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1.
Dis Aquat Organ ; 142: 47-53, 2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33210611

RESUMO

An unusually high mortality rate due to verminous (Philometra rubra) coelomitis was documented in wild-hatched striped bass Morone saxatilis raised in a fish hatchery as part of a stock restoration program. To decrease the parasitic burden and therefore potentially minimize mortality, the effectiveness of 2 different anthelmintics was evaluated. Two trials were conducted on wild-collected fingerlings naturally infected by P. rubra. In 2006, 144 yearling fish were randomly assigned to 4 experimental groups: (1) levamisole (Levasol®) at 2 mg l-1 via immersion for 8 h once weekly for 3 wk; (2) levamisole at a dose of 2.5 mg kg-1 biomass via feed once daily for 7 d; (3) emamectin benzoate (Slice®) at a dose of 0.05 mg kg-1 biomass via feed once daily for 7 d; and (4) control. Emamectin successfully eliminated live nematodes in 84.9% of the fish, whereas the administration of levamisole, either via immersion or feed, was not successful in significantly reducing the number of live P. rubra. In 2007, the administration of the same dosage of emamectin to approximately 1000 naturally infected yearling striped bass was associated with a 100% mortality rate of P. rubra in the 30 fish randomly examined 5 wk after the beginning of the treatment. Results of these trials indicate that, at the dosage used, the administration of emamectin at the end of the summer is safe for striped bass yearlings and considerably reduces the prevalence and intensity of the infection by this parasite.


Assuntos
Anti-Helmínticos , Bass , Nematoides , Animais , Cavalos , Ivermectina/análogos & derivados
2.
Exp Parasitol ; 218: 107998, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32941889

RESUMO

The aims of this study were to evaluate the efficacy of two injectable formulations of doramectin (DRM) against Psoroptes ovis in sheep infested under controlled experimental conditions and to characterize the DRM plasma disposition kinetics in the infested animals. To this end, sheep were experimentally infested with a P. ovis strain from a farm with a history of treatment failure, and then treated either with DRM 1% (traditional preparation) on days 0 and 7 or with DRM 3.15% (long-acting formulation) on day 0. The efficacy of each treatment was calculated by counting live mites in skin scrapings. Plasma samples were obtained from each animal and DRM concentrations were measured by HPLC. After the two doses of DRM 1%, the maximum efficacy (98.8%) was reached on day 28, whereas after the single dose of DRM 3.15%, the maximum efficacy (100%) was reached on day 35 and ratified on day 42. The long-acting formulation allowed obtaining higher exposure and more sustained concentrations of DRM than the traditional preparation. Although both DRM formulations studied were effective according to international protocols, they did not reach 100% effectiveness in the time required for approved pharmaceutical products against sheep scab, according to Argentine regulations.


Assuntos
Inseticidas/uso terapêutico , Ivermectina/análogos & derivados , Infestações por Ácaros/veterinária , Psoroptidae/efeitos dos fármacos , Doenças dos Ovinos/tratamento farmacológico , Animais , Disponibilidade Biológica , Feminino , Meia-Vida , Injeções Subcutâneas/veterinária , Inseticidas/administração & dosagem , Inseticidas/sangue , Inseticidas/farmacologia , Ivermectina/administração & dosagem , Ivermectina/sangue , Ivermectina/farmacologia , Ivermectina/uso terapêutico , Masculino , Infestações por Ácaros/tratamento farmacológico , Psoroptidae/crescimento & desenvolvimento , Ovinos , Doenças dos Ovinos/parasitologia
3.
Bull Environ Contam Toxicol ; 105(4): 582-587, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32948914

RESUMO

Oreochromis niloticus was exposed to 10.0 ppb of organophosphate insecticide chlorpyrifos (CPF) and avermectin insecticides abamectin (ABM) and emamectin benzoate (EB) for 48 and 96 h. RBC and Hb decreased in CPF- and ABM-exposed fish after 96-h. Plasma ALT, AST, cortisol, and glucose increased in 96-h CPF-, ABM- and EB-exposed fish, while plasma ions declined in 96-h CPF-exposed ones. Insecticides caused alterations in liver oxidative stress parameters. In fish exposed to CPF, CAT increased after 48-h whereas it decreased after 96-h. Also, CAT declined in 48- and 96-h ABM-exposed fish, whereas it elevated in 48-h EB-exposed ones. Insecticides caused decreases in SOD at 48- and 96-h and in GR after 96-h. GSH elevated in CPF-exposed fish after 48-h, while it decreased in all the tested insecticide exposures after 96-h. Malondialdehyde of fish exposed to insecticides for 96-h increased. Consequently, toxic effects of insecticides on O. niloticus were generally as CPF > ABM > EB.


