Mitochondrial COI gene sequence-based population genetic structure of the diamondback moth, Plutella xylostella, in Korea

The diamondback moth, Plutella xylostella, known as a serious cosmopolitan pest for cruciferous plant has been subjected to the issue of study for the control of the pest. Therefore, researches on the genetic variation and population genetic structure were also of great interest, because the knowledge on these aspects were expected to provide better understanding on the aspects of field ecology. We, thus, sequenced a portion of mitochondrial COI gene (438 bp) of 86 P. xylostella collected over 11 localities in Korea to investigate the magnitude and nature of genetic variation of this species in Korea. One of the outstanding features of the species was the presence of exceptionally high numerical numbers of mtDNA haplotypes (52 haplotype), and resultantly high within-population haplotype diversity in most local populations. Analyses of phylogeny by neighbor-joining method and mismatch distribution revealed that most haplotypes are closely related to each other, but two haplotypes are distinct and excluded from the majority of haplotypes, suggesting the existence of haplotypes with divergent origin in Korea. Within-locality distribution pattern of haplotypes suggests that each Korean population can be characterized as co-existence of a large number of unique local haplotypes and a few co-occurring haplotypes with a wide distribution. Analyses of population genetic structure showed that most of the Korean populations are not genetically differentiated and, instead, a high gene flow ratio among populations is characteristic. Taken together, the nature of genetic divergence of the Korean diamondback moth populations is characterized as one that possessing high haplotype diversity, high gene flow, and a few immigrants from outside study area.