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1.
Food Chem ; 339: 127985, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32920305

RESUMO

There is limited research focusing on the effects of human gut microbiota on the oral bioaccessibility and intestinal absorption of pesticide residues in food. In the present study, we use a modified setup of the Simulator of the Human Intestinal Microbial Ecosystem for the determination of pesticide residue bioaccessibility in Chaenomeles speciosa, and a Caco-2 cell model of human intestinal absorption. Results showed that gut microbiota played a dual role based their effects on contaminant release and metabolism in the bioaccessibility assay, and Lactobacillus plantarum was one of key bacterial species in the gut microbiota that influenced pesticide stability significantly. The addition of L. plantarum to the system reduced the relative amounts (by 11.40-86.51%) of six pesticides. The interaction between the food matrix and human gut microbiota led to different absorption rates, and the barrier effects increased with an increase in incubation time.


Assuntos
Microbioma Gastrointestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Praguicidas/farmacologia , Rosaceae/química , Bactérias/metabolismo , Células CACO-2 , Humanos , Mucosa Intestinal/citologia , Mucosa Intestinal/microbiologia , Lactobacillus plantarum/efeitos dos fármacos , Lactobacillus plantarum/isolamento & purificação , Neonicotinoides/metabolismo , Neonicotinoides/farmacologia , Nitrocompostos/metabolismo , Nitrocompostos/farmacologia , Compostos Organotiofosforados/metabolismo , Compostos Organotiofosforados/farmacologia , Praguicidas/química , Praguicidas/metabolismo , Rosaceae/metabolismo , Tiametoxam/metabolismo , Tiametoxam/farmacologia
2.
Ecotoxicol Environ Saf ; 209: 111814, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33360286

RESUMO

Thiamethoxam (THM) and imidacloprid (IMI), are environmentally persistent neonicotinoid insecticides which have become increasingly favored in the past decade due to their specificity as insect neurotoxicants. However, neonicotinoids have been implicated as a potential contributing factor in Colony Collapse Disorder (CCD) which affects produce production on a global scale. The present study characterizes the bioremediation potential of six bacterial species: Pseudomonas fluorescens, Pseudomonas putida, Pseudomonas aeruginosa, Alcaligenes faecalis, Escherichia coli, and Streptococcus lactis. In Phase I, we evaluated the utilization of IMI or THM as the sole carbon or nitrogen source by P. fluorescens, P. putida, and P. aeruginosa. All three species were better able to utilize THM over IMI as their sole carbon or nitrogen source. Thus, further studies proceeded with THM only. In Phase II, we assessed the kinetics of THM removal from aqueous media by the six species. Significant (p < 0.0001) reductions in 70 mg/L THM concentration were observed for P. fluorescens (67%), P. putida (65%), P. aeruginosa (52%), and A. faecalis (39%) over the 24-day study period, and for E. coli (60%) and S. lactis (12%) over the 14-day study period. The THM removal by all species followed a first-order kinetic reaction. HPLC chromatograms of P. fluorescens, P. putida, and E. coli cultures revealed that as the area of the THM peak decreased over time, the area of an unidentified metabolite peak increased. In Phase III, we examined the effect of temperature on the transformation capacity of the bacterial species which was observed at 2 â„ƒ, 22 â„ƒ, and 30 â„ƒ. Maximal THM removal occurred at 30 °C for all bacterial species assessed. Identification of the metabolite is currently underway. If the metabolite is found to be less hazardous than THM, further testing will follow to evaluate the use of this bioremediation technique in the field.


Assuntos
Biodegradação Ambiental , Inseticidas/metabolismo , Neonicotinoides/metabolismo , Nitrocompostos/metabolismo , Tiametoxam/metabolismo , Animais , Escherichia coli/metabolismo , Inseticidas/análise , Inseticidas/toxicidade , Cinética , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Oxazinas , Pseudomonas putida/metabolismo , Tiametoxam/toxicidade
3.
Environ Pollut ; 257: 113499, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31706771

