Systemic assessment of the chiral insecticide pyriproxyfen in a citrus nectar source system: Stereoselective degradation, biological effect and exposure risk. Issue 7 (11th May 2022)

• Record Type: Journal Article
• Authors: Tong, Zhou; Yang, Tingmi; Sun, Mingna; Dong, Xu; Chu, Yue; Meng, Dandan; Wang, Mei; Gao, Tongchun; Duan, Jinsheng
• Is Part Of: Pest management science. Volume 78:Issue 7(2022)
• Page Start: 3012
• Page End: 3018
• Publication Date: 2022-05-11
• Subjects: pyriproxyfen -- citrus nectar system -- enantioselective -- degradation -- bioassay and toxicity -- exposure risk; Pests -- Control -- Periodicals; Pesticides -- Periodicals; 632.9
• DOI: 10.1002/ps.6926
• Languages: English
• ISSNs: 1526-498X

Abstract

Abstract: BACKGROUND: Balancing the safety and efficiency of chiral pesticides can help protect pollinators. We evaluated the stereoselective behavior, bioactivity, toxicity and exposure risk of the chiral insecticide pyriproxyfen in a citrus nectar system. RESULTS: Density functional theory (DFT) and ultra‐performance liquid chromatography tandem mass spectroscopy (UPLC–MS/MS) were applied for absolute configuration appraisal and chiral analysis validation, respectively. The recoveries ranged from 72.3% to 100.5% with an relative standard deviation (RSD) ranging from 1.2% to 9.7%. In a field trial, we determined insecticide half‐lives in citrus leaves and flowers, which were 7.0 and 8.6 days for R ‐(+)‐pyriproxyfen, and 11.7 and 14.7 days for S ‐(−)‐pyriproxyfen, respectively. We found that the bioactivity of R ‐(+)‐pyriproxyfen was 3.39 and 2.37 times higher than S ‐(−)‐pyriproxyfen against Unaspis yanonensis and Diaphorina citri nymphs, respectively. S ‐(−)‐pyriproxyfen had 3.8 times higher acute toxicity than R ‐(+)‐pyriproxyfen on Apis mellifera L ., and its exposure risk was moderate based on the hazard quotient. CONCLUSION: The phenomenon of stereoselective degradation and biological effect demonstrated that the high‐risk stereoisomer of S ‐(−)‐pyriproxyfen degraded more slowly than R ‐(+)‐pyriproxyfen, but R ‐(+)‐pyriproxyfen with better efficiency for target. Therefore, an increased duration of R ‐(+)‐pyriproxyfen activity on citrus was beneficial for efficacy. Our results could guide the scientific application and evaluation of chiral pesticides on nectar plants. © 2022 Society of Chemical Industry. Abstract : Systemic assessment of the chiral insecticide pyriproxyfen in a citrus nectar source system. Absolute configurations and chiral analysis validation for pyriproxyfen (PYR). R ‐(+)‐PYR degraded faster than S ‐(−)‐PYR in a citrus system. R ‐(+)‐PYR was higher than S ‐(−)‐PYR against to U. yanonensis and D. citri nymphs. S ‐(−)‐PYR had higher toxicity and exposure risk to Apis mellifera L.