Abstract: 【Aim】 This study aims to acquire microsatellite loci available for studying the population genetics of the oriental armyworm, Mythimna separata in China and to further uncover the genetic diversity of its geographical populations from a molecular perspective. 【Methods】 Based on microsatellite markers which had been previously reported in public and  the simple sequence repeats (SSRs) from our laboratory transcriptome of M. separata, the stability of amplification and polymorphism of these microsatellite loci were analyzed based on 200 individuals sampled in seven geographical populations from Henan, Shaanxi and Shanxi in China. The PCR products of SSRs were labeled fluorescently and scanned automatically. 【Results】 Seven microsatellite loci were amplified stably in samples of seven geographical populations of M. separata and possessed high polymorphism. The allele richness (Ar) of the seven microsatellite loci was between 4.167 and 12.402, the average observed heterozygosity (Ho) and expected heterozygosity (He) were 0.640 and 0.752, respectively, and the polymorphic information content (PIC) ranged from 0.547 to 0.884. The seven loci had null allele and deviated from Hardy.Weinberg equilibrium. No significant linkage disequilibrium existed in pairwise loci. 【Conclusion】 Seven microsatellite loci were successfully screened from seven geographical populations of M. separata from Henan, Shaanxi and Shanxi, and they show high polymorphism among these geographical populations and can be used in genetic structure research of this insect. In addition, frequent gene flow occurs in these populations, which prevents population differentiation caused by genetic drift. Moreover, fairly low even no pairwise population differentiation occurs in these populations.

Key words: Mythimna separata, microsatellite marker, amplifying stability, genetic diversity, genetic differentiation, gene flow