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1.
Anal Chim Acta ; 1183: 338938, 2021 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-34627522

RESUMO

The spiropyran (SP) compound is a typical photochromic compound. Its merocyanine configuration (MC) can accept energy and be excited by visible light, while the closed-loop configuration cannot. In this work, the SP was wrapped in ß-cyclodextrin (ß-CD-SP) firstly. When it was competitively replaced by thiamethoxam and dissociated out of ß-CD, it would be converted to MC, which could be excited by visible light around 550 nm to produce red fluorescence. Here, CsPbBr3 was selected as the energy donor based on the principle of fluorescence resonance energy transfer (FRET). In order to connect with ß-CD-SP and improve its stability, CsPbBr3 was wrapped in mesoporous silica, and then the second wrapping was performed to block those mesopores and the amination reaction was carried out (NH2-SiO2@CsPbBr3). Subsequently, NH2-SiO2@CsPbBr3 with green fluorescence (506 nm) was used as the internal standard and excitation light source for MC, and the red fluorescence of MC was used as the response signal to construct a ratiometric fluorescence sensor. When thiamethoxam was added and excited by 365 nm ultraviolet light, the energy would be transferred from NH2-SiO2@CsPbBr3 (506 nm) that emitted green fluorescence to MC, which emitted red fluorescence. So, the fluorescence color changed from green to yellow to red with the addition of the thiamethoxam. This sensor was employed to detect thiamethoxam in soil and yam.


Assuntos
Transferência Ressonante de Energia de Fluorescência , Dióxido de Silício , Benzopiranos , Indóis , Nitrocompostos , Tiametoxam
2.
Environ Monit Assess ; 193(10): 665, 2021 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-34545435

RESUMO

Aedes aegypti is an important vector of dengue fever, dengue hemorrhagic fever and yellow fever, chikungunya, and Zika virus. The objective was to evaluate the resistance of A. aegypti exposed to insecticides with different action modes (deltamethrin, imidacloprid, and fipronil) under intense selection pressure for 10 generations in laboratory. Bioassays were conducted according to World Health Organization. Biochemical assay performed after selection with deltamethrin (Delta-SEL), fipronil (Fipro-SEL), and imidacloprid (Imida-SEL) from G1 to G10 was used for the assessment of detoxification enzymes (esterase (EST), acetylcholinesterase (AChE), glutathione S-transferases (GST), and acid and alkaline phosphatases (ACP and ALP)). The Fipro-SEL (G10) had high resistance (77-fold), whereas Delta-SEL and Imida-SEL populations presented very high resistance with 118 and 372-fold, respectively, in comparison with unselected (UNSEL). The levels of EST, AChE, GST, ACP, and ALP enzymes amplified on application from G1 to G10. The enzymes contributing in resistance development of insecticides were as follows: GST (20.7 µmol/min/mg of protein) in Delta-SEL (G10), while AChE 9.71 µmol/min/mg of protein in Imida-SEL (G10) and the peak ACP and ALP enzyme activities 13.32 and 12.93 µmol/min/mg of protein, respectively, in Fipro-SEL (G10). The results showed that detoxification enzymes trigger insecticide resistance in A. aegypti and their suppression may aid in the resistance breakage.


Assuntos
Aedes , Inseticidas , Piretrinas , Infecção por Zika virus , Zika virus , Acetilcolinesterase , Animais , Monitoramento Ambiental , Inseticidas/toxicidade , Larva , Mosquitos Vetores , Neonicotinoides , Nitrilas , Nitrocompostos , Pirazóis , Piretrinas/toxicidade
3.
Ecotoxicol Environ Saf ; 225: 112719, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34478976

