Meeting Abstract
Repeated exposure to high daily temperatures can have large impacts on ectothermic organisms, especially if those temperatures approach the upper thermal limits. The effects of fluctuating, sublethal temperatures have been explored for single organisms, but little is known with regards to multi-species systems. Cotesia congregata is a hymenopteran parasitoid that uses the larval stage of the sphinx moth Manduca sexta as a host for larval development. Host manipulation early in parasitization is crucial for successful wasp development. Exposure to stressful conditions soon after oviposition holds the potential to disrupt physiological processes vital to C. congregata survival. Previous work in this system has shown that parasitized M. sexta caterpillars reared continually at 30°C±10°C have no parasitoid emergence, and exhibit abnormal developmental traits. To explore the effects of temperature and repeated heat stress on early parasitoid development, we subjected 3rd instar M. sexta parasitized with C. congregata to one of two diurnally fluctuating “heat shock” treatments (daily maximum of 40°C or 42°C) for 1-4 days. Under control conditions, wasp emergence occurred in all parasitized M. sexta caterpillars. Our results from the “heat shock” treatments show that both maximum temperature and the number of exposures decrease the proportion of hosts with parasitoid emergence. Hosts without wasp emergence displayed abnormal physiology and development, and inevitably perished as larvae. Our results indicate that both the temperature and repetition of heat stress have important consequences for host-parasitoid interactions.
