Data from: Assessing the role of non-cotton refuges in delaying Helicoverpa armigera resistance to Bt cotton in West Africa

Non-cotton host plants without Bacillus thuringiensis (Bt) toxins can provide refuges that delay resistance to Bt cotton in polyphagous insect pests. It has proven difficult, however, to determine the effective contribution of such refuges and their role in delaying resistance evolution. Here we used biogeochemical markers to quantify movement of Helicoverpa armigera moths from non-cotton hosts to cotton fields in three agricultural landscapes of the West African cotton belt (Cameroon) where Bt cotton was absent. We show that the contribution of non-cotton hosts as a source of moths was spatially and temporally variable, but at least equivalent to a 7.5% sprayed refuge of non-Bt cotton. Simulation models incorporating H. armigera biological parameters, however, indicate that planting non-Bt cotton refuges may be needed to significantly delay resistance to cotton producing the toxins Cry1Ac and Cry2Ab. Specifically, when the concentration of one toxin (here Cry1Ac) declined seasonally, resistance to Bt cotton often occurred rapidly in simulations where refuges of non-Bt cotton were rare and resistance to Cry2Ab was non recessive, because resistance was essentially driven by one toxin (here Cry2Ab). The use of biogeochemical markers to quantify insect movement can provide a valuable tool to evaluate the role of non-cotton refuges in delaying the evolution of H. armigera resistance to Bt cotton.缺乏苏云金杆菌（Bacillus thuringiensis，简称Bt）毒素的非棉花寄主植物，可为多食性害虫提供庇护所，以延缓其对转Bt棉花的抗性演化。然而，准确量化此类庇护所的实际贡献及其在延缓抗性演化中的作用，此前一直是学界的难题。本研究针对西非棉带（喀麦隆）三个无转Bt棉花种植的农业景观区域，采用生物地球化学标记物定量分析棉铃虫（Helicoverpa armigera）成虫从非棉花寄主向棉田的迁飞活动。研究结果显示，非棉花寄主作为成虫虫源的贡献存在空间与时间异质性，但至少等同于7.5%的喷施型非Bt棉花庇护所。然而，纳入棉铃虫生物学参数的模拟模型结果表明，若要显著延缓表达Cry1Ac与Cry2Ab毒素的转基因棉花的抗性演化，仍需种植非Bt棉花庇护所。具体而言，当其中一种毒素（此处为Cry1Ac）的浓度随季节下降时，在非Bt棉花庇护所稀缺且对Cry2Ab的抗性为非隐性遗传的模拟场景中，对转Bt棉花的抗性往往会快速演化——这是因为此时抗性主要由单一毒素（此处为Cry2Ab）驱动。利用生物地球化学标记物定量昆虫迁飞活动，可作为评估非棉花寄主庇护所在延缓棉铃虫对转Bt棉花抗性演化过程中作用的有效工具。