Análise in vitro da efcácia do amitraz sobre populaÇões de Rhipicephalus (Boophilus) microplus (Canestrini, 1887) da região sul do Rio Grande do Sul

Santos, Tânia Regina Bettin dos; Pappen, Felipe Geraldo; Farias, Nara Amélia da Rosa; Vaz, Itabajara da Silva

doi:10.4322/rbpv.018e1010

Cited by 8 publications

(4 citation statements)

References 6 publications

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“…;OLIVEIRA, 2005;ANDREOTTI et al, 2011;VEIGA et al, 2012). In the state of Rio Grande do Sul, several cases of resistance have been reported (VARGAS et al, 2003;CAMILLO et al, 2009;SANTOS et al, 2009). Reduced in vitro efficacy of amitraz against R.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of three larval bioassays to evaluate susceptibility of Rhipicephalus (Boophilus) microplus to amitraz

Santos

Klafke²,

Pappen

et al. 2013

Rev. Bras. Parasitol. Vet.

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Field samples of Rhipicephalus (Boophilus) microplus from the state of Rio Grande do Sul, Brazil, were assessed using the following methods: larval packet test (LPT), larval immersion test (LIT) and syringe immersion test (SIT). The following parameters were determined for each population and for the Mozo susceptible reference strain: lethal concentration for 50% (LC 50 ) with its 95% confidence interval (95% CI), regression line slope and resistance ratio (RR). Using the LPT, only one population was susceptible to amitraz, presenting a RR of 1.9. Using the same technique, the other populations presented RRs of between 92.9 and 3445.8 and were considered resistant. The LC 50 of the Mozo strain calculated using the LPT, LIT and SIT was 2.9, 27.3, and 52.7 µg/mL, respectively. In general, a good fit to the probit statistical model was only achieved using the LPT. The results obtained in this study impair recommendations for using the LIT and SIT to diagnose amitraz resistance in R. (B.) microplus populations. Additional studies are required to improve the sensitivity of these tests in relation to the LPT.Keywords: Rhipicephalus (Boophilus) microplus, amitraz, bioassays, resistance diagnosis. ResumoAmostras de Rhipicephalus (Boophilus) microplus coletadas à campo no Rio Grande do Sul, Brasil, foram analisadas pelos seguintes métodos: teste do pacote de larvas (TPL), teste de imersão de larvas (TIL) e teste de imersão em seringas (TIS). Os seguintes parâmetros foram determinados para cada população e para a amostra referência suscetível Mozo: concentração letal para 50% (CL 50 ) e seu intervalo de confiança de 95% (IC95%), inclinação da reta de regressão e os fatores de resistência (FR). Pelo TPL, apenas uma população foi sensível ao amitraz, com FR de 1,9. Utilizando a mesma técnica, as outras amostras apresentaram FR entre 92,9 e 3445,8 sendo consideradas resistentes. As CL 50 da cepa Mozo calculadas por meio do TPL, TIL e TIS foram 2,9, 27,3 e 52,7 µg/mL, respectivamente. De forma geral, a adequação ao modelo estatístico de probitos só foi alcançada com o uso do TPL. Os resultados obtidos no presente estudo limitam a recomendação de uso do TIL e TIS para diagnóstico de resistência ao amitraz em populações de R. (B.) microplus. Estudos adicionais são necessários para aprimorar a sensibilidade destes testes em relação ao LPT.Palavras-chave: Rhipicephalus (Boophilus) microplus, amitraz, bioensaio, diagnóstico de resistência.

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Section: Introductionmentioning

confidence: 99%

“…Amitraz is the acaricide most used in the southern region of the state of Rio Grande do Sul, Brazil (VARGAS et al, 2003;FARIAS et al, 2008;SANTOS et al, 2009). It has some advantages over other acaricides, such as low toxicity to cattle and short withdrawal periods for milk (one day) and meat (14 days).…”

Section: Introductionmentioning

confidence: 99%

Comparison of three larval bioassays to evaluate susceptibility of Rhipicephalus (Boophilus) microplus to amitraz

Santos

Klafke²,

Pappen

et al. 2013

Rev. Bras. Parasitol. Vet.

