Context-dependent fitness effects of behavioral manipulation by a parasitoid

Many true parasites and parasitoids modify the behavior of their host, and most of these changes are thought to benefit the parasites. However, field tests of this hypothesis are scarce. We previously showed that braconid parasitoids (Glyptapanteles sp.) induce their caterpillar host (Thyrinteina leucocerae) to behave as a bodyguard of the parasitoid's pupae; they stand bent over the pupae and violently lash out at predators approaching them, resulting in reduced predation of parasitoid pupae on guava trees in the field. In contrast, we show here that this behavioral manipulation does not result in increased parasitoid survival on eucalyptus trees, an introduced host plant species. Hence, the effects of behavioral manipulation of the host depend on the ecological context. We hypothesize that this is due to a different species composition of the community of predators and hyperparasitoids on the 2 host plant species. Our results show that fitness effects of behavioral manipulation should be evaluated in a setting that includes all relevant components of the natural food web. Copyright 2009, Oxford University Press.