Department of Entomology, Texas A&M University, College Station, TX, 77843-2475, USA.
Southern Insect Management Research Unit, USDA-ARS, Stoneville, MS, 38776, USA.
Sci Rep. 2020 Apr 3;10(1):5867. doi: 10.1038/s41598-020-62748-8.
The corn earworm, Helicoverpa zea, is a major target pest of the insecticidal Vip3Aa protein used in pyramided transgenic Bt corn and cotton with Cry1 and Cry2 proteins in the U.S. The widespread resistance to Cry1 and Cry2 proteins in H. zea will challenge the long-term efficacy of Vip3Aa technology. Determining the frequency of resistant alleles to Vip3Aa in field populations of H. zea is critically important for resistance management. Here, we provided the first F screen study to estimate the resistance allele frequency for Vip3Aa in H. zea populations in Texas, U.S. In 2019, 128 H. zea neonates per isofamily for a total of 114 F families were screened with a diagnostic concentration of 3.0 μg/cm of Vip3Aa39 protein in diet-overlay bioassays. The F screen detected two families carrying a major Vip3Aa resistance allele. The estimated frequency of major resistance alleles against Vip3Aa39 in H. zea in Texas from this study was 0.0065 with a 95% CI of 0.0014-0.0157. A Vip3Aa-resistant strain (RR) derived from the F screen showed a high level of resistance to Vip3Aa39 protein, with a resistance ratio of >588.0-fold relative to a susceptible population (SS) based on diet-overlay bioassays. We provide the first documentation of a major resistance allele conferring high levels of Vip3Aa resistance in a field-derived strain of H. zea in the U.S. Data generated from this study contribute to development of management strategies for the sustainable use of the Vip3Aa technology to control H. zea in the U.S.
玉米穗虫，Helicoverpa zea，是美国转 Cry1 和 Cry2 蛋白 Bt 玉米和棉花中杀虫 Vip3Aa 蛋白的主要靶标害虫。H. zea 对 Cry1 和 Cry2 蛋白的广泛抗性将挑战 Vip3Aa 技术的长期功效。确定 H. zea 田间种群中 Vip3Aa 抗性等位基因的频率对于抗性管理至关重要。在这里，我们提供了第一个 F 筛选研究，以估计美国德克萨斯州 H. zea 种群中 Vip3Aa 的抗性等位基因频率。2019 年，用 3.0μg/cm 的 Vip3Aa39 蛋白在饮食覆盖生物测定中对每个同家族的 128 个 H. zea 幼虫进行了总共 114 个 F 家族的筛选。F 筛选检测到两个携带主要 Vip3Aa 抗性等位基因的家族。本研究估计德克萨斯州 H. zea 对 Vip3Aa39 的主要抗性等位基因频率为 0.0065，95%CI 为 0.0014-0.0157。从 F 筛选中衍生的 Vip3Aa 抗性品系（RR）对 Vip3Aa39 蛋白表现出高水平的抗性，基于饮食覆盖生物测定，抗性比（RR/SS）大于 588.0 倍。我们提供了美国田间衍生的 H. zea 菌株中存在高水平 Vip3Aa 抗性的主要抗性等位基因的第一个证明。本研究产生的数据有助于制定可持续使用 Vip3Aa 技术控制美国 H. zea 的管理策略。
