Relationship Between The Arthropod Community In The Desert Transitional Zone And The Natural Enemies And Pests In The Near Cotton Field

A systematical investigation was carried out in desert transitional zone and near cotton field in Shache County, Xinjiang from April to October, 2004. The results were concluded as follows:1. The total of 385 species of arthropods, including 13 species of pests, 150 species of predators, 60 species of parasitoids, 162 species of neural arthropods were collected in the desert transitional zone. The total of 88 species of arthropods, including 15 species of pests,47 species of predators, 13 species of parasitoids, 13 species of neural arthropods were collected in cotton field.2. The desert transitional zone was species source of natural enemies of cotton field, but desert transitional zone was not species source of pests in cotton field. Most of neutral arthropods of desert transitional zone were not relationship with the neutral arthropods of cotton field. As supplementary food, the neutral arthropods of desert transitional zone played an important role for the natural enemies.3. Similarity indices were examined in different groups, descending sorts of groups were pests, spiders, total community, predators, neutral arthropods, parasitoids. From cotton field to three desert habitats, the comparison of similarity indicated the similarity indices of natural enemies and pests of near cotton field was more than that of natural enemies and pests of far cotton field, the comparison of the similarity indices of neutral arthropods was opposing to the former.4. At the first stage of cotton growth, before the food web of cotton field set up, the plant louses, leafhoppers as the food for natural enemies in the desert transitional zone. In the middle stage of cotton growth, there are plenty species and number of arthropods in all habitats. The structure of food web was very complex. At the last stage of cotton growth, natural enemies of cotton field moved to desert transitional zone, food web became simply. The food web fluctuation of desert transitional zone-cotton field showed the phase of few-many-few.5. The research about niche declared in the same time dimension, the chrysopidae and spiders occupied more spatial niche, bollworms and Tetranychus dunhuangensis occupied more spatial niche, as did the desert leafhoppers and Miridae. Time and spatial niche overlaps of parasitoids and desert aphids, chrysopidae and desert mites, ladybird beetles, syrphoidae and aphid.gossypii were more than others.