转Bt基因玉米对棉铃虫的抗性评价

Evaluation of transgenic Bt maize for resistance to cotton ballworm

棉铃虫Helicoverpaarmigera(H櫣bner)是常年危害玉米的重要害虫。转Bt基因抗虫玉米为害虫的防治提供了新的途径。采用室内离体生物测定方法测定了孟山都转Bt基因抗虫玉米Yield-Gard(不同组织对棉铃虫初孵幼虫的杀虫活性以及田间人工接虫抗性鉴定。Bt玉米花丝、苞叶和幼嫩雌穗对棉铃虫具有较高的杀虫活性,取食Bt玉米花丝和幼嫩雌穗(籽粒和穗轴)的棉铃虫初孵幼虫不能存活和完成幼虫期发育,而对照分别有51.0%和22.0%个体完成幼虫期发育。以Bt玉米雌穗苞叶饲养棉铃虫初孵幼虫,5天后幼虫全部死亡,而非Bt玉米对照仅为16.0%,差异显著。田间花丝期人工接种棉铃虫抗性鉴定试验结果表明,Bt玉米雌穗被害率为3.5%,危害级别为0.007,百株存活幼虫14.3头。而非Bt玉米雌穗被害率达到82.5%,危害级别为2.51,平均百株存活幼虫79.6头,显著高于Bt玉米。这些结果说明转Bt基因玉米穗期对棉铃虫的防治效果明显。

Cotton ballworm, armigera （Httbner）, is an important insect pest of maize. The developments of transgenic Bt maize provide a new tool for corn borers control. Monsanto＇s YieldGard Bt transgenic maize expressing Cryl Ab protein and a non-Bt control were evaluated through laboratory bioassays by exposing neonates directly to silks, husk cover, young kennels and cobs that are the tissues initially attacked by neonates in the field. Field trials were also conducted with artificial infestations cotton ballworm at silk stages, respectively. Neonate of cotton ballworm fed on the silk, young kennels and cobs, and husk cover could lead to 53.0% , 90.0% and 100% mortality within 5 days respectively and all could not survive longer than 23 days. These were significantly difference compared with only 14.0%, 46.0%, and 16.0% mortality within 5 days and 51.0% （on silk） and 22.0% （young kennels and cobs） of larvae were pupaed finally for the negative control. There were only 3.5% ears with 0. 007 rating scale of damage and 14.3 larvae survived per hundred plants after artificial infestation at silk stage in field trial. These were significantly less than that of negative control that performed 82.5% ears with 2.51 rating scale of damage and 79.6 larvae survived per hundred plants. These results indicated that YieldGard provided good controls of cotton baUworm in reproductive stage.