Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 7.402
Filtrar
1.
Pestic Biochem Physiol ; 168: 104633, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32711767

RESUMO

Some quinuclidine benzamide compounds have been found to modulate nicotinic acetylcholine receptors in both mammals and insects. In particular, the quaternarization of 3-amino quinuclidine benzamide derivatives with dichloromethane gave charged N-chloromethylated quinuclidine compounds, disclosing an antagonist profile on homomeric α7 nAChRs. Here, we synthesized and studied the toxicological effect of LMA10233, a quinuclidine-borane complex analogue, the LMA10233, on the pea aphid Acyrthosiphon pisum and found that LMA10233 only exhibit proper toxicity on A. pisum larvae when applied in concentrations of over 10 µg/ml. We assessed the ability of LMA10233 to enhance the toxicity of different insecticides. When a sublethal concentration of LMA10233 was combined with the LC10 of each compound, we found a strong increase in toxicity at 24 h and 48 h of exposure for clothianidin, fipronil and chlorpyrifos, and only at 24 h for imidacloprid, acetamiprid and deltamethrin. However, when the pesticide was used at the LC50, only acetamiprid showed a synergistic effect with LMA10233. When the concentration of LMA10233 was decreased, we found that up to 80-90% of mortality was obtained due to the synergism between acetamiprid and LMA10233. No similar effect was observed with other insecticides. We conclude that such quinuclidine-borane complex compounds could increase the toxic effect of insecticides at low concentrations.


Assuntos
Boranos , Inseticidas , Praguicidas , Animais , Benzamidas , Neonicotinoides , Nitrocompostos , Quinuclidinas
2.
Pestic Biochem Physiol ; 168: 104642, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32711775

RESUMO

The Asian citrus psyllid, Diaphorina citri, is the principal vector of Huanglongbing pathogen Candidatus Liberibacter asiaticus (CLas), which causes severe economic losses to citrus industry worldwide. Use of broad-spectrum insecticides to control D. citri has resulted in considerable resistance development. Specific chemosensory proteins such as odorant binding proteins (OBPs) are potentially involved in reduced insecticide susceptibility. However, functional data on the contribution of OBPs to reduced susceptibility of D. citri are unavailable. We found that DcitOBP2 was stably expressed in different developmental stages and highly expressed in the legs, head and cuticle of D. citri. Expression of DcitOBP2 was significantly induced by 12 to 48 h of imidacloprid exposure and ranged from a 1.34- to 2.44-fold increase. RNAi of DcitOBP2 increased the susceptibility of D. citri adults to imidacloprid. The purified recombinant protein of DcitOBP2 expressed in Escherichia coli showed strong in vitro binding activity (Kd = 62.39 nM) to imidacloprid using microscale thermophoresis technology (MST). DcitOBP2 also had strong binding ability to thiamethoxam and dinotefuran but it had no response to abamectin, fenpropathrin and chlorpyrifos. The results showed that DcitOBP2 can interact with several neonicotinoid insecticides. This suggests that DcitOBP2 is involved in the decreased susceptibility of D. citri to imidacloprid. Our data reveal a new function of insect OBPs as a buffering protein that helps insects survive insecticide exposure. Our investigation may also aid in the development of new methods for resistance management of D. citri.


Assuntos
Citrus , Hemípteros , Rhizobiaceae , Animais , Neonicotinoides , Nitrocompostos , Odorantes , Doenças das Plantas
3.
Pestic Biochem Physiol ; 168: 104617, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32711778

RESUMO

The projection of plant protection products' (PPPs) toxicity to non-target organisms at early stages of their development is challenging and demanding. Recent developments in bioanalytics, however, have facilitated the study of fluctuations in the metabolism of biological systems in response to treatments with bioactives and the discovery of corresponding toxicity biomarkers. Neonicotinoids are improved insecticides that target nicotinic acetylocholine receptors (nAChR) in insects which are similar to mammals. Nonetheless, they have sparked controversy due to effects on non-target organisms. Within this context, mammalian cell cultures represent ideal systems for the development of robust models for the dissection of PPPs' toxicity. Thus, we have investigated the toxicity of imidacloprid, clothianidin, and their mixture on primary mouse (Mus musculus) neural stem/progenitor (NSPCs) and mouse neuroblastoma-derived Neuro-2a (N2a) cells, and the undergoing metabolic changes applying metabolomics. Results revealed that NSPCs, which in vitro resemble those that reside in the postnatal and adult central nervous system, are five to seven-fold more sensitive than N2a to the applied insecticides. The energy equilibrium of NSPCs was substantially altered, as it is indicated by fluctuations of metabolites involved in energy production (e.g. glucose, lactate), Krebs cycle intermediates, and fatty acids, which are important components of cell membranes. Such evidence plausibly suggests a switch of cells' energy-producing mechanism to the direct metabolism of glucose to lactate in response to insecticides. The developed pipeline could be further exploited in the discovery of unintended effects of PPPs at early steps of development and for regulatory purposes.


