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Martín Javier Eguaras - One of the best experts on this subject based on the ideXlab platform.
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susceptibility of varroa destructor acari varroidae to synthetic acaricides in uruguay varroa mites potential to develop acaricide resistance
Parasitology Research, 2011Co-Authors: Matias Maggi, Sergio Roberto Ruffinengo, Yamandu Mendoza, Pilar Ojeda, Gustavo Ramallo, Iganazio Floris, Martín Javier EguarasAbstract:The purpose of this study was to estimate the acaricide susceptibility of Varroa destructor populations from Uruguay, which had never been exposed to synthetic acaricides. It was also to determine whether acaricide resistance to Coumaphos occurred in apiaries in which acaricide rotation had been applied. Bioassays with acaricides against mite populations that had never been exposed to synthetic acaricides were performed, also against mite populations in which control failures with Coumaphos had been reported. Additionally, Coumaphos’ effectiveness in honeybee colonies was experimentally tested. The lethal concentration that kills 50% of the exposed animals (LC50) for susceptible mite populations amounted to 0.15 μg/Petri dish for Coumaphos and to less than 0.3 μg/Petri dish for the other acaricides. Coumaphos LC50 was above 40 μg/Petri dish for resistant mites. The effectiveness of Coumaphos in honeybee colonies parasitized by V. destructor ranged from 17.6% to 93.9%. LC50 for mite populations susceptible to the most commonly applied miticides was determined, and the first case of Coumaphos resistance recorded in Uruguay was established.
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first detection of varroa destructor resistance to Coumaphos in argentina
Experimental and Applied Acarology, 2009Co-Authors: Matias Maggi, Natalia Damiani, Sergio Roberto Ruffinengo, Norma H Sardella, Martín Javier EguarasAbstract:In Argentina, studies on Varroa destructor resistance to Coumaphos are still unknown. At present, high infestation levels of V. destructor are being detected in colonies of Apis mellifera after treatment with this acaricide. The aim of the present study was to determine the LC50 of Coumaphos in V. destructor from four apiaries with high mite density after treatment with Coumaphos. The LC50’s were 112, 319, 127 and 133 μg/Petri dish for mites from the four apiaries. Significant LC50 differences were detected between resistant and susceptible mites. LC50 increased 197–559-fold when compared to the corresponding baseline, suggesting the development of resistance. These results are the first report of resistance to Coumaphos in V. destructor in Argentina.
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lc50 baseline levels of amitraz Coumaphos fluvalinate and flumethrin in populations of varroa destructor from buenos aires province argentina
Journal of Apicultural Research, 2008Co-Authors: Matias Maggi, Martín Javier Eguaras, Sergio Roberto Ruffinengo, Liesel B. Gende, Norma H SardellaAbstract:SummaryThis study estimates the LC50 baseline levels for amitraz, Coumaphos, fluvalinate, and flumethrin in susceptible Varroa destructor populations in Argentina. Concentration response bioassays were conducted with each acaricide. Laboratory results of lethal concentrations (LC50) were: 0.1 μg/dish for amitraz; 0.29 μg/dish for fluvalinate; 0.34 μg/dish for flumethrin; and 0.57 μg/dish for Coumaphos, respectively. All tests guaranteed 100 % bee survival. LC50 references for mite populations susceptible to the most commonly used acaricides were thus established for Argentina, which will aid the establishment of integrated pest management programmes for V. destructor.
Matias Maggi - One of the best experts on this subject based on the ideXlab platform.
