[Objective] The study aimed to understand the residual dynamics of pymetrozine in rice and its final residual amount in rice in the harvest. [ Method ] Field trial and high performance liquid chromatography were carried out to study the degradation dynamics of 25% py metrozine WP in rice plant and its final residue amount in rice in the harvest. [ Result] The degradation half-life of pymetrozine were 0.51 0. 53 d in the rice plant, which accorded with the dynamic equation of first-order chemical reactions. When the rice was sprayed one time with 25% pymetrozine WP in the growth stage according to the recommended dosage of 300 g/hm2 and high dosage of 600 g/hm2, the final residues of pymetrozine in rice straw, rice shells and rice were all below the limit of quantification at harvest time. [ Conclusion ] The pymetrozine is a easily degradable pesticide (half-life <30 d). When the rice was applied with 25% pymetrozine WP, the recommended dosage of 300 g/hm2 was suggested to apply in the rice one time. The MRL of pymetrozine in rice may be suggested to be 0.02 mg/kg temporarily.%[目的]了解吡蚜酮在水稻植株中的残留动态以及在收获期水稻中的最终残留量.[方法]通过田间试验和高效液相色谱分析技术,研究了25％吡蚜酮可湿性粉剂在水稻植株中的消解动态以及在收获期水稻中的最终残留量.[结果]吡蚜酮在水稻植株中的降解半衰期为0.51 ～0.53 d,符合一级化学反应动力学方程.在水稻生长期喷施1次,按推荐剂量300 g/hm2和2倍剂量600 g/hm2施用25％吡蚜酮可湿性粉剂,在收获期植株、糙米和稻壳中均未检出.[结论]吡蚜酮属于易降解农药(T1/2＜30 d).在水稻田使用25％吡蚜酮可湿性粉剂时,按推荐剂量300 g/hm2施药1次,建议水稻上最大残留限量值暂定为0.02 mg/kg.
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