Studies on the spider community and its relation with Nilaparvata lugens (BPH)in four kinds of single rice cropping fields were carried out in Nanjing area,Jiangsu Province.The results showed that the spider community consisted of 10 families and 21 species,in which Erigonidium graminicolum,Ummeliata insecticeps,Pirata subpiraticus were the dominants.The species richness and diversity of the chemical control field were lower than that of the biological control fields,whereas the evenness became high...