Population genetic differentiation analysis of the oriental fruit fly, Bactrocera dorsalis (Diptera: Tephritidae) based on mtDNA COI gene.
Aim: This study aims to infer the invasion routes of the oriental fruit fly, Bactrocera dorsalis Hendel in China and the invasion source of its recent introduction region. Methods: mtDNA COI (1 496 bp, 97.3% of full length) of 192 individuals of 31 populations from China, Thailand, Japan, Laos, Bangladesh and USA was sequenced. The genetic diversity of each population and genetic differentiation between populations were analyzed by DnaSP 5.0, MEGA 6.0 and Arlequin 3.5, as well as haplotype analysis. Results: High nucleotide diversity (0.00663) and haplotype diversity (0.98069) were detected overall from the 31 populations of B. dorsalis. Genetic differentiation between populations analyzed using F-statistics method revealed that lower genetic differentiation were detected between populations of China, different levels of genetic differentiation were detected between populations from China and populations from Thailand, Japan, Laos, Bangladesh and USA, and the highest genetic differentiation was detected between populations from China and populations from USA and Japan. Mantel test showed that genetic differentiation among 31 populations from China, Thailand, Japan, Laos, Bangladesh and USA bore a relation to spatial distance. (R=0.670, P<0.0001), but spatial distance was not responsible for genetic differentiation among populations from China (R=0.038, P=0.534). There was no shared haplotype among populations from China, Thailand, Japan, Laos, Bangladesh and USA. The phylogenetic tree showed that original populations from China clustered into two groups, i.e., the southwest group and the southeast group. Neutrality test and mismatch distribution analysis revealed that B. dorsalis populations had experienced a large-scale expansion. Conclusion: It is inferred that there are two main invasion routes to inland China, one is from Southeast China and the other from Southwest China, and Guangdong, Fujian, Guangxi and Guizhou are the influential invasion sources. Based on the results of genetic diversity, genetic differentiation and haplotype network, it is inferred that the main sources of B. dorsalis introduced to Anhui (Hefei) are from Fujian (Changle), Guangdong (Zhuhai) and Shanghai.