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在湖北省荆州地区选择有代表性的中产棉田两块 ,进行了棉铃虫不同代别防治指标的研究。初步明确棉铃虫第三代危害期间 ,棉株有较强的补偿能力。百株低龄幼虫在 5头以内时有增产的趋势 ;5～ 1 5头之间蕾花铃总数保持相对稳定状态 ;当百株虫量大于 1 5头时 ,则蕾、花、铃迅速下降。第四代发生危害期间 ,棉株补偿能力已衰退或消失 ,当百株幼虫量达到 5头时 ,则蕾、花、铃总数迅速下降。因此第三代棉铃虫的防治指标为百株低龄幼虫 1 2头 ,每四代为百株低龄幼虫 5头。
Two representative middle-yielding cotton fields were selected in Jingzhou, Hubei Province, and the control indexes of different generations of cotton bollworm were studied. During the initial identification of the third generation of cotton bollworm, cotton plants have strong compensatory power. One hundred young larvae tended to increase their production when they were less than 5, while the total number of 5 ~ 15 buds remained relatively stable. When the number of pests was more than 15, the buds, flowers and bolls decreased rapidly. During the fourth generation, the compensation ability of cotton plants has declined or disappeared. When the number of 100 larvae reached five, the total number of buds, flowers and bells decreased rapidly. Therefore, the third generation of cotton bollworm prevention and control indicators for one hundred low-level larvae of 12, every four generations of one hundred young larvae.