Identification and sex-biased profiles of candidate olfactory genes in the antennal transcriptome of the parasitoid wasp Cotesia vestalis.

Cotesia vestalis (Hymenoptera: Braconidae) is an endoparasitoid wasp that attacks larvae of the diamondback moth, Plutella xylostella (Linnaeus), one of the most important pests of cruciferous plants in the world. This natural enemy has been used to control populations of P. xylostella. To more fully understand the molecular mechanisms of olfactory reception in C. vestalis, the transcriptomes of male antennae, female antennae, and mixed female and male legs were systematically analyzed, and the chemosensory genes were identified. A total of 253 olfactory genes, including candidates of 158 odorant receptors (ORs), 12 ionotropic receptors (IRs), 48 gustatory receptors (GRs), 22 odorant binding proteins (OBPs), 11 chemosensory proteins (CSPs), and two sensory neuron membrane proteins (SNMPs), were systematically identified and subjected to sequence and phylogenetic analysis. Then, the differentially expressed genes (DEGs) within female and male antennae were analyzed to obtain expression information on the candidate olfactory genes at the transcriptional level. The expression levels of 25 ORs, nine OBPs, eight GRs, and three IRs were significantly different between male and female antennae. Our results provide valuable information for further studies on the chemoreception mechanisms in C. vestalis, to ultimately improve the pest control measures by using natural enemies.