Thiamethoxam Residues Research Articles

Development of colloidal carbon-based immunoassay for the determination of thiamethoxam in medicinal and edible Lonicerae Japonicae Flos.

Thiamethoxam is one of the top three neonicotinoids found in the environment and in food. The widespread use of thiamethoxam in medicinal and edible herbs threatens their safe use. Therefore, it is particularly important to develop a rapid and simple approach to detect thiamethoxam residues in herbal medicines. In this study, colloidal carbon-based immunochromatographic strip (CNP-ICS) and colloidal gold-based immunochromatographic test strip (GNP-ICS) methods were respectively developed for the determination of thiamethoxam. The cutoff value of CNP-ICS was 0.1ngmL-1, which is six times more sensitive than that of the GNP-ICS method (0.6ngmL-1). The CNP-ICS method was applied to detect thiamethoxam in medicinal and edible Lonicerae Japonicae Flos (LJF) for the first time, with a limit of detection of 10ngg-1. The detection results of thiamethoxam in 26 batches of LJF samples by the CNP-ICS were consistent with those of the LC-MS/MS method. High residue levels (10.16-530.40ngg-1) and high detection rates (69.23%) of thiamethoxam in LJF were observed. The CNP-ICS prepared in this study has the merits of low cost, simple preparation, non-toxicity, and high sensitivity, which can be utilized for rapid field screening of thiamethoxam residues in complex matrices such as herbal medicines.

Dissipation kinetics and decontamination of chlorantraniliprole and thiamethoxam residues in curry leaves

ABSTRACT Herein, using liquid chromatography – tandem mass spectrometry, we validated a modified QuEChERS method to analyse thiamethoxam and chlorantraniliprole residues in curry leaves. These insecticides are part of a pest management module against the major curry leaf insect pests, psyllid and leaf roller. Based on the SANTE guideline, the method exhibited satisfactory recovery and precision. For both insecticides, the R2 value was 0.99. Furthermore, the determined limit of detection and limit of quantification were 0.008 and 0.025 mg/kg, respectively. The field persistence of both insecticides was longer, and below quantification limit was achieved within 30 and 40 days for chlorantraniliprole and 35 and 40 days for thiamethoxam. Residue degradation followed first-order kinetics, with longer half-lives of 5.08 and 5.28 days for chlorantraniliprole and 3.50 and 3.96 days for thiamethoxam at single (x) and double (2×) doses, respectively. For both insecticides, the hazard index (HI), calculated based on the highest residue on the day of insecticide treatment in the field study, was less than 1 at x and 2× doses, indicating an acceptable level of risk. Seasoning or quick frying of curry leaves in oil reduced maximum of thiamethoxam and chlorantraniliprole residues followed by treatment with NaCl (2%)/tamarind water (2%)/lemon water (2%) solutions. Analysis of 85 farm-gate samples revealed detectable residues of thiamethoxam in 25 samples (0.03–0.49 mg kg−1) and chlorantraniliprole in 1 sample (0.18 mg kg−1). The HI for the maximum quantity of insecticide residues detected in monitoring study was <1. Therefore, the research backs the idea of ensuring safe harvested produce, considering the field persistence of chlorantraniliprole and thiamethoxam in curry leaf and simple decontamination methods to satisfy consumer need for clean food commodity, if properly adopted.

First Detection of Thiamethoxam in a Free-Ranging Insectivorous Bird After its Agricultural Use Ban in Spain.

Neonicotinoids are insecticides used worldwide in phytosanitary and biocidal products and veterinary pharmaceuticals. Recently, some restrictions and bans have been imposed due to their adverse effects on nontarget invertebrates, including pollinators. Although they may have direct and indirect effects on wild vertebrates, few studies have assessed exposure to these compounds in wild birds, so our knowledge remains limited. In the present pilot study we have assessed the prevalence of seven neonicotinoid insecticides and some of their metabolites in whole blood samples from 19 European roller (Coracias garrulus) nestlings and five adult common kestrels (Falco tinnunculus) in an area treated with neonicotinoids to control the palm weevil (Rynchophorus ferrugineus) in southeastern Spain. One European roller nestling born in a palm tree was positive for thiamethoxam, with a concentration of 2.26 ng mL-1, but no residues of neonicotinoids or their metabolites were found in adult common kestrels. Future studies are needed to elucidate potential exposure to neonicotinoids at different times of the year. To our knowledge, this is the first report of the presence of thiamethoxam residues in whole blood of a wild bird species after its ban in Spain. Environ Toxicol Chem 2024;43:1836-1843. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Thiamethoxam Application Improves Yield and Drought Resistance of Potatoes (Solanum tuberosum L.).

