SYP-14288 is a fungicide as an uncoupler of oxidative phosphorylation, which is effective in controlling fungal pathogens like Rhizoctonia solani. To determine whether R. solani can develop SYP-14288 resistance and possibly multi-drug resistance (MDR), an SYP-14288-resistant mutant of R. solani X19-7 was generated from wild-type strain X19, and the mechanism of resistance was studied through metabolic and genetic assays. From metabolites of R. solani treated with SYP-14288, three compounds including M1, M2, and M3 were identified according to UPLC-MS/MS analysis, and M1 accumulated faster than M2 and M3 in X19-7. When X19-7 was treated by glutathione-S-transferase (GST) inhibitor diethyl maleate (DEM) and SYP-14288 together, or by DEM plus one of tested fungicides that have different modes of action, a synergistic activity of resistance occurred, implying that GSTs promoted metabolic resistance against SYP-14288 and therefore led to MDR. By comparing RNA sequences between X19-7 and X19, six cytochrome P450s (P450s) and two GST genes were selected as a target, which showed a higher expression in X19-7 than X19 both before and after the exposure to SYP-14288. Furthermore, heterologous expression of P450 and GST genes in yeast was conducted to confirm genes involved in metabolic resistance. In results, the P450 gene AG1IA_05136 and GST gene AG1IA_07383 were related to fungal resistance to multiple fungicides including SYP-14288, fluazinam, chlorothalonil, and difenoconazole. It was the first report that metabolic resistance of R. solani to uncouplers was associated with P450 and GST genes.

/pdf/cytochrome-p450-and-glutathione-s-transferase-confer-3p7tb1uc.pdf

Cytochrome P450 and Glutathione S-Transferase Confer Metabolic Resistance to SYP-14288 and Multi-Drug Resistance in Rhizoctonia solani

The aim of this survey was to evaluate the residue levels, distribution and exposure risk of the 38 most commonly used pesticides in rapeseed samples collected from the main production areas in China over a two-year period. The sampling area covered 12 provinces, including Guizhou, Shaanxi, Yunnan, Hunan, Jiangxi, Sichuan, Chongqing, Anhui, Henan, Hubei, Zhejiang, and Jiangsu provinces. The pesticide residues were determined using a QuEChERS (Quick Easy Cheap Effective Rugged and Safe) method coupled with gas chromatography-tandem mass spectrometry and liquid chromatography-tandem mass spectrometry. 8.4% of the rapeseed samples contained pesticides with a residue level ranging from 0.001 to 0.634 mg/kg. The detected analytes were imidacloprid, quizalofop-P-ethyl, thiamethoxam, paclobutrazol, prochloraz, tebuconazole, difenoconazole, s-metolachlor, carbofuran, and carbendazim. The concentrations of four analytes, including thiamethoxam, difenoconazole, carbendazim and prochloraz, exceeded the maximum residue level set by the Chinese government for rapeseed, with exceedance rates of 0.1%, 0.1%, 0.1%, and 1.1%, respectively. Based on the index of quality for residues (IqR) values, 91.6% of the total rapeseed samples had an IqR category of Excellent (IqR = 0). Only 1.5% of the tested samples were of inadequate quality. Furthermore, the assessment of chronic and acute exposure, as well as health risks associated with pesticide residues in rapeseed, was conducted for different age groups within the Chinese population, including adults (6-14 years), children (15-49 years), and the elderly (50-74 years). The results of this assessment indicated that pesticide residues in rapeseed cultivated in China are not expected to be of short- or long-term risks to the Chinese customers. 

A study of the pesticide residues in rapeseeds in China: Levels, distribution and health risk assessment.

The frequent and massive use of pesticides has led to pesticide residues in apricot, threatening food safety and human health. A reliable and simple modified QuEChERS method with ultra-performance liquid chromatography-tandem mass spectrometry was developed for the simultaneous determination of 11 pesticides in apricot. Method validation indicated that satisfied linearity (R2 ≥ 0.9959), accuracy (recoveries of 72-119%), sensitivity (limits of detection, 0.03-0.30 μg/kg; limits of quantification, 0.13-1.00 μg/kg), and precision (relative standard deviations ≤ 11.9%), and matrix effects were 0.89-1.13. Apricot samples from different ecological regions in China were collected and tested using the proposed methods. Monitoring results were used to assess the dietary intake risk of Chinese populations of different ages and genders. Dietary risk assessment revealed that the risk quotients were 0.003-1.184% for different gender and age groups in China, indicating none unacceptable public health risk for general population. This work was thus significant in developing a simpler, more efficient and economical analysis method and food safety risks of the 11 pesticides on apricot and facilitated the establishment of maximum residue limits. 

