Evaluation of transgenic tobacco expressing two insecticidal genes to delay resistance development of Helicoverpa armigera

The resistance ratio of Helicoverpa armigera to Cry1Ac insecticidal protein from Bacillus thuringiensis (Bt) is 13.1- and 3.02-fold after 18 generatio ns of selection by transgenic tobacco expressing Bt or two (Bt and CpTI) in secticidal protein genes, in which the average corrected mortality for each selection treatments is about 60%. The mortality of selected population by transgenic Bt gene tobacco is significantly lower than the control strain when fed on transgenic tobacco plants. The mortality of the selected popula tion by transgenic two genes tobacco was not significantly different from t he control strain. This is the first experiment under laboratory condition which has proved that transgenic two genes tobacco could significantly dela y resistance development of H. armigera compared with one gene.