为减少苕溪流域农药施用量，降低该流域农药对水生生物的环境风险，通过调查苕溪流域防治卷叶螟虫（ Cnaphalocrocis medinalis）、稻飞虱（ Delphacidae）和水稻纹枯病的农药品种及用量，以农药暴露模拟外壳为工具，运用农药风险评价技术分析其产生的环境风险，并根据风险选择农药品种及用量。结果表明：以吡蚜酮代替噻嗪酮可减少农药用量765 g·hm－2，以阿维菌素代替骄子可减少农药0�75 L·hm－2，以爱苗替代井冈霉素可减少农药4�27 L·hm－2，替代后常规农药总用量降低5�79 L·hm－2。同时该替代技术对试验区水稻产量和病虫害的防治效果大多优于当地农户单独分散用药。由于控制了用药次数和用药量，用药成本下降，水稻种植的经济效益则增加。该技术在减少农药总施用量的同时也降低了农药对水生生物环境毒性的影响，从源头控制了农业面源污染中的化学污染物。%In order to reduce pesticide use in the Tiaoxi Watershed and lower environmental risk of the pesticides on a⁃quatic organisms, a field survey was carried out of types and rates of the pesticides used to control leaf borers, planthop⁃pers and rice sheath blight in the watershed;environmental risks of the pesticides assessed using the technique for pesti⁃cide risk assessment, and simulated shells for exposure of pesticides; and optimal types and optimal application rates of pesticides determined according to their risks, separately. Results show that the use of pymetrozine to replace buprofezin reduced the application rate of pesticide by 765 g·hm-2;the use of avermectin to replace Jiaozi did by 0�75 L·hm-2;and the use of Armure to replace Jinggangmycin did by 4�27 L·hm-2 . In total, the replacements of the conventional pesti⁃cides reduced the use of pesticides by 5�79 L·hm-2 . Meanwhile, the replacements improved crop yield and pest control effect in the experiment field over their respective ones in paddy fields of local farmers using conventional pesticide. Thanks to its lowered frequency and rates, the use of the replacement pesticides lowered pest control cost and in turn raised eco⁃nomic profit of the crop. Therefore, it could be concluded that this technology can reduce not only the total amount of pesti⁃cides to be used, but also their toxic impacts on aquatic bio⁃environment, thus controlling the non⁃point source chemical pollution at the source.
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