Residual pesticides in grape leaves (Vitis vinifera L.) on the Egyptian market and human health risk

Is Common Dandelion (Taraxacum officinale agg.) Foraged for Food in Vineyards Pesticide Residues Free?

Consumption of common dandelion (Taraxacum officinale agg.) can pose a risk when foraged in agroecosystems like vineyards where pesticides are frequently used. The aims of our study are to evaluate whether dandelion foraged in vineyards with different management practices (integrated pest management, organic, and biodynamic) in spring is suitable for consumption and to assess whether the contents of selected pesticide residues (PR) in integrated vineyards in dandelion vary throughout the seasons. Young dandelion leaves were sampled in spring, summer, and autumn in integrated vineyards, while in spring also in organic and biodynamic vineyards. The selected PR was analyzed using GC-MS/MS and LC-MS/MS, using extraction with acetonitrile. The method was validated on a dandelion matrix according to international guideline SANTE 11312/2021. Despite the use of many pesticides in integrated vineyards, only tebuconazole was detected in spring in one sample (0.005 mg/kg), while no PR was detected in dandelion from organic and biodynamic vineyards. However, at summer sampling seven different PR were detected, of which the kresoxim-methyl maximum residue limit was exceeded in five samples (0.012-0.029 mg/kg), while in autumn no PR was detected. Based on this study, it seems that dandelion leaves foraged in vineyards in spring could be unproblematic for consumption.

Decline pattern and dietary risk assessment of spinetoram in grapes under Egyptian field conditions

Spinetoram is one of the most extensively used insecticides globally and is a new spinosyn-based insecticide registered for direct treatment of Egyptian grapes. This work established and validated a developed method for determining spinetoram in grape berries and leaves using the QuEChERS coupled LC-MS/MS technique. The average recoveries ranged between 98.52-101.19% and 100.53-104.93%, with RSDs of 2.74-6.21% and 2.79-7.26% for grape berries and leaves, respectively. Spinetoram residues degraded in grape berries and leaves through a first-order kinetic, with an estimated half-life (t1/2) of 4.3 and 2.8 days in grape berries and leaves, respectively, and significant degradation (91.4-97.5%, respectively) after 14 days. Besides, the terminal residues of spinetoram detected in grape berries and leaves samples ranged between 0.017-0.077 mg‧kg-1 and 0.79-0.023 mg·kg-1, respectively, when applied two to three times at a single recommended rate, while it was varied between 0.026-0.44mg‧kg-1 and 0.79-0.023mg‧kg-1 when applied two to three times at a double recommended rate, respectively. A dietary risk assessment was conducted using scientific data from field trials, acceptable daily intake (ADI), and food consumption. It was determined that no noteworthy health hazards were connected to eating grape berries and leaves that had been treated with spinetoram since the risk quotients (RQs) were ≤ 0.4.

Influence of the agrochemical benomyl on Cryptococcus gattii-plant interaction in vitro and in vivo

Cryptococcus gattii, an environmental fungus, is one of the agents of cryptococcosis. The influence of agrochemicals on fungal resistance to antifungals is widely discussed. However, the effects of benomyl (BEN) on fungal interaction with different hosts is still to be understood. Here we studied the influence of adaptation to BEN in the interaction with a plant model, phagocytes and with Tenebrio molitor. First, the strain C. gattii L24/01 non-adapted (NA), adapted (A) to BEN, and adapted with further culture on drug-free media (10p) interact with Nicotiana benthamiana, with a peak in the yeast burden on the 7th day post-inoculation. C. gattii L24/01 A and 10p provided lower fungal burden, but these strains increased cell diameter and capsular thickness after the interaction, together with decreased fungal growth. The strains NA and A showed reduced ergosterol levels, while 10p exhibited increased activity of laccase and urease. L24/01 A recovered from N. benthamiana was less engulfed by murine macrophages, with lower production of reactive oxygen species. This phenotype was accompanied by increased ability of this strain to grow inside macrophages. Otherwise, L24/01 A showed reduced virulence in the T. molitor larvae model. Here, we demonstrate that the exposure to BEN, and interaction with plants interfere in the morphophysiology and virulence of the C. gattii.