Assuntos
Clorpirifos/toxicidade , Ciclídeos , Inseticidas/toxicidade , Ivermectina/análogos & derivados , Poluentes Químicos da Água/toxicidade , Animais , Análise Química do Sangue/veterinária , Testes Hematológicos/veterinária , Ivermectina/toxicidade , Fígado/efeitos dos fármacos , Fígado/enzimologia , Oxirredução , Distribuição Aleatória , Testes de Toxicidade Aguda/veterinária
4.
Environ Pollut ; 265(Pt B): 114313, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32806434

RESUMO

Bees are considered as important providers of ecosystem services, acting via pollination process in crops and native plants, and contributing significantly to the maintenance of biodiversity. However, the decrease of bee's population has been observed worldwide and besides other factors, this collapse is also related to the extensive use of pesticides. In this sense, studies involving the assessment of adverse effects and the uptake of pesticides by bees are of great concern. This work presents an analytical method for the determination of the insecticide abamectin and the fungicide difenoconazole in the stingless bee Melipona scutellaris exposed via oral and topic to endpoints concentrations of active ingredients (a.i.) alone and in commercial formulations and the discussion about its mortality and uptake. For this purpose, QuEChERS (Quick, Easy, Cheap, Efficient, Rugged and Safe) acetate modified method was used for extraction and pesticides were determined by LC-MS/MS. The validation parameters have included: a linear range between 0.01 and 1.00 µg mL-1; and LOD and LOQ of 0.038 and 0.076 µg g-1 for abamectin and difenoconazole, respectively. The uptake of tested pesticides via oral and topic was verified by the accumulation in adult forager bees, mainly when the commercial product was tested. Mortality was observed to be higher in oral exposure than in topic tests for both pesticides. For abamectin in a commercial formulation (a.i.) no differences were observed for oral or topic exposure. On the other hand, for difenoconazole, topic exposure had demonstrated higher accumulation in bees, according to the increase of received dose. Through the results, uptake and the possible consequences of bioaccumulated pesticides are also discussed and can contribute to the knowledge about the risks involving the exposure of bees to these compounds.


Assuntos
Ecossistema , Espectrometria de Massas em Tandem , Animais , Abelhas , Cromatografia Líquida , Dioxolanos , Ivermectina/análogos & derivados , Triazóis
5.
PLoS One ; 15(8): e0236143, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790679

RESUMO

The focus of gastro-intestinal parasite control in the sheep industry is increasingly on finding a balance between maintaining productivity of the flock whilst minimising selection for anthelmintic resistance to preserve anthelmintic efficacy for the future. Periparturient ewes represent the major source of gastro-intestinal parasites for growing lambs and are therefore a priority for parasite control. This study examines the impact on ewe faecal egg counts (FECs), lamb FECs, lamb daily live weight gains (DLWGs) and pasture larval counts of treating groups of ewes two weeks prior to lambing with either, a long-acting moxidectin treatment, short-acting doramectin or control. Six groups of twenty ewes were allocated to individual paddocks, two groups allocated to each treatment, and weekly faecal sampling was performed throughout from the ewes and from six weeks after the start of lambing in the lambs. Treatment group was found to have a significant effect on both ewe FEC (p<0.001) and lamb FEC (p = 0.001) with the group receiving the long-acting anthelmintic having the lowest ewe and lamb FECs. There was no significant effect on the DLWGs of the lambs. Pasture larval counts at the end of the study period were lowest in the long-acting wormer treatment group. The use of long-acting moxidectin may be helpful as part of a parasite control programme by reducing the worm burdens of ewes and their lambs, decreasing the number of anthelmintic treatments required in that year and by reducing pasture contamination for those sheep which will graze the pasture in the next year. However, like all anthelmintics, its use should be judicious to avoid selection for resistance.


