Community structure and its dynamics of pest, predatory and neutral insects in a jujube ecosystem.

An investigation on the insects in the jujube ecosystem in Taigu District of Shanxi Province, Northern China showed that more species and individual numbers of pest, predatory and neutral insects were found on the tree than on the ground. The ratio of the species and individual numbers of predatory and neutral insects to those of pest insects fluctuated from year to year. Homoptera, Coleoptera and Lepidoptera were the dominant groups of pest insects, while those of predatory insects were Coleopteran, Hemiptera, Diptera and Hymenoptera. The vertical distribution of the community structure of the same or different subcommunity was different in different seasons, as was the case of the same or different subcommunity in the same season. The diversity indexes of pest, predatory and neutral insects fluctuated with seasons, and the populations of predatory and neutral insects had a significant correlation (r = 0.9833, P <0.05) with the fluctuation of pest insects. There was also a significant correlation between the pest, predatory and neutral insects in different stratums of tree canopy, especially in the middle stratum of tree canopy (r = 0.9887, P <0.01).