Comparation study on the metabolism destination of neonicotinoid and organophosphate insecticides in tea plant (Camellia sinensis L.)

Development of a hydrophilic-lipophilic-balanced copolymer@zirconium-based metal-organic framework-based solid-phase microextraction probe for the trace determination of organophosphorus pesticides in tea infusions

Organophosphorus pesticides (OPPs) present in tea infusions pose a serious threat to human health. In this study, a sensitive method for the determination of OPPs was developed based on a direct-immersion solid-phase microextraction (DI-SPME) probe. By fine adjustment of the ratio and one-step polymerization of dihydroxy-functionalized zirconium-based metal-organic framework UiO-66-(OH)2 and divinylbenzene-N-vinyl pyrrolidone (DVB-NVP) microspheres, the DVB-NVP@ UiO-66-(OH)2 (D-N@U) composite with an optimal hydrophilic-lipophilic balance (HLB) was achieved. Furthermore, D-N@U was adhesively bonded to stainless-steel wires to fabricate a DI-SPME probe. OPPs, especially those with nonpolar properties characterized by a high octanol-water partition coefficient (log KOW), were selectively and efficiently enriched on the D-N@U-coated DI-SPME probe from tea infusions. Coupled with a gas chromatography-flame photometric detector, the as-fabricated D-N@U-coated DI-SPME probe achieved good performance for OPPs analysis with a wide linear dynamic range of 0.10-500.00 μg/L and low detection limits of 1.96-6.69 ng/L. Moreover, in spiked samples, the recoveries and relative standard deviations were in the ranges of 73.12%-101.20 % and 1.03%-6.56 %, respectively. Owing to its simple operation, high extraction efficiency, and high sensitivity, this approach has great potential for the rapid determination of multiple pesticide trace-level residues in food.

Microbial degradation mechanism and pathway of the insecticide thiamethoxam by isolated Bacillus Cereus from activated sludge

The high water solubility and ecotoxicity of thiamethoxam (TMX) is a potential hazard to ecosystems and human health. Here, a strain of Bacillus cereus with high TMX degradation activity was isolated from the sediment of the A2O process in the wastewater treatment plant and was able to utilize TMX as its sole carbon source. Under different environmental conditions, the degradation efficiency of TMX by Bacillus cereus-S1 (strain S1) ranged from 41.0% to 68.9% after 216 h. The optimum degradation conditions were DO = 3.5 mg/L and pH 9.0. The addition of an appropriate carbon-to-nitrogen ratio could accelerate the degradation of TMX. A plausible biodegradation pathway has been proposed based on the identified metabolites and their corresponding degradation pathways. TMX can be directly converted into Clothianidin (CLO), TMX-dm-hydroxyl and TMX-Urea by a series of reactions such as demethylation, oxadiazine ring cleavage and C=N substitution by hydroxy group. The main products were TMX-dm-hydroxyl and TMX-Urea, the amount of CLO production is relatively small. This study aims to provide a new approach for efficient degradation of TMX; furthermore, strain S1 is a promising biological source for in situ remediation of TMX contamination.

Non-acute exposure of neonicotinoids, health risk assessment, and evidence integration: a systematic review

Neonicotinoid pesticides are utilized against an extensive range of insects. A growing body of evidence supports that these neuro-active insecticides are classified as toxicants in invertebrates. However, there is limited published data regarding their toxicity in vertebrates and mammals. the current systematic review is focused on the up-to-date knowledge available for several neonicotinoid pesticides and their non-acute toxicity on rodents and human physiology. Oral lethal dose 50 (LD50) of seven neonicotinoids (i.e. imidacloprid, acetamiprid, clothianidin, dinotefuran, thiamethoxam, thiacloprid, and nitenpyram) was initially identified. Subsequently, a screening of the literature was conducted to collect information about non-acute exposure to these insecticides. 99 studies were included and assessed for their risk of bias and level of evidence according to the Office of Health and Translation (OHAT) framework. All the 99 included papers indicate evidence of reproductive toxicity, hepatotoxicity, nephrotoxicity, neurotoxicity, immunotoxicity, and oxidative stress induction with a high level of evidence in the health effect of rodents and a moderate level of evidence for human health. The most studied type of these insecticides among 99 papers was imidacloprid (55 papers), followed by acetamiprid (22 papers), clothianidin (21 papers), and thiacloprid (11 papers). While 10 of 99 papers assessed the relationship between clothianidin, thiamethoxam, dinotefuran, and nitenpyram, showing evidence of liver injury, dysfunctions of oxidative stress markers in the reproductive system, and intestinal toxicity. This systematic review provides a comprehensive overview of the potential risks caused by neonicotinoid insecticides to humans and rodents with salient health effects. However, further research is needed to better emphasize and understand the patho-physiological mechanisms of these insecticides, taking into account various factors that can influence their toxicity.

