Phenotype Matching and Trophic Complexity in the wild Parsnip-parsnip Webworm Interaction

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

Coevolution is the process by which interacting organisms act reciprocally as selective agents on one another. Coevolutionary responses between the parsnip webworm and its wild parsnip hostplant are dramatically manifested in the chemistry of the two species. Parsnips defend themselves by producing an array of toxins called furanocoumarins; webworms disarm these toxins with detoxification enzymes called cytochrome P450s. Webworms and parsnips were, like many other invasive weeds and insect pests, introduced from Europe; throughout their range in the midwestern U.S., the defense profile of the plants matches the detoxification profile of the insect, suggesting intense reciprocal responses. This chemical matching may be an artifact of introduction; in Europe, this two-species interaction is embedded in a more complex community, with predators, parasites, and alternate hostplants that could reduce the intensity of the interaction. This project is aimed at comparing the dynamics of coevolutionary responses in these two introduced species, both in Europe, where the interaction originally evolved, and in the U.S., where these species have been interacting in a novel environment. The effects of increasing community complexity and length of association on the frequency of chemical matching will be determined, as will the consequences of mismatching for both the herbivore and the hostplant.