(1) Background: Potato is the most important tuber crop in the world that can contribute to food security. However, the crop has been shown to be sensitive to drought and its yields decline significantly during successive periods of stress. Drought triggers a number of responses in potato, ranging from physiological changes to fluctuations in growth rates and yields. In light of global climate change, it is important to understand the effects of thiamethoxam on potato growth and yield under drought conditions. (2) Methods: The objective was to evaluate the impact of thiamethoxam on improving drought resistance and yield of potato under drought conditions. The drought-tolerant and sensitive-genotypes Qingshu No. 9 and Atlantic were used for a two-year pot experiment. Potato seeds were coated with 70% thiamethoxam before sowing (treatment group (T)), with a control group without treatment (NT). Two experimental treatments were applied: normal irrigation (ND) and drought stress (D). (3) Results: The results showed that root length, plant yield, chlorophyll content and superoxide dismutase (SOD) activity significantly increased under both genotypes, while malondialdehyde (MDA) and proline (Pro) content were reduced under thiamethoxam under drought stress. The best indicators were obtained in the comprehensive evaluation for the T-D treatment, suggesting that the application of thiamethoxam under drought stress was more effective than normal irrigation. (4) Conclusions: Our results suggest that the application of thiamethoxam improves potato growth, thereby increasing drought tolerance and potato yield. However, thiamethoxam is a neonicotinoid pesticide, and the limitation of this study is that it did not explore the ecological effects of thiamethoxam, which need to be systematically studied in the future. Moreover, considering the potential risks of thiamethoxam to the environment, specific agronomic measures to effectively degrade thiamethoxam residue should be taken when it is applied in agricultural production.

Persistence of foliar applied and pre-storage seed-treated insecticides in rice and its processed products

A field study was conducted to investigate the persistence of foliar-applied thiamethoxam 25% WG at a rate of 25 g ai ha−1 and chlorantraniliprole 18.5% SC at 30 g ai ha−1 in various parts of rice plants, including whole grain rice, brown rice, bran, husk, straw, and cooked rice. Liquid Chromatography-Mass spectrometry/Mass spectrometry was used for sample analysis. Chlorantraniliprole residues were found to persist in whole grains, bran, husk, and straw at the time of harvest, while thiamethoxam residue was not detected in harvested grains, processed products, or straw. The study concluded that foliar-applied chlorantraniliprole and thiamethoxam did not pose any dietary risk in cooked rice. In a pre-storage seed treatment study, thiamethoxam 30% FS at 3 mL kg−1 was evaluated against Angoumois grain moth infestation during storage. The seeds remained unharmed for nine months and exhibited significantly less moth damage (2.0%) even after twelve months of storage. Thiamethoxam residues persisted for more than one year in whole rice grain, brown rice, bran, and husk with seed treatment, with higher residue levels observed in bran and husk. Parboiling and cooking led to the degradation of thiamethoxam residues.

Effect of Thiamethoxam Insecticide on Productive Performance of Nile tilapia as well as Water Quality of Fish Tanks

Thiamethoxam (TMX) is a highly toxic systemic neonicotinoid pesticide and its entry into water bodies can greatly endanger human health and aquatic ecosystems. Little is known about the effect of thiamethoxam on Nile Tilapia. Particularly so this experiment was scheduled for three weeks to evaluate the toxic effects of thiamethoxam on productive performance of fish as well as water quality. The used insecticide was Actara 25 WG manufactured by Sygenta, Egypt and it was purchased from Egyptian Company for Seeds and Agricultural Chemicals. It composed of 250 g/kg Thiamethoxam. A total of 200 Oreochromis niloticus with an average initial weight of 15 ± 5 g have been obtained from a commercial fish farm in Kafr Elsheikh province, Egypt. Fish were randomly allotted to five replicated treatments and they were kept at a density of 10 fish / aquaria. Four different concentrations of the insecticide were tested with three replicates of fish for each treatment beside a control group where with no insecticide were used. Tested concentrations of studied insecticide was selected according to lethal concentration 50 (LC50) for Thiamethoxam was 500 mg/l. Statistical analysis of the recorded data clarified that the levels of pH, dissolved oxygen levels (DO), oxygen saturation percentage (DO%) and salinity were significantly different between thiamethoxam treated groups and the control group. In addition, there was a significant difference in final weight and weight gain of fish under experiment in all treatments when compared with the control group. In addition, the lowest significance in the final weight and weight gain was observed at the high chronic dose. Finally, there were no significant differences in mortalities between various treatment groups and the control group with exception to high subacute dose that showed the highest significance of all groups and it was clear that mortalities were increased with increasing thiamethoxam dose as no mortalities were observed in the control group. The present trial clearly showed the toxic effects of thiamethoxam on water quality of fish tank as well as performance and mortality rate in Nile tilapia fish that were live for three weeks in polluted water. Moreover, the result of the present study is of great public health importance because of thiamethoxam residue effects on human health.

