Characterization of the pyrethroid resistance profile of Rhipicephalus (Boophilus)microplus populations from the states of Rio Grande do Sul and Mato Grosso do Sul, Brazil

Abstract

Cattle ticks Rhipicephalus (Boophilus) microplus are mainly controlled in Brazil by means of acaricide products, without any official policies in this regard. Acaricides continue to be sold indiscriminately, and this has contributed towards making the problem of resistance widespread, thus making diagnosis and monitoring of tick resistance essential. Here, bioassays (larval packet test) were performed on tick populations from the states of Rio Grande do Sul and Mato Grosso do Sul regarding their susceptibility to cypermethrin, deltamethrin and flumethrin. All the tick samples tested showed resistance to cypermethrin (10) (resistance factor (RF) ranging from 5.6 to 80.3) and deltamethrin (10) (RF ranging from 2.4 to 83.1). Six out of eight populations were resistant to flumethrin (RF ranging from 3.8 to 8.2). PCR molecular analyses did not show any T2134A mutations in the voltage-gated sodium channel gene, in any of the sampled populations. The results from this study highlight the critical status of resistance of the cattle tick to synthetic pyrethroids in the regions studied. Further studies are needed to identify the mechanisms responsible for the resistant phenotypes observed in the bioassays. This was the first detection of flumethrin resistance in Brazil.Keywords: Cattle tick, acaricide resistance, synthetic pyrethroids, PCR. ResumoO controle do carrapato Rhipicephalus (Boophilus) microplus no Brasil é feito principalmente com produtos acaricidas, sem uma política de controle oficial. A venda destes produtos continua ocorrendo de maneira indiscriminada, o que tem contribuído para generalizar o problema da resistência em todo o país, tornando essencial seu diagnóstico e monitoramento. Bioensaios (teste do pacote de larvas) foram conduzidos com populações de carrapatos do Rio Grande do Sul e Mato Grosso do Sul, com relação à sua suscetibilidade a três princípios ativos piretróides. Todas as amostras analisadas mostraram resistência à cipermetrina (10), com fatores de resistência (FR) de 5,6 a 80,3, e à deltametrina, com FR variando de 2,4 a 83,1. Seis das oito amostras foram resistentes à flumetrina (FR de 3,8 a 8,2). Análises moleculares utilizando PCR demonstraram que em todas as populações amostradas não foram encontrados alelos com a mutação T2134A no gene do canal de sódio controlado por voltagem. Os resultados deste estudo evidenciam a situação crítica da resistência do carrapato bovino ao grupo dos piretróides sintéticos nas regiões estudadas. Novos estudos são necessários para identificar os mecanismos responsáveis pelos fenótipos resistentes observados nos bioensaios. Este é o primeiro relato da resistência a flumetrina no Brasil.

In VitroDetection of Acaricidal Resistance Status ofRhipicephalus (Boophilus) microplusagainst Commercial Preparation of Deltamethrin, Flumethrin, and Fipronil from North Gujarat, India

“…Further, farmers were reluctant to adopt this chemical owing to longer milk withholding period. Mendes et al [ 21 ] reported LC 50 of susceptible (Mozo) strain as 50 ppm by LPT. Resistance factor of ticks against flumethrin could not be determined owing to lack of data on reference tick line; however, resistance to synthetic pyrethroids is usually described in terms of family resistance where ticks simultaneously develop resistance to more than one compound of the group [ 19 , 22 ].…”

Efficacy profile of Cypermethrin and Chlorpyrifos based acaricides on Rhipicephalus microplus control on cattle in the rearing phase, naturally infested and exposed to tick fever agents in central Brazil

“…The acaricides efficacy evaluation studies in Brazil are not systematic, and the presence of resistance to different chemical bases is a reality reported in several regions of the country (Andreotti et al, 2011, Higa et al, 2015, Klafke et al, 2017. In the region in which this study was conducted, there are populations of this tick that are highly resistant to cypermethrin-based acaricides, a fact that was previously identified by Andreotti et al (2011) and Mendes et al (2013).…”

Development of acaricide resistance in tick populations of cattle: A systematic review and meta-analysis

“…Organophosphates were heavily used in the national tick eradication program between 1974 and 1984, whereas pyrethroids and amitraz were introduced to Mexico in 1986 (Rodriguez-Vivas et al, 2014). In Brazil, reports of tick populations exhibiting resistance to acaricides are mainly from the southern Brazilian states of Rio Grande do Sol, São Paulo, and Mato Grosso do Sul Brazil (Klafke et al, 2006(Klafke et al, , 2017Castro-Janer et al, 2010;Andreotti et al, 2011;Mendes et al, 2011Mendes et al, , 2013. According to de Oliveira Souza Higa et al (2015), acaricide resistance development in Brazilian populations of R.…”