棉蚜密度对瓢虫集团内捕食作用的影响

Effects of Cotton Aphid Density on the Intraguild Predation among Three Ladybeetles(Coleoptera: Coccinelildae)

以华北棉田3种常见瓢虫——异色瓢虫、龟纹瓢虫和七星瓢虫为对象,依次在室内和田间条件下研究了不同棉蚜密度对瓢虫种间集团内捕食作用的影响。结果显示,室内条件下,随着棉蚜密度的上升,一种瓢虫幼虫对另一种瓢虫卵的捕食量呈下降趋势。与不提供棉蚜的对照相比,提供20、200头棉蚜的处理的捕食量分别平均降低56.5%、92.6%。田间罩笼试验显示出了相似规律,每株蚜量为50、200头时,捕食量较对照(没有棉蚜)平均降低42.0%、56.9%。结果表明,猎物棉蚜的存在能有效降低3种瓢虫之间的集团内捕食作用;棉蚜密度越高,这种趋势越明显。

The study investigated the influence of the densities of extraguild prey, cotton aphid Aphis gossypii, on the intraguild predation among three common coccinellids, Harmonia axyridis, Propyleajaponica and Coccinella septempunctata in North China. The indoor experiment showed that the predation of coccinellid eggs decreased with the increase of the cotton aphid density. With the supplement of 20 and 200 aphids, the predation averagely decreased by 56.5% and 92.6% respectively compared to that without aphid prey. The field cage experiment indicated the similar trend. When the aphid density increased from 0 to 50 per plant, the egg predation averagely decreased by 42.0%, and that decreased by 56.9% with 200 aphids. The existence of cotton aphid significantly relieves the intraguild predation among these above three coccinellids, and the effect is augmented with the increasing prey aphid density.