BACKGROUNDThe sunflower looper, Rachiplusia nu (Guenée), evolved resistance to the insecticidal protein Cry1Ac expressed in soybean and emerged as an important soybean pest in Brazil, requiring the application of insecticides for their control. Here, we characterized the susceptibility of Brazilian populations of R. nu to several insecticides and developed diagnostic concentrations for a proactive insect resistance management (IRM) program.RESULTSGeographically distinct populations of R. nu from Brazil showed a small amount of variation in susceptibility to 15 growth regulator‐, muscle‐, nerve‐ and respiration‐action insecticides, presenting resistance levels ≤6.2‐fold those of a susceptible population. In contrast, field populations of R. nu showed 11‐ to 31‐fold higher resistance to flubendiamide (muscle‐acting) and bifenthrin (nerve‐acting) than did the susceptible population, suggesting the presence of low to moderate resistance levels. The diagnostic concentration of each insecticide established in the current study caused >98% mortality against field populations of R. nu.CONCLUSIONSIn general, field populations of R. nu from Brazil showed a small amount of variation in susceptibility and low levels of resistance to major insecticides commonly used for their control. The estimated diagnostic concentrations defined here are recommended for use in a proactive IRM program for monitoring the resistance of R. nu to insecticides. © 2024 Society of Chemical Industry.

中文翻译：

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巴西 Rachiplusia nu（鳞翅目：夜蛾科）种群对杀虫剂的易感性和确定诊断浓度，以实施主动耐药性管理计划


背景向日葵弯钩虫 Rachiplusia nu （Guenée） 对大豆中表达的杀虫蛋白 Cry1Ac 产生了抗性，并在巴西成为一种重要的大豆害虫，需要使用杀虫剂来控制它们。在这里，我们描述了巴西 R. nu 种群对几种杀虫剂的敏感性，并为主动抗虫管理 （IRM） 计划开发了诊断浓度。结果来自巴西的 R. nu 种群在地理学上不同的种群对 15 种生长调节剂、肌肉、神经和呼吸作用杀虫剂的敏感性存在少量变化，表现出≤易感种群的 6.2 倍的耐药性水平。相比之下，R. nu 的田间种群对氟苯二胺（肌作用）和联苯菊酯（神经作用）的抵抗力比易感人群高 11 至 31 倍，表明存在低至中度抵抗水平。当前研究中确定的每种杀虫剂的诊断浓度导致 R. nu 田间种群的死亡率 >98%。结论一般来说，来自巴西的 R. nu 田间种群在易感性上表现出少量变化，并且对通常用于控制其的主要杀虫剂的抗性水平较低。此处定义的估计诊断浓度建议用于主动 IRM 计划，以监测 R. nu 对杀虫剂的耐药性。© 2024 化工学会.