FIELD AND LABORATORY EVALUATIONS OF TRANSGENIC BACILLUS-THURINGIENSISCORN ON SECONDARY LEPIDOPTERAN PESTS (LEPIDOPTERA, NOCTUIDAE)

Field corn, genetically engineered to produce a protein derived from B acillus thuringiensis kurstaki strain HD-1, was evaluated for its effe cts on larvae of the noctuid species Agrotis ipsilon (Hufnagel), Papai pema nebris (Geunee), Pseudaletia unipuncta (Haworth), and Helicoverpa zea (Boddie). No B. thuringiensis corn effects were observed on larva l survival, pupal weight, or days to adult emergence for A. ipsilon or P. nebris; however, P. unipuncta reared on B. thuringiensis leaf extr act were 0.068 g lighter in pupal weights, delayed for 8 d in preimagi nal development (from 33 to 41 d), and showed trends for 11-25% lower survival. Reduced survival and a 4-d delay in preimaginal development also was observed for H. zea reared on B. thuringiensis-treated meridi c diet. In 1994 and 1995, transgenic B. thuringiensis corn and non-B. thuringiensis corn seed was planted under field conditions. Eighty B. thuringiensis and non-B. thuringiensis plants were artificially infest ed with early instars of the 4 noctuid species, then evaluated for dam age (leaf feeding, stalk cutting, ear-tip feeding). There were no diff erences between B. thuringiensis and non-B. thuringiensis corn damage caused by A. ipsilon. In 1994, P. nebris caused significantly less lea f-feeding damage to B. thuringiensis corn than non-B. thuringiensis co rn. In addition, P. unipuncta and H. zea caused significantly less dam age to B. thuringiensis corn leaves. H. zea survived on and caused dam age to B. thuringiensis corn ears, and even though there were fewer ea rs damaged, there was no difference in the number of live larvae per p lant on B. thuringiensis corn than on non-B. thuringiensis corn.