Interdisciplinary Graduate Program in Smart Agriculture, Kangwon National University, Chuncheon, 24341, South Korea.
Department Biotechnology and Genetic Engineering, Faculty of Biological Science, Islamic University, Kushtia, 7003, Bangladesh; Agriculture and Life Science Research Institute, Kangwon National University, Chuncheon, 24341, South Korea.
Chemosphere. 2024 Nov;367:143623. doi: 10.1016/j.chemosphere.2024.143623. Epub 2024 Nov 6.
For over a decade, diamide insecticides have been effective against lepidopteran pests like beet armyworm, Spodoptera exigua (Hübner, 1808). However, the evolution of resistance poses a challenge to their sustainable use. We identified an I4790 M mutation in the S. exigua ryanodine receptor (RyR) gene, but its correlation with resistance varied across the field-collected Korean populations of S. exigua. RNA sequencing and differential gene expression analysis were performed to investigate other resistance mechanisms. Diamide-resistant and susceptible strains and F1 hybrids were compared by mapping RNA-seq reads to the S. exigua reference genome. CYP9A40 was identified as a critical gene in diamide resistance due to its high expression in the resistant strains. Synergist bioassays with piperonyl butoxide supported the role of P450s in diamide metabolic resistance in S. exigua. A strong positive correlation between CYP9A40 over-expression levels (up to 80-fold) and diamide LC values was obtained for field-collected populations uniformly showing a 100% frequency of the RyR I4790 M target-site resistance allele. To validate the function of CYP9A40 in diamide detoxification, we recombinantly expressed the gene and tested its ability to bind and degrade chlorantraniliprole as a substrate. The results confirmed its catalytic role in diamide metabolism. CYP9A40 has been identified and validated to confer metabolic resistance in Korean S. exigua populations. It works alongside the RyR target-site I4790 M mutation to enhance diamide resistance. These mechanisms offer insights for resistance monitoring and support insecticide resistance management programs to improve control strategies for S. exigua.
十多年来，二酰胺类杀虫剂一直是防治鳞翅目害虫（如甜菜夜蛾、斜纹夜蛾）的有效手段。然而，抗药性的进化对其可持续使用构成了挑战。我们在斜纹夜蛾的肌质网钙释放通道（RyR）基因中发现了 I4790M 突变，但该突变与抗性的相关性在韩国田间采集的斜纹夜蛾种群中存在差异。我们进行了 RNA 测序和差异基因表达分析，以研究其他抗性机制。通过将 RNA-seq reads 映射到斜纹夜蛾参考基因组，比较了二酰胺抗性和敏感品系以及 F1 杂种。CYP9A40 被确定为二酰胺抗性中的关键基因，因为它在抗性品系中的高表达。与胡椒基丁醚的协同生物测定支持了 P450s 在斜纹夜蛾二酰胺代谢抗性中的作用。对于田间采集的种群，CYP9A40 过表达水平（高达 80 倍）与二酰胺 LC 值之间存在强烈的正相关，这些种群均匀地表现出 RyR I4790M 靶位抗性等位基因的 100%频率。为了验证 CYP9A40 在二酰胺解毒中的功能，我们重组表达了该基因，并测试了其结合和降解氯虫苯甲酰胺作为底物的能力。结果证实了其在二酰胺代谢中的催化作用。CYP9A40 已被鉴定并验证可赋予韩国斜纹夜蛾种群代谢抗性。它与 RyR 靶位 I4790M 突变协同作用，增强二酰胺抗性。这些机制为抗性监测提供了见解，并支持杀虫剂抗性管理计划，以改善斜纹夜蛾的控制策略。
