Identifying genes related to olfaction in the antennae of Samia cynthia Drury (Lepidoptera: Saturniidae) via de novo transcriptome assembly

Insect olfaction is a potential target for pest management. Antennae are the primary olfactory organs in insects and are involved in the detection of various chemical molecules, regulating several physiological processes, including feeding, reproduction, and resistance to pesticides. Samia cynthia Drury (Lepidoptera: Saturniidae) is a significant lepidopteran pest that causes severe damage to various fruit and garden tree species. The aim of this study was to provide a theoretical basis for further revealing the olfactory mechanisms, thus better exploring biological control strategies against S. cynthia by mining genes related to olfaction in the antenna of S. cynthia using de novo transcriptome sequencing. Based on de novo transcriptome sequencing, we screened 54 olfaction-related genes, including those encoding 9 odorant-binding proteins (OBPs), 32 odorant receptors (ORs), 2 chemosensory proteins (CSPs), 7 ionotropic receptors (IRs), 2 sensory neuron membrane proteins (SNMPs), and 2 gustatory receptors (GRs). Expression pattern clustering and phylogenetic analysis of those genes suggest their potential involvement in perceiving pheromones and plant volatiles, oviposition, growth, development, odor detection, and pesticide resistance. A comparative transcriptome profiling of male and female S. cynthia antennae revealed 2437 differently expressed genes (DEGs), including 1582 female-biased and 855 male-biased ones. KEGG enrichment analysis showed several DEGs, potentially associated with olfactory responses, which included octopamine receptor, rho-associated protein kinase 2, atrial natriuretic peptide receptor 1, ras GTPase-activating protein 1, and cGMP-dependent protein kinase 1. These findings provide valuable insights into olfactory mechanisms and suggest possible target genes for developing novel pest control strategies based on olfactory recognition.