The evolutionary processes that shape host-parasitoid coexistence in a changing environment are poorly understood. We examined the large-scale distribution of highly specialised polysphinctine Darwin wasps associated with spiders along an elevational gradient and tested the hypothesis that distribution and parasitism rates depend on elevation, habitat type and the species and age composition of the host community. Further, on the basis of a large-scale dataset, we examined the hypothesis that three-dimensional webs in spiders may be an evolutionary adaptation against polysphinctine parasitoids. We found significant variation in parasitoid distribution and parasitism rates along a 1500 m elevational gradient in central Europe. The optimal model showed a humped shape for the parasitism rate on an elevational gradient. Overall, we found relatively low parasitism rates (4%) on spiders, with the highest parasitism rates in non-forested riparian vegetation and the lowest in agroecosystems. Rates of parasitism varied significantly among spiders forming different types of webs (foraging guilds). Spiders spinning 3D webs were dominant in the spider community, but parasitism on them was lower compared to spiders spinning 2D webs, probably because of the defensive function of the 3D web architecture. The bottom-up approach, in which the entire spider host community is analysed for parasitism rate, supports the hypothesis that 3D webs are evolutionarily novel and could have arisen as a result of the need for defence against enemies such as parasitoids.

• Klíčová slova
• elevation, host range, mid‐domain effect, parasitism rate, parasitoid distribution, parasitoid–host interaction,
• Publikační typ
• časopisecké články MeSH

Neonicotinoids are thought to have negligible repellent or anti-feeding effects. Based on our preliminary observations, we hypothesized that the contamination of spider prey with commonly used neonicotinoids has repellent or feeding deterrent effects on spiders. We tested this hypothesis by providing prey treated or not with field-realistic concentrations of neonicotinoids to the spiders and determining the number of (a) killed only and (b) killed and eaten prey. We exposed adult freshly molted and starved Pardosa agrestis, a common agrobiont lycosid species, to flies treated with neonicotinoids (acetamiprid, imidacloprid, thiacloprid and thiamethoxam) at field-realistic concentrations or with distilled water as a control. There were no effects of the exposure of the prey to neonicotinoids on the number of flies captured. However, the spiders consumed less of the prey treated with neonicotinoids compared to the ratio of control prey consumed, which resulted in increased overkilling (i.e., killing without feeding). In female P. agrestis, the overkilling increased from only 2.6% of control flies to 25-45% of neonicotinoid-treated flies. As the spiders avoided consuming the already captured neonicotinoid-treated prey, the sublethal effects of neonicotinoids extend beyond the simple attractivity/deterrence of the prey itself. The present study demonstrated that prey overkilling serves as a physiological response of spiders to the contact with the prey contaminated with agrochemicals. We speculate that primary contact with neonicotinoids during prey capture may play a role in this unexpected behavior.

• MeSH
• dusíkaté sloučeniny toxicita   MeSH
• farmy MeSH
• insekticidy toxicita   MeSH
• neonikotinoidy toxicita   MeSH
• pavouci fyziologie   MeSH
• stravovací zvyklosti účinky léků   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acetamiprid MeSH Prohlížeč
• dusíkaté sloučeniny MeSH
• imidacloprid MeSH Prohlížeč
• insekticidy MeSH
• neonikotinoidy MeSH

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.

• Klíčová slova
• Agamomermis, Aranimermis, Caerostris sumatrana, Thailand, orb-web spider, parasitoid,
• Publikační typ
• časopisecké články MeSH