Eliminating host-mediated effects demonstrates that Bt corn expressing Cry1F has no adverse effects on Cotesia marginiventris

Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) is a solitary, larval endoparasitoid, and important natural enemy of noctuid moths. C. marginiventris attacks 1^st and 2^nd instars and its larvae feed on host hemolymph and tissue and emerge from the host to pupate. Thus, C. marginiventris may be exposed to Bt proteins when their host larvae feed on Bt crops. To eliminate host quality mediated-effects that occur when susceptible hosts fed Bt crops become sub-optimal, we used Bt-resistant fall armyworm, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) larvae as hosts and evaluated the potential impact of Cry1F expressing corn (Mycogen 2A517) on several fitness parameters of C. marginiventris over three generations. Survival, parasitism, development time of larval and pupal stages, adult longevity and offspring sex ratio of C. marginiventris were observed. Our results demonstrated there were no differences when resistant S. frugiperda larvae reared on either Bt or control corn leaves were used as the host. This indicates that this parasitoid species is not affected by Cry1F.