/pdf/residual-levels-and-dietary-intake-risk-assessment-of-11-7dv20m89.pdf

Residual levels and dietary intake risk assessment of 11 pesticides in apricots from different ecological planting regions in China

Abstract In this study, fluopyram (FOR), acetamiprid (ATP) and chlorantraniliprole (CAP) were used individually or in combination at the maximum recommended dose in greenhouse strawberries to research the dissipation dynamics and dietary risks. A multi-residue analytical method for FOR, ATP and CAP in strawberries using UPLC-MS/MS integrated with QuEChERS approach was develop with a strong linearity (R 2 ≧ 0.9990), accuracy (recoveries of 82.62–107.79%), and precision (relative standard deviations of 0.58–12.73%). The limits of quantification were 0.01 mg kg − 1 . Field results showed that the half-lives of FOR, ATP and CAP in strawberry fruits were 11.6–12.4 days, 6.1–6.7 days and 10.9–11.7 days, respectively. The half-lives of the three investigated pesticides showed no significant difference when used individually or in combination. A risk assessment indicated that the dietary intake risks of the three pesticides in grown strawberries were 0.0041–7.63% whether applied alone or joint, which demonstrated that the dietary intake risks of three pesticides in grown strawberries could be negligible for Chinese male and female consumers, and even though pesticides were used in combination, there was no need to be concerned about the safety. This paper serves as a guide for the safe use of FOR, ATP and CAP on greenhouse strawberries. 

Residual behavior and risk assessment of fluopyram, acetamiprid and chlorantraniliprole used individually or in combination on strawberry

Hymexazol (HYM) is an active ingredient commonly used in a wide variety of crops; however, to date, there are no publications on its dissipation and residuality in strawberry fruits and leaves. The objective of the research was to evaluate the dissipation and residuality of hymexazol in strawberry using a modified QuEChERS method with UHPLC-ESI/MS-MS. For this, several validation experiments using the chromatographic method were conducted. The strawberry crop was established in the field, and the content of the HYM was monitored through several applications. The method showed good linearity (correlation coefficients > 0.9995), accuracy (recoveries in 73.7–109.4%), and sensitivity (limits of quantification 0.017 mg kg−1). Despite the two and four drench-treatments of HYM in the strawberry crop, the compound was not detected at levels above the LOD 24 and 48 h after the last treatment. This is due to various plants metabolizing hymexazol to glucose conjugates of its tautomers, i.e., its O-glucoside and N-glucoside, probably with low or null movement to the aerial parts and fruits of the crop.

/pdf/assessment-of-residuality-of-hymexazol-in-strawberry-2rtkfmvr.pdf

Assessment of Residuality of Hymexazol in Strawberry (Fragaria × ananassa) Crop by a Modified QuEChERS Method and Liquid Chromatography Tandem-Mass Spectrometry

A method based on QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation coupled with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for determining 43 pesticide residues in strawberries. The clean-up sorbents were optimized, with 50 mg PSA + 50 mg C18 + 150 mg MgSO4 showing the best performance in d-SPE. The effect of injection volume on matrix effect (ME) was investigated. The proposed method had a linear range of 0.001–0.1 mg kg−1, and determination coefficients (R2) were greater than 0.995. Recoveries of the selected pesticides were 70.1–119.6% with relative standard deviations (RSD) at three concentrations (0.01, 0.05, and 0.1 mg kg−1) lower than 20%. The limit of quantification (LOQ) of the 43 pesticides was ≤ 0.005 mg kg−1. This method was applied to 80 strawberry samples collected from 8 villages in Beijing suburbs, and 12 pesticide residues were quantitatively detected with the concentrations ranging from 0.02 to 2.5 mg kg−1.

Determination of Pesticide Residues in Strawberries by Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry

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Determination of Pesticide Residues in Strawberries by Ultra-performance Liquid Chromatography-Tandem Mass Spectrometry