Study On Temporal And Spatial Distribution Of Hyphantria Cunea(Drury)in Beijing Based On GS And GIS

The fall webworm Hyphantria cunea(Drury),Lepidoptera,Arctiidae,is a worldwide quarantine pest in forestry.It has also been listed as the main alien invasive organism in China.In order to clarify the distribution and explore the key influencing factors of the fall webworm in Beijing area,this study is based on the information of the population density of the fall webworm,which is provided by the Beijing forestry protection station,with the help of the software ArcGIS and GS+,we analyzed the characteristics of the semivariogram of the fall webworm population from 2008 to 2014 in Beijing area by geostatistics theory.Then,the distribution map is generated by Kriging interpolation.On the basis of the distribution map,the spatial and temporal dynamics of the fall webworm population are further analyzed,next we found out the key influencing factors of the distribution,the origin and the general diffusion route of the fall webworm that first invaded in Beijing area.The purpose of this paper is to provide a theoretical basis for the prevention and control technology of the fall webworm,and provide basic data for the construction of the resource pool of the main invasive species in China.The results showed that:there are 3 generations of the fall webworm in Beijing area,they are the overwintering generation,the first generation and the second generation.Its distribution pattern is aggregated distribution,and the populations who have greater population density,they have greater aggregation degree too.Distribution characteristics of the fall webworm:it distributes in the area below 400 meters above sea level,the trend of number is high in the east and south,low in the west and in the north,and the quantity is concentrated in Dongcheng county,Xicheng county,Haidian county,Chaoyang county,Fengtai county and other regions.The number of the fall webworm changes in Beijing is the largest number of overwintering adults in a single year.The first generation and the seeond generation of adults are less.The number of adults in a single year is declining,and the number will increase at overwintering generations of the next year,so the number of the population changes periodically.The factors affecting the distribution of the fall webworm are temperature,topography and human disturbance.The annual maximum temperature will affect the distribution of the first generation and the second generation,and the annual minimum temperature will affect the distribution of overwintering generations;and the fall webworm likes to live in low altitude areas;meanwhile the number of human population and traffic situation are the two key human disturbance factors that can causing a large moth population.This study speculated that the fall webworm invaded in Beijing probably came from a population near the border between Pinggu and Hebei province.The general route of invasion of fall webworm in Beijing area is:the source population is located at the Hebei region where is close to the Pinggu county,then the moth invaded in Pinggu county,next,it spread from the Pinggu county to the other suitable regions in Beijing,and the stable aggregation distribution pattern is formed under the influence of various factors finally.