Abstract: 【Aim】 The purpose of this study is to clarify the population genetic variation, population genetic structure, population genetic differentiation and gene flow of the small brown planthopper, Laodelphax striatellus, in Northeast China. 【Methods】 Nine pairs of microsatellite primers were used to sequence and analyze 375 samples of L. striatellus collected from 15 geographical populations in Northeast China, and the genetic diversity, genetic differentiation, gene flow and population genetic structure of  these geographical populations were analyzed using GeneAlex 6.51, GENEPOP 4.0.9 and STRUCTURE 2.3.4 based on the nine microsatellite (SSR) molecular markers. 【Results】 The average number of effective alleles per locus was 6.898 among the 375 individuals of L. striatellus assayed. In general, the genetic diversity of different geographical populations of L. striatellus was high (mean observed heterozygosity Ho=0.548; mean expected heterozygosity He=0.582), and the gene flow between different populations was low (Nm=0.660). The results of UPGMA clustering tree, PCoA and STRCTURE analysis showed that L. striatellus populations in Northeast China were divided into two groups: populations from Jilin (JL) and Shenyang (SY2012, SY2013 and SY2014) were clustered into one group, and the remaining populations into another group. The AMOVA analysis showed that the genetic variation of L. striatellus was mainly from within the population (87%), and the inter-population variation level was low (13%). 【Conclusion】 The genetic diversity of L. striatellus in Northeast China is relatively high, different geographical populations have a certain degree of genetic differentiation, the gene exchange is low and a certain population genetic structure exists.

Key words: Laodelphax striatellus, microsatellite, genetic diversity, genetic structure; gene flow