The industry resistance management plan for Bacillus thuringiensis (Bt) cotton is underpinned by resistance monitoring. This project is developing molecular techniques to identify the diversity and relative frequencies of Bt resistance alleles in Helicoverpa armigera and H. punctigera with a view to developing a cost-effective, faster technique for resistance monitoring. While the primary aim of the molecular techniques is to monitor resistance frequencies and detect new forms of resistance, the ability to test greater numbers of moths more easily will also inform what resistance looks like regionally and seasonally and enable elements of the resistance management plan to be tested.