Corn earworm, Helicoverpa zea Boddie, cause ear damage and yield loss every year in the USA. Transgenic hybrids have been developed to express a insecticidal endotoxin from Bacillus thuringiensis (Bt) to control these pest once they begin to feed on the host plant.

     The objective of this experiment was to compare grain yield of a commercial hybrid with differing numbers of kernels lost due to simulated CEW feeding.  This experiment was random and replicated four times.  Treatments consisted of removal of 0, 10, 25, 50, and 100 kernels from ear at R5.  This hybrid was planted early and traited to be assured there would be no actual CEW damage. Plots were harvested at 15.5% moisture and yeild data was subjected to analysis of variance at the 0.05 level of significance. Results will be presented.