小麦收割对新疆北部集约化棉区主要天敌昆虫种群数量的影响

于2009年6—8月小麦成熟至收割期对新疆北部奎屯垦区124团集约化棉区进行了调查,通过扫网法采集了棉区麦田和棉田的昆虫,并对其种群数量进行了统计分析。结果表明:随着小麦逐渐成熟,麦田中的天敌昆虫数量持续下降;当小麦全部收割后,麦田中只有极少数天敌昆虫生存。而与麦田相邻的棉田中的天敌昆虫数量在小麦收割后迅速上升,平均百网虫量达到59.23头,高于对照组连片棉田(平均百网虫量15.33头);小麦的收割比例与棉田天敌昆虫的种群数量存在显著正相关关系(P<0.05),4类主要天敌昆虫(草蛉科、姬蜂科、瓢虫科、食蚜蝇科)种群数量变化趋势之间没有显著差异。小麦收割会驱使失去生境的天敌昆虫转移进入相邻的棉田,姬蜂科、瓢虫科、食蚜蝇科等活动能力强的天敌昆虫类群更容易进入新的生境,而活动能力相对较弱的类群(草蛉科)则难以转移至棉田中。深入研究集约化棉区麦田与棉田中天敌昆虫的库源关系,将有助于集约化农业体系的进一步发展。

Influence of wheat harvesting on populations of the main natural enemies of cotton pests in northern Xinjiang

This study was carried out during the mature and harvesting stage of wheat in an intensive cotton belt in northern Xinjiang in 2009. The sweeping method was used to collect insects from wheat and cotton fields after which the abundance of insects was recorded and analyzed. The abundance of natural enemies continuously declined as wheat matured and only a few survived in wheat fields after all wheat plants had been harvested. Conversely, numbers of natural enemies increased rapidly in adjacent cotton fields after wheat harvest （59.23 individuals per 100 sweeps） , which was higher than in control fields （ 15.33 individuals per 100 sweeps）. A significant positive correlation between the wheat harvest ratio and the abundance of natural enemies in adjacent cotton fields was found but there were no significant seasonal trends in the abundance of 4 main groups of these （Ichneumonidae, Coccinellidae, Syrphidae, and Chrysopidae）. Natural enemies of cotton pests that live in wheat fields may be forced to move to adjacent cotton fields when wheat is harvested. Further research on the sink-source relationship of natural enemies in the intensive cotton belt is important to improve the future sustainability of agriculture in this region.