Abstract: Objective: Field trials were conducted in 13 citrus production regions including Hunan and Hubei provinces to evaluate the safety of the application of acetamiprid and pyriproxyfen on citrus. The residue, dissipation dynamics and dietary risk assessment of acetamiprid and pyriproxyfen in citrus fruit were investigated. Methods: The samples were extracted with 1% acetic acid in acetonitrile, purified using a mixture of primary secondary amine and graphitized carbon black, and detected by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Results: Excellent linearity (R2 > 0.99) was observed between the response peak area and the concentration of acetamiprid and pyriproxyfen in the range of 0.001–0.5 mg/L. In whole citrus fruit and flesh spiked at 0.01, 0.5 and 2.5 mg/kg, the recoveries of acetamiprid and pyriproxyfen ranged from 83.0% to 104.3% and from 74.8% to 98.7% with relative standard deviation (RSDs) of 3.8% to 10.0% and 2.0 to 6.0%, respectively. The limits of quantification (LOQs) for the analytes were both 0.01 mg/kg. The dissipation dynamics of acetamiprid and pyriproxyfen in whole citrus fruit was fitted to a first-order kinetics model. The degradation half-lives of acetamiprid and pyriproxyfen in whole citrus fruit were 5.1–15.8 days and 4.5–21.2 days, respectively. Twenty-seven percent acetamiprid-pyriproxyfen dispersible concentrate was sprayed twice on citrus at the recommended dosage of 500 g/hm2 (2 000 × dilution). At a 7-day safety interval, the residues of acetamiprid and pyriproxyfen in citrus fruit ranged from less than 0.01 mg/kg to 0.45 mg/kg and to 0.68 mg/kg, respectively. At a 10-day safety interval, the residues of acetamiprid and pyriproxyfen in citrus fruit ranged from less than 0.01 mg/kg to 0.40 mg/kg and to 0.56 mg/kg, respectively and were both lower than the maximum residue limits (MRLs) for acetamiprid (0.5 mg/kg) and pyriproxyfen (2.0 mg/kg) according to the Chinese national standard. The risk assessment results showed that the acute and chronic dietary exposure risk of acetamiprid and pyriproxyfen ranged from 0.0% to 53.0% (much lower than 100%) for people in different age groups, which was at an acceptable level. Conclusion: This study can provide guidance for the safety evaluation and rational application of acetamiprid and pyriproxyfen in citrus.

Key words: citrus; acetamiprid; pyriproxyfen; residue; dietary risk assessment