Development of Helicoverpa spp. in Bt maize expressing different proteins

Abstract

The objective of this work was to evaluate the biological responses of Helicoverpa zea and Helicoverpa armigera (Lepidoptera: Noctuidae) in maize hybrids expressing different proteins. The Cry1F, Cry1A(b), Cry1A.105 + Cry2Ab2, and Vip3A proteins and their isogenic conventional counterparts were evaluated. Larvae were fed on spikelets of Bt and conventional maize, which were changed every two days. The variables evaluated were: survival 48 hours after hatching, larval survival, larval and pupal weight, larval development period, and pre‑imaginal period. There was a significant interaction between Bt maize event and Helicoverpa species for all evaluated biological variables. Helicoverpa armigera larvae showed higher survival 48 hours after hatching on maize expressing the Cry1F and Vip3 proteins when compared to H. zea. Lethal period was greater for H. armigera than for H. zea, but, in maize expressing Cry1A(b) protein, it was four times lower. There were no survivals for both Helicoverpa species in the evaluated Bt hybrids. In isogenic conventional counterparts, the adaptation index of H. armigera was higher than that of H. zea, which indicates greater ease of adaptation to the environment of that species.