Behavioral ecology of wasp-spider interactions: The role of webs, chemicals, and deception

Predator-prey interactions are integral to the maintenance of community structure and function. Predators and prey use multiple cues to detect and assess each other, and identification of these cues is necessary to understand how selection operates to shape predator-prey interactions. Mud-dauber wasps (Sphecidae), one of the main predators of spiders, prefer araneids (two-dimensional web-building spiders) over derived araneoids, (three-dimensional web-building spiders). Predation pressure by spider-hunting wasps is considered a key factor in the evolution of 3D web-building spiders. However, the proximate basis of such preference was not known.;By conducting behavioral and chemical assays I have determined that Sceliphron caementarium wasps recognize araneids as potential prey due to the presence of chemicals present on their silk and cuticle. By analyzing cuticular extracts of spiders in several families, I have shown that all spiders that are taken by wasps have similar cuticular chemistry; however, all spiders that have that similar chemistry are not taken by wasps. Indeed, spiders' antipredator behavior, morphology and web architecture are important factors that influence prey capture by wasps.;Though not captured by S. caementarium, derived araneoids are readily captured by another sphecid, Chalybion californicum. Examinations of the hunting behavior of C. californicum towards Achaearanea tepidariorum (cobweb spider, Theridiidae, derived araneoid) reveals that the antipredator behavior of the cobweb spider changes over its ontogeny. Whereas small-sized spiders drop off their webs (i.e., seem to treat wasp as predators), medium and large-sized spiders attempt to warap wasps in silk (i.e., seem to treat wasps as prey).;Besides araneids, Sceliphron also capture jumping spiders: however, they do not capture Peckhamia picata, a jumping spider that mimics ants. Chemical analyses demonstrate that ant mimics lack the chemical signature of a typical jumping spider but they chemically resemble their model ant, Camponotus sp. My results suggest that P. picata uses visual mimicry to avoid predatory jumping spiders, and employs chemical information to elude wasps and perhaps ants. Thus P. picata uses different sensory modalities to deceive multiple audiences.;My study highlights the importance of spider webs, chemistry and behavior in shaping interactions between wasps and spiders, and contributes to our understanding of the use of multimodal cues in predator-prey interactions.