Sulfoxaflor residues and exposure risk assessment in grape under Egyptian field conditions

Grapes are among the most popular fruits globally, and insecticides are commonly used on grape farms. Sulfoxaflor, a novel sulfoximine insecticide that works against various insect pests, is extensively used in Egypt. Our field trials assessed the dynamics and final residues of sulfoxaflor in grapes and grape leaves grown in Egyptian environments with different application rates, including worst-case scenarios. A QuEChERS-based method with LC-MS/MS was used to analyze residues of sulfoxaflor in grapes and grape leaves. The limit of quantification (LOQ) was validated at 0.01 mg‧kg-1. Sulfoxaflor residues are degraded in grapes and grape leaves according to a first-order kinetic model, with an estimated half-life (t1/2) of 7.04 and 7.7 days, respectively, and considerable degradation (74.68 and 72.16%, respectively) after 14 days. The final residues in grapes and grape leaves were below the Codex or EU maximum residue limit (MRL) (2 mg‧kg-1) after 3 days of the recommended and high application rates. The findings showed that grapes and leaves treated with sulfoxaflor at the recommended rate are safe for humans 3 days after two or three consecutive treatments with intervals of 14 days. The current study should pave the way for implementing safe and appropriate sulfoxaflor use in grapes and grape leaves in Egypt.

Determination, temporal variation and potential health risk assessment of pesticide residues in grapes from South and Southwest China

Pesticide residues in grapes from South and Southwest China were determined using the QuEChERS procedure and UHPLC-MS/MS and GC-MS/MS methods. The 4-year monitoring and survey showed 94.6% of the 1341 samples of grapes collected from eight main production areas contained one or multiple pesticide residues (above the respective LOQs). Overall, 40 pesticides were detected, including 24 fungicides, 12 insecticides, 2 acaricides and 2 plant growth modulators, of which one pesticide was unauthorised for use in treating grapes. Two or more pesticide residues were discovered in 87.4% of the samples (above the respective LOQs), and pesticide residues in 5.7% of the samples exceeded the MRLs, such as difenoconazole, cyhalothrin, propiconazole, etc. The main risk factors affecting the safety of grape before 2019 were difenoconazole, cyhalothrin and cyazofamid. After 2019, however, the frequency of occurrence of the above pesticides significantly declined, and the banned or restricted pesticides including omethoate were not found, which was credited to the stricter supervision and management policies by local governments. Despite the high detection rates and multi-residue occurrence of pesticides in grapes, about 84% of the samples were compliant with regulatory standards. Moreover, the accumulative chronic diet risk determined from ADI is very low. This study and timely monitoring can ensure that grape growers comply with GAP and minimise the occurrence of residues.

SERS combined with QuEChERS using NBC and Fe3O4 MNPs as cleanup agents to rapidly and reliably detect chlorpyrifos pesticide in citrus

