控制小菜蛾的赤眼蜂田间种群保护与增殖研究

通过建立十字花科蔬菜间作甜玉米、黑光灯诱虫育蜂笼这2种田间保护增殖措施，探讨了玉米螟赤眼蜂Trichogramma ostriniae、拟澳洲赤眼蜂T.confusum以及卷蛾分索赤眼蜂Trichogranunatoidea baarae对小菜蛾Plutella xylonella种群数量控制的作用．结果表明：十字花科蔬菜地间作甜玉米使得玉米螟赤眼蜂对小菜蛾卵寄生率有明显的提高，为4．62％～11．47％；黑光灯诱虫育蜂笼的设立对田间小菜蛾卵寄生蜂的种群数量起到了良好的增殖作用，自2002年4月初到6月底，诱集小菜蛾产卵127300粒，培育卷蛾分索赤眼蜂10万多头．在育蜂笼设立初期，笼内小菜蛾卵的寄生率为87．34％，距笼5m之外其寄生率急剧下降，其有效扩散范围不超过20m．2个月后的调查表明，赤眼蜂可逐步扩散到离育蜂笼30m处，各调查点之间寄生率的差距逐渐缩小，在距笼25m范围内，小菜蛾卵的寄生率维持在50％以上，有效地抑制了小菜蛾种群数量的增长．

Natural Protection and Augment of Trichogramma Population for Controlling Plutella xylostella

Egg parasitism rate of diamondback moth(DBM),Plutella xylostella(L.),by Trichogramma ostriniae Pang et Chen was greatly enhanced when cruciferous vegetables intercropped with sweet corn,Zea mays(L.).During April to June,2001,egg parasitoid collected from crucifers-corn field was predominately T.ostriniae,and its parasitism varied from 4.62% to 11.47%.While parasitoid species in crucifer fields was T.confusum Viggiani,the parasitism rate of which was no more than 4%.Trap cage of black light for naturally rearing wasp also played an important role in population augment of the Trichogrammatoidea bactrae.About 100 000 Trichogramma wasps had been reared from 127 300 eggs laid by trapped DBM during April to June,2001.In the first month after the cage was set up,the parasitism rate within the cage was 87.34%.In the field the parasitism rate decreased with the increase of distance from the cage,the effective dispersion distance was no more than 20 m.However,the dispersion distance of wasps increased with the time.By the end of May 2001,two months after the trap cage was set up,Trichogramma wasps could arrive at the 30 m from the cage and the parasitism rate kept above 50% within 25 m around the cage.