Assuntos
Criação de Animais Domésticos/métodos , Anti-Helmínticos/administração & dosagem , Infecções por Nematoides/veterinária , Doenças dos Ovinos/tratamento farmacológico , Ovinos/parasitologia , Animais , Anti-Helmínticos/farmacocinética , Fazendas , Fezes/parasitologia , Feminino , Meia-Vida , Ivermectina/administração & dosagem , Ivermectina/análogos & derivados , Ivermectina/farmacocinética , Larva , Macrolídeos/administração & dosagem , Macrolídeos/farmacocinética , Nematoides/isolamento & purificação , Infecções por Nematoides/diagnóstico , Infecções por Nematoides/tratamento farmacológico , Infecções por Nematoides/parasitologia , Contagem de Ovos de Parasitas/veterinária , Período Pós-Parto , Gravidez , Doenças dos Ovinos/diagnóstico , Doenças dos Ovinos/parasitologia
6.
Artigo em Chinês | MEDLINE | ID: mdl-32746578

RESUMO

To analyze the clinical data of a case of acute emamectin·chlorfenapyr poisoning in Guangzhou 12th People's Hospital in 2019. The patient developed high fever and night sweats, and gradually became unconscious. The patient died after 5 days of treatment. The toxicity and mortality of emamectin·chlorfenapyr were high. For acute poisoning patients, in addition to conventional symptomatic treatment, early blood purification treatment should be actively carried out.


Assuntos
Dissacarídeos/envenenamento , Inseticidas/envenenamento , Ivermectina/análogos & derivados , Envenenamento/diagnóstico , Piretrinas/envenenamento , Humanos , Ivermectina/envenenamento
7.
Chemosphere ; 261: 127760, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32731029

RESUMO

Predatory mites belonging to family Phytoseiidae (Acari: Mesostigmata) have long been considered as the most promising candidates for biological control of some economically important plant feeding mites and insects. Among them, Euseius scutalis (Athias-Henriot) is one of the most abundant predators and can be considered as an important component for integrated pest management (IPM) programs in Mediterranean citrus orchards. Evaluation of non-target and toxic effects of pesticides is crucial to measure their threats to E. scutalis. In this study, the effects of some selected acaricides (abamectin, etoxazole, spirodiclofen, spirotetramat and pyridaben), that were widely used in citrus orchards, on eggs, larvae, and adult females of E. scutalis were determined under laboratory conditions. In order to observe some possible results at "worst-case scenario", the test units were sprayed at maximum recommended doses. According to the results, abamectin and pyridaben respectively caused 18.00% and 33.50% mortality on eggs, 57.33% and 65.33% on larvae, 23.33% and 44.00% on adult females. While etoxazole was only toxic to the larvae with mortality rates reaching 55.33%, spirodiclofen and spirotetramat were harmless to all developmental stages of the predatory mite. In addition, abamectin, etoxazole and pyridaben caused a significant reduction in the egg production of E. scutalis when compared to the control. Accordingly, spirodiclofen and spirotetramat may be compatible with E. scutalis in IPM programs where it is implemented as a predator. However, further semi-field and/or field experiments are essential in order to draw a final conclusion on compatibility of the other three acaricides.


Assuntos
Acaricidas/toxicidade , Ácaros/efeitos dos fármacos , 4-Butirolactona/análogos & derivados , Animais , Compostos Aza , Citrus/efeitos dos fármacos , Feminino , Ivermectina/análogos & derivados , Larva/efeitos dos fármacos , Controle de Pragas , Praguicidas/farmacologia , Piridazinas , Compostos de Espiro
8.
Aquat Toxicol ; 224: 105519, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32502848

RESUMO

Emamectin benzoate (EB) is a prophylactic pharmaceutical used to protect Atlantic salmon (Salmo salar) smolts migrating out of rivers and into the ocean against sea lice parasites. Randomized control trials comparing the marine survival of smolts treated with EB to a control group is used to calculate the fraction of marine mortality attributable to sea lice parasitism. However, it is assumed that there is no baseline difference in survival induced by the application of EB treatment. We used a combined laboratory and field study approach to investigate the potential impacts of EB treatment on behaviour and survival of hatchery-reared Atlantic salmon in western Norway. In aquaria experiments, EB-treated salmon smolts did not differ significantly in exploratory behaviour. Fish from treated groups responded similarly to simulated predator attack with spontaneous escape and elevated gill beat rate. Three rivers in the Osterfjord system of western Norway were selected for field experiments, Dale, Vosso, and Modalen. Dale River smolts were treated with intraperitoneal EB injections and had lower probability of detection in a wolf trap downstream of the release site than control smolts. Salmon smolts raised in the Vosso River hatchery were treated with EB delivered in their food and were detected on PIT antennas at the rivermouth of Vosso and Modalen at lower rates than control fish, but only when released at downstream sites. Calculation of risk ratios suggested that the bias in mortality caused by treatment with EB decreased the estimated survival of treated fish from an expected 18%to 46%, reducing the observable negative impact of sea lice on Atlantic salmon smolts in randomized control trials. The results suggest that estimates of the fraction of mortality attributable to sea lice may be underestimated due to lower baseline survival of treated fish caused by treatment and bring urgent attention towards a potential systematic underestimation of the impacts of sea lice on wild salmon.


