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Avalia??o in vitro de uma cepa de campo de Boophilus microplus (Acari : Ixodidae) resistente à amitraz
Santamaría Vargas, Minerva;Soberanes Céspedes, Noé;Fragoso Sánchez, Hugo;Martins, Jo?o Ricardo;Cordovés Céspedes, Carlos Octávio;
Ciência Rural , 2003, DOI: 10.1590/S0103-84782003000400024
Abstract: the use of chemical acaricide still remains as the main tool against the cattle tick boophilus microplus. in southern brazil, amitraz applied by immersion and/or spray is the main active ingredient to control organophosphate and synthetic pyrethroid resistant strains. in consequence it is important to conduct investigations in order to prolong useful life of this ingredient. in this article, toxicological behaviour of a strain of boophilus microplus named "santa luiza" collected in the locality of alegrete, state of rio grande do sul, brazil, was analyzed against acaricides organophosphorous, pyrethroids, mixtures sp and op and amitraz. results showed factors of resistance from 2.3 to 3.95 to op, 23.3 to 147.56 to sp and 3.76 to 21.57 to amitraz indicating that this strain showed multiple resistance to tested acaricides. characterization and purification of a b. microplus strain resistant to amitraz will allow its use as a reference strain for future utilization in biological evaluation of alternative acaricides as well as to standard and to validate diagnostic methods to detect resistant to this acaricide.
Acaricide resistance mechanisms in Rhipicephalus (Boophilus) microplus
Guerrero, Felix David;Lovis, Léonore;Martins, Jo?o Ricardo;
Revista Brasileira de Parasitologia Veterinária , 2012, DOI: 10.1590/S1984-29612012000100002
Abstract: acaricide resistance has become widespread in countries where cattle ticks, rhipicephalus (boophilus) microplus, are a problem. resistance arises through genetic changes in a cattle tick population that causes modifications to the target site, increased metabolism or sequestration of the acaricide, or reduced ability of the acaricide to penetrate through the outer protective layers of the tick’s body. we review the molecular and biochemical mechanisms of acaricide resistance that have been shown to be functional in r. (b.) microplus. from a mechanistic point of view, resistance to pyrethroids has been characterized to a greater degree than any other acaricide class. although a great deal of research has gone into discovery of the mechanisms that cause organophosphate resistance, very little is defined at the molecular level and organophosphate resistance seems to be maintained through a complex and multifactorial process. the resistance mechanisms for other acaricides are less well understood. the target sites of fipronil and the macrocyclic lactones are known and resistance mechanism studies are in the early stages. the target site of amitraz has not been definitively identified and this is hampering mechanistic studies on this acaricide.
Resistencia de la garrapata Boophilus microplus a los ixodicidas Ixodicide resistance of the the Boophilus microplus tick to ixodicides  [cached]
M A Alonso-Díaz,R I Rodríguez-Vivas,H Fragoso-Sánchez,R Rosario-Cruz
Archivos de medicina veterinaria , 2006,
Abstract: La resistencia de las garrapatas a los ixodicidas es uno de los principales problemas que afectan a los productores bovinos en el subtrópico y trópico, donde las garrapatas, especialmente Boophilus microplus y los agentes que transmiten, tienen un efecto costo-beneficio en la producción. El objetivo de la presente revisión es dar a conocer los principales hallazgos de la resistencia de B. microplus. Se presenta la definición, desarrollo, evolución y el diagnóstico de la resistencia. Asimismo, se presenta la distribución mundial de la resistencia de las garrapatas, especialmente en México. Se concluye que la resistencia de las garrapatas a los ixodicidas es un problema importante en la producción bovina y se necesitan implementar medidas estratégicas para reducir o retardar el impacto en la ganadería bovina. The tick is a major problem for cattle producers in subtropical and tropical areas where ticks, especially Boophilus microplus, and the disease agents that they transmit, are a constraint to cost-effective production. The aim of the present review is to present the most important findings of acaricide resistance in the B. microplus tick. The definition, development, evolution and diagnosis of tick resistance are presented. The distribution of tick resistance in the world, especially in Mexico is also presented. It is concluded that tick resistance is an important problem for cattle production and strategies need to be developed to reduce the impact on cattle.
