LAUSR

Odorant‐degrading enzymes (ODEs) have been found in insect antennae and play a critical role in signal chemical degradation once the message is conveyed. Significant progress has been made in characterizing ODEs in a variety of pests but very little is known in their natural enemies. We have carried out an antennae‐ and sex‐specific transcriptome of Aphidius gifuensis, a natural enemy of aphid, to identify the candidate ODEs. Based on the antennae‐ and sex‐specific transcriptome, a total of 100 putative ODEs were identified including one aldehyde oxidase (AOX), four alcohol dehydrogenases (ADs), eight UDP‐glucuronosyltransferases (UGTs), 45 cytochrome P450 (P450s), nine glutathione S‐transferases (GSTs) and 40 carboxylesterases (CCEs or CXEs). Additionally, we used RT‐qPCR to determine the expression profiles of these genes in tissues of both sexes. Based on the phylogenic analysis and tissue‐expression patterns, AgifEstE4, AgifCXE3, AgifCCE4, AgifCCE7, and AgifCCE18 were suggested as key ODEs in A. gifuensis. In addition, the female or male specifically enriched genes, such as AgifCCE17, AgifEstB1, AgifCYP18a1, AgifUGT2C2, were also considered to involve in the chemosensory processing in A. gifuensis. This study not only identified the candidate ODEs in A. gifuensis but also provided source for further exploration of the molecular mechanisms of chemical signal transductions in A. gifuensis, as well as other hymenopteran species.