FIELD-EVALUATION OF TRANSGENIC TOBACCO CONTAINING GENES ENCODING BACILLUS-THURINGIENSIS DELTA-ENDOTOXIN OR COWPEA TRYPSIN-INHIBITOR - EFFICACY AGAINST HELICOVERPA-ZEA (LEPIDOPTERA, NOCTUIDAE)

Transgenic tobacco plants expressing Bacillus thuringiensis var. kurstaki HD-73 delta-endotoxin or cowpea, Vigna unguiculata, trypsin inhibitor (CpTI) were evaluated for efficacy against artificial infestations of Helicoverpa zea (Boddie) under field conditions. Mortality of H. zea larvae was significantly higher and leaf damage significantly lower for the genotype containing Bacillus thuringiensis gene compared with nontransgenic control. Few H. zea larvae survived beyond first instar on the Bacillus thuringiensis genotype. Larval mortality was also higher and leaf damage lower on the CpTI genotype than its corresponding control, but the effect was less consistent and less pronounced than that produced by the Bacillus thuringiensis genotype. Neither transgenic genotype had a significant effect on natural infestations of the other phytophagous or predacious insects that were monitored.