Levels of natural resistance to Boophilus microplus (Acari: Ixodidae) in Carora breed bulls
Meléndez,Roy D.; Coronado,Alfredo; Mujica,Franklin; Cerutti,Franco; Mosquera,Ortelio;
Revista de Biología Tropical , 1998,
Abstract: boophilus microplus infestation is one of the most serious limitations to cattle industry in tropical regions, even though bovines show natural resistance to ticks. this resistance was evaluated in cross-bred carora bulls (ccb) a tropicalized dairy breed from venezuela. seven ccb were experimentally infested with b. microplus larvae, "mozo" strain, they were considered tick-naive because they had never been infested with ticks. the mean inoculum size applied on each bull was 6 477 larvae. after life cycle was completed adult female body weight (bw), egg mass weight (ew), egg hatching rate (%eh), and reproductive index (ri) were recorded. results revealed a high variability in the levels of resistance to b. microplus. thus, one animal showed greater resistance (dunnett, p< 0.05) for the analyzed parameters in contrast with three non-resistant bulls. the others had moderate resistance. the trait "resistance" should be included togheter with other traits often used in genetic selection of cattle.
Levels of natural resistance to Boophilus microplus (Acari: Ixodidae) in Carora breed bulls  [cached]
Roy D. Meléndez,Alfredo Coronado,Franklin Mujica,Franco Cerutti
Revista de Biología Tropical , 1998,
Abstract: Boophilus microplus infestation is one of the most serious limitations to cattle industry in tropical regions, even though bovines show natural resistance to ticks. This resistance was evaluated in Cross-bred Carora Bulls (CCB) a tropicalized dairy breed from Venezuela. Seven CCB were experimentally infested with B. microplus larvae, "Mozo" strain, they were considered tick-naive because they had never been infested with ticks. The mean inoculum size applied on each bull was 6 477 larvae. After life cycle was completed adult female body weight (BW), egg mass weight (EW), egg hatching rate (%EH), and reproductive index (RI) were recorded. Results revealed a high variability in the levels of resistance to B. microplus. Thus, one animal showed greater resistance (Dunnett, p< 0.05) for the analyzed parameters in contrast with three non-resistant bulls. The others had moderate resistance. The trait "resistance" should be included togheter with other traits often used in genetic selection of cattle.
Resistance to cypermethrin and amitraz in Rhipicephalus (Boophilus) microplus on the Santa Catarina Plateau, Brazil Situa o da resistência do Rhipicephalus (Boophilus) microplus à cipermetrina e amitraz no Planalto Catarinense, Brasil  [cached]
Luana Paula Haubold Neis Veiga,Antonio Pereira de Souza,Valdomiro Bellato,Amélia Aparecida Sartor
Revista Brasileira de Parasitologia Veterinária , 2012, DOI: 10.1590/s1984-29612012000200011
Abstract: With the objective of evaluating Rhipicephalus (Boophilus) microplus resistance to cipermetrina and amitraz, were collected engorged tick females from cattle on 20 farms on the Santa Catarina Plateau, in southern Brazil, between January of 2004 and May of 2006. Were also received 20 groups of engorged R. (B.) microplus females, collected by cattle farmers requesting acaricidal efficacy (AE) testing. Were performed in vitro tests, which consisted of immersing engorged females in cypermethrin (0.015%) and in amitraz (0.025%). An AE >95% was considered indicative of effectiveness. Of the 20 collected groups, 18 (90%) showed cypermethrin resistance and 1 (5%) showed