Abstract: Athetis lepigone is a newly recorded insect pest of summer corn seedlings, which was first found in Hebei province in 2005 and broke out on a large scale in Hebei, Henan, Shandong, Shanxi, Anhui and Jiangsu in July, 2011. In order to explore its outbreak mechanisms at the population level, we analyzed the genetic diversity of A. lepigone populations from four provinces of China using mitochondrial cytochrome oxidase subunit Ⅰ (mtCOⅠ) gene. The partial sequences (658 bp) of mtCOⅠ gene in 19 geographic populations of A. lepigone were sequenced and analyzed through homologous sequence alignment. We also carried out the mtCOⅠ haplotype diversity analysis and Tajima’s D test, and constructed the Neighbor-Joining (N-J) phylogenetic tree and haplotype network of COⅠ haplotypes of different populations using DnaSP 5.0 and Arlequin 3.5, respectively. The results showed that there were 17 haplotypes and 18 variable sites in the total 203 individuals. The analysis of phylogenetic tree and haplotype network based on 17 mtCOⅠ haplotypes indicated that the polymorphism of mtCOⅠ haplotypes of A. lepigone populations from Hebei province was the highest among four provinces. The haplotypes of A. lepigone populations from Henan, Shanxi and Shandong were the same as those from Hebei population. However, the results of Tajima’s D test suggested that total populations did not experience obvious expansion in recent history. These results suggest that the level of gene flow among all populations of A. lepigone is high, and there is not obvious genetic differentiation among populations.

Key words: Athetis lepigone, mtDNA COⅠ, haplotype, genetic polymorphism, geographic population