Chemical Cues from an Introduced Predator (Mantodea, Mantidae) Reduce the Movement and Foraging of a Native Wolf Spider (Araneae, Lycosidae) in the Laboratory

Abstract

Exotic predators are sometimes introduced into agricultural ecosystems to aid in biological control of crop pests. Besides direct effects, such as consumption, introduced predators can have indirect effects on smaller predators and herbivores through chemically mediated shifts in behavior. We tested whether the chemical cues of Tenodera aridifolia sinensis (the Chinese praying mantis) affected the movement and foraging of the native wolf spider Pardosa milvina. Comparisons of behavior in paired-treatment arenas revealed that P. milvina spent a greater amount of time immobile, had a greater residence time, and moved at a significantly slower speed on T. a. sinensis cues relative to a blank control. While this reduced movement may reduce the probability of predation, it has a cost in terms of foraging. P. milvina gained less mass and had a smaller increase in abdomen width after foraging in microcosms containing T. sinensis cues relative to blank controls. The response of P. milvina to chemical cues of mantids is similar to the response of this small wolf spider to chemical cues from a larger, coexisting wolf spider predator. While these effects appear important in the lab, further studies are needed to evaluate the impact of cues on populations of P. milvina in the field.