Comprehensive effects of thiamethoxam from contaminated soil on lettuce growth and metabolism

The second-generation neonicotinoid thiamethoxam, is prevalent in soils because of its extensive application and persistence. However, the comprehensive effects of thiamethoxam residue in soils on cultivated plants are still poorly understood. This study examined variations of growth state, physiological parameters, antioxidant activity, and metabolites in lettuce after thiamethoxam exposure; the removal effects of different washing procedures were also investigated. The results indicated that thiamethoxam in soils significantly increased the fresh weight, seedling height and chlorophyll content in lettuce, and also altered its lipid, carbohydrate, nucleotide and amino acids composition based on untargeted metabolomics. KEGG pathway analysis uncovered a disruption of lipid pathways in lettuce exposed to both low and high concentrations of thiamethoxam treatments. In addition, the terminal residues of thiamethoxam in lettuce were below the corresponding maximum residue limits stipulated for China. The thiamethoxam removal rates achieved by common washing procedures in lettuce ranged from 26.9% to 42.6%. This study thus promotes the understanding of the potential food safety risk caused by residual thiamethoxam in soils.

MOF@Au NPs/aptamer fluorescent probe for the selective and sensitive detection of thiamethoxam

AbstractThe luminescence performance of fluorescent reagents plays a crucial role in fluorescence analysis. Therefore, in this study, a novel bi‐ligand Zn‐based metal–organic framework, Au nanoparticle (NP) fluorescent material was synthesized using a hydrothermal method with Zn as the metal source. Simultaneously, a DNA aptamer was introduced as a molecular recognition element to develop a Zn‐based MOF@Au NPs/DNA aptamer fluorescent probe for the ultra‐trace detection of thiamethoxam residues in agricultural products. The probe captured different concentrations of the target molecule, thiamethoxam, through the DNA aptamer, causing a conformational change in the DNA aptamer and bursting the fluorescence of the probe, therefore establishing a fluorometric method for thiamethoxam detection. This method is highly sensitive due to the excellent luminescence properties of the Zn‐based MOF@Au NPs, and the DNA aptamer can specifically recognize thiamethoxam, offering high selectivity. The linear range of the method was 2.5–6000 × 10−11 mol L−1, with a detection limit of 8.33 × 10−12 mol L−1. This method was applied to the determination of actual samples, such as bananas, and the spiked recovery rate was found to be in the range 84.05–109.07%. Overall, the proposed probe has high sensitivity, high selectivity, and easy operation for the detection of thiamethoxam residues in actual samples.

Residual Pattern of Chlorantraniliprole, Thiamethoxam, Flubendiamide and Deltamethrin in Tomato Fruit and Soil.

