Molecular characterization and gene functional analysis of Dicer-2 gene from Nilaparvata lugens (Hemiptera: Geometroidea)

Nilaparvata lugens (Stal) (Hemiptera: Geometroidea), a serious rice pest in many countries of Asia, causes a great loss in rice production every year. RNA interference (RNAi) is a powerful technology for gene function study in insects and a potential tool for pest control. As a core component of RNAi pathway, Dicer-2 (Dcr-2) protein determines the production of small interfering RNA (siRNA) and is crucial for the efficiency of RNAi. In this study, the full-length complementary DNA (cDNA) of N. lugens Dcr-2 (NlDcr-2) was first cloned and analyzed, and then the RNAi experiment was conducted to explore the function of NlDcr-2 gene. The complete Dcr-2 cDNA of N. lugens was 4 971 bp in length with an open reading frame (ORF) of 1,656 amino acids. Phylogenetic and protein domain analysis showed that the predicted NlDcr-2 protein was similar to Tribolium castaneum. In the RNAi experiment, the messenger RNA level of NlDcr-2 was significantly reduced by NlDcr-2 double-stranded RNA (dsRNA) (dsDcr-2). Fifty-five per cent decrease of NlDcr-2 was found after 4 days of unremitting feeding. No significant effect was observed on the development of N. lugens after dsRNA ingestion.