两种赤眼蜂在半自然条件下对灰白蚕蛾卵的搜索寄生能力

灰白蚕蛾Ocinara varians Walker是近几年来我国南方发生比较严重的园林害虫之一,赤眼蜂是其卵期的一种重要天敌,为寻找灰白蚕蛾有效的生物防治措施,本实验研究了半自然条件下松毛虫赤眼蜂Trichogramma dendrolimi Matsumura和短管赤眼蜂Trichogramma pretiosum Riley对灰白蚕蛾卵的搜索寄生能力。实验结果表明,在挂卵量相同的情况下,3种不同经历的松毛虫赤眼蜂和短管赤眼蜂对灰白蚕蛾卵的搜索能力都随蜂卵比的减小而降低。在各蜂卵比下,3种不同处理的松毛虫赤眼蜂对灰白蚕蛾卵的寄生率明显高于相应地3种不同处理的短管赤眼蜂。在蜂卵比为1∶1时,具有羽化后学习经历的松毛虫赤眼蜂对灰白蚕蛾卵的搜索能力最强,其寄生率达50.66%,显著高于幼期学习蜂和无经验蜂,而幼期学习经历对其搜索效果无明显地影响。短管赤眼蜂无论是羽化后学习经历还是幼期学习经历对其搜索行为均无明显影响。

The searching capacity of two Trichogrammas species for Ocinara vrians in semi-field

The gray silk moth,Ocinara varians Walker,is one of more serious pests in gardens in south China.Trichogramma spp.is an important egg parasitoid of this pest.In order to search for alternative control methods,the searching capacity of Trichogramma dendrolimi Matsumura and T.pretiosum Riley was tested by releasing adult parasites in cages（60 cm × 60 cm × 70 cm）.Each cage included two host plants and had the same host egg numbers.The results show that,irrespective of whether parasitoids had prior experience of parasitizing O.varians eggs,the search capacity of T.dendrolimi and T.pretiosum declined as the parasitoid to egg ratio decreased.The rate of parasitism of T.dendrolimi was higher than that of T.pretiosum irrespective of prior experience.At a ratio of one parasitoid to one egg,adult T.dendrolimi that had prior experience of parasitizing O.varians eggs parasitized 50.7% of eggs,significantly higher than the proportion parasitized by larvae of this species that either had,or did not have,prior experience.Prior experience had no effect on the search efficacy of T.dendrolimi larvae,nor did it affect the search efficiency of adult or larval T.pretiosum.