RESUMO

Dissipation of imidacloprid (IMI) and its metabolites (urea, olefin, 5-hydroxy, guanidine, 6-chloronicotinic acid) in Chinese prickly ash (CPA) was investigated using QuEChERS combined with UPLC-MS/MS. Good linearity (r2 ≥0.9963), accuracy (recoveries of 71.8-104.3%), precision (relative standard deviations of 0.9-9.4%), and sensitivity (limit of quantification ≤0.05 mg kg-1) were obtained. After application of IMI at dosage of 467 mg a.i. L-1 for three times with interval of 7 d, the dissipation dynamics of IMI in CPA followed first-order kinetics, with half-life of 6.48-7.29 d. IMI was the main compound in CPA, followed by urea and guanidine with small amounts of olefin, 5-hydroxy, and 6-chloronicotinic acid. The terminal residues of total IMI and its metabolites at PHI of 14-21 d were 0.16-7.80 mg kg-1 in fresh CPA and 0.41-10.44 mg kg-1 in dried CPA, with the median processing factor of 3.62. Risk assessment showed the acute (RQa) and chronic dietary risk quotients (RQc) of IMI in CPA were 0.020-0.083% and 0.052-0.334%, respectively. Based on the dietary structures of different genders and ages of Chinese people, the whole dietary risk assessment indicated that RQc was less than 100% for the general population except for 2- to 7-year-old children (RQc of 109.9%), implying the long-term risks of IMI were acceptable to common consumers except for children.


Assuntos
Inseticidas , Resíduos de Praguicidas , Zanthoxylum , Criança , Pré-Escolar , China , Cromatografia Líquida , Humanos , Inseticidas/análise , Neonicotinoides/análise , Nitrocompostos/análise , Resíduos de Praguicidas/análise , Medição de Risco , Espectrometria de Massas em Tandem
4.
Ecotoxicol Environ Saf ; 225: 112785, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34544021

RESUMO

Neonicotinoids are among the most widely used insecticides worldwide, and as such, have garnered increasing attention from the scientific community in regards to their potentially negative environmental impacts. Recently, the degradability of neonicotinoid in soil has gained more attentions. However, what role soil microbes play in this degradation remains vastly underexplored. In this study, we compared the capacity of soil microbes sampled from different geographic regions and fields to degrade the neonicotinoid insecticide imidacloprid. Additionally, the composition of microbiota having low, middle, and high degradation activity was analyzed via high throughput sequencing. Correlations between microbiota composition and degradation activities were analyzed and reconfirmed. The results showed that the composition of soil microbiota and their degradation activity (ranged from zero to 96.25%) varied significantly between soil samples from different geographic locations. Correlation analysis showed that Paracoccus and Achromobacter bacteria were positively correlated with high degradation activity. Imidacloprid degradation experiments using these bacteria showed that Achromobacter sp. alone exhibited degradation activity reaching and sustaining 100% by day 20 while Paracoccus sp. did not. However, combining these bacteria resulted in increased degradation activity which reached 100% at day 15 relative to that achieved by Achromobacter sp. alone. This study demonstrated the capacity of soil microbes to degrade imidacloprid, and identified two promising bacterial candidates that could be potentially used in future to reduce imidacloprid accumulation in soils.


Assuntos
Achromobacter , Inseticidas , Paracoccus , Poluentes do Solo , Bactérias , Biodegradação Ambiental , Neonicotinoides , Nitrocompostos , Solo , Microbiologia do Solo
5.
Chemosphere ; 282: 131120, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470165

RESUMO

This study evaluated the adverse effects of low-dose imidacloprid (IMI) on the characteristics of sperm from male Wistar rats. Thirty mature male rats were equally divided into three groups and orally administered vehicle (Control Group), acceptable daily intake (ADI) concentration of IMI (Group 1), and IMI at a dose 10-fold that of the ADI (Group 2) for 90 days. The findings revealed that IMI caused abnormalities in sperm concentrations and morphologies, accompanied by an imbalance of the gonadal hormone testosterone. Histopathological damage and decrease of testosterone levels were observed in testes from rats treated with IMI. However, estradiol and gonadotropin levels were unchanged after IMI treatment. IMI inhibited the activity of cytochrome P450 3A4 (CYP3A4) and left itself existed in the organism of rats. The indicators relating to sperms and CYP3A4 activity were recovered when rats were co-treated with IMI and CYP3A4 inducer rifampicin together. These results indicated that low-dose IMI exposure caused sperm abnormalities through affecting on the spermiogenesis in testis. Inhibition of CYP3A4 activity by IMI largely contributed to its sperm toxicity. Thus, IMI exposure at doses close to real-world settings resulted in sperm toxicity on rats, which might be a potential risk factor for human reproductive diseases.


