Fitness, acceptance and olfactory responses of Trichogramma pretiosum on eggs of Spodoptera frugiperda fed with Cry1Ac soybean Natália ALV

Abstract

Spodoptera frugiperda (Smith) (Lepidoptera Noctuidae) is naturally tolerant to MON 87701 × MON 89788 soybean that expresses the Cry1Ac protein from Bacillus thuringiensis (Bt). Therefore, there are reports of outbreaks of this pest in fields where this technology has been cultivated. To support an environmental risk assessment, it is important to investigate the impacts of this technology on non-target organisms like the parasitoids of the genus Trichogramma, which can be used to manage this pest. In this study, we accessed: (i) the biology of a field population of S. frugiperda on MON 87701 × MON 89788 soybean; (ii) the impacts of the eggs produced by S. frugiperda fed with this soybean on the fitness and acceptance of the egg parasitoid Trichogramma pretiosum Riley (Hymenoptera Trichogrammatidae); and, (iii) the olfactory responses of this parasitoid to the volatiles of Bt and non-Bt soybean plants oviposited by S. frugiperda. The results of the biology of a field population of S. frugiperda when fed with Bt and non-Bt soybeans showed a similar total survival and cycle duration. No significant effects of the Bt soybean plants were observed in the life table parameters of S. frugiperda. Fitness and oviposition preference of T. pretiosum on eggs of S. frugiperda that fed with Bt and non-Bt soybeans were not different. Furthermore, the olfactory responses of this parasitoid to volatiles emitted by oviposited Bt and non-Bt soybeans were similar. These results suggest that there are no direct and indirect effects of S. frugiperda eggs fed with Bt soybean on the parasitoid fitness and acceptance, and also that T. pretiosum do not distinguish between Bt and non-Bt soybean plants oviposited by this pest. Therefore, this technology showed no adverse effects on T. pretiosum, which can help mitigate S. frugiperda outbreaks within an integrated pest management context.