早稻田笼罩接虫试验结果表明，白背飞虱不同虫量繁殖一个世代后，平均增殖２６．５７±５．２７倍，子代数量随着接虫数的增加而增加，子代短翅型成虫比例则相反；水稻受害后的秕谷率、千粒重、产量与虫量的关系符合用Ｌｏｇｉｓｔｉｃ曲线拟合的方程。同时提出了不同产量水平下的经济允许损失率和防治指标。 The results showed that the average population of whitebacked planthopper (Sophorus ruthenica L) was 26.57 ± 5.27 times more than that of the other one, and the number of progeny increased with the number of picked insects. The proportion was the opposite. The relationship between the rate of grain yield, grain weight, grain yield and the amount of insects after rice injury accorded with the equation fitted by Logistic curve. At the same time, it puts forward the economic allowable loss rate and prevention and control index under different production levels.