Tomato, Lycopersicon esculentum L. is grown widely as an important day-to-day demand vegetable. The crop is attacked by various polyphagous insect pests like tomato fruit borer, stink bug, cabbage looper, flea beetle, aphids, whitefly, two-spotted spider mite, etc., and oligophagous insects like leaf-miner, five-spotted hawkmoth, etc. To combat the damage and yield loss, various chemical insecticides were sprayed on tomatoes under field conditions. The residual pattern of insecticides like chlorantraniliprole, thiamethoxam, flubendiamide, and deltamethrin residues was studied following applications of chlorantraniliprole 18.5% SC (Coragen) @ 30g a.i./ha, thiamethoxam 25% WG (Actara) @ 50g a.i./ha, flubendiamide 39.35M/M SC (Fame) @ 48g a.i./ha and deltamethrin 2.8% EC (Decis 100) @ 12.5g a.i./ha using Reverse Phase High-Performance Liquid Chromatography (RP-HPLC). Fruit samples were collected at 0 (1h after application), 1, 2, 3, 5, 7 days and at harvest time. All the residues of insecticides such as chlorantraniliprole (0.09mg kg- 1), thiamethoxam (0.03mg kg- 1), flubendiamide (0.02mg kg- 1), and deltamethrin (0.01mg kg- 1) were persisted up to 5th day. There were no residues found at harvest time. The residues of chlorantraniliprole and deltamethrin persisted up to 3rd day of spraying whereas the residues of flubendiamide and thiamethoxam were not detected on the same day in the soil.

Harvest Time Residues of Imidacloprid and Thiamethoxam in Black Gram

Imidacloprid and thiamethoxam insecticides have been important tools for controlling pests in black gram. The use of these pesticides on various crops has increased rapidly resulting the produce containing toxic residues from the application of these insecticides and in some cases the concentrations are above maximum residue limit. The prudent usage of synthetic insecticides resulted in secondary pest-outbreaks, resistance development, food, and ecosystem adulteration and so on which pose serious threat to human beings. However, food safety issues related to pesticide residues are important to consider with a food crop such as black gram which causes no harm to consumers and are permissible in domestic and international trade. Therefore, the objective of this study was to analyse harvest time residues of imidacloprid and thiamethoxam in black gram. The study was conducted during the summer season 2021 at Research Farm, Tirhut College of Agriculture, Dholi (Muzaffarpur)–Bihar. The crop (cultivar SML 613) was sown on February, 27, 2021. Insecticides were applied at 30 days after sowing which was followed by two successive sprays at 15 days intervals following the recommended dose of 25 g a.i. ha-1 for both the insecticides. Sample aliquots were analysed using HPLC (High Pressure Liquid Chromatography) equipped with Photo Diode–Array Detector (PDA). The sample taken at harvest with a pre–harvest interval (PHI) of 28 days did not reveal the residues of imidacloprid and thiamethoxam in black gram seeds at Limit of Quantification (LOQ) of 0.05 mg kg-1.

Assessing the effectiveness of imidacloprid and thiamethoxam via root irrigation against Megalurothrips usitatus (Thysanoptera: Thripidae) and its residual effects on cowpea.

Systemic neonicotinoid insecticides (NEOs) applied by seed-treatment or root application have emerged as a prevalent strategy for early-season insect pest management. This research investigated the effectiveness of imidacloprid and thiamethoxam, administered through root irrigation, in managing thrips in cowpea [Vigna unguiculata (Linn.) Walp.], and the residual properties of both insecticides in cowpea and soil. The results show that thrips density depends on the application rate of insecticides. At the maximum application rate (1,500 µg/ml, active ingredient), imidacloprid and thiamethoxam controlled thrips densities below the economic injury level (EIL, the EIL of thrips on cowpea was 7/flower) for 20 days and 25 days with the density of 6.90 and 6.93/flower at the end of the periods, respectively. Imidacloprid and thiamethoxam residues decreased gradually over time and decreased sharply after 15 days after treatment (DAT), the 2 insecticides were not detected (<0.001 mg/kg) at 45 DAT. According to our findings, the application of imidacloprid and thiamethoxam via root irrigation proved residual control lasting up to 20-25 days for controlling thrips damage at experimental rates, with a strong association to their residual presence in cowpea (0.6223 < R2 < 0.9545). Considering the persistence of the imidacloprid and thiamethoxam, the maximum tested application rate (1,500 µg/ml) was recommended. As the residues of imidacloprid and thiamethoxam were undetectable in cowpea pods at all tested rates, it may be suggested that the use of each insecticide is safe for consumers and effective against thrips, and could be considered for integrated thrips management in the cowpea ecosystem.

Translocation and dissipation of thiamethoxam applied by root irrigation in tomato plant-soil system.

