Residue and safety evaluation of diflubenzuron in litchi

ObjectiveSafety of diflubenzuron in litchi was evaluated, in order to provide a scientific basis for ratio-nal use of diflubenzuron in litchi production . MethodAn effective method was developed for quantitative analysis of diflubenzuron by HPLC-PDA(high performance liquid chromatography with photo-diode array) in whole fruit and flesh of litchi. Terminal residue and degradation dynamics of diflubenzuron in litchi were studied in Guangdong and Guangxi during 2013-2014. ResultResults showed that, spiked recoveries of diflubenzuron in whole fruit and flesh of litchi were 84.1%-84.8% and 82.7%-84.9%, respectively, with relative standard deviations of 2.9%-4.3% and 3.2%-4.2%. Limit of detection(LOD) was 5×10-10 g, and limit of quantification(LOQ) was 0.01 mg/kg in whole fruit and flesh. Half life of di-flubenzuron in litchi was 3.5-4.9 d. Furthermore, terminal residues of diflubenzuron in flesh were less than 0.01 mg/kg, terminal residues of diflubenzuron in whole litchi were 0.05-0.23 and 0.01-0.05 mg/kg, respectively, when spraying 125.0-187.5 mg/kg diflubenzuron three or four times, and pre-harvest interval was 7 or 10 days. ConclusionRecom-mended dosage of diflubenzuron is 125.0 mg/kg for prevention and control of Conopomorpha sinensis Bladley by spraying three times at pre-harvest interval of 10 days.