Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA 50011, USA.
J Econ Entomol. 2023 Apr 24;116(2):565-573. doi: 10.1093/jee/toad022.
Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a serious pest of corn and is currently managed with corn hybrids that produce insecticidal proteins derived from the bacterium Bacillus thuringiensis (Bt). Bt corn kills rootworm larvae and reduces larval feeding injury to corn roots. The Bt protein Gpp34/Tpp35Ab1, previously named Cry34/35Ab1, has been widely used in transgenic Bt corn for management of western corn rootworm, and field-evolved resistance has been found in some populations. In the United States, the refuge strategy is used to manage Bt resistance, with refuges of non-Bt host plants serving as a source of Bt-susceptible individuals, which in turn reduce the frequency of homozygous resistant individuals within a population. As such, the dominance of resistance strongly influences resistance evolution, with faster evolution of resistance when resistance is not recessive. Additionally, selection for resistance by a Bt crop leads to the accumulation of resistance alleles within refuge populations, thereby reducing the capacity of refuges to delay resistance. However, fitness costs can remove resistance alleles from refuge populations and preserve the dynamic of refuges producing Bt-susceptible genotypes. Bt-susceptible and Gpp34/Tpp35Ab1-resistant western corn rootworm were used to quantify the inheritance and fitness costs of resistance. We found that Gpp34/Tpp35Ab1 resistance was not recessive and had the accompanying fitness costs of slower developmental rate to adulthood and lower egg viability. This research will help improve insect resistance management by providing a better understanding of the risk of western corn rootworm evolving resistance to transgenic corn that produces Gpp34/Tpp35Ab1.
西方玉米根萤叶甲，Diabrotica virgifera virgifera LeConte（鞘翅目：叶甲科），是玉米的严重害虫，目前通过种植产生杀虫蛋白的玉米杂交种来防治，该蛋白来源于苏云金芽孢杆菌（Bt）。Bt 玉米可杀死根萤叶甲幼虫并减少幼虫对玉米根系的取食损伤。Gpp34/Tpp35Ab1 蛋白（以前称为 Cry34/35Ab1）已广泛用于转 Bt 玉米中防治西方玉米根萤叶甲，且在一些种群中已发现其具有田间进化抗性。在美国，采用避难所策略来管理 Bt 抗性，非 Bt 宿主植物避难所作为 Bt 敏感个体的来源，从而降低种群内纯合抗性个体的频率。因此，抗性的显性程度强烈影响抗性的进化，当抗性为非隐性时，抗性进化更快。此外，Bt 作物对抗性的选择导致避难所种群中抗性等位基因的积累，从而降低避难所延迟抗性的能力。然而，适应选择可将抗性等位基因从避难所种群中去除，并保持避难所产生 Bt 敏感基因型的动态。利用 Bt 敏感和 Gpp34/Tpp35Ab1 抗性的西方玉米根萤叶甲来量化抗性的遗传和适应成本。我们发现，Gpp34/Tpp35Ab1 抗性不是隐性的，并且具有发育速度较慢到成虫和较低的卵活力的适应成本。这项研究将通过更好地了解西方玉米根萤叶甲对产生 Gpp34/Tpp35Ab1 的转基因玉米产生抗性的风险，来帮助改善昆虫抗性管理。