Assuntos
Inseticidas , Nitrocompostos , Animais , Guanidinas , Homeostase , Metabolômica , Camundongos , Neonicotinoides , Sistema Nervoso , Células-Tronco , Tiazóis
4.
Environ Pollut ; 264: 114793, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32559875

RESUMO

The neonicotinoid imidacloprid (IMI) is one of the most extensively applied neuro-active insecticides worldwide and continues to enter surface waters in many countries despite a recent ban for outdoor use in the EU. Yet little is known about ecotoxicological effects on non-target benthic freshwater species exposed to environmentally relevant concentrations of IMI and its marketed products. The aim of the present study was to narrow this gap by assessing effects of pure IMI and its commercial formulation Confidor® on the aquatic oligochaete Lumbriculus variegatus, a key species in freshwater sediments. To this end, we determined dose-response relationships in 24 h toxicity tests, bioconcentration during 24 h and 5 d of exposure to 0.1, 1 and 10 µg IMI L-1, and physiological stress responses by measuring glutathione S-transferase, glutathione reductase and catalase activity in the same conditions. Maximum neonicotinoid concentrations reported from the field were lethal to L. variegatus within 24 h (LC50 of 65 and 88 µg IMI L-1 in pure form and as active ingredient of Confidor®, respectively). At sub-lethal exposure concentrations, tissue content of IMI significantly increased with exposure time. The observed bioconcentration factors (BCFs) were far above the water octanol coefficient (KOW), indicating a potentially large underestimation of IMI bioaccumulation when based on KOW. Activities of biotransformation and antioxidant enzymes indicated attempts of L. variegatus to counter xenobiotic-triggered oxidative stress to very low IMI and Confidor® concentrations. Together, our data add significantly to growing evidence that the continued proliferation of neonicotinoids require increased efforts in environmental risk assessment, especially in view of species-specific differences in sensitivities to the insecticide and possibly to additives of commercial formulations.


Assuntos
Inseticidas/análise , Poluentes Químicos da Água/análise , Água Doce , Neonicotinoides , Nitrocompostos
5.
Pestic Biochem Physiol ; 167: 104601, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32527429

RESUMO

Dinotefuran, the third-generation neonicotinoid, has been applied against melon/cotton aphid Aphis gossypii Glover in China. The risk of resistance development, cross-resistance pattern and potential resistance mechanism of dinotefuran in A. gossypii were investigated. A dinotefuran-resistant strain of A. gossypii (DinR) with 74.7-fold resistance was established by continuous selection using dinotefuran. The DinR strain showed a medium level of cross resistance to thiamethoxam (15.2-fold), but no cross resistance to imidacloprid. The synergism assay indicated that piperonyl butoxide and triphenyl phosphate showed synergistic effects on dinotefuran toxicity to the DinR strain with a synergistic ratio of 8.3 and 2.5, respectively, while diethyl maleate showed no synergistic effect. The activities of cytochrome P450 monooxygenase and carboxylesterase were significantly higher in DinR strain than in susceptible strain (SS). Moreover, the gene expression results showed that CYP6CY14, CYP6CY22 and CYP6UN1 were significantly overexpressed in DinR strain compared with SS strain. The expression of CYP6CY14 was 5.8-fold higher in DinR strain than in SS strain. Additionally, the transcription of CYP6CY14, CYP6CY22 and CYP6UN1 in A. gossypii showed dose- and time-dependent responses to dinotefuran exposure. Furthermore, knockdown of CYP6CY14, CYP6CY22 and CYP6UN1 via RNA interference (RNAi) significantly increased mortality of A. gossypii, when A. gossypii was treated with dinotefuran. These results demonstrated the overexpression of CYP6CY14, CYP6CY22 and CYP6UN1 contributed to dinotefuran resistance in A. gossypii.