Phytodegradation of neonicotinoids in Cyperus papyrus from enzymatic and transcriptomic perspectives

Neonicotinoids are widely used but environmentally hazardous insecticides. Constructed wetlands offer potential for neonicotinoid removal, but the corresponding metabolic pathways and mechanisms in wetland plants are incompletely understood. This study investigated the fate of six neonicotinoids and their metabolites in Cyperus papyrus, a common wetland plant, and the underlying metabolic mechanisms through enzymatic and transcriptomic analyses. Neonicotinoids were absorbed by roots and translocated upward, causing high levels in shoots. Concentrations of neonicotinoids and their metabolites declined to their minimum at day 28 of exposure. Nitro reduction, hydroxylation, and demethylation were the major metabolic reactions with which C. papyrus responded to neonicotinoids. These reactions may be mediated by cytochrome P450 enzyme, aldehyde oxidase, glutathione-disulfide reductase, and glucuronate reductase. The toxicity of neonicotinoids in C. papyrus was evaluated according to the peroxidase and catalase enzymatic activities. Transcriptomic analysis revealed that differentially expressed genes (DEGs) mainly encoded proteins related to immune processes and cell growth regulation. Co-expression correlation analysis of DEGs revealed that the genes encoding P450s, peroxidase and glutathione S-transferase were the key functional genes. This study elucidates the stress response and degradation mechanism of neonicotinoids in wetland plants, providing new insights into the phytoremediation of organic contaminants in constructed wetlands.

Pyrrolizidine Alkaloids in Tea (Camellia sinensis L.) from Weeds through Weed-Soil-Tea Transfer and Risk Assessment of Tea Intake

Pyrrolizidine alkaloids (PAs) have been detected in tea and can threaten human health. However, the specific source of PAs in tea is still unclear. Here, 88 dried tea products collected from six major tea-producing areas in Anhui Province, China, were analyzed. The detection frequency was 76%. The content of total PAs in dried tea was between 1.1 and 90.5 μg/kg, which was all below the MRL recommended by the European Union (150 μg/kg). In the Shexian tea garden, PAs in the weeds and weed rhizospheric soil around tea plants and the fresh tea leaves were analyzed. Intermedine (Im), intermedine-N-oxide (ImNO), and jacobine-N-oxide (JbNO) were transferred through the weed-to-soil-to-tea route into the fresh tea leaves; only Im and ImNO were detected in dried tea samples. Potential risk of the total PAs in the tea infusion was assessed according to the margin of exposure method, and it might be a low concern for public health.

Uptake and translocation of organic pollutants in Camellia sinensis (L.): a review

Camellia sinensis (L.) is a perennial evergreen woody plant with the potential for environmental pollution due to its unique growth environment and extended growth cycle. Pollution sources and pathways for tea plants encompass various factors, including atmospheric deposition, agricultural inputs of chemical fertilizers and pesticide, uptake from soil, and sewage irrigation. During the cultivation phase, Camellia sinensis (L.) can absorb organic pollutants through its roots and leaves. This review provides an overview of the uptake and translocation mechanisms involving the absorption of polycyclic aromatic hydrocarbons (PAHs), pesticides, anthraquinone (AQ), perchlorate, and other organic pollutants by tea plant roots. Additionally, we summarize how fresh tea leaves can be impacted by spraying pesticide and atmospheric sedimentation. In conclusion, this review highlights current research progress in understanding the pollution risks associated with Camellia sinensis (L.) and its products, emphasizing the need for further investigation and providing insights into potential future directions for research in this field.

