Strategic pheromone signalling by mate searching females of the sexually cannibalistic spider Argiope bruennichi.

Reproduction often requires finding a mating partner. To this end, females of many arthropods advertise their presence to searching males via volatile chemical signals. Such pheromones are considered low-cost signals, although this notion is based on little evidence and has recently been challenged. Even when using comparatively low-cost signals, females should signal as little as possible to minimize costs while still ensuring mate attraction. Here, we test the strategic-signalling hypothesis using Argiope bruennichi. In this orb-weaving spider, egg maturation commences with adult moult, and females that do not attract a male in time will lay a large batch of unfertilized eggs approximately three weeks after maturation. Using GC-MS analyses, we show that virgin females enhance their signalling effort, i.e. pheromone quantity per unit body mass, with increasing age and approaching oviposition. We further demonstrate that pheromone release is condition dependent, suggesting the occurrence of physiological costs. Mate choice assays revealed that pheromone quantity is the only predictor of female attractiveness for males. In support of the strategic-signalling hypothesis, pheromone signals by female A. bruennichi become stronger with increased need as well as body condition, and might thus qualify as an honest signal of female quality.

Biodiversity of orb-web spiders (family: araneidae) of buner valley, Pakistan / Biodiversidade de aranhas construtoras de teia (família: araneidae) do vale buner, Paquistão

The present research was carried out to explore the spider fauna of Buner valley with taxonomic study from February 2018 to January 2019. For this purpose samples were collected, four times at each month from 4 tehsils: Daggar, Gagra, Mandan and Totalai. Two methods were used, hand picking and sweep net for collection of samples. During day and night, three habitats, arid area, agriculture land and building area were search for collection. A total of 534 samples of spider were collected from four sampling sites, in which 379 were belonging to family Araniedae. After confirmation, the identified species were belonging to 8 genera (Neoscona, Argiope, Cyclosa, Araneus, Cyrtophora, Larinia, Erivoxia and Poltys) and 19 species. 18 of them were identified to specie level while a single specie to its generic level. The genus Neoscona was the dominant genus 26.31% having 5 species while the genus Argiope 21.05% is the second dominant having 4 species followed by Cyclosa 15.78% having 3 species followed by Cyrtophora and Araneus 10.52% having two species both. The Poltys and Larinia 5.26% are the rarest genera represent single-single specie both. Statistical analysis show that specie richness (D) = 5.77, Simpson index (1-D) = 0.87, Shannon index (H) = 2.33. Diversity of spiders was evenly distributed and calculated Evenness value was H/InS = 0.5408. There is also few atypical species and Fisher alpha estimate high value (Fisher α) = 4.42. Chao-1 estimated we have reported 22 species.

A presente pesquisa foi realizada para explorar a fauna de aranhas do vale Buner, em um estudo taxonômico realizado de fevereiro de 2018 a janeiro de 2019. Para esse fim, foram coletadas amostras, quatro vezes por mês, a partir de 4 subdistritos: Daggar, Gagra, Mandan e Totalai. Foram utilizados dois métodos, coleta manual e rede de varredura, para a obtenção das amostras. Durante o dia e a noite, foram pesquisados três habitats: área árida, área agrícola e área de construção. Foram coletadas 534 amostras de aranha em quatro locais de amostragem, sendo que 379 pertenciam à família Araneidae. Após a confirmação, as espécies identificadas pertenciam a 8 gêneros (Neoscona, Argiope, Cyclosa, Araneus, Cyrtophora, Larinia, Erivoxia e Poltys) e a 19 espécies (18 delas foram identificados em seu nível de espécie, enquanto uma única foi identificada em seu nível genérico). O gênero Neoscona foi dominante (26,31%), com 5 espécies, seguido pelos gêneros Argiope (21,05%), com 4 espécies, Cyclosa (15,78%), com 3 espécies, e Cyrtophora e Araneus (10,52%), com 2 espécies. Poltys e Larinia (5,26%) são os gêneros mais raros, representando a mesma espécie. A análise estatística mostrou que a riqueza de espécies (D) foi de 5,77, o índice de Simpson (1-D) foi de 0,87 e o índice de Shannon (H) foi de 2,33. A diversidade de aranhas foi distribuída uniformemente, e o valor calculado da uniformidade foi H / InS = 0,5408. Também existem poucas espécies atípicas, e o alfa de Fisher (Fisher α) estimou o valor de 4,42. Já Chao-1 estimou 22 espécies.

