RELEVANCE OF HELICOVERPA EMERGING FROM BT CROPS
A major threat to the longevity of Bt cotton is Helicoverpa's ability to develop genetic resistance to high doses of Bt toxins. To counter this threat, refuges are planted to produce large numbers of moths to dilute any moths emerging from Bt crops which could be carrying Bt resistant genes. Using cages (Fig. 1), we compared the number of moths emerging from Bt cotton and productive refuges and their levels of resistance.