苹果园地面植被的优化组合对害螨和天敌群落组成的影响

苹果园种植紫花苜蓿，为捕食性天敌提供了适宜的生存环境和补充猎物，使苹果园天敌数量增加，叶螨种群下降，夏至草是苹果园杂草的优势种，该杂草可为果园前期提供天敌生存所需的花粉，花密和猎物，使东亚小花蝽发生时间早，发育速度快，将有益杂草夏至草引入果园和紫花苜蓿搭配，可弥补单纯紫花苜蓿对天敌早期增殖的不足，夏至草与紫花 苜蓿的比例变化，影响苹果园节肢动物物种数量，当夏至草的覆度大于25％时，对地面植被和苹果树冠捕食于敌种群数量最为有利。

Effects of Different Ration of Cover Crop on Community Composittion of Pest Mites and Natural Enemies in Apple Orchards

Alfalfa planted between the rows of apple trees either provides enough foods or protects habitats for predators,while the number of natural enemies increases, the number of the pest mites decrease.The white flower lagopsis is a dominant weed species in apple orchards.O.Sauteri occur early and developmental rate increase,because the white flower lagopsis can provid pollen,nectar as foods,and attract more insects as prey for predators.The number of predators in apple orchards occur more often in the treatment of alfalfa with white flower lagopsis than that in the treatment of alfalfa without white flower lagopsis.The different ratio of white flower lagopsis and alfalfa affects the population density of arthropods.The density of predators on the cover crops and on the apple trees is benefited with the coverage of white flower lagopsis more than 25% in the orchard.