Superparasitism Increases Parasitoid Production and High Fitness Costs are Associated with Resistance of Diatraea saccharalis to the Parasitism of Cotesia flavipes

The koinobiont endoparasitoid Cotesia flavipes Cameron, 1891 (Hymenoptera: Braconidae) is mass reared in biofactories for subsequent release in sugarcane fields for the management of the sugarcane borer Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae) in Brazil. Knowledge about parasitism is elementary for improvements in parasitoid mass rearing. For the present work, C. flavipes offspring production was measured by evaluating (1) the position of the parasitoid sting in the host body (anterior or posterior), (2) superparasitism (stings from two different parasitoids in the same host), or (3) sequential stings from the same parasitoid in different hosts with immediate stings or with 24 h intervals between stings. Moreover, the evolution of host resistance to parasitism in larvae that avoided parasitism was investigated. Parasitism in different host body positions did not influence parasitoid offspring production, but superparasitism using two different C. flavipes wasps in the same host resulted in increased production of parasitoid offspring per host. In the experiments of immediate sequential stings, only the first parasitoid sting resulted in the production of parasitoid offspring, but host development was impaired up until the 10th sequential sting from the same parasitoid. When 24 h intervals were taken between stings, parasitoids were able to produce offspring up to the 2nd sting. Host resistance to parasitism was not linked to changes in the measured host immunological features but host resistant population presented reduction in reproduction capacity and very high fitness costs avoided the establishment of a resistant population in the long term. The results obtained in the present investigation are useful for improvements in the rearing process of C. flavipes in biofactories.