Key factors in managing transgenic Bt cottons for the future are to have an effective resistance management strategy. An essential component of any such strategy is to establish a resistance monitoring program. The core components of this project address resistance monitoring as well as examine the performance of transgenic cotton (two genes) in relation to resistance management. To develop an effective resistance management strategy it is important to understand the mechanisms of resistance as well as the possible behaviour changes that may occur within a resistant population as compared to a susceptible one. If the industry is to continue to use Dipel® and other foliar Bts, then the question of cross resistance between Bt proteins also needs to be evaluated.

To undertake this type of research it is important to develop colonies resistant to both Bt proteins used in transgenic cotton (i.e. Cry 1Ac and Cry 2Ab) and foliar Bts (Dipel®). To establish resistant colonies, surviving larvae have been reared in the laboratory. A colony with low to moderate resistance to MVP® (Cry 1 Ac), and lower order cross-resistance to fully expressing Bt transgenic cotton plants has been established. Further selection of the strain with MVP® and Ingard® plants should result in fully resistant colonies.