Abstract: The codling moth (Cydia pomonella), a globally invasive pest affecting fruit trees, has now spread to 195 districts and counties across nine provinces and municipalities in China, which poses a significant threat to the apple, pear, and other fruit tree industries. In recent years, the advent of comparative genomics has offered novel perspectives and methodologies for investigating the genomic evolution and adaptive mechanisms of invasive species. In this study, we selected seven globally key invasive insect species, including the codling moth (Cydia pomonella), and seven closely related non-invasive insect species. We identified 2,324 single-copy orthologous genes, among which 110 genes exhibited significantly higher evolutionary rates in invasive species compared to non-invasive species. Additionally, 336 genes in invasive species displayed signs of positive selection, and these genes are involved in physiological processes such as thermogenesis and metabolic rate regulation. Our analysis of the expansion and contraction of orthologous genes and Treefam gene families between invasive and non-invasive species revealed that three orthologous gene families and 18 Treefam gene families were significantly expanded in invasive species. These expanded gene families are primarily associated with material and energy metabolism, as well as environmental adaptation. Furthermore, the number of P450 gene families in the genomes of invasive species was more than that in non-invasive species. This study utilizes comparative genomics analysis methods to elucidate common molecular characteristics in the genomic evolution of invasive insect species like the codling moth. These findings provide important theoretical support for understanding the invasion mechanisms and establishing control strategies of invasive pests.

Key words: Cydia pomonella, invasive insects, comparative genomics, invasion mechanisms, molecular evolution