Everyone's a loser: late instar parasitism of whitefly hosts by Encarsia inaron has negative consequences for both parasitoid and host

 

Despite strong evolutionary pressure for an ovipositing parasitoid to use only hosts with high suitability, there are examples of parasitoid attacks that fail. Here we document one such instance, when a parasitoid fails to discriminate against an inappropriate host life stage, resulting in negative consequences for both the parasitoid and host.  Encarsia inaron was originally imported to control Siphoninus phillyreae, but readily parasitizes and completes development in both Bemisia tabaci and Trialeurodes abutiloneus. When younger instars of both B. tabaci and T. abutiloneus were parasitized, adult wasps emerged. In older instars, however, adult parasitoids rarely emerged; rather, adult whiteflies were produced. Dissections over time showed that the wasp larvae continued to develop within these whiteflies. These adult whiteflies suffered approximately 60% reduced fecundity compared to non-parasitized adults and ultimately died as a result of parasitism. Parasitoid larvae attempted to complete development within the host abdomen, but were not successful. We speculate that both the host arrestment strategy of the parasitoid and defensive strategies of the host are mismatched in this system. Such systems represent an evolutionary opportunity for life history transitions and deserve further study.