Abstract：
Diamondback moth (DBM, Plutella xylostella) is the most significant pest of cruciferous vegetables as they rapidly develop high-level resistance to many insecticides. Monitoring DBM susceptibility and target-site mutation frequency is essential for pest control. In this study, 10 insecticides were tested on 11 field populations. Frequencies of target-site mutations (including para, ace1, Rdl1, RyR1, and nAChRα6 genes) were estimated by pyrosequencing. Insecticides registered after 2007 for DBM control in Taiwan, i.e., spinetoram, chlorantraniliprole, chlorfenapyr, metaflumizone, and flubendiamide, showed >80% mortality toward several populations; Bacillus thurigiensis, emamectin benzoate, and chlorfluazuron showed medium to low efficacy in all populations; and tolfenpyrad and mevinphos were highly ineffective. Susceptibility to insecticides varied substantially among populations: eight out of nine populations were highly susceptible to spinetoram, but only one was susceptible to flubendiamide. Target-site mutations related to organophosphates, pyrethroids, fipronil, and diamides were detected in all populations, but there were few spinosad and spinetoram mutations. Our three-year field study demonstrated rapid efficacy loss for all insecticides tested, particularly for more toxic insecticides. Skipped-generation selection of a field DBM strain to emamectin benzoate, metaflumizone, chlorantraniliprole, and flubendiamide revealed that mortality rates dropped from 60 to 80% to <10% after 6 generations. Next-generation sequencing was performed to identify possible target gene mutations. A resistance management program that considers the instability of resistance to some chemicals and pertinent data on resistance mechanisms should be established. Identifying compounds to overcome high-frequency field DBM point mutations could be beneficial for pest control.
摘要：
小菜蛾(DBM，小菜蛾）是十字花科蔬菜中最重要的害虫，因为它们对许多杀虫剂迅速产生高水平的抗性。监测DBM易感性和靶位点突变频率对于害虫防治至关重要。在这项研究中,在11个田间种群上测试了10种杀虫剂。靶位点突变的频率（包括para，通过焦磷酸测序估计了ace1，Rdl1，RyR1和nAChRα6基因）。2007年后在台湾注册用于DBM控制的杀虫剂，即，spinetoram,chloantraniliprole,氯非那霉素,metaflumizone,和氟苯二酰胺,对几个种群显示>80%的死亡率；苏里吉芽孢杆菌，甲氨基阿维菌素苯甲酸酯，在所有人群中，氯氟隆均表现出中等至较低的疗效；tolfenpyrad和mepinphos非常无效。对杀虫剂的敏感性在人群中差异很大：九分之八的人群对spinetoram高度敏感，但只有一个人对氟苯二酰胺敏感.与有机磷酸酯相关的靶位点突变，拟除虫菊酯,氟虫腈,在所有种群中都检测到二酰胺，但是多杀菌素和多杀菌素突变很少。我们为期三年的实地研究表明，所有测试的杀虫剂的药效迅速丧失，特别是毒性更大的杀虫剂。一株大田DBM菌株对甲氨基阿维菌素苯甲酸酯的跳代选择，metaflumizone,chloantraniliprole,和氟苯二酰胺显示，6代后死亡率从60％下降到80％，下降到<10％。进行下一代测序以鉴定可能的靶基因突变。应建立考虑对某些化学品的抗性不稳定性的抗性管理计划以及有关抗性机制的相关数据。鉴定克服高频场DBM点突变的化合物对于害虫防治可能是有益的。