The surface-enhanced Raman spectroscopy (SERS) technique is being increasingly used for the detection of pesticide residues in agricultural products. However, there are large amounts of fluorescence-producing substances in agricultural products, which seriously affect the Raman signal of the analyte. In this paper, the QuEChERS method was used to remove interfering fluorescent substances in the analyte, and the purification effects of different doses of nano bamboo charcoal (NBC) and Fe3O4 magnetic nanoparticle (Fe3O4 MNP) adsorbents were studied. Meanwhile, the Raman spectral acquisition conditions (AuNPs, test solution, and NaCl) were optimized based on the orthogonal test method. The results showed that 300 µL AuNPs, 40 µL test solution, and 100 µL 1.5% NaCl gave the best SERS response effect. 12.5 mg NBC combined with 10 mg Fe3O4 MNPs could effectively remove the interfering substances from citrus. The Raman spectra of chlorpyrifos molecules were theoretically modeled using density-functional theory (DFT). By comparing the DFT results with the actual tests, five feature peaks, at 338, 522, 558, 672, and 1600 cm-1, were obtained for the detection of chlorpyrifos pesticide residues in citrus. Based on the Raman feature peak intensity at 672 cm-1, the concentration of chlorpyrifos in citrus showed a good linear relationship (R2 = 0.9979) in the concentration range of 3-20 mg kg-1. The recovery rate was 92.12% to 98.38%, and the relative standard deviation (RSD) was 1.77% to 5.29%. The lowest detection concentration was about 3 mg kg-1, and the detection time of a single sample could be completed within 15 min. This study showed that the combination of SERS and QuEChERS preprocessing methods could achieve rapid detection of chlorpyrifos pesticide residues in citrus.

Dissipation kinetics of some pesticides applied singly or in mixtures in/on grape leaf

BACKGROUND

Grape and leaf quality are often severely reduced by fungi such as grey rot Botrytis cinerea Pers., powdery mildew Erysiphe necator Schwein, and downy mildew Plasmopara viticola (Berk. & M.A.Curtis) Berl. & De Toni and by insects such as Otiorhynchus spp., European grapevine moth Lobesia botrana Den.-Schiff., vine mealybug Planococcus citri Risso, and grape erineum mite Colomerus vitis Pgst. Various pesticides are often applied to mitigate these pest problems. These chemicals used singly as well as in the form of a mixture can leave residues on or in the crop. It is therefore of great importance to study the dissipation of the pesticides applied alone and in mixtures to this crop to protect consumers.

RESULTS

The dissipation kinetics of cypermethrin, boscalid, deltamethrin, kresoxim-methyl, lambda-cyhalothrin, metalaxyl-M, metrafenone, and triadimenol residues were studied in vine leaves grown under sunny conditions in Turkey. The dissipation rate for singly applied pesticides followed first-order kinetics, with half-lifes in grape leaves in the range of 1.85-7.22 days. Changes in the degradation process of pesticide residues were determined after application, as both single applications and mixtures. The degradation of boscalid, cymoxanil, deltamethrin and metalaxyl-M accelerated while the degradation of cypermethrin, kresoxim-methyl, and lambda-cyhalothrin slowed down in mixtures of pesticides.

CONCLUSION

The use of pesticides in mixtures leads to slower degradation and higher residues for some active ingredients and faster degradation and fewer residues for other active ingredients. Therefore, pesticide mixtures should not be applied in the field without having detailed information about their ingredients. © 2022 Society of Chemical Industry.

Effect of ultrasound assisted cleaning on pesticide removal and quality characteristics of Vitis vinifera leaves

In this study, the pesticide (acetamiprid, deltamethrin, and pyridaben) removal and physicochemical quality improvement of vine (Vitis vinifera) leaf were examined using ultrasonic and traditional cleaning for 5, 10, and 15 min. After an ultrasonic cleaning procedure at 37 kHz for 10 min, acetamiprid, deltamethrin, and pyridaben in vine leaf were reduced by 54.76, 58.22, and 54.55 %, respectively. Furthermore, the total phenolic content (TPC) in vine leaf increased to 13.45 mg GAE/g DW compared to that in control samples using traditional cleaning (10.37 mg GAE/g DW), but there were no significant differences in DPPH radical scavenging activity. After 15 min of conventional cleaning, the total chlorophyll and total carotenoid content of leaves were found to be lowest among all samples, at 6.52 mg/kg and 0.48 mg/kg, respectively. In conclusion, when compared to conventional cleaning methods, ultrasonic cleaning with no chemicals or heat treatment has proven to be a successful and environmentally friendly application in reducing commonly used pesticides and improving the physicochemical qualities of leaves.