Nesticella nandanensis sp. n. (♂♀), Nesticella phami sp. n. (♂♀), Nesticella potala sp. n. (♀), Nesticella qiaoqiensis sp. n. (♀), Nesticella qiongensis sp. n. (♂♀), Nesticella robusta sp. n. (♂♀), Nesticella rongtangensis sp. n. (♂), Nesticella sanchaheensis sp. n. (♂♀), Nesticella sulawesi sp. n. (♀), Nesticella sumatrana sp. n. (♂), Nesticella tibetana sp. n. (♂♀), Nesticella vanlang sp. n. (♀), Nesticella wanzaiensis sp. n. (♂♀), Nesticella xiongmao sp. n. (♂♀), Nesticella xixia sp. n. (♂♀), Nesticella yanbeiensis sp. n. (♂♀), Nesticella yao sp. n. (♀), Nesticella zhiyuani sp. n. (

  5. Deer herbivory reduces web-building spider abundance by simplifying forest vegetation structure.

    PubMed

    Roberson, Elizabeth J; Chips, Michael J; Carson, Walter P; Rooney, Thomas 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.

  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. 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.

  8. 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

  9. 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.

  10. 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.

  11. Sclerotherapy of Varicose Veins and Spider Veins

    MedlinePlus

    ... Index A-Z Sclerotherapy of Varicose Veins and Spider Veins Sclerotherapy uses injections from a very fine, ... Sclerotherapy? What is Sclerotherapy of Varicose Veins and Spider Veins? Sclerotherapy is a minimally invasive treatment used ...

  12. 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.

  13. Contribution to the knowledge of pathogenic fungi of spiders in Argentina. Southernmost record in the world.

    PubMed

    Manfrino, Romina G; González, Alda; Barneche, Jorge; Tornesello Galván, Julieta; Hywell-Jones, Nigel; López Lastra, Claudia C

    2017-03-23

    The aim of this study was to identify entomopathogenic fungi infecting spiders (Araneae) in a protected area of Buenos Aires province, Argentina. The Araneae species identified was Stenoterommata platensis. The pathogens identified were Lecanicillium aphanocladii Zare & W. Gams, Purpureocillium lilacinum (Thom) Luangsa-ard, Houbraken, Hywel Jones & Samson and Ophiocordyceps caloceroides (Berk & M.A. Curtis). This study constitutes the southernmost records in the world and contributes to expanding the knowledge of the biodiversity of pathogenic fungi of spiders in Argentina.

  14. Optics of Spider Sticky Orb Webs

    DTIC Science & Technology

    2011-01-01

    silks of Australian orb web weaving spiders . Studies of both 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 06-10-2011 13. SUPPLEMENTARY NOTES The...thin film effects as the primary causes. We report systematic studies carried out using the silks of Australian orb web weaving spiders . Studies of... spiders . Studies of both white light and laser light scattering/propagation by natural spider silks have definitively determined the primary cause

  15. 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

  16. 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

  17. 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

  18. Hey! A Black Widow Spider Bit Me!

    MedlinePlus

    ... dientes Video: Getting an X-ray Hey! A Black Widow Spider Bit Me! KidsHealth > For Kids > Hey! A Black ... Me picó una araña viuda negra! What's a Black Widow Spider? The black widow spider is one of the ...

  19. One species or several? Discordant patterns of geographic variation between allozymes and mtDNA sequences among spiders in the genus Metepeira (Araneae: Araneidae).

    PubMed

    Piel, W H; Nutt, K J

    2000-06-01

    Paradoxically, an allozyme study of Metepeira "spinipes" (sensu lato) demonstrated extensive gene flow among four populations whose members are nevertheless morphologically and behaviorally distinct. Initially, the authors tentatively concluded that the populations exhibited panmixis and suggested that local environmental effects accounted for the apparent morphological and behavioral differences. However, they later concluded that such differences were too great to be accounted for by the environment alone and that the four populations actually represented three different species. To confirm that the allozyme results were, in fact, artifactual, we reexamined the relationships among these populations by sequencing a portion of the 12S mtDNA ribosomal subunit. In contrast to the allozyme result, our results demonstrate good agreement between patterns of genetic and morphological/behavioral variation. We suggest (1) that the allozyme allele frequencies are homogenized by balancing selection, not gene flow as was previously concluded, and therefore (2) that this study provides another instance in which inferences about population structures from allozyme data are misleading.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Polarized light detection in spiders.

    PubMed

    Dacke, M; Doan, T A; O'Carroll, D C

    2001-07-01

    We describe here the detection of polarized light by the simple eyes of spiders. Using behavioural, morphological, electrophysiological and optical studies, we show that spiders have evolved two different mechanisms to resolve the e-vector of light. Wolf spiders (Lycosidae), are able to turn in response to rotation of a polarized pattern at the zenith of their visual fields, and we also describe a strip in the ventral retina of the principal (anterio-median) eyes that views this location and has receptors tiered into two layers. This provides each pair of receptors with a similar optical solution to that provided by the 'dorsal rim area' of the insect compound eye. In contrast, gnaphosid spiders have evolved a pair of lensless secondary eyes for the detection of polarized light. These two eyes, each sensitive to orthogonal directions of polarization, are perfectly designed to integrate signals from the larger part of the sky and cooperate to analyse the polarization of light. Built-in polarizers help to improve signal purity. Similar organisation in the eyes of several other spider families suggests that these two mechanisms are not restricted to only a few families.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. Toxicity of the venom of Latrodectus (Araneae: Theridiidae) spiders from different regions of Argentina and neutralization by therapeutic antivenoms.

    PubMed

    de Roodt, Adolfo Rafael; Lanari, Laura Cecilia; Laskowicz, Rodrigo Daniel; Costa de Oliveira, Vanessa; Irazu, Lucia Elvira; González, Alda; Giambelluca, Luis; Nicolai, Néstor; Barragán, Javier Hugo; Ramallo, Leticia; López, Raúl Alfredo; Lopardo, Jorge; Jensen, Oscar; Larrieu, Edmundo; Calabró, Arnoldo; Vurcharchuc, Miriam Guadalupe; Lago, Néstor Rubén; García, Susana Isabel; de Titto, Ernesto Horacio; Damín, Carlos Fabián

    2017-05-01

    "Black widow" spiders belong to the genus Latrodectus and are one of the few spiders in the world whose bite can cause severe envenomation in humans and domestic animals. In Argentina, these spiders are distributed throughout the country and are responsible for the highest number of bites by spiders of toxicological sanitary interest. Here, we studied the toxicity and some biochemical and immunochemical characteristics of eighteen venom samples from Latrodectus spiders from eight different provinces of Argentina, and the neutralization of some of these samples by two therapeutic antivenoms used in the country for the treatment of envenomation and by a anti-Latrodectus antivenom prepared against the venom of Latrodectus mactans from Mexico. We observed important toxicity in all the samples studied and a variation in the toxicity of samples, even in those from the same region and province and even in the same Latrodectus species from the same region. The therapeutic antivenoms efficiently neutralized all the venoms studied.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Cloning and Structure of Different Types of Spider Silk

    DTIC Science & Technology

    1991-11-10

    December 1, 1988 RESEARCH OBJECTIVES: Clone, sequence and express dragline silk protein from Nephila Clavipes and compare the sequence to clones of the...studies was to obtain sufficient quantities of a single pure type of silk. Spiders were obtained from Florida( Nephila clavipes) or collected locally...and on each different batch of silk. The compositions were similar in every case to those published for that species( Nephila ) or for a closely

  15. Investigation fauna and density of population of spiders in the desert and pomegranate orchards in Tehran and Semnan provinces.

    PubMed

    Ghavami, Sahra

    2008-03-01

    The present study was carried out to consideration the spider's fauna and abundance of spiders in the desert and pomegranate orchards in Tehran and Semnan provinces, during 2007. Specimens were collected from desert and pomegranate orchards by pitfall trap, shaking tree, pans, bottle and aspirator and were taken to the laboratory after labeling. A total of 1231 specimens were classified in 45 species and 36 genera belonged to 17 families. Among them 4 spider species were new for Iranian spider fauna. The families Lycosidae, Linyphiidae, Gnaphosidae and Theridiidae had height population in the study areas. Specimens were immature in the winter and spring and they were adult in the summer. The dominant species in all of study regions was Pardosa agrestis (Westring).

  16. Spider silk: Webs measure up

    NASA Astrophysics Data System (ADS)

    Qin, Zhao; Buehler, Markus J.

    2013-03-01

    The complete elastic response of a spider's orb web has been quantified by non-invasive light scattering, revealing important insights into the architecture, natural material use and mechanical properties of the web. This knowledge advances our understanding of the prey-catching process and the role of supercontraction therein.

  17. 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…

  18. Spider pheromones - a structural perspective.

    PubMed

    Schulz, Stefan

    2013-01-01

    Spiders use pheromones for sexual communication, as do other animals such as insects. Nevertheless, knowledge about their chemical structure, function, and biosynthesis is only now being unraveled. Many studies have shown the existence of spider pheromones, but the responsible compounds have been elucidated in only a few cases. This review focuses on a structural approach because we need to know the involved chemistry if we are to understand fully the function of a pheromonal communication system. Pheromones from members of the spider families Pholcidae, Araneidae, Linyphiidae, Agenelidae, and Ctenidae are currently being identified and will be discussed in this review. Some of these compounds belong to compound classes not known from other arthropod pheromones, such as citric acid derivatives or acylated amino acids, whereas others originate from more common fatty acid metabolism. Their putative biosynthesis, their function, and the identification methods used will be discussed. Furthermore, other semiochemicals and the chemistry of apolar surface lipids that potentially might be used by spiders for communication are described briefly.

  19. 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.

  20. A Proteomics and Transcriptomics Investigation of the Venom from the Barychelid Spider Trittame loki (Brush-Foot Trapdoor)

    PubMed Central

    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.

    2013-01-01

    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. PMID:24351713

  1. Identification and synthesis of novel biomaterials based on spider structural silk fibers

    NASA Astrophysics Data System (ADS)

    Hsia, Yang; Gnesa, Eric; Tang, Simon; Jeffery, Felicia; Geurts, Paul; Zhao, Liang; Franz, Andreas; Vierra, Craig

    2011-11-01

    The diversity in function and mechanical behavior of spider silks, and the ability to produce these silks recombinantly, have tremendous potential in creating a new class of biomimetic materials. Here we investigate the structural and mechanical properties of pyriform silks from the golden orb-weaver, Nephila clavipes. Nanoscale indentation measurements using atomic force microscopy on natural pyriform silk suggests that this biomaterial has high toughness that may be suitable for dissipating high amounts of mechanical energy. We also observed the occurrence of highly organized nanocrystals within the pyriform silk fibers that may contribute to the remarkable energy dissipation capability of these silks. It has been demonstrated that poly-(Gly-Ala) and poly-Ala stretches within the internal block repeat modules of dragline silk fibroins form nanocrystals, and these nanocrystalline structures may be responsible for the high extensibility of the dragline silks. In contrast, amino acid sequence analysis shows that PySp2 does not contain the same motifs. In the absence of poly-(Gly-Ala) and poly-Ala repeats, we hypothesized that PySp2 contains new protein motifs sufficient to polymerize into functional structures. To investigate the functional contributions of these novel motifs during pyriform fiber formation, we expressed different recombinant PySp2 fibroins with various segments spanning its block repeat units. We demonstrate that PySp2 recombinant proteins with the Pro-rich sub-block domain (PXP motifs, where X= sub-set of the amino acids A, L, or R) and/or the Ser + Gln + Ala-rich sub-block domain (QQSSVAQS motifs) are sufficient for artificial fiber formation. Moreover, we show that recombinant PySp2 proteins that contain a single block repeat unit can self-assemble into foam-like nanostructures. Collectively, our findings support the use of PySp2 recombinant proteins for a wide range of biomimetic materials with morphologies ranging from fibers to porous

  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. 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.

  4. Upper eyelid necrosis and reconstruction after spider byte: case report and review of the literature.

    PubMed

    Ribuffo, D; Serratore, F; Famiglietti, M; Greco, M; Fois, F; Atzori, L; Pau, M; Aste, N

    2012-03-01

    Spider bites are not very common, especially in the Mediterranean area, and those affecting the ocular-palpebral region involving reconstructive surgery are particularly rare. In May 2010, the case of a Caucasian 24-year-old female patient was brought to the attention of the Dermatology Department, University of Cagliari, Italy. The patient reported she woke up feeling an intense pain with itching and that also she had noticed a spider of an unknown species on her bed. The dermatosis had affected the right orbital region, where there was a considerable red and violet erythema and a hard edema, not foldable. When the necrosis appeared the patient was treated at the Plastic Surgery Unit where she underwent a reconstruction of the eyelid with a full thickness skin graft from the retroauricular area. The post-operative course was regular with a perfect in-take of the skin graft. When the patient was discharged she was sent to an Entomological University Centre to identify the spider species and the possible venom which caused the skin lesion. The spider which caused the injury has been a Loxosceles rufescens (Dufour, 1820). Loxoscelism is a necrotic arachnoidism caused by the poisonous bite of spiders belonging to the Loxosceles species. It is very important to identify what sort of lesion it is and to treat it in a combined way in order to choose the proper timing for surgery to avoid damages to the eyelid functioning.

  5. 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

  6. 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.

  7. Comparing the rheology of native spider and silkworm spinning dope.

    PubMed

    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.

  8. 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

  9. Management intensity and vegetation complexity affect web-building spiders and their prey.

    PubMed

    Diehl, Eva; Mader, Viktoria L; Wolters, Volkmar; Birkhofer, Klaus

    2013-10-01

    Agricultural management and vegetation complexity affect arthropod diversity and may alter trophic interactions between predators and their prey. Web-building spiders are abundant generalist predators and important natural enemies of pests. We analyzed how management intensity (tillage, cutting of the vegetation, grazing by cattle, and synthetic and organic inputs) and vegetation complexity (plant species richness, vegetation height, coverage, and density) affect rarefied richness and composition of web-building spiders and their prey with respect to prey availability and aphid predation in 12 habitats, ranging from an uncut fallow to a conventionally managed maize field. Spiders and prey from webs were collected manually and the potential prey were quantified using sticky traps. The species richness of web-building spiders and the order richness of prey increased with plant diversity and vegetation coverage. Prey order richness was lower at tilled compared to no-till sites. Hemipterans (primarily aphids) were overrepresented, while dipterans, hymenopterans, and thysanopterans were underrepresented in webs compared to sticky traps. The per spider capture efficiency for aphids was higher at tilled than at no-till sites and decreased with vegetation complexity. After accounting for local densities, 1.8 times more aphids were captured at uncut compared to cut sites. Our results emphasize the functional role of web-building spiders in aphid predation, but suggest negative effects of cutting or harvesting. We conclude that reduced management intensity and increased vegetation complexity help to conserve local invertebrate diversity, and that web-building spiders at sites under low management intensity (e.g., semi-natural habitats) contribute to aphid suppression at the landscape scale.

  10. 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.

  11. 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.

  12. Biomechanical characterization of spider webs.

    PubMed

    Das, Rakesh; Kumar, Amit; Patel, Anurag; Vijay, Sahil; Saurabh, Shashank; Kumar, Navin

    2017-03-01

    In light of recent focus on the behaviour of the natural structures for revolutionary technological growth, spider web seems to have seized considerable attention of product designer due to its amazing behaviour. In present work, mechanism behind the structural integrity of the spider web along with the materialistic analysis of its constituent silk threads has been extensively investigated. The nanoindentation tool both in static and dynamic mode has been utilized for complete analysis of the mechanical behaviour of the spiral and radial threads separately. Both the average elastic modulus and hardness of the radial silk thread is higher than the spiral silk thread which reveals the radial silk thread is the major structural component of the web. The sustainability of spider webs under storm, windy conditions and during the impact of pray has been investigated under dynamic conditions. The radial silk thread exhibits elastic like response and the spiral silk thread exhibits viscous like response in a wide frequency range (1-200Hz). The damping characteristic of the radial and spiral silk threads, an important parameter to investigate the energy dissipation properties of the materials has also been investigated in windy conditions.

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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…

  19. 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

  20. 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…

  1. Desiccation resistance reflects patterns of microhabitat choice in a Central American assemblage of wandering spiders.

    PubMed

    Lapinski, Witold; Tschapka, Marco

    2014-08-01

    The lowland rainforest of northeastern Costa Rica harbours an assemblage of large wandering spider species belonging to three habitat subguilds: (1) semi-aquatic, (2) forest ground dwelling and (3) vegetation dwelling. We hypothesized that desiccation resistance should differ among species preferring different microhabitats and the associated microclimate. Desiccation resistance was assessed by: (1) measuring water loss rates of the spiders under relatively dry experimental conditions, and (2) recording desiccation susceptibility, i.e. the reactions of the spiders to a relatively dry environment. High water loss rates and desiccation susceptibility of the semi-aquatic and forest-ground-dwelling subguilds clearly mirrored the relatively humid microclimate of the understory. Significantly lower water loss rates and desiccation susceptibility of the vegetation-dwelling species reflected the highly variable, often dry and hot conditions of the rainforest canopy and forest edge habitats. Vegetation-dwelling wandering spiders are therefore physiologically better adapted to dry conditions than the semi-aquatic and forest-ground-dwelling species. The results illustrate the significance of physiological characteristics for explaining both species-specific habitat use and, in a larger context, niche partitioning within a community.