Assuntos
Citocromo P-450 CYP3A , Espermatogênese , Animais , Masculino , Neonicotinoides/toxicidade , Nitrocompostos , Ratos , Ratos Wistar , Espermatozoides , Testículo , Testosterona
6.
Int J Mol Sci ; 22(16)2021 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-34445757

RESUMO

Nitro-oleic acid (NO2-OA), a nitric oxide (NO)- and nitrite (NO2-)-derived electrophilic fatty acid metabolite, displays anti-inflammatory and anti-fibrotic signaling actions and therapeutic benefit in murine models of ischemia-reperfusion, atrial fibrillation, and pulmonary hypertension. Muscle LIM protein-deficient mice (Mlp-/-) develop dilated cardiomyopathy (DCM), characterized by impaired left ventricular function and increased ventricular fibrosis at the age of 8 weeks. This study investigated the effects of NO2-OA on cardiac function in Mlp-/- mice both in vivo and in vitro. Mlp-/- mice were treated with NO2-OA or vehicle for 4 weeks via subcutaneous osmotic minipumps. Wildtype (WT) littermates treated with vehicle served as controls. Mlp-/- mice exhibited enhanced TGFß signalling, fibrosis and severely reduced left ventricular systolic function. NO2-OA treatment attenuated interstitial myocardial fibrosis and substantially improved left ventricular systolic function in Mlp-/- mice. In vitro studies of TGFß-stimulated primary cardiac fibroblasts further revealed that the anti-fibrotic effects of NO2-OA rely on its capability to attenuate fibroblast to myofibroblast transdifferentiation by inhibiting phosphorylation of TGFß downstream targets. In conclusion, we demonstrate a substantial therapeutic benefit of NO2-OA in a murine model of DCM, mediated by interfering with endogenously activated TGFß signaling.


Assuntos
Anti-Inflamatórios/uso terapêutico , Cardiomiopatia Dilatada/tratamento farmacológico , Nitrocompostos/uso terapêutico , Ácidos Oleicos/uso terapêutico , Função Ventricular Esquerda/efeitos dos fármacos , Animais , Anti-Inflamatórios/farmacologia , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/patologia , Avaliação Pré-Clínica de Medicamentos , Fibroblastos/metabolismo , Fibrose , Coração/efeitos dos fármacos , Proteínas com Domínio LIM/genética , Camundongos , Proteínas Musculares/genética , Miocárdio/metabolismo , Nitrocompostos/farmacologia , Ácidos Oleicos/farmacologia , Fator de Crescimento Transformador beta/metabolismo
7.
Int J Mol Sci ; 22(16)2021 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-34445240

RESUMO

Nitroaromatic compounds (ArNO2) maintain their importance in relation to industrial processes, environmental pollution, and pharmaceutical application. The manifestation of toxicity/therapeutic action of nitroaromatics may involve their single- or two-electron reduction performed by various flavoenzymes and/or their physiological redox partners, metalloproteins. The pivotal and still incompletely resolved questions in this area are the identification and characterization of the specific enzymes that are involved in the bioreduction of ArNO2 and the establishment of their contribution to cytotoxic/therapeutic action of nitroaromatics. This review addresses the following topics: (i) the intrinsic redox properties of ArNO2, in particular, the energetics of their single- and two-electron reduction in aqueous medium; (ii) the mechanisms and structure-activity relationships of reduction in ArNO2 by flavoenzymes of different groups, dehydrogenases-electrontransferases (NADPH:cytochrome P-450 reductase, ferredoxin:NADP(H) oxidoreductase and their analogs), mammalian NAD(P)H:quinone oxidoreductase, bacterial nitroreductases, and disulfide reductases of different origin (glutathione, trypanothione, and thioredoxin reductases, lipoamide dehydrogenase), and (iii) the relationships between the enzymatic reactivity of compounds and their activity in mammalian cells, bacteria, and parasites.