Are the issues involving acephate already resolved? A scientometric review

Acephate is a pesticide classified as moderately toxic, and its metabolite methamidophos is highly toxic for mammals and birds; even so, it is one of the most used insecticides in pest control for agricultural and domestic use. Acephate toxicity affects both target and non-target organisms and causes serious damage to the environment. There are several studies on different perspectives of acephate, such as monitoring, toxicity, and modeling. In this sense, this research aims to identify the structure of intellectual production on acephate and analyze the gaps and trends of scientific production on acephate through a scientometric analysis. The data was obtained from the Web of Science database, and after the refinement, 1.085 documents were used. A temporal pattern of the main research objectives is displayed. Most selected studies evaluated acephate efficiency, followed by toxicity and residue detection methods. The USA, China, India, Brazil, and Japan had the highest number of publications on acephate. The keywords most utilized were pesticides, toxicity, insecticide resistance, and residue. Research involving acephate requires greater attention from areas such as ecotoxicology, biochemistry, genetics, and biotechnology. There needed to be more discussions on chronic toxicity, genotoxicity, and cytotoxicity. Moreover, few studies about metabolic and biochemical pathways and genes related to acephate action and biodegradation were scarce.

A critical review on the accumulation of neonicotinoid insecticides in pollen and nectar: Influencing factors and implications for pollinator exposure

Neonicotinoids are a class of neuro-active insecticides widely used to protect major crops, primarily because of their broad-spectrum insecticidal activity and low vertebrate toxicity. Owing to their systemic nature, plants readily take up neonicotinoids and translocate them through roots, leaves, and other tissues to flowers (pollen and nectar) that serve as a critical point of exposure to pollinators foraging on treated plants. The growing evidence for potential adverse effects on non-target species, especially pollinators, and persistence has raised serious concerns, as these pesticides are increasingly prevalent in terrestrial and aquatic systems. Despite increasing research efforts, our understanding of the potential toxicity of neonicotinoids and the risks they pose to non-target species remains limited. Therefore, this critical review provides a succinct evaluation of the uptake, translocation, and accumulation processes of neonicotinoids in plants and the factors that may affect the eventual build-up of neonicotinoids in pollen and nectar. The role of plant species, as well as the physicochemical properties and application methods of neonicotinoids is discussed. Potential knowledge gaps are identified, and questions meriting future research are suggested for improving our understanding of the relationship between neonicotinoid residues in plants and exposure to pollinators.

Exogenous tannic acid relieves imidacloprid-induced oxidative stress in tea tree by activating antioxidant responses and the flavonoid biosynthetic pathway

Pesticide stress on plants is receiving increased scrutiny due to its effect on plant secondary metabolism and nutritional quality. Tannic acid (TA) is a natural polyphenolic compound showing excellent antioxidant properties and is involved in alleviating stress. The present study thoroughly investigated the effects and mechanism of exogenous TA on relieving imidacloprid (IMI) stress in tea plants. Our research found that TA(10 mg/L) activated the antioxidant defense system, enhanced the antioxidant ability, reduced the accumulation of ROS and membrane peroxidation, and notably promoted tea plant tolerance to imidacloprid stress. Additionally, TA boosted photosynthetic capacity, strengthened the accumulation of nutrients. regulated detoxification metabolism, and accelerated the digestion and metabolism of imidacloprid in tea plants. Furthermore, TA induced significant changes in 90 important metabolites in tea, targeting 17 metabolic pathways through extensively targeted metabolomics. Specifically, TA activated the flavonoid biosynthetic pathway, resulting in a 1.3- to 3.1-fold increase in the levels of 17 compounds and a 1.5- to 63.8-fold increase in the transcript level of related genes, such as ANR, LAR and CHS in this pathway. As a potential tea health activator, TA alleviates the oxidative damage caused by imidacloprid and improves the yield and quality of tea under pesticide stress.

Metabolic responses of tea (Camellia sinensis L.) to the insecticide thiamethoxam

BACKGROUND

Thiamethoxam (TMX) is insecticidal, but also can trigger physiological and metabolic reactions of plant cycles. The objective of this work was to evaluate the physiological and metabolic effect of TMX on tea plants and its potential benefits.

