Tuesday, August 3, 2010 - 2:30 PM

COS 42-4: Double deception: ant-mimicking spiders fool both visually and chemically-oriented predators

Divya Uma and Martha Weiss. Georgetown University

Background/Question/Methods

Mimicry systems provide some of the most striking examples of adaptation in the natural world.  Mimics can resemble models in a range of sensory modalities (e.g., visual, chemical, acoustic, textural, and behavioral) and often employ multimodal signals to gain protection from predators, or secure access to prey, hosts or mates. However, mimicry involving both visual and chemical modalities in a single organism, in which the different sensory modalities are directed at different audiences, has not been previously described. Here we report an ant-mimicking jumping spider, Peckhamia picata, that employs different sensory modalities to deceive different arthropod predators. Using both behavioral and chemical assays, we tested the hypotheses that the ant-mimicking spider a) deceives visually-oriented jumping spiders, b) deceives chemically-oriented mud-dauber wasps, and c) chemically resembles its model ants.

Results/Conclusions Our behavioral results reveal that whereas visually-oriented predatory jumping spiders attack non-mimetic spiders, they avoid ant-mimicking spiders as well as model ants. Additionally, while chemically-oriented mud-dauber wasps readily capture non-mimetic spiders, they do not take ant-mimicking spiders.  Gas chromatography/ mass spectrometric analyses reveal that P. picata lack the cuticular chemical compounds found on non-mimic jumping spider that are taken by wasps, and that they chemically resemble their model ants. Thus, it seems that Peckhamia uses visual mimicry to avoid predation by jumping spiders and employs chemical information to elude wasps and perhaps ants. To our knowledge, use of two modalities, each used to fool a different audience, has not been previously reported. We believe that the utilization of multimodal cues to deceive multiple audiences is likely to be common in mimicry systems.