Effect of Bt Soybean on Larvae of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Abstract

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) causes economically significant damage to soybeans Glycine max (L.) Merrill (Fabaceae: Phaseoleae). The genetically modified soybean expressing the Cry1Ac protein of Bacillus thuringiensis Berliner, which is toxic to lepidopterans, is a potential alternative tool to manage this pest. Bioassays with H. armigera larval instars were conducted with Bt (Cry1Ac) and nonBt soybean plants in order to evaluate the efficacy of control with the modified cultivar. Bt soybean affected the mean time of mortality in each larval instar, but its efficacy was not affected by the larval stage. Mortality was 100% in all six instars, indicating that the Bt soybean expressing the Cry 1Ac protein is an efficient control tactic for this pest.