The Dynamic Research Of Insect Community And Dominance Population In Shaanxi Luochuan Apple Orchard

We have a preliminary understanding on the composition of insect community in Luochuan apple orchard through investigation.At the same time,we analyse the insect communities and population dynamics from the edge of time and space on the structure,the results show that: Ground arthropod in Luochuan apple orchard are composed of two classes,14 orders,more than 60 familys,100 species, including pest are 8 orders,48 familys,more than 80 species, the natural enemies are 7 orders,14 famielys,24 species. Insect community has higher advantage, prominently dominant species, fierce competition between species,so the community is in a prerious state. The change of the pests and the nutural enemies number are different in different habitats,the ratio of benefit harm is also different,the ratio is 1:7.51 in young apple orchard, 1:45.67 in adult orchard.The trends of the insect community is the same with the time between young apple orchard and adult orchard. The peak age in interplanting young apple orchard is longer than in adult apple orchard,the number is larger in a tree,and the number is different between different interplanting orchards. Insect community was divided into different stages using optimal segmentation method.we analyse the number of insect in crown's different directuions,the number of insects is that: central> upper> lower, South> East> North> West, the medial> lateral, the difference between East,South,West,North and the medial and lateral was not Signifintly; the difference between upper and central, central and lower are signifint; the difference between the upper and the lower was not signifint. Insect community was divided into three different regions in the 20 cluster's position using the Cluster system.The number of different populations changed different with time.The number of Spiraea aphid reached the peak in early July,the population number of Lithocolletis ringoniella Mats larvae index-based rose in late September, Tetranychus viennensis Zacher reached the peak in early September. The relative abundance of different species was different in different investigate time.The number of dominant species and difference were different in different directions,Aphis citricola Van der Goot: South> East> North> West, Lithocolletis ringoniella Mats: lower>middle>upper,North> East> West> South,the inside> outside,Tetranychus viennensis Zacher:upper>central>lower,East> West> North> South,the inside> outside. Three dominant species'differences was not signifint,in the horizontal direction, differences in the vertil direction is not the same. Three dominant species in the distribution of Apple's crown belonged to gathered distribution and was related to the density, was attractive between each individual, and we could see individual groups,the aggregation of three dominant species were different in different investigate time.The population was divided intodifferent regions in apple's position on the crown by hierarchial clustering,and the niche width and the index of niche overlap were different in different population orientations. The most wide extent of spatial niche was 2.6566 of Tetranychus viennensis Zacher in vertil orientation, the maximum extent of spatial niche index was between Tetranychus viennensis Zacher and Aphis citricola Van der Goot. In the horizontal direction, Tetranychus viennensis Zacher distributed at east and west, Lithocolletis ringoniella Mats distributed east,west and north, Aphis citricola Van der Goot distributed east and south, between Tetranychus viennensis Zacher and Lithocolletis ringoniella Mats was the max extent of spatial niche index. The wide extent of spatial niche was Lithocolletis ringoniella Mats, between Tetranychus viennensis Zacher and Lithocolletis ringoniella Mats was the max extent of spatial niche index with time.The parasitic rate was different at different orientations in relationship between natural enemies and pests .The parasitic rate of yangling was higher than luochuan,Yangling was 45.27%, Luochuan was 27.04%.The hightest parasitic rate was 93.42% in yangling and luochuan was 49.33% in 20 orientations of tree. Parasitic wasps uniform distributed in the crown of fruit trees, individuals were exclusive mutually, and the host of "toeing the line of effect" was not obvious.