RESULTS

In this study, dose of TMX (0.09, 0.135 and 0.18 kg a.i./ha) were tested. Except for peroxidase (POD) and glutathione S-transferase (GST), chlorophyll, carotenoid, catalase (CAT) and malondialdehyde (MDA) were significantly affected compared with the controls. The CAT activity was increased by 3.38, 1.71, 2.91 times, respectively, under three doses of TMX treatment. The metabolic response between TMX treatment and control groups on the third day was compared using a widely targeted metabolomics. A total of 97 different metabolites were identified, including benzenoids, flavonoids, lipids and lipid-like molecules, organic acids and derivatives, organic nitrogen compounds, organic oxygen compounds, organoheterocyclic compounds, phenylpropanoids and polyketides, and others. Those metabolites were mapped on the perturbed metabolic pathways. The results demonstrated that the most perturbation occurred in flavone and flavonol biosynthesis. The beneficial secondary metabolites luteolin and kaempferol were upregulated 1.46 and 1.31 times respectively, which protect plants from biotic and abiotic stresses. Molecular docking models suggest interactions between TMX and flavonoid 3-O-glucosyltransferase.

CONCLUSION

Thiamethoxam spray positively promoted the physiological and metabolic response of tea plants. And this work also provided the useful information of TMX metabolism in tea plants as well as rational application of insecticides. © 2023 Society of Chemical Industry.

Pyrrolizidine-producing weeds in tea gardens as an indicator of alkaloids in tea

Pyrrolizidine alkaloids (PAs) can be transferred between plants via soil. Indicators of PAs in tea products are useful for tea garden management. In the present work a total of 37 weed species, 37 weed rhizospheric soils and 24 fresh tea leaf samples were collected from tea gardens, in which PAs were detected in 35 weeds species, 21 soil samples and 10 fresh tea leaves samples. In Shexian tea garden, 12.9 μg/kg of intermedine (Im) in one bud plus three leaves, 1.40 and 14.6 μg/kg of intermedine-N-oxide (ImNO) in one bud plus two leaves and one bud plus three leaves were detected, which were transferred from the PA-producing weeds via soil. However, no PAs were detected in fresh tea leaves collected from Langxi tea garden. The results indicated that synthesis of PAs in weeds and their transfer through the weed-soil-fresh tea leaf route varied with soil environments in different tea gardens.

Suspect screening strategy for pesticide application history based on characteristics of trace metabolites

Pesticides are widely used to protect crops but can also threaten public health as they can remain in the environment for a long time. Additionally, some transformation products (TPs) of unknown toxicity, stability, or bioaccumulation properties can further be formed from the hydrolysis, photolysis and biodegradation of pesticides. The identification and quantification of those TPs can be challenging for environmental regulation and risk assessment due to a limited understanding about them. In this study, a suspect screening strategy for pesticide application history was developed and then used to organic products (tea). Liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) was used to screen and identify the TPs in crops and their toxicity was subsequently predicted with the open-source software (ECOSAR and admetSAR). Finally, the SIRIUS software was applied and 142 TPs from 20 pesticides were identified in tea plants based on the fragmentation-degradation relationship. Of these, standards (level 1) and 53 were considered as tentatively identified (levels 2a and 2b). Some TPs were also found to be present in tea plants and soil after 65 days, thus indicating higher persistency or stability than parent pesticides. While others from diafenthiuron and neonicotinoids had higher predicted toxicity of daphnid, and demonstrated positive for honeybee toxicity. Suspect screening is a powerful tool to screen pesticide TPs on the complex matrix of crops. Such screening can provide potential evidence of pesticide application, especially in cases of illegal practices in organic farming.

Dissipative behavior, residual pattern, and risk assessment of four pesticides and their metabolites during tea cultivation, processing and infusion

BACKGROUND

In recent years, metabolic products of pesticides have gained much attention due to their substantial characteristics as organic pollutants. So far, the behavior and metabolite levels of pesticide metabolites in crops have not been characterized well. In the present study, four registered pesticides (imidacloprid, diafenthiuron, malathion and chlorothalonil) were applied on tea plants in Fujian and Sichuan to characterize their metabolites residue pattern and dietary risk.

RESULTS

Four pesticides dissipated first-order kinetics in the fresh tea leaves with the half-lives of 1.4-3.8 days. Nine metabolites were detected in the fresh tea leaves and green tea after processing. The metabolites residues showed an increasing trend first and then declined after treatment, and reached the maximum near the half-lives of pesticide. Compared with the parent pesticide, the total residue and acute risk (included the metabolites) increased by 1.7-105.2 times. Some metabolites, especially those whose parent pesticides have high water solubility and low Log Kow, will be more easily transferred to tea infusion.

CONCLUSION

Pesticides were metabolized rapidly on tea plants after application, but the production of metabolites increased the health risk of tea consumption. These results could provide insights to use the pesticides in tea gardens and risk monitoring after application. © 2022 Society of Chemical Industry.

