Determination of Acaricide Resistance in <I>Rhipicephalus (Boophilus) microplus</I> (Acari: Ixodidae) Field Populations of Argentina, South Africa, and Australia With the Larval Tarsal Test

Abstract

Infestations with ticks have an important economic impact on the cattle industry worldwide and resistance to acaricides has become a widespread phenomenon. To optimize their treatment strategy, farmers need to know if and against which classes potential acaricide-resistance does occur. Bioassays are used to assess the resistance level and pattern of Rhipicephalus (Boophilus) microplus populations. The objective of the current study was to assess the susceptibility of Þeld populations originating from Argentina (8), South Africa (3), and Australia (2) using the Larval Tarsal Test. Nine acaricidal compounds from Þve major classes were tested: organosphosphates, synthetic pyrethroids (SP), macrocyclic lactones, phenylpyrazols, and amidines. The resistance ratios at concentrations inducing 50 and 90% mortality were used to detect established and emerging resistance. This study conÞrmed the newly reported presence of amitraz resistance in populations from Argentina. In addition, resistance to SP appeared to be widespread (88%) in the Argentinean farms, which had been selected based on the observation of lack of treatment efÞcacy by farmers. In South Africa one of the three populations was found to be resistant to SP and to a phenylpyrazol compound (pyriprol). Furthermore, resistance to organosphosphates and SP was observed in Australia. Finally, the Larval Tarsal Test proved to be a suitable test to evaluate the susceptibility of R. microplus Þeld populations to the most relevant acaricidal classes.RESUMEN Las infestaciones por garrapatas tienen un importante impacto económico en la industria del ganado de todo el mundo y la resistencia a los acaricidas se ha convertido en un fenómeno generalizado. Con el Þn de optimizar la estrategia de los tratamientos, los ganaderos necesitan saber en contra de cuáles clases de acaricidas ocurre esa potencial resistencia. Se utilizan bioensayos para evaluar el patrón y nivel de resistencia de Rhipicephalus (Boophilus) microplus. El objetivo del presente estudio fue evaluar la susceptibilidad de poblaciones de campo procedentes de Argentina (8), Sudáfrica (3) y Australia (2) usando la prueba del tarso de las larvas (LTT). Nueve compuestos acaricidas de cinco clases principales: organofosforados (OP), piretroides sintéticos (SP), lactonas macrocṍclicas (