Adaptive Reproductive Strategies of an Ectoparasitoid under the Stress of Its Entomopathogenic Fungus .

Complex interspecific relationships between parasites and their insect hosts involve multiple factors and are affected by their ecological and evolutionary context. A parasitoid (Hymenoptera: Bethylidae) and an entomopathogenic fungus (Hypocreales: Cordycipitaceae) shared the same host in nature, (Coleoptera: Cerambycidae). They often encountered the semi-enclosed microhabitat of the host larvae or pupae. We tested the survival and reproduction of the parasitoid's parent and its offspring fitness under different concentrations of suspension. The results show that parent females carrying higher concentrations of the pathogen shorten the pre-reproductive time and regulate their own fertility and their offspring's survival and development. This minimal model of the interspecific interactions contains three dimensionless parameters, vulnerability (), dilution ratio (), and , which were used to evaluate the mortality effect of the parasitoid on its host under the stress of the entomopathogenic fungus . We compared the infection and lethal effect of the fungus with different concentrations to the parasitoid and the host larvae . At higher concentrations of the pathogen, the parasitoid parent females shorten the pre-reproductive time and regulate their own fertility and their offspring's survival and development. At moderate concentrations of the pathogen, however, the ability of the parasitoid to exploit the host is more flexible and efficient, possibly reflecting the potential interspecific interactions between the two parasites which were able to coexist and communicate with their hosts in ecological contexts (with a high overlap in time and space) and cause interspecific competition and intraguild predation.