本文根据三化螟虫量与产量损失关系的测定、天敌因素的作用、化学防治的经济和生态效益、防治费用及稻谷市场价格变动情况等因素,制定出不同产量水平条件下的三化螟经济允许损失水平。并制定出产量水平在每公顷6000公斤的条件下,三化螟的经济阈值:早稻孕穗末期、始穗期和抽穗期分别为每公顷1260,1470和1710块卵块;晚稻分蘗期、孕穗末期、始穗期和抽穗期分别为每公顷1335、1380、1620和1890块卵块。 Based on the determination of the relationship between the number of stem borers and the loss of yield, the role of natural enemies, the economic and ecological benefits of chemical control, the cost of prevention and control, and the changes in the market price of rice, the economic feasibility of using the rice stem borer Loss level. The economic threshold of the stem borer was 1260, 1470 and 1710 eggs per hectare at the late booting stage, the tillering stage at the late rice stage, the end of the booting stage, 1335, 1380, 1620 and 1890 egg masses per hectare for the beginning and heading stages, respectively.