RESUMO

Production of chrysanthemum (Dendranthema grandiflora) in greenhouses often requires intensive pesticide use, which raises serious concerns over food safety and human health. This study investigated uptake, translocation and residue dissipation of typical fungicides (metalaxyl-M and fludioxonil) and insecticides (cyantraniliprole and thiamethoxam) in greenhouse chrysanthemum when applied in soils. Chrysanthemum plants could absorb these pesticides from soils via roots to various degrees, and bioconcentration factors (BCFLS) were positively correlated with lipophilicity (log Kow) of pesticides. Highly lipophilic fludioxonil (log Kow = 4.12) had the greatest BCFLS (2.96 ±â€¯0.41 g g-1), whereas hydrophilic thiamethoxam (log Kow = -0.13) had the lowest (0.09 ±â€¯0.03 g g-1). Translocation factors (TF) from roots to shoots followed the order of TFleaf > TFstem > TFflower. Metalaxyl-M and cyantraniliprole with medium lipophilicity (log Kow of 1.71 and 2.02, respectively) and hydrophilic thiamethoxam showed relatively strong translocation potentials with TF values in the range of 0.29-0.81, 0.36-2.74 and 0.30-1.03, respectively. Dissipation kinetics in chrysanthemum flowers followed the first-order with a half-life of 21.7, 5.5, 10.0 or 8.2 days for metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam, respectively. Final residues of these four pesticides, including clothianidin (a primary toxic metabolite of thiamethoxam), in all chrysanthemum flower samples were below the maximum residue limit (MRL) values 21 days after two soil applications each at the recommended dose (i.e., 3.2, 2.1, 4.3 and 4.3 kg ha-1, respectively). However, when doubling the recommended dose, the metabolite clothianidin remained at concentrations greater than the MRL, despite that thiamethoxam concentration was lower than the MRL value. This study provided valuable insights on the uptake and residues of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam (including its metabolite clothianidin) in greenhouse chrysanthemum production, and could help better assess food safety risks of chrysanthemum contamination by parent pesticides and their metabolites.


Assuntos
Chrysanthemum/metabolismo , Praguicidas/metabolismo , Alanina/análogos & derivados , Alanina/metabolismo , Dioxóis/metabolismo , Fungicidas Industriais/análise , Guanidinas , Humanos , Inseticidas/análise , Neonicotinoides , Resíduos de Praguicidas/análise , Pirazóis/metabolismo , Pirróis/metabolismo , Solo/química , Poluentes do Solo/análise , Tiametoxam/metabolismo , Tiazóis , ortoaminobenzoatos/metabolismo
4.
Insect Biochem Mol Biol ; 118: 103285, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31760137

RESUMO

Insecticides are a key tool in the management of many insect pests of agriculture, including soybean aphids. The selection imposed by insecticide use has often lead to the evolution of resistance by the target pest through enhanced detoxification mechanisms. We hypothesised that exposure of insecticide-susceptible aphids to sublethal doses of insecticides would result in the up-regulation of genes involved in detoxification of insecticides, revealing the genes upon which selection might act in the field. We used the soybean aphid biotype 1 reference genome, version 6.0 as a reference to analyze RNA-Seq data. We identified multiple genes with potential detoxification roles that were up-regulated 12 h after sublethal exposure to esfenvalerate or thiamethoxam. However, these genes were part of a dramatic burst of differential gene expression in which thousands of genes were up- or down-regulated, rather than a defined response to insecticides. Interestingly, the transcriptional burst observed at 12 h s declined dramatically by 24-hrs post-exposure, suggesting a general stress response that may become fine-tuned over time.


Assuntos
Afídeos/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Genes de Insetos/efeitos dos fármacos , Inseticidas/metabolismo , Nitrilos/metabolismo , Piretrinas/metabolismo , Tiametoxam/metabolismo , Animais , Afídeos/genética , Regulação para Baixo/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
5.
J Agric Food Chem ; 67(43): 11848-11859, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31600442

RESUMO

To decrease the application dose of thiamethoxam (TMX) to control the pepper whitefly (Bemisia tabaci Q), the deposition, dissipation, metabolism, and field efficacy of TMX were investigated in a pepper (Capsicum annuum var. grossum)-planted ecosystem using eight types of nozzles at six concentrations (56.25, 41.25, 26.25, 21.0, 15.75, and 10.5 g a.i./hm2). The initial deposition amount of TMX in the pepper plant first increased and then decreased with increasing application dose. The optimum spray conditions of TMX were found to be a droplet size of 200 µm volume median diameter and a spray volume of 350 L/hm2. Moreover, three metabolites, TMX-dm, clothianidin (CLO), and C5H8O2N3SCl, were detected in the pepper-planted system. The dissipation rate of TMX in the pepper-field ecosystem was leaves > stems > fruits > roots > soils. The results revealed the deposition and fate of TMX in the pepper-field ecosystem, and the application dose could be reduced by 20% based on the minimum recommended dose for controlling pepper whitefly.


