Diagnosis of amitraz resistance in Brazilian populations of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) with larval immersion test

Abstract

Among the ectoparasites of cattle, Rhipicephalus (Boophilus) microplus (Canestrini) (Acari: Ixodidae) remains a major cause of economic losses to livestock. The chemical control with acaricides is still the most efficient method available to control ticks. The aims of this study were to diagnose resistance to amitraz in 16 tick populations from the States of São Paulo (14) and Paraná (2), using the larval immersion technique (LIT), and evaluate the effect of synergists [piperonyl butoxide (PBO), diethyl maleate (DEM), triphenyl phosphate (TPP)] on amitraz resistant and susceptible strains of cattle tick. Most of the evaluated populations (68.7 %) showed to be resistant to amitraz, with resistance ratios ranging from 2.14 to 132. The results suggest that the test procedure by LIT is sensitive and adequate for detection and monitoring of amitraz resistance in cattle tick. No synergistic effect was observed for the synergists PBO, DEM and TPP, on the amitraz resistant (Poa) strain of cattle tick, indicating that increased detoxification metabolism was not involved in this resistance.

Evaluation of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) resistance to different acaricide formulations using samples from Brazilian properties

“…microplus specimens from the states of São Paulo, Ceará, Minas Gerais and on many properties in Mato Grosso do Sul (Tables 2 and 3), with these products exhibiting efficacy ranging from zero to 100% for the three analyzed active ingredients (alpha-cypermethrin, cypermethrin and deltamethrin). These results confirmed the results obtained by Koller et al (2009), Gomes et al (2011) and Mendes et al (2013) in Mato Grosso do Sul and those obtained by Mendes et al (2001Mendes et al ( , 2011 and Pereira (2006) in the state of São Paulo. There are no reports of such resistance in Ceará (HIGA et al, 2015), but it has been reported in other states in the northeastern region of Brazil, including Bahia (CAMPOS & OLIVEIRA, 2005;RAYNAL et al, 2013) and Pernambuco (SILVA et al, 2005).…”

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

“…Although this assay has not yet been recognized by FAO as a trustworthy method for detecting acaricide resistance in tick populations, it has been used to assess the toxicity of chemicals that act systemically, such as fipronil (CASTRO-JANER et al, 2010) and ivermectin (KLAFKE et al, 2006(KLAFKE et al, , 2012. Recently, it was described as a reliable method for detecting resistance to amitraz (MENDES et al, 2013).…”

“…microplus can be diagnosed using the larval stage in in vitro bioassays: a) larval packet test (LPT), originally described by Stone and Haydock (1962), standardized by FAO (1971) and then modified by Miller et al (2002), with the aim of specifically diagnosing amitraz resistance; b) larval immersion test (LIT), originally described by Shaw (1966), then adapted for microcentrifuge tubes by Sabatini et al (2001) and used successfully for diagnosing resistance to ivermectin (KLAFKE et al 2006(KLAFKE et al , 2012 and fipronil (CASTRO-JANER et al, 2010); and c) syringe immersion test (SIT), described by Souza et al (2008) although not yet standardized for routine use as an acaricide resistance diagnostic tool. Recently, Mendes et al (2013) described the use of LIT for diagnosing amitraz resistance in R. (B.)…”

Evaluation of immune protection induced by DNA vaccines from Haemaphysalis longicornis paramyosin in rabbits

“…However, utilization of acaricides causes drug resistance in ticks, environmental contamination, and meat products with pesticide residues [4–6]. Vaccine has been considered as an efficient approach to control ticks [7, 8].…”