Biodiversity of orb-web spiders (family: araneidae) of buner valley, Pakistan

Abstract The present research was carried out to explore the spider fauna of Buner valley with taxonomic study from February 2018 to January 2019. For this purpose samples were collected, four times at each month from 4 tehsils: Daggar, Gagra, Mandan and Totalai. Two methods were used, hand picking and sweep net for collection of samples. During day and night, three habitats, arid area, agriculture land and building area were search for collection. A total of 534 samples of spider were collected from four sampling sites, in which 379 were belonging to family Araniedae. After confirmation, the identified species were belonging to 8 genera (Neoscona, Argiope, Cyclosa, Araneus, Cyrtophora, Larinia, Erivoxia and Poltys) and 19 species. 18 of them were identified to specie level while a single specie to its generic level. The genus Neoscona was the dominant genus 26.31% having 5 species while the genus Argiope 21.05% is the second dominant having 4 species followed by Cyclosa 15.78% having 3 species followed by Cyrtophora and Araneus 10.52% having two species both. The Poltys and Larinia 5.26% are the rarest genera represent single-single specie both. Statistical analysis show that specie richness (D) = 5.77, Simpson index (1-D) = 0.87, Shannon index (H) = 2.33. Diversity of spiders was evenly distributed and calculated Evenness value was H/InS = 0.5408. There is also few atypical species and Fisher alpha estimate high value (Fisher ) = 4.42. Chao-1 estimated we have reported 22 species.

Resumo A presente pesquisa foi realizada para explorar a fauna de aranhas do vale Buner, em um estudo taxonômico realizado de fevereiro de 2018 a janeiro de 2019. Para esse fim, foram coletadas amostras, quatro vezes por mês, a partir de 4 subdistritos: Daggar, Gagra, Mandan e Totalai. Foram utilizados dois métodos, coleta manual e rede de varredura, para a obtenção das amostras. Durante o dia e a noite, foram pesquisados três habitats: área árida, área agrícola e área de construção. Foram coletadas 534 amostras de aranha em quatro locais de amostragem, sendo que 379 pertenciam à família Araneidae. Após a confirmação, as espécies identificadas pertenciam a 8 gêneros (Neoscona, Argiope, Cyclosa, Araneus, Cyrtophora, Larinia, Erivoxia e Poltys) e a 19 espécies (18 delas foram identificados em seu nível de espécie, enquanto uma única foi identificada em seu nível genérico). O gênero Neoscona foi dominante (26,31%), com 5 espécies, seguido pelos gêneros Argiope (21,05%), com 4 espécies, Cyclosa (15,78%), com 3 espécies, e Cyrtophora e Araneus (10,52%), com 2 espécies. Poltys e Larinia (5,26%) são os gêneros mais raros, representando a mesma espécie. A análise estatística mostrou que a riqueza de espécies (D) foi de 5,77, o índice de Simpson (1-D) foi de 0,87 e o índice de Shannon (H) foi de 2,33. A diversidade de aranhas foi distribuída uniformemente, e o valor calculado da uniformidade foi H / InS = 0,5408. Também existem poucas espécies atípicas, e o alfa de Fisher (Fisher ) estimou o valor de 4,42. Já Chao-1 estimou 22 espécies.

Biodiversity of orb-web spiders (family: araneidae) of buner valley, Pakistan / Biodiversidade de aranhas construtoras de teia (família: araneidae) do vale buner, Paquistão

The present research was carried out to explore the spider fauna of Buner valley with taxonomic study from February 2018 to January 2019. For this purpose samples were collected, four times at each month from 4 tehsils: Daggar, Gagra, Mandan and Totalai. Two methods were used, hand picking and sweep net for collection of samples. During day and night, three habitats, arid area, agriculture land and building area were search for collection. A total of 534 samples of spider were collected from four sampling sites, in which 379 were belonging to family Araniedae. After confirmation, the identified species were belonging to 8 genera (Neoscona, Argiope, Cyclosa, Araneus, Cyrtophora, Larinia, Erivoxia and Poltys) and 19 species. 18 of them were identified to specie level while a single specie to its generic level. The genus Neoscona was the dominant genus 26.31% having 5 species while the genus Argiope 21.05% is the second dominant having 4 species followed by Cyclosa 15.78% having 3 species followed by Cyrtophora and Araneus 10.52% having two species both. The Poltys and Larinia 5.26% are the rarest genera represent single-single specie both. Statistical analysis show that specie richness (D) = 5.77, Simpson index (1-D) = 0.87, Shannon index (H) = 2.33. Diversity of spiders was evenly distributed and calculated Evenness value was H/InS = 0.5408. There is also few atypical species and Fisher alpha estimate high value (Fisher α) = 4.42. Chao-1 estimated we have reported 22 species.

