转基因抗虫棉田释放赤眼蜂增强生物控害功能的研究

为了增强转基因抗虫棉与自然天敌的联合控害功能,为转基因棉田害虫控制策略的调整和制定提供依据,于2002年在山东省惠民县转基因抗虫棉田设置化防田和以释放赤眼蜂为主的综防田,研究了棉铃虫卵的分布格局、释放赤眼蜂对棉铃虫的控制效果及生态效应。结果发现:棉铃虫卵在棉株不同部位的分布差异较大,2代棉铃虫卵主要分布在叶正面、叶背面和茎尖,3代棉铃虫卵主要分布于蕾铃;在放蜂田,赤眼蜂对棉株不同部位棉铃虫卵的寄生率差异较大,2,3代棉铃虫时期对叶正面、叶背面、茎尖、蕾铃的棉铃虫卵寄生率均较高,对叶柄和茎杆处卵的寄生率较低;并以3代棉铃虫时期的寄生率较高;在2,3代棉铃虫时期分别连续释放3次赤眼蜂,对棉铃虫具有很强控制作用,2,3代棉铃虫卵的被寄生率分别为66.0%～70.7%和76.0%～81.2%,均显著高于化防田的自然寄生率(2代:7.0%～12.3%,3代:5.2%～7.4%);蕾铃被害率分别为2.2%和3.1%,均显著低于化防田(2代:8.5%,3代:20.9%);2代棉铃虫时期,放蜂田和化防田的棉铃虫卵量和幼虫数量差异均不显著,但3代棉铃虫以后,放蜂田棉铃虫卵量和幼虫数量均显著低于化防田,且放蜂田的捕食性天敌数量显著高于化防田。可见,转基因抗虫棉田棉花生长中后期通过释放赤眼蜂可有效防治棉铃虫,降低其为害,并有利于棉田捕食性天敌的保护。

Enhanced Pest Control Efficacy in Transgenic Insect-resistant Cotton Field by Mass-release of Trichogramma chilonis

To improve the integrated pest control efficacy of transgenic insect-resistant cotton and natural enemies,biological control efficacy and ecological effects of mass-releasing Trichogramma chilonis in transgenic insectresistant cotton(cv.Lumianyan15) field were surveyed in Huimin county,Shandong province in 2002,with the chemically controlled cotton field as control.Trichogramma showed high control efficacy on cotton bollworm eggs after three times of release both in the second and in the third generation bollworm periods.The parasitism on the second and third generation bollworm eggs were 66.0%-70.7% and 76.0%-81.2%,respectively,which were significantly higher than that in the control(second generation:7.0%-12.3%,third generation:5.2%-7.4%).And the injury rate of cotton buds and bolls in the second and third generation bollworm were 2.2% and 3.1%,respectively,which were significantly lower than that in the control(second generation:8.5%,third generation:20.9%).In the second generation bollworm period,number of bollworm eggs or larvae in the Trichogramma released cotton field did not differ to that in the chemically controlled field.But in the third generation,there were significantly less bollworm eggs and larvae in the Trichogramma released cotton field.There were more predators in the Trichogramma released cotton field.These results indicated that cotton bollworm in the transgenic insect-resistant cotton field can be effectively controlled by mass-releasing of T.chilonis.And the biocontrol method is also beneficial to predator protection in the cotton fields.