Abstract:
The introduction of transgenic cotton expressing the CrylAc insecticidal crystal protein from Bacillus thuringiensis (Bt) is expected to provide the basis for pest management in cotton in the near future and to reduce the usage of pesticides in the industry. However the potential for over-reliance on Bt-cotton to result in the development of resistance to Bt by Helicoverpa armigera has been identified (Edge, 1994). Recognising that his resistance would undermine the basis for pest management the cotton industry has devoted resources to addressing the problem. Experience with resistance to synthetic chemical insecticides has shown that there are options for managing resistance. One of the major options being examined is the provision of alternative means of control that will complement the Bt cotton. Among these alternatives is the identification of new insecticidal crystal proteins from Bt. Over the past four years an additional 35 Bt insecticidal crystal proteins have been recorded, demonstrating that the diversity of these insecticidal toxins is much greater than previously recognised. We have taken advantage of new molecular technologies to search for new insecticidal crystal proteins that can be used to complement CrylAc in a resistance management program.
