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Abstract

Dynamics of insect pests and predatory enemy communities in cotton fields in north of the Huaihe River, Anhui Province.

Abstract

The dynamics of insect pest and predatory enemy communities in cotton fields in north of Huaihe River, Anhui Province (China) was studied. A total of 35 species of insect pests and 24 species of predatory enemies were found. The dominant species of insect pests were Aphis gossypii, Bemisia tabaci, Tetranychus cinnabarinus and Adelphocoris spp., and the dominant species of predatory enemies were Singa pygmaea, Propylea japonica, Pardosa t-insignita, Erigonidium graminicolum, Theridion octomaculatum [Coleosoma octomaculatum], Nabis sinoferus, Orius similis and Paederus fuscipes. Among the dominant species, the distribution ratio of S. pygmaea, Pardosa t-insignita, E. graminicolum, Theridion octomaculatum, O. similis and Paederus fuscipes on the cotton plants was: lower part > middle part > upper part. For B. tabaci and Adelphocoris spp., it was: upper part > middle part > lower part. For N. sinoferus, it was: upper part > lower part > middle part before 30 July, and lower part > upper part > middle part after 9 August. For A. gossypii, it was: upper part > lower part > middle part before 20 June, but lower part > upper part > middle part after 30 June. For Propylea japonica, it was: upper part > middle part > lower part before 10 July, but lower part > upper part > middle part after 20 July. Tetranychus cinnabarinus mainly existed in the lower part of the cotton plant in the prophase and then moved up. The evenness of the communities was relatively low during the early development stage of the cotton plant, but increased gradually during the middle development stage and declined eventually during the late development stage. The change trend of the enemy community concentration was inversely related to its evenness. During the middle development stage of cotton, the community was most diverse. The species community diversity and evenness index had significant relationship with the guild community diversity; the correlation coefficient was 0.9904.