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根据稻纵卷叶螟Cnaphalocrocis medinalis Guenee对水稻危害的特点,作者对不同虫量的危害程度与水稻产量损失的关系,进行了测定和分析。结果表明:危害平均严重度或危害指数与产量损失呈平衡动态关系,空壳率的上升是产量损失的直接原因,其防治费用与产量损失金额相等时的经济阈值为:X_1=(1/(0.243))ln((1.7102CN+C_1)/(4.9034CN)(卷叶率)一般田块,防治指标的虫口密度为百株3.19—4.92头二、三龄幼虫。
According to the characteristics of rice harms caused by Cnaphalocrocis medinalis Guenee and the relationship between the harm degree of different insect pests and the yield loss of rice, the author conducted the determination and analysis. The results showed that the average severity of hazard or hazard index was in a dynamic relationship with the yield loss. The increase of shell percentage was the direct cause of yield loss. The economic threshold when the cost of prevention and control was equal to the yield loss was: X 1 = (1 / 0.243)) ln ((1.7102CN + C_1) / (4.9034CN) (Volume leaf rate) General field, prevention and control index population density of one hundred 3.19-4.92 first and second instar larvae.