Pymetrozine,4,5-dihydro-6-methyl-4-(3-methyl-amino pyridine)-1,2,4-3 (2H)-ketone, was a novel selective insecticide whose basic structure is a pyridine. It was discoveried and developed by Novartis in Swiss. Pymetrozine kill pests very quickly because of contact action and the absorption activity, so can be used for foliar spray and soil treatment. According to reports, Japan, EU and other developed countries has been developed maximum residue limits (MRL) of pymetrozine in rice, but China has not yet devel...