棉苜间作棉田天敌群落结构与动态及其对棉蚜的控制效应

The structure and dynamics of natural enemy community and controlling effect against Aphis gossypii in cotton-alfalfa intercrop fields

采取不同的棉苜间作方式,研究了棉苜间作棉田天敌群落结构及种群动态规律、棉蚜与天敌的消长动态,以及棉苜间作对棉田蚜虫的控制效应。与常规单种棉田相比,间作苜蓿棉田内的瓢虫、蜘蛛、草蛉种群数量大幅度增长,尤以每隔1膜间作75cm苜蓿带处理区为甚,分别增长了318.0%、120.9%和79.6%。间作或邻作苜蓿的棉田天敌群落的物种丰富度、丰富度指数及多样性指数均高于常规单种棉田,表明间作和邻作苜蓿带并适时刈割,可以提高棉田内天敌群落的丰富度和多样性。刈割苜蓿带对棉田棉蚜及瓢虫类、蜘蛛类和草蛉类天敌的数量动态影响较大。在棉蚜上升初期刈割苜蓿带,使棉田内瓢虫类、蜘蛛类和草蛉类天敌数量急剧上升,棉蚜数量大幅下降,从而有效地控制了棉田棉蚜的暴发。

The community structure and population dynamics of natural enemy, the dynamics of Aphis gossypii and natural enemy and the control effect against Aphis gossypii in cotton-alfalfa intercrop fields were studied using different cotton-alfalfa intercropping methods. The results showed that population density of ladybirds, spiders and lacewings had increased rapidly in cotton-alfalfa intercrop fields. The population density of ladybirds, spiders and lacewings had respectively increased 318.0%, 120.9% and 79.6% in intercropping fields of 75 cm-wide alfalfa belt within 1.6 m-wide cotton belt. The species richness, richness index and diversity of natural enemy community were higher in cotton-alfalfa intercropping or neighbor crop field than that of in normal cotton field. This implied that natural enemy community abundance and diversity in cotton field could be increased by intercropping and neighbor crop and cutting alfalfa belt at proper time. Cutting alfalfa belt could affect the population dynamics of ladybirds, spiders and lacewings. Cutting the alfalfa belt during the A. gossypii population increasing period, the population density of ladybirds, spiders and lacewings had been increased and A. gossypii had been decreased rapidly, as a result, it could control the outbreak of A. gossypii in cotton fields effectively.