Assuntos
Afídeos , Cucurbitaceae , Inseticidas , Animais , China , Sistema Enzimático do Citocromo P-450 , Guanidinas , Resistência a Inseticidas , Neonicotinoides , Nitrocompostos
6.
Toxicon ; 183: 44-50, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32464148

RESUMO

3-nitropropionic acid (3-NP) is a mycotoxin widely used to produce a rat model of Huntington's disease. While there are numerous studies on the effect of this neurotoxin, still further investigation is required to understand the influence of this toxin on different regions of the brain. In the present study, there are two groups of rats of which one is treated with 3-NP. Behavioral, stereological and immunohistochemical analyses were conducted. The results show that locomotor activity is largely affected and anxiety is induced up to a certain level, but there is no gross manifestation of deficit in memory. Microscopic observations illustrate damages in the hippocampus and other parts of the brain. Astrogliosis and glial scars were another finding of this study. In conclusion, although 3-NP can be used as a model of Huntington's disease, it exerts a disseminated effect on different regions of the brain.


Assuntos
Micotoxinas/toxicidade , Nitrocompostos/toxicidade , Propionatos/toxicidade , Animais , Encéfalo , Cerebelo/efeitos dos fármacos , Gliose , Hipocampo/efeitos dos fármacos , Masculino , Córtex Pré-Frontal/efeitos dos fármacos , Ratos , Ratos Wistar
7.
Environ Sci Pollut Res Int ; 27(22): 28066-28076, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32405953

RESUMO

Effects of imidacloprid and iprodione, isolated and in mixture, were assessed by using seed germination and root growth test, flow cytometry, and chromosomal aberrations test on Allium cepa root meristem. The highest concentrations of imidacloprid, including field concentration, increased the frequency of sub-G1 particles, decreased the frequency of nuclei in G2/M, increased the coefficient of variation of G1 (CVG1) and the frequency of aberrant cells, and inhibited the mitotic index culminating in the reduction in root length. All doses of iprodione also presented cytogenotoxic action. The highest concentration of the fungicide affected the growth of A. cepa roots. In response to exposure to pesticide mixtures, the cell cycle of A. cepa was blocked in the G1 phase. The mixtures with low doses of the pesticides significantly decreased the mitotic index, and as a consequence, the genotoxicity was reduced. In the mixtures with the highest doses of the agrochemicals, the blockage of the cell cycle was insufficient for damage repair, resulting in a significant increase of chromosomal aberrations. The results suggest caution in the use of pesticides doses that induce cytological abnormalities in non-target organisms.


Assuntos
Cebolas , Praguicidas , Aminoimidazol Carboxamida/análogos & derivados , Aberrações Cromossômicas , Dano ao DNA , Humanos , Hidantoínas , Meristema , Índice Mitótico , Neonicotinoides , Nitrocompostos , Raízes de Plantas
8.
Chemosphere ; 256: 126986, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32445995

RESUMO

Systemic neurotoxic insecticides are widely used to control aphid pests worldwide and their potential non-target effects on aphid predators are often unknown. Behavioral responses linked to biological control services are crucial when assessing the compatibility of chemicals with biocontrol organisms. This is particularly relevant for insecticides at low and sublethal concentrations. We studied the acute toxicity and the sublethal effect on the voracity of the generalist predator Harmonia axyridis (Coleoptera: Coccinellidae) caused by the exposure to three systemic insecticides routinely used against aphids. The tested insecticide concentrations were the Lethal Concentration 50% (LC50), 20% (LC20) and 1% (LC1) estimated for the target pest Aphis gossypii (Hemiptera: Aphididae) in a companion study. The survival and the voracity differed among the tested chemicals and concentrations, but only thiamethoxam at LC50 caused a significant predator mortality, and individuals that survived showed a reduced predation rate. The predators showed a density independent functional response after the exposure to most of the insecticide-concentration combinations, while an inverse density dependence of the prey consumption rate was observed for coccinellids exposed to sulfoxaflor and thiamethoxam at their lowest tested concentration. The estimated parameters, i.e., the attack rate and the prey handling time, were affected at higher concentrations by both imidacloprid and sulfoxaflor. These findings stress the importance of carefully evaluating side effects of insecticides at very low concentrations on beneficial arthropods in the risk assessment schemes for sustainable pest control programmes.