A presente pesquisa foi realizada para explorar a fauna de aranhas do vale Buner, em um estudo taxonômico realizado de fevereiro de 2018 a janeiro de 2019. Para esse fim, foram coletadas amostras, quatro vezes por mês, a partir de 4 subdistritos: Daggar, Gagra, Mandan e Totalai. Foram utilizados dois métodos, coleta manual e rede de varredura, para a obtenção das amostras. Durante o dia e a noite, foram pesquisados três habitats: área árida, área agrícola e área de construção. Foram coletadas 534 amostras de aranha em quatro locais de amostragem, sendo que 379 pertenciam à família Araneidae. Após a confirmação, as espécies identificadas pertenciam a 8 gêneros (Neoscona, Argiope, Cyclosa, Araneus, Cyrtophora, Larinia, Erivoxia e Poltys) e a 19 espécies (18 delas foram identificados em seu nível de espécie, enquanto uma única foi identificada em seu nível genérico). O gênero Neoscona foi dominante (26,31%), com 5 espécies, seguido pelos gêneros Argiope (21,05%), com 4 espécies, Cyclosa (15,78%), com 3 espécies, e Cyrtophora e Araneus (10,52%), com 2 espécies. Poltys e Larinia (5,26%) são os gêneros mais raros, representando a mesma espécie. A análise estatística mostrou que a riqueza de espécies (D) foi de 5,77, o índice de Simpson (1-D) foi de 0,87 e o índice de Shannon (H) foi de 2,33. A diversidade de aranhas foi distribuída uniformemente, e o valor calculado da uniformidade foi H / InS = 0,5408. Também existem poucas espécies atípicas, e o alfa de Fisher (Fisher α) estimou o valor de 4,42. Já Chao-1 estimou 22 espécies.

Family-specific chemical profiles provide potential kin recognition cues in the sexually cannibalistic spider Argiope bruennichi.

Kin recognition, the ability to detect relatives, is important for cooperation, altruism and also inbreeding avoidance. A large body of research on kin recognition mechanisms exists for vertebrates and insects, while little is known for other arthropod taxa. In spiders, nepotism has been reported in social and solitary species. However, there are very few examples of kin discrimination in a mating context, one coming from the orb-weaver Argiope bruennichi. Owing to effective mating plugs and high rates of sexual cannibalism, both sexes of A. bruennichi are limited to a maximum of two copulations. Males surviving their first copulation can either re-mate with the current female (monopolizing paternity) or leave and search for another. Mating experiments have shown that males readily mate with sisters but are more likely to leave after one short copulation as compared with unrelated females, allowing them to search for another mate. Here, we ask whether the observed behaviour is based on chemical cues. We detected family-specific cuticular profiles that qualify as kin recognition cues. Moreover, correlations in the relative amounts of some of the detected substances between sexes within families indicate that kin recognition is likely based on subsets of cuticular substances, rather than entire profiles.

First Report on Mermithid Parasitism (Enoplea: Mermithidae) in a Southeast Asian Spider (Araneae: Araneidae).

Details about the record of ajuvenile mermithid roundworm parasitizing the bark spiderCaerostris sumatrana Strand,1915 from Thailand are presented.The morphology and ecology of both organisms is discussed. Morphological features suggest this juvenile nematode belongs to the genus cf.- Aranimermis. Due to the sub adult stage of parasite, identification to species-level was not possible. This first report of a nematode infection in C. sumatrana with several recent findings from other studies significantly adds to the current inventory of mermithids parasitizng spiders. Moreover, our finding is among the first record of this host-parasite interaction from Southeast Asia.

Artificial light at night alters life history in a nocturnal orb-web spider.

The prevalence of artificial light at night (ALAN) is increasing rapidly around the world. The potential physiological costs of this night lighting are often evident in life history shifts. We investigated the effects of chronic night-time exposure to ecologically relevant levels of LED lighting on the life history traits of the nocturnal Australian garden orb-web spider (Eriophora biapicata). We reared spiders under a 12-h day and either a 12-h natural darkness (∼0 lux) or a 12-h dim light (∼20 lux) night and assessed juvenile development, growth and mortality, and adult reproductive success and survival. We found that exposure to ALAN accelerated juvenile development, resulting in spiders progressing through fewer moults, and maturing earlier and at a smaller size. There was a significant increase in daily juvenile mortality for spiders reared under 20 lux, but the earlier maturation resulted in a comparable number of 0 lux and 20 lux spiders reaching maturity. Exposure to ALAN also considerably reduced the number of eggs produced by females, and this was largely associated with ALAN-induced reductions in body size. Despite previous observations of increased fitness for some orb-web spiders in urban areas and near night lighting, it appears that exposure to artificial night lighting may lead to considerable developmental costs. Future research will need to consider the detrimental effects of ALAN combined with foraging benefits when studying nocturnal insectivores that forage around artificial lights.

Influence of aging on brain and web characteristics of an orb web spider.

In animals, it is known that age affects the abilities of the brain. In spiders, we showed that aging affects web characteristics due to behavioral alterations during web building. In this study, we investigated the effects of age on the associations between morphological changes to the spider brain and changes in web characteristics. The orb web spider Zygiella x-notata (Araneae, Araneidae) was used to test these relationships. Experiments were conducted on young (19 ± 2 days after adult molt, N = 13) and old (146 ± 32 days, N = 20) virgin females. The brain volume decreased with age (by 10%). Age also had an impact on the number of anomalies in the capture area generated during web building. The statistical relationships between the volume of the brain and web characteristics showed that there was an effect of age on both. Our results showed that in spiders, aging affects the brain volume and correlates with characteristics (anomalies) of the web. As web building is the result of complex behavioral processes, we suggest that aging affects spider behavior by causing some brain alterations.