Genomic Identification and Comparative Characterization of Chemosensory Genes in Two Walnut Pests

Conogethes punctiferalis (generalist) and Atrijuglans aristata (specialist) are important pests of walnut fruits. Chemosensory genes play critical roles in host location and mating, making them promising candidates for pest management research. However, genome-wide identification of these gene families has not yet been performed for either species, and cross-species comparisons are often confounded by differences in annotation quality and methodology. Here, we employed a unified pipeline for genome annotation and gene family identification to systematically characterize the odorant receptor (OR), gustatory receptor (GR), odorant-binding protein (OBP), and chemosensory protein (CSP) genes of both species and further analyzed their physicochemical properties, chromosomal distribution, and phylogeny. Genome annotation identified 13,236 and 14,083 protein-coding genes in C. punctiferalis and A. aristata, respectively, with BUSCO completeness of 94.6% and 94.5%. We identified 121 candidate chemosensory genes in C. punctiferalis (46 ORs, 23 GRs, 32 OBPs, and 20 CSPs) and 137 in A. aristata (65 ORs, 26 GRs, 28 OBPs, and 18 CSPs). Notably, A. aristata possesses more OR genes (65) than C. punctiferalis (46). Both species possess a single conserved ORco, with three and four pheromone receptor (PR) genes in C. punctiferalis and A. aristata, respectively. Chemosensory genes were either dispersed or tandemly arrayed on chromosomes, with each family clustering into conserved functional branches. This study provides a reliable foundation for comparative chemosensory evolution studies and a catalog of candidate genes for future functional validation.