Thiamethoxam (TMX) has been registered for use on a wide range of crops due to its versatile application methods, however, there is limited literature evaluating the residue behaviors of TMX applied through root irrigation. In this study, the uptake and translocation of TMX, its degradation to clothianidin (CLO), and dissipation in the tomato plant-soil system were conducted. TMX applied by root irrigation was transferable within the tomato plant, including stems, leaves, and fruits at different heights. TMX concentrations in the four sections of stems were ordered as Clower > Cmid > Cupper > Ctop, while in the leaves were ordered as Ctop > Cupper > Cmid > Clower. The degradation product CLO was detected in the tomato plant, and concentrations of CLO were even higher than those of TMX in the leaves. The translocation factor (TF) of TMX in the same section generally followed the order of TFleaf > TFstem > TFfruit. Residues of TMX and CLO in tomato on 7 days after application were below maximum residue limits (MRLs) in China and Codex Alimentarius Commission(CAC). This study promotes the evaluation of TMX applied through root irrigation for use in the tomato system from a dietary safety perspective.

Effects of Thiamethoxam and Fenvalerate Residue Levels on Light-Stable Isotopes of Leafy Vegetables.

Accurate identification of the rational and standardized use of pesticides is important for the sustainable development of agriculture while maintaining a high quality. The insecticides thiamethoxam and fenvalerate and the vegetables spinach, cabbage, and lettuce were used here as study objects. Descriptive analysis and primary reaction kinetic equations were used to analyze the changes in metabolic residues of the two insecticides after different numbers of application in three vegetables. The effects of pesticide residue levels on the δ13C, δ15N, δ2H, and δ18O values of vegetables were analyzed by one-way analysis of variance and correlation analysis. Partial least squares discriminant analysis (PLS-DA) was applied to build discrimination models of the vegetables with different pesticide residues based on stable isotopes. The results showed that the first degradation residues of thiamethoxam and fenvalerate in spinach, cabbage, and lettuce conformed to primary reaction kinetic equations, but the degradation half-lives were long, and accumulation occurred in the second application. The differences in the four stable isotope ratios in the control group of the three vegetables were statistically significant, and two-thirds of the stable isotope ratios in the three vegetables with different numbers of pesticide applications were significantly different. The δ13C and δ15N values of spinach, the δ13C, δ15N, and δ2H values of cabbage, and the δ13C, δ15N, δ2H, and δ18O values of lettuce were significantly correlated with different residues of thiamethoxam and/or fenvalerate applications. The control groups of the three vegetables, spinach-thiamethoxam-first, spinach-thiamethoxam-second, cabbage-thiamethoxam-second, cabbage-fenvalerate-first, and lettuce-thiamethoxam-first, were fully identified by PLS-DA models, while the identification models of other vegetables containing pesticide residues still need to be further improved. The results provide technical support for identifying the rational use of pesticides in vegetables and provide a reference method for guaranteeing the authenticity of green and organic vegetables.

Dissipation, Bioconcentration and Dietary Risk Assessment of Thiamethoxam and Its Metabolites in Agaricus bisporus and Substrates under Different Application Methods

In order to acquire scientific evidence for the application of thiamethoxam (TMX) in Agaricus bisporus cultivation, residue and dissipation experiments for field trials were performed with the application of TMX in compost and casing soil, respectively. An effective QuEChERS method was established to analyze TMX and its two metabolites, clothianidin (CLO) and thiamethoxam-urea (TMX-urea), in compost, casing soil, and fruiting bodies. The results indicated that the TMX dissipation half-lives (t1/2) at dosages of 10 and 50 mg kg−1 were 19.74 d (day) and 28.87 d in compost and 33.54 d and 42.59 d in casing soil, individually. TMX, CLO, and TMX-urea were observed after TMX application in compost and casing soil. For TMX applied to the casing soil, only TMX residues were detected in fruiting bodies with bioconcentration factors (BCFs) of 0.0003~0.0009. In addition, both the chronic risk quotient (RQ) and acute risk quotient (HQ) values of TMX in fruiting bodies were far less than 1, which means the dietary health risks to humans were acceptable. However, in the TMX application to the compost, these analytes were not detected in the fruiting bodies. This suggested that the application of TMX in compost was safer than in casing soil during A. bisporus cultivation.