Assuntos
Copépodes/efeitos dos fármacos , Ivermectina/análogos & derivados , Salmo salar/crescimento & desenvolvimento , Poluentes Químicos da Água/toxicidade , Migração Animal/efeitos dos fármacos , Animais , Brânquias/efeitos dos fármacos , Ivermectina/farmacologia , Ivermectina/toxicidade , Modelos Teóricos , Noruega , Distribuição Aleatória , Rios/química , Salmo salar/metabolismo , Análise de Sobrevida , Poluentes Químicos da Água/farmacologia
9.
Aquat Toxicol ; 225: 105528, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32569996

RESUMO

Abamectin (ABM) has been extensively used in Chinese aquaculture systems for parasite control, but no information is available regarding its effects on the important freshwater commercial fish species Schizothorax prenanti. We performed an acute toxicity test to determine the effects of ABM on S. prenanti, and the 48- and 96-h median lethal concentration values were 33.32 and 15.98 µg/L, respectively. In a second test, animals were exposed to sublethal concentrations of ABM (0.5, 2 or 8 µg/L) for 8 days, and various cytological and biochemical parameters were measured. ABM caused DNA damage in hepatocytes, with significant increases in Olive Tail Moment values and 8-hydroxy-2'-deoxyguanosine levels. Hepatocytic apoptosis occurred following all treatments, and was accompanied by an increase in reactive oxygen species (ROS) generation and caspase activity in a dose- and time-dependent manner. In addition, there were significant decreases in glutathione peroxidase levels and superoxide dismutase and catalase activity and increases in malonaldehyde levels. ABM-induced hepatocytic apoptosis in S. prenanti was probably triggered by ROS generation following a cascade reaction of caspases in mitochondrial or death receptor pathways, which caused antioxidant inhibition, oxidative product accumulation, and DNA damage in the liver.


Assuntos
Cyprinidae/metabolismo , Dano ao DNA , Ivermectina/análogos & derivados , Estresse Oxidativo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Antioxidantes/metabolismo , Apoptose/efeitos dos fármacos , Cyprinidae/genética , Cyprinidae/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Água Doce/química , Glutationa Peroxidase/metabolismo , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Hepatócitos/patologia , Ivermectina/toxicidade , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Malondialdeído/metabolismo , Oxirredução , Superóxido Dismutase/metabolismo
10.
Pestic Biochem Physiol ; 165: 104541, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32359561

RESUMO

BACKGROUND: Fluensulfone is a nematicide with a novel mode of action against plant parasitic nematodes. Here, we utilize in vitro hatching assays to investigate fluensufone's ability to inhibit Globodera pallida hatching, relative to the efficacy of other distinct classes of nematicides. RESULTS: Fluensulfone, abamectin, aldicarb and fluopyram inhibit G. pallida hatching from cysts more potently than from isolated eggs. At 1 µM for cysts, the order of potency is fluensulfone> fluopyram> abamectin> aldicarb. At low concentrations of fluensulfone, inhibition of hatching is reversible, however, more than 50% of the juveniles that hatch from cysts pre-treated with fluensulfone have reduced motility. This is observed to a lesser extent with abamectin, fluopyram and aldicarb. When cysts are exposed to higher concentrations of fluensulfone (≥500 µM), abamectin (≥100 µM) and fluopyram (≥50 µM) inhibition of hatching is irreversible. This results from the loss of encysted juvenile structure giving rise to a granulated appearance consistent with necrosis, suggesting a nematicidal effect. Intriguingly, hatching initiated by root diffusate is arrested when egg populations are subsequently exposed to fluensulfone. CONCLUSION: Fluensulfone, abamectin, fluopyram and aldicarb inhibit G. pallida hatching. Fluensulfone is a potent inhibitor of hatching and impacts on the viability of the J2 s emerging from the cysts. This activity, and the previously described impaired motility and metabolism of hatched juveniles, show that fluensulfone's distinct mode of action among existing nematicides intersects at two pivotal steps of the parasitic life cycle.


