不同害虫管理措施梨园的天敌群落多样性

通过田间试验和系统调查，研究了北京地区不同害虫管理措施梨园的天敌群落结构。调查发现了主要天敌6目，18科，25种，树冠捕食性天敌多，而地表寄生性天敌多。梨园捕食和寄生性天敌种类分别为76%和24%。整个生育期喷施农药3次的试验梨园树冠优势捕食性天敌数量显著大于喷药次数超过8次的常规梨园，试验梨园地表寄生性天敌数量略大于或显著大于常规梨园。试验梨园中天敌总个体数是常规梨园1倍以上，化学药剂施用次数与梨园天敌个体数量呈负相关。分析显示，试验梨园树冠天敌群落多样性指数和均匀性指数显著大于常规梨园，而天敌群落丰富度和优势度指数没有明显差异。研究结果对提倡生物防治、减少化学农药的使用以保护梨园天敌提供了部分实践依据。

Biodiversity of Natural Enemies in Pear Orchards as Affected by Pest Management Methods

Community structure of natural enemies in the pear orchards treated with different pest management was investigated in Dazhong orchards, Beijing. The natural enemies, including 25 principal species belonging to 18 families, 6 orders were indentified. Much more predators and parasitoids were found in the tree crown and surface ground, respectively. Predator and parasitoid species accounted for 74% and 26% of the total natural enemies, respectively. Number of predators collected from the tree crown in the experimental orchards treated with pesticides for three times was significantly higher than that in the conventional orchards received chemical pesticides above 8 times, population size of parasitoids obtained from surface ground in the experimental orchards was also bigger than that in the conventional orchards. The total number of natural enemies in the experimental orchards was more than that in the conventional orchards. Population size of natural enemies decreased with more times of chemical pesticide spraying. Shannon index and Pielou index of the natural enemy community from tree crown of the experimental orchards were obviously bigger than those of the conventional orchard, but the species richness index and dominant index showed no significant differences between the experimental and the conventional orchards. These results provided practical evidences for the impacts of chemical pesticides and biological agents on the biodiversity of natural enemy.