The frequent and massive use of chlorfenapyr has led to pesticide residues in crops, threatening food safety and human health. However, there is limited research on the detection of tralopyril, which is the major metabolite of chlorfenapyr with high toxicity. This study aimed to develop a novel, sensitive, and highly efficient method for the determination of chlorfenapyr and tralopyril residues in 16 crops. The optimized purification procedure provided satisfactory recovery of 76.6–110%, with relative standard deviations of 1.3–11.1%. The quantification values of pesticides in crop matrixes were all 0.01 μg kg−1. The optimal method was adopted to determine the chlorfenapyr and tralopyril residues in field trials in 12 regions in China and monitor their residues in 16 agricultural products. The results of the dissipation and terminal residue experiments show that the final residue of chlorfenapyr was less than MRL (maximum residue limit) and no tralopyril was detected in the field samples. Moreover, the qualification proportion of these residues in market samples were up to 99.5%. The RQ (risk quotient) values of chlorfenapyr and chlorfenapyr with consideration of tralopyril were both apparently lower than an RQ of 100%, indicating an acceptable level. This research provides a thorough long-term dietary risk evaluation on chlorfenapyr and tralopyril and would provide reference for their scientific and safe utilization.

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Salicylic acid (SA) is an important signal molecule, regulating oxidative stress response in plants. In this study, we evaluated the influences of SA (1mg L-1, 10mg L-1 and 50mg L-1) on the accumulation of clothianidin (CLO), dinotefuran (DFN) and difenoconazole (DFZ) (5mg L-1) and pesticide-induced (CLO-10mg L-1, DFN-20 mg L-1, and DFZ-10mg L-1) oxidative stress in cucumber plants. Exogenous SA at 10mg L-1 significantly reduced the half-lives of three pesticides in nutrient solution and prevented the accumulation of pesticides in roots and leaves. And the role of SA in reducing residues was related to the major accumulation sites of pesticides. By calculating the root concentration factor (RCF) and translocation factor (TF), we found that SA at 10mg L-1 reduced the ability of roots to absorb pesticides and enhanced the translocation ability from roots to leaves. Roots exposed to high concentrations of three pesticides could reduce biomass, low chlorophyll content, promote lipid peroxidation, and alter the activities of a range of antioxidant enzymes, respectively. Exogenous SA at low concentrations significantly mitigated these negative effects. Hence, we speculated that application of exogenous SA at 10 mg L-1 could effectively alleviate the accumulation of pesticides and induce stress tolerance in cucumber planting systems.