The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Kent M Daane - One of the best experts on this subject based on the ideXlab platform.
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ecosystem services in the face of invasion the persistence of native and nonnative spiders in an agricultural landscape
Ecological Applications, 2011Co-Authors: Brian N. Hogg, Kent M DaaneAbstract: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.
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Regional patterns in the invasion success of Cheiracanthium spiders (Miturgidae) in vineyard ecosystems
Biological Invasions, 2010Co-Authors: Brian N. Hogg, Rosemary G. Gillespie, Kent M DaaneAbstract:Invasions have often been linked to reduced biodiversity, but the role of non-native species in the decline of native species is ambiguous. In a 2003 survey of four California vineyard regions, exotic spiders ( Cheiracanthium spp.) were more dominant in vineyards with lower spider species diversity and reduced spider abundance. There was no evidence for the role of species interactions in the invasion of Cheiracanthium spiders, however, as native spiders from the same feeding guild were most abundant in regions with high Cheiracanthium levels. Comparison with a survey conducted 10 years earlier indicated that the recent invader C. mildei simply represented an addition to the spider community, with no apparent change in proportions of the congener C. inclusum . Invasion success is discussed with respect to agricultural habitat, as results suggest that disturbed conditions in many vineyards may favor Cheiracanthium spp. and native wandering spiders while decreasing overall spider diversity.
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spider and leafhopper erythroneura spp response to vineyard ground cover
Environmental Entomology, 2003Co-Authors: Michael J Costello, Kent M DaaneAbstract:Ground cover is used in some vineyards to improve soil structure and help manage insect pests; previous studies have shown lower leafhopper (Erythroneura spp.) densities on vines grown with ground cover. We undertook a 2-yr study to determine why ground cover is associated with reduced leafhopper densities. Ground cover consisted of a fall-planted cover crop of purple vetch (Vicia benghalensis) and barley (Hordeum vulgare), which senesced in May and was replaced by a complex of resident vegetation comprised primarily of the grasses Echinochloa spp., Digitaria sanguinalis, and Setaria spp., as well as common knotweed (Polygonum aviculare). We compared three treatments during the growing season: Cover, No Cover, and Cover/Exclusion. Cover/Exclusion was similar to Cover treatment but with barriers to impede arthropod movement between ground cover and vines. We measured leafhopper density and egg parasitism, spider density and diversity, and grapevine vigor, and found that mid- and late-season leafhopper densities were significantly lower in Cover versus No Cover. Neither leafhopper egg parasitism nor spider density on the vines or ground cover could explain these differences; however, grapevine vigor was significantly lower in Cover than No Cover, and provides the best correlation to leafhopper density. Late-season leafhopper density was highest in the Exclusion treatment but cannot be explained by changes in grapevine vigor. Individual spider species composition and density on the grapevine canopy varied significantly among treatments: Trachelas pacificus (Chamberlin and Ivie) was higher in the Cover treatment, Hololena nedra Chamberlin and Ivie, Cheiracanthium inclusum (Hentz), and Neoscona oaxacensis (Keyserling) were lower in the Exclusion treatment, and Oxyopes spp. was higher in the Exclusion treatment. We suggest the lower densities of leafhoppers in the Cover treatment resulted from poorer host plant quality because of the competition between ground cover and grapevines. The higher late-season leafhopper densities in the Exclusion treatment may be due to changes in spider species composition, and subsequently, differences in rates of predation on leafhopper nymphs.