Assuntos
Bactérias/enzimologia , Proteínas de Bactérias , Citotoxinas , Elétrons , Flavoproteínas , Nitrocompostos , Oxirredutases , Animais , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Citotoxinas/química , Citotoxinas/farmacologia , Flavoproteínas/química , Flavoproteínas/metabolismo , Humanos , Nitrocompostos/química , Nitrocompostos/farmacologia , Oxirredução , Oxirredutases/química , Oxirredutases/metabolismo
8.
Anal Methods ; 13(33): 3649-3658, 2021 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-34368826

RESUMO

The development of sensitive, facile, cost-effective and eco-friendly sensors is essential for monitoring imidacloprid (IDP) residue on a large scale. Compared with popular modification of electrodes with advanced materials, electrochemical activation is promising at this point. In this paper, we found that strongly basic electrolytes (e.g. KOH and K3PO4) and applying cyclic potential during the activating process are beneficial to greatly amplify the electro-reduction response of IDP by nearly 16 times. Combining the characterization of activated electrodes with electrochemical behavior analysis of IDP, it is speculated that specific oxygen-contained functional groups were formed to bond with IDP molecules, leading to fast electron transfer kinetics. Then a sensitive IDP sensor has been developed with a low limit of detection (LOD) of 0.03 µM in the range of 0.1-100 µM. The methodological evaluation including reproducibility, stability and recovery has been also carefully studied, verifying the potential of proposed activated electrodes for application in rice samples.


Assuntos
Oryza , Eletrodos , Neonicotinoides , Nitrocompostos , Reprodutibilidade dos Testes
9.
Artigo em Inglês | MEDLINE | ID: mdl-34360075

RESUMO

Nanoparticles have applications in various fields such as manufacturing and materials synthesis, the environment, electronics, energy harvesting, and medicine. Besides many applications of nanoparticles, further research is required for toxic environmental effect investigation. The toxic effect of titanium dioxide nanoparticles on the physiology of the green alga Chlorella vulgaris was studied with a widely used pesticide, imidacloprid (IMD). Chlorella vulgaris was exposed for 120 h in Bold's basal medium to different toxic compounds, such as (i) a high concentration of TiO2 nanoparticles, 150-2000 mg/L, usually optimised in the photocatalytic degradation of wastewater, (ii) an extremely toxic pesticide for the aquatic environment, imidacloprid, in concentrations ranging from 5 to 40 mg/L, (iii) TiO2 nanoparticles combined with imidacloprid, usually used in a photocatalytic system. The results show that the TiO2 nanoparticles and IMD inhibited Chlorella vulgaris cell growth and decreased the biovolume by approximately 80% when 2 g/L TiO2 was used, meaning that the cells devised a mechanism to cope with a potentially stressful situation; 120 h of Chlorella vulgaris exposure to 40 mg/L of IMD resulted in a 16% decreased cell diameter and a 41% decrease in cell volume relative to the control sample, associated with the toxic effect of pesticides on the cells. Our study confirms the toxicity of nanoparticles through algal growth inhibition with an effective concentration (EC50) value measured after 72 h of 388.14 mg/L for TiO2 and 13 mg/L for IMD in a single-toxic system. The EC50 of TiO2 slowly decreased from 258.42 to 311.11 mg/L when IMD from 5 to 20 mg/L was added to the binary-toxic system. The concentration of TiO2 in the binary-toxic system did not change the EC50 for IMD, and its value was 0.019 g/L. The photodegradation process of imidacloprid (range of 5-40 mg/L) was also investigated in the algal medium incubated with 150-600 mg/L of titanium dioxide.


Assuntos
Chlorella vulgaris , Poluentes Químicos da Água , Neonicotinoides/toxicidade , Nitrocompostos , Titânio/toxicidade
10.
Environ Toxicol Pharmacol ; 87: 103724, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34416397

RESUMO

The testicular deficiency associated with exposure to three widely used insecticides in Egyptian agriculture was evaluated. Animals were orally treated with sub-lethal dose (1/50 of the oral LD50) of cypermethrin (CYP), imidacloprid (IMC), and chlorpyrifos (CPF) at 5, 9 and 1.9 mg/kg/day, respectively, five times a week for one month. The CYP, IMC, and CPF exposure resulted in a significant decline in animal body weight, sperm count, motility, normality, and viability with increased head and tail deformities. Significant reduction in serum testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), testis superoxide dismutase (SOD), and reduced glutathione (GSH) levels. In contrast, catalase (CAT), lipid peroxidation (LPO), and protein carbonyl content (PCC) levels were significantly stimulated. Jointly, obtained results were confirmed by microscopic examination of testis sections. The present data concluded that the CYP, IMC, and CPF have a public health impact and violently interferes with male rat reproductive system.


Assuntos
Clorpirifos/toxicidade , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Piretrinas/toxicidade , Testículo/efeitos dos fármacos , Animais , Catalase/metabolismo , Hormônio Foliculoestimulante/sangue , Glutationa/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Hormônio Luteinizante/sangue , Masculino , Carbonilação Proteica/efeitos dos fármacos , Ratos , Espermatozoides/anormalidades , Espermatozoides/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Testículo/metabolismo , Testículo/patologia , Testosterona/sangue
11.
Ecotoxicol Environ Saf ; 223: 112581, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34352576

RESUMO

The increasing use of insecticides, promoted by the intensification of agriculture, has raised concerns about their influence on the decline of bee colonies, which play a fundamental role in pollination. Thus, it is fundamental to elucidate the effects of insecticides on bees. This study investigated the damage caused by a sublethal concentration of thiamethoxam - TMX (0.0227 ng/µL of feed) in the head and midgut of Africanized Apis mellifera, by analyzing the enzymatic biomarkers, oxidative stress, and occurrence of lipid peroxidation. The data showed that the insecticide increased acetylcholinesterase activity (AChE) and glutathione-S-transferase (GST), whereas carboxylesterase (CaE3) activity decreased in the heads. Our results indicate that the antioxidant enzymes were less active in the head because only glutathione peroxidase (GPX) showed alterations. In the midgut, there were no alkaline phosphatase (ALP) or superoxide dismutase (SOD) responses and a decrease in the activity of CaE was observed. Otherwise, there was an increase in GPX, and the TBARS (thiobarbituric acid reactive substances) assay also showed differences in the midgut. The TBARS (thiobarbituric acid reactive substances) assay also showed differences in the midgut. The results showed enzymes such as CaE3, GST, AChE, ALP, SOD, and GPX, as well as the TBARS assay, are useful biomarkers on bees. They may be used in combination as a promising tool for characterizing bee exposure to insecticides.


Assuntos
Inseticidas , Nitrocompostos , Animais , Abelhas , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Oxazinas/toxicidade , Tiametoxam , Tiazóis/toxicidade
12.
Pestic Biochem Physiol ; 178: 104924, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34446200

RESUMO

The sulfoximines, as exemplified by sulfoxaflor (Isoclast™active), are a relatively new class of nicotinic acetylcholine receptor (nAChR) competitive modulator (Insecticide Resistance Action Committee [IRAC] Group 4C) insecticides that provide control of a wide range of sap-feeding insect pests. The sulfoximine chemistry and sulfoxaflor exhibits distinct interactions with metabolic enzymes and nAChRs compared to other IRAC Group 4 insecticides such as the neonicotinoids (Group 4A). These distinctions translate to notable differences in the frequency and degree of cross-resistance between sulfoxaflor and other insecticides. Most insect strains exhibiting resistance to a variety of insecticides, including neonicotinoids, exhibited little to no cross-resistance to sulfoxaflor. To date, only two laboratory-based studies involving four strains (Koo et al. 2014, Chen et al. 2017) have observed substantial cross-resistance (>100 fold) to sulfoxaflor in neonicotinoid resistant insects. Where higher levels of cross-resistance to sulfoxaflor are observed the magnitude of that resistance is far less than that of the selecting neonicotinoid. Importantly, there is no correlation between presence of resistance to neonicotinoids (i.e., imidacloprid, acetamiprid) and cross-resistance to sulfoxaflor. This phenomenon is consistent with and can be attributed to the unique and differentiated chemical class represented by sulfoxalfor. Recent studies have demonstrated that high levels of resistance (resistance ratio = 124-366) to sulfoxaflor can be selected for in the laboratory which thus far appear to be associated with enhanced metabolism by specific cytochrome P450s, although other resistance mechanisms have not yet been excluded. One hypothesis is that sulfoxaflor selects for and is susceptible to a subset of P450s with different substrate specificity. A range of chemoinformatic, molecular modeling, metabolism and target-site studies have been published. These studies point to distinctions in the chemistry of sulfoxaflor, and its metabolism by enzymes associated with resistance to other insecticides, as well as its interaction with insect nicotinic acetylcholine receptors, further supporting the subgrouping of sulfoxaflor (Group 4C) separate from that of other Group 4 insecticides. Herein is an expansion of an earlier review (Sparks et al. 2013), providing an update that considers prior and current studies focused on the mode of action of sulfoxaflor, along with an analysis of the presently available resistance / cross-resistance studies, and implications and recommendations regarding resistance management.


Assuntos
Inseticidas , Receptores Nicotínicos , Resistência a Inseticidas , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Piridinas/toxicidade , Compostos de Enxofre
13.
Pestic Biochem Physiol ; 178: 104938, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34446205

RESUMO

The adverse effects of chlorpyrifos, cypermethrin, and imidacloprid on mitochondrial dysfunction and oxidative stress biomarkers were studied in rat liver. The liver deficiency was also confirmed by histological analysis and gel electrophoresis. Each insecticide was administered orally with five doses per week for 28 days to male albino rats at 1/50 of the LD50 per insecticide. The results demonstrated that the mitochondrial dysfunction was confirmed by a significant decrease in NADH dehydrogenase and ATPase activities. Oxidative stress biomarkers include malondialdehyde (MDA), and protein carbonyl content (PCC) were significantly increased. However, superoxide dismutase (SOD) and glutathione S-transferase (GST) as antioxidant enzymes were significantly decreased in the mitochondria of the rat liver. HPLC analysis showed a significant increase of the 8-hydroxy-2'-deoxyguanosine (8-OH-2DG) as a biomarker of the DNA damage in rat liver. In addition, the residue levels of 0.96 and 0.29 µg/mL serum were found for cypermethrin and imidacloprid, respectively. However, chlorpyrifos not detected using the HPLC analysis. Blue native polyacrylamide gel electrophoresis (BN-PAGE) analysis showed a change in the pattern and sequence of complexions of the electron transport chain in liver mitochondria with treatment by such insecticides. The hepatic histological examination also showed symptoms of abnormalities after exposure to these insecticides.


Assuntos
Clorpirifos , Inseticidas , Animais , Antioxidantes/metabolismo , Clorpirifos/metabolismo , Clorpirifos/toxicidade , Inseticidas/metabolismo , Inseticidas/toxicidade , Fígado/metabolismo , Mitocôndrias , Neonicotinoides , Nitrocompostos , Estresse Oxidativo , Carbonilação Proteica , Piretrinas , Ratos
14.
J Agric Food Chem ; 69(33): 9551-9556, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34374535

RESUMO

A novel insecticide flupyrimin (FLP) with a trifluoroacetyl pharmacophore acts as an antagonist at the insect nicotinic acetylcholine receptor (nAChR). This investigation examines a hypothesis that the FLP C(O)CF3 moiety is primarily recognized by the ß subunit-face in the ligand-binding pocket (interface between α and ß subunits) of the insect nAChR. Accordingly, we evaluate the atomic interaction between a fluorine atom of FLP and the partnering amino acid side chain on the ß subunit employing a recombinant hybrid nAChR consisting of aphid Mpα2 and rat Rß2 subunits (with a mutation at T77 on the Rß2). The H-donating T77R, T77K, T77N, or T77Q nAChR enhances the FLP binding potency relative to that of the wild-type receptor, whereas the affinity of neonicotinoid imidaclprid (IMI) with a nitroguanidine pharmacophore remains unchanged. These results facilitate the establishment of the unique FLP molecular recognition at the Mpα2/Mpß1 interface structural model, thereby underscoring a distinction in its binding mechanism from IMI.


Assuntos
Afídeos , Inseticidas , Receptores Nicotínicos , Animais , Insetos , Neonicotinoides , Nitrocompostos , Ratos , Receptores Nicotínicos/genética
15.
Environ Pollut ; 289: 117813, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34332171

RESUMO

Seed coating ('seed treatment') is the leading delivery method of neonicotinoid insecticides in major crops such as soybean, wheat, cotton and maize. However, this prophylactic use of neonicotinoids is widely discussed from the standpoint of environmental costs. Growing soybean plants from neonicotinoid-coated seeds in field, we demonstrate that soybean aphids (Aphis glycines) survived the treatment, and excreted honeydew containing neonicotinoids. Biochemical analyses demonstrated that honeydew excreted by the soybean aphid contained substantial concentrations of neonicotinoids even one month after sowing of the crop. Consuming this honeydew reduced the longevity of two biological control agents of the soybean aphid, the predatory midge Aphidoletes aphidimyza and the parasitic wasp Aphelinus certus. These results have important environmental and economic implications because honeydew is the main carbohydrate source for many beneficial insects in agricultural landscapes.


Assuntos
Afídeos , Inseticidas , Animais , Agentes de Controle Biológico , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos , Oxazinas , Sementes , Soja , Tiametoxam , Tiazóis
16.
J Hazard Mater ; 418: 126391, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34329022

RESUMO

Rare studies investigated influence of neonicotinoid insecticides on the whole soil biota including non-target invertebrates and microorganisms. And less is known about the consequent intervention on soil C processes. This study aimed to decipher Collembola-fungi-bacteria interactive effects on pathways of maize C translocation, combining isotopic tracer analysis of relevant compartments with high-throughput sequencing for bacterial and fungal genetic profiles. Dinotefuran was applied at 0 or 100 µg kg-1 (a simulating residual dosage) to microcosms containing soils, Collembola and 13C labelled maize. Dinotefuran drastically reduced the density and maize-derived biomass C of Collembola, while intensifying antagonistic associations between soil organisms, with flourishing growth of Ascomycota and Actinobacteria, e.g., Streptomyces. This led to higher soil organic C (SOC) mineralization (elevated by 9.8-10.5%) across soils, attributing to the shift in microbial taxonomic and functional guild, e.g., with the increased abundance of genes aligned to cytochrome P450. Maize decomposition was controlled by Collembola that primarily fed on maize, via grazing behavior that facilitated labile maize C preferred decomposers, e.g., Xanthomonadaceae. These findings elucidate the influence of minute dinotefuran on intra-linkages between biomes (Collembola, fungi and bacteria), and highlight such legacy effects on maize and SOC mineralization.


Assuntos
Carbono , Solo , Bactérias/genética , Fungos , Guanidinas , Neonicotinoides/toxicidade , Nitrocompostos , Microbiologia do Solo , Zea mays
17.
Food Chem ; 364: 130216, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34237619

RESUMO

The double-mesoporous-layer imprinted polymer of mesoporous silica/mesoporous molecularly imprinted nanoparticles (MIP), with high specific surface area, rich porosity, excellent mass transfer rate and selectivity, were synthesized using imidacloprid (IDP) as a template. Under the optimal conditions of pH, contact time, concentration and temperature, MIP showed high adsorption capacity of 13.86 µg·mg-1 toward IDP and the imprinting factor reached 3.5. The adsorption process model including binding isotherm and kinetics was investigated. MIP exhibited excellent regeneration and its adsorption and selectivity were outstanding among its structurally pesticide analogues. The recovery of spiked IDP for MIP in fortified real samples can reach 96.0 ± 8.5% for cabbage and 105.0 ± 9.9% for apple. The limit of detection of the enrichment method can be as low as 0.037 µg·mL-1 with a good linear relationship (R2 = 0.996) from 0.30 to 10.0 µg·mL-1. The results indicated that the proposed method allowed class-specific detection of IDP in food samples.


Assuntos
Impressão Molecular , Nanopartículas , Adsorção , Neonicotinoides , Nitrocompostos , Dióxido de Silício
18.
Pest Manag Sci ; 77(11): 5202-5212, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34272799

RESUMO

BACKGROUND: The common bed bug, Cimex lectularius L., and the tropical bed bug, Cimex hemipterus (F.), are now widely regarded as important public health pests following their rapid global resurgence, largely due to insecticide resistance and an increased rate of global travel. The insecticide resistance mechanisms are well documented in C. lectularius, however, only one mechanism is validated in C. hemipterus thus far. This demands further understanding on the resistance mechanisms involved in C. hemipterus. RESULTS: Here, we identified differences in resistance to fenitrothion (organophosphate) and imidacloprid (neonicotinoid) related cuticle thickness in C. hemipterus. There is evidence of a possible association between cuticle thickness and resistance, but the association can be tenuous, likely because resistance is multifactorial in C. hemipterus. We also discovered a novel T1011 residue in domain IIS6 of the voltage-gated sodium channel that likely enhanced susceptibility to deltamethrin (pyrethroid) despite the presence of a L1014F mutation known to confer pyrethroid resistance in C. hemipterus. Our findings also confirmed that the M918I mutation enhanced resistance to pyrethroid when present with the L1014F mutation, which was consistent with a super-kdr phenotype, as reported previously. Multiple resistance mechanisms can be found within a single C. hemipterus population, and the presence of both M918I + L1014F mutations likely masked the influence of cuticle thickness in conferring resistance against deltamethrin. The elevated metabolic enzyme activities in some strains were not necessarily associated with increased insecticide resistance. CONCLUSION: This study has enhanced our understanding on the penetration resistance mechanism and target site insensitivity of sodium channels in C. hemipterus.


