Host adaptation in Cydia pomonella (Lepidoptera: Tortricidae) using microsatellite DNA markers

The codling moth (CM), Cydia pomonella (L.), is among the economically important pests of pome fruits. This moth causes tremendous crop losses worldwide annually. In the current study, 210 larvae from apple, pear, quince, and walnut orchards were collected from seven locations in Zanjan province, Iran. Four CM-specific microsatellite DNA loci, including Cyd10, Cyd11, Cyd12, and Cyd13, were analyzed by polymerase chain reaction (PCR). According to the results, the CM population sampled from quince showed the highest number of alleles per locus with the mean observed and effective allele numbers 1.75 and 1.51, respectively. The latter shows the number of alleles with equal frequencies that contributed the most to the observed heterozygosity. Also, the mean observed and expected heterozygosity for this population was 0.508 and 0.258, respectively. The increased observed heterozygosity confirms that the selection acts in favor of heterozygote genotypes. Large genetic distances were detected between the CMpopulation from quince and the populations sampled from the other host plants, the largest between quince and walnut populations. Further, amongpopulation diversity contributed the most to the insect’s genetic diversity, which was 89%. Moreover, some of the populations had a deviation from the Hardy-Weinberg equilibrium (p < 0.001). While Cyd13 locus was more polymorphic than the other tested loci, Cyd11 locus was monomorphic. These findings reveal genetic variation in C. pomonella, collected from various fruit trees, indicating differences in some phenotypes noteworthy in integrated pest management.