Abstract: The genetic structure of the four geographic populations of the Oriental migratory locust Locusta migratoria manilensis was analyzed using horizontal starch gel electrophoresis. Among 20 loci of 13 isozymes identified, the higher the percentage of polymorphic loci (P=70%－80%), the lower the observed overall heterozygosity (H_o=0.023－0.032). The result from Chi-square test for the genotype frequencies showed the genotype frequency at most loci deviated significantly from Hardy-Weinberg equilibrium except Adk-1, Gdh-1, G3pd-1 and Pgm-1 Based on F-statistics (average F_st= 0.0606), an extremely small genetic differentiation among the four populations was observed. It appeared that the long-distance migration of the locust enhanced gene flow and decreased genetic differentiation. The divergence among four populations was revealed using Nei’s genetic identity (I) and Roger’s genetic distance (D). The higher the genetic identity, the smaller the genetic distance observed between Shanxi-Linyi and Shanxi-Yongji populations (I=0.964, D=0.175), and between Jiangsu-Peixian and Henan-Zhongmou populations (I=0.957, D=0.160). The results indicated that there was a positive relationship between genetic differentiation and geographic distance.

Key words: Locusta migratoria manilensis, population, genetic differentiation, allozyme, China