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susceptibility of varroa destructor acari varroidae to synthetic acaricides in uruguay varroa mites potential to develop acaricide resistance
Parasitology Research, 2011Co-Authors: Matias Maggi, Sergio Roberto Ruffinengo, Yamandu Mendoza, Pilar Ojeda, Gustavo Ramallo, Iganazio Floris, Martín Javier EguarasAbstract:The purpose of this study was to estimate the acaricide susceptibility of Varroa destructor populations from Uruguay, which had never been exposed to synthetic acaricides. It was also to determine whether acaricide resistance to Coumaphos occurred in apiaries in which acaricide rotation had been applied. Bioassays with acaricides against mite populations that had never been exposed to synthetic acaricides were performed, also against mite populations in which control failures with Coumaphos had been reported. Additionally, Coumaphos’ effectiveness in honeybee colonies was experimentally tested. The lethal concentration that kills 50% of the exposed animals (LC50) for susceptible mite populations amounted to 0.15 μg/Petri dish for Coumaphos and to less than 0.3 μg/Petri dish for the other acaricides. Coumaphos LC50 was above 40 μg/Petri dish for resistant mites. The effectiveness of Coumaphos in honeybee colonies parasitized by V. destructor ranged from 17.6% to 93.9%. LC50 for mite populations susceptible to the most commonly applied miticides was determined, and the first case of Coumaphos resistance recorded in Uruguay was established.
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first detection of varroa destructor resistance to Coumaphos in argentina
Experimental and Applied Acarology, 2009Co-Authors: Matias Maggi, Natalia Damiani, Sergio Roberto Ruffinengo, Norma H Sardella, Martín Javier EguarasAbstract:In Argentina, studies on Varroa destructor resistance to Coumaphos are still unknown. At present, high infestation levels of V. destructor are being detected in colonies of Apis mellifera after treatment with this acaricide. The aim of the present study was to determine the LC50 of Coumaphos in V. destructor from four apiaries with high mite density after treatment with Coumaphos. The LC50’s were 112, 319, 127 and 133 μg/Petri dish for mites from the four apiaries. Significant LC50 differences were detected between resistant and susceptible mites. LC50 increased 197–559-fold when compared to the corresponding baseline, suggesting the development of resistance. These results are the first report of resistance to Coumaphos in V. destructor in Argentina.
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lc50 baseline levels of amitraz Coumaphos fluvalinate and flumethrin in populations of varroa destructor from buenos aires province argentina
Journal of Apicultural Research, 2008Co-Authors: Matias Maggi, Martín Javier Eguaras, Sergio Roberto Ruffinengo, Liesel B. Gende, Norma H SardellaAbstract:SummaryThis study estimates the LC50 baseline levels for amitraz, Coumaphos, fluvalinate, and flumethrin in susceptible Varroa destructor populations in Argentina. Concentration response bioassays were conducted with each acaricide. Laboratory results of lethal concentrations (LC50) were: 0.1 μg/dish for amitraz; 0.29 μg/dish for fluvalinate; 0.34 μg/dish for flumethrin; and 0.57 μg/dish for Coumaphos, respectively. All tests guaranteed 100 % bee survival. LC50 references for mite populations susceptible to the most commonly used acaricides were thus established for Argentina, which will aid the establishment of integrated pest management programmes for V. destructor.
Sergio Roberto Ruffinengo - One of the best experts on this subject based on the ideXlab platform.
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susceptibility of varroa destructor acari varroidae to synthetic acaricides in uruguay varroa mites potential to develop acaricide resistance
Parasitology Research, 2011Co-Authors: Matias Maggi, Sergio Roberto Ruffinengo, Yamandu Mendoza, Pilar Ojeda, Gustavo Ramallo, Iganazio Floris, Martín Javier EguarasAbstract:The purpose of this study was to estimate the acaricide susceptibility of Varroa destructor populations from Uruguay, which had never been exposed to synthetic acaricides. It was also to determine whether acaricide resistance to Coumaphos occurred in apiaries in which acaricide rotation had been applied. Bioassays with acaricides against mite populations that had never been exposed to synthetic acaricides were performed, also against mite populations in which control failures with Coumaphos had been reported. Additionally, Coumaphos’ effectiveness in honeybee colonies was experimentally tested. The lethal concentration that kills 50% of the exposed animals (LC50) for susceptible mite populations amounted to 0.15 μg/Petri dish for Coumaphos and to less than 0.3 μg/Petri dish for the other acaricides. Coumaphos LC50 was above 40 μg/Petri dish for resistant mites. The effectiveness of Coumaphos in honeybee colonies parasitized by V. destructor ranged from 17.6% to 93.9%. LC50 for mite populations susceptible to the most commonly applied miticides was determined, and the first case of Coumaphos resistance recorded in Uruguay was established.
