三种赤眼蜂对灰白蚕蛾的卵龄选择

Host age selection for eggs of Ocinara varians by three Trichogramma species

灰白蚕蛾Ocinara varians是近年来华南地区为害较严重的园林害虫,为筛选有效防治灰白蚕蛾的赤眼蜂种,在室内条件下比较了短管赤眼蜂Trichogramma pretiosum、松毛虫赤眼蜂T.dendroli-mi和暗黑赤眼蜂T.euproctidis对不同卵龄灰白蚕蛾卵的寄生能力和适应能力。结果显示,随寄主卵龄的增加松毛虫赤眼蜂和暗黑赤眼蜂寄生卵数均呈下降趋势,且都在灰白蚕蛾卵龄为6 h的卵上寄生卵数最多,分别为15.90粒/雌和12.20粒/雌;而短管赤眼蜂的寄生卵数随寄主卵龄的增加呈先上升后下降趋势,在卵龄为24h时达最高,为8.25粒/雌;在各卵龄段,松毛虫赤眼蜂的寄生卵数均比其它2种蜂多;当寄主卵龄超过72 h时,3种赤眼蜂的寄生卵数均显著下降。3种赤眼蜂在寄生卵龄为6 h的寄生卵上羽化率最高,当卵龄超过72 h时,其羽化率均显著下降。松毛虫赤眼蜂和暗黑赤眼蜂对6 h卵龄的灰白蚕蛾卵致死能力最强,而短管赤眼蜂对24 h卵龄的灰白蚕蛾卵致死能力最强。综合分析表明,松毛虫赤眼蜂在灰白蚕蛾卵上的寄生能力和适应能力最好,是灰白蚕蛾的有效天敌。

Ocinara varians Walker is one of the most serious insect pests of ornamental plants in southern China in recent years. In order to screen effective Trichogramma species against O. varians, the parasitic capacity and suitability of three egg parasitoids, Trichogramma pretiosum Riley, T. dendrolimi Matsumura and T. euproctidis （Girauh） , to different ages of O. varians eggs were compared in the laboratory. The results revealed that the number of eggs parasitized by T. dendrolimi and T. euproctidis decreased as the host egg age increased, and the two species reached their maximum parasitizing capability on 6 h-host egg with 15.9 and 12.2 eggs per female, respectively. However, the number of eggs parasitized by T. pretiosum increased firstly and then decreased, and its maximum parasitizing capability was observed on 24 h-host egg with 8.3 eggs per female. The parasitizing capability of T. dendrolimi was higher on all host egg ages than the other two species of Trichogramma. When the host egg age was over 72 h, the parasitizing capa- bilities of three species declined dramatically. The emergence rates of three Trichogramma species reached the highest on 6 h-parasitized eggs, and dramatically decreased when the age of parasitized eggs were over 72 h. T. dendrolimi and T. euproctidis had the strongest fatalities to 6 h-host eggs, while T. preti-osum had the strongest fatalities to 24 h-host eggs. In conclusion, T. dendrolimi showed the best parasitizing capability and suitability on O. varians eggs, indicating that it had the potential ability as an effective biological control agent for controlling O. varians.