  2. Spider dragline silk: correlated and mosaic evolution in high-performance biological materials.

    PubMed

    Swanson, Brook O; Blackledge, Todd A; Summers, Adam P; Hayashi, Cheryl Y

    2006-12-01

    The evolution of biological materials is a critical, yet poorly understood, component in the generation of biodiversity. For example, the diversification of spiders is correlated with evolutionary changes in the way they use silk, and the material properties of these fibers, such as strength, toughness, extensibility, and stiffness, have profound effects on ecological function. Here, we examine the evolution of the material properties of dragline silk across a phylogenetically diverse sample of species in the Araneomorphae (true spiders). The silks we studied are generally stronger than other biological materials and tougher than most biological or man-made fibers, but their material properties are highly variable; for example, strength and toughness vary more than fourfold among the 21 species we investigated. Furthermore, associations between different properties are complex. Some traits, such as strength and extensibility, seem to evolve independently and show no evidence of correlation or trade-off across species, even though trade-offs between these properties are observed within species. Material properties retain different levels of phylogenetic signal, suggesting that traits such as extensibility and toughness may be subject to different types or intensities of selection in several spider lineages. The picture that emerges is complex, with a mosaic pattern of trait evolution producing a diverse set of materials across spider species. These results show that the properties of biological materials are the target of selection, and that these changes can produce evolutionarily and ecologically important diversity.

  3. 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.

  4. Spider phobics more easily see a spider in morphed schematic pictures

    PubMed Central

    Kolassa, Iris-Tatjana; Buchmann, Arlette; Lauche, Romy; Kolassa, Stephan; Partchev, Ivailo; Miltner, Wolfgang HR; Musial, Frauke

    2007-01-01

    Background Individuals with social phobia are more likely to misinterpret ambiguous social situations as more threatening, i.e. they show an interpretive bias. This study investigated whether such a bias also exists in specific phobia. Methods Individuals with spider phobia or social phobia, spider aficionados and non-phobic controls saw morphed stimuli that gradually transformed from a schematic picture of a flower into a schematic picture of a spider by shifting the outlines of the petals until they turned into spider legs. Participants' task was to decide whether each stimulus was more similar to a spider, a flower or to neither object while EEG was recorded. Results An interpretive bias was found in spider phobia on a behavioral level: with the first opening of the petals of the flower anchor, spider phobics rated the stimuli as more unpleasant and arousing than the control groups and showed an elevated latent trait to classify a stimulus as a spider and a response-time advantage for spider-like stimuli. No cortical correlates on the level of ERPs of this interpretive bias could be identified. However, consistent with previous studies, social and spider phobic persons exhibited generally enhanced visual P1 amplitudes indicative of hypervigilance in phobia. Conclusion Results suggest an interpretive bias and generalization of phobia-specific responses in specific phobia. Similar effects have been observed in other anxiety disorders, such as social phobia and posttraumatic stress disorder. PMID:18021433

  5. '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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Molecular studies of a novel dragline silk from a nursery web spider, Euprosthenops sp. (Pisauridae).

    PubMed

    Pouchkina-Stantcheva, Natalia N; McQueen-Mason, Simon J

    2004-08-01

    Various spider species produce dragline silks with different mechanical properties. The primary structure of silk proteins is thought to contribute to the elasticity and strength of the fibres. Previously published work has demonstrated that the dragline silk of Euprosthenops sp. is stiffer then comparable silk of Nephila edulis, Araneus diadematus and Latrodectus mactans. Our studies of Euprosthenops dragline silk at the molecular level have revealed that nursery web spider fibroin has the highest polyalanine content among previously characterised silks and this is likely to contribute to the superior qualities of pisaurid dragline.

  11. Molecular architecture and evolution of a modular spider silk protein gene.

    PubMed

    Hayashi, C Y; Lewis, R V

    2000-02-25

    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.

  12. 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.

  13. 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.

  14. 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

  15. Draft Genome Sequences of Six Novel Picorna-Like Viruses from Washington State Spiders

    PubMed Central

    Shean, Ryan C.; Makhsous, Negar; Crawford, Rodney L.; Jerome, Keith R.

    2017-01-01

    ABSTRACT We report draft genome sequences of six novel Picornavirales members from six different spider species found in Washington state. These six viral sequences distinctly clustered together phylogenetically with less than 35% amino acid identity to the closest reference viral genome. PMID:28254976

  16. 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...

  17. Density mediates grasshopper performance in response to temperature manipulation and spider predation in tallgrass prairie.

    PubMed

    Laws, A N; Joern, A

    2017-04-01

    Species interactions are often context-dependent, where outcomes require an understanding of influences among multiple biotic and abiotic factors. However, it remains unclear how abiotic factors such as temperature combine with important biotic factors such as density-dependent food limitation and predation to influence species interactions. Using a native grassland - grasshopper - wolf spider model food chain in tallgrass prairie, we conducted a manipulative field experiment to examine how predator-prey interactions respond to manipulations of temperature, grasshopper density, and food chain length. We find that grasshopper performance responses to temperature and predator treatments were density dependent. At high densities, grasshopper survival decreased with increased temperature when no spiders were present. When spiders were present, grasshopper survival was reduced, and this effect was strongest in the cooled treatment. In contrast, grasshopper survival did not vary significantly with spider presence or among temperature treatments at low grasshopper densities. Our results indicate that context-dependent species interactions are common and highlight the importance of understanding how and when key biotic and abiotic factors combine to influence species interactions.

  18. The multiple disguises of spiders: web colour and decorations, body colour and movement.

    PubMed

    Théry, Marc; Casas, Jérôme

    2009-02-27

    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.

  19. 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.

  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. Spider silk gut: Development and characterization of a novel strong spider silk fiber

    NASA Astrophysics Data System (ADS)

    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

    2014-12-01

    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.

  2. Spider silk gut: development and characterization of a novel strong spider silk fiber.

    PubMed

    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

    2014-12-05

    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.

  3. 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

  4. 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.

  5. [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

    2005-11-06

    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.

  6. 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.

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. Peptidomic and transcriptomic profiling of four distinct spider venoms.

    PubMed

    Oldrati, Vera; Koua, Dominique; Allard, Pierre-Marie; Hulo, Nicolas; Arrell, Miriam; Nentwig, Wolfgang; Lisacek, Frédérique; Wolfender, Jean-Luc; Kuhn-Nentwig, Lucia; Stöcklin, Reto

    2017-01-01

    Venom based research is exploited to find novel candidates for the development of innovative pharmacological tools, drug candidates and new ingredients for cosmetic and agrochemical industries. Moreover, venomics, as a well-established approach in systems biology, helps to elucidate the genetic mechanisms of the production of such a great molecular biodiversity. Today the advances made in the proteomics, transcriptomics and bioinformatics fields, favor venomics, allowing the in depth study of complex matrices and the elucidation even of minor compounds present in minute biological samples. The present study illustrates a rapid and efficient method developed for the elucidation of venom composition based on NextGen mRNA sequencing of venom glands and LC-MS/MS venom proteome profiling. The analysis of the comprehensive data obtained was focused on cysteine rich peptide toxins from four spider species originating from phylogenetically distant families for comparison purposes. The studied species were Heteropoda davidbowie (Sparassidae), Poecilotheria formosa (Theraphosidae), Viridasius fasciatus (Viridasiidae) and Latrodectus mactans (Theridiidae). This led to a high resolution profiling of 284 characterized cysteine rich peptides, 111 of which belong to the Inhibitor Cysteine Knot (ICK) structural motif. The analysis of H. davidbowie venom revealed a high richness in term of venom diversity: 95 peptide sequences were identified; out of these, 32 peptides presented the ICK structural motif and could be classified in six distinct families. The profiling of P. formosa venom highlighted the presence of 126 peptide sequences, with 52 ICK toxins belonging to three structural distinct families. V. fasciatus venom was shown to contain 49 peptide sequences, out of which 22 presented the ICK structural motif and were attributed to five families. The venom of L. mactans, until now studied for its large neurotoxins (Latrotoxins), revealed the presence of 14 cysteine rich

  12. An approach to spider bites. Erroneous attribution of dermonecrotic lesions to brown recluse or hobo spider bites in Canada.

    PubMed Central

    Bennett, Robert G.; Vetter, Richard S.

    2004-01-01

    OBJECTIVE: To dispel prevalent myths surrounding diagnosis of dermonecrotic and associated conditions supposedly resulting from bites of brown recluse, hobo, or other spiders in Canada. SOURCES OF INFORMATION: Worldwide, spider bites are regularly misdiagnosed as the etiologic agents in human dermonecrosis mainly as a result of inaccurate, erroneous, or hyperbolic popular and professional literature based on inference, circumstantial evidence, inferior clinical trials, and misunderstanding of the facts regarding spider-bite envenomation. MAIN MESSAGE: A working diagnosis of "spider bite" or publishing a case history should be considered only when a spider is caught in the act of biting or otherwise reliably associated with a lesion. Accurate identification of the spider could be critical for correct diagnosis and subsequent treatment. CONCLUSION: Brown recluse spiders are not found in Canada. Hobo spiders have not been reliably implicated in dermonecrosis. Worldwide, spider-bite envenomation is an unlikely cause of dermonecrosis. Canadian physicians should give priority consideration to other, more likely, causes. PMID:15455808

  13. 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.

  14. Ecology of a bolas spider, Mastophora hutchinsoni: phenology, hunting tactics, and evidence for aggressive chemical mimicry.

    PubMed

    Yeargan, Kenneth V

    1988-01-01

    Bolas spiders are relatively rare members of the large family known as orb weavers. Instead of using a typical web to capture prey, late-stadia and adult female bolas spiders swing a droplet of adhesive on a thread at flying insects. Mastophora hutchinsoni (Araneae: Araneidae) is one of five Mastophora species known from the United States and occurs over much of eastern North America. It is univoltine in Kentucky and overwinters in the egg stage. Spiderling emerged in May, the diminutive males matured in late June and early July, and females matured in early September. Eggs were produced from late September to late October or early November. This report is the first complete documentation of the population phenology of any bolas spider. Newly-emerged M. hutchinsoni spiderlings did not use a bolas, but instead hunted by positioning themselves on the underside of leaf margins where they ambushed small arthropods that crawled along the leaf margins. Subadult and adult female M. hutchinsoni used a bolas to capture moths. Only male moths were captured, specifically three species of Noctuidae (bristly cutworm, bronzed cutworm, and smoky tetanolita) and one species of Pyralidae (bluegrass webworm). Among 492 prey captured by more than twenty spiders at two sites during 1985 and 1986, smoky tetanolita moths and bristly cutworm moths accounted for 93% of the total. The flight behavior of approaching moths, the limited taxa caught from a large available moth fauna, and the fact that only males were caught support the hypothesis that the spider attracts its prey by producing chemicals which mimic the sex pheromones of these moth species. Adult female M. hutchinsoni frequently captured more than one moth species on a given night. The two most common prey species were active at different times of night, the bristly cutworm soon after nightfall and the smoky tetanolita generally between 11:00 p.m. and dawn. This pattern suggests that mating activity of these moth species may be

  15. Venom of the Brazilian Spider Sicarius ornatus (Araneae, Sicariidae) Contains Active Sphingomyelinase D: Potential for Toxicity after Envenomation

    PubMed Central

    Lopes, Priscila Hess; Bertani, Rogério; Gonçalves-de-Andrade, Rute M.; Nagahama, Roberto H.; van den Berg, Carmen W.; Tambourgi, Denise V.

    2013-01-01

    Background The spider family Sicariidae includes two genera, Sicarius and Loxosceles. Bites by Sicarius are uncommon in humans and, in Brazil, a single report is known of a 17-year old man bitten by a Sicarius species that developed a necrotic lesion similar to that caused by Loxosceles. Envenomation by Loxosceles spiders can result in dermonecrosis and severe ulceration. Sicarius and Loxosceles spider venoms share a common characteristic, i.e., the presence of Sphingomyelinases D (SMase D). We have previously shown that Loxosceles SMase D is the enzyme responsible for the main pathological effects of the venom. Recently, it was demonstrated that Sicarius species from Africa, like Loxosceles spiders from the Americas, present high venom SMase D activity. However, despite the presence of SMase D like proteins in venoms of several New World Sicarius species, they had reduced or no detectable SMase D activity. In order to contribute to a better understanding about the toxicity of New World Sicarius venoms, the aim of this study was to characterize the toxic properties of male and female venoms from the Brazilian Sicarius ornatus spider and compare these with venoms from Loxosceles species of medical importance in Brazil. Methodology/Principal Findings SDS-PAGE analysis showed variations in the composition of Loxosceles spp. and Sicarius ornatus venoms. Differences in the electrophoretic profiles of male and female venoms were also observed, indicating a possible intraspecific variation in the composition of the venom of Sicarius spider. The major component in all tested venoms had a Mr of 32–35 kDa, which was recognized by antiserum raised against Loxosceles SMases D. Moreover, male and female Sicarius ornatus spiders' venoms were able to hydrolyze sphingomyelin, thus showing an enzymatic activity similar to that determined for Loxosceles venoms. Sicarius ornatus venoms, as well as Loxosceles venoms, were able to render erythrocytes susceptible to lysis by

  16. The Occurrence of Red-Back Spider Latrodectus hasselti (Araneae: Theridiidae) in Bandar Abbas, Southern Part of Iran

    PubMed Central

    Shahi, M; Hosseini, A; Shemshad, K; Rafinejad, J

    2011-01-01

    Background: Due to importance and fatal affect of Red-back spiders, Latrodectus hasselti, a faunistic survey for presence of this spider in Bandar Abbas has been conducted. This animal is considerably the most medically importance spiders all over the world. Methods: Live adult spider specimens were collected from Bandar Abbas town using hand catch conventional method and transferred to the laboratory throughout the summer of 2008. They were identified based on morphological characteristics and taxonomic keys and confirmed by some external experts. Results: Results showed the occurrence of the red-back spider, L. hasselti from Bandar Abbas, southern port of Iran. Two female specimens were found. The spider had specific morphological characters including black color with an obvious orange to red longitudinal strip on its upper parts of abdomen. Conclusion: Although the specimens were collected from south of the country, however since the region is an important harbor and port and goods come form different parts of world we assume the possibility of arrival from its origin and native breeding sites of the world. Therefore further investigation is needed to clarify the presence of this species in different parts of Iran. PMID:22808411

  17. 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.

  18. 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

  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.

  20. 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

  1. 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

  2. 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.

  3. First-passage properties of molecular spiders

    NASA Astrophysics Data System (ADS)

    Semenov, Oleg; Mohr, David; Stefanovic, Darko

    2013-07-01

    Molecular spiders are synthetic catalytic DNA-based nanoscale walkers. We study the mean first-passage time for abstract models of spiders moving on a finite two-dimensional lattice with various boundary conditions and compare it with the mean first-passage time of spiders moving on a one-dimensional track. We evaluate by how much the slowdown on newly visited sites, owing to catalysis, can improve the mean first-passage time of spiders and show that in one dimension, when both ends of the track are an absorbing boundary, the performance gain is lower than in two dimensions, when the absorbing boundary is a circle; this persists even when the absorbing boundary is a single site.

  4. Goblin spiders without distinct receptacula seminis (Arachnida: Araneae: Oonopidae).

    PubMed

    Burger, Matthias

    2010-09-01

    The mechanism of sperm transfer in spiders is unique among arthropods. Males use their modified pedipalps to transmit sperm which is received by females of most spider groups in specialized organs, the receptacula seminis. Oonopidae are a diverse spider family belonging to the Haplogynae. Female haplogynes have supposedly simple genitalia where the receptacula derive from the uterus externus, which is the duct passed by the eggs. The purpose of the present study is to describe the unusual female genitalia of the oonopids Xyphinus sp. and Ischnothyreus sp. by combining three methods of investigation: histological serial sections, scanning electron microscopy, and X-ray ultra microscopy, and to compare the results with previous findings on haplogynes. Furthermore, the male palps are briefly described. The female genitalia of both investigated species do not correspond to the general description of haplogyne genitalia given in the literature. Distinct receptacula are lacking in both species. In Xyphinus sp., sperm are deposited into the uterus internus. A sclerite with attached muscles in the uterus wall might serve females to lock the uterus during copulation in order to prevent sperm from getting into it. The male palp of Xyphinus sp. bears complicated structures indicating that males could use the palps as copulatory courtship devices. The ventral scutum of female Ischnothyreus sp. forms a large depression which was always empty in the examined specimens. Sperm could be stored in a large fold of the uterus externus. As in Xyphinus sp., spermatozoa inside the uterus internus of Ischnothyreus sp. indicate that fertilization takes place in the uterus or the ovary. The function of a sclerotized squiggled tube in females of Ischnothyreus sp. remains unknown. Surrounding glandular tissue suggests the involvement of the tube in glandular activity. The male palp shows a simple embolus accompanied by a small conductor.

