松褐天牛肿腿蜂对松褐天牛低龄幼虫控制作用的研究

研究测定了松褐天牛肿腿蜂对松褐天牛1～3龄幼虫的控制作用,采用林间和室内罩网相结合的方法研究了2组松褐天牛肿腿蜂对松褐天牛幼虫的寄生情况.结果显示:在室内试验条件下,松褐天牛肿腿蜂产卵之前的刺蛰、补充营养取食能直接造成松褐天牛1～3龄幼虫死亡,对1、2及3龄幼虫的平均致死率分别为95.66％、85.91％、57.88％,并可产卵寄生2、3龄幼虫;林间释放2组松褐天牛肿腿蜂后,在刺蛰和补充营养取食后能有效寄生寄主的肿腿蜂雌蜂数量比例变化较大,有效肿腿蜂率最高为14.9％,最低为2.3％.松褐天牛肿腿蜂寄生行为不受寄主聚集程度的影响,但刚羽化出茧肿腿蜂雌蜂的寄生效率比经饲喂后的雌蜂高近5倍.从肿腿蜂单一个体来看,每头雌蜂补充营养取食和产卵寄生致死的松褐天牛幼虫数为2.1～7.7头.松褐天牛肿腿蜂雌蜂的补充营养习性及刺蛰、取食致死寄主行为在防治中有很重要的作用,表明该种肿腿蜂是防治松褐天牛的重要天敌,在生物防治松褐天牛幼龄幼虫上具有良好的应用前景.

Predation and Parasitism of Sclerodermus sp. (Hymenoptera: Bethylidae) on the Young Larvae of Monochamus alternatus (Coleoptera: Cerambycidae)

Sclerodermus sp. (Hymenoptera: Bethylidae) is one of the few known natural enemies of pine sawyer, Monochamus alternatus (Coleoptera: Cerambycidae). An experiment was carried out on controlling the larva of M. alternatus by using a parasitoid, Sclerodermus sp. The results are as follows. Laboratory experiment indicated that the parasitoid could kill 95.66% of the 1st instar larvae, 85.91% of the 2nd instar larvae, and 57.88% of the 3rd instar larva of pine sawyer by stinging and host-feeding (by predation). In addition, the bethylid could parasitize its host and complete a generation on the 2nd-3rd instar of its host larvae (by parasitism); the response of this parasitoid to its host, in field and indoor mesh, showed to be highly variable and unpredictable and between 2.3% and 14.9% of all parasitoids released and entered a target pine sawyer-infested cutlog. The parasitoid did not respond differently to aggregations of 1, 3, or 6 pine sawyer-infested cutlogs. However, the efficiency of Sclerodermus sp. released as carrying immature eggs of parasitized hosts was up to approximately five times higher than that when the parasitoid was released as carrying mature eggs. An individual parasitoid killed 2.1 to 7.7 pine sawyer larva by a combination of predation and parasitism on the average. The host-feeding characteristics of Sclerodermus sp. offer an important impact in the biological control for the use of this parasitoid.