Assuntos
Aldicarb , Tylenchoidea , Animais , Benzamidas , Ivermectina/análogos & derivados , Piridinas , Sulfonas , Tiazóis
11.
Ecotoxicology ; 29(9): 1486-1499, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32388636

RESUMO

This study evaluated the toxicity of pesticide formulations Kraft® 36 EC (active ingredient-a.i. abamectin) and Score® 250 EC (a.i. difenoconazole), and their mixtures in Daphnia magna at different biological levels of organization. Survival, reproduction and biochemical markers (cholinesterase (ChE), catalase (CAT) and lipid peroxidation (LPO)) were some of the endpoints evaluated. Total proteins and lipids were also studied together with energy consumption (Ec). D. magna neonates were exposed for 96 h to Kraft (2, 4, and 6 ng a.i./L) and Score (12.5, 25, and 50 µg a.i./L) for the biochemical experiments, and for 15 days to abamectin (1-5 ng a.i./L) and to difenoconazole (3.12-50 µg a.i./L) to assess possible changes in reproduction. Exposures of organisms to both single compounds did not cause effects to antioxidant and detoxifying enzymes, except for LPO occurring at the highest concentration of difenoconazole tested. For ChE and CAT there was enzymatic induction in mixture treatments organisms, occurring at minor pesticides concentrations for CAT and at the two highest concentrations for ChE. There were no significant differences for total protein in D. magna but lipids showed an increase at the highest concentrations of pesticide mixture combinations. There was a significant increase of Ec in individuals of all treatments tested. In the chronic test, increased fecundity occurred for D. magna under difenoconazole exposures and mixtures. This study demonstrated that mixtures of these pesticides caused greater toxicity to D. magna than when tested individually, except for Ec. Therefore, effects of mixtures are very hard to predict only based on information from single compounds, which most possibly is the result of biological complexity and redundancy in response pathways, which need further experimentation to become better known.


Assuntos
Daphnia/fisiologia , Dioxolanos/toxicidade , Ivermectina/análogos & derivados , Praguicidas/toxicidade , Triazóis/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Colinesterases , Ivermectina/toxicidade , Reprodução , Testes de Toxicidade Aguda
12.
Toxicol Appl Pharmacol ; 401: 115071, 2020 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-32454055

RESUMO

Prostate Cancer (PCa) is the second most common cancer among men in United States after skin cancer. Conventional chemotherapeutic drugs available for PCa treatment are limited due to toxicity and resistance issues. Therefore, there is an urgent need to develop more effective treatment for advanced PCa. In this current study, we focused on evaluating the anti-cancer efficacy of Eprinomectin (EP), a novel avermectin analog against PC3 metastatic PCa cells. EP displayed robust inhibition of cell viability of PC3 cells in addition to suppressing the colony formation and wound healing capabilities. Our study showed that EP targets PC3 cells via inducing ROS and apoptosis activation. EP treatment enforces cell cycle arrest at G0/G1 phase via targeting cyclin-dependent kinase 4 (CDK4) and subsequent induction of apoptosis in PC3 cells. At the molecular level, EP effectively inhibited the expression of various cancer stem cell markers such as ALDH1, Sox-2, Nanog, Oct3/4 and CD44. Interestingly, EP also inhibited the activity of alkaline phosphatase, a maker of pluripotent stem cells. Of note, EP treatment resulted in the translocation of ß-catenin from the nucleus to the cytoplasm indicating that EP antagonizes Wnt/ß-catenin signaling pathway. Western blotting analysis revealed that EP downregulated the expression of key cell cycle markers such as cyclin D1, cyclin D3, CDK4, and c-Myc. In addition, EP inhibited the anti-apoptotic markers such as Mcl-1, XIAP, c-IAP1 and survivin in PC3 cells. On the other hand, EP treatment resulted in the activation of pH2A.X, Bad, caspase-9, caspase-3 and cleavage of PARP1. Taken together, our data suggests that EP is a potential agent to treat advanced PCa cells via modulating apoptosis signaling.


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Ivermectina/análogos & derivados , Lactonas/farmacologia , Compostos Macrocíclicos/farmacologia , Neoplasias da Próstata/metabolismo , Antineoplásicos/química , Antineoplásicos/uso terapêutico , Apoptose/fisiologia , Citotoxinas/química , Citotoxinas/farmacologia , Citotoxinas/uso terapêutico , Relação Dose-Resposta a Droga , Humanos , Ivermectina/química , Ivermectina/farmacologia , Ivermectina/uso terapêutico , Lactonas/uso terapêutico , Compostos Macrocíclicos/química , Compostos Macrocíclicos/uso terapêutico , Masculino , Células PC-3 , Neoplasias da Próstata/tratamento farmacológico , Espécies Reativas de Oxigênio/antagonistas & inibidores , Espécies Reativas de Oxigênio/metabolismo
13.
Environ Sci Pollut Res Int ; 27(18): 23199-23205, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32333357