  5. Spider's web inspires fibres for industry

    NASA Astrophysics Data System (ADS)

    Dacey, James

    2010-03-01

    Spiders may not be everybody's idea of natural beauty, but nobody can deny the artistry in the webs that they spin, especially when decorated with water baubles in the morning dew. Inspired by this spectacle, a group of researchers in China has mimicked the structural properties of the spider's web to create a fibre for industry that can manipulate water with the same skill and efficiency, writes James Dacey.

  6. 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

  7. Designing Spider Silk Proteins for Materials Applications

    DTIC Science & Technology

    2009-10-28

    spider silk. Accomplishments: YEAR 1. Bacteria were genetically engineered to produce two spider silk protein variants composed of basic repeat...silk proteins. In another development with Nexia we have purchased most of the founder goats they produced in order to protect the genetics they...Nexia produced in order to protect the genetics they developed. After a 9 month odyssey of bureaucratic hassles we will brought the goats into othe

  8. Recombinant DNA production of spider silk proteins.

    PubMed

    Tokareva, Olena; Michalczechen-Lacerda, Valquíria A; Rech, Elíbio L; Kaplan, David L

    2013-11-01

    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.

  9. A new jumping spider of the genus Stenaelurillus Simon, 1886 from India (Araneae: Salticidae: Aelurillina).

    PubMed

    Caleb, John T D; Mathai, Manu Thomas

    2016-04-12

    The genus Stenaelurillus Simon, 1886 is known from 35 species worldwide, including 27 species from Africa and eight from Asia (four species known from India, one from Iran, one from China, one from Tibet and one from Vietnam) (World Spider Catalog 2016). The four species known from India are S. albus Sebastian et al., 2015, S. jagannathae Das, Malik & Vidhel, 2015, S. lesserti Reimoser, 1934 and S. sarojinae Caleb & Mathai, 2014 (Prószyński 2015; World Spider Catalog 2016). The present paper contains description of Stenaelurillus metallicus sp. nov., discovered from scrub jungle remnants of tropical dry evergreen forests, a unique habitat found in Madras Christian College campus, Chennai, Tamil Nadu, India.

  10. 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 with 40% ethanol (ETOH) in order to determine the effects of alcohol on the web-spinning ability of orb weaver spiders. It was hypothesized that alcohol would have a deleterious effect on the number of radii, number of cells, and area of cells in the webs of orb weaving…

  11. Bartonella henselae infection in a family experiencing neurological and neurocognitive abnormalities after woodlouse hunter spider bites

    PubMed Central

    2013-01-01

    Background Bartonella species comprise a group of zoonotic pathogens that are usually acquired by vector transmission or by animal bites or scratches. Methods PCR targeting the Bartonella 16S-23S intergenic spacer (ITS) region was used in conjunction with BAPGM (Bartonella alpha Proteobacteria growth medium) enrichment blood culture to determine the infection status of the family members and to amplify DNA from spiders and woodlice. Antibody titers to B. vinsonii subsp. berkhoffii (Bvb) genotypes I-III, B. henselae (Bh) and B. koehlerae (Bk) were determined using an IFA test. Management of the medical problems reported by these patients was provided by their respective physicians. Results In this investigation, immediately prior to the onset of symptoms two children in a family experienced puncture-like skin lesions after exposure to and presumptive bites from woodlouse hunter spiders. Shortly thereafter, the mother and both children developed hive-like lesions. Over the ensuing months, the youngest son was diagnosed with Guillain-Barre (GBS) syndrome followed by Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP). The older son developed intermittent disorientation and irritability, and the mother experienced fatigue, headaches, joint pain and memory loss. When tested approximately three years after the woodlouse hunter spider infestation, all three family members were Bartonella henselae seroreactive and B. henselae DNA was amplified and sequenced from blood, serum or Bartonella alpha-proteobacteria (BAPGM) enrichment blood cultures from the mother and oldest son. Also, B. henselae DNA was PCR amplified and sequenced from a woodlouse and from woodlouse hunter spiders collected adjacent to the family’s home. Conclusions Although it was not possible to determine whether the family’s B. henselae infections were acquired by spider bites or whether the spiders and woodlice were merely accidental hosts, physicians should consider the possibility that B

  12. Amino acid sequence of versutoxin, a lethal neurotoxin from the venom of the funnel-web spider Atrax versutus.

    PubMed

    Brown, M R; Sheumack, D D; Tyler, M I; Howden, M E

    1988-03-01

    The complete amino acid sequence of versutoxin, a lethal neurotoxic polypeptide isolated from the venom of male and female funnel-web spiders of the species Atrax versutus, was determined. Sequencing was performed in a gas-phase protein sequencer by automated Edman degradation of the S-carboxymethylated toxin and fragments of it produced by reaction with CNBr. Versutoxin consisted of a single chain of 42 amino acid residues. It was found to have a high proportion of basic residues and of cystine. The primary structure showed marked homology with that of robustoxin, a novel neurotoxin recently isolated from the venom of another funnel-web-spider species, Atrax robustus.

  13. Amino acid sequence of versutoxin, a lethal neurotoxin from the venom of the funnel-web spider Atrax versutus.

    PubMed Central

    Brown, M R; Sheumack, D D; Tyler, M I; Howden, M E

    1988-01-01

    The complete amino acid sequence of versutoxin, a lethal neurotoxic polypeptide isolated from the venom of male and female funnel-web spiders of the species Atrax versutus, was determined. Sequencing was performed in a gas-phase protein sequencer by automated Edman degradation of the S-carboxymethylated toxin and fragments of it produced by reaction with CNBr. Versutoxin consisted of a single chain of 42 amino acid residues. It was found to have a high proportion of basic residues and of cystine. The primary structure showed marked homology with that of robustoxin, a novel neurotoxin recently isolated from the venom of another funnel-web-spider species, Atrax robustus. PMID:3355530

  14. New records of spider wasps (Hymenoptera, Pompilidae) from Colombia

    PubMed Central

    Castro-Huertas, Valentina; Pitts, James P.; Rodriguez, Juanita; Cecilia Waichert; Fernández, Fernando

    2014-01-01

    Abstract New records of genera and species of spider wasps (Hymenoptera: Pompilidae) from Colombia are provided. Agenioideus, Cryptocheilus, Evagetes, Mystacagenia, and Xerochares are newly recorded genera from Colombia. Nineteen species are first recorded from Colombia: Aimatocare vitrea (Fox); Ageniella azteca (Cameron); Ageniella curtipinus (Cameron); Ageniella fallax (Arlé); Ageniella hirsuta Banks; Ageniella pilifrons (Cameron); Ageniella pretiosa Banks; Ageniella sanguinolenta (Smith); Ageniella zeteki (Banks); Agenioideus birkmanni (Banks); Aporus (Aporus) cuzco Evans; Aporus (Cosmiaporus) diverticulus (Fox); Aporus (Notoplaniceps) canescens Smith; Euplaniceps exilis (Banks); Euplaniceps herbertii (Fox); Irenangelus clarus Evans; Mystacagenia bellula Evans; Phanochilus nobilitatus (Smith) and Xerochares expulsus Schulz. The following species and genera have their occurence ranges expanded for South America: Ageniella azteca (Cameron); Ageniella zeteki (Banks); Agenioideus birkmanni (Banks); and Xerochares expulsus Schulz; Cryptocheilus Panzer; and Xerochares Evans. PMID:25349495

  15. A 4-year study of invasive and native spider populations in Maine

    USGS Publications Warehouse

    Jakob, Elizabeth M.; Porter, Adam H.; Ginsberg, Howard; Bednarski, Julie V.; Houser, Jeremy

    2011-01-01

    Invasive spiders pose potential threats to native spiders. In 2002, the European spider Linyphia triangularis (Clerck, 1757) (Araneae: Linyphiidae) was discovered in all but one county in Maine. At Acadia National Park, we conducted a 4-year study of L. triangularis and three native linyphiid species of a similar size (Frontinella communis (Hentz, 1850), Pityohyphantes subarcticus Chamberlin and Ivie, 1943, and Neriene radiata (Walckenaer, 1842)). Using line-transect surveys, we measured population densities in coastal and forest habitat. The density of L. triangularis varied across years but was always significantly higher on the coast than in the forest. In contrast, only one native species was present on the coast and at very low numbers. Coastal L. triangularis were larger and in better condition than those in the forest, and numbers and biomass of insect prey were also higher on the coast. In 2 years, we also conducted transects at a second coastal location in Maine where the invader was at low density. At that site, native densities were substantially higher than at either Acadia site. Our data are consistent with the hypothesis that L. triangularis is reducing populations of native spiders. Companion studies suggest that L. triangularis negatively impacts natives by usurping both web sites and webs.

  16. Crypsis via leg clustering: twig masquerading in a spider.

    PubMed

    Zhang, Shichang; Mao, Kuei-Kai; Lin, Po-Ting; Ho, Chiu-Ju; Hung, Wei; Piorkowski, Dakota; Liao, Chen-Pan; Tso, I-Min

    2015-03-01

    The role of background matching in camouflage has been extensively studied. However, contour modification has received far less attention, especially in twig-mimicking species. Here, we studied this deceptive strategy by revealing a special masquerade tactic, in which the animals protract and cluster their legs linearly in the same axis with their bodies when resting, using the spider Ariamnes cylindrogaster as a model. We used cardboard papers to construct dummies resembling spiders in appearance and colour. To differentiate the most important factors in the concealment effect, we manipulated body size (long or short abdomen) and resting postures (leg clustered or spread) of the dummies and recorded the responses of predators to different dummy types in the field. The results showed that dummies with clustered legs received significantly less attention from predators, regardless of the body length. Thus, we conclude that A. cylindrogaster relies on the resting posture rather than body size for predator avoidance. This study provides, to the best of our knowledge, empirical evidence for the first time that twig-mimicking species can achieve effective camouflage by contour modification.

  17. A Parasitoid Wasp Induces Overwintering Behaviour in Its Spider Host

    PubMed Central

    Korenko, Stanislav; Pekár, Stano

    2011-01-01

    Parasites and parasitoids control behaviors of their hosts. However, the origin of the behavior evoked by the parasitic organism has been rarely identified. It is also not known whether the manipulation is universal or host-specific. Polysphinctine wasps, koinobiont ectoparasitoids of several spider species that manipulate host web-spinning activity for their own protection during pupation, provide an ideal system to reveal the origin of the evoked behavior. Larva of Zatypota percontatoria performed species-specific manipulation of theridiid spiders, Neottiura bimaculata and Theridion varians, shortly before pupation. Parasitized N. bimaculata produced a dense web, whereas parasitized T. varians built a cupola-like structure. The larva pupated inside of either the dense web or the cupola-like structure. We discovered that unparasitized N. bimaculata produce an analogous dense web around their eggsacs and for themselves during winter, while T. varians construct an analogous ‘cupola’ only for overwintering. We induced analogous manipulation in unparasitized hosts by altering ambient conditions. We discovered that the behavior evoked by larvae in two hosts was functionally similar. The larva evoked protective behaviors that occur in unparasitized hosts only during specific life-history periods. PMID:21931784

  18. Benefits of cooperation with genetic kin in a subsocial spider.

    PubMed

    Schneider, J M; Bilde, T

    2008-08-05

    Interaction within groups exploiting a common resource may be prone to cheating by selfish actions that result in disadvantages for all members of the group, including the selfish individuals. Kin selection is one mechanism by which such dilemmas can be resolved. This is because selfish acts toward relatives include the cost of lowering indirect fitness benefits that could otherwise be achieved through the propagation of shared genes. Kin selection theory has been proved to be of general importance for the origin of cooperative behaviors, but other driving forces, such as direct fitness benefits, can also promote helping behavior in many cooperatively breeding taxa. Investigating transitional systems is therefore particularly suitable for understanding the influence of kin selection on the initial spread of cooperative behaviors. Here we investigated the role of kinship in cooperative feeding. We used a cross-fostering design to control for genetic relatedness and group membership. Our study animal was the periodic social spider Stegodyphus lineatus, a transitional species that belongs to a genus containing both permanent social and periodic social species. In S. lineatus, the young cooperate in prey capture and feed communally. We provide clear experimental evidence for net benefits of cooperating with kin. Genetic relatedness within groups and not association with familiar individuals directly improved feeding efficiency and growth rates, demonstrating a positive effect of kin cooperation. Hence, in communally feeding spiders, nepotism favors group retention and reduces the conflict between selfish interests and the interests of the group.

  19. Crypsis via leg clustering: twig masquerading in a spider

    PubMed Central

    Zhang, Shichang; Mao, Kuei-Kai; Lin, Po-Ting; Ho, Chiu-Ju; Hung, Wei; Piorkowski, Dakota; Liao, Chen-Pan; Tso, I-Min

    2015-01-01

    The role of background matching in camouflage has been extensively studied. However, contour modification has received far less attention, especially in twig-mimicking species. Here, we studied this deceptive strategy by revealing a special masquerade tactic, in which the animals protract and cluster their legs linearly in the same axis with their bodies when resting, using the spider Ariamnes cylindrogaster as a model. We used cardboard papers to construct dummies resembling spiders in appearance and colour. To differentiate the most important factors in the concealment effect, we manipulated body size (long or short abdomen) and resting postures (leg clustered or spread) of the dummies and recorded the responses of predators to different dummy types in the field. The results showed that dummies with clustered legs received significantly less attention from predators, regardless of the body length. Thus, we conclude that A. cylindrogaster relies on the resting posture rather than body size for predator avoidance. This study provides, to the best of our knowledge, empirical evidence for the first time that twig-mimicking species can achieve effective camouflage by contour modification. PMID:26064622

  20. Towards a DNA Barcode Reference Database for Spiders and Harvestmen of Germany

    PubMed Central

    Astrin, Jonas J.; Höfer, Hubert; Spelda, Jörg; Holstein, Joachim; Bayer, Steffen; Hendrich, Lars; Huber, Bernhard A.; Kielhorn, Karl-Hinrich; Krammer, Hans-Joachim; Lemke, Martin; Monje, Juan Carlos; Morinière, Jérôme; Rulik, Björn; Petersen, Malte; Janssen, Hannah; Muster, Christoph

    2016-01-01

    As part of the German Barcode of Life campaign, over 3500 arachnid specimens have been collected and analyzed: ca. 3300 Araneae and 200 Opiliones, belonging to almost 600 species (median: 4 individuals/species). This covers about 60% of the spider fauna and more than 70% of the harvestmen fauna recorded for Germany. The overwhelming majority of species could be readily identified through DNA barcoding: median distances between closest species lay around 9% in spiders and 13% in harvestmen, while in 95% of the cases, intraspecific distances were below 2.5% and 8% respectively, with intraspecific medians at 0.3% and 0.2%. However, almost 20 spider species, most notably in the family Lycosidae, could not be separated through DNA barcoding (although many of them present discrete morphological differences). Conspicuously high interspecific distances were found in even more cases, hinting at cryptic species in some instances. A new program is presented: DiStats calculates the statistics needed to meet DNA barcode release criteria. Furthermore, new generic COI primers useful for a wide range of taxa (also other than arachnids) are introduced. PMID:27681175

  1. Choice of hunting site as a consequence of experience in late-instar crab spiders.

    PubMed

    Morse, Douglass H

    1999-08-01

    Earlier experiences may play an important role in the choice of hunting sites, but their effects on the foraging repertoire of most animals remain poorly understood. I tested the role of previous flower choices (hunting sites) by penultimate-instar female crab spiders Misumena vatia in making subsequent patch-choice decisions. M. vatia is a sit-and-wait predator, and the two flower species used, ox-eye daisy Chrysanthemum leucanthemum and common buttercup Ranunculus acris, are important hunting sites. Spiders with different immediate experience showed similar short-term (<1 day) giving-up times on the two flower species, independent of their previous substrate. However, four-fifths of the individuals that remained a day or longer tended to leave buttercups sooner than daisies, especially if they had previously occupied daisies. Thus they may directly assess the quality of a potential hunting site, perhaps in response to prey abundance, but previous experience may play a minor role as well. Of spiders that made several consecutive choices of hunting sites, those on daisies often confined these runs to daisies (one of two years); those on buttercups did not exhibit comparable fidelity. Spiders molting into the adult stage almost always subsequently chose the same flower species (either daisy or buttercup) as the one on which they molted. Thus, juvenile experiences may influence adults, the critical stage when virtually all of the spiders' reproductive resources are gathered, even if this resulted from imprinting on their molt sites rather than carrying information over the molt.

