Comparative Study On The Desert And Oasis Beetle Community And Cotton Fields Insect Community Of The Lower Yarkant River

Structure of Litter-layer beetle community in the landscape and insect community in cotton fields were investigated in Yarkant River Basin of Xinjiang in 2005 and 2006, and the temporal and spatial dynamic of litter-layer beetle and cotton insect community were analyzed. The influence of human acitivities (soil reclaimation, agricultural practice) on the insect community was discussed. The main conclusions were as follows:1. 1262 individuals of litter-layer beetles, belonging to 16 families and 57 species (genera), were collected during the two years, and Tenebrionidae and Carabidae were considered as common in the study area. Tenebrionidae comprised 58.72% and Carabidae 20.6% of the total in 2005. As the most abundant species in the region, Penthicicus koltzei Reitter (Tenebrionidae) took 49.45%, and Broscus semistriatus Dejean and Calosoma auropunctatum dsungaricum Gebler both counted 20.6% of total specimens, respectively.2. The individualsTenebrionidae occurred usually only in the desert, and the individuals of Carabidae were significantly more abundant in the oasis habitats. The habitats of the most abundant species were the same with the most dominant groups. The individuals Penthicicus koltzei Reitter (Tenebrionidae) occurred usually only in the desert, and the individuals Broscus semistriatus Dejean and Calosoma auropunctatum dsungaricum Gebler (Carabidae) were significantly more abundant in the oasis habitats. More individuals of Curculionidae were trapped in the forest of 30 years than in the other habitats. It was showed that the different litter-layer beetles like to live in the habitat they like to.3. There were more species of the litter-layer beetles in the island of Tamarix than the barren in the desert, we obtained 21 species and 16species inTamarix habitat, and 10 species and 12 species in desert barren in 2005 and 2006, respectively. There are more than 13 individuals per square metres of penthicicus koltzei Reitter in Tamarix habitat. So island of Tamarix is playing very important role in the desert, which protect and refuge of the insect in desert.4. We collected 47 species insect belonging to 10 orders and 31 families in cotton fields. There were more natural enemies in organic cotton fields than in control conventional cotton fields. The diversity index and the evenness index of insect community were lower but the dominance was higher compared with the control conventional cotton field. So the community stability of the organic cotton field was lower than the control conventional cotton field. Community diversity indexes of the conventional cotton field were 2.25, 2.27 in 2005 and 2006, respectively. The evenness indexes were 0.67, 0.70, respectively. The dominance were 0.15, 0.17, respectively. The diversity indexes of the organic cotton field were 2.03, 2.09 in 2005 and 2006, respectively. The evenness indexes were 0.60, 0.63, respectively. The dominance indexes were 0.20, 0.18, respectively. Only depend on nature enemies could not control effectively A. gossypii population density, It was suggested that in the production of organic agricultural cotton, spraying plant source- pesticides could be helpful to suppress A. gossypii in organic agricultural cotton fields.