白蛾周氏啮小蜂可持续控制美国白蛾的研究

Studies on Utilizing Parasitoid Chouioia cunea Yang (Hymenoptera: Eulophidae) for Sustainable Control of Fall Webworm

利用白蛾周氏啮小蜂防治美国白蛾,在老熟幼虫期和化蛹初期分别放蜂1次,放蜂量为美国白蛾幼虫数量的5倍,连续放蜂防治两代美国白蛾,就可将其种群数量有效控制,使有虫株率降到1.25%,天敌的总寄生率达到92.67%。放蜂防治后连续5年,共追踪调查10代美国白蛾的发生情况,发现这种小蜂具有良好的持续控制效果。美国白蛾在防治后第2年至第5年有虫株率均保持在0.1%以下的低水平,天敌的寄生率仍高达92%,表明持续控制作用十分显著。研究中,还对我们计算出的回归模型y=-51.60795+77.47512lgx进行了实际检验。结果显示,利用该模型计算出的多种天敌的总寄生率与实际调查所得的总寄生率之间没有显著差异,因此,该模型可以用于调查天敌的寄生率,能够大大节约工作量,利于生产单位实际应用。

Releasing parasitoid Chouioia cunea Yang for biological control of the Fall Webworm Hyphantria cunea （Drury）, an serious invasive defoliator has been researched in China from 1998 to 2003. Results showed that the Fall Webworm population could be effectively put under control when releasing the parasitoid in the full-grown larval and early pupal stages of Fall Webworm respectively and in two consecutive generations, with release proportion of 5 wasps versus 1 host larva. The infested rates of trees reduced to 1.25 %, and total parasitism rates of Fall Webworm attacked by natural enemies reached 92.67 % after carrying out the biological control measures for the first year. Occurrence of 10 generations of Fall Webworm has been traced continuously for 5 years after release of C. cunea, it indicated that this chalcidoid parasitoid had excellent sustainable control effectiveness on Fall Webworm. The infested tree rates kept under 0.1% and parasitism rates of Fall Webworm by insect natural enemies were still beyond 92% from the 2nd to 5th year after applying the biocontrol measure, which demonstrated the significant sustainable control effects of C. cunea. In addition, a new regression model （ y = - 51.607 95 ＋ 77.475 12 lgx） we established on parasitism rates between total insect natural enemies and C. cunea itself has also been evaluated in practice. Results revealed that the total parasitism rates calculated by this model did not significantly differ with those from practical investigation. Thus, the model is usable in the survey of parasitism rates by operating organizations for greatly saving works.