Impact of Seed Treatment with Imidacloprid, Clothianidin and Thiamethoxam on Soil, Plants, Bees and Hive Products

This paper presents studies performed for the monitoring of imidacloprid, clothianidin and thiamethoxam residues applied as seed treatment in rapeseed (Brassica napus ssp. oleifera), maize (Zea mays) and sunflower crops (Helianthus annuus). The experiments were located in representative areas of the mentioned crops. Residue levels were determined in plant samples at different phenological development stages, including flowers, as well as in bees and hive products (pollen, honeycomb, honey) by liquid chromatography/tandem mass spectroscopy (LC-MS/MS). The analyses were performed in ISO 17025-accredited laboratories, referring to the limit of quantification (LOQ), characteristic of the method used to determine the residues. In 2019, the percentage of samples that contained residues of the three substances, applied to the seed, was 16.39%, representing 20 samples out of the total of 122 analyzed samples. In 2020, 10 samples contained neonicotinoid residues above the LOQ, including 5 soil samples and 5 plant samples, representing 6.17% of the total samples. In 2021, from 149 samples with neonicotinoid applied as seed treatment, residues were identified in 12 soil samples and 11 plant samples, representing 15.43% of the total number of samples. In 2022, only 12 soil samples and 1 pasture sample contained residues above the LOQ. The results show that the highest percentage of samples with residues above the LOQ was recorded by the soil samples, while the flower and bee samples had the lowest percentages of samples with residues above the LOQ; no residues of the three neonicotinoid substances were identified in the honey samples.

Photochemical advanced oxidative process treatment effect on the pesticide residues reduction and quality changes in dried red peppers

Pesticide residues in crops are widely monitored, and the residue reduction techniques at the post-harvest stage are important to maintain food safety. In dried crops, pesticide residues can be concentrated after dehydration, which increases concerns regarding residue risk. Therefore, the residue reduction effects of ultraviolet (UV), ozone, and photochemical advanced oxidative process (pAOP) were investigated for dried peppers at the post-harvest stage. UV254 treatment reduced 59.7% of the residue concentration on average, while UV360 showed a reduction of only 13.3% under 9.6 W m−2 of UV exposure for 24 h. Gaseous ozone treatments reduced the residue concentrations up to 57.9% on average. In contrast, the pAOP treatment reduced the concentration up to 97% and was superior to UV or ozone treatment alone. Increased drying temperature under pAOP condition resulted in higher reduction ratios at 40–80 °C. The pAOP conditions with 12 and 24 µmol/mol of ozone and UV254 irradiation for 24–48 h reduced the residue concentrations to 39–67%. Particularly, difenoconazole, fludioxonil, imidacloprid, and thiamethoxam residue concentrations were drastically reduced by over 50% under 12 µmol/mol ozone of the pAOP condition, while carbendazim, fluquinconazole, and pyrimethanil were relatively stable and their concentrations reduced below 50% under 24 µmol/mol ozone of the pAOP treatment. Various drying-related quality parameters of drying peppers such as water-soluble color, capsanthin, capsaicinoids, acid value, peroxide value, and thiobarbituric acid value were slightly altered, but not significantly, under 12 µmol/mol ozone of the pAOP condition, while the peroxide value was significantly altered under the higher ozone conditions. Therefore, pAOP treatment combined with gaseous ozone can be used for reducing residual pesticides in peppers without greatly reducing quality.

Dust abraded from thiamethoxam-treated seed during sowing: Refining the risk assessment for native bees in Brazil.

During sowing using pneumatic machinery, dust may be abraded from pesticide-treated seed and contaminate adjacent bee-attractive off-crop areas. This study quantified the risk to native bees of dust released during sowing of Brazilian crop seeds treated with a thiamethoxam formulation (Cruiser 350FS). To address toxicity to native bees, adult acute contact LD50 data for thiamethoxam were collated from the literature, a species sensitivity distribution generated, and the HD5 calculated. The LD50 HD5 was used to refine the default safety factor applied to the honeybee acute contact LD50 from 10 to 5.45 for thiamethoxam. Crop-specific abraded dust data (Heubach dust and Heubach AI) were generated for seeds treated with Cruiser 350FS sourced from on-farm and industrial facilities. The mean Heubach dust levels was ranked as cotton = maize > sunflower = soybean > drybean. There was no correlation between the measured residues of thiamethoxam (Heubach AI) and those estimated in dust based on the thiamethoxam content of Cruiser 350FS. A hazard quotient (HQ) for each crop (based on application rate, the default dust deposition factor, and the honeybee contact LD50/10) identified risks during sowing for all crops. Refinement of the application rate with the measured 90th percentile Heubach dust (assuming 100% thiamethoxam) resulted in sowing of industrially treated soybean and on-farm treated cotton being identified as risks. Further refinement using either the measured 90th percentile Heubach AI or the acute contact LD50 (HD5 ) resulted in sowing of all crops treated with Cruiser 350FS as being identified as low risk. Similar high quality seed treatment should be demonstrated for other formulations containing insecticides with high toxicity to bees. Data on dust drift from machinery and crops more representative of those in Brazil may allow further refinement of the default dust deposition value of 17% used in this study. Integr Environ Assess Manag 2023;19:1361-1373. © 2023 SETAC.

