Western flower thrips (WFT) is a serious pest of vegetable crops. Feeding by adults and larvae causes severe physical crop damage and WFT also spreads viruses such as tomato spotted wilt virus (TSWV) that can wipe out entire crops. Resistance monitoring for WFT against several key registered products including spinosad in this project demonstrated that spinosad resistance is increasing in both level and abundance. To improve resistance management, a more detailed knowledge of how the WFT develops resistance to spinosad is required. For this purpose, the project focussed on resistance monitoring data, cross resistance data, resistance mechanism data, molecular genetics data, glasshouse field trial data designed to better understand spinosad resistance and improve WFT control and management.