Assuntos
Capsicum/química , Inseticidas/química , Tiametoxam/química , Animais , Capsicum/metabolismo , Ecossistema , Frutas/química , Frutas/metabolismo , Inseticidas/metabolismo , Cinética , Folhas de Planta/química , Folhas de Planta/metabolismo , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Caules de Planta/química , Caules de Planta/metabolismo , Solo/química , Tiametoxam/metabolismo
6.
Ecotoxicol Environ Saf ; 183: 109488, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31376804

RESUMO

The extensive application of pesticides in agricultural activities has raised increasing concerns on crop contamination by pesticide residues. Vegetables seem more susceptible to pesticide contamination given the high-intensive application of pesticides during their entire growth, while information about transfer and cell diffusion characteristics of pesticides in vegetables is currently insufficient. Here, we investigated the uptake, translocation and subcellular distribution behaviors of four commonly used pesticides in Chinese cabbage (Brassica rapa var. chinensis) under laboratory hydroponic conditions. Root uptake of pesticides followed the order of fenbuconazole > avermectin > thiamethoxam > spirotetramat. Thiamethoxam was more readily to be translocated from vegetable root to shoot, while spirotetramat, fenbuconazole and avermectin preferentially accumulated in vegetable root. Cell soluble components were the dominant storage compartment for thiamethoxam. The majority of spirotetramat, fenbuconazole and avermectin were partitioned into the cell walls. Hopefully, results of this study would extend the current knowledge of pesticide bioconcentration behavior in food-crops and assist in properly evaluating the threats of pesticide residues to human health via food chain.


Assuntos
Brassica rapa/metabolismo , Praguicidas/metabolismo , Compostos Aza/metabolismo , Transporte Biológico , Humanos , Hidroponia , Ivermectina/análogos & derivados , Ivermectina/metabolismo , Nitrilos/metabolismo , Raízes de Plantas/metabolismo , Compostos de Espiro/metabolismo , Tiametoxam/metabolismo , Triazóis/metabolismo
7.
J Agric Food Chem ; 67(26): 7538-7546, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31180663

RESUMO

Thiamethoxam (TMX) has already been proven to have a physiological effect in plant tissue or cell expect for the insecticidal activity. In our previous study, TMX was verified to be metabolized by tea cells in either a suspension culture or tea plant into several metabolites. Here, tea cell suspension cultures were treated for 45 days to investigate the metabolite effects in both the tea cells and the culture supernatants by nontargeted metabolomics. Using multivariate analysis (PCA and OPLS-DA), all treatment and control groups could be clearly separated. Inside the cells, 113 metabolites were found to be up-regulated while 122 were down-regulated, when compared with untreated cells. In the culture supernatant, there were 128 up-regulated and 35 down-regulated metabolites, compared to untreated cultures. KEGG searches revealed that the alanine, aspartate, and glutamate metabolic pathways were strongly affected by TMX metabolism within the tea cell. Molecular docking models showed that (i) 4-aminobutyrate aminotransferase may be related to the formation of 2-chloro-thiazole-5-carboxylic acid and (ii) 3'(2'),5'-bisphosphate nucleotidase may be able to interact with TMX. This study can help us to understand the interaction mechanism of pesticides with plant cells.


Assuntos
Camellia sinensis/química , Camellia sinensis/metabolismo , Inseticidas/metabolismo , Tiametoxam/metabolismo , Células Cultivadas , Inseticidas/química , Redes e Vias Metabólicas , Metabolômica , Simulação de Acoplamento Molecular , Tiametoxam/química
8.
Ecotoxicology ; 28(2): 222-228, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30666494

