Meeting Abstract
Among the parasites of insects, endoparasitoids impose a unique challenge to host defenses because they use the body of another insect for the development and maturation of their eggs and/or larvae. Tachinid flies are highly specialized acoustically-orienting parasitoids that release mobile larvae, which burrow into the host’s body to feed. Larval feeding typically leads to host death. We investigated the possibility that coevolving Teleogryllus oceanicus field crickets employ post-infestation strategies to maximize survival when infested with the larvae of the parasitoid fly Ormia ochracea. Using crickets from the Hawaiian island of Kauai, where the parasitoid co-occurs, and crickets from the Cook Islands (Mangaia), where the parasitoid is absent, we evaluated fitness consequences of infestation by comparing feeding behavior, reproductive capacity, and survival of males experimentally infested with O. ochracea larvae. We also evaluated genetic mechanisms underlying host responses by comparing gene expression in crickets infested with fly larvae for different lengths of time against that of uninfested control crickets. We did find some evidence for population differences in fitness (spermatophore production) and survival (total survival time post-infestation), although in both cases significant population effects 1) were not associated with the slope of the response to different numbers of larvae and 2) only emerged from models containing body condition at one but not both time points evaluated. Patterns of gene expression similarly show some evidence of population differences in response to infestation, but we did not find evidence for consistent differences in genes associated with immunity or the stress response.