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first detection of varroa destructor resistance to Coumaphos in argentina
Experimental and Applied Acarology, 2009Co-Authors: Matias Maggi, Natalia Damiani, Sergio Roberto Ruffinengo, Norma H Sardella, Martín Javier EguarasAbstract:In Argentina, studies on Varroa destructor resistance to Coumaphos are still unknown. At present, high infestation levels of V. destructor are being detected in colonies of Apis mellifera after treatment with this acaricide. The aim of the present study was to determine the LC50 of Coumaphos in V. destructor from four apiaries with high mite density after treatment with Coumaphos. The LC50’s were 112, 319, 127 and 133 μg/Petri dish for mites from the four apiaries. Significant LC50 differences were detected between resistant and susceptible mites. LC50 increased 197–559-fold when compared to the corresponding baseline, suggesting the development of resistance. These results are the first report of resistance to Coumaphos in V. destructor in Argentina.
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lc50 baseline levels of amitraz Coumaphos fluvalinate and flumethrin in populations of varroa destructor from buenos aires province argentina
Journal of Apicultural Research, 2008Co-Authors: Matias Maggi, Martín Javier Eguaras, Sergio Roberto Ruffinengo, Liesel B. Gende, Norma H SardellaAbstract:SummaryThis study estimates the LC50 baseline levels for amitraz, Coumaphos, fluvalinate, and flumethrin in susceptible Varroa destructor populations in Argentina. Concentration response bioassays were conducted with each acaricide. Laboratory results of lethal concentrations (LC50) were: 0.1 μg/dish for amitraz; 0.29 μg/dish for fluvalinate; 0.34 μg/dish for flumethrin; and 0.57 μg/dish for Coumaphos, respectively. All tests guaranteed 100 % bee survival. LC50 references for mite populations susceptible to the most commonly used acaricides were thus established for Argentina, which will aid the establishment of integrated pest management programmes for V. destructor.
John E. George - One of the best experts on this subject based on the ideXlab platform.
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first report of fipronil resistance in rhipicephalus boophilus microplus of mexico
Veterinary Parasitology, 2013Co-Authors: Robert J Miller, Ronald B. Davey, John E. George, Consuelo Almazan, Martin Ortizestrada, Adalberto Perez A De LeonAbstract:Abstract Five strains of Rhipicephalus (Boophilus) microplus collected from Tamaulipas Mexico were tested for resistance against several classes of acaricides commonly used. All were resistant to fipronil. Four of five were co-resistant to permethrin and Coumaphos in addition to being resistant to fipronil. One strain, El Zamora was found multi-resistant to permethrin, Coumaphos, fipronil, and amitraz. Selection with fipronil for 3 generations produced a resistance ratio of 8.3 and 9.4 at the LC50 and the LC99 estimates, respectively. Permethrin resistance in El Zamora was possibly linked to elevated esterase (CZEST9) and could be a contributing factor of resistance to fipronil. The implications of resistance for the control of the southern cattle tick in the future are discussed.
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Effect of Rainfall Exposure Immediately After a Single Dip Treatment with Coumaphos on the Control of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) on Infested Cattle
Journal of Medical Entomology, 2009Co-Authors: Ronald B. Davey, Robert J Miller, J. Allen Miller, John E. GeorgeAbstract:Efficacy of a single dip treatment in Coumaphos at 0.182% active ingredient was determined against all parasitic stages of Rhipicephalus (Boophilus) microplus (Canestrini) on infested cattle exposed to various levels of rainfall immediately after treatment. One group of calves remained untreated with no exposure to rainfall to serve as a negative control. A second group of cattle treated with Coumaphos, but not exposed to rainfall, acted as a positive treated control. Three additional groups of Coumaphos-treated cattle were exposed to 14.3, 28.6, and 42.9 mm of rainfall, respectively. In the Coumaphos-treated group not exposed to a rainfall, overall mean control (99.2%) was greater and mean female engorgement weight (200 mg), egg mass weight (43 mg), and index of fecundity (IF; 2.90) were all less than any group exposed to rainfall. Although exposure to the lowest level of rainfall (14.3 mm) resulted in substantially greater control (83.7%) with lower mean egg mass weight (65 mg) and IF (62.26) than ticks exposed to 28.6 or 42.9 mm of rainfall, differences were seldom significant (P > 0.05). This suggested that higher levels of rainfall exposure adversely impacted Coumaphos efficacy somewhat more than lower levels of rainfall exposure. Control remained >97% against larval ticks regardless of rainfall exposure level; however, against nymphs or adults, dramatic declines in control occurred as a result of exposure to any rainfall. Thus, the movement of Coumaphos treated cattle exposed to any level of rainfall would pose a high risk of dispersing viable ticks into uninfested areas.
