Abstract:

By systematic investigation on jujube pests and their natural enemies from 1994 to 1996, the jujube pests which include 5 order, 22 families, 41 species, and natural enemies which include 8 order, 25 families, 40 species were collected. Jujube insect community was divided into 5 stages, i.e. rest period, sprout leaves period, blossom and young fruit period, developing fruit period, and fruit ripe period. Community characteristics and dominant species in each stage were analysed by the method of principal components analysis. The characteristics of population change of insect pest-natural enemies in each stage was discussed.The result of investigation showed that the number of total and natural enemy species, beneficial/hamful species number ratio, diversity index and evenness of IPM orchard were 0.4, 1.5, 11.16, 1.12, 0.67times, respectively, more than those of GC orchard. Dominant degree index or GC orchard was 3.4 times more than that of IPM orchard. The IPM orchard was in favor of controlling insect pests and protecting and utilizing natural enemies and enhancing the ability of natural coordinaton, while in GC orchard, the food web was ignored by empirical pesticide treatments, causing the significant population decrease of natural enemies, resurgence of jujube primary insect pests, and going year by year up to jujube secondary insect pests, for example, scales and mites, which have become dominant species harming jujube tree.

Key words: Jujube insect pests, IPM strategy, Principal component analysis, Community structure