amitraz resistance. Of the 20 received groups, 19 (95%) showed cypermethrin resistance and 2 (10%) showed amitraz resistance. The AE of cypermethrin was found to be >95%, 85-94%, and 55-64%, respectively, in 4 (57.1%), 2 (28.6%), and 1 (14.3%) of 7 reference groups, collected in the 1997-2001 period. The AE of amitraz was >95% in all of those groups. Among the groups of specimens received for analysis in that period, the AE of amitraz was >95% in 6 (85.71%) and 75-84% in 1 (14.28%). R. (B.) microplus resistance to acaricides is increasing on the Santa Catarina Plateau. Com os objetivos de avaliar a resistência do Rhipicephalus (Boophilus) microplus à cipermetrina e ao amitraz no Planalto Catarinense, no período de janeiro de 2004 a maio de 2006, foram coletadas teleóginas em bovinos de 20 propriedades onde os produtores autorizaram a coleta (amostras por conveniência) e recebidas teleóginas de mais 20 propriedades com objetivo de diagnóstico de eficácia. Os testes in vitro foram realizados por imers o de teleóginas em cipermetrina (0,015%) e amitraz (0,025%). Considerando a eficácia igual ou superior a 95%, das 20 propriedades amostradas, 18 (90%) apresentaram resistência à cipermetrina e uma (5%) ao amitraz. Das 20 propriedades com teleóginas para diagnóstico, 19 (95%) apresentaram resistência à cipermetrina e duas (10%) ao amitraz. No período de agosto de 1997 a dezembro de 2001, das sete amostras coletadas, em quatro (57,1%) a eficácia da cipermetrina foi >95%, em duas (28,6%) entre 85% e 94% e em uma, (14,3%) entre 55% e 64%. A eficácia do amitraz foi >95%, em teleóginas de todas as propriedades. Nas amostras para diagnóstico, seis (85,71%) apresentaram eficácia para o amitraz >95% e uma (14,28%) entre 75% e 84%. A resistência desse ixodídeo aos carrapaticidas testados é crescente no Planalto Catarinense.
Acaricide resistance of Rhipicephalus (Boophilus) microplus in State of Mato Grosso do Sul, Brazil
Andreotti, Renato;Guerrero, Felix David;Soares, Mariana Aparecida;Barros, Jacqueline Cavalcante;Miller, Robert John;Léon, Adalberto Pérez de;
Revista Brasileira de Parasitologia Veterinária , 2011, DOI: 10.1590/S1984-29612011000200007
Abstract: this study was conducted to obtain an epidemiological view of acaricide resistance in populations of rhipicephalus (boophilus) microplus in the state of mato grosso do sul. twenty-four tick samples were collected from municipalities in the state where farmers had reported concerns about resistance to or failure of tick control. these ticks were subjected to in vitro resistance detection assays using the adult immersion test (ait). the efficacy of alpha-cypermethrin, cypermethrin and amitraz treatments on samples collected throughout the state was generally poor. ait showed efficacy > 90% from the use of ddvp + chlorfenvinphos) (20 out of 21 municipalities), dichlorvos + cypermethrin (10 out of 16 municipalities) and cypermethrin + citronella + chlorpyrifos + piperonyl butoxide (20 out of 21 municipalities). pcr assays were used to detect the presence of pyrethroid resistance-associated sodium channel gene mutation. larvae from three different populations that had previously been diagnosed as pyrethroid-resistant, through ait, were evaluated. the pcr assays showed that the pyrethroid resistance-associated gene mutation was absent from these three populations. this study confirms that the emergence of resistance is a constant challenge for the livestock industry, and that development of resistance continues to be a major driver for new antiparasitic drugs to be developed.
