关键词: 烟蚜茧蜂, 麦二叉蚜, 变温, 耐寒性, 过冷却点, 能源物质

Abstract: The amount of soil microorganisms under forests has a good positive correlation with the overalllevel of soil enzyme activity.The sequence from high to low is Oak forest>Cunninghamia lanceo-late> Pinus teade forest >wasteland.The bacteria in Oak forest soil, actinomyces in wasteland.and fungi in Pinus taede forest soil show the highest ratio.Oak, Cunninghamia lanceolate and Pi-nus taede roots present a marked rhizospheric effect(R:S) on fungi and bacteria, and the effectof Pinus taede is most notable.The activities of catalase, urease, invertase, acid phosphatase,and polyphenol oxidase are stronger in rhizosphere than in non-rhizosphere。 There is a negativeeffect of Oak forest roots on urease and acid phosphatase, and of Cunninghamia lanceolate rootson polyphenol oxidese.The improving effect of forests on rhizospheric soil is Oak forest>Pinustaede forest>Cunninghamia lanceolate forest>wasteland.

Key words: Aphidius gifuensis, Schizaphis graminum, fluctuating thermal regime, cold tolerance, supercooling point (SCP), energy substance.