Abstract:

【Objective】 The objective of the study is to discuss the genetic differentiation of the Bactrocera dorsalis (Hendel) in Chongqing region. 【Method】 One hundred and fifty-five individuals of B.dorsalis collected from 6 districts of Chongqing were divided into 6 populations and analyzed by 8 microsatellite markers to examine the genetic diversity and genetic differentiation in Chongqing region. 【Result】 A total of 51 alleles were detected at 8 loci. The range of Mean Observed Heterozygote (Ho) was from 0.1731 to 0.2958 and the range of Mean Expected Heterozygote (He) was from 0.1311 to 0.6796. The Chi-square test results argued that the 6 populations of B. dorsalis in present study did not follow with the Hardy-Weinberg Equilibrium at most loci. The analysis results of Percentage of Polymorphic Loci, Nei’s Gene Diversity and Shannon Information Index indicated that there was a high level in genetic diversity among the 6 populations of B. dorsalis. The mean Genetic Differentiation Index (FST) was 0.0777, which demonstrated that genetic differentiation mainly occurred inner-population. The utmost genetic distance (0.2367) appeared between Wulong population and Yongchuan population, meanwhile the nearest genetic distance (0.0667) occurred between Jiangjin population and Beibei population. The UPGMA phylogenetic tree showed that the 6 populations in Chongqing region clustered into two groups. Populations of Beibei, Jiangjin, Wanzhou, Xiushan, and Yongchuan merged into one group, while population from Wulong solely formed the other group.【Conclusion】 The results suggested that genetic differentiation already occurred among the 6 populations, although the degree of differentiation was low. The invasion of the oriental fruit fly in Chongqing region was at the primary stage.

Key words: Bactrocera dorsalis (Hendel)')">Bactrocera dorsalis (Hendel), microsatellite marker, genetic diversity, genetic differentiation