IN VITRO CROSS RESISTANCE STUDIES WITH THE VEGETATIVE INSECTICIDAL PROTEIN VIP3A SUPPORT THE INSECT RESISTANCE MANAGEMENT STRATEGY FOR VIPCOTTM

摘要

The introduction into the US of cotton varieties expressing Vip3A will bring a novel toxin into a landscape that is dominated by Bollgard varieties expressing Cry1Ac. The recent introduction of Bollgard II has added Cry2Ab to this landscape. As part of the development of a resistance management strategy for Vip3A, we have undertaken a series of in vitro binding studies using brush border membrane vesicles prepared from the major cotton pests, Heliothis virescens and Helicoverpa zea. Competition binding studies and ligand blotting assays using biotinylated Vip3A, Cry1Ac, and Cry2Ab2 have demonstrated that these toxins have distinct binding sites and that cross-resistance between them is unlikely. The implications of these findings for resistance management for Vip3A are outlined.