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spider and leafhopper erythroneura spp response to vineyard ground cover
Environmental Entomology, 2003Co-Authors: Michael J Costello, Kent M DaaneAbstract:Ground cover is used in some vineyards to improve soil structure and help manage insect pests; previous studies have shown lower leafhopper (Erythroneura spp.) densities on vines grown with ground cover. We undertook a 2-yr study to determine why ground cover is associated with reduced leafhopper densities. Ground cover consisted of a fall-planted cover crop of purple vetch (Vicia benghalensis) and barley (Hordeum vulgare), which senesced in May and was replaced by a complex of resident vegetation comprised primarily of the grasses Echinochloa spp., Digitaria sanguinalis, and Setaria spp., as well as common knotweed (Polygonum aviculare). We compared three treatments during the growing season: Cover, No Cover, and Cover/Exclusion. Cover/Exclusion was similar to Cover treatment but with barriers to impede arthropod movement between ground cover and vines. We measured leafhopper density and egg parasitism, spider density and diversity, and grapevine vigor, and found that mid- and late-season leafhopper densities were significantly lower in Cover versus No Cover. Neither leafhopper egg parasitism nor spider density on the vines or ground cover could explain these differences; however, grapevine vigor was significantly lower in Cover than No Cover, and provides the best correlation to leafhopper density. Late-season leafhopper density was highest in the Exclusion treatment but cannot be explained by changes in grapevine vigor. Individual spider species composition and density on the grapevine canopy varied significantly among treatments: Trachelas pacificus (Chamberlin and Ivie) was higher in the Cover treatment, Hololena nedra Chamberlin and Ivie, Cheiracanthium inclusum (Hentz), and Neoscona oaxacensis (Keyserling) were lower in the Exclusion treatment, and Oxyopes spp. was higher in the Exclusion treatment. We suggest the lower densities of leafhoppers in the Cover treatment resulted from poorer host plant quality because of the competition between ground cover and grapevines. The higher late-season leafhopper densities in the Exclusion treatment may be due to changes in spider species composition, and subsequently, differences in rates of predation on leafhopper nymphs.
Alessandro Ceschi - One of the best experts on this subject based on the ideXlab platform.
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a two year study of verified spider bites in switzerland and a review of the european spider bite literature
Toxicon, 2013Co-Authors: Wolfgang Nentwig, Markus Gnadinger, Joan Fuchs, Alessandro CeschiAbstract: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.
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a two year study of verified spider bites in switzerland and a review of the european spider bite literature
Toxicon, 2013Co-Authors: Wolfgang Nentwig, Markus Gnadinger, Joan Fuchs, Alessandro CeschiAbstract: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.
Wolfgang Nentwig - One of the best experts on this subject based on the ideXlab platform.
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a two year study of verified spider bites in switzerland and a review of the european spider bite literature
Toxicon, 2013Co-Authors: Wolfgang Nentwig, Markus Gnadinger, Joan Fuchs, Alessandro CeschiAbstract: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.
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a two year study of verified spider bites in switzerland and a review of the european spider bite literature
Toxicon, 2013Co-Authors: Wolfgang Nentwig, Markus Gnadinger, Joan Fuchs, Alessandro CeschiAbstract: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.
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multicomponent venom of the spider cupiennius salei a bioanalytical investigation applying different strategies
FEBS Journal, 2012Co-Authors: Christian Trachsel, Wolfgang Nentwig, Doreen Siegemund, Urs Kampfer, Lukas S Kopp, Claudia Buhr, Jonas Grossmann, Christoph Luthi, Monica Cunningham, Lucia KuhnnentwigAbstract:The multicomponent venom of the spider Cupiennius salei was separated by three different chromatographic strategies to facilitate subsequent analysis of peptidic venom components by tandem mass spectrometry (MALDI-TOF-MS and ESI-MS), Edman degradation and amino acid analysis: (a) desalting of the crude venom by RP-HPLC only, (b) chromatographic separation of the crude venom into 42 fractions by RP-HPLC, and (c) multidimensional purification of the crude venom by size exclusion and cation exchange chromatography and RP-HPLC. A total of 286 components were identified in the venom of C. salei by mass spectrometry and the sequence of 49 new peptides was determined de novo by Edman degradation and tandem mass spectrometry; 30 were C-terminally amidated. The novel peptides were assigned to two main groups: (a) short cationic peptides and (b) Cys-containing peptides with the inhibitor cystine knot motif. Bioinformatics revealed a limited number of substantial similarities, namely with the peptides CpTx1 from the spider Cheiracantium punctorium and U3-ctenitoxin-Asp1a from the South American fishing spider (Ancylometes sp.) and with sequences from a Lycosa singoriensis venom gland transcriptome analysis. The results clearly indicate that the quality of the data is strongly dependent on the chosen separation strategy. The combination of orthogonal analytical methods efficiently excludes alkali ion and matrix adducts, provides indispensable information for an unambiguous identification of isomasses, and results in the most comprehensive repertoire of peptides identified in the venom of C. salei so far.
