Studies On Genetic Diversity And Differentiation In Fall Webworm (Hyphantria Cunea) Population And Its Influence Factors

As the major forestry pest insects in China, fall webworm (Hyphantria cunea Drury) with high speed proliferation resulting in serious economic loss. Therefore, fall webworm was designated one of six major forest pests and diseases of prevention and control with State Forestry Administration. In-depth study of genetic diversity, genetic variation and its influencing factors in invasive fall webworm population was significant.This study, by use of SSR technique, examined the genetic structure and divergence among the 5 natural populations of the fall webworm collected from different areas in Cangzhou, Shijiazhuang, Qinhuangdao, Dandong and Yantai. Base on the amplification bands, using POPGENE software, genetic diversity and genetic similarities were analyzed. Besides, cluster analysis were analyzed on all the individuals of fall webworm by NTSYS PC-22.10. The principle component analysis was analyzed between the genetic diversity, genetic distance within populations and influencing factors.This test has developed a set of optimized response Simple Sequence Repeats (SSR), which provides a powerful tool for investigation of genetic diversity and genetic variation of 5 fall webworm populations. 10 primer combinations with good repeatability,stability and polymorphism were screened from 35 SSR primers combinations of fall webworm relative families to amplified by PCR on 180 DNA samples of 5 fall webworm populations, 60 polymorphism sites were gained.Shannon′index shows highest genetic diversity in Cangzhou population and lowest genetic diversity in Shijiazhuang population, which is identical with Nei′s index.The genetic diversity of fall webworm is very abundant, but there is relatively low inter-population genetic differentiation while most resided within the different populations. Generally, the genetic variation between populations is certainly related with the high activity range,host,annual precipitation and etc.Genetic distance is foundation of genetic diversity of species, reflecting the research groups of phylogenetic, describing the genetic structure and divergence between species, explaining the distance of the relationship of each species. Using UPGMA methods cluster analyze to fall webworm populations of different invasion of colonization in China , the population in Dandong and Yantai were divided in the first time and clustered together, followed by the populations of Qinhuangdao, Cangzhou, finally, they were clustering with the population of Shijiazhuang which differentiate at the last time. Thus it can be seen that the population of Shijiazhuang had a unique clear and had an obvious genetic differences between the differentiation of the time sooner or later, so it is the main factor dividing the sooner or later of time affect the degree of population differentiation.Principle component analysis by DPS V7.05 software in fall webworm populations of different geographical areas shows genetic diversity,divergence and the influence factors, the important factors are that latitude,longitude,plain ratio of annual precipitation,the source of invasion and time of invasion.