RESUMO

Emamectin benzoate (EMB), which is used as a pesticide in agriculture, household, and veterinary medicine, can cause tissue damage with oxidative toxicity and can be considered as inducing apoptosis. In the present study, male mice were conducted by oral administration in EMB doses 25, 50, and 100 (mg/kg/day) for 14 days. Glutathione (GSH) and thiobarbituric acid reactive substance (TBARS) levels using spectrophotometric methods were measured. 8-hydroxy-2'-deoxyguanosine (8-OHdG) which is DNA oxidation biomarker and, stress protein (HSP70) levels, caspase 3 enzyme activities were measured by ELISA techniques. This study shows that in vivo administration of EMB caused a marked induction of oxidative damage in liver tissue as demonstrated by an increased level of TBARS and reduced GSH level. The increase in HSP70 level did not prevent the apoptosis caused by the increase of caspase 3 enzyme activity. Toxicity caused by EMB also showed the formation of genotoxicity with an increase in DNA oxidation biomarker 8-OHdG levels. As a result of the study, the effects of toxicity caused by EMB on lipid; protein; and DNA, structural macromolecules in cells, and the importance of enzymatic and non-enzymatic bonds of the cell's protective systems were determined. Consequently, under experimental conditions, EMB exposure caused toxicity in the liver of male mice, and significant adverse effects were determined with biomarkers.


Assuntos
Agentes de Controle Biológico , Dano ao DNA , Animais , Apoptose , Biomarcadores , DNA , Desoxiguanosina , Glutationa , Ivermectina/análogos & derivados , Fígado , Masculino , Camundongos , Estresse Oxidativo
14.
Pest Manag Sci ; 76(8): 2569-2581, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32237053

RESUMO

BACKGROUND: Milbemectin and abamectin are frequently used to control the spider mite Tetranychus urticae. The development of abamectin resistance in this major pest has become an increasing problem worldwide, potentially compromising the use of milbemectin. In this study, a large collection of European field populations was screened for milbemectin and abamectin resistance, and both target-site and metabolic (cross-)resistance mechanisms were investigated. RESULTS: High to very high levels of abamectin resistance were found in one third of all populations, while milbemectin resistance levels were low for most populations. The occurrence of well-known target-site resistance mutations in glutamate-gated chloride channels (G314D in GluCl1 and G326E in GluCl3) was documented in the most resistant populations. However, a new mutation, I321T in GluCl3, was also uncovered in three resistant populations, while a V327G and L329F mutation was found in GluCl3 of one resistant population. A differential gene-expression analysis revealed the overexpression of detoxification genes, more specifically cytochrome P450 monooxygenase (P450) and UDP-glycosyltransferase (UGT) genes. Multiple UGTs were functionally expressed, and their capability to glycosylate abamectin and milbemectin, was tested and confirmed. CONCLUSIONS: We found a clear correlation between abamectin and milbemectin resistance in European T. urticae populations, but as milbemectin resistance levels were low, the observed cross-resistance is probably not of operational importance. The presence of target-site resistance mutations in GluCl genes was confirmed in most but not all resistant populations. Gene-expression analysis and functional characterization of P450s and UGTs suggests that also metabolic abamectin resistance mechanisms are common in European T. urticae populations. © 2020 Society of Chemical Industry.


Assuntos
Tetranychidae , Animais , Ivermectina/análogos & derivados , Macrolídeos
15.
Pestic Biochem Physiol ; 164: 191-195, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32284126

RESUMO

The γ-aminobutyric acid receptor (GABAR) has been identified as a target site of some commonly used insecticides. Our pervious study documented an interesting phenomenon, i.e. GABA accumulation was involved in abamectin resistance in the carmine spider mite, Tetranychus cinnabarinus. However, the mechanism of this phenomenon remains to be clarified. In this study, we investigated the interaction between abamectin and GABAR. Firstly, an artificial increase of GABA content was conducted in T. cinnabarinus and toxicity assays showed that GABA accumulation could indeed increase the tolerance of T. cinnabarinus to abamectin in vivo. Subsequently a GABAR of T. cinnabarinus, RDL2, was expressed in Xenopus oocytes and its sensitiveness to abamectin was detected. The results revealed that RDL2 showed significant responses to a series of GABA concentrations and GABA inhibited the effect of abamectin in vitro, providing direct evidence of the abamectin resistance mediated by GABA content. Our data confirmed that GABAR is the action target of abamectin and the GABA accumulation is one of the mechanisms of abamectin resistance in spider mites.


