Technical Direction of Plant Health, Instituto Colombiano Agropecuário - ICA, Bogotá, Colombia.
Department of Agronomy, Universidad de Pamplona, Pamplona 543057, Colombia.
J Econ Entomol. 2024 Jun 10;117(3):1095-1105. doi: 10.1093/jee/toae082.
In the Americas, transgenic crops producing insecticidal proteins from Bacillus thuringiensis Berliner (Bt, Bacillales: Bacillaceae) have been used widely to manage fall armyworm (FAW, Spodoptera frugiperda [J.E. Smith]). As resistance to Cry1 single-gene Bt maize (Zea mays L.) rapidly evolved in some FAW populations, pyramided Bt maize hybrids producing Cry1, Cry2, or Vip3Aa proteins were introduced in the 2010s. We examined field-evolved resistance to single- and dual-protein Bt maize hybrids in 2 locations in southeastern Brazil, where plant damage by FAW larvae far exceeded the economic threshold in 2017. We collected late-instar larvae in Cry1A.105 + Cry2Ab and Cry1F maize fields and established 2 FAW populations in the laboratory. The F1 offspring reared on the foliage of Bt and non-Bt maize plants (Cry1A.105 + Cry2Ab and Cry1F) showed neonate-to-adult survival rates as high as 70% for both populations. There was no significant difference in the life-table parameters of armyworms reared on non-Bt and Bt maize foliage, indicating complete resistance to Cry1A.105 + Cry2Ab maize. Larval survival rates of reciprocal crosses of a susceptible laboratory strain and the field-collected populations indicated nonrecessive resistance to Cry1F and a recessive resistance to Cry1A.105 + Cry2Ab maize. When relaxing the selection pressure, the armyworm fitness varied on Cry1A.105 + Cry2Ab and non-Bt maize; the resistance was somewhat stable across 12 generations, without strong fitness costs, although one of the lines died confounded by a depleted-quality, artificial rearing diet. To our knowledge, this is the first report documenting the practical resistance of FAW to a pyramided Bt crop. We discuss the implications for resistance management.
在美洲，转Bt 基因作物（苏云金芽孢杆菌 Berliner，芽孢杆菌目：芽孢杆菌科）被广泛用于防治秋粘虫（草地贪夜蛾，Spodoptera frugiperda [J.E. Smith]）。由于一些秋粘虫种群对 Cry1 单基因 Bt 玉米（Zea mays L.）的抗性迅速进化，21 世纪 10 年代引入了生产 Cry1、Cry2 或 Vip3Aa 蛋白的复合 Bt 玉米杂交种。我们在巴西东南部的两个地点检测了秋粘虫对单和双蛋白 Bt 玉米杂交种的田间抗性，2017 年秋粘虫幼虫对作物的损害远远超过了经济阈值。我们在 Cry1A.105+Cry2Ab 和 Cry1F 玉米田收集了晚期幼虫，并在实验室建立了 2 个秋粘虫种群。在 Bt 和非 Bt 玉米植株（Cry1A.105+Cry2Ab 和 Cry1F）叶片上饲养的 F1 后代的成虫存活率高达 70%，两个种群均如此。在非 Bt 和 Bt 玉米叶片上饲养的秋粘虫的生命表参数没有显著差异，表明对 Cry1A.105+Cry2Ab 玉米完全抗性。对敏感实验室品系和田间采集种群进行的正反交幼虫存活率表明，对 Cry1F 具有非隐性抗性，对 Cry1A.105+Cry2Ab 玉米具有隐性抗性。当放松选择压力时，秋粘虫在 Cry1A.105+Cry2Ab 和非 Bt 玉米上的适应性不同；经过 12 代，抗性相对稳定，没有明显的适应成本，尽管其中一个品系因耗尽质量的人工饲养饲料而死亡。据我们所知，这是第一个记录秋粘虫对复合 Bt 作物实际抗性的报告。我们讨论了这对抗性管理的影响。
