Department of Entomology, Texas A&M University, College Station, TX, USA.
Southern Insect Management Research Unit, USDA-ARS, Stoneville, MS, USA.
Pest Manag Sci. 2022 Dec;78(12):5234-5242. doi: 10.1002/ps.7142. Epub 2022 Sep 7.
Crops genetically engineered to make insect-killing proteins from Bacillus thuringiensis (Bt) have revolutionized management of some pests. However, the benefits of such transgenic crops are reduced when pests evolve resistance to Bt toxins. We evaluated resistance to Bt toxins and Bt cotton plants using laboratory bioassays and complementary field trials focusing on Helicoverpa zea, one of the most economically important pests of cotton and other crops in the United States.
The data from 235 laboratory bioassays demonstrate resistance to Cry1Ac, Cry1Fa, and Cry2Ab occurred in most of the 95 strains of H. zea derived from Arkansas, Louisiana, Mississippi, Tennessee, and Texas during 2016 to 2021. Complementary field data show efficacy decreased for Bt cotton producing Cry1Ac + Cry1Fa or Cry1Ac + Cry2Ab, but not Cry1Ac + Cry1Fa + Vip3Aa. Moreover, analysis of data paired by field site and year shows higher survival in bioassays was generally associated with lower efficacy of Bt cotton.
The results confirm and extend previous evidence showing widespread practical resistance of H. zea in the United States to the Cry toxins produced by Bt cotton and corn, but not to Vip3Aa. Despite deployment in combination with Cry toxins in Bt crops, Vip3Aa effectively acts as a single toxin against H. zea larvae that are highly resistant to Cry toxins. Furthermore, Vip3Aa adoption is increasing and previous work provided an early warning of field-evolved resistance. Thus, rigorous resistance management measures are needed to preserve the efficacy of Vip3Aa against this highly adaptable pest. © 2022 Society of Chemical Industry.
通过将苏云金芽孢杆菌（Bt）产生的杀虫蛋白基因工程化，作物的虫害管理发生了革命性变化。然而，当害虫对 Bt 毒素产生抗性时，这些转基因作物的益处就会减少。我们使用实验室生物测定和互补的田间试验评估了对 Bt 毒素和 Bt 棉花植物的抗性，重点关注了美国棉花和其他作物中最重要的经济害虫之一——玉米螟。
来自阿肯色州、路易斯安那州、密西西比州、田纳西州和得克萨斯州的 95 株 H. zea 菌株的 235 次实验室生物测定数据表明，在 2016 年至 2021 年期间，这些菌株对 Cry1Ac、Cry1Fa 和 Cry2Ab 均产生了抗性。互补的田间数据表明，产生 Cry1Ac + Cry1Fa 或 Cry1Ac + Cry2Ab 的 Bt 棉花的功效降低，但产生 Cry1Ac + Cry1Fa + Vip3Aa 的 Bt 棉花的功效没有降低。此外，通过田间地点和年份配对分析数据表明，生物测定中较高的存活率通常与 Bt 棉花功效的降低有关。
这些结果证实并扩展了先前的证据，表明在美国，玉米螟对 Bt 棉花和玉米产生的 Cry 毒素普遍存在实际抗性，但对 Vip3Aa 没有抗性。尽管在 Bt 作物中与 Cry 毒素联合部署，但 Vip3Aa 仍然有效地作为单一毒素作用于对 Cry 毒素高度抗性的玉米螟幼虫。此外，Vip3Aa 的采用正在增加，之前的工作提供了田间进化抗性的早期预警。因此，需要采取严格的抗性管理措施来保持 Vip3Aa 对这种高度适应性害虫的功效。 © 2022 化学工业协会。
