Print PageSlug caterpillars (Limacodidae) are known for their unusual morphologies; some species are colorful and possess stinging spines while others are cryptic in their coloration. Previously, we have demonstrated that caterpillar species with stinging spines are protected from predation, but these same well-defended caterpillars appear to be more susceptible to parasitism by parasitoid flies (Diptera) and wasps (Hymenoptera). Parasitoid species, in turn, appear to partition caterpillar hosts by size. In a previous observational study, we found that parasitoid wasps appear to preferentially attack small, early-instar limacodid hosts while parasitoid flies attack larger, late-instar limacodid hosts. In that study, host size was confounded with time because parasitoid wasps are abundant early in the season, when limacodid hosts are small, while parasitoid flies are more common later in the season, when limacodid hosts are large. To test whether parasitoids partition limacodid hosts based on caterpillar size and do not simply attack the most abundant size class found during their flight season, we conducted a manipulative experiment in which we paired small and large limacodids in the field and recorded which size classes were preferentially attacked by a variety of parasitoid species at different times during the field season.
Results/Conclusions
We found that initial length of the limacodid caterpillar was not a significant predictor of whether they were likely to be parasitized. In other words, small and big caterpillars were equally likely to be parasitized. However, we found that small caterpillars were more likely to be parasitized by wasp parasitoids than were big caterpillars. Furthermore, big caterpillars were more likely to be parasitized by fly parasitoids than were small caterpillars. The results from our manipulative experiment support our earlier findings from our observational study that fly and wasp parasitoids partition the community limacodid caterpillar hosts by size.
phone 202-833-8773