Cytochrome P450 monooxygenases play a key role in pest resistance to insecticides by detoxification. Four new P450 genes, CYP6AS160, CYP6AS161, CYP4AB73 and CYP4G232 were identified from Solenopsis invicta. CYP6AS160 was highly expressed in the abdomen and its expression could be induced significantly with exposure to fipronil, whereas CYP4AB73 was not highly expressed in the abdomen and its expression could not be significantly induced following exposure to fipronil. Expression levels of CYP6AS160 and CYP4AB73 in workers were significantly higher than that in queens. RNA interference-mediated gene silencing by feeding on double-stranded RNA (dsRNA) found that the levels of this transcript decreased (by maximum to 64.6%) when they fed on CYP6AS160-specific dsRNA. Workers fed dsCYP6AS160 had significantly higher mortality after 24 h of exposure to fipronil compared to controls. Workers fed dsCYP6AS160 had reduced total P450 activity of microsomal preparations toward model substrates p-nitroanisole. However, the knockdown of a non-overexpressed P450 gene, CYP4AB73 did not lead to an increase of mortality or a decrease of total P450 activity. The knockdown effects of CYP6AS160 on worker susceptibility to fipronil, combined with our other findings, indicate that CYP6AS160 is responsible for detoxification of fipronil. Feeding insects dsRNA may be a general strategy to trigger RNA interference and may find applications in entomological research and in the control of insect pests in the field.

细胞色素 P450 单加氧酶通过解毒在害虫对杀虫剂的抗性中起关键作用。从Solenopsis invicta中鉴定出四个新的 P450 基因，CYP6AS160、CYP6AS161、CYP4AB73和CYP4G232。CYP6AS160在腹部高表达，暴露于氟虫腈可显着诱导其表达，而CYP4AB73在腹部不高表达，暴露于氟虫腈后不能显着诱导其表达。CYP6AS160和CYP4AB73的表达水平工人的比例明显高于皇后区。通过以双链 RNA (dsRNA) 为食的 RNA 干扰介导的基因沉默发现，当它们以CYP6AS160特异性 dsRNA 为食时，该转录物的水平下降（最大至 64.6%）。与对照组相比，喂食 ds CYP6AS160的工人在暴露于氟虫腈 24 小时后死亡率显着升高。喂食 ds CYP6AS160的工人降低了微粒体制剂对模型底物对硝基苯甲醚的总 P450 活性。然而，非过表达的 P450 基因CYP4AB73的敲低不会导致死亡率增加或总 P450 活性降低。CYP6AS160的敲低效应关于工人对氟虫腈的敏感性，结合我们的其他研究结果，表明CYP6AS160负责氟虫腈的解毒。喂养昆虫 dsRNA 可能是触发 RNA 干扰的一般策略，并可能在昆虫学研究和田间害虫控制中找到应用。