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Some ichneumonid wasps of the Polysphincta group of genera (Hymenoptera: Ichneumonidae: Pimplinae) induce behavioral modifications in their host spiders during a specific moment of their development, resulting in the construction of webs that differ in several aspects from those constructed by unparasitized individuals. In this study, we describe the parasitoid wasp Hymenoepimecis pinheirensis sp. n. (Ichneumonidae: Pimplinae) and present information on behavioral modifications in the orb-web structure of its host, the spider Leucauge volupis (Keyserling 1893). Previously, reported observation on this host/parasitoid interaction was restricted to one locality, and the wasp species was misidentified as Hymenoepimecis jordanensis Loffredo and Penteado-Dias 2009. Modified webs built by parasitized spiders lack adhesive spirals and have several radii that converge to the web hub. The cocoon built by the wasp larvae is attached to the web hub, suspended by horizontal radial lines, and surrounded by a tridimensional tangle positioned below the hub. This modified web structure is similar to the most frequent architecture of webs constructed by individuals of Leucauge mariana (Taczanowski 1881) parasitized by Hymenoepimecis tedfordi Gauld 1991. However, cocoon webs built by L. volupis parasitized by H. pinheirensis sp. n. differ from the cocoon webs described for the other Leucauge species parasitized by Hymenoepimecis wasps. This evidence suggests that the modified web pattern in Leucauge species is determined by specific responses of each spider species to the behavioral manipulation mechanism displayed by the wasps.

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Pseudogaurax Malloch is a worldwide genus of Chloropidae with 33 species in the Neotropical region and 12 occurring in Brazil. The genus is well-known for the feeding habits of its larvae which attack egg masses and larvae of several arthropods, usually breeding in the egg sacs of spiders. In this study, we expanded the distribution of P. cingulatus to northern Brazil and recorded for the first time the species preying on Tetragnatha egg sacs. In addition, diagnosis, digital images and a distribution map are provided.(AU)

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Pseudogaurax Malloch is a worldwide genus of Chloropidae with 33 species in the Neotropical region and 12 occurring in Brazil. The genus is well-known for the feeding habits of its larvae which attack egg masses and larvae of several arthropods, usually breeding in the egg sacs of spiders. In this study, we expanded the distribution of P. cingulatus to northern Brazil and recorded for the first time the species preying on Tetragnatha egg sacs. In addition, diagnosis, digital images and a distribution map are provided.

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Spiders rely on venom to catch prey and few species are even capable of capturing vertebrates. The majority of spiders are generalist predators, possessing complex venom, in which different toxins seem to target different types of prey. In this study, we focused on the trophic ecology and venom toxicity of Phoneutria boliviensis F. O. Pickard-Cambridge, 1897, a Central American spider of medical importance. We tested the hypothesis that its venom is adapted to catch vertebrate prey by studying its trophic ecology and venom toxicity against selected vertebrate and invertebrate prey. We compared both trophic ecology (based on acceptance experiments) and toxicity (based on bioassays) among sexes of this species. We found that P. boliviensis accepted geckos, spiders, and cockroaches as prey, but rejected frogs. There was no difference in acceptance between males and females. The venom of P. boliviensis was far more efficient against vertebrate (geckos) than invertebrate (spiders) prey in both immobilization time and LD50. Surprisingly, venom of males was more efficient than that of females. Our results suggest that P. boliviensis has adapted its venom to catch vertebrates, which may explain its toxicity to humans.

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Exetasis jujuyensis Gillung sp. nov. (Acroceridae) is described from Argentina and a dichotomous key to species of Exetasis Walker is provided. Detailed observations are presented on the effect of fly larval development on the behavior of the host spider (Acanthoscurria sternalis Pocock (Theraphosidae)).

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The male of Hymenoepimecis japi (Hymenoptera, Ichneumonidae, Pimplinae) is described and illustrated. The specimen was collected in a modified web (cocoon web) of Leucauge roseosignata (Araneae, Tetragnathidae) made in a laboratory. Both, host and parasitoid were collected in Reserva Biológica Serra do Japi, located in Jundiaí, São Paulo, Brazil.

O macho de Hymenoepimecis japi (Hymenoptera, Ichneumonidae, Pimplinae) é descrito e ilustrado. O espécime foi coletado em teia modificada "cocoon web" de Leucauge roseosignata (Araneae, Tetragnathidae), construída no laboratório. Ambos, hospedeiro e parasitoide, foram coletados na Reserva Biológica Serra do Japi, localizada em Jundiaí, Estado de São Paulo, Brasil.

