中文摘要：

为进一步明确细胞色素P450CYP687、细胞色素b，（cytochrome b5，Cyt-b，）和细胞色素P450还原酶（cytochrome P450 reductase，CPR）在棉铃虫Helicoverpa armigera（Htibner）对拟除虫菊酯类药剂抗性中的作用，通过RNA干扰技术沉默了抗氰戊菊酯棉铃虫中3种组分的基因，并测定基因沉默后高效氯氰菊酯对棉铃虫的毒力变化。结果显示，经单个CYP687或CYP687与CPR、Cyt-b，基因的双链RNA注射处理后12-48h，棉铃虫幼虫死亡率在19．4％-92．5％之间，明显高于空白对照处理的10．47％-62．87％；高效氯氰菊酯对基因沉默后幼虫的LD50值随着时间的延长而逐渐下降，12—48h的LD50值在0．97-2．97μg／头之间，而空白对照处理为2．27-3．57μg／头。研究表明，细胞色素P450CYP687，或CYP687与CPR、Cyt-b5基因的沉默，可提高高效氯氰菊酯对抗性棉铃虫的毒力，进一步证明了CYP687、CPR和Cyt-b，在棉铃虫对菊酯类药剂抗性中起着重要作用。

英文摘要：

To further clarify the role of cytochrome P450 CYP6B7, cytochrome b5 （ Cyt-b5 ） and cyto- chrome P450 reduetase （CPR） in a Handan fenvalerate-resistant strain of Helicoverpa armigera （ HD- FR）, the genes of the three components were silenced with RNA interference （RNAi） strategies, and the toxicity of beta-cypermethrin against H. arm@era was assessed. The results showed that the mortalities of the double-stranded RNA （dsRNA）-injected larvae of H. armigera were 19.4% -92.5%, which were significantly higher than those of the control （ 10.47% - 62.87% ）. The LDs0 values of beta-cyper- methrin to the dsRNA-injected larvae were 0.97 - 2.97 μg/larva, while those of the control were 2.27 - 3.57 μg/larva during a 12 - 48 h period, and the LD50 values decreased as the exposure time to beta- eypermethrin increased. The present study indicated that silencing of CYP6B7 alone or together with CPR and/or Cyt-b5 genes increased the toxicity of beta-cypermethrin against the larvae of fenvalerate-resistant strain of H. armigera, further suggesting that CYP6B7, CPR and Cyt-b5 played crucial roles in the resist- ance of H. armigera to pyrethroids.