Pyrethroid insecticides have been widely utilized for insect pest control. Target-site resistance is one of the major mechanisms explaining pest resistance to pyrethroids. This study quantified pyrethroid resistance and fitness cost conferred by the voltage-gated sodium channel (VGSC) M918L mutation in Rhopalosiphum padi. Six s-kdr-SS and six s-kdr-RS parthenogenetic lineages were established from the same field population and were reared in the laboratory without exposure to pesticides for more than one year. Enzyme activity analysis demonstrated that metabolic resistance had no impact on these lineages. Bioassays showed that the M918L mutation strongly affected pyrethroid efficiency, conferring moderate resistance to bifenthrin (type I) (39.0-fold) and high resistance to lambda-cyhalothrin (type II) (194.7-fold). Compared with the life table of s-kdr-SS lineages, s-kdr-RS lineages exhibited a relative fitness cost with significant decreases in longevity and fecundity. Meanwhile, competitive fitness was measured by blending various ratios of s-kdr-SS and s-kdr-SS aphids. The results indicated that M918L-mediated resistance showed a significant fitness cost in the presence of wild aphids without insecticide pressure. The fitness cost strongly correlated with the initial resistance allele frequency. This work characterized the novel s-kdr M918L mutation in R. padi, defined its function in resistance to different types of pyrethroids, and documented that the M918L-mediated resistance has a significant fitness cost.

中文翻译：

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超 kdr 突变 M918L 对 Rhopalosiphum padi（半翅目：蚜科）的拟除虫菊酯抗性和适应性成本

拟除虫菊酯类杀虫剂已广泛用于害虫防治。靶点抗性是解释害虫对拟除虫菊酯抗性的主要机制之一。本研究量化了 Rhopalosiphum padi 中电压门控钠通道 (VGSC) M918L 突变赋予的拟除虫菊酯抗性和适应性成本。从同一田间种群中建立了六个 s-kdr-SS 和六个 s-kdr-RS 孤雌生殖谱系，并在实验室中饲养超过一年而不接触杀虫剂。酶活性分析表明代谢抗性对这些谱系没有影响。生物测定表明，M918L 突变强烈影响拟除虫菊酯的效率，赋予对联苯菊酯（I 型）的中等抗性（39.0 倍）和对 λ-三氯氟氰菊酯（II 型）的高抗性（194.7 倍）。与 s-kdr-SS 谱系的生命表相比，s-kdr-RS 谱系表现出相对的适应度成本，寿命和繁殖力显着下降。同时，通过混合不同比例的 s-kdr-SS 和 s-kdr-SS 蚜虫来测量竞争适应性。结果表明，在没有杀虫剂压力的野生蚜虫存在下，M918L 介导的抗性表现出显着的适应性成本。适应度成本与初始阻力等位基因频率密切相关。这项工作以 R. padi 中的新型 s-kdr M918L 突变为特征，确定了其对不同类型拟除虫菊酯的抗性功能，并证明 M918L 介导的抗性具有显着的适应度成本。通过混合不同比例的 s-kdr-SS 和 s-kdr-SS 蚜虫来测量竞争适应性。结果表明，在没有杀虫剂压力的野生蚜虫存在下，M918L 介导的抗性表现出显着的适应性成本。适应度成本与初始阻力等位基因频率密切相关。这项工作以 R. padi 中的新型 s-kdr M918L 突变为特征，确定了其对不同类型拟除虫菊酯的抗性功能，并证明 M918L 介导的抗性具有显着的适应度成本。通过混合不同比例的 s-kdr-SS 和 s-kdr-SS 蚜虫来测量竞争适应性。结果表明，在没有杀虫剂压力的野生蚜虫存在下，M918L 介导的抗性表现出显着的适应性成本。适应度成本与初始阻力等位基因频率密切相关。这项工作以 R. padi 中的新型 s-kdr M918L 突变为特征，确定了其对不同类型拟除虫菊酯的抗性功能，并证明 M918L 介导的抗性具有显着的适应度成本。