Alexander A. Vassilevski - One of the best experts on this subject based on the ideXlab platform.
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structure of the yellow sac spider Cheiracanthium punctorium genes provides clues to evolution of insecticidal two domain knottin toxins
Insect Molecular Biology, 2014Co-Authors: Maria Y Sachkova, Eugene V Grishin, Anna A Slavokhotova, Alexander A. VassilevskiAbstract:Yellow sac spiders (Cheiracanthium punctorium, family Miturgidae) are unique in terms of venom composition, because, as we show here, two-domain toxins have replaced the usual one-domain peptides as the major constituents. We report the structure of the two-domain Che. punctorium toxins (CpTx), along with the corresponding cDNA and genomic DNA sequences. At least three groups of insecticidal CpTx were identified, each consisting of several members. Unlike many cone snail and snake toxins, accelerated evolution is not typical of cptx genes, which instead appear to be under the pressure of purifying selection. Both CpTx modules present the inhibitor cystine knot (ICK), or knottin signature; however, the sequence similarity between the domains is low. Conversely, notable similarity was found between separate domains of CpTx and one-domain toxins from spiders of the Lycosidae family. The observed chimerism is a landmark of exon shuffling events, but in contrast to many families of multidomain protein genes no introns were found in the cptx genes. Considering the possible scenarios, we suggest that an early transcription-mediated fusion event between two related one-domain toxin genes led to the emergence of a primordial cptx-like sequence. We conclude that evolution of toxin variability in spiders appears to be quite different from other venomous animals.
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Novel Class of Spider Toxin: ACTIVE PRINCIPLE FROM THE YELLOW SAC SPIDER Cheiracanthium PUNCTORIUM VENOM IS A UNIQUE TWO-DOMAIN POLYPEPTIDE*
Journal of Biological Chemistry, 2010Co-Authors: Alexander A. Vassilevski, Irina M. Fedorova, Ekaterina E. Maleeva, Olga V. Samsonova, Yuliya V Korolkova, Svetlana S. Efimova, Ludmila V. Schagina, L. G. Magazanik, Alexei V Feofanov, Eugene V GrishinAbstract: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.
Eugene V Grishin - One of the best experts on this subject based on the ideXlab platform.
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structure of the yellow sac spider Cheiracanthium punctorium genes provides clues to evolution of insecticidal two domain knottin toxins
Insect Molecular Biology, 2014Co-Authors: Maria Y Sachkova, Eugene V Grishin, Anna A Slavokhotova, Alexander A. VassilevskiAbstract:Yellow sac spiders (Cheiracanthium punctorium, family Miturgidae) are unique in terms of venom composition, because, as we show here, two-domain toxins have replaced the usual one-domain peptides as the major constituents. We report the structure of the two-domain Che. punctorium toxins (CpTx), along with the corresponding cDNA and genomic DNA sequences. At least three groups of insecticidal CpTx were identified, each consisting of several members. Unlike many cone snail and snake toxins, accelerated evolution is not typical of cptx genes, which instead appear to be under the pressure of purifying selection. Both CpTx modules present the inhibitor cystine knot (ICK), or knottin signature; however, the sequence similarity between the domains is low. Conversely, notable similarity was found between separate domains of CpTx and one-domain toxins from spiders of the Lycosidae family. The observed chimerism is a landmark of exon shuffling events, but in contrast to many families of multidomain protein genes no introns were found in the cptx genes. Considering the possible scenarios, we suggest that an early transcription-mediated fusion event between two related one-domain toxin genes led to the emergence of a primordial cptx-like sequence. We conclude that evolution of toxin variability in spiders appears to be quite different from other venomous animals.
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Novel Class of Spider Toxin: ACTIVE PRINCIPLE FROM THE YELLOW SAC SPIDER Cheiracanthium PUNCTORIUM VENOM IS A UNIQUE TWO-DOMAIN POLYPEPTIDE*
Journal of Biological Chemistry, 2010Co-Authors: Alexander A. Vassilevski, Irina M. Fedorova, Ekaterina E. Maleeva, Olga V. Samsonova, Yuliya V Korolkova, Svetlana S. Efimova, Ludmila V. Schagina, L. G. Magazanik, Alexei V Feofanov, Eugene V GrishinAbstract: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.