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Pesticide Biochemistry and Physiology Jun 2024Sitobion miscanthi is a destructive wheat pest responsible for significant wheat yield losses. Pirimicarb, one of the most important representatives of N,...
Sitobion miscanthi is a destructive wheat pest responsible for significant wheat yield losses. Pirimicarb, one of the most important representatives of N, N-dimethylcarbamate insecticides, is widely used to control wheat aphids. In present work, heterozygous S431F mutation of acetylcholinesterase 1 (AChE1) was identified and verified in three pirimicarb-resistant S. miscanthi populations (two field populations (HA and HS, >955.8-fold) and one lab-selected population (PirR, 486.1-fold)), which has not been reported in S. miscanthi yet. The molecular docking results revealed that AChE1 containing the S431F mutation of S. miscanthi (SmAChE1) showed higher free binding energy to three insecticides (pirimicarb, omethoate, and methomyl) than wild-type AChE1 of S. miscanthi (SmAChE1). Enzyme kinetic and inhibition experiments showed that the recombinant SmAChE1 was more insensitive to pirimicarb and omethoate than the recombinant SmAChE1. Furthermore, two overexpression P450 genes (CYP6K1 and CYP6A14) associated with pirimicarb resistance of S. miscanthi were verified by RNAi. These results suggested both target alteration and enhanced metabolism contributed to high pirimicarb resistance of S. miscanthi in the field and laboratory. These findings lay a foundation for further elucidating the mechanism of pirimicarb resistance in S. miscanthi, and have important implications for the resistance management of S. miscanthi control.
Topics: Acetylcholinesterase; Animals; Insecticide Resistance; Aphids; Insecticides; Carbamates; Cytochrome P-450 Enzyme System; Mutation; Pyrimidines; Molecular Docking Simulation; Triticum; Dimethoate
PubMed: 38879339
DOI: 10.1016/j.pestbp.2024.105957 -
Scientific Reports May 2024In this study, a sensitive and selective fluorescent chemosensor was developed for the determination of pirimicarb pesticide by adopting the surface molecular imprinting...
In this study, a sensitive and selective fluorescent chemosensor was developed for the determination of pirimicarb pesticide by adopting the surface molecular imprinting approach. The magnetic molecularly imprinted polymer (MIP) nanocomposite was prepared using pirimicarb as the template molecule, CuFeO nanoparticles, and graphene quantum dots as a fluorophore (MIP-CuFeO/GQDs). It was then characterized using X-ray diffraction (XRD) technique, Fourier transforms infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and transmission electron microscopy (TEM). The response surface methodology (RSM) was also employed to optimize and estimate the effective parameters of pirimicarb adsorption by this polymer. According to the experimental results, the average particle size and imprinting factor (IF) of this polymer are 53.61 nm and 2.48, respectively. Moreover, this polymer has an excellent ability to adsorb pirimicarb with a removal percentage of 99.92 at pH = 7.54, initial pirimicarb concentration = 10.17 mg/L, polymer dosage = 840 mg/L, and contact time = 6.15 min. The detection of pirimicarb was performed by fluorescence spectroscopy at a concentration range of 0-50 mg/L, and a sensitivity of 15.808 a.u/mg and a limit of detection of 1.79 mg/L were obtained. Real samples with RSD less than 2 were measured using this chemosensor. Besides, the proposed chemosensor demonstrated remarkable selectivity by checking some other insecticides with similar and different molecular structures to pirimicarb, such as diazinon, deltamethrin, and chlorpyrifos.
Topics: Pesticides; Carbamates; Quantum Dots; Molecularly Imprinted Polymers; Polymers; Spectrometry, Fluorescence; Graphite; Molecular Imprinting; Adsorption; Limit of Detection; Spectroscopy, Fourier Transform Infrared; Nanocomposites; Pyrimidines
PubMed: 38704412
DOI: 10.1038/s41598-024-60748-6 -
Journal of Pharmaceutical and... Aug 2024Pesticides play an important role in forensic toxicology and are usually classified as a single class of chemicals. Despite their commonly perceived unity, pesticides...