Integrated approach for the analysis of neonicotinoids in fruits and food matrices

We searched for five neonicotenoids (namely acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam) in 67 samples of fruits, leaves, pollen and honey via HPLC-MS by employing QueChERs for extraction and purification. Clothianidin was never detected, while imidacloprid was identified in apple (9.2 µg/kg) and pollen (18-28 µg/Kg), thiacloprid in peaches (21-35 µg/kg) and acetamiprid was identified in the hazel leaves (1266 µg/kg), honey (13-26 µg /Kg) and pollen (11-24 µg/kg). Since the levels found of acetamiprid in hazel, honey and pollen were concerning, we accomplished a study to identify and characterize the possible transformation products via a laboratory simulation. The methodology exploited the analysis by HPLC-HRMS and its application in all matrices. We identify twelve transformation products, whose formation involved dimerization, hydroxylation, oxidation, demethylation and cleavage of the molecule. Three of them were also detected in hazel leaves.

Multi-residue analytical method development and risk assessment of 56 pesticides and their metabolites in tea by chromatography tandem mass spectroscopy

A modified QuEChERS method coupled to chromatography tandem mass spectroscopy was established and used to identify 56 pesticides and 21 metabolites residues in tea samples. The average recoveries for the target compounds ranged from 71% to 109% with RSDs of 1-17%. Pesticides and metabolites residues in 248 tea samples from China were investigated by the developed method, and the dietary intake risk for consumers was estimated. The results showed that 36 pesticides and 14 metabolites were detected with concentrations of 0.0050-7.7 mg/kg. There are unlikely to present a public health concern for Chinese consumers. The acute risk of pesticides would be exaggerated when calculated by the residue level in tea instead of tea infusion. The unauthorized and banned pesticide contributed to the chronic and acute hazard index by 68% and 36%, respectively. The cumulative risk of residual pesticides and their metabolites on human health deserve further attention.

Dissipation and transformation of the diamide insecticide cyantraniliprole in ornamental snapdragon (Antirrhinum majus)

Dissipation and transformation of cyantraniliprole, a new diamide class of insecticides, were investigated under greenhouse conditions, using snapdragon (Antirrhinum majus) as the model plant. Dissipation of cyantraniliprole in treated leaves was found to be dependent upon application methods (foliar spray versus soil drench) and doses (high versus low dose), with the parent insecticide being the major residue at various sampling points. A high-dose foliar application resulted in pesticide residue of 6.7-23.8 μg/g foliar fresh weight over 8 weeks of treatments, while in soil drench treatment the residue varied from 0.8 to 1.4 μg/g. However, the residue contents were similar between the two application methods at a low application dose. The transformation pathways of cyantraniliprole were primarily intramolecular rearrangements, with IN-J9Z38 being the major metabolite across treatments. Several other metabolites were also identified, some of which were unique to the application methods. Out of total 26 metabolites tentatively identified in this study, 10 metabolites were unique to foliar application, while six metabolites were unique to soil drench. In addition to plant-mediated biotransformation, photodegradation of the parent compound was identified as a potential mechanism in foliar application.

Pesticide Residue Behavior and Risk Assessment in Celery after Se Nanoparticles Application

This study investigates pesticide levels in celery, and compares their degradation, dissipation, distribution, and dietary risk after spraying with selenium (Se) nanoparticles. Abamectin, imidacloprid, acetamiprid, thiamethoxam, and lambda-cyhalothrin were sprayed at 1.6, 6.8, 2.0, 1.0, and 0.7 g a.i. ha⁻¹ followed by a 2 g·ha⁻¹ Se nanoparticle application during the growing period. Thiamethoxam, abamectin, imidacloprid, lambda-cyhalothrin, and acetamiprid in celery degraded following a first order kinetic model after 2 g·ha⁻¹ Se nanoparticles application. With the exception of acetamiprid, the half-lives of thiamethoxam, abamectin, imidacloprid, and lambda-cyhalothrin were reduced from 2.4, 0.5, 1.2, 4.2 days without Se nanoparticles application to 1.4, 0.2, 0.9, 3.7 days with the addition of Se nanoparticles (2 g·ha⁻¹), respectively. The chronic dietary exposure risk probability (RQc) and the acute dietary exposure risk probability (RQa) of celery after Se nanoparticles application were within acceptable limits for consumption except for abamectin.