Assuntos
Inseticidas , Tetranychidae , Animais , Carmim , Ivermectina/análogos & derivados
16.
Pestic Biochem Physiol ; 164: 196-202, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32284127

RESUMO

Lymantria dispar asiatica is a globally distributed herbivorous pest. Avermectin is a highly effective, broad-spectrum insecticide. In this study, fourth instar L. dispar asiatica larvae were exposed to a LC30 dose of avermectin. The structure and function of larval gut microbial community was analyzed to examine how gut microbiota in L. dispar asiatica larvae responded to avermectin stress. Results showed that the structure and function of gut microbial community in L. dispar asiatica larvae were varied by avermectin stress. To be precise, more than half quantity of the observed Optical Taxonomic Units (OTUs) showed significantly different abundances under avermectin stress. Linear discriminant analysis effect size (LEfSe) suggested nine bacterial genera and 12 fungal genera contributed to the different gut microbial community structure in L. dispar asiatica larvae. Gut microbial function classification (PICRUSt and FUNGuild) suggested that three bacterial function categories and a fungal function guild were significantly increased, and two fungal function guilds were significantly decreased by avermectin stress. This study furthers our understanding of the physiology of L. dispar asiatica larvae under avermectin stress, and is an essential step towards future development of potential pesticide targets.


Assuntos
Inseticidas , Lepidópteros , Mariposas , Animais , Ivermectina/análogos & derivados , Larva
17.
Chemosphere ; 250: 126321, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32135440

RESUMO

The lacewing, Chrysoperla sinica, is an important predatory insect, which plays an important role in the integrated pest management of agroforestry pests. However, the extensive use of insecticides negatively affects C. sinica. The acute toxicity, risk level, and, sublethal effects on growth and production, predation ability, protective enzyme activity and genotoxicity of four insecticides: indoxacarb, emamectin benzoate, imidacloprid and lambda-cyhalothrin to C. sinica were studied. The results showed that all four insecticides had lethal toxicity to larvae of C. sinica. Among them, emamectin benzoate had the highest toxicity with LC50 value of 7.41 mg/L. The insecticides also had different effects on the growth and reproduction of C. sinica, of which lambda-cyhalothrin had the greatest impacts. Even at a very low LC1 concentration (3.37 mg/L), it had strong impacts on the growth, reproduction and predatory ability of C. sinica. The four insecticides also caused a decrease in the predatory ability of the lacewing, of which lambda-cyhalothrin had the greatest effect. During the larval stage, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were significantly decreased by the four insecticides. At the pupal and adult stages, the effects of the four insecticides on the activities of protective enzymes were different, and the activities of SOD, CAT and POD decreased or increased. Indoxacarb and lambda-cyhalothrin exposure induced DNA damage in the haemocytes of C. sinica and produced obvious genotoxicity. These results provide important scientific basis for the rational use of these insecticides and the protection and utilization of lacewing.


Assuntos
Insetos/efeitos dos fármacos , Inseticidas/toxicidade , Animais , Ivermectina/análogos & derivados , Ivermectina/toxicidade , Larva/efeitos dos fármacos , Neonicotinoides/toxicidade , Nitrilos , Nitrocompostos/toxicidade , Oxazinas/toxicidade , Comportamento Predatório/efeitos dos fármacos , Pupa/efeitos dos fármacos , Piretrinas , Testes de Toxicidade Aguda
18.
Environ Toxicol Chem ; 39(4): 863-872, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32181912

RESUMO

It is often difficult to compare studies examining the effects of endectocides on dung fauna because of different experimental approaches, for example, active ingredients (eprinomectin, doramectin, ivermectin, moxidectin) and formulations (injectable, pour-on, spiked). To gain a better understanding, we performed a quantitative meta-analysis using 22 studies to assess the overall effect of endectocide residues on the occurrence (presence or absence) and abundance of aphodiine dung beetles. Our results document a positive effect on the occurrence of adult beetles, indicating that adults tend to be attracted to dung with residues. Conversely, larvae are less likely to occur in the presence of residues. Thus, either adults that colonize dung with residues do not lay eggs or, more likely, the larvae that hatch from these eggs die early in development. Abundance of adult and larval stages was shown to be significantly reduced in dung containing residues. When individual endectocides were compared, only ivermectin demonstrated a significantly negative effect on the abundance of both adults and larvae, possibly owing to a small sample size for other agents. In laboratory studies, only dung "spiked" with endectocides reduced the abundance of larvae, whereas during field research, only pour-on applications were shown to reduce the abundance of larvae. The present study further documents the nontarget effects of endectocide residues on dung-dwelling organisms, provides robust evidence on the consequences of different application methods, and emphasizes the need for standardized methodological techniques in future studies. Environ Toxicol Chem 2020;39:863-872. © 2020 SETAC.