Assuntos
Afídeos/efeitos dos fármacos , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Animais , Afídeos/fisiologia , Besouros/efeitos dos fármacos , Dose Letal Mediana , Comportamento Predatório/efeitos dos fármacos , Piridinas , Compostos de Enxofre , Tiametoxam
9.
Chemosphere ; 255: 126848, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388255

RESUMO

Insensitive high explosives are increasingly being used to replace more sensitive formulations, however large quantities of environmentally hazardous wastewater are generated from loading, assembling and packing processes. Currently, there is limited literature regarding the treatment of wastewater contaminated with these hazardous insensitive high explosive materials such as 1,3,5-trinitroperhydro- 1,3,5-triazine (RDX), 2,4-dinitoranisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO). The preferred method of explosive wastewater treatment is adsorption by activated carbon, usually through treatment columns or fluidised beds that are simple to operate and cost effective. The aim of this research was to assess whether commercially available activated carbons would be suitable and economically viable to treat explosive wastewater containing RDX, DNAN and NTO. Bottle point tests were used to determine adsorption capacity and adsorption kinetics for the individual insensitive high explosives with three different activated carbons. Equilibrium data were fitted to the Langmuir, Freundlich and Temkin isotherms to determine the mechanisms of adsorption. Six hour bottle point tests for a mixture of the three insensitive high explosive constituents were used to consider possible preferential adsorption. As expected, RDX and DNAN were adsorbed at concentrations up to 40 mg.L-1 and 150 mg.L-1 respectively by the activated carbons tested, demonstrating the viability of treatment by adsorption. However, at the high concentrations of NTO expected in wastewater (1400 mg.L-1) activated carbons were rapidly saturated, suggesting that treatment of NTO contaminated wastewater would require prohibitively large quantities of activated carbon compared to RDX and DNAN.


Assuntos
Anisóis/química , Carvão Vegetal/química , Nitrocompostos/química , Triazinas/química , Triazóis/química , Adsorção , Substâncias Explosivas , Cinética , Modelos Químicos , Águas Residuárias
10.
Chemosphere ; 255: 126778, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388266

RESUMO

The predatory bug Orius sauteri (Poppius) is currently one of the most important beneficial arthropods in Northeast Asia and used as a biological control agent of several small pest arthropods including Frankliniella occidentalis (Pergande). Two neonicotinoid chemical insecticides, acetamiprid and imidacloprid, mainly used in China as chemical control on F. occidentalis, although applied at sublethal concentrations in the field or greenhouse to protect beneficial arthropods, still may affect the predator O. sauteri. The objective of present work is to assess the long-term effects of 24-h exposure time to these two insecticides on the life-cycle of O. sauteri at application rates similar to the laboratory 24-h LC10, LC20 and LC30 of O. sauteri. Results showed that acetamiprid and imidacloprid at all tested concentrations significantly decreased the fecundity of O. sauteri females, while the effect of acetamiprid was higher than that of imidacloprid. Moreover, the oviposition period and longevity of O. sauteri to both insecticides shortened. The sublethal effects on the first progeny (F1 generation) were also found to increase nymphal mortality, shorten adult longevity and reduce fecundity. However, all treatments of acetamiprid and imidacloprid at the concentration of LC10, LC20 and LC30 caused no significant effect on the developmental time of different nymphal stages and sex ratio of the F1 generation. This paper is the first one that assesses the compatibility between neonicotinoid insecticides and O. sauteri, and shows that the application of acetamiprid and imidacloprid likely interferes with the population dynamic of O. sauteri.


Assuntos
Hemípteros/fisiologia , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Animais , China , Feminino , Fertilidade/efeitos dos fármacos , Heterópteros/efeitos dos fármacos , Ninfa/efeitos dos fármacos , Oviposição/efeitos dos fármacos
11.
Pestic Biochem Physiol ; 165: 104554, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32359545

RESUMO

Dinotefuran (DTF) is a systemic neonicotinoid insecticide characterized by a tetrahydrofuran ring. In the present study, we examined the characteristics of DTF binding to native nicotinic acetylcholine receptors (nAChRs) expressed in the American cockroach Periplaneta americana using radioligand-binding methods. The Scatchard analysis, using [3H]imidacloprid (IMI), indicated that IMI has a single class of high-affinity binding sites in the P. americana nerve cord. In contrast, the Scatchard analysis using [3H]DTF indicated that DTF has two different classes of binding sites. Both DTF and IMI were found to bind to one of the classes, for which DTF showed low affinity. The other class, for which DTF showed high affinity, was localized in the abdominal nerve cord but not in the thoracic nerve cord. IMI showed low affinity for the high-affinity DTF binding sites. Our data suggest that DTF binds with high affinity to a nAChR subtype distinct from the high-affinity subtype for IMI. This difference might be responsible, at least in part, for the difference in resistance development to DTF and IMI in P. americana.


