| The investigation of insect community was conducted from 2001 to 2002 in the peach orchards of Licheng District in Jinan, Shandong province. The predacious function of major natural enemies to Myzus persicae and Hyalopterus amygdali and the effect of the pesticides used in peach orchard on the major natural enemies were studied in Laboratory. The main conclusions are as follows:1. The insect species were examined in the peach orchards. In 2001, there were sixty-three species in the peach orchards, which included thirty species of insect pests and thirty-three species of natural enemies. The phyllophagous insects were dominant in the insect community, and the other phytophagous insects were rare.2.The species composition in the insect community and the relative abundance of each group were studied in the peach orchards. The insect pests such as Erythroneura sudra, Lyonetia clerkella, Hyalopterus amygdali, Myzus persicae, Tetranychus viennensis and Didesmococcus koreanus were main species. The main natural enemies were Ladybird beetles, lacewings and spiders.3.The population dynamics of the major insect pests, such as Hyalopterus amygdali, Myzus persicae and Didesmococcus koreanus, and their natural enemies were investigated.4.The numerical characteristics of insect community in the peach orchards, such as ecological dominance, species richness, community diversity and evenness were analysiszed. The structure characteristics of the insect community in the peach orchards were as follows: (1) the ecological dominance of insect community maintained higher level on the whole. (2) the dominants of phytophagous insects were highest. (3) the community diversity and evenness were lower generally in most part of the growing season. These characteristics indicated that the insect community structure was unstable and unreasonable in77the peach orchards. The main factors influencing community diversity were vegetation community around the peach orchard, behavior of insect pests, application of insecticides and climatic condition.5.The spatial and temporal niches of the major insect pests and natural enemies in the peach orchards were studied. The result indicated:The one-dimensional spatial niche of the pests and natural enemies in a temporal sequence from April to July were dynamic. Their niche breadths varied with the lapse of time. The niche overlaps of some pests and natural enemies were high, which showed that the natural enemies had close sympatry in space with pests.The temporal niche breadths of the pests and natural enemies varied in sizes, which indicated the occurences of them existed unevenness in the temporal sequence. The niche overlaps of some pests and their natural enemies were high, which showed that the natural enemies had close synchrony with the pests. The sympatry in space and the synchrony in time indicated that these natural enemies had high efficiency to control their preys.Both horizontal and vertical spatial niches breadths of the pests and natural enemies were also quite high. There were no remarkable differences of resource-utilizing in different direction.6.The spatial distributions of the major insect pests such as Empoascanara sudra, Hyalopterus amygdali and Myzus persicae were studied. The result indicated that their spatial distribution fitted negative binomial distribution and belonged to the aggregated pattern. And the feasible research methods about those three pests were worked out.7. Studied on the predatory functional responses and searching efficiency of major natural enemies (Harmonia axyridis, Coccinella septempunctata.Chrysopa septem punctatd) to the Hyalopterus amygdali and Myzus persicae showed that these natural enemies had high efficiency to control aphids.8. The effect of the pesticides used in the peach orchard on the major natural enemies was studied. As a result, the insect growth regulators were secure for Ladybird beetles and lacewings, but the other pestisides such as organophosphorous and synthetic pyrethroid...
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