Assuntos
Besouros/efeitos dos fármacos , Resíduos de Drogas/toxicidade , Poluentes Ambientais/toxicidade , Ivermectina/análogos & derivados , Drogas Veterinárias/toxicidade , Animais , Besouros/crescimento & desenvolvimento , Resíduos de Drogas/análise , Poluentes Ambientais/análise , Fezes/química , Ivermectina/análise , Ivermectina/toxicidade , Larva/efeitos dos fármacos , Gado , Drogas Veterinárias/análise
19.
Ecotoxicol Environ Saf ; 194: 110446, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32171122

RESUMO

Pesticides can affect all receiving compartments, especially soils, and their fate and effects may be enhanced by temperature, increasing their risk to ecological functions of soils. In Brazil, the most widely used pesticides are the insecticide Kraft 36 EC® (a.s. abamectin) and the fungicide Score 250 EC® (a.s. difenoconazole), which are commonly used in strawberry, often simultaneously as a mixture. The aim of this study was to evaluate the toxicity of realistic environmental applications, single and in mixtures, for both pesticides to the springtail Folsomia candida and the plant species Allium cepa (onion) and Lycopersicum esculentum (tomato). Mesocosms filled with Brazilian natural soil (lattosolo) were dosed with water (control), Kraft (10.8 g a.s/ha), Score (20 g.a.s/ha) and Kraft + Score (10.8 + 20 g a.s./ha). The applications were repeated every 7 days, during 18 days of experiment, and simulating rainfall twice a week. Collembola reproduction tests were conducted with soils from the first (day 1) and last day (day 18) of experiment for each treatment. Plant toxicity tests were carried out in the experimental units. The experiments were run at 23 °C and 33 °C. Kraft, alone and in the binary mixture, showed high toxicity to the springtails in soils from both days 1 and 18, especially at 23 °C where it caused 100% mortality. Score however, was not toxic to the springtails. Plant growth was reduced by Score, but responses varied depending on temperature. This study indicates a high environmental risk of the insecticide Kraft, particularly at lower temperatures (23 °C), and an influence of temperature on pesticide fate and effects.


Assuntos
Dioxolanos/toxicidade , Ivermectina/análogos & derivados , Poluentes do Solo/toxicidade , Triazóis/toxicidade , Animais , Artrópodes/fisiologia , Brasil , Exposição Ambiental , Fungicidas Industriais , Inseticidas/toxicidade , Ivermectina/toxicidade , Praguicidas/toxicidade , Solo , Temperatura , Testes de Toxicidade
20.
Ecotoxicol Environ Saf ; 194: 110452, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32171961

RESUMO

The commercial farming of Atlantic salmon, Salmo salar, may require the periodic application of emamectin benzoate (EB) treatments to reduce the effects of biological pests, such as sea lice. As a result, EB is detected in sediments beneath these fish farms at considerable levels. Literature sediment toxicity data for EB for marine benthic species is only available for 10-day sediment toxicity tests, which might be too short to assess field effects. Here, we present a sediment toxicity test to determine 28-day mortality and growth effect concentrations for the non-target polychaete worm Arenicola marina, the crustacean Corophium volutator and the mollusk Cerastoderma edule using a marine microcosm setup. Results indicate that no concentration-dependent increase of mortality and growth rate was apparent to A. marina and C. edule. But for C. volutator, a concentration-dependent increase in mortality was observed, resulting in a calculated 28-d LC50 of 316 µg/kg dry sediment (95% confidence interval: 267-373 µg/kg dry sediment). There were significant effects on C. volutator growth rate at concentrations of 100 µg/kg dry sediment and above (NOEC = 30 µg/kg dry sediment). These observations show that C. volutator is more sensitive to EB than A. marina, which differs from results reported in previous studies. Comparison to the most sensitive NOEC (30 µg/kg dry sediment) found for C. volutator (organisms of 8-11 mm length), shows that the Environmental Quality Standard, derived by the Scottish Environment Protection Agency in 2017 which based on freshwater species data (NOEC = 1.175 µg/kg dry sediment), are relatively strict and is sufficiently protective for the marine species tested in this paper.


Assuntos
Ivermectina/análogos & derivados , Poluentes Químicos da Água/toxicidade , Anfípodes/efeitos dos fármacos , Animais , Monitoramento Ambiental/métodos , Água Doce , Sedimentos Geológicos , Ivermectina/toxicidade , Poliquetos , Testes de Toxicidade Crônica
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