Silencing NADPH-Cytochrome P450 reductase affects imidacloprid susceptibility, fecundity, and embryonic development in Leptinotarsa decemlineata

Abstract

ABSTRACTThe Colorado potato beetle (CPB) is a prominent insect pest of potatoes, tomatoes and eggplants all over the world, however, the management of CPB remains a challenging task for more than one hundred years. We have successfully developed bacteria-expressed dsRNA-mediated feeding RNA interference (RNAi) approach in our previous study. A critical step towards field management of CPB via feeding RNAi is to identify effective and environmentally safe target genes. NADPH-Cytochrome P450 reductase (CPR) plays a central role in cytochrome P450 action. The full length Leptinotarsa decemlineata CPR (LdCPR) cDNA was isolated from an imidacloprid resistant population. The LdCPR gene was ubiquitously expressed in all stages tested but showed an increase in expression during the early stage of embryonic development. The bacteria-expressed dsRNA-mediated feeding RNAi of LdCPR in adults caused systemic knock down expression of the gene coding for LdCPR in both adults and their eggs. Suppression of LdCPR expression increased susceptibility of imidacloprid in resistant beetles, as well as a significant decrease of fecundity in female beetles (29% less eggs/day) and the hatching rate (47%) of their eggs. These data suggest that LdCPR plays important roles in insecticide detoxification and biosynthetic pathways of endogenous compounds and may serve as an essential target to control CPB.HIGHLIGHTSHigh expression of LdCPR was observed in the egg stage.Silencing of LdCPR reduced the CPR enzymatic activities.LdCPR knockdown increased imidacloprid susceptibility.LdCPR knockdown decreased the fecundity and enhanced embryonic lethality.