Analysis and Identification of Chemosensory Genes in the Transcriptome of Adult Rhoptroceros cyatheae

Rhoptroceros cyatheae (Hymenoptera) belongs to the genus Rhopographus of Selandriidae. It mainly causes large-scale infestations during the sprouting period of Alsophila spinulosa , and is among the herbivorous insects that harm this plant.The body of R. cyatheae contains chemosensory genes that detect and transduce chemical signals related to host location, feeding, mating, and oviposition. However, to date, no reports on the chemosensory genes of R. cyatheae have been published. Thus,on the basis of a the tran-scriptome database of male and female adult individuals of R. cyatheae , a total of 30,296 unigenes were identified, with an N50 length of 3,286 bp. Through comparisons with six major public databases, namely NR, Swiss-Prot, Pfam, eggNOG, GO, and KEGG, a total of 11,109 unigenes were annotated, accounting for 36.67%. Among these, the number of unigenes annotated in the NR database was the largest, reaching 10,774, whereas the number of unigenes annotated in the KEGG database was the smallest, at 6,300. An analysis of the annotation information, 90 candidate chemosensory genes of R. cyatheae , including 11 OBPs, 10 CSPs, 6 NPC2s, 24 ORs (comprising 23 typical OR genes and 1 Orco gene), 20 IRs, 15 GRs and 4 SNMPs. A phylogenetic tree of chemosensory genes was subsequently constructed to investigate the homology between the chemosensory genes of the R. cyatheae and those of other insect species. Furthermore, 13 chemosensory genes differentially expressed between males and females, and their tissue expression profiles were verified via RT‒qPCR. These findings lay a molecular foundation for further research on the gene functions and olfactory perception mechanisms of R. cyatheae .