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Differential response to diazinon and Coumaphos in a strain of Boophilus microplus (Acari: Ixodidae) collected in Mexico.
Journal of Medical Entomology, 2008Co-Authors: Robert J Miller, Ronald B. Davey, Mary Tijerina, John E. GeorgeAbstract:Abstract Boophilus microplus, collected from Nuevo Leon, Mexico, were found to be highly resistant to diazinon but not highly resistant to Coumaphos, suggesting that different mechanisms of resistance were present in these ticks than other Mexican organophosphate (OP)-resistant ticks reported previously. When exposed to Coumaphos and piperonyl butoxide or triphenylphosphate, the LC50 estimate was reduced by 3.5- and 6.3-fold, respectively, suggesting that mono-oxygenases and/or esterases were involved in resistance to Coumaphos. Additionally, it was determined that this strain had an Acetylycholinesterase (AChe) that was insensitive to the active form of Coumaphos, coroxon, taking at least 24 min longer to reach 50% reduction in AChE activity compared with the susceptible strain. When exposed to diazinon, none of the synergists tested significantly lowered the LC50. However, it was determined that it took six times longer to reach 60% inhibition of AChE in the resistant strain compared with the susceptibl...
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Toxicological and biochemical characterization of Coumaphos resistance in the San Roman strain of Boophilus microplus (Acari: Ixodidae)
Pesticide Biochemistry and Physiology, 2005Co-Authors: John H. Pruett, Ronald B. Davey, John E. GeorgeAbstract:The San Roman strain of the southern cattle tick, Boophilus microplus, collected from Mexico was previously reported to have a high level of resistance to the organophosphate acaricide Coumaphos. An oxidative detoxification mechanism was suspected to contribute to Coumaphos resistance in this tick strain, as Coumaphos bioassay with piperonyl butoxide (PBO) on larvae of this resistant strain resulted in enhanced Coumaphos toxicity, while Coumaphos assays with PBO resulted in reduced toxicity of Coumaphos in a susceptible reference strain. In this study, we further analyzed the mechanism of oxidative metabolic detoxification with synergist bioassays of coroxon, the toxic metabolite of Coumaphos, and the mechanism of target-site insensitivity with acetylcholinesterase (AChE) inhibition kinetics assays. Bioassays of coroxon with PBO resulted in synergism of coroxon toxicity in both the San Roman and the susceptible reference strains. The synergism ratio of PBO on coroxon in the resistant strain was 4.5 times that of the susceptible strain. The results suggested that the cytP450-based metabolic detoxification existed in both resistant and susceptible strains, but its activity was significantly enhanced in the resistant strain. Comparisons of AChE activity and inhibition kinetics by coroxon in both susceptible and resistant strains revealed that the resistant San Roman strain had an insensitive AChE, with a reduced phosphorylation rate, resulting in a reduced bimolecular reaction constant. These data indicate a mechanism of Coumaphos resistance in the San Roman strain that involves both insensitive AChE and enhanced cytP450-based metabolic detoxification.