Screening and Evaluation of Thiamethoxam Aptamer Based on Pressurized GO-SELEX and Its Sensor Application

Thiamethoxam, a nicotinic pesticide used worldwide, can cause great harm to the environment and even to human health, and aptamers, known as chemical antibodies, have high affinity and specificity for the target, as well as great potential in detecting small molecules such as pesticides. In this paper, we report a highly sensitive biosensor system for thiamethoxam residue detection based on aptamer technology. After 15 rounds of screening with the pressurized GO-SELEX technology, we found that the aptamer libraries of the 5th and 9th rounds showed high affinity by the capture method. Four candidate aptamers were obtained by high-throughput sequencing and secondary structure prediction. Among them, the aptamer named Thi-5R-18 from the 5th round was demonstrated to possess the highest affinity by isothermal titration calorimetry, with a dissociation constant (Kd) of 4.935 × 10-5 M. The results of molecular docking showed that thiamethoxam and Thi-5R-18 were combined with bases G-15, A-19, and T-71 through hydrogen bonding and π-π interaction.Thi-5R-18 was used as a recognition element to construct a AuNPs colorimetric aptasensor, achieving an ultralow detection limit of 0.37 nM. More importantly, this colorimetric aptasensor can be used for quantitative detection of thiamethoxam on tea leaves, with a recovery of 96.94%~105.86%. This study provides a highly sensitive biosensor for detection of thiamethoxam residue.

LC-MS/MS ve GC-MS ile Türkiye menşeli patateslerde insektisit kalıntılarının araştırılması ve sağlık risk değerlendirmesi

Insecticide, acaricide, nematicide and metabolite residues were assayed in 104 potato samples collected from local markets in Tokat, Türkiye in 2022 and the potential health risk for consumers assessed. Analytical method verification was performed for 135 pesticide active substances in potato matrices by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry. Matrix-matched calibration curves were constructed and good linearity was obtained with a coefficient of determination between 0.990 and 0.999. Average recoveries varied from 73.2 to 119.6%. Repeatability and intra-laboratory reproducibility conditions of the method expressed as %RSD were less than 20%. These figures were within the SANTE/11312/2021 recovery limits (70-120%) and the values specified for the repeatability (RSD ≤ 20%). The limits of quantification were lower than the maximum residue limits set by the European Union for the potato. No pesticide residues were found at detectable limits in 93 samples. Two samples contained residues below the maximum residue limit (MRL), while nine samples contained residues above the MRLs. Clothianidin and thiamethoxam residues detected in one sample, while acetamiprid were detected in nine samples. The health risk assessment study indicated that potato consumption was safe for consumers.

Determination of thiamethoxam residues and dissipation kinetic in tomato plants and its efficacy against Bemisia tabaci under open field eco system.

Whitefly, Bemisia tabaci cause important losses for many crops especially tomato, therefore farmers often use many chemical insecticides which had dangerous side effects on human beings and environment, thus there are need to determine the residues of these chemicals in plant . The dissipation of thiamethoxam in tomato leaves and fruits followed the first order kinetics; Half-lives were 2.91 and 3.15 days for fruits and leaves, respectively. The residues of thiamethoxam were determined using a QuEChERS method with HPLC-DAD and it was 0.14 mg/ kg in fruits after 7 days of treatment and less than the maximum residue limit (MRL 0.2 mg/kg. The residue in leaves was more than in fruits. Seedlings produced from treated seeds were more resistant to different stages of the whitefly population and protect tomato plants from whitefly infestation for 6-10 weeks after transplanting. The three sprays of thiamethoxam increased the reduction percentage of B. tabaci stages and the highest increase was recorded after the third spray in egg, nymph, and adult stages. It could be recommend that Thiamethoxam is considered an unconventional insecticide appropriate for B. tabaci control and safe for humans and the environment.