Assuntos
Baratas , Inseticidas , Periplaneta , Receptores Nicotínicos , Animais , Sítios de Ligação , Guanidinas , Neonicotinoides , Nitrocompostos
12.
Pestic Biochem Physiol ; 165: 104538, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32359560

RESUMO

Imidacloprid is very effective in controlling Nilaparvata lugens Stål, which severely damages rice plants. Following heavy imidacloprid use, imidacloprid-resistant N. lugens, which showed cross-resistance to other neonicotinoids, appeared. We used the baculovirus/Sf9 expression system to express CYP6ER1 variants carrying A375del + A376G (del3) mutations, either with or without T318S mutation, which confer imidacloprid resistance in N. lugens. These CYP6ER1 variants metabolized imidacloprid but did not metabolize dinotefuran. Moreover, Drosophila expressing a CYP6ER1 variant carrying T318S + del3 mutations were resistant to imidacloprid, with a resistance ratio of 288.7, whereas the resistance ratio to dinotefuran was 3.6. These findings indicate that N. lugens has a low level of resistance to dinotefuran, and the increase of resistance is slow. We also studied the metabolism of other neonicotinoids, as well as sulfoxaflor and flupyradifurone, by CYP6ER1 variants carrying del3 mutations, either with or without the T318S mutation. Sulfoxaflor, was not metabolized by either CYP6ER1-del3 or CYP6ER1-T318Sdel3 variants. However, these variants did metabolize flupyradifurone. This study sheds light on the substrate selectivity of CYP6ER1 variants.


Assuntos
Hemípteros , Inseticidas , Animais , Resistência a Inseticidas , Neonicotinoides , Nitrocompostos
13.
Pestic Biochem Physiol ; 166: 104582, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32448428

RESUMO

A key to effective insect pest management and insecticide resistance management is to provide growers with a range of new tools as potential alternatives to existing compounds or approaches. Sulfoxaflor (Isoclast™ active) is a new sulfoximine insecticide which is active on a broad range of sap-feeding insects, including species that have reduced susceptibility to currently used insecticides, such as imidacloprid from the neonicotinoid class. Sulfoxaflor (SFX) and imidacloprid (IMI) were tested in laboratory bioassays to compare the susceptibility of field populations of green peach aphid, Myzus persicae (Sulzer), exhibiting varying degrees of resistance involving an alteration (R81T) to the insect nicotinic acetylcholine receptor. The LC50 values for M. persicae exposed to SFX ranged from 0.09 to 1.31 (mg litre-1), whereas when the same populations were exposed to IMI the LC50 values ranged from 0.6 to 76.2 (mg litre-1). M. persicae were significantly more sensitive to SFX as compared to IMI for nine of the 13 populations tested. For M. persicae populations confirmed to be homozygous susceptible (ss) or heterozygous rs) for the R81T point mutation, there was no significant differences in the observed LC50 values for either SFX or IMI relative to the susceptible reference population (15LP1). However, in all M persicae populations that were homozygous (rr) for the R81T point mutation, susceptibility was significantly less to IMI as compared to the reference population with resistance ratios ranging from 22.1 to 63.5-fold. In contrast, only one homozygous resistant population (15MP9) exhibited a statistically significant change in susceptibility (RR = 10-fold) to SFX as compared to the reference population, which was far less than the 56-fold observed for imidacloprid in that same population. Thus, this study indicates there is no specific correlation between the laboratory efficacy of SFX and IMI in field collected populations in Spain displaying varying degrees of resistance to IMI. Furthermore, the presence of target site resistance in M. persicae to IMI, in the form of the R81T mutation, does not a priori translate to a reduction in sensitivity to sulfoxaflor. Consequently, SFX can be an effective tool for use in insect pest management programs for green peach aphid. These data also serve as a baseline reference for green peach aphid sensitivity to SFX prior to commercial uses in Spain.


