Limited Gene Flow among Cydia pomonella (Lepidoptera: Tortricidae) Populations in Two Isolated Regions in China: Implications for Utilization of the SIT

Codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), a highly invasive species, recently became established in the Hexi Corridor, which is a long narrow passage area with many oases surrounded by deserts and tall mountains in Gansu province, China. The corridor is an important temperate fruit growing region in northwestern China as well as a natural barrier to prevent C. pomonella from invading other fruit growing areas of the country. Since the codling moth was firstly reported, pome fruit damage in this corridor has been severe. The sterile insect technique (SIT) is considered a possible effective control tactic for integration in a future area-wide integrated pest management (AW-IPM) program against C. pomonella in the corridor. Knowledge of population genetics and more specifically of genetic differentiation and gene flow patterns may be important for developing AW-IPM strategies that include the SIT. In the current study, we collected C. pomonella samples from 8 populations distributed across 2 adjacent regions in the Hexi corridor that are geographically separated by stone deserts and high mountains. Eight microsatellite loci were used to investigate the genetic diversity, structure and differentiation of these 8 populations. Significant genetic differentiation was found between populations of each of the 2 regions, whereas populations within each region showed a similar genetic structure, demonstrated by higher Nm and lower FST values for population pairs within the same region than in pairs between the regions. Our findings indicate limited gene flow of C. pomonella between the 2 regions, which suggests that SIT can be implemented to control the pest in the Hexi Corridor of China.