| Field populations of Helicoverpa zea (Boddie) larvae were not significantly lower on transgenic corn expressing the Cry1Ab endotoxin of Bacillus thuringiensis (Berliner) (Bt) compared with their near-isogenic parent lines, however total numbers of large larvae were lower on the transgenic varieties. Diatraea grandiosella (Dyar) caused limited damage to the transgenic corn, but the Bt varieties did not yield significantly better than their near-isogenic, non-Bt parents.; Laboratory studies were conducted to determine the response of D. grandiosella to lyophilized whorl, stalk, shank, husk, silk, or kernel transgenic corn tissues expressing Bt toxin. Larvae fed diet containing conventional corn weighed more and had greater body length than larvae fed diet containing the Bt corn tissue. Larvae fed diet with kernel tissue expressing Bt toxin had greater weight and body length than larvae fed diet with the other Bt corn tissues. |