  2. Envenomation by spiders of the genus Hololena (Araneae: Agelenidae).

    PubMed

    Vetter, Richard S

    2012-09-01

    Three verified bites from Hololena spiders (Family Agelenidae) are presented here. Two male victims, each over 100 kg weight (bitten by female spiders), experienced headaches and 4-h episodes of vomiting. A female bite victim (bitten by a male spider) experienced minor reaction. None sought medical attention; symptoms resolved in a few days. Although these incidents were not serious, reactions in the male victims were more dynamic than usual generic spider bites (minor edema, minor erythema).

  3. Four new species of the spider genus Nesticella Lehtinen & Saaristo, 1980 from Laos, Thailand and Myanmar and the first description of the male of Nesticella yui Wunderlich & Song, 1995 with a proposed new diagnostic character for the family Nesticidae Simon, 1894 (Arachnida, Araneae).

    PubMed

    Grall, Elena; Jäger, Peter

    2016-03-02

    During various expeditions to Laos between 2003 and 2012 and one expedition to Myanmar in 2014, spiders of the family Nesticidae were collected inside and outside of caves. This was the first time this family was encountered in Laos. All specimens belong to the genus Nesticella Lehtinen & Saaristo, 1980. Four species have been recognized as being new to science, which are described in this paper: Nesticella beccus n. sp. (male, female; LAOS: Bolikhamsay Province, Luang Prabang Province, Huaphan Province, Khammouan Province, THAILAND: Mae Hong Son Province), Nesticella laotica n. sp. (male, female; LAOS: Vientiane Province, Huaphan Province, Luang Prabang Province, Bolikhamsay Province), Nesticella foelixi n. sp. (male; LAOS: Bolikhamsay Province) and Nesticella michaliki n. sp. (male, female; MYANMAR: Chin State). The male of Nesticella yui Wunderlich & Song, 1995 is described for the first time and it is the first record for Laos. Results from a first micro-computed tomography analysis of a female copulatory organ for this genus are provided. This analysis proves that female Nesticella exhibit a complex functional receptaculum, which is highly complex within the genus. The presence of a special type of leg setae (pipette setae) in males is proposed as diagnostic for the family Nesticidae.

  4. Jewelled spider flies of North America: a revision and phylogeny of Eulonchus Gerstaecker (Diptera, Acroceridae)

    PubMed Central

    Borkent, Christopher J.; Gillung, Jessica P.; Winterton, Shaun L.

    2016-01-01

    Abstract The spider fly genus Eulonchus Gerstaecker is found throughout the Nearctic Region. Six species are recognized and intraspecific morphological variation is documented in several species. A phylogeny of Eulonchus based on DNA sequence data of three molecular markers (COI, CAD, and 16S) is presented and relationships of species are discussed in the light of biogeography and host usage. All six species of Eulonchus are redescribed using natural language descriptions exported from a character matrix, and a key to species is presented. Lectotypes are designated for Eulonchus sapphirinus Osten Sacken, Eulonchus smaragdinus Gerstaecker, and Eulonchus tristis Loew. PMID:27829790

  5. Spider diffraction: a comparison of curved and straight legs

    SciTech Connect

    Richter, J.L.

    1984-06-15

    It has been known for some time that, if curved legs rather than the usual straight ones are used in the spider that supports the secondary optics in certain telescopes, the visible diffraction effect is reduced. Fraunhofer theory is used to calculate the diffraction effects due to the curved leg spider. Calculated and photographic diffraction patterns are compared for straight and curved leg spiders.

  6. Nectar feeding by wandering spiders on cotton plants.

    PubMed

    Taylor, R M; Pfannenstiel, R S

    2008-08-01

    Spiders are assumed to be strictly carnivorous in assessments of their nutritional and energetic requirements, their habitat preferences, and their potential as biological control agents. However, members of Salticidae (jumping spiders), Thomisidae (crab spiders), and the fast-moving Miturgidae, Anyphaenidae, and Corinnidae, all non-webbuilding wandering spiders, have been observed at floral and extrafloral nectaries of plants, presumably feeding on nectar. To test spiders in the field for nectar feeding, we used a cold anthrone test to detect the presence of ingested fructose, a plant-derived sugar, in wandering spiders occupying cotton plants (Gossypium hirsutum L.), which have floral and extrafloral nectaries. Field collections focused on three ecologically similar, highly active nocturnal spiders: Cheiracanthium inclusum (Hentz) (Miturgidae), Hibana futilis (Banks), and H. arunda (Platnick) (Anyphaenidae). During 2002 and 2003, 27 and 21%, respectively, of all field-collected adults and subadults tested positive for fructose, indicating consumption of extrafloral nectar. In both years, significantly more females were positive than males (38 versus 11% in 2002; 26 versus 12% in 2003). Immatures tested positive at a lower rate than adults (3 and 13%, respectively). Smaller numbers of spiders in the Lycosidae, Oxyopidae, and Thomisidae were also tested. Among the thomisids, 38% in 2002 and 41% in 2003 tested positive for fructose. None of the lycosids (wolf spiders) tested positive; two of nine oxyopids (lynx spiders) did test positive. Oxyopidae is new to the list of nectarivorous spiders. These results suggest that nectarivory is common for foliage wandering spiders and may contribute to fitness.

  7. Mass predicts web asymmetry in Nephila spiders

    NASA Astrophysics Data System (ADS)

    Kuntner, Matjaž; Gregorič, Matjaž; Li, Daiqin

    2010-12-01

    The architecture of vertical aerial orb webs may be affected by spider size and gravity or by the available web space, in addition to phylogenetic and/or developmental factors. Vertical orb web asymmetry measured by hub displacement has been shown to increase in bigger and heavier spiders; however, previous studies have mostly focused on adult and subadult spiders or on several size classes with measured size parameters but no mass. Both estimations are suboptimal because (1) adult orb web spiders may not invest heavily in optimal web construction, whereas juveniles do; (2) size class/developmental stage is difficult to estimate in the field and is thus subjective, and (3) mass scales differently to size and is therefore more important in predicting aerial foraging success due to gravity. We studied vertical web asymmetry in a giant orb web spider, Nephila pilipes, across a wide range of size classes/developmental stages and tested the hypothesis that vertical web asymmetry (measured as hub displacement) is affected by gravity. On a sample of 100 webs, we found that hubs were more displaced in heavier and larger juveniles and that spider mass explained vertical web asymmetry better than other measures of spider size (carapace and leg lengths, developmental stage). Quantifying web shape via the ladder index suggested that, unlike in other nephilid taxa, growing Nephila orbs do not become vertically elongated. We conclude that the ontogenetic pattern of progressive vertical web asymmetry in Nephila can be explained by optimal foraging due to gravity, to which the opposing selective force may be high web-building costs in the lower orb. Recent literature finds little support for alternative explanations of ontogenetic orb web allometry such as the size limitation hypothesis and the biogenetic law.

  8. Mass predicts web asymmetry in Nephila spiders.

    PubMed

    Kuntner, Matjaz; Gregoric, Matjaz; Li, Daiqin

    2010-12-01

    The architecture of vertical aerial orb webs may be affected by spider size and gravity or by the available web space, in addition to phylogenetic and/or developmental factors. Vertical orb web asymmetry measured by hub displacement has been shown to increase in bigger and heavier spiders; however, previous studies have mostly focused on adult and subadult spiders or on several size classes with measured size parameters but no mass. Both estimations are suboptimal because (1) adult orb web spiders may not invest heavily in optimal web construction, whereas juveniles do; (2) size class/developmental stage is difficult to estimate in the field and is thus subjective, and (3) mass scales differently to size and is therefore more important in predicting aerial foraging success due to gravity. We studied vertical web asymmetry in a giant orb web spider, Nephila pilipes, across a wide range of size classes/developmental stages and tested the hypothesis that vertical web asymmetry (measured as hub displacement) is affected by gravity. On a sample of 100 webs, we found that hubs were more displaced in heavier and larger juveniles and that spider mass explained vertical web asymmetry better than other measures of spider size (carapace and leg lengths, developmental stage). Quantifying web shape via the ladder index suggested that, unlike in other nephilid taxa, growing Nephila orbs do not become vertically elongated. We conclude that the ontogenetic pattern of progressive vertical web asymmetry in Nephila can be explained by optimal foraging due to gravity, to which the opposing selective force may be high web-building costs in the lower orb. Recent literature finds little support for alternative explanations of ontogenetic orb web allometry such as the size limitation hypothesis and the biogenetic law.

  9. A spider population in flux: selection and abandonment of artificial web-sites and the importance of intraspecific interactions in Lephthyphantes tenuis (Araneae: Linyphiidae) in wheat.

    PubMed

    Samu, Ferenc; Sunderland, Keith D; Topping, Chris J; Fenlon, John S

    1996-04-01

    Lepthyphantes tenuis, a small sheet-webbuilding linyphiid spider is one of the most abundant spider species of cereal fields in Europe. In the present study we examined the process of web-site selection and web-site tenacity by adult females of this species in a winter wheat field. Spiders were selective in their choice of web-site. Different immigration rates into various manipulated web-sites, in field and laboratory, suggested that structural support and suitable micro-climate (high humidity) are the most important factors in the selection. Small holes dug in the ground were the most favoured web-sites. Web-site occupation was influenced by the presence of other conspecific spiders. Territorial contests occurred between spiders attempting to occupy the same web, these almost invariably led to the take-over of the web when the intruder was heavier. Interference, but also a certain level of tolerance, between spiders within the same web-site but in different webs was suggested by direct and indirect evidence. Many holes supported two or even three spiders in vertically stratified webs. Leaving probability of marked spiders was significantly higher in multiply occupied holes than in holes with a single web. Comparison with the results of a no-interference stochastic model showed that multiple occupancy in nature is less frequent than predicted by the model. There was further evidence for weak extra-web-interference between spiders in that multiple occupancy was even less frequent and overall occupancy was lower in web-sites which were packed close to each other. However, a level of tolerance for crowding is shown by the fact that closely packed hole colonies supported a spider density 13 times higher than in natural web-sites in the field. A marking experiment was carried out to gain information on web-site tenacity (i.e. the length of time a spider spends in a web-site) and abandonment. The average duration of tenacity was less than 2 days. A random loss function

  10. Flee or fight: ontogenetic changes in the behavior of cobweb spiders in encounters with spider-hunting wasps.

    PubMed

    Uma, Divya B; Weiss, Martha R

    2012-12-01

    An animal's body size plays a predominant role in shaping its interspecific interactions, and, in encounters between two predators, often determines which shall be predator and which shall be prey. Spiders are top predators of insects, yet can fall prey to mud-dauber wasps that provision their larval nests with paralyzed spiders. Here we examined predator-prey interactions between Chalybion californicum (Saussure) (Sphecidae), a mud-dauber wasp, and Parasteatoda tepidariorum C. L. Koch (Theridiidae), a cobweb spider. We examined whether a spider's size influences its response to an attacking wasp, and report a size-dependent change in spider behavior: small-sized spiders fled, whereas medium- and large-sized spiders fought in response to wasp attacks. From the wasps' perspective, we examined whether spider size influences a wasp's hunting behavior and capture success. We found that wasps commonly approached small spiders, but were much less likely to approach medium and large spiders. However, wasp capture success did not vary with spider size. We also report a strategy used by Chalybion wasps toward cobweb spiders that is consistent with an interpretation of aggressive mimicry.

  11. Scale-dependent diversity patterns affect spider assemblages of two contrasting forest ecosystems

    NASA Astrophysics Data System (ADS)

    Schuldt, Andreas; Assmann, Thorsten; Schaefer, Matthias

    2013-05-01

    Spiders are important generalist predators in forests. However, differences in assemblage structure and diversity can have consequences for their functional impact. Such differences are particularly evident across latitudes, and their analysis can help to generate a better understanding of region-specific characteristics of predator assemblages. Here, we analyse the relationships between species richness, family richness and functional diversity (FD) as well as α- and β-components of epigeic spider diversity in semi-natural temperate and subtropical forest sites. As expected, within-plot and overall spider species and family richness were higher in the subtropical plots. In contrast, local FD within plots was similar between sites, and differences in FD only became evident at larger spatial scales due to higher species turnover in the subtropical forests. Our study indicates that the functional effects of predator assemblages can change across spatial scales. We discuss how differences in richness and functional diversity between contrasting forest ecosystems can depend on environmental heterogeneity and the effects of species filters acting at local scales. The high turnover observed in the species-rich subtropical forests also requires a more regional perspective for the conservation of the overall diversity and the ecological functions of predators than in less diverse forests, as strategies need to account for the large spatial heterogeneity among plots.

  12. Nonsynchronous recovery of community characteristics in island spiders after a catastrophic hurricane

    PubMed Central

    Schoener, Thomas W.; Spiller, David A.

    2006-01-01

    We monitored spiders on 41 Bahamian islands for 4 years before and then 4 years after the catastrophic Hurricane Floyd passed directly over the site, inundating the study islands with its storm surge. The respective recoveries of major community properties after this annihilation were far from synchronous. Before the hurricane, the species-area relation was generally strong and the slope showed no temporal trend. After the hurricane, the slope increased from near zero (7 months later) to a value about equal to its prehurricane state. The lizard effect (difference in spider abundance or species richness between islands with and without the lizard Anolis sagrei) was generally strong before the hurricane; 7 months after, the lizard effect on abundance was weak and the effect on richness had vanished. In subsequent years, the lizard effect on abundance became strong again, but the effect on species richness remained weak. The strength of the lizard effect on both abundance and richness over the 8 years was strongly positively related to the density of lizards measured on a subset of the study islands. Twelve months after the hurricane, species richness averaged over all islands rebounded to the last prehurricane value, but abundance attained only about half that value; this finding was remarkably similar to results found in an earlier study of spiders impacted by Hurricane Lili (1996) in a different Bahamian region. Nonetheless, in the next 3 years, species richness failed to increase further, part of its long-term decline at the study site. PMID:16452167

  13. Remembering the object you fear: brain potentials during recognition of spiders in spider-fearful individuals.

    PubMed

    Michalowski, Jaroslaw M; Weymar, Mathias; Hamm, Alfons O

    2014-01-01

    In the present study we investigated long-term memory for unpleasant, neutral and spider pictures in 15 spider-fearful and 15 non-fearful control individuals using behavioral and electrophysiological measures. During the initial (incidental) encoding, pictures were passively viewed in three separate blocks and were subsequently rated for valence and arousal. A recognition memory task was performed one week later in which old and new unpleasant, neutral and spider pictures were presented. Replicating previous results, we found enhanced memory performance and higher confidence ratings for unpleasant when compared to neutral materials in both animal fearful individuals and controls. When compared to controls high animal fearful individuals also showed a tendency towards better memory accuracy and significantly higher confidence during recognition of spider pictures, suggesting that memory of objects prompting specific fear is also facilitated in fearful individuals. In line, spider-fearful but not control participants responded with larger ERP positivity for correctly recognized old when compared to correctly rejected new spider pictures, thus showing the same effects in the neural signature of emotional memory for feared objects that were already discovered for other emotional materials. The increased fear memory for phobic materials observed in the present study in spider-fearful individuals might result in an enhanced fear response and reinforce negative beliefs aggravating anxiety symptomatology and hindering recovery.

  14. Attention training for reducing spider fear in spider-fearful individuals.

    PubMed

    Reese, Hannah E; McNally, Richard J; Najmi, Sadia; Amir, Nader

    2010-10-01

    Cognitive theorists propose that attentional biases for threatening information play an important role in the development and maintenance of anxiety disorders. If attentional biases for threat figure in the maintenance of anxiety, then the experimental reduction of the bias for threat (attention training) should reduce anxiety. We randomly assigned 41 spider-fearful individuals to receive either attention training (n=20) or control procedures (n=21). We used a modified dot-probe discrimination paradigm with photographs of spiders and cows to train attention. Training reduced attentional bias for spiders, but only temporarily. Although both groups declined in spider fear and avoidance, reduction in attentional bias did not produce significantly greater symptom reduction in the training group than in the control group. However, reduction in attentional bias predicted reduction in self-reported fear for the training group. The reduction in attentional bias for threat may have been insufficiently robust to produce symptom reduction greater than that produced by exposure to a live spider and spider photographs alone. Alternatively, attention training may be an unsuitable intervention for spider fear.

