RNA interference-mediated knockdown of some genes involved in digestion and development of Helicoverpa armigera

Helicoverpa armigera is a significant agricultural pest and particularly notorious for its resistance to many types of common insecticides. RNA interference (RNAi) is a mechanism of post-transcriptional gene silencing and trigged by double-strand RNA (dsRNA), has become a widely used reverse genetics and potent tool for insect pest control. In this study, the effect of ingestion and injection delivery methods of dsRNA related two important enzyme genes, α-amylase ( HaAMY48, Ha-AMY49 ) and juvenile hormone esterase ( Ha-JHE ), were examined on growth and development of H. armigera . After 24, 48, 72 and 96 h of feeding bioassay, significant down regulation was observed about; 56, 68, 78, 80.75% for HaAMY48 , 60, 70, 86.5 and 96.75%, for Ha-AMY49 and 14, 27.5, 23 and 31.7% for Ha-JHE , respectively. The results for injection assay was 61.5, 71.5, 74 and 95.8% for Ha-AMY48 ; 70, 88, 91.5 and 97.7% for Ha-AMY49 and 22, 61, 75 and 74% for Ha-JHE after 24, 48 and 72 h of last injecting, respectively. Larvae that treated with dsRNA, fed or injected, lost more than half of their weight. 50% mortality in treated larvae was observed in the case injection bioassay with ds Ha-JHE and 59% of larvae that fed of dsRNA-treated cubes survived. Ds Ha-AMY48 and 49 have significant mortality, but mixing of them is more effective in both bioassays. Injection bioassay has a potent inhibitory effect on α-amylase-specific activity about more than 87% in treated larvae with mix of ds Ha-AMY48 and 49 . Adult malformation percent was evaluated for feeding (28, 35.5 and 43% for Ha-AMY48, 49 and Ha-JHE , respectively) and injection bioassay (23, 42 and 29% for Ha-AMY48, 49 and Ha-JHE , respectively). All these finding suggest that Ha-AMY48, Ha-AMY49 and Ha-JHE can be new candidates to scheming effective dsRNAs pesticide for H. armigera control.