Department of Entomology, Texas A&M University, College Station, TX 77843, USA.
USDA Agricultural Research Service, Stoneville, MS 38776, USA.
Toxins (Basel). 2021 Sep 2;13(9):618. doi: 10.3390/toxins13090618.
Evolution of resistance by pests can reduce the benefits of crops genetically engineered to produce insecticidal proteins from (Bt). Because of the widespread resistance of to crystalline (Cry) Bt toxins in the United States, the vegetative insecticidal protein Vip3Aa is the only Bt toxin produced by Bt corn and cotton that remains effective against some populations of this polyphagous lepidopteran pest. Here we evaluated resistance to Vip3Aa using diet bioassays to test 42,218 larvae from three lab strains and 71 strains derived from the field during 2016 to 2020 in Arkansas, Louisiana, Mississippi, Tennessee, and Texas. Relative to the least susceptible of the three lab strains tested (BZ), susceptibility to Vip3Aa of the field-derived strains decreased significantly from 2016 to 2020. Relative to another lab strain (TM), 7 of 16 strains derived from the field in 2019 were significantly resistant to Vip3Aa, with up to 13-fold resistance. Susceptibility to Vip3Aa was significantly lower for strains derived from Vip3Aa plants than non-Vip3Aa plants, providing direct evidence of resistance evolving in response to selection by Vip3Aa plants in the field. Together with previously reported data, the results here convey an early warning of field-evolved resistance to Vip3Aa in that supports calls for urgent action to preserve the efficacy of this toxin.
害虫的抗药性进化可能会降低转 Bt 基因作物的收益，因为在美国，鳞翅目害虫对 Cry 型 Bt 毒素的广泛抗性，导致 Bt 玉米和棉花产生的唯一 Bt 毒素 Vip3Aa 对这种多食性鳞翅目害虫的一些种群仍然有效。在这里，我们使用饮食生物测定法评估了 42218 头幼虫对 Vip3Aa 的抗性，这些幼虫来自三个实验室品系和 2016 年至 2020 年期间在阿肯色州、路易斯安那州、密西西比州、田纳西州和德克萨斯州田间获得的 71 个品系。与测试的三个实验室品系中最不敏感的 BZ 相比，田间衍生品系对 Vip3Aa 的敏感性从 2016 年到 2020 年显著下降。与另一个实验室品系 TM 相比，2019 年从田间获得的 16 个品系中有 7 个对 Vip3Aa 具有显著抗性，最高抗性达 13 倍。与非 Vip3Aa 植物衍生的菌株相比，Vip3Aa 植物衍生的菌株对 Vip3Aa 的敏感性显著降低，这直接证明了田间选择导致了对 Vip3Aa 的抗性进化。结合以前报道的数据，这里的结果传达了对田间 中 Vip3Aa 抗性进化的早期预警，这支持了迫切需要采取行动以保护这种毒素功效的呼吁。