Detección de resistencia a los acaricidas en la garrapata del ganado Boophilus microplus mediante análisis de zimogramas (Acaricide resistance detection in the cattle tick Boophilus microplus by zymograms analysis).  [PDF]
Miranda, Miranda, Estefan,Osorio, Miranda Jorge,Cossío, Bayúgar, Raquel
REDVET , 2005,
Abstract: La identificación de resistencia a los productos acaricidas en la garrapata B. microplus, se hace mediante un complicado bioensayo, que requiere garrapatas de referencia y de campo cultivadas sobre bovinos vivos y restringidos durante semanas. Con el fin de evaluar una posible alternativa diagnóstica, se hicieron ensayos enzimáticos en geles de poliacrilamida-SDS, usando extractos de larvas de garrapatas provenientes de cuatro cepas de referencia con diferentes niveles de resistencia y susceptibilidad a productos acaricidas. Los ensayos que se dise aron para detectar las enzimas esterasa, fosfodiesterasa, glutatión peroxidasa y catalasa, fueron procesados como zimogramas en imágenes digitalizadas, a partir de las cuales se obtuvieron sus respectivos densitogramas, valorando las movilidades electroforéticas relativas (Rf), así como las diferentes masas moleculares (MM) en miles de Daltons (kDa) y actividades enzimáticas específicas (AEE). Se identificó una elevada actividad de esterasa en posición Rf 0.52 con una MM de 47 kDa en las cepas resistentes, con un incremento en AEE del 317 % cuando se compara con las garrapatas susceptibles a los acaricidas. También se identificó una fosfodiesterasa en Rf. 0.1 con MM de 130 kDa presente en las cepas resistentes, con un incremento de AEE del 340% con respecto al nivel basal de la cepa susceptible. Se concluyó que estos ensayos enzimáticos pueden ser utilizados como indicadores de resistencia a los acaricidas en poblaciones de garrapatas aisladas de campo, constituyendo un procedimiento rápido, eficaz y económico, como alternativa al complicado bioensayo actualmente utilizado. Acaricide resistance detection in the cattle tick Boophilus microplus, is achieved by a complex bioassay which requires reference strains of ticks as well as field isolated ticks, cultured on living cattle restrained for weeks. In order to assess an alternate diagnostics procedure, enzymatic assays were performed on SDS polyacrylamide gels, using tick extracts from four reference strains with variable levels of resistance and susceptibility to acaricide products. Enzyme assays were designed for detection of esterase, phosphodiesterase, glutathion peroxidase and catalase. Zymograms were processed as digital images obtaining their respective densitograms as well as Relative Electrophoretic Motility (Rf.), Molecular Mass(MM) in thousands of Daltons (kDa), as well as Enzyme Specific Activity (ESA). An increase in esterase activity was located at Rf. 0.52 with a MM of 47 kDa in all resistant strains with an increment of 317% when compared to th
Tripanosomatides like Trypanosoma theileri in the cattle tick Boophilus microplus
Martins, Jo?o Ricardo;Leite, Romário C.;Doyle, Rovaina L.;
Revista Brasileira de Parasitologia Veterinária , 2008, DOI: 10.1590/S1984-29612008000200010
Abstract: findings of epimastigotes forms of a tripanosomatide is reported in the hemolymph of the cattle tick boophilus microplus in the state of rio grande do sul, southern brazil. morphological evidences suggest they are similar to trypanosoma theileri, a species described as non pathogenic to cattle, and usually transmitted by tabanids.
Boophilus microplus Pyrethroid Resistance Associated to Increased Levels of Monooxygenase Enzymatic Activity in Field Isolated Mexican Ticks  [PDF]
Raquel Cossio-Bayugar,Estefan Miranda-Miranda,Alejandrina Ortiz-Najera,Salvador Neri-Orantes
Journal of Biological Sciences , 2008,
Abstract: This study was made to assess SDS-PAGE monooxygenases zymograms in the presence of synthetic monooxygenase enzyme substrates, in order to establish a reliable methodology to measure monooxygenase activity levels on acaricide resistant ticks and finding a probable association between monooxygenase enzymatic levels and B. microplus acaricide resistance. Monooxygenase activity was found in the zymograms of the analyzed ticks at three polypeptidic bands of 147, 125 and 98 kDa, densitometric measurements of monooxygenases zymograms at these specific enzymatic bands showed a statistically significant monooxygenase activity increase (p<0.001 unpaired t-test) on Pyrethroid resistant ticks when compared to the same bands in the acaricide susceptible reference ticks. Present results showed that monooxygenase zymograms combined with densitographic analysis, are useful as an acaricide resistance detection test and suggest a linkage between increased monooxygenase activities and Pyrethroid acaricide resistance in B. microplus.
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