Development and validation of a multi-substance method for routine analysis of pesticides in post-mortem samples by Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry.
Pesticides play an important role in forensic toxicology and are usually classified as a single class of chemicals. Despite their commonly perceived unity, pesticides encompass a spectrum of compounds, including organophosphates, carbamates, pyrethroids or organochlorines, among others, each with varying degrees of toxicity. Pesticide analysis in post-mortem samples can be difficult due to the complexity of the samples and to the high toxicity of these compounds. The aim of this study was to develop and validate an easy to use, sensitive, and robust method, using ultra-performance liquid chromatography-tandem mass spectrometry to be incorporated in the routine flow for pesticide analysis in post-mortem blood samples. Described herein is a streamlined, expeditious, yet highly efficient method facilitating the screening, qualitative assessment, and quantitative confirmation of 15 pesticides, including acetamiprid, azinphos-ethyl, bendiocarb, carbofuran, chlorfenvinphos, dimethoate, imidaclopride, malathion, methiocarb, methomyl, parathion, pirimicarb, strychnine, tetrachlorvinphos, and thiacloprid in post-mortem blood, recognizing the pivotal role blood plays in forensic investigations. The developed method was linear from 10 to 200 ng/mL; limits of detection were between 1 and 10 ng/mL, depending on the compound; it was successfully evaluated a dilution ratio of 1-2, 5 and 10; and 8 substances showed maximum stability for the time interval studied. This UHPLC-MS/MS method is useful and a powerful tool in a toxicology lab because it is fast, simple, effective, and trustworthy. The results of this validation highlight the robustness of the analytical method, providing a valuable tool for the accurate and sensitive detection of pesticides in post-mortem blood. Poised for routine implementation, this method has already found success in suspected intoxication cases, promising to elevate the standards of forensic pesticide analysis.
Topics: Tandem Mass Spectrometry; Chromatography, High Pressure Liquid; Humans; Pesticides; Forensic Toxicology; Reproducibility of Results; Autopsy; Limit of Detection
PubMed: 38701535
DOI: 10.1016/j.jpba.2024.116176 -
Environmental Toxicology Apr 2024We performed multigenerational tests to clarify the chemical tolerance mechanisms of a nontarget aquatic organism, Daphnia magna. We continuously exposed D. magna to a...
We performed multigenerational tests to clarify the chemical tolerance mechanisms of a nontarget aquatic organism, Daphnia magna. We continuously exposed D. magna to a carbamate insecticide (pirimicarb) at lethal or sublethal concentrations (0, 3.8, 7.5, and 15 μg/L) for 15 generations (F0-F14). We then determined the 48 h-EC values and mRNA expression levels of acetylcholinesterase, glutathione S-transferase, and ATP (Adenosine triphosphate)-binding cassette transporter (ABCt) in neonates (<24 h old) from F0, F4, F9, and F14. To ascertain the effects of DNA methylation on pirimicarb sensitivity, we measured 5-methylcytosine levels (DNA methylation levels) in neonates of parents in the last generation (F14). In addition, we cultured groups exposed to 0 and 7.5 μg/L (the latter of which acquired chemical tolerance to pirimicarb) with or without 5-azacytidine (de-methylating agent) and determined methylation levels and 48 h-EC values in neonates (<24 h old) from the treated parents. The EC values (30.3-31.6 μg/L) in F14 of the 7.5 and 15 μg/L groups were approximately two times higher than that in the control (16.0 μg/L). A linear mixed model analysis showed that EC and ABCt mRNA levels were significantly increased with generational alterations; further analysis showed that the ABCt mRNA level was positively related to the EC . Therefore, ABCt may be associated with altered pirimicarb sensitivity. In addition, the EC value and DNA methylation levels in pirimicarb-tolerant clones decreased after exposure to 5-azacytidine, suggesting that DNA methylation contributes to chemical tolerance. These findings improved our knowledge regarding the acquisition of chemical tolerance in aquatic organisms.
