Studies On The Dynamics Of Arthropod Communities In Cauliflower Field

In order to research of pest management and application for the non-environment damage vegetable,in this paper, in-depth investigation and analysis of autumn cauliflower fields of animal community structure and organization ,which of the county in Anhui Province and Vegetable Technology Demonstration Park ,strived to discover the traits of arthropod community in cauliflower field and enrich the theoretical foundation for IPM of pests.The arthropod total community was divided into four sub-communities: phytophage, predacious, parasitic and neutrality sub-community as to species'nutrition and predator-prey relationship. In 2007, arthropods got 18 species which belonged to 16 families, phytophage was prominent part, its relative abundance was 0.9791,dominant species was Bemisia tabaci and Spodoptera exigua and that of predacious sub-community was 0.0195, dominant species was Theridiidae; In 2008, arthropods got 38 species belonged to 30 families, phytophage was prominent part, its relative abundance was 0. 9412,dominant species was Bemisia tabaci and Spodoptera litura; and that of predacious sub-community was 0.0461, dominant species was Erigonidium graminicola.Concentration and dominance in two years were compared and the result was phytophage sub-community>total community>predacious sub-community, and result of the diversities indexes predacious sub-community >total community> phytophage sub-community; The result of the above in two years was the same, which was caused by large number of the dominant population.Caused by interaction of pest,natural enemy and climate factors, whether or not greenhouse in experimental plot, indexes of every communities fluctuated. Change tendency of diversity index in two years in total community was: low-high-low-high-low; and so did phytophage sub-community, while predacious sub-community kept in a high level all the time.The relations between diversity indexes and other ecological indexes in every community were analyzed by Path analysis in two seasons. Evenness had close relationship with diversity indexes in total community; richness,species numbers,dominant concentration,dominance all influenced diversity indexes; diversity indexes of phytophage sub-community was decided by evenness while predacious sub-community decided by number of individuals.Total community and phytophage, predacious sub-community in two years in different time were analyzed by clustering. The clustering result of the optimization partitions in the arthropod total communities in 2007 was :9.06,9.13, 11.01,11.08, 10.11,9.27,10.04,9.20, 10.18,8.30,10.25 ; which in 2008 was 9.12-919;9.26;10.03-10.10;10.18-10.25.The characteristic parameters of arthropod community and its phytophagous,predacious sub-community in cauliflower field in two years were analyzed with the method of principal component analysis. The results showed that in 2007: in the first principal component, the contribution of arthropod community, phytophagous and predacious sub-community in cauliflower was42.66%,43.44%,61.98% respectively. For the three kinds of communities, the absolute values of normalized regressive coefficient of N (number of individual), N1 (Hill diversity index), N2 (Hill diversity index) and S (species numbers) were larger, indicating that N, N1, N2 and S had greater contribution ; in 2008: in the first principal component, the contribution of arthropod community, phytophagous sub-community and predacious sub-community in soybean was 73.18%,56.35%,54.57% respectively. For the three kinds of communities, the absolute values of normalized regressive coefficient of N,N1 and N2 had greater contribution.