Applying four numerical methods to analyze aquatic insects diversity in rice fields

From March 6 to June 5, 1998, aquatic insects were sampled from a biologically controlled rice field (B.F.) and a chemical controlled rice field (C.F.) in Dasha town, Sihui County, Guangdong Province, P. R. China. Forty-three species of aquatic insects were collected. Four numerical methods, Jaccard^s coefficient of similarity, coefficient of difference, values of global covering and coefficient of development, were used to evaluate the pollution. The result showed that fauna in B.F. is different from those of C.F. in species richness and abundance. It is suggested that coefficient of development and global covering be more reasonable to assess the water quality of rice fields.