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The wasp Hymenoepimecis silvanae Loffredo and Penteado-Dias, 2009, was recorded parasitising females of Araneus venatrix. The male of H. silvanae is described and illustrated. Specimens were collected in the Parque Estadual de Intervales and Reserva Biológica Serra do Japi, both located in the state of São Paulo, Brazil.

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The wasp Hymenoepimecis silvanae Loffredo and Penteado-Dias, 2009, was recorded parasitising females of Araneus venatrix. The male of H. silvanae is described and illustrated. Specimens were collected in the Parque Estadual de Intervales and Reserva Biológica Serra do Japi, both located in the state of São Paulo, Brazil.

A vespa Hymenoepimecis silvanae Loffredo and Penteado-Dias, 2009 foi registrada parasitando fêmeas de Araneus venatrix. O macho de H. silvanae, é descrito e ilustrado. Os espécimes foram coletados no Parque Estadual de Intervales e na Reserva Biológica Serra do Japi, ambos localizados no Estado de São Paulo, Brasil.

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The male of Hymenoepimecis japi (Hymenoptera, Ichneumonidae, Pimplinae) is described and illustrated. The specimen was collected in a modified web (cocoon web) of Leucauge roseosignata (Araneae, Tetragnathidae) made in a laboratory. Both, host and parasitoid were collected in Reserva Biológica Serra do Japi, located in Jundiaí, São Paulo, Brazil.

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The rates of parasitism of Theridion evexum by the parasitoid wasp Zatypota petronae, and Allocyclosa bifurca by Polysphincta gutfreundi, were followed for two years. Parasitism of T. evexum was very low (mean 1.39+1.8%), and restricted to nearly seven months of the year. Parasitism of A. bifurca was higher (mean 7.8+7.6%), and did not show a seasonal pattern. Reproduction of the host spider T. evexum was highly seasonal, with only one, highly coordinated generation per year, while adults of A. bifurca were present year round. Short-term autocorrelation on parasitism rates over time at different sites suggest that P. gutfreundi tend to return to the same sites to hunt hosts over periods of a few weeks. Rev. Biol. Trop. 56 (2): 749-754. Epub 2008 June 30.

Las tasas de parasitismo de Theridion evexum por la avispa parasitoide Zatypota petronae y de Allocyclosa bifurca por Polysphincta gutfreundi fueron estudiadas durante dos años. El parasitismo en T. evexum fue muy bajo (promedio 1.39+1.8%) y restringido a aproximadamente siete meses del año. El parasitismo en A. bifurca fue más alto (promedio 7.8+7.6%) y no mostró un claro patrón estacional. La reproducción de la araña hospedera T. evexum fue muy estacional, con solamente una generación por año, mientras que los adultos de A. bifurca estuvieron presentes todo el año. Autocorrelaciones de las tasas de parasitismo entre censos consecutivos en diferentes sitios sugiere que P. gutfreundi tiende a retornar a los mismos sitios para parasitar las arañas hospederas durante algunas semanas.

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The rates of parasitism of Theridion evexum by the parasitoid wasp Zatypota petronae, and Allocyclosa bifurca by Polysphincta gutfreundi, were followed for two years. Parasitism of T. evexum was very low (mean 1.39 +/- 1.8%), and restricted to nearly seven months of the year. Parasitism of A. bifurca was higher (mean 7.8 +/- 7.6%), and did not show a seasonal pattern. Reproduction of the host spider T evexum was highly seasonal, with only one, highly coordinated generation per year, while adults of A. bifurca were present year round. Short-term autocorrelation on parasitism rates over time at different sites suggest that P. gutfreundi tend to return to the same sites to hunt hosts over periods of a few weeks.

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All species included in the Polysphincta genus-group develop as ectophagous parasitoids of active spiders, killing their hosts prior to pupation. However, little information regarding natural history and ovipositing behavior of most species are available. In this study we inspected 85 webs of Araneus omnicolor to evaluate the frequency of parasitism and host size preferences of the wasp Hymenoepimecis sp. We also described the web characteristics of normal and parasitized spiders and the wasp ovipositing behavior. About 41% of the adult females of A. omnicolor inspected were parasitized. The highest incidence of parasitism was observed among relatively small females while no egg or larva was found in large individuals. Araneus omnicolor builds a strong web composed of an orb and barrier threads, where the spider rests within a curled leaf. The parasitoid larva builds its cocoon within this refuge, and modified cocoon webs were not observed. The ovipositing behavior of Hymenoepimecis sp. was very similar to that of Hymenoepimecis argyraphaga parasitizing Leucauge argyra, including the position of the sting, the killing of a previously attached larva, and the expelling of the egg from the base of the ovipositor.

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