Silencing of cytochrome P450 CYP6B6 gene of cotton bollworm (Helicoverpa armigera) by RNAi.

RNA interference (RNAi) induced through double-stranded RNA (dsRNA) has been used widely to study gene function in insects. In this paper we demonstrate the efficacy of RNAi in the cotton bollworm, Helicoverpa armigera. Using CYP6B6 as the target gene, which is expressed in the fat baby and midgut of the lepidopteran pest H. armigera, we constructed the vector which expressed dsRNA of CYP6B6. Northern blot analysis showed that dsRNA expressed in the Escherichia coli (HT115) was target gene. The results also showed that the gene expression level and protein expression level of H. armigera larvae fed with dsRNA expressed by E. coli were significantly lower than those of all controls, but the gene expression level was more obvious than that at the protein level; significant lethality differences were also found between HT115 bacteria containing L4440-dsC1 treatment and HT115 bacteria containing L4440 vector or CK (ddH2O) in instar larvae on 4 day when continuous feeding, 32.45% mortality was recorded in the group of feeding HT115 bacteria containing L4440-dsC1 on 10 day. Our results suggest that the RNAi pathway can be exploited to control insect pests.