Topics: Animals; Cladocera; Daphnia magna; Daphnia; Acetylcholinesterase; DNA Methylation; ATP-Binding Cassette Transporters; Water Pollutants, Chemical; Aquatic Organisms; Azacitidine; RNA, Messenger; Carbamates; Pyrimidines
PubMed: 38073494
DOI: 10.1002/tox.24077 -
Insects Sep 2023The invasive apricot aphid ( Matsumura) is an important pest of apricot trees ( L.). In the presented study, laboratory bioassays using treated leaf disks of apricot...
The invasive apricot aphid ( Matsumura) is an important pest of apricot trees ( L.). In the presented study, laboratory bioassays using treated leaf disks of apricot were conducted to test the efficacy of twelve insecticides according to the maximum field dose. Additionally, dose-response curves were established for selected insecticides, and the effects on colony development were evaluated. Furthermore, a field trial was conducted to investigate the effectiveness of commonly used insecticides in apricot cultivation. The dose-response curves showed LC values ranging from 0.08 mg/L for flupyradifurone, 0.15 mg/L for acetamiprid, 0.70 mg/L for etofenprox, 1.89 mg/L for sulfoxaflor, 2.64 mg/L for pirimicarb, 3.97 mg/L for deltamethrin, up to 6.79 mg/L for tau-fluvalinate. These aforementioned insecticides resulted in mortality rates ranging from 95 to 100% at the field dose. Azadirachtin, flonicamid, and pyrethrins showed mortality rates of 27 to 45%. Spirotetramat reduced the colony development and decreased the number of infested shoots by 86%. Spinosad, which is not recommended against aphids, showed minimal impact; reducing the number of exuviae in nymphs in the colony development bioassay. It can be concluded that the majority of the tested insecticides are effective against .
PubMed: 37754715
DOI: 10.3390/insects14090746 -
Foods (Basel, Switzerland) Aug 2023In this study, a new approach to pesticide permeation through the apple peel into the pulp is discussed. The tested compounds can be classified, based on mode of action,...
In this study, a new approach to pesticide permeation through the apple peel into the pulp is discussed. The tested compounds can be classified, based on mode of action, as systemic (boscalid, cyprodinil, pirimicarb, propiconazole and tebuconazole) or contact (captan, cypermethrin and fludioxonil) pesticides. The barrier effect was assessed using a Franz flow-type vertical diffusion cell system. A residue analysis was performed using a modified quick, easy, cheap, efficient, rugged and safe (QuEChERS) extraction method coupled to gas chromatography with tandem mass spectrometry (GC-MS/MS). The limits of detection (LODs) ranged between 2.6 µg kg (pirimicarb) and 17 µg kg (captan), with the coefficient of variability (CV) lower than 6%, while recoveries ranged from 85% (boscalid) to 112% (captan) at 0.1 and 1 mg kg spiked levels. The highest peel penetration was observed for pirimicarb, captan and cyprodinil, with cumulative permeations of 90, 19 and 17 µg cm, respectively. The total absorption was in the range from 0.32% (tebuconazole) to 32% (pirimicarb). Only cypermethrin was not quantitatively detected in the pulp, and its use can be recommended in crop protection techniques. The obtained results indicate that molecular weight, octanol-water partition coefficient and water solubility are important parameters determining the process of pesticide absorption.
PubMed: 37685153
DOI: 10.3390/foods12173220 -
Journal of Environmental Management Nov 2023An amount of works has reported the effect of wastewater matrix composition on pollutants removal by different AOPs. The biggest challenge is that each wastewater source...
