杭州郊区菜蚜寄生蜂初步调查

1985～1986年,在杭州东郊系统调查了13块地5种十字花科蔬菜上蚜虫的寄生性天敌和被寄生率。共发现原寄生蜂两种,即菜小脉蚜茧蜂和烟蚜茧蜂,前者寄生于桃蚜和萝卜蚜,后者仅寄生于桃蚜,寄生率大多在0～3％,很少超过10％,在蚜虫数量上升阶段寄生率一般呈下降趋势,只有在蚜虫数量迅速下降阶段才明显上升,故蚜虫数量变化受寄生蜂影响不大。共发现重寄生蜂5种,重寄生率平均约为50％,高时接近100％。表明重寄生蜂在一定程度上影响了蚜茧蜂对蚜虫的控制效能。

A PRELIMINARY INVESTIGATION OF THE PARASITES OF APHIDS ON CRUCIFEROUS VEGETABLES IN HANGZHOU

In 1985-1986, mummified aphids were regularly sampled in 13 field plots of cruciferous vegetables in the suburbs of Hangzhou to examine the parasite complex and rates of parasitization of aphids. Two primary parasites were found. They were Diaeretiella rapae, which parasitized both Myzus persicae and Lipaphis erysimi; and Aphidius gifuensis, which parasited M. persicae only. The rates of parasitization were usually 0-3%, rarely exceeded 10%. The parasitization rates generally decreased during the phase of rapid increase of aphid numbers, and showed marked increase only when aphid populations were in their final sharp decline phase. It indicated that the population changes of aphids were not substantially influenced by the parasites. Five hyperparasites were found, with 50% (highest 100%) of average parasitization of the aphidiids. The results suggested that the control efficacy of the aphidiid parasites on the host populations was, to some extent at least, adversely offset by these hyperparasites.