  15. SPIDER: Next Generation Chip Scale Imaging Sensor

    NASA Astrophysics Data System (ADS)

    Duncan, Alan; Kendrick, Rick; Thurman, Sam; Wuchenich, Danielle; Scott, Ryan P.; Yoo, S. J. B.; Su, Tiehui; Yu, Runxiang; Ogden, Chad; Proiett, Roberto

    The LM Advanced Technology Center and UC Davis are developing an Electro-Optical (EO) imaging sensor called SPIDER (Segmented Planar Imaging Detector for Electro-optical Reconnaissance) that provides a 10x to 100x size, weight, and power (SWaP) reduction alternative to the traditional bulky optical telescope and focal plane detector array. The substantial reductions in SWaP would reduce cost and/or provide higher resolution by enabling a larger aperture imager in a constrained volume. The SPIDER concept consists of thousands of direct detection white-light interferometers densely packed onto Photonic Integrated Circuits (PICs) to measure the amplitude and phase of the visibility function at spatial frequencies that span the full synthetic aperture. In other words, SPIDER would sample the object being imaged in the Fourier domain (i.e., spatial frequency domain), and then digitally reconstruct an image. The conventional approach for imaging interferometers requires complex mechanical delay lines to form the interference fringes. This results in designs that are not traceable to more than a few simultaneous spatial frequency measurements. SPIDER seeks to achieve this traceability by employing micron-=scale optical waveguides and nanophotonic structures fabricated on a PIC with micron-scale packing density to form the necessary interferometers. Prior LM IRAD and DARPA/NASA CRAD-funded SPIDER risk reduction experiments, design trades, and simulations have matured the SPIDER imager concept to a TRL 3 level. Current funding under the DARPA SPIDER Zoom program is maturing the underlying PIC technology for SPIDER to the TRL 4 level. This is done by developing and fabricating a second-generation PIC that is fully traceable to the multiple layers and low-power phase modulators required for higher-dimension waveguide arrays that are needed for higher field-of-view sensors. Our project also seeks to extend the SPIDER concept to add a zoom capability that would provide

  16. Optics of spider "sticky" orb webs

    NASA Astrophysics Data System (ADS)

    Kane, Deb M.; Staib, Gregory R.; Naidoo, Nishen; Little, Douglas J.; Herberstein, Marie E.

    2011-04-01

    Spider orb webs are known to produce colour displays in nature, both in reflection and transmission of sunlight, under certain illumination conditions. The cause of these colours has been the subject of speculation since the time of Newton. It has also been the topic of observational interpretation and some experiment which has proposed diffraction by the fine silks, scattering from rough/structured surfaces and thin film effects as the primary causes. We report systematic studies carried out using the silks of Australian orb web weaving spiders. Studies of both white light and laser light scattering/propagation by natural spider silks have definitively determined the primary cause of the colour displays is rainbows that can be understood by the application of geometric optics combined with new knowledge of the optical properties of the spider web strands, silks, and proteins as optical materials. Additionally, a range of microscopies (optical, AFM, optical surface profiling) show the silks to be optically flat. Overall, spider silks emerge as fascinating optical materials with high dispersion, high birefringence and the potential for future research to show they have high nonlinear optical coefficients. Their importance as a bioinspiration in optics is only just beginning to be realised. Their special optical properties have been achieved by ~136 million years of evolution driven by the need for the web to evade detection by insect prey.

  17. The elaborate structure of spider silk

    PubMed Central

    Römer, Lin

    2008-01-01

    Biomaterials, having evolved over millions of years, often exceed man-made materials in their properties. Spider silk is one outstanding fibrous biomaterial which consists almost entirely of large proteins. Silk fibers have tensile strengths comparable to steel and some silks are nearly as elastic as rubber on a weight to weight basis. In combining these two properties, silks reveal a toughness that is two to three times that of synthetic fibers like Nylon or Kevlar. Spider silk is also antimicrobial, hypoallergenic and completely biodegradable. This article focuses on the structure-function relationship of the characterized highly repetitive spider silk spidroins and their conformational conversion from solution into fibers. Such knowedge is of crucial importance to understanding the intrinsic properties of spider silk and to get insight into the sophisticated assembly processes of silk proteins. This review further outlines recent progress in recombinant production of spider silk proteins and their assembly into distinct polymer materials as a basis for novel products. PMID:19221522

  18. Exploring the shock response of spider webs.

    PubMed

    Tietsch, V; Alencastre, J; Witte, H; Torres, F G

    2016-03-01

    Spider orb-webs are designed to allow for quick energy absorption as well as the constraint of drastic oscillations occurring upon prey impact. Studies on spider silk illustrate its impressive mechanical properties and its capacity to be used as technical fibers in composite materials. Models have previously been used to study the mechanical properties of different silk fibers, but not the behavior of the spider web as a whole. Full spider webs have been impacted by a projectile and the transverse displacement was measured by means of a laser interferometer. The damping and stiffness of the entire webs were quantified considering the orb-web as a single-degree-of-freedom (SDOF) system. The amplitude, the period duration, and the energy dissipation of the oscillations have also been reported from the experiments. The analysis of the energy dissipation confirmed that the webs of orb-web spiders are optimized for the capture of a single or few large prey, rather than several small prey. The experiments also confirmed that the overall stiffness of the web displayed a non-linear behavior. Such non-linearity was also observed in the damping characteristics of the webs studied.

  19. Low genetic diversity and strong but shallow population differentiation suggests genetic homogenization by metapopulation dynamics in a social spider.

    PubMed

    Settepani, V; Bechsgaard, J; Bilde, T

    2014-12-01

    Mating systems and population dynamics influence genetic diversity and structure. Species that experience inbreeding and limited gene flow are expected to evolve isolated, divergent genetic lineages. Metapopulation dynamics with frequent extinctions and colonizations may, on the other hand, deplete and homogenize genetic variation, if extinction rate is sufficiently high compared to the effect of drift in local demes. We investigated these theoretical predictions empirically in social spiders that are highly inbred. Social spiders show intranest mating, female-biased sex ratio, and frequent extinction and colonization events, factors that deplete genetic diversity within nests and populations and limit gene flow. We characterized population genetic structure in Stegodyphus sarasinorum, a social spider distributed across the Indian subcontinent. Species-wide genetic diversity was estimated over approximately 2800 km from Sri Lanka to Himalayas, by sequencing 16 protein-coding nuclear loci. We found 13 SNPs in 6592 bp (π = 0.00045) indicating low species-wide nucleotide diversity. Three genetic lineages were strongly differentiated; however, only one fixed difference among them suggests recent divergence. This is consistent with a scenario of metapopulation dynamics that homogenizes genetic diversity across the species' range. Ultimately, low standing genetic variation may hamper a species' ability to track environmental change and render social inbreeding spiders 'evolutionary dead-ends'.

  20. Brown spider (Loxosceles genus) venom toxins: Evaluation of biological conservation by immune cross-reactivity.

    PubMed

    Buch, Daniela Regina; Souza, Fernanda Nunes; Meissner, Gabriel Otto; Morgon, Adriano Marcelo; Gremski, Luiza Helena; Ferrer, Valéria Pereira; Trevisan-Silva, Dilza; Matsubara, Fernando Hitomi; Boia-Ferreira, Mariana; Sade, Youssef Bacila; Chaves-Moreira, Daniele; Gremski, Waldemiro; Veiga, Silvio Sanches; Chaim, Olga Meiri; Senff-Ribeiro, Andrea

    2015-12-15

    Loxosceles spiders are responsible for serious human envenomations worldwide. The collection of symptoms found in victims after accidents is called loxoscelism and is characterized by two clinical conditions: cutaneous loxoscelism and systemic loxocelism. The only specific treatment is serum therapy, in which an antiserum produced with Loxosceles venom is administered to the victims after spider accidents. Our aim was to improve our knowledge, regarding the immunological relationship among toxins from the most epidemiologic important species in Brazil (Loxosceles intermedia, Loxosceles gaucho and Loxosceles laeta). Immunoassays using spider venoms and L. intermedia recombinant toxins were performed and their cross-reactivity assessed. The biological conservation of the main Loxosceles toxins (Phospholipases-D, Astacin-like metalloproteases, Hyaluronidase, ICK-insecticide peptide and TCTP-histamine releasing factor) were investigated. An in silico analysis of the putative epitopes was performed and is discussed on the basis of the experimental results. Our data is an immunological investigation in light of biological conservation throughout the Loxosceles genus. The results bring out new insights on brown spider venom toxins for study, diagnosis and treatment of loxoscelism and putative biotechnological applications concerning immune conserved features in the toxins.

  1. Fighting for the web: competition between female feather-legged spiders (Uloborus plumipes).

    PubMed

    Joel, Anna-Christin; Habedank, Anne; Hausen, Jonas; Mey, Jörg

    2017-04-01

    Most spider species are solitary, and among the few social interactions among them, resource competition between females has received little attention. We discovered that females of the feather-legged spider Uloborus plumipes invade the orb webs of conspecifics and compete for webs. Following observations in the wild, intruder-defender interactions were studied in a terrarium and in controlled laboratory experiments. We found that contests for orb webs occurred spontaneously between adult females. Competitive interactions in U. plumipes were characterized by an escalation of ritualized behaviors. In 27% of the contests the winner was determined by interactions at a distance, which involved behaviors that caused vibratory signaling on the web. The remaining interactions escalated to physical contact, and in 78% of these a fight occurred between the contestants. Using multivariate logistic regression we determined the factors that predicted the outcome of the contests: (i) Web ownership did not give the defender a competitive advantage. (ii) The difference in physical size between the competing spiders was the most important predictor for the outcome of web contests. (iii) Independent of body size, the display of certain behaviors, specifically the ability to reach the hub before the contestant and the frequency of attacks, increased the probability of winning. (iv) Winning or losing a fight did not affect the chances of winning subsequent contests. The interactions reported here provide a promising approach to investigate communication in spiders and to test theoretical models of intraspecific competition.

  2. Visual fields and eye morphology support color vision in a color-changing crab-spider.

    PubMed

    Insausti, Teresita C; Defrize, Jérémy; Lazzari, Claudio R; Casas, Jérôme

    2012-03-01

    Vision plays a major role in many spiders, being involved in prey hunting, orientation or substrate choice, among others. In Misumena vatia, which experiences morphological color changes, vision has been reported to be involved in substrate color matching. Electrophysiological evidence reveals that at least two types of photoreceptors are present in this species, but these data are not backed up by morphological evidence. This work analyzes the functional structure of the eyes of this spider and relates it to its color-changing abilities. A broad superposition of the visual field of the different eyes was observed, even between binocular regions of principal and secondary eyes. The frontal space is simultaneously analyzed by four eyes. This superposition supports the integration of the visual information provided by the different eye types. The mobile retina of the principal eyes of this spider is organized in three layers of three different types of rhabdoms. The third and deepest layer is composed by just one large rhabdom surrounded by dark screening pigments that limit the light entry. The three pairs of secondary eyes have all a single layer of rhabdoms. Our findings provide strong support for an involvement of the visual system in color matching in this spider.

  3. Hox genes in sea spiders (Pycnogonida) and the homology of arthropod head segments.

    PubMed

    Manuel, Michaël; Jager, Muriel; Murienne, Jérôme; Clabaut, Céline; Le Guyader, Hervé

    2006-01-01

    The pycnogonids (or sea spiders) are an enigmatic group of arthropods, classified in recent phylogenies as a sister-group of either euchelicerates (horseshoe crabs and arachnids), or all other extant arthropods. Because of their bizarre morpho-anatomy, homologies with other arthropod taxa have been difficult to assess. We review the main morphology-based hypotheses of correspondence between anterior segments of pycnogonids, arachnids and mandibulates. In an attempt to provide new relevant data to these controversial issues, we performed a PCR survey of Hox genes in two pycnogonid species, Endeis spinosa and Nymphon gracile, from which we could recover nine and six Hox genes, respectively. Phylogenetic analyses allowed to identify their orthology relationships. The Deformed gene from E. spinosa and the abdominal-A gene from N. gracile exhibit unusual sequence divergence in their homeodomains, which, in the latter case, may be correlated with the extreme reduction of the posterior region in pycnogonids. Expression patterns of two Hox genes (labial and Deformed) in the E. spinosa protonymphon larva are discussed. The anterior boundaries of their expression domains favour homology between sea spider chelifores, euchelicerates chelicerae and mandibulate (first) antennae, in contradistinction with previously proposed alternative schemes such as the protocerebral identity of sea spider chelifores or the absence of a deutocerebrum in chelicerates. In addition, while anatomical and embryological evidences suggest the possibility that the ovigers of sea spiders could be a duplicated pair of pedipalps, the Hox data support them as modified anterior walking legs, consistent with the classical views.

  4. ‘Natural experiment’ Demonstrates Top-Down Control of Spiders by Birds on a Landscape Level

    PubMed Central

    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

  5. Traditions in Spider Monkeys Are Biased towards the Social Domain

    PubMed Central

    Santorelli, Claire J.; Schaffner, Colleen M.; Campbell, Christina J.; Notman, Hugh; Pavelka, Mary S.; Weghorst, Jennifer A.; Aureli, Filippo

    2011-01-01

    Cross-site comparison studies of behavioral variation can provide evidence for traditions in wild species once ecological and genetic factors are excluded as causes for cross-site differences. These studies ensure behavior variants are considered within the context of a species' ecology and evolutionary adaptations. We examined wide-scale geographic variation in the behavior of spider monkeys (Ateles geoffroyi) across five long-term field sites in Central America using a well established ethnographic cross-site survey method. Spider monkeys possess a relatively rare social system with a high degree of fission-fusion dynamics, also typical of chimpanzees (Pan troglodytes) and humans (Homo sapiens). From the initial 62 behaviors surveyed 65% failed to meet the necessary criteria for traditions. The remaining 22 behaviors showed cross-site variation in occurrence ranging from absent through to customary, representing to our knowledge, the first documented cases of traditions in this taxon and only the second case of multiple traditions in a New World monkey species. Of the 22 behavioral variants recorded across all sites, on average 57% occurred in the social domain, 19% in food-related domains and 24% in other domains. This social bias contrasts with the food-related bias reported in great ape cross-site comparison studies and has implications for the evolution of human culture. No pattern of geographical radiation was found in relation to distance across sites. Our findings promote A. geoffroyi as a model species to investigate traditions with field and captive based experiments and emphasize the importance of the social domain for the study of animal traditions. PMID:21373196

  6. Traditions in spider monkeys are biased towards the social domain.

    PubMed

    Santorelli, Claire J; Schaffner, Colleen M; Campbell, Christina J; Notman, Hugh; Pavelka, Mary S; Weghorst, Jennifer A; Aureli, Filippo

    2011-02-23

    Cross-site comparison studies of behavioral variation can provide evidence for traditions in wild species once ecological and genetic factors are excluded as causes for cross-site differences. These studies ensure behavior variants are considered within the context of a species' ecology and evolutionary adaptations. We examined wide-scale geographic variation in the behavior of spider monkeys (Ateles geoffroyi) across five long-term field sites in Central America using a well established ethnographic cross-site survey method. Spider monkeys possess a relatively rare social system with a high degree of fission-fusion dynamics, also typical of chimpanzees (Pan troglodytes) and humans (Homo sapiens). From the initial 62 behaviors surveyed 65% failed to meet the necessary criteria for traditions. The remaining 22 behaviors showed cross-site variation in occurrence ranging from absent through to customary, representing to our knowledge, the first documented cases of traditions in this taxon and only the second case of multiple traditions in a New World monkey species. Of the 22 behavioral variants recorded across all sites, on average 57% occurred in the social domain, 19% in food-related domains and 24% in other domains. This social bias contrasts with the food-related bias reported in great ape cross-site comparison studies and has implications for the evolution of human culture. No pattern of geographical radiation was found in relation to distance across sites. Our findings promote A. geoffroyi as a model species to investigate traditions with field and captive based experiments and emphasize the importance of the social domain for the study of animal traditions.

  7. Coincidental intraguild predation by caterpillars on spider mites.

    PubMed

    Shirotsuka, Kanako; Yano, Shuichi

    2012-01-29

    Intraguild predation (IGP) is defined as the killing and eating of prey species by a predator that also can utilize the resources of the prey. It is mainly reported among carnivores that share common herbivorous prey. However, a large chewing herbivore could prey upon sedentary and/or micro herbivores in addition to utilizing a host plant. To investigate such coincidental IGP, we observed the behavioral responses of the polyphagous mite Tetranychus kanzawai Kishida (Acari: Tetranychidae) when its host plant Cayratia japonica (Thunb.) Gagnep. (Vitaceae) was attacked by hornworms, Theretra japonica Boisduval (Sphingidae) and T. oldenlandiae Fabricius (Sphingidae). We also examined an interaction between the oligophagous mite Panonychus citri McGregor (Acari: Tetranychidae) and caterpillars of the swallowtail Papilio xuthus L. (Papilionidae) that share citrus plants as their main food source. Although all T. kanzawai and some active stage P. citri tried to escape from the coincidental IGP, some were consumed together with eggs, quiescent mites, and host plant leaves, suggesting that coincidental IGP occurs on spider mites in the wild. Moreover, neither hornworms nor swallowtail caterpillars distinguished between spider mite-infested and uninfested leaves, suggesting that the mite-infested leaves do not discourage caterpillar feeding. The reasons that the mites have no effective defense against coincidental IGP other than escaping are discussed.

  8. Spider web-inspired acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Miniaci, Marco; Krushynska, Anastasiia; Movchan, Alexander B.; Bosia, Federico; Pugno, Nicola M.

