Effects of carboxylesterase gene silence on wheat aphid Sitobion avenae (Fabricius)

Multifunctional carboxylesterase (CarE) has been found in all animals, plants and microbes, and belongs to a superfamily enzyme of serine hydrolase involved in detoxification, allelochemical tolerance and some specific hormone or pheromone metabolism. Insects usually utilize carboxylesterases to detoxify xenobiotics, and positively correlated with insect resistance to some insecticides. Despite the importance of CarEs in insects, carboxylesterases and their functions in wheat aphid Sitobion avenae (Fabricius) have not been clear. In this study, a sequence that encodes a carboxylesterase protein from S. avenae (SaCarE) was sequenced and cloned. After aligning the encoded amino acid sequence of the SaCarE gene with other known CarEs of insects, we found that the CarE gene was highly conserved in insects. The SaCarE mRNA levels at different developmental stages of S. avenae were gradually increased from the first instar of nymphs to adult stage. RNAi was employed to further explore its functions, in which oral ingestion of SaCarE double-stranded RNA from the third instar nymph significantly knocked down SaCarE expression, and significantly decreased ecdysis index in S. avenae. These results indicate that SaCarE is functional in S. avenae and could serve one of the potential target genes for management of S. avenae.