Spodoptera litura (Fabricius) is a widely distributed, highly polyphagous pest that can cause severe damage to a variety of economically important crops. Various populations have developed resistance to different classes of insecticides. In this study, we report on two indoxacarb-resistant S. litura populations, namely Ind-R (resistance ratio = 18.37-fold) derived from an indoxacarb-susceptible (Ind-S) population and a population caught from a field (resistance ratio = 46.72-fold). A synergist experiment showed that piperonyl butoxide (PBO) combined with indoxacarb produced higher synergistic effects (synergist ratio = 5.29) in the Ind-R population as compared to Ind-S (synergist ratio = 3.08). Elevated enzyme activity of cytochrome P450 monooxygenases (P450s) was observed for Ind-R (2.15-fold) and the Field-caught population (4.03-fold) as compared to Ind-S, while only minor differences were noticed in the activities of esterases and glutathione S-transferases. Furthermore, expression levels of P450 genes of S. litura were determined by quantitative reverse transcription PCR to explore differences among the three populations. The results showed that the mRNA levels of CYP6AE68, a novel P450 gene belonging to the CYP6 family, were constitutively overexpressed in Ind-R (32.79-fold) and in the Field-caught population (68.11-fold). CYP6AE68 expression in S. litura was further analyzed for different developmental stages and in different tissues. Finally, we report that RNA interference-mediated silencing of CYP6AE68 increased the mortality of fourth-instar larvae exposed to indoxacarb at the LC₅₀ dose level (increase by 33.89%, 29.44% and 22.78% for Ind-S, Ind-R and the Field-caught population, respectively). In conclusion, the findings of this study indicate that expression levels of CYP6AE68 in S. litura larvae are associated with indoxacarb resistance and that CYP6AE68 may play a significant role in detoxification of indoxacarb.

Spodoptera litura (Fabricius) 是一种分布广泛、高度多食性的害虫，可对多种重要经济作物造成严重损害。不同的人群已经对不同种类的杀虫剂产生了抗药性。在这项研究中，我们报告了两种抗茚虫威的斜纹夜蛾种群，即 Ind-R（抗性比 = 18.37 倍）来自茚虫威敏感（Ind-S）种群和从田间捕获的种群（抗性比 = 46.72 倍）。增效剂实验表明，与 Ind-S（增效剂比 = 3.08）相比，胡椒基丁醚 (PBO) 与茚虫威结合在 Ind-R 群体中产生更高的增效作用（增效剂比 = 5.29）。与 Ind-S 相比，观察到 Ind-R（2.15 倍）和田间捕获种群（4.03 倍）的细胞色素 P450 单加氧酶 (P450s) 的酶活性升高，而酯酶活性仅观察到微小差异和谷胱甘肽S-转移酶。此外，斜纹夜蛾P450 基因的表达水平通过定量逆转录 PCR 确定，以探索三个种群之间的差异。结果表明，CYP6AE68（一种属于 CYP6 家族的新型 P450 基因）的 mRNA 水平在 Ind-R（32.79 倍）和野外捕获种群（68.11 倍）中组成型过度表达。进一步分析了斜纹夜蛾中不同发育阶段和不同组织中的CYP6AE68表达。最后，我们报告说 RNA 干扰介导的CYP6AE68沉默增加了 LC ₅₀暴露于茚虫威的四龄幼虫的死亡率剂量水平（Ind-S、Ind-R 和野外捕获种群分别增加 33.89%、29.44% 和 22.78%）。总之，这项研究的结果表明的表达水平CYP6AE68在斜纹夜蛾幼虫与茚虫威性和CYP6AE68相关联茚虫威的解毒可能发挥显著作用。