Application Abstract: Based on the theory of population genetics,this study focus on the genetic stucture of some important grasshoppers in China by using the biochemistry and molecular methods shch as RAPD,AFLP and allozyme techniques.The main results are as follows:(1)The study of population structure in some grasshoppers by using the allozyme techniques and some molecular markers such as RAPD,AFLP.The specimens collected more than ten provinces in China,including Oxya chinensis and Locust migratoria manilensis,the results studied the population genetics in these grasshoppers and showed these genetic markers could be used to reveal the relationships and their genetic structure among the species and the polulations.(2)The study of biochemical mechanisms of pesticide resistance in some pest grasshoppers.The results showed that the increasing insecticide selection pressure was attributed to the decreased insecticide sensitivity in some field populations in Locust migratoria manilensis and Oxya chinensis.Increased general esterases activities were associated with less sensitivity to these pest grasshoppers.(3)On the basis of population genetic structure and divergence of Oxya chinesis,this study examined the relationship of the allozyme genotype and the differential acute mortality of Oxya chinensis.The results suggested that the correlations between the allozyme genotype and toxic effects of pesticides.This correlation upon further confirmations is potentially applicable in monitoring the dynamic changes of allozyme genotypes of the grasshopper species as a pesticide resistance biomarker of Oxya chinenses.We have cooperation research with Kansas State University.The 31 research papers have been published in this research,and 5 Doctors and 3 Masters theses achieved.