Abstract:  【Aim】 The diamondback moth, Plutella xylostella L., is one of the most important dispersal pests of cruciferous vegetables worldwide, and it is featured by the interrelated metapopulations of “source-sink” between overwintering regions (OR) and seasonally breeding regions (SBR) in China. This study aims to investigate the spatiotemporal dynamics of genetic variation in P. xylostella populations in China and to further uncover the effect of dispersal behavior on its regional outbreaks. 【Methods】 The genetic variation of P. xylostella populations was investigated based on four independent datasets of 1 567 COI sequences of P. xylostella at different sampling time in China. Each dataset was classified into three groups, i.e., OR populations, SBR populations and populations sampled at a given sampling time (ST). The genetic diversity, genetic differentiation, haplotype similarity and demography history of these populations were investigated. 【Results】 Genetic variation analysis of P. xylostella populations based on COI sequences revealed a comparable genetic variation between OR and SBR populations sampled at the same time. Although the unstable haplotype frequency in SBR led to a great genetic differentiation of SBR-involved populations, COI haplotypes in SBR populations either could be found in OR populations sampled at the same time or showed a limited difference (<2 bp) from the COI haplotypes in OR populations. The haplotype frequency of SBR populations varied greatly among different years. Variation of genetic differentiation between SBR populations was the highest in all population combinations, while that between ST populations was the lowest. Haplotype analysis at different sampling time showed a similar pattern in nucleotide mismatch distributions, and the similar haplotype pattern consists of several dominant haplotypes. 【Conclusion】 Our results indicate that dispersal is the major factor in shaping the genetic variation of SBR populations of P. xylostlla, and P. xylostella populations tend to exhibit a temporal stability and interrelation of genetic variation in different regions of China. The nature of metapopulation provides an important ecological base for understanding the seasonal dispersal of P. xylostella.

Key words: Plutella xylostella, spatiotemporal scale, genetic variation, dispersal, overwintering region, seasonally breeding region