    2016-08-01

    Spider silk is a remarkable example of bio-material with superior mechanical characteristics. Its multilevel structural organization of dragline and viscid silk leads to unusual and tunable properties, extensively studied from a quasi-static point of view. In this study, inspired by the Nephila spider orb web architecture, we propose a design for mechanical metamaterials based on its periodic repetition. We demonstrate that spider-web metamaterial structure plays an important role in the dynamic response and wave attenuation mechanisms. The capability of the resulting structure to inhibit elastic wave propagation in sub-wavelength frequency ranges is assessed, and parametric studies are performed to derive optimal configurations and constituent mechanical properties. The results show promise for the design of innovative lightweight structures for tunable vibration damping and impact protection, or the protection of large scale infrastructure such as suspended bridges.

  9. Optically probing torsional superelasticity in spider silks

    SciTech Connect

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

    2013-11-11

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2−3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  10. Impact of Canopy Openness on Spider Communities: Implications for Conservation Management of Formerly Coppiced Oak Forests.

    PubMed

    Košulič, Ondřej; Michalko, Radek; Hula, Vladimír

    2016-01-01

    Traditional woodland management created a mosaic of differently aged patches providing favorable conditions for a variety of arthropods. After abandonment of historical ownership patterns and traditional management and the deliberate transformation to high forest after World War II, large forest areas became darker and more homogeneous. This had significant negative consequences for biodiversity. An important question is whether even small-scale habitat structures maintained by different levels of canopy openness in abandoned coppiced forest may constitute conditions suitable for forest as well as open habitat specialists. We investigated the effect of canopy openness in former traditionally coppiced woodlands on the species richness, functional diversity, activity density, conservation value, and degree of rareness of epigeic spiders. In each of the eight studied locations, 60-m-long transect was established consisting of five pitfall traps placed at regular 15 m intervals along the gradient. Spiders were collected from May to July 2012. We recorded 90 spider species, including high proportions of xeric specialists (40%) and red-listed threatened species (26%). The peaks of conservation indicators, as well as spider community abundance, were shifted toward more open canopies. On the other hand, functional diversity peaked at more closed canopies followed by a rapid decrease with increasing canopy openness. Species richness was highest in the middle of the canopy openness gradient, suggesting an ecotone effect. Ordinations revealed that species of conservation concern tended to be associated with sparse and partly opened canopy. The results show that the various components of biodiversity peaked at different levels of canopy openness. Therefore, the restoration and suitable forest management of such conditions will retain important diversification of habitats in formerly coppiced oak forest stands. We indicate that permanent presence of small-scale improvements

  11. Impact of Canopy Openness on Spider Communities: Implications for Conservation Management of Formerly Coppiced Oak Forests

    PubMed Central

    Košulič, Ondřej; Michalko, Radek; Hula, Vladimír

    2016-01-01

    Traditional woodland management created a mosaic of differently aged patches providing favorable conditions for a variety of arthropods. After abandonment of historical ownership patterns and traditional management and the deliberate transformation to high forest after World War II, large forest areas became darker and more homogeneous. This had significant negative consequences for biodiversity. An important question is whether even small-scale habitat structures maintained by different levels of canopy openness in abandoned coppiced forest may constitute conditions suitable for forest as well as open habitat specialists. We investigated the effect of canopy openness in former traditionally coppiced woodlands on the species richness, functional diversity, activity density, conservation value, and degree of rareness of epigeic spiders. In each of the eight studied locations, 60-m-long transect was established consisting of five pitfall traps placed at regular 15 m intervals along the gradient. Spiders were collected from May to July 2012. We recorded 90 spider species, including high proportions of xeric specialists (40%) and red-listed threatened species (26%). The peaks of conservation indicators, as well as spider community abundance, were shifted toward more open canopies. On the other hand, functional diversity peaked at more closed canopies followed by a rapid decrease with increasing canopy openness. Species richness was highest in the middle of the canopy openness gradient, suggesting an ecotone effect. Ordinations revealed that species of conservation concern tended to be associated with sparse and partly opened canopy. The results show that the various components of biodiversity peaked at different levels of canopy openness. Therefore, the restoration and suitable forest management of such conditions will retain important diversification of habitats in formerly coppiced oak forest stands. We indicate that permanent presence of small-scale improvements

  12. Short-Term Response of Soil Spiders to Cover-Crop Removal in an Organic Olive Orchard in a Mediterranean Setting

    PubMed Central

    Cárdenas, Manuel; Castro, Juan; Campos, Mercedes

    2012-01-01

    This study shows that disturbance caused by cover-crop removal (CCR) in an organic olive orchard affects ground-spider populations. The effect of CCR on various organic olive-orchard plots was assessed by monitoring the abundance and diversity of ground-dwelling spiders. Covered plots in the organic olive orchard were compared with uncovered plots where the covers had been removed mechanically. CCR positively affected the most abundant spider species Zodarion styliferum (Simon) (Araneae: Zodariidae) as well as other species of running spiders belonging to the families Gnaphosidae and Lycosidae. Over time, the two types of plots did not significantly differ in diversity or dominance. Similarly, no differences were detected between the study plots in terms of the distribution of individuals when a cluster-similarity analysis was performed. This lack of difference in diversity might be due to the spatial scale used in the study or climatology. Because of their general effects, CCR profoundly changed the abundance of spiders in the olive orchard, but with no clear impact on spider diversity. PMID:22938154

  13. Mosaic evolution of silk genes in Aliatypus trapdoor spiders (mygalomorphae, antrodiaetidae).

    PubMed

    Starrett, James; Hayashi, Cheryl Y

    2013-04-01

    Spider silk genes are composed mostly of repetitive sequence that is flanked by non-repetitive terminal regions. Inferences about the evolutionary processes that influenced silk genes have largely been made from analyses using distantly related taxa and ancient silk gene duplicates. These studies have relied on comparisons across the conserved non-repetitive terminal regions to determine orthologous and paralogous relationships, as well as the influence of selection on silk genes. While the repetitive region heavily influences silk fiber mechanical properties, few molecular evolutionary analyses have been conducted on this region due to difficulty in determining homology. Here, we sample internal repetitive and carboxy terminal regions from all extant species of the trapdoor spider genus, Aliatypus. Aliatypus spiders are highly dispersal limited and rely on their silk lined burrow for protection. We determine positional homology across species for the carboxy terminal regions and relative positional homology for the internal repetitive regions. Gene trees based on each of these regions are in good agreement with the Aliatypus species tree, which indicates we sampled single spidroin orthologs in each species. In addition, we find that purifying selection and concerted evolution have acted to conserve Aliatypus spidroin internal repetitive regions. In contrast, selection testing identifies evidence of sites that evolved under positive selection and amino acid replacements that result in radical physicochemical changes in the carboxy terminal region. These findings indicate that comparison of spidroin orthologs across a comprehensive sample of congenerics reveal molecular evolutionary patterns obscured from studies using higher-level sampling of silk encoding genes.

  14. First Record of the Mediterranean Recluse Spider Loxosceles rufescens (Araneae: Sicariidae) from Iran

    PubMed Central

    Zamani, Alireza; Rafinejad, Javad

    2014-01-01

    Loxosceles rufescens, commonly known as the Mediterranean Recluse or Mediterranean Fiddle-Back Spider is recorded from Iran for the first time. The genus Loxosceles contains 103 accepted species, two of them (including L. rufescens) are cosmopolitan. All Loxosceles species tested so far possess necrotic venoms, which is a unique characteristic among the Order Araneae. Considering this characteristic, it is of medical importance to determine a specific geographical distribution of these spiders. Collecting methods include visual inspection and direct hand collecting. All of the specimens were collected in Tehran. Six specimens of both sexes were collected from parks, houses and apartments. The characteristics of the genus, which are the unique arrangement of six eyes in three diads, the violin shaped mark on the cephalothorax, and the short tibia of adult male palpi with narrow base and it’s embolus which is about as long as the width of the globular bulb were observed and recorded. Having the cytotoxicity of the venom and its urban distribution in mind, L. rufescens is probably among the more important spider species of Iran. Since there are no reports of loxoscelism from Iran, we assume that the bites are either infrequent or misdiagnosed. Therefore further studies are needed to clarify the medical importance degree of this species. PMID:26114138

  15. Spider Invasion Across the Galaxy

    NASA Astrophysics Data System (ADS)

    Hui, Chung-Yue

    2014-06-01

    The nature of the exotic stellar corpses which reincarnate by consuming their companion is reviewed. Apart from sucking life from their partners, they are actually eating the doomed companions away by their deadly and powerful particle/radiation beams. Such situation resembles that a female ¡°black widow¡± spider that eats its mate after mating. These celestial zombies are called - Millisecond pulsars (MSPs). In this review article, I will focus on the effort of Fermi Asian Network (FAN) in exploring these intricating objects over the last five years. Two special classes of MSPs are particularly striking. Since Fermi Gamma-ray Space Telescope has started surveying the gamma?ray sky, the population of ¡°black widows¡± has been boosted. Another dramatic class is so-called ¡°redbacks¡± (Australian cousin of ¡°black widows¡±) which has just emerged in the last few years. These MSPs provide us with a long-sought missing link in understanding the transition between accretion-powered and rotation-powered systems. The strategy of hunting MSPs through mulitwavelength observations of the unidentified Fermi objects is also reviewed.

  16. First record of the mygalomorph spider family Paratropididae (Arachnida, Araneae) in North America with the description of a new species of Paratropis Simon from Mexico, and with new ultramorphological data for the family

    PubMed Central

    Valdez-Mondragón, Alejandro; Mendoza, Jorge I.; Francke, Oscar F.

    2014-01-01

    Abstract A new species of the genus Paratropis is described from North America: Paratropis tuxtlensis sp. n., from a tropical rainforest in Veracruz, Mexico. This is the fifth Paratropis and the tenth paratropidid species described and the first North American record of this Neotropical family. The species is described based on adult males and females, and juveniles. The juveniles show ontogenetic variation in the number of cuspules on the labium and endites, and in the number and position of leg trichobothria. This is the second Paratropis species, and the third paratropidid known from both sexes. The scanning electron photographs (SEM) reveal new morphological data and contribute to the knowledge of the family. PMID:25061343

  17. Colouration in crab spiders: substrate choice and prey attraction.

    PubMed

    Heiling, Astrid M; Chittka, Lars; Cheng, Ken; Herberstein, Marie E

    2005-05-01

    Australian crab spiders Thomisus spectabilis ambush pollinating insects, such as honeybees (Apis mellifera) on flowers, and can change their body colour between yellow and white. It is traditionally assumed that the spiders change their colour to match the flower colour, thus rendering them cryptic to insect prey. Here, we test this assumption combining state-of-the-art knowledge of bee vision and behavioural experiments. In the field, yellow spiders are only found on yellow daisies (Chrysanthemum frutescens), whereas white spiders are found on yellow and white daisies. These field patterns were confirmed in the laboratory. When given the choice between white and yellow daisies, yellow spiders preferred yellow daisies, whereas white spiders showed only a slight but non-significant preference for white flowers. Thus, T. spectabilis select background colours according to their own body colour. When viewed from a distance, bees use an achromatic signal produced by their green receptors for target detection. Through this visual channel, white spiders on white flowers, and yellow spiders on yellow flowers are virtually undetectable. From a closer distance of a few centimetres, when bees evaluate colour contrast, the combination of spider colour against different flower backgrounds affected the response of honeybees, but not in ways predicted by a classical crypsis/conspicuousness interpretation. Yellow spiders on yellow flowers are not perfectly matched when interpreted through the colour vision of a honeybee. Nevertheless, honeybees showed indifference to the presence of a spider, equally landing on vacant or spider-occupied flowers. Likewise, white spiders are poorly hidden on white flowers, as white spiders reflect ultraviolet light strongly, while white flowers do not. Surprisingly, bees are attracted to this contrast, and significantly more honeybees preferred white flowers occupied by white spiders. White spiders on yellow flowers produce the highest colour

  18. Spider Silk: Mother Nature's Bio-Superlens

    NASA Astrophysics Data System (ADS)

    Monks, James N.; Yan, Bing; Hawkins, Nicholas; Vollrath, Fritz; Wang, Zengbo

    2016-09-01

    This paper demonstrates a possible new microfiber bio near field lens that uses minor ampullate spider silk,spun from the Nephila edulis spider, to create a real time image of a surface using near field optical techniques. The microfiber bio lens is the world's first natural superlens created by exploring biological materials. The resolution of the surface image overcomes the diffraction limit, with the ability to resolve patterns at 100 nm under a standard white light source in reflection mode. This resolution offers further developments in superlens technology and paves the way for new bio optics.

  19. Spider silk has an ice nucleation activity.

    PubMed

    Murase, N; Ruike, M; Matsunaga, N; Hayakawa, M; Kaneko, Y; Ono, Y

    2001-03-01

    Several ice nucleating substances have been identified, which exist in vivo or can be extracted from biological materials. Spider silk, which has a strong ability for water condensation, has also been found to possess an ice nucleation activity. The freezing temperature of water droplets was higher in the presence than in the absence of spider silk. Moreover, by means of environmental scanning electron microscopy, it was observed that the activity is not due to foreign matter attached to the silk but to the silk fibroin itself.

  20. Upside-down spiders build upside-down orb webs: web asymmetry, spider orientation and running speed in Cyclosa.

    PubMed

    Nakata, Kensuke; Zschokke, Samuel

    2010-10-07

    Almost all spiders building vertical orb webs face downwards when sitting on the hubs of their webs, and their webs exhibit an up-down size asymmetry, with the lower part of the capture area being larger than the upper. However, spiders of the genus Cyclosa, which all build vertical orb webs, exhibit inter- and intraspecific variation in orientation. In particular, Cyclosa ginnaga and C. argenteoalba always face upwards, and C. octotuberculata always face downwards, whereas some C. confusa face upwards and others face downwards or even sideways. These spiders provide a unique opportunity to examine why most spiders face downwards and have asymmetrical webs. We found that upward-facing spiders had upside-down webs with larger upper parts, downward-facing spiders had normal webs with larger lower parts and sideways-facing spiders had more symmetrical webs. Downward-facing C. confusa spiders were larger than upward- and sideways-facing individuals. We also found that during prey attacks, downward-facing spiders ran significantly faster downwards than upwards, which was not the case in upward-facing spiders. These results suggest that the spider's orientation at the hub and web asymmetry enhance its foraging efficiency by minimizing the time to reach prey trapped in the web.

  1. Male adaptations to minimize sexual cannibalism during reproduction in the funnel-web spider Hololena curta.

    PubMed

    Xiao, Yong-Hong; Zunic-Kosi, Alenka; Zhang, Long-Wa; Prentice, Thomas R; McElfresh, J Steven; Chinta, Satya P; Zou, Yun-Fan; Millar, Jocelyn G

    2015-12-01

    Males of many spider species risk being attacked and cannibalized while searching for, courting, and mating with conspecific females. However, there are exceptions. We show that the funnel-web spider, Hololena curta, has 3 adaptations that minimize risk to males during courtship and mating, and enhance reproductive success. First, males detected chemical or tactile signals associated with webs of virgin females, and differentiated them from webs of mated females, enabling males to increase encounter rates with virgin females and avoid aggressive mated females. Second, males produced stereotyped vibrational signals during courting which induced female quiescence and suppressed female aggression. Third, when touched by males, sexually receptive females entered a cataleptic state, allowing males to safely approach and copulate. Because males can mate multiple times and the sex ratio in natural populations of H. curta is female biased, overall reproductive output is likely increased by males of this species avoiding sexual cannibalism.

  2. Loss of genetic variability in social spiders: genetic and phylogenetic consequences of population subdivision and inbreeding.