RESUMO

Neonicotinoid seed treatments are extensively used to systemically protect corn from invertebrate herbivory. Interseeding cover crops can promote beneficial insect communities and their ecosystem services such as predation on pests, and this practice is gaining interest from farmers. In this study, cereal rye (Secale cereale) and hairy vetch (Vicia villosa) were planted between rows of early vegetative corn that had been seed-treated with thiamethoxam. Thiamethoxam and its insecticidal metabolite, clothianidin were quantified in cover crop leaves throughout the growing season. Thiamethoxam was present in cereal rye at concentrations ranging from 0 to 0.33 ± 0.09 ng/g of leaf tissue and was detected on six out of seven collection dates. Cereal rye leaves contained clothianidin at concentrations from 1.05 ± 0.22 to 2.61 ± 0.24 ng/g and was present on all sampling dates. Both thiamethoxam and clothianidin were detected in hairy vetch on all sampling dates at rates ranging from 0.10 ± 0.05 to 0.51 ± 0.11 ng/g and 0.56 ± 0.15 to 9.73 ± 5.04 ng/g of leaf tissue, respectively. Clothianidin was measured at a higher concentration than its precursor, thiamethoxam, in both plant species on every sampling date. Neonicotinoids entering interseeded cover crops from adjacent treated plants is a newly discovered route of exposure and potential hazard for non-target beneficial invertebrates. Future research efforts should examine the effects of systemic insecticides on biological communities in agroecosystems whose goal is to diversify plant communities using methods such as cover cropping.


Assuntos
Guanidinas/metabolismo , Inseticidas/metabolismo , Neonicotinoides/metabolismo , Secale/química , Tiametoxam/metabolismo , Tiazóis/metabolismo , Vicia/química , Animais , Ecossistema , Insetos , Controle Biológico de Vetores , Folhas de Planta/química , Sementes/química , Zea mays/química
9.
Pest Manag Sci ; 75(5): 1339-1345, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30367747

RESUMO

BACKGROUND: Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is an important pest of citrus worldwide because it transmits the bacteria causing huanglongbing (HLB). We investigated the effects and persistence of two soil application rates of thiamethoxam on ACP populations in two flushing seasons in the field. Thiamethoxam and clothianidin residues in the fruit were detected to evaluate food safety. RESULTS: Soil application of 50% thiamethoxam water-dispersible granules at concentrations of 4 and 10 g tree-1 significantly decreased ACP populations, and there was a positive correlation between control efficacy and the persistence of thiamethoxam and clothianidin in leaves, providing longer-term protection for up to 90 days in the fall compared with 60 days in the spring. Higher thiamethoxam and clothianidin amounts were observed in new leaves than in old leaves. Thiamethoxam and clothianidin residues at a high rate in fruit were 0.012 and 0.010 mg kg-1 at harvest, respectively, and neither insecticides was detectable at low rates. CONCLUSIONS: These results demonstrate that soil-applied thiamethoxam plays a role in defending ACP, and provides an extended period of control efficacy. This knowledge could provide a reference for the control of ACP by soil application of thiamethoxam to reduce HLB spread. © 2018 Society of Chemical Industry.


Assuntos
Citrus/metabolismo , Hemípteros , Estações do Ano , Solo/química , Tiametoxam/metabolismo , Animais , Transporte Biológico , Citrus/microbiologia , Inocuidade dos Alimentos , Guanidinas/metabolismo , Hemípteros/fisiologia , Resistência a Inseticidas , Limite de Detecção , Modelos Lineares , Neonicotinoides/metabolismo , Resíduos de Praguicidas/metabolismo , Doenças das Plantas/microbiologia , Folhas de Planta/metabolismo , Tiazóis/metabolismo
10.
Chemosphere ; 217: 150-157, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30419375

RESUMO

The neurotoxicity of dinotefuran, thiamethoxam and imidacloprid against Chinese lizards (Eremias argus) were evaluated in acute oral exposure and 28d subchronic exposure. Dinotefuran was not easily metabolized and showed strong persistence in the lizard brain. Thiamethoxam and imidacloprid were rapidly absorbed and excreted in lizards, and were not easily enriched in the lizard brain. Dinotefuran and thiamethoxam could directly increase the concentrations of acetylcholine in the brain and blood by up-regulating the expression of the ach gene, which in turn enhanced the binding of acetylcholine and acetylcholinesterase receptors, eventually causing the release of dopamine. The effect of dinotefuran was more pronounced than thiamethoxam. Clothianidin was a major metabolite of thiamethoxam in the brain and aggravated the neurotoxic effects of thiamethoxam. Imidacloprid desnitro olefin was the only metabolite of imidacloprid that enriched in the brain. The protonation effect of imidacloprid desnitro olefin was stronger than that of the parent imidacloprid, which increased its binding ability to lizard acetylcholinesterase receptors. Competitive inhibition of imidacloprid desnitro olefin and acetylcholine led to the down-regulation of ach gene expression. Although neonicotinoids caused the opening of ligand-gated ion channel through the activation of acetylcholinesterase receptors, the body would alleviate these effects by the inhibition of voltage-dependent channel activity for compensatory mechanisms. This study provided a new perspective on the neotoxic effects of neonicotinoids.


