Identification and preliminary characterization of chemosensory-related proteins in the gall fly, Procecidochares utilis by transcriptomic analysis

Background: Chemoreception is critical for insect behaviors such as foraging, host searching and oviposition, and finding mating partners. The process of chemoreception is mediated by a series of proteins, including odorant-binding proteins (OBPs), gustatory receptors (GRs), odorant receptors (ORs), ionotropic receptors (IRs), chemosensory proteins (CSPs) and sensory neuron membrane proteins (SNMPs). The tephritid stem gall fly, Procecidochares utilis Stone, is a type of egg parasitic insect, which is an effective biological control reagent for the invasive weed Ageratina adenophora in many countries. However, the study of molecular components related to the olfactory system of P. utilis has not been investigated. Here, we report the developmental transcriptome (egg, first-third instar larvae, pupae, fame and male adult) of P. utilis using next-generation sequencing technology and identified the major chemosensory related genes.Results: In this study, a total of 133 chemosensory genes in P. utilis transcriptomes were identified by bioinformatics analysis, including 40 OBPs, 29 GRs, 24 ORs, 28 IRs, 6 CSPs, and 6 SNMPs in P. utilis. The sequences of these candidate chemosensory genes were confirmed by BLAST, and phylogenetic analysis was performed. The expression profiles of all candidate genes at different developmental stages were analyzed by differentially expressed genes (DEGs) analysis and then the expression profiles of the OBPs in the seven developmental stages were confirmed by real-time quantitative RT-PCR (qPCR). The results showed that the expression of candidate OBP genes across different developmental stages was consistent with the differentially expressed genes (DEGs) analysis using the fragments per kilobase per million fragments (FPKM) value.Conclusions: A large number of chemosensory genes were identified. This study will provide a significant contribution to the molecular mechanism of chemoreception and help advance the use of P. utilis as biological control agents.