Assuntos
Afídeos , Prunus persica , Receptores Nicotínicos , Animais , Mutação , Neonicotinoides , Nitrocompostos , Piridinas , Espanha , Compostos de Enxofre
14.
Sci Total Environ ; 729: 138276, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32361427

RESUMO

Imidacloprid (IMI) is used in integrated aquaculture systems for pest control and the toxicity of IMI to non-target aquatic animals such as fish and microcrustaceans has been recognised. However, knowledge about the toxic effect of IMI on commercial crabs is still scarce. In the present study, effects of IMI on the acute toxicity, antioxidative status, detoxification systems and gut microbiota in Chinese mitten crab, Erocheir sinensis were investigated. In the present study, the 96-h LC50 of IMI for E. sinensis was 24.97 mg/L. Under sublethal exposure, superoxide dismutase (SOD) activities increased under low concentration (LC, 5 µg/L) and median concentration (MC, 50 µg/L) exposure, but decreased in high concentration group (HC, 500 µg/L). Activities of catalyse (CAT) decreased in a dose-dependent manner. Detoxification-related enzymes aminopyrine N-demethylase (APND) and erythromycin N-demethylase (ERND) increased in all treatments whereas glutathione-S-transferase (GST) decreased dose-dependently. The relative mRNA expression of the cytochrome P4502 (cyp2) gene was induced significantly in LC and HC groups while no significant change was observed in cytochrome P4503 (cyp3) gene. The expression of gst was also significantly decreased in HC group. Up-regulation of heat shock protein hsp70 and 90 was observed in MC and HC groups whereas hsp60 up-regulated only in LC group. In addition, significant changes of composition of microbial communities at both phylum and genus levels were found in this test. In particular, beneficial bacteria were found to decrease and pathogens increased after exposure to IMI. These results indicate that high concentration of IMI could induce oxidative stress and suppress the detoxification system mainly by down-regulation of gst mRNA expression, inhibition of enzyme activities and dysbiosis of gut microbiota.


Assuntos
Braquiúros , Microbioma Gastrointestinal , Animais , Neonicotinoides , Nitrocompostos , Estresse Oxidativo
15.
Environ Monit Assess ; 192(6): 403, 2020 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-32472431

RESUMO

Impact of organic manures, viz., composted coir pith, press mud, sugarcane trash, and farmyard manure (FYM) on the persistence of imidacloprid in the sandy clay loam soil of tropical sugarcane crop ecosystem, was studied by employing rapid sample preparation method and reversed phase HPLC. The recoveries of the method employed to determine the residues of imidacloprid in the soil were in the range of 94.5 ± 7.02-97.3 ± 2.94% across the five levels of fortification ranged between 0.005 and 0.5 µg/g. Imidacloprid was observed to persist in the soil manured with FYM and composted coir pith for 30 days with the half-life of 7.62 and 7.0 days, respectively as against 21 days with the half-life of 6.66 days in the non-manurial soil. The comparatively longer persistence of imidacloprid in the FYM and composted coir pith-applied soils was attributed to reduced leaching from the plow layer due to the adsorption of insecticide molecules by the added organic manures.


Assuntos
Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Saccharum , Poluentes do Solo/toxicidade , Argila , Ecossistema , Monitoramento Ambiental , Esterco , Areia , Solo
16.
Sci Total Environ ; 723: 138056, 2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32224397

RESUMO

Neonicotinoids are the largest group of systemic insecticides worldwide and are most commonly applied as agricultural seed treatments. However, little is known about the extent to which farmland birds are exposed to these compounds during standard agricultural practices. This study uses winter cereal, treated with the neonicotinoid clothianidin, as a test system to examine patterns of exposure in farmland birds during a typical sowing period. The availability of neonicotinoid-treated seed was recorded post-sowing at 39 fields (25 farms), and camera traps were used to monitor seed consumption by wild birds in situ. The concentration of clothianidin in treated seeds and crop seedlings was measured via liquid chromatography-tandem mass spectrometry, and avian blood samples were collected from 11 species of farmland bird from a further six capture sites to quantify the prevalence and level of clothianidin exposure associated with seed treatments. Neonicotinoid-treated seeds were found on the soil surface at all but one of the fields surveyed at an average density of 2.8 seeds/m2. The concentration of clothianidin in seeds varied around the target application rate, whilst crop seedlings contained on average 5.9% of the clothianidin measured in seeds. Exposure was confirmed in 32% of bird species observed in treated fields and 50% of individual birds post-sowing; the median concentration recorded in positive samples was 12 ng/mL. Results here provide clear evidence that a variety of farmland birds are subject to neonicotinoid exposure following normal agricultural sowing of neonicotinoid-treated cereal seed. Furthermore, the widespread availability of seeds at the soil surface was identified as a primary source of exposure. Overall, these data are likely to have global implications for bird species and current agricultural policies where neonicotinoids are in use, and may be pertinent to any future risk assessments for systemic insecticide seed treatments.


