刈割苜蓿助迁天敌对棉田棉蚜种群动态的影响研究

在棉苜间作模式下比较研究了刈割与非刈割苜蓿(Medicago sativa L.)对棉花(Gossypium spp.)田几种主要捕食性节肢动物和棉蚜(Aphis gossypii Glover)种群动态的影响,目的在于评价适时刈割苜蓿、助迁天敌对棉蚜的控制效应。试验区每隔4行棉花间作1行50cm宽的紫花苜蓿带,当棉田棉蚜种群数量逐渐增高时,分别于6月、7月2次刈割紫花苜蓿并搁置原地,迫使苜蓿带内的捕食性天敌转移到邻近的棉田中;设非刈割苜蓿处理为对照。结果表明:刈割苜蓿后棉田内天敌种群的个体数、物种丰富度和多样性均较非刈割苜蓿处理区有明显的增加,其中,多异瓢虫(Adonia variegata(Goeze))、星豹蛛(Pardosa variegata L.Koch)、中华草蛉(Chrysopa sinica Tjeder)、小花蝽(Orius minutus(Linn.))的种群数量分别增长120.4%,100.8%,61.0%和7.2%。刈割苜蓿处理区的棉蚜种群数量比非刈割区下降了80.7%。在棉苜间作区,适时刈割苜蓿、助迁天敌转移至邻近棉田,有助于棉蚜的控制。

Evaluating Alfalfa Cutting As a Potential Measure to Enhance Predator Abundance of Aphis gossypii (Homoptera: Aphididae) in Cotton-alfalfa Intercropping System

The effects of alfalfa-cutting and non alfalfa-cutting on the population dynamics of Aphis gossypii Glover(Homoptera: Aphididae) and several species of arthropod predators were investigated in cotton-alfalfa intercropping patterns of north-western China.The objectives of this study were to evaluate the practicality of alfalfa-cutting as a management technique to enhance arthropod predator abundance of A.gossypii.Plots consisted of 50-cm alfalfa strips intercropped with four-row cotton strips.Population density of A.gossypii was gradually increased in cotton,cutting alfalfa twice on June and July forcing some groups of predators to migrate into adjacent cotton fields from alfalfa.Individual number,species richness,and diversity of predators were higher in alfalfa-cutting treatments than that in non-cutting treatments.The population density of Adonia variegata(Goeze)(Coleoptera: Coccinellidae),Pardosa variegata L.Koch(Araneae: Lycosidae),Chrysopa sinica Tjeder(Neuroptera: Chrysopidae) and Orius minutus(L.)(Hemiptera: Anthocoridae) increased 120.4%,100.8%,61.0% and 7.2% in alfalfa-cutting treatments over that in non-cutting treatments.Meanwhile,the population density of A.gossypii in alfalfa-cutting treatments decreased 80.7% more than in non-cutting treatments.This indicates that alfalfa-cutting induces predator immigration into adjacent cotton fields and helps control cotton aphids.This study provides cotton growers a potential cultural management technique for A.gossypii while conserving predators.