    PubMed

    Agnarsson, I; Avilés, L; Maddison, W P

    2013-01-01

    The consequences of population subdivision and inbreeding have been studied in many organisms, particularly in plants. However, most studies focus on the short-term consequences, such as inbreeding depression. To investigate the consequences of both population fragmentation and inbreeding for genetic variability in the longer term, we here make use of a natural inbreeding experiment in spiders, where sociality and accompanying population subdivision and inbreeding have evolved repeatedly. We use mitochondrial and nuclear data to infer phylogenetic relationships among 170 individuals of Anelosimus spiders representing 23 species. We then compare relative mitochondrial and nuclear genetic variability of the inbred social species and their outbred relatives. We focus on four independently derived social species and four subsocial species, including two outbred-inbred sister species pairs. We find that social species have 50% reduced mitochondrial sequence divergence. As inbreeding is not expected to reduce genetic variability in the maternally inherited mitochondrial genome, this suggests the loss of variation due to strong population subdivision, founder effects, small effective population sizes (colonies as individuals) and lineage turnover. Social species have < 10% of the nuclear genetic variability of the outbred species, also suggesting the loss of genetic variability through founder effects and/or inbreeding. Inbred sociality hence may result in reduction in variability through various processes. Sociality in most Anelosimus species probably arose relatively recently (0.1-2 mya), with even the oldest social lineages having failed to diversify. This is consistent with the hypothesis that inbred spider sociality represents an evolutionary dead end. Heterosis underlies a species potential to respond to environmental change and/or disease. Inbreeding and loss of genetic variability may thus limit diversification in social Anelosimus lineages and similarly pose a

  3. Loss of genetic variability in social spiders: genetic and phylogenetic consequences of population subdivision and inbreeding

    PubMed Central

    Agnarsson, I; Avilés, L; Maddison, W P

    2013-01-01

    The consequences of population subdivision and inbreeding have been studied in many organisms, particularly in plants. However, most studies focus on the short-term consequences, such as inbreeding depression. To investigate the consequences of both population fragmentation and inbreeding for genetic variability in the longer term, we here make use of a natural inbreeding experiment in spiders, where sociality and accompanying population subdivision and inbreeding have evolved repeatedly. We use mitochondrial and nuclear data to infer phylogenetic relationships among 170 individuals of Anelosimus spiders representing 23 species. We then compare relative mitochondrial and nuclear genetic variability of the inbred social species and their outbred relatives. We focus on four independently derived social species and four subsocial species, including two outbred–inbred sister species pairs. We find that social species have 50% reduced mitochondrial sequence divergence. As inbreeding is not expected to reduce genetic variability in the maternally inherited mitochondrial genome, this suggests the loss of variation due to strong population subdivision, founder effects, small effective population sizes (colonies as individuals) and lineage turnover. Social species have < 10% of the nuclear genetic variability of the outbred species, also suggesting the loss of genetic variability through founder effects and/or inbreeding. Inbred sociality hence may result in reduction in variability through various processes. Sociality in most Anelosimus species probably arose relatively recently (0.1–2 mya), with even the oldest social lineages having failed to diversify. This is consistent with the hypothesis that inbred spider sociality represents an evolutionary dead end. Heterosis underlies a species potential to respond to environmental change and/or disease. Inbreeding and loss of genetic variability may thus limit diversification in social Anelosimus lineages and similarly pose

  4. Peptidomic and transcriptomic profiling of four distinct spider venoms

    PubMed Central

    Oldrati, Vera; Koua, Dominique; Allard, Pierre-Marie; Hulo, Nicolas; Arrell, Miriam; Nentwig, Wolfgang; Lisacek, Frédérique; Wolfender, Jean-Luc; Kuhn-Nentwig, Lucia; Stöcklin, Reto

    2017-01-01

    Venom based research is exploited to find novel candidates for the development of innovative pharmacological tools, drug candidates and new ingredients for cosmetic and agrochemical industries. Moreover, venomics, as a well-established approach in systems biology, helps to elucidate the genetic mechanisms of the production of such a great molecular biodiversity. Today the advances made in the proteomics, transcriptomics and bioinformatics fields, favor venomics, allowing the in depth study of complex matrices and the elucidation even of minor compounds present in minute biological samples. The present study illustrates a rapid and efficient method developed for the elucidation of venom composition based on NextGen mRNA sequencing of venom glands and LC-MS/MS venom proteome profiling. The analysis of the comprehensive data obtained was focused on cysteine rich peptide toxins from four spider species originating from phylogenetically distant families for comparison purposes. The studied species were Heteropoda davidbowie (Sparassidae), Poecilotheria formosa (Theraphosidae), Viridasius fasciatus (Viridasiidae) and Latrodectus mactans (Theridiidae). This led to a high resolution profiling of 284 characterized cysteine rich peptides, 111 of which belong to the Inhibitor Cysteine Knot (ICK) structural motif. The analysis of H. davidbowie venom revealed a high richness in term of venom diversity: 95 peptide sequences were identified; out of these, 32 peptides presented the ICK structural motif and could be classified in six distinct families. The profiling of P. formosa venom highlighted the presence of 126 peptide sequences, with 52 ICK toxins belonging to three structural distinct families. V. fasciatus venom was shown to contain 49 peptide sequences, out of which 22 presented the ICK structural motif and were attributed to five families. The venom of L. mactans, until now studied for its large neurotoxins (Latrotoxins), revealed the presence of 14 cysteine rich

  5. Insects from the grazing food web favoured the evolutionary habitat shift to bright environments in araneoid spiders.

    PubMed

    Miyashita, Tadashi; Shimazaki, Aya

    2006-12-22

    The Araneoidea comprises a diverse group of web-building spiders, and part of this diversity is believed attributable to habitat expansion to bright environments. We clarified the fitness-related advantages of living in such environments by examining prey availability and the growth rates of 10 species in three families inhabiting grassland (bright) and forest understory (dim) habitats. Spiders in the grassland habitat captured more prey, derived mainly from the grazing food web, than those in the forest-floor environment, and this difference was manifested in their growth rate. Independent contrasts indicated that increased utilization of insects from the grazing food web led to an evolutionary increase in adult body size. These results suggest that the shift to bright environments enabled araneoid spiders to evolve diverse life-history traits, including rapid growth and large size, which were not possible in dim environments.

  6. Intraguild interactions among three spider mite predators: predation preference and effects on juvenile development and oviposition.

    PubMed

    Rahmani, Hasan; Daneshmandi, Aliakbar; Walzer, Andreas

    2015-12-01

    A first step to evaluate potential negative effects of intraguild predation (IGP) when using multiple predators against a pest species is the determination of the predation behavior of the predators and the nutritional value of intraguild (IG) prey in terms of development and oviposition. Here, we investigated the predation preference of the female predatory mites Neoseiulus californicus, Typhlodromus bagdasarjani and Phytoseius plumifer, when having choice between larvae of the two other predatory mite species (IG prey) with and without extraguild prey, the spider mite Tetranychus urticae (EG prey). Additionally, we evaluated the juvenile development and oviposition of the three predator species when provided with larvae from each other species. Irrespective of EG prey, IG prey species affected neither the first attack nor attack times of the three female IG predator species. The IG predation rates of the predator females, however, were influenced by prey species in the absence of EG prey. Neoseiulus californicus females killed more P. plumifer than T. bagdasarjani larvae, whereas T. bagdasarjani and P. plumifer females killed more N. californicus than P. plumifer and T. bagdasarjani larvae, respectively. All IG predator species consumed significantly more EG than IG prey. IG prey species did not influence juvenile and adult survival probabilities of the IG predators. We conclude that IGP is a weak force among the three predators and the potential consequences of IGP should not result in the elimination of one by another tested predatory mite species at least in the presence of spider mites.

  7. Chitin in the silk gland ducts of the spider Nephila edulis and the silkworm Bombyx mori.

    PubMed

    Davies, Gwilym J G; Knight, David P; Vollrath, Fritz

    2013-01-01

    Here we report the detection and localisation of chitin in the cuticle of the spinning ducts of both the spider Nephila edulis and the silkworm Bombyx mori. Our observations demonstrate that the duct walls of both animals contain chitin notwithstanding totally independent evolutionary pathways of the systems. We conclude that chitin may well be an essential component for the construction of spinning ducts; we further conclude that in both species chitin may indicate the evolutionary origin of the spinning ducts.

  8. Spiders on a Hot Volcanic Roof: Colonisation Pathways and Phylogeography of the Canary Islands Endemic Trap-Door Spider Titanidiops canariensis (Araneae, Idiopidae)

    PubMed Central

    Opatova, Vera; Arnedo, Miquel A.

    2014-01-01

    Studies conducted on volcanic islands have greatly contributed to our current understanding of how organisms diversify. The Canary Islands archipelago, located northwest of the coast of northern Africa, harbours a large number of endemic taxa. Because of their low vagility, mygalomorph spiders are usually absent from oceanic islands. The spider Titanidiops canariensis, which inhabits the easternmost islands of the archipelago, constitutes an exception to this rule. Here, we use a multi-locus approach that combines three mitochondrial and four nuclear genes to investigate the origins and phylogeography of this remarkable trap-door spider. We provide a timeframe for the colonisation of the Canary Islands using two alternative approaches: concatenation and species tree inference in a Bayesian relaxed clock framework. Additionally, we investigate the existence of cryptic species on the islands by means of a Bayesian multi-locus species delimitation method. Our results indicate that T. canariensis colonised the Canary Islands once, most likely during the Miocene, although discrepancies between the timeframes from different approaches make the exact timing uncertain. A complex evolutionary history for the species in the archipelago is revealed, which involves two independent colonisations of Fuerteventura from the ancestral range of T. canariensis in northern Lanzarote and a possible back colonisation of southern Lanzarote. The data further corroborate a previously proposed volcanic refugium, highlighting the impact of the dynamic volcanic history of the island on the phylogeographic patterns of the endemic taxa. T. canariensis includes at least two different species, one inhabiting the Jandia peninsula and central Fuerteventura and one spanning from central Fuerteventura to Lanzarote. Our data suggest that the extant northern African Titanidiops lineages may have expanded to the region after the islands were colonised and, hence, are not the source of colonisation. In

  9. Spider Trait Assembly Patterns and Resilience under Fire-Induced Vegetation Change in South Brazilian Grasslands

    PubMed Central

    Podgaiski, Luciana R.; Joner, Fernando; Lavorel, Sandra; Moretti, Marco; Ibanez, Sebastien; Mendonça, Milton de S.; Pillar, Valério D.

    2013-01-01

    Disturbances induce changes on habitat proprieties that may filter organism's functional traits thereby shaping the structure and interactions of many trophic levels. We tested if communities of predators with foraging traits dependent on habitat structure respond to environmental change through cascades affecting the functional traits of plants. We monitored the response of spider and plant communities to fire in South Brazilian Grasslands using pairs of burned and unburned plots. Spiders were determined to the family level and described in feeding behavioral and morphological traits measured on each individual. Life form and morphological traits were recorded for plant species. One month after fire the abundance of vegetation hunters and the mean size of the chelicera increased due to the presence of suitable feeding sites in the regrowing vegetation, but irregular web builders decreased due to the absence of microhabitats and dense foliage into which they build their webs. Six months after fire rosette-form plants with broader leaves increased, creating a favourable habitat for orb web builders which became more abundant, while graminoids and tall plants were reduced, resulting in a decrease of proper shelters and microclimate in soil surface to ground hunters which became less abundant. Hence, fire triggered changes in vegetation structure that lead both to trait-convergence and trait-divergence assembly patterns of spiders along gradients of plant biomass and functional diversity. Spider individuals occurring in more functionally diverse plant communities were more diverse in their traits probably because increased possibility of resource exploitation, following the habitat heterogeneity hypothesis. Finally, as an indication of resilience, after twelve months spider communities did not differ from those of unburned plots. Our findings show that functional traits provide a mechanistic understanding of the response of communities to environmental change

  10. Gustatory responsiveness to the 20 proteinogenic amino acids in the spider monkey (Ateles geoffroyi).

    PubMed

    Larsson, Jenny; Maitz, Anna; Hernandez Salazar, Laura Teresa; Laska, Matthias

    2014-03-29

    The gustatory responsiveness of four adult spider monkeys to the 20 proteinogenic amino acids was assessed in two-bottle preference tests of brief duration (1min). We found that Ateles geoffroyi responded with significant preferences for seven amino acids (glycine, l-proline, l-alanine, l-serine, l-glutamic acid, l-aspartic acid, and l-lysine) when presented at a concentration of 100mM and/or 200mM and tested against water. At the same concentrations, the animals significantly rejected five amino acids (l-tryptophan, l-tyrosine, l-valine, l-cysteine, and l-isoleucine) and were indifferent to the remaining tastants. Further, the results show that the spider monkeys discriminated concentrations as low as 0.2mM l-lysine, 2mM l-glutamic acid, 10mM l-proline, 20mM l-valine, 40mM glycine, l-serine, and l-aspartic acid, and 80mM l-alanine from the alternative stimulus, with individual animals even scoring lower threshold values. A comparison between the taste qualities of the proteinogenic amino acids as described by humans and the preferences and aversions observed in the spider monkeys suggests a fairly high degree of agreement in the taste quality perception of these tastants between the two species. A comparison between the taste preference thresholds obtained with the spider monkeys and taste detection thresholds reported in human subjects suggests that the taste sensitivity of A. geoffroyi for the amino acids tested here might match that of Homo sapiens. The results support the assumption that the taste responses of spider monkeys to proteinogenic amino acids might reflect an evolutionary adaptation to their frugivorous and thus protein-poor diet.

  11. Spider-fed bromeliads: seasonal and interspecific variation in plant performance

    PubMed Central

    Gonçalves, Ana Zangirólame; Mercier, Helenice; Mazzafera, Paulo; Romero, Gustavo Quevedo

    2011-01-01

    Background and Aims Several animals that live on bromeliads can contribute to plant nutrition through nitrogen provisioning (digestive mutualism). The bromeliad-living spider Psecas chapoda (Salticidae) inhabits and breeds on Bromelia balansae in regions of South America, but in specific regions can also appear on Ananas comosus (pineapple) plantations and Aechmea distichantha. Methods Using isotopic and physiological methods in greenhouse experiments, the role of labelled (15N) spider faeces and Drosophila melanogaster flies in the nutrition and growth of each host plant was evaluated, as well as seasonal variation in the importance of this digestive mutualism. Key Results Spiders contributed 0·6 ± 0·2 % (mean ± s.e.; dry season) to 2·7 ± 1 % (wet season) to the total nitrogen in B. balansae, 2·4 ± 0·4 % (dry) to 4·1 ± 0·3 % (wet) in An. comosus and 3·8 ± 0·4 % (dry) to 5 ± 1 % (wet) in Ae. distichantha. In contrast, flies did not contribute to the nutrition of these bromeliads. Chlorophylls and carotenoid concentrations did not differ among treatments. Plants that received faeces had higher soluble protein concentrations and leaf growth (RGR) only during the wet season. Conclusions These results indicate that the mutualism between spiders and bromeliads is seasonally restricted, generating a conditional outcome. There was interspecific variation in nutrient uptake, probably related to each species' performance and photosynthetic pathways. Whereas B. balansae seems to use nitrogen for growth, Ae. distichantha apparently stores nitrogen for stressful nutritional conditions. Bromeliads absorbed more nitrogen coming from spider faeces than from flies, reinforcing the beneficial role played by predators in these digestive mutualisms. PMID:21385776

  12. Taxonomic revision of the American spider genus Arachosia (Araneae: Anyphaenidae).

    PubMed

    Rubio, Gonzalo D; Ramírez, Martín J

    2015-03-17

    We review the American spider genus Arachosia O.P.-Cambridge, and present a descriptive taxonomic study with a comparative dichotomous key including 21 species, of which seven are newly described (A. avalosi sp. nov., A. carancho sp. nov., A. kapiipeoi sp. nov., A. magna sp. nov., A. monserrate sp. nov., A. pinhalito sp. nov. and A. tungurahua sp. nov.). Four species names are considered nomina dubia: Oxysoma dubium Berland, Gayenna duplovittata Mello-Leitão, Oxysoma polytrichium Mello-Leitão, and Arachosia sulfurea Mello-Leitão. Arachosia bonneti (Mello-Leitão) is newly synonymized with A. albiventris Mello-Leitão, and A. mezenioides Mello-Leitão with A. freiburgensis Keyserling. Previous problems with the identification of species in a species complex including A. cubana (Banks) are resolved. A disjunct distributional pattern is reported for A. kapiipeoi sp. nov.; a preliminary phylogenetic analysis based on mitochondrial COI sequences shows that these may correspond with two cryptic species. In this contribution, grassland and forests are discussed as the two main habitats inhabited by species of Arachosia. Finally, we propose a hypothesis of matching sexes based on functionality of some genital structures, involving sclerites of the male copulatory organ with structures of the epigyne: the prolateral projection on the primary conductor of the male would have a direct interaction with the lateral projections of the anterior pouch on the median epigynal field of females.

  13. Tree diversity promotes functional dissimilarity and maintains functional richness despite species loss in predator assemblages.

    PubMed

    Schuldt, Andreas; Bruelheide, Helge; Durka, Walter; Michalski, Stefan G; Purschke, Oliver; Assmann, Thorsten

    2014-02-01

    The effects of species loss on ecosystems depend on the community's functional diversity (FD). However, how FD responds to environmental changes is poorly understood. This applies particularly to higher trophic levels, which regulate many ecosystem processes and are strongly affected by human-induced environmental changes. We analyzed how functional richness (FRic), evenness (FEve), and divergence (FDiv) of important generalist predators-epigeic spiders-are affected by changes in woody plant species richness, plant phylogenetic diversity, and stand age in highly diverse subtropical forests in China. FEve and FDiv of spiders increased with plant richness and stand age. FRic remained on a constant level despite decreasing spider species richness with increasing plant species richness. Plant phylogenetic diversity had no consistent effect on spider FD. The results contrast with the negative effect of diversity on spider species richness and suggest that functional redundancy among spiders decreased with increasing plant richness through non-random species loss. Moreover, increasing functional dissimilarity within spider assemblages with increasing plant richness indicates that the abundance distribution of predators in functional trait space affects ecological functions independent of predator species richness or the available trait space. While plant diversity is generally hypothesized to positively affect predators, our results only support this hypothesis for FD-and here particularly for trait distributions within the overall functional trait space-and not for patterns in species richness. Understanding the way predator assemblages affect ecosystem functions in such highly diverse, natural ecosystems thus requires explicit consideration of FD and its relationship with species richness.