Assuntos
Grão Comestível/química , Inseticidas/análise , Animais , Aves , Fazendas , Guanidinas/análise , Neonicotinoides , Nitrocompostos/análise , Sementes/química , Tiazóis
17.
Sci Total Environ ; 724: 137913, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32251880

RESUMO

Dissolved organic matter (DOM) strongly influences the photodegradation of organic pollutants, varying depending on the structure of DOM. With the wide application of biochar, increasing amounts of DOM is released from biochar to the environment, which has different structural characteristics compared to natural DOM. In this study, DOM was derived from maize straw (MS) and pig manure (PM) and biochars by pyrolyzing MS and PM at 300 °C and 500 °C and the optical characteristics of DOM before and after phototransformation were explored via ultraviolet-visible spectroscopy and excitation-emission matrix fluorescence. Photodegradation of an insecticide, imidacloprid (IMI) in the presence of DOM was examined. The results showed that DOM derived from biochar obtained by pyrolyzing MS and PM mainly contained two identified fluorescent components and high pyrolysis temperature (500 °C) was associated with low molecular weight, small light-screening effects and great aromaticity of the DOM. After exposure to UV light, the aromaticity and molecular weight of the DOM declined due to phototransformation. Significant enhancement was observed in IMI photodegradation in the presence of biochar-derived DOM, and the enhancement was the greatest with DOM derived from pig manure biochar pyrolyzed at 500 °C. In addition to the light shielding effect, the 1O2 generated from DOM played an important role in the phototransformation of IMI and DOM. The loss of the nitro group and oxidation at the imidazolidine ring were the main photodegradation pathways for IMI. This study expands our understanding of the fate of biochar-derived DOM and its effects on the fate of coexisting organic pollutants.


Assuntos
Carvão Vegetal , Raios Ultravioleta , Animais , Neonicotinoides , Nitrocompostos , Fotólise , Suínos
18.
Sci Total Environ ; 725: 138328, 2020 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-32294586

RESUMO

The wide application of neonicotinoid insecticides in soil may affect soil microbial community, yet the information is limited. This study first reports the effects of thiamethoxam and dinotefuranon on soil microbial community. Soil from a forest land was collected and spiked with different nominal levels (0.02 mg kg-1, 0.2 mg kg-1 and 2.0 mg kg-1) of thiamethoxam and dinotefuran, respectively, and cultivated for 112 days. During the study, concentrations of the two neonicotinoids and their potential degradation products were monitored by LC-MS/MS. At day 112, the soils were analyzed for genetic profile by high-throughput sequencing and carbon metabolic profile by Biolog-ECO plate. The results showed that thiamethoxam and dinotefuran were both attenuated during the study with rate constants being 0.008-0.017 d-1 and 0.024-0.032 d-1, respectively, and biodegradation played an important role. As compared to the blank control, the exposure to the studied two neonicotinoids changed the microbial community, and the changes were influenced by both the type of neonicotinoid and the level of exposure. As compared to the blank control, the relative abundances of phyla Gemmatimonadetes and OD1 decreased under most exposed conditions, while the relative abundances of Chloroflexi and Nitrospirae increased under most exposed conditions. The community transition changed the functional potential, particularly carbon metabolism (mostly decreased) and nitrogen metabolism (mostly increased). As compared to the blank control, the utilization of total 31 carbon sources (including six categories) was increased under low exposure to thiamethoxam, but was decreased under all other exposed conditions. Low exposure to dinotefuran stimulated the utilization of three categories of carbon sources (amines, carbohydrates and phenolic compounds). Low exposure to both neonicotinoids increased the community diversity, while middle and high exposure to both neonicotinoids decreased the community diversity. These findings provide new insights into the effects of neonicotinoids on microbial community in soil.


