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玉米螟是玉米主要害虫,自七十年代以来,对棉花的为害也不断加重,受害严重的,产量损失达二成以上。所以,了解和掌握玉米螟在棉田的发生规律,合理地使用农药,对夺取棉花丰收具有极为重要的意义。一、应用幼虫分龄法预测成虫发生期以往研究结果表明,幼虫分龄法是依据幼虫的虫龄结构来预测成虫的发生期,其准确性取决于虫源田的选择和查虫的时间。从玉米螟寄主转换来看,上海郊区第一代玉米螟为害春玉米及部分早栽棉花,第二代为害棉花茎杆和玉米雌穗。因此,预测第二代就得在春玉米田查虫,第一次在6月20日左
Corn borer is the main pest of corn. Since the 1970s, the damage to cotton has also been aggravated. The serious damage is caused by over 20% yield loss. Therefore, to understand and grasp the occurrence of corn borer in the cotton law, the rational use of pesticides, to seize the harvest of cotton is extremely important. First, the use of larvae age of adults predict the occurrence of past research results show that the larvae age method is based on larvae age structure prediction of the occurrence of adult worms, the accuracy depends on the choice of insect fields and check time. From the conversion of corn borer host point of view, the first generation of corn borer in Shanghai suburbs damaged spring corn and part of the early planting cotton, the second generation damage cotton stems and corn ears. Therefore, it is predicted that the second generation will have to search for insects in the spring corn field, the first time will be left on June 20