Assuntos
Guanidinas/toxicidade , Lagartos/metabolismo , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Tiametoxam/toxicidade , Acetilcolina/genética , Acetilcolina/metabolismo , Animais , Guanidinas/metabolismo , Inseticidas/toxicidade , Neonicotinoides/metabolismo , Neonicotinoides/farmacologia , Síndromes Neurotóxicas/etiologia , Tiametoxam/metabolismo , Tiazóis/metabolismo
11.
Sci Rep ; 8(1): 15242, 2018 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-30323350

RESUMO

Few studies focused on the residue of thiamethoxam and its metabolite clothianidin on strawberry where it is widely used, despite this is essential to assess the potential food risk of thiamethoxam and its main metabolite clothianidin. In this study, the dissipation of thiamethoxam and its metabolite clothianidin during strawberry growth and jam-making process were assessed. The strawberry was sprayed with thiamethoxam based on the field application to investigate the dissipation of thiamethoxam as well as clothianidin formation. The half-life of thiamethoxam in strawberry was 9.0 days and the concentration of clothianidin in strawberry gradually increased from 0.55 to 11 µg/kg within 30 days. In addition, the amount of thiamethoxam decreased by 51.7% and clothianidin decreased by 40.2% during the homogenization process. The processing factor values of whole processing all less than 1 except simmering. This results from this study will not only help to understand the dissipation kinetics of thiamethoxam and clothianidin in the strawberry, but also facilitate to make more accurate risk assessments of them during strawberry jam making process.


Assuntos
Fragaria/metabolismo , Guanidinas/metabolismo , Inseticidas/metabolismo , Neonicotinoides/metabolismo , Tiametoxam/metabolismo , Tiazóis/metabolismo , Fragaria/química , Fragaria/crescimento & desenvolvimento , Guanidinas/química , Humanos , Inseticidas/química , Neonicotinoides/química , Resíduos de Praguicidas/química , Resíduos de Praguicidas/metabolismo , Tiametoxam/química , Tiazóis/química
12.
Chemphyschem ; 19(22): 3069-3083, 2018 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-30216679

RESUMO

The structural features and molecular-interaction properties of thiamethoxam (THA) and clothianidin (CLO) - two neonicotinoids - have been investigated through a combined approach based on a wide range of molecular modeling methods and X-ray-structure observations. Despite their close chemical structures, significant differences are emphasized by QM (DFT), docking, molecular dynamics, and QM/QM' calculations. Thus, for the first time, their propensity to interact through chalcogen-bond interactions is highlighted. The influence of the surroundings on this behavior is pointed out: in CLO, an intramolecular S⋅⋅⋅N chalcogen bond is shown to stabilize the structure in the solid state whereas the interaction leads to the preferred conformations in the isolated and continuum solvent models for both compounds. Interestingly, this interaction potential appears to be used for their binding to Ac-AChBP through intermolecular S⋅⋅⋅O chalcogen bonds with the hydroxyl group of Tyr195. The use of a suitable level of theory to describe properly these interactions is underlined, the classical methods being unsuited to highlight these interactions. The contribution of halogen bonding through the chlorine atom of the chlorothiazole ring in the binding of the two compounds is also underlined, both in the solid state and in the Ac-AChBP surroundings. However, the accommodation of the two insecticides in the binding site leads to the fact that a halogen-bond contribution is pointed out only for CLO.


Assuntos
Guanidinas/química , Inseticidas/química , Neonicotinoides/química , Receptores Nicotínicos/química , Tiametoxam/química , Tiazóis/química , Animais , Aplysia/metabolismo , Sítios de Ligação , Guanidinas/metabolismo , Inseticidas/metabolismo , Conformação Molecular , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Neonicotinoides/metabolismo , Teoria Quântica , Receptores Nicotínicos/metabolismo , Eletricidade Estática , Termodinâmica , Tiametoxam/metabolismo , Tiazóis/metabolismo
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