Assuntos
Inseticidas/análise , Microbiota , Cromatografia Líquida , Guanidinas , Neonicotinoides , Nitrocompostos , Oxazinas , Solo , Espectrometria de Massas em Tandem , Tiametoxam , Tiazóis
19.
Pestic Biochem Physiol ; 164: 122-129, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32284117

RESUMO

Imidacloprid (IMI) is a widely used neonicotinoid pesticide in the world, its environmental and human health risk has particularly attracted the attention of researchers. Caffeic acid phenethyl ester (CAPE), an active polyphenol of propolis, has many pharmacological activities including free radical scavenger, anti-inflammatory, and anti-oxidant. In this study, protective effect of CAPE against IMI induced liver injury in mice was performed. Administration of 1 and 2.5 mg/kg CAPE markedly prevented serum AST and ALT increase in 5 mg/kg IMI-induced mice. CAPE significantly downregulated liver NO generation and lipid peroxidation, and upregulated glutathione, catalase, superoxide dismutase and glutathione peroxidase in a dose-dependent manner in liver of IMI-induced mice. Endoplasmic reticulum stress represented by the swelling of endoplasmic reticulum was observed by transmission electron microscope in IMI group. Pretreatment of 2.5 mg/kg CAPE significantly attenuated the endoplasmic reticulum stress induced by IMI in liver. Western blot analysis illustrated that pretreatment of CAPE downregulated the upregulation of TNF-α and IFN-γ induced by IMI in liver of mice. Moreover, the increase of positive apoptotic hepatocytes further suggested apoptosis might be involved in IMI-induced hepatotoxicity. Pretreatment of 1 and 2.5 mg/kg CAPE significantly decreased positive apoptotic hepatocytes, suggested that CAPE prevented apoptosis in liver of IMI-induced mice. In conclusion, CAPE prevented liver injury in IMI-induced mice via attenuation of oxidative stress, endoplasmic reticulum stress, inflammation and apoptosis. Our findings may have broad biological and environmental implications for future research on the therapeutic strategy to prevent liver injury induced by pesticides.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Estresse do Retículo Endoplasmático , Animais , Antioxidantes , Apoptose , Ácidos Cafeicos , Humanos , Inflamação , Camundongos , Neonicotinoides , Nitrocompostos , Estresse Oxidativo , Álcool Feniletílico/análogos & derivados
20.
Pestic Biochem Physiol ; 164: 183-190, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32284125

RESUMO

Imidacloprid (IMD) is a neonicotinoid insecticide widely used in crops, pets, and on farm animals for pest control, which can cause hepatotoxicity in animals and humans. In a previous study using isolated rat liver mitochondria, we observed that IMD inhibited the activity of FoF1-ATP synthase. The aim of this study was to evaluate the effects of IMD on rat isolated hepatocytes and perfused rat liver, besides the influence of its biotransformation on the toxicological potential. For the latter goal, rats were pretreated with dexamethasone or phenobarbital, two classical cytochrome P-450 stimulators, before hepatocytes isolation or liver perfusion. IMD (150 and 200 µM) reduced state 3 mitochondrial respiration in digitonin-permeabilized cells that were energized with glutamate plus malate but did not dissipate the mitochondrial membrane potential. In intact (non-permeabilized) hepatocytes, the intracellular ATP concentration and cell viability were reduced when high IMD concentrations were used (1.5-3.0 mM), and only in cells isolated from dexamethasone-pretreated rats, revealing that IMD biotransformation increases its toxicity and that IMD itself affects isolated mitochondria or mitochondria in permeabilized hepatocytes in concentrations that do not affect mitochondrial function in intact hepatocytes. Coherently, in the prefused liver, IMD (150 and 250 µM) inhibited gluconeogenesis from alanine, but without affecting oxygen consumption and urea production, indicating that such effect was not of mitochondrial origin. The gluconeogenesis inhibition was incomplete and occurred only when the rats were pretreated with phenobarbital, signs that IMD biotransformation was involved in the observed effect. Our findings reveal that changes in hepatic energy metabolism may be acutely implicated in the hepatotoxicity of IMD only when animals and humans are exposed to high levels of this compound, and that IMD metabolites seem to be the main cause for its toxicity.


Assuntos
Hepatócitos , Fígado , Animais , Biotransformação , Neonicotinoides , Nitrocompostos , Ratos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA