Abstract:

【Objective】 This paper was aimed to discuss the effects of intercropping aromatic plants on the interaction of the dominant pest and natural enemies in pear orchard. 【Method】 Intercropping Mentha haplocalyx (Briq.var. piperascens Malinvaud), Tagetes patula L., Ocimum basilicum L. and natural grass in pear orchard were taken as four treatments and clean tillage was as control. Based on the test for the composition and dynamic changes of the arthropod community in each treatments of pear orchard, the dominant pests and natural enemies groups in each intercropping plot were systematically studied by principal component analysis, niche theory and gray correlation degree theory. 【Result】 The results showed that the trend of the dynamic changes of the dominant pests individual number was similar with that of natural enemies in the different plots of pear orchard. In the annual growth cycle of pear tree the individual number of the dominant pests in the plots of intercropping aromatic plants was significantly less than that of clean tillage plots, but the individual number of the dominant natural enemies was opposite. Compared treatment plot with the control plots, the groups of the dominant pests and natural enemies which played a leading role were different, but relatively concentrated in some varieties of the arthropod community. The dominant pests and natural enemies in the plots of the intercropping aromatic plants had a wider breadth of temporal niche than that in the clean tillage plots, and the temporal niche of the dominant natural enemies was evidently wider than that of the dominant pests. In the meantime, intercropping the aromatic plants could increase the niche overlap index of the dominant natural enemies, such as ladybugs, syrphids and their pests. It showed better following performance and more effective control in interaction of the dominant natural enemies to the dominant pests. Further more by the gray correlation analysis we found that the same pests has different predators in different intercropping plots, so the relationship of the dominant pest and natural enemies in the aromatic plants intercropping plots appear in many relationships【Conclusion】 Intercropping aromatic plants could play promotion role in reducing pest number, increasing natural enemy number and regulating the relationship between the dominant pests and natural enemies in pear orchard.

Key words: pear orchard, intercropping aromatic plants, pest and natural enemies, interaction