  14. Foraging modality and plasticity in foraging traits determine the strength of competitive interactions among carnivorous plants, spiders and toads.

    PubMed

    Jennings, David E; Krupa, James J; Rohr, Jason R

    2016-07-01

    Foraging modalities (e.g. passive, sit-and-wait, active) and traits are plastic in some species, but the extent to which this plasticity affects interspecific competition remains unclear. Using a long-term laboratory mesocosm experiment, we quantified competition strength and the plasticity of foraging traits in a guild of generalist predators of arthropods with a range of foraging modalities. Each mesocosm contained eight passively foraging pink sundews, and we employed an experimental design where treatments were the presence or absence of a sit-and-wait foraging spider and actively foraging toad crossed with five levels of prey abundance. We hypothesized that actively foraging toads would outcompete the other species at low prey abundance, but that spiders and sundews would exhibit plasticity in foraging traits to compensate for strong competition when prey were limited. Results generally supported our hypotheses. Toads had a greater effect on sundews at low prey abundances, and toad presence caused spiders to locate webs higher above the ground. Additionally, the closer large spider webs were to the ground, the greater the trichome densities produced by sundews. Also, spider webs were larger with than without toads and as sundew numbers increased, and these effects were more prominent as resources became limited. Finally, spiders negatively affected toad growth only at low prey abundance. These findings highlight the long-term importance of foraging modality and plasticity of foraging traits in determining the strength of competition within and across taxonomic kingdoms. Future research should assess whether plasticity in foraging traits helps to maintain coexistence within this guild and whether foraging modality can be used as a trait to reliably predict the strength of competitive interactions.

  15. Bioprospecting Finds the Toughest Biological Material: Extraordinary Silk from a Giant Riverine Orb Spider

    PubMed Central

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

    2010-01-01

    Background Combining high strength and elasticity, spider silks are exceptionally tough, i.e., able to absorb massive kinetic energy before breaking. Spider silk is therefore a model polymer for development of high performance biomimetic fibers. There are over 41.000 described species of spiders, most spinning multiple types of silk. Thus we have available some 200.000+ unique silks that may cover an amazing breadth of material properties. To date, however, silks from only a few tens of species have been characterized, most chosen haphazardly as model organisms (Nephila) or simply from researchers' backyards. Are we limited to ‘blindly fishing’ in efforts to discover extraordinary silks? Or, could scientists use ecology to predict which species are likely to spin silks exhibiting exceptional performance properties? Methodology We examined the biomechanical properties of silk produced by the remarkable Malagasy ‘Darwin's bark spider’ (Caerostris darwini), which we predicted would produce exceptional silk based upon its amazing web. The spider constructs its giant orb web (up to 2.8 m2) suspended above streams, rivers, and lakes. It attaches the web to substrates on each riverbank by anchor threads as long as 25 meters. Dragline silk from both Caerostris webs and forcibly pulled silk, exhibits an extraordinary combination of high tensile strength and elasticity previously unknown for spider silk. The toughness of forcibly silked fibers averages 350 MJ/m3, with some samples reaching 520 MJ/m3. Thus, C. darwini silk is more than twice tougher than any previously described silk, and over 10 times better than Kevlar®. Caerostris capture spiral silk is similarly exceptionally tough. Conclusions Caerostris darwini produces the toughest known biomaterial. We hypothesize that this extraordinary toughness coevolved with the unusual ecology and web architecture of these spiders, decreasing the likelihood of bridgelines breaking and collapsing the web into the river

  16. Mygalomorph Spider Community of a Natural Reserve in a Hilly System in Central Argentina

    PubMed Central

    Ferretti, Nelson; Pompozzi, Gabriel; Copperi, Sofia; Pérez-Miles, Fernando; González, Alda

    2012-01-01

    The diversity, abundance, spatial distribution, and phenology of the mygalomorph spider community in the “Ernesto Tornquist” Strict Nature Reserve were analyzed in this study. Located in southwestern Buenos Aires, Argentina, the Reserve is representative of the Ventania system, which is a sigmoidal mountain belt 180 km in length. This exceptional hilly ecosystem is home for many endemic species and rich native fauna and flora. Spider abundance was sampled monthly from October 2009 to October 2010 by hand capture and pitfall traps on grassland slopes. The species recorded in the study area were: Actinopus sp.1 (Actinopodidae); Grammostola vachoni and Plesiopelma longisternale (Theraphosidae); Acanthogonatus centralis (Nemesiidae); and Mecicobothrium thorelli (Mecicobothriidae). Grammostola vachoni and Acanthogonatus centralis were the dominant species in hand capture and pitfall traps, respectively. The seasonal variation, diversity, and abundance of the mygalomorph community are analyzed and discussed here. The Mygalomorphae of the Ventania system comprises an important group of sedentary and cryptozoic spiders that seem to be highly dependent on habitat type and environmental factors. PMID:22947032

  17. Molecular phylogeny and biogeography of an ancient Holarctic lineage of mygalomorph spiders (Araneae: Antrodiaetidae: Antrodiaetus).

    PubMed

    Hendrixson, Brent E; Bond, Jason E

    2007-03-01

    The mygalomorph spider genera Antrodiaetus and Atypoides (Antrodiaetidae) belong to an ancient lineage that has persisted since at least the Cretaceous. These spiders display a classic disjunct Holarctic distribution with species in the eastern Palaearctic plus the western and eastern Nearctic. Prior phylogenetic analyses of this group have been proposed on the basis of morphology, but lack strong support and independent corroboration. Here we present the first phylogenetic analysis of species-level relationships based on molecular data obtained from the mitochondrial (cytochrome c oxidase subunit I) and nuclear (18S and 28S rRNA) genomes. Analyses corroborate earlier findings that Atypoides forms a paraphyletic grade with respect to Antrodiaetus, and consequently, that genus is formally synonymized under Antrodiaetus. In addition, our results support the relatively early divergence of Antrodiaetus roretzi. Antrodiaetus pacificus is "paraphyletic" with respect to the A. lincolnianus group and is likely an assemblage of numerous species. The final topology based on a combined molecular dataset, in conjunction with two different molecular dating techniques (penalized likelihood plus a Bayesian approach) and ancestral distribution reconstructions, was used to infer the historical biogeography of these spiders. Trans-Beringian and trans-Atlantic routes appear to account for the present-day distribution of Antrodiaetus in Japan and North America. Future studies on Antrodiaetus phylogeny will be used to address questions regarding morphological stasis and the evolution of quantitative morphological characters.

  18. Mygalomorph spider community of a natural reserve in a hilly system in central Argentina.

    PubMed

    Ferretti, Nelson; Pompozzi, Gabriel; Copperi, Sofia; Pérez-Miles, Fernando; González, Alda

    2012-01-01

    The diversity, abundance, spatial distribution, and phenology of the mygalomorph spider community in the "Ernesto Tornquist" Strict Nature Reserve were analyzed in this study. Located in southwestern Buenos Aires, Argentina, the Reserve is representative of the Ventania system, which is a sigmoidal mountain belt 180 km in length. This exceptional hilly ecosystem is home for many endemic species and rich native fauna and flora. Spider abundance was sampled monthly from October 2009 to October 2010 by hand capture and pitfall traps on grassland slopes. The species recorded in the study area were: Actinopus sp.1 (Actinopodidae); Grammostola vachoni and Plesiopelma longisternale (Theraphosidae); Acanthogonatus centralis (Nemesiidae); and Mecicobothrium thorelli (Mecicobothriidae). Grammostola vachoni and Acanthogonatus centralis were the dominant species in hand capture and pitfall traps, respectively. The seasonal variation, diversity, and abundance of the mygalomorph community are analyzed and discussed here. The Mygalomorphae of the Ventania system comprises an important group of sedentary and cryptozoic spiders that seem to be highly dependent on habitat type and environmental factors.

  19. Spider Bite: A Rare Case of Acute Necrotic Arachnidism with Rapid and Fatal Evolution

    PubMed Central

    Giglio, Anna Maria; Scozzafava, Annamaria; Filippelli, Orazio; Serafino, Giuseppe; Verre, Mario

    2016-01-01

    The spider bites are quite frequent and often resolve quickly without leaving outcomes; only some species are capable of causing necrotic and systematic lesions in humans. Among them, we should mention the genus Loxosceles. The venom released from the spider bite of Loxosceles species is composed of proteins, enzymes, and nonenzymatic polypeptides. The phospholipase D family was identified as the active component of the venom. This family of enzymes is responsible for the local and systemic effects observed in loxoscelism. Phospholipases D interact with cell membranes triggering alterations which involve the complement system and activation of neutrophils and they cause the dermonecrotic skin lesions and systemic effects. We describe a fatal case of acute intoxication caused by a spider bite probably belonging to the species Loxosceles. The initial lesion was localized to a finger of a hand. Clinical course was worsening with deep necrotic lesions on limb, shock, hemolysis, acute kidney failure, and disseminated intravascular coagulation. All therapies were ineffective. This is the first fatal case described in Europe. PMID:27651958

  20. [Population dynamics of ground carabid beetles and spiders in a wheat field along the wheat-alfalfa interface and their response to alfalfa mowing].

    PubMed

    Liu, Wen-Hui; Hu, Yi-Jun; Hu, Wen-Chao; Hong, Bo; Guan, Xiao-Qing; Ma, Shi-Yu; He, Da-Han

    2014-09-01

    Taking the wheat-alfalfa and wheat-wheat interfaces as model systems, sampling points were set by the method of pitfall trapping in the wheat field at the distances of 3 m, 6 m, 9 m, 12 m, 15 m, 18 m, 21 m, 24 m, and 27 m from the interface. The species composition and abundance of ground carabid beetles and spiders captured in pitfalls were investigated. The results showed that, to some extent there was an edge effect on species diversity and abundance of ground carabid beetles and spiders along the two interfaces. A marked edge effect was observed between 15 m and 18 m along the alfalfa-wheat interface, while no edge effect was found at a distance over 20 m. The edge effect along the wheat-wheat interface was weaker in comparison to the alfalfa-wheat interface. Alfalfa mowing resulted in the migration of a large number of ground carabid beetles and spiders to the adjacent wheat filed. During ten days since mowing, both species and abundance of ground carabid beetles and spiders increased in wheat filed within the distance of 20 m along the alfalfa-wheat interface. The spatial distribution of species diversity of ground beetles and spiders, together with the population abundance of the dominant Chlaenius pallipes and Pardosa astrigera, were depicted, which could directly indicate the migrating process of natural enemy from alfalfa to wheat field.

  1. Are You as Clever as a Spider?

    ERIC Educational Resources Information Center

    Beck, Charles R.

    1992-01-01

    A hands-on simulation on spider web construction is described. Students recreate the mysteries of web construction by creating a yarn web with a pentagonal frame, 12 spokes, and 12 spiral loops. Contains instructions to the teacher for constructing the web board. Provides a procedure for the students to follow. (PR)

  2. Dreamcatcher, Gatekeeper, Spider Web, Safety Net.

    ERIC Educational Resources Information Center

    Tweedie, Sanford; Madden, Marjorie

    1998-01-01

    Replicates, using diverse quotations grouped under four metaphors (dreamcatcher, gatekeeper, spider web, safety net) representing the dissonance of the reading/writing processes as they might be experienced by basic skills readers. Questions the relationship of basic skills to its students; implements D. Bartholomae's recommendations to reform of…

  3. Silk Spinning in Silkworms and Spiders

    PubMed Central

    Andersson, Marlene; Johansson, Jan; Rising, Anna

    2016-01-01

    Spiders and silkworms spin silks that outcompete the toughness of all natural and manmade fibers. Herein, we compare and contrast the spinning of silk in silkworms and spiders, with the aim of identifying features that are important for fiber formation. Although spiders and silkworms are very distantly related, some features of spinning silk seem to be universal. Both spiders and silkworms produce large silk proteins that are highly repetitive and extremely soluble at high pH, likely due to the globular terminal domains that flank an intermediate repetitive region. The silk proteins are produced and stored at a very high concentration in glands, and then transported along a narrowing tube in which they change conformation in response primarily to a pH gradient generated by carbonic anhydrase and proton pumps, as well as to ions and shear forces. The silk proteins thereby convert from random coil and alpha helical soluble conformations to beta sheet fibers. We suggest that factors that need to be optimized for successful production of artificial silk proteins capable of forming tough fibers include protein solubility, pH sensitivity, and preservation of natively folded proteins throughout the purification and initial spinning processes. PMID:27517908

  4. Hey! A Brown Recluse Spider Bit Me!

    MedlinePlus

    ... putting them on. Reviewed by: Elana Pearl Ben-Joseph, MD Date reviewed: September 2016 For Teens For Kids For Parents MORE ON THIS TOPIC Hey! A Fire Ant Stung Me! Hey! A Tarantula Bit Me! Hey! A Scorpion Stung Me! Hey! A Black Widow Spider Bit Me! Contact Us Print Resources ...

  5. Effect of phenology on agonistic competitive interactions between invasive and native sheet-web spiders

    USGS Publications Warehouse

    Houser, Jeremy D.; Porter, Adam H.; Ginsberg, Howard; Jakob, Elizabeth M.

    2016-01-01

    The phenologies of introduced relative to native species can greatly influence the degree and symmetry of competition between them. The European spider Linyphia triangularis (Clerck, 1757) (Linyphiidae) reaches very high densities in coastal Maine (USA). Previous studies suggest thatL. triangularis negatively affects native linyphiid species, with competition for webs as one mechanism. We documented phenological differences between L. triangularis and three native species that illustrate the potential for the reversal of size-based competitive advantage over the course of the year. To test whether relative size influences interaction outcome, we allowed a resident spider to build a web and then introduced an intruder. We examined whether the outcomes of agonistic interactions over the webs were influenced by the species of the resident (invasive or native), the relative size of the contestants, and the species × size interaction. We found that the importance of relative size differed among species. In interactions between L. triangularis and each of two native species, size played a greater role than resident species on the outcome of interactions, suggesting that competitive advantage reverses over the season based on phenology-related size differences. Linyphia triangularis had a negative impact on the third species regardless of relative size.

  6. Restriction fragment length polymorphism catalog for molecular identification of Japanese Tetranychus spider mites (Acari: Tetranychidae).

    PubMed

    Osakabe, Masahiro; Kotsubo, Yu; Tajima, Ryusen; Hinomoto, Norihide

    2008-08-01

    Species identification is a basic issue in biosecurity. Polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) is a useful molecular diagnostic tool for species identification. However, the lack of transferability of data has been a serious shortcoming of this method. A RFLP catalog, i.e., a graph of PCR-RFLP patterns expected from sequence data, was devised as a tool to facilitate PCR-RFLP data sharing among laboratories. Twelve species of Tetranychus spider mites have been recorded in Japan to date. In this study, we analyzed DNA sequences of the internal transcribed spacer (ITS) region in nuclear ribosomal DNA of 11 Tetranychus species. For the species identification using PCR-RFLP, we chose six candidates from 131 restriction endonucleases and developed an RFLP catalog of all known Japanese Tetranychus species except Tetranychus neocaledonicus André. The RFLP catalog revealed that most Tetranychus species had diagnostic restriction fragments. The RFLP catalog is transferable and simple molecular diagnostic tool, and it has the ability to add more species and newly found intraspecific variations. Therefore, we believe that the RFLP catalog will contribute to biosecurity as a practical diagnostic tool for species identification of spider mites.

  7. Climate change and sexual size dimorphism in an Arctic spider.

    PubMed

    Høye, Toke Thomas; Hammel, Jörg U; Fuchs, Thomas; Toft, Søren

    2009-08-23

    Climate change is advancing the onset of the growing season and this is happening at a particularly fast rate in the High Arctic. However, in most species the relative fitness implications for males and females remain elusive. Here, we present data on 10 successive cohorts of the wolf spider Pardosa glacialis from Zackenberg in High-Arctic, northeast Greenland. We found marked inter-annual variation in adult body size (carapace width) and this variation was greater in females than in males. Earlier snowmelt during both years of its biennial maturation resulted in larger adult body sizes and a skew towards positive sexual size dimorphism (females bigger than males). These results illustrate the pervasive influence of climate on key life-history traits and indicate that male and female responses to climate should be investigated separately whenever possible.

  8. Total X-Ray Scattering of Spider Dragline Silk

    NASA Astrophysics Data System (ADS)

    Benmore, C. J.; Izdebski, T.; Yarger, J. L.

    2012-04-01

    Total x-ray scattering measurements of spider dragline silk fibers from Nephila clavipes, Argiope aurantia, and Latrodectus hesperus all yield similar structure factors, with only small variations between the different species. Wide-angle x-ray scattering from fibers orientated perpendicular to the beam shows a high degree of anisotropy, and differential pai