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“…The drug of choice for the environmental treatment, where 95% of the tick population can be found, has long been based on pyrethroids because this class of acaricide has greater residual power (Labruna & Machado, 2006). However, recently, due to the increase in resistance to pyrethroids, these were replaced by formamidines (Amitraz), to which, in the same way, some tick populations are creating resistance (Farias et al, 2008;Santos et al, 2009). Thus, the search for new products, especially of natural sources, is an alternative that should be considered.…”

Section: Fonte: Autores (2021)mentioning

confidence: 99%

Acaricide activity of Piper macedoi Yunck essential oil against Rhipicephalus sanguineus

Bezerra

Ferreira

Santos

et al. 2022

RSD

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This study evaluated the acaricide efficacy of Piper macedoi essential oil on larvae of ticks of the species Rhipicephalus sanguineus. The essential oil was extracted by hydrodistillation in a Clevenger-type apparatus. The test consisted of six treatments: from the group I to IV, samples corresponded to different concentrations of essential oil (500 μg.mL-1; 250 μg.mL-1; 100 μg.mL-1 and 50 μg.mL-1) diluted in Tween 80 at 2%. Groups V and VI corresponded to the negative controls (with distilled water and Tween 80 to 2%) and the positive control (with acaricide Amitraz at 12.5%), respectively. The essential oil was rich in apiole (39.81%) and dillapiole (26.47%). The essential oil of P. macedoi presented an activity against the larvae of R. sanguineus, with a better efficiency observed for concentrating 500 μg.mL-1, mortality of 80.67%, indicating a dose-dependent response.

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“…microplus. This compound is the most commonly used acaricide in some regions of Brazil (Vargas et al, 2003;Farias et al, 2008;Santos et al, 2009). It has some advantages over other acaricides, such as low toxicity to cattle and short withdrawal periods for milk (one day) and meat (14 days).…”

Section: Introductionmentioning

confidence: 99%

Ten years later: Evaluation of the effectiveness of 12.5% amitraz against a field population of Rhipicephalus (Boophilus) microplus using field studies, artificial infestation (Stall tests) and adult immersion tests

Maciel

Lopes

Cruz

et al. 2015

Veterinary Parasitology

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Using field trials, artificial infestations (Stall tests) and in vitro adult immersion tests, the present study evaluated the acaricidal efficacy of 12.5% amitraz administered via whole body spraying against a Rhipicephalus (Boophilus) microplus population that did not have any contact with chemical products belonging to this acaricide family for 10 years (approximately 40 generations). Two natural infestation trials, two artificial infestation trials (Stall tests) and two adult immersion tests were performed in two different stages in 2005 and 2015. Between 2002 and 2015, the bovine herd of this property was formed by approximately 450 animals from the Simmental breed that were divided into nine paddocks formed by Cynodon dactylon (L.) Pers. For the natural infestation experiments in 2005 and 2015, we selected nearly 70 animals naturally infested with ticks from the same herd that belonged to the "São Paulo" farm located in São José do Rio Pardo, São Paulo, Brazil. Field studies were performed in the same paddock (9). To evaluate anti-R. (B.) microplus activity in the artificially infested cattle (Stall tests) and adult immersion tests, two experiments of each methodology were performed at CPPAR (the Center of Research in Animal Health located on the FCAV/UNESP campus in Jaboticabal, São Paulo, Brazil) in 2005 and 2015. R. (B.) microplus used in the artificial infestation, and adult immersion test experiments were obtained from paddocks 1-9 in 2005 and 2015 from the commercial farm where the field studies were performed. Based on the obtained results, it was possible to conclude that amitraz use in rotation with pyrethroids every 28 days for three consecutive years (2002-2004) previous to the beginning of the first trial (2005) was sufficient to generate a R. (B.) microplus strain resistant to amitraz. Moreover, using field trials, artificial infestations (Stall tests) and adult immersion tests, we verified that 40 generations of the tick species with no contact to the aforementioned compound (amitraz) were not sufficient to revert or modify the efficacy/resistance of amitraz for this analyzed R. (B.) microplus strain. The reversion of amitraz efficacy values in R. (B.) microplus may only occur when resistance of the field strain is incipient. Alternatively, the differences in the results may be due to differences in the Rhipicephalus spp. species between current study locations. Therefore, future studies must be performed to prove this hypothesis.

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Análise in vitro da efcácia do amitraz sobre populaÇões de Rhipicephalus (Boophilus) microplus (Canestrini, 1887) da região sul do Rio Grande do Sul

Cited by 8 publications

References 6 publications

Comparison of three larval bioassays to evaluate susceptibility of Rhipicephalus (Boophilus) microplus to amitraz

Comparison of three larval bioassays to evaluate susceptibility of Rhipicephalus (Boophilus) microplus to amitraz

Acaricide activity of Piper macedoi Yunck essential oil against Rhipicephalus sanguineus

Ten years later: Evaluation of the effectiveness of 12.5% amitraz against a field population of Rhipicephalus (Boophilus) microplus using field studies, artificial infestation (Stall tests) and adult immersion tests

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