Department of Plant and Environmental Sciences, Pee Dee Research and Education Center, Clemson University, Florence, SC 29506-9727, USA.
Department of Entomology, University of Georgia, Griffin, GA 30223, USA.
J Econ Entomol. 2024 Oct 14;117(5):1901-1912. doi: 10.1093/jee/toae160.
Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) has evolved resistance to insecticidal toxins from Bacillus thuringiensis (Bt) Berliner (Bacillales: Bacillaceae) expressed in genetically engineered corn, Zea mays L. This study provides an overview of field trials from Georgia, North Carolina, and South Carolina evaluating Bt and non-Bt corn hybrids from 2009 to 2022 to show changes in susceptibility in H. zea to Bt corn. The reduction in kernel injury relative to a non-Bt hybrid averaged across planting dates generally declined over time for Cry1A.105 + Cry2Ab2 corn. In addition, there was a significant interaction with planting date used as a covariate. The reduction in kernel injury remained above 80% and did not vary with planting date from 2009 to 2014, whereas a significant decline with planting date was found in this reduction from 2015 to 2022. For Cry1Ab + Cry1F corn, the reduction in kernel injury relative to a non-Bt hybrid averaged across planting dates did not vary among years. The reduction in kernel injury significantly declined with planting date from 2012 to 2022. Kernel injury as a proxy for H. zea pressure was greater in late-planted trials in non-Bt corn hybrids. Our study showed that Bt hybrids expressing Cry1A.105 + Cry2Ab2 are now less effective in later planted trials in reducing H. zea injury; however, this was not the case during the earlier years of adoption of corn expressing these 2 toxins when resistance alleles were likely less frequent in H. zea populations. The implications for management of H. zea and for insect resistance management are discussed.
玉米穗夜蛾（Helicoverpa zea）（鳞翅目：夜蛾科）已经对表达苏云金芽孢杆菌（Bt） Berliner（芽孢杆菌目：芽孢杆菌科）杀虫毒素的基因工程玉米产生了抗药性，玉米，Zea mays L. 本研究提供了 2009 年至 2022 年佐治亚州、北卡罗来纳州和南卡罗来纳州田间试验的概述，以展示玉米穗夜蛾对 Bt 玉米敏感性的变化。相对于非 Bt 杂交种，Cry1A.105 + Cry2Ab2 玉米的籽粒损伤减少率在整个种植期普遍随时间下降。此外，种植日期的使用作为协变量存在显著的交互作用。2009 年至 2014 年，与非 Bt 杂交种相比，Cry1A.105 + Cry2Ab2 玉米的籽粒损伤减少率保持在 80%以上，且不随种植日期而变化，而 2015 年至 2022 年，这种减少率随种植日期显著下降。对于 Cry1Ab + Cry1F 玉米，相对于非 Bt 杂交种，Cry1Ab + Cry1F 玉米的籽粒损伤减少率在各年份之间没有差异。与非 Bt 玉米杂交种相比，Cry1A.105 + Cry2Ab2 玉米的籽粒损伤减少率在 2012 年至 2022 年期间随种植日期显著下降。作为玉米穗夜蛾压力的替代指标，非 Bt 玉米杂交种的晚播试验中，籽粒损伤更大。我们的研究表明，在后期种植的试验中，表达 Cry1A.105 + Cry2Ab2 的 Bt 杂交种在减少玉米穗夜蛾伤害方面的效果较差；然而，在这些毒素表达玉米采用的早期，抗性等位基因在玉米穗夜蛾种群中可能不那么常见，情况并非如此。讨论了对玉米穗夜蛾管理和昆虫抗药性管理的影响。
