Insect ryanodine receptors (RyRs) are the targets of diamide insecticides. Two point mutations G4946E and I4790M (numbering according to Plutella xylostella, PxRyR) in the transmembrane domain of the insect RyRs associated with diamide resistance have so far been identified in three lepidopteran pests, P. xylostella, Tuta absoluta and Chilo suppressalis. In this study, we identified one of the known RyR target site resistance mutations (I4790M) in a field‐collected population of Spodoptera exigua. The field‐collected WF population of S. exigua exhibited 154 fold resistance to chlorantraniliprole when compared with the susceptible WH‐S strain. Sequencing the transmembrane domains of S. exigua RyR (SeRyR) revealed that the resistant WF strain was homozygous for the I4743M mutation (corresponding to I4790M in PxRyR), whereas the G4900E allele (corresponding to G4946E of PxRyR) was not detected. The 4743M allele was introgressed into the susceptible WH‐S strain by crossing WF with WH‐S, followed by three rounds of backcrossing with WH‐S. The introgressed strain 4743M was homozygous for the mutant 4743M allele and shared about 94% of its genetic background with that of the recipient WH‐S strain. Compared with WH‐S, the near‐isogenic 4743M strain showed moderate levels of resistance to chlorantraniliprole (21 fold), cyantraniliprole (25 fold) and flubendiamide (22 fold), suggesting that the I4743M mutation confers medium levels of resistance to all three diamides. Genetic analysis showed diamide resistance in the 4743M strain was inherited as an autosomal and recessive trait. Results from this study have direct implications for the design of appropriate resistance monitoring and management practices to sustainably control S. exigua.

中文翻译：

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兰尼碱受体突变 I4743M 的鉴定及其对甜菜夜蛾（鳞翅目：夜蛾科）二酰胺类杀虫剂抗性的贡献

昆虫兰尼碱受体 (RyRs) 是二酰胺杀虫剂的目标。迄今为止，已在三种鳞翅目害虫 P. xylostella、Tuta absoluta 和 Chilo suppressalis 中鉴定出与二酰胺抗性相关的昆虫 RyRs 跨膜结构域中的两个点突变 G4946E 和 I4790M（根据 Plutella xylostella，PxRyR 编号）。在这项研究中，我们在田间收集的甜菜夜蛾种群中鉴定了一个已知的 RyR 靶位点抗性突变 (I4790M)。与易感的 WH-S 菌株相比，田间采集的甜瓜 WF 种群对氯虫苯甲酰胺的耐药性提高了 154 倍。对 S. exigua RyR (SeRyR) 的跨膜结构域进行测序显示，抗性 WF 菌株对于 I4743M 突变（对应于 PxRyR 中的 I4790M）是纯合的，而未检测到 G4900E 等位基因（对应于 PxRyR 的 G4946E）。通过将 WF 与 WH-S 杂交，然后与 WH-S 进行三轮回交，将 4743M 等位基因渗入易感 WH-S 菌株中。基因渗入菌株 4743M 是突变 4743M 等位基因的纯合子，与受体 WH-S 菌株共享约 94% 的遗传背景。与 WH-S 相比，近等基因 4743M 菌株对氯虫苯甲酰胺（21 倍）、氰虫酰胺（25 倍）和氟虫酰胺（22 倍）表现出中等水平的耐药性，表明 I4743M 突变对所有三种二酰胺类药物均具有中等水平的耐药性. 遗传分析显示 4743M 菌株的二酰胺抗性是作为常染色体和隐性性状遗传的。