Assuntos
Percevejos-de-Cama , Resistência a Inseticidas , Inseticidas , Piretrinas , Canais de Sódio Disparados por Voltagem , Animais , Percevejos-de-Cama/genética , Fenitrotion , Inseticidas/farmacologia , Mutação , Neonicotinoides , Nitrocompostos , Piretrinas/farmacologia , Canais de Sódio Disparados por Voltagem/genética
19.
Chemosphere ; 284: 131327, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34216921

RESUMO

The neonicotinoids are globally used insecticides, which have been shown to cause negative impacts on birds. The current study aimed to evaluate the distribution of the neonicotinoid imidacloprid (IMI) in the tissues of a songbird and identify related physiological effects. Adults of the grayish baywing (Agelaioides baduis) were administered with a single dose of 35 mg IMI/kg, and the IMI concentration was evaluated in liver, kidney and plasma at 4, 12, 24, and 48 h after dosing. At the same time points, effects on hematological, genetic and enzymatic parameters were assessed. Results showed that IMI was absorbed before 4 h, and eliminated at 48 h, in every tissue, and the highest concentrations were detected in plasma. Baywings showed intoxication signs and reduced mobility within the first 5 min post-dosing. Hematological parameters: red blood cells, packed cell volume, hemoglobin, and their derived indices exhibited a transient elevation 24 h after dosing, which coincided with maximum concentrations of IMI in the tissues. No effects were observed on the genotoxicity parameters evaluated: micronuclei and comet assay. Treated birds exhibited an alteration of cholinesterases activity in the muscle and plasma, and of glutathione-S-transferase (GST) activity in the plasma, brain, liver, and muscle. Based on the results obtained, the combined detection of IMI and inhibition of GST activity in the plasma is suggested as a non-lethal biomarker of IMI exposure in wild birds. As efficient field monitoring depends on the availability of proven biomarkers, the current study provides valuable tools for bird conservation in agroecosystems.


Assuntos
Inseticidas , Nitrocompostos , Animais , Inseticidas/análise , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , América do Sul , Distribuição Tecidual
20.
Pestic Biochem Physiol ; 177: 104885, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34301353

RESUMO

Imidacloprid is a neonicotinoid that targets sucking pests, such as aphids and the green leaf bug and has been widely applied in wheat fields to control wheat aphids in China. To investigate the involvement of miRNAs in imidacloprid resistance, we sequenced small RNA libraries of Sitobion miscanthi Fabricius, across two different treatments using Illumina short-read sequencing technology. As a result, 265 microRNAs (miRNAs), of which 242 were known and 23 were novel, were identified. Quantitative analysis of miRNA levels showed that 23 miRNAs were significantly up-regulated, and 54 miRNAs were significantly down-regulated in the nymphs of S. miscanthi treated with imidacloprid in comparison with those of the control. Modulation of the abundances of differentially expressed miRNAs, smi-miR-316, smi-miR-1000, and smi-miR-iab-4 by the addition of the corresponding antagomir/inhibitor to the artificial diet significantly changed the susceptibility of S. miscanthi to imidacloprid. Subsequently, the post-transcriptional regulatory mechanism was conducted, smi-miR-278 and smi-miR-316 were confirmed to be participated in the post-transcriptional regulation of nAChRα1A and CYP4CJ6, respectively. The results suggested that miRNAs differentially expressed in response to imidacloprid could play a critical regulatory role in the metabolism of S. miscanthi to imidacloprid.


Assuntos
Afídeos , MicroRNAs , Animais , Afídeos/genética , China , Perfilação da Expressão Gênica , MicroRNAs/genética , Neonicotinoides/toxicidade , Nitrocompostos
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