An amount of works has reported the effect of wastewater matrix composition on pollutants removal by different AOPs. The biggest challenge is that each wastewater source has a challenging composition (organic and inorganic compounds, pollutants, etc.) and not only the concentration of all these species but also the interaction between them may affect the effectiveness of the studied process. This work has been carried out to evaluate the photo-degradation kinetics of six different pesticides (flutriafol, imidacloprid, myclobutanil, pirimicarb, thiamethoxam and triadimenol) by solar photo-Fenton (SPF) process at acidic pH. First, oxidant concentration (HO) was optimized with an actual WWTP effluent. Then, the process was validated with two different secondary and tertiary WWTP effluents, in which main intermediate transformation by-products were identified. Finally, the effect of the inorganic water matrix components (bicarbonate, chloride, sulphate, nitrate and phosphate) was evaluated by a multivariate analysis. Once HO has been optimized at 30 mg L, the photo-degradation efficiency of pesticides in real wastewater samples was compared. DOC content of both secondary and tertiary WWTP effluents was dropped by 67%. The identification of the main intermediate transformation by-products (such as 1H-1,2,4-triazole, desmethyl-formamido pirimicarb, thiamethoxam urea, chloronicotinic acid and imidacloprid urea) was reviewed. Following, the multivariate analysis on pesticides photo-degradation, generally, predicted four significant effects in common for the studied pesticides: a positive effect (interaction bicarbonate/nitrate) and three negative ones (chloride, phosphate and the interaction chloride/sulphate); among others. In addition, optimum values of inorganic ion concentrations, to obtain an optimum desirability on studied pesticides removal by SPF at acidic pH, were also evaluated.
Topics: Wastewater; Pesticides; Hydrogen Peroxide; Iron; Thiamethoxam; Bicarbonates; Chlorides; Nitrates; Environmental Pollutants; Water Pollutants, Chemical; Oxidation-Reduction
PubMed: 37536137
DOI: 10.1016/j.jenvman.2023.118699 -
Highly Active Single-Atom Nanozymes with High-Loading Iridium for Sensitive Detection of Pesticides.Analytical Chemistry Aug 2023Single-atom nanozymes (SAzymes) are novel mimic-enzyme materials with atomically doped active sites. They play a pivotal role in the field of nanozymes because of their...
Single-atom nanozymes (SAzymes) are novel mimic-enzyme materials with atomically doped active sites. They play a pivotal role in the field of nanozymes because of their excellent catalytic activities, high utilization efficiency of the metal atoms, and simple model of active sites. Herein, the peroxidase (POD)-like SAzymes with high-loading iridium (Ir) (5.31%) on graphene oxide (GO) nanosheets [Ir(III)/GO] were prepared through a coordination reaction between the Ir(III) complex and the oxygen-containing groups in GO. The preparation strategy avoids nitrogen doping and pyrolysis procedures which are the usually used strategies to improve the GO-based enzyme mimic activity. Ascribed to the highly active Ir atoms, Ir(III)/GO SAzymes demonstrate outstanding POD-like activity without the oxidase-like activity. In advantage of the excellent POD-like activity, a simple and sensitive colorimetric pesticide detection platform is established. The developed sensing platform offers an excellent "switch-on" pirimicarb (PIB) detection in the linear range of 10-300 nM with a limit of detection (LOD) of 2.81 nM. Moreover, the detection platform was fabricated into a portable test kit, which is composed of a test swab and sample processing tube. In the aid of a color-reading APP, the test kit can detect PIB with the LOD of 3.31 nM. It is astonishing to get this excellent detection sensitivity just using the simple colorimetric strategy. This work not only provides a novel strategy to synthesize Ir-based SAzymes but also exhibits the super capability of Ir(III)/GO in the biosensing field.
Topics: Iridium; Carbamates; Colorimetry; Pesticides
PubMed: 37530640
DOI: 10.1021/acs.analchem.3c01569 -
Pest Management Science May 2024Failures in controlling Myzus persicae by pyrethroids and carbamates have been observed in Czechia since 2018. Eleven populations collected from Czech oilseed rape...
BACKGROUND
Failures in controlling Myzus persicae by pyrethroids and carbamates have been observed in Czechia since 2018. Eleven populations collected from Czech oilseed rape fields during 2018-2021 were tested for susceptibility to 11 insecticides. The presence of a single nucleotide polymorphism (SNP) leading to knockdown resistance in M. persicae populations was screened using allelic discriminating quantitative real-time polymerase chain reaction (qPCR). The presence of mutations related with the resistance of M. persicae to pyrethroids and carbamates was detected by sequencing paratype voltage-gated sodium channel and acetylcholinesterase 2 genes, respectively.
