Identification of odorant receptor protein genes in two Cephid stem borers (Hymenoptera: Cephidae) by high-throughput sequencing

Insects are well adapted organisms to the terrestrial life on Earth. The evolution of the odorant receptor family is one of the causes underpinning this remarkable adaptation. Odorant receptors (ORs) sense aromas in the environment and cause the insect to respond. The ability of phytophagous insects to detect odor signals from their hosts is crucial for mating, oviposition, and feeding. The family of odorant receptor genes in Cephidae, pest on some economically important plants, is little understood. Bioinformatic tools were used to analyze the genomic data of the two pest species, Syrista parreyssii (Spinola, 1843) (Hymenoptera: Cephidae) (a rose pest) and Pachycephus smyrnensis J.P.E.F. Stein, 1876 (Hymenoptera: Cephidae), (a poppy pest), to determine their odorant receptors. The whole genome sequencing of P. smyrnensis collected in Sivas in 2020 was performed by next generation sequencing and short reads of S. parreyssii genome were obtained from previous studies. Following bioinformatic analyses, 67 and 82 putative odorant receptor genes were identified and annotated for P. smyrnensis and S. parreyssii, respectively. The ORs of these two species were found to be organized as repetitive genes in five separate clusters. No species-specific OR genes were identified in any of the investigated species. As a result, it was hypothesized that host specificity was acquired through the combined effect of multiple ORs.