Efficacy of Insect-Protected Maize (Bt-11) Against Asiatic Corn Borer (Ostrinia furnacalis Guenee)

Three experimental hybrid versions of NK5445 Bt, a hybrid maize developed by Syngenta Seed Company, along with three checks were subjected to repeated artificial infestation with Asiatic corn borer (ACB) egg masses and neonate larvae in a screenhouse study to test the efficacy of Bt-11 containing the truncated gene cry1Ab. Results show that all the three experimental hybrids were consistently highly resistant to ACB across three assessment periods during the vegetative stage. In contrast, the three check entries (non-Bt isogenic hybrid of NK5445, sweet corn hybrid Sugar 73, and NK5468, a commercial non-Bt hybrid), showed s everal elongated feeding holes on as much as two-thirds of the leaves. At harvest, the checks showed severe damage to the stalks, ears, ear shanks and tassels, and relatively minor damage to the kernel. Pupae of A CB were observed inside the stalks. The NK5445 Bt entries showed little or no damage to the stalk, ear shanks, ears, tassels, and kernels. The data clearly demonstrated the efficacy of Bt-11 in controlling the A CB under screenhouse conditions. The presence of four other insect species in both checks and NK5445 Bt plants, possibly introduced through the field-collected egg masses used for infestation, is an indication of the safety of the use of Bt-11 concerning non-target insects.