RESULTS
Resistance to alpha-cypermethrin and pirimicarb was detected in most of the tested populations. The L1014F mutation was detected in 44.5% of M. persicae individuals surviving the field-recommended dose of alpha-cypermethrin. Sequencing of partial para gene for paratype voltage-gated sodium channel detected five different SNPs leading to four amino acid substitutions (kdr L1014F; s-kdr M918L; s-kdr M918T; and L932F). No pyrethroid-sensitive genotype was detected. The S431F amino acid substitution conferring resistance to carbamates was detected in 11 of 20 individuals with different pyrethroid-resistance genotypes.
CONCLUSION
Resistance of M. persicae to both pyrethroids and carbamates was detected in nine of 11 populations. High resistance of M. persicae was correlated with mutations of the sodium channel. Sulfoxaflor, flonicamid, and spirotetramat are proposed as effective compounds to control pyrethroid- and carbamate-resistant populations of M. persicae. © 2023 Society of Chemical Industry.
Topics: Animals; Humans; Aphids; Acetylcholinesterase; Czech Republic; Pyrethrins; Insecticides; Mutation; Carbamates; Voltage-Gated Sodium Channels; Brassica napus; Insecticide Resistance
PubMed: 37402271
DOI: 10.1002/ps.7646 -
Journal of Chromatography. B,... Jun 2023Carbamate pesticides are extensively used in agriculture for their inhibition to acetylcholinesterase and damages to the insects' neural systems. Because of their...
A retrospective screening method for carbamate toxicant exposure based on butyrylcholinesterase adducts in human plasma with ultra-high performance liquid chromatography-tandem mass spectrometry.
Carbamate pesticides are extensively used in agriculture for their inhibition to acetylcholinesterase and damages to the insects' neural systems. Because of their toxicity, human poisoning incidents caused by carbamate pesticide exposure have occurred from time to time. What's more, some lethally toxic carbamate toxicants known as carbamate nerve agents (CMNAs) have been supplemented in Schedule 1 of the Annex on Chemicals in the Chemical Weapons Convention (CWC) by Organisation of the Prohibition of Chemical Weapons (OPCW) from 2020. And some other carbamates, like physostigmine, have been used in clinical treatment as anticholinergic drugs and their misuse may also cause damages to the body. Similar to organophosphorus toxicants, carbamate toxicants would react with butyrylcholinesterase (BChE) in plasma when entering the human body, resulting in the BChE adducts, based on which the exposure of carbamate toxicants could be detected retrospectively. In this study, methylcarbamyl nonapeptide and dimethylcarbamyl nonapeptide from pepsin digestion of BChE adducts were identified with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in product ion scan mode. Carbofuran was chosen as the target to establish the detection method of carbamate toxicant exposure based on methylcarbamyl nonapeptide digested from methylcarbamyl BChE. Procainamide-gel affinity purification, pepsin digestion and UHPLC-MS/MS analysis in multiple reaction monitoring (MRM) mode were applied. Under the optimized conditions of sample preparation and UHPLC-MS/MS MRM analysis, the limits of detection (LODs) reached 10.0 ng/mL of plasma exposed to carbofuran with satisfactory specificity. The quantitation approach was established with d-carbofuran-exposed plasma as the internal standard (IS) and the linearity range was 30.0-1.00 × 10 nmol/L (R >0.998) with the accuracy of 95.6%-107% and precision of ≤9% relative standard deviation (RSD). The applicability was also evaluated by N,N-dimethyl-carbamates with the LODs of 30.0 nmol/L for pirimicarb-exposed plasma based on dimethylcarbamyl nonapeptide. Because most of carbamate toxicants has methylcarbamyl or dimethylcarbamyl groups, this approach could be applied on the retrospective screening of carbamate toxicant exposure including CMNAs, carbamate pesticides or carbamate drugs. This study could provide an effective means in the fields of CWC verification, toxicological mechanism investigation and down-selection of potential treatment options.
Topics: Humans; Butyrylcholinesterase; Chromatography, High Pressure Liquid; Tandem Mass Spectrometry; Retrospective Studies; Carbofuran; Acetylcholinesterase; Pepsin A; Nerve Agents; Pesticides
PubMed: 37285767
DOI: 10.1016/j.jchromb.2023.123775