There were no significant differences in the population densities of A. lucorum
found in Bt cotton and non-Bt cotton plots, whether one compared those that had received insecticide
treatments or those that had not. However, population densities of A. lucorum were significantly lower in
pesticide treated plots than in controls. Furthermore, there were no significant differences in the net
reproductive rates, generation times or intrinsic rates of increase of A. lucorum when reared on either Bt
or non-Bt cotton cultivars. These results suggest that Bt cotton has no direct positive or negative effects
on the biology of A. lucorum, so the most logical explanation for the observed outbreaks is the decrease in
pesticide applications following the commercial release of Bt cotton.