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resistance to Coumaphos and diazinon in boophilus microplus acari ixodidae and evidence for the involvement of an oxidative detoxification mechanism
Journal of Medical Entomology, 2003Co-Authors: Andrew Y Li, Ronald B. Davey, Robert J Miller, John E. GeorgeAbstract:The levels of resistance to two organophosphate acaricides, Coumaphos and diazinon, in several Mexican strains of Boophilus microplus (Canestrini) were evaluated using the FAO larval packet test. Regression analysis of LC50 data revealed a signiÞcant cross-resistance pattern between those two acaricides. Metabolic mechanisms of resistance were investigated with synergist bioassays. Piperonyl butoxide (PBO) reduced Coumaphos toxicity in susceptible strains, but synergized cou- maphos toxicity in resistant strains. There was a signiÞcant correlation between PBO synergism ratios and the Coumaphos resistance ratios. The results suggest that an enhanced cytochrome P450 mono- oxygenase (cytP450)-mediated detoxiÞcation mechanism may exist in the resistant strains, in addition to the cytP450-mediated metabolic pathway that activates Coumaphos. PBO failed to synergize diazinon toxicity in resistant strains, suggesting the cytP450 involved in detoxiÞcation were speciÞc. Triphenylphosphate (TPP) synergized toxicity of both acaricides in both susceptible and resistant strains, and there was no correlation between TPP synergism ratios and the LC50 estimates for either acaricide. Esterases may not play a major role in resistance to Coumaphos and diazinon in those strains. Bioassays with diethyl maleate (DEM) revealed a signiÞcant correlation between DEM synergism ratios and LC50 estimates for diazinon, suggesting a possible role for glutathione S-transferases in diazinon detoxiÞcation. Resistance to Coumaphos in the Mexican strains of B. microplus was likely to be conferred by both acytP450-mediated detoxiÞcation mechanism described here and the mechanism of insensitive acetylcholinesterases reported elsewhere. The results of this study also underscore the potential risk of Coumaphos resistance in B. microplus from Mexico to the U.S. cattle fever tick eradication program.
S Bogdanov - One of the best experts on this subject based on the ideXlab platform.
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study of acaricide stability in honey characterization of amitraz degradation products in honey and beeswax
Journal of Agricultural and Food Chemistry, 2001Co-Authors: E Korta, Amin El-bakkali, V Kilchenmann, L A Berrueta, B Gallo, F. Vicente, S BogdanovAbstract:A study on the possible degradation of amitraz, bromopropylate, Coumaphos, chlordimeform, cymiazole, flumethrin, and tau-fluvalinate during the storage of honey was carried out by HPLC. Except amitraz, the other acaricides are stable in this medium for at least 9 months. Degradation studies of amitraz in honey and beeswax were carried out; the degradation products detected in both matrices were 2,4-dimethylphenylformamide (DMF) and N-(2,4-dimethylphenyl)-N‘-methylformamidine (DPMF). The reaction rate constants and the half-lives of the amitraz degradation in honey and wax were calculated. Amitraz was nearly completely degraded within 1 day in beeswax and within 10 days in honey. When amitraz-spiked combs are recycled into new beeswax, DMF was found to be the principal degradation product left in pure wax. Keywords: Acaricide residues; amitraz; bromopropylate; cymiazole; Coumaphos; chlordimeform; tau-fluvalinate; flumethrin; degradation products; kinetics; honey; beeswax
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study of the degradation products of bromopropylate chlordimeform Coumaphos cymiazole flumethrin and tau fluvalinate in aqueous media
Talanta, 2000Co-Authors: E Corta, Amin El-bakkali, Alejandro Barranco, L A Berrueta, B Gallo, F. Vicente, S BogdanovAbstract:Abstract Degradation processes of bromopropylate, Coumaphos, chlordimeform, cymiazole, flumethrin and fluvalinate in aqueous media have been studied by HPLC. Cymiazole is stable at any tested pH (1–11), while bromopropylate, flumethrin and Coumaphos are unstable at basic pH and chlordimeform and fluvalinate in neutral and basic media. The main degradation products have been identified by GC-MS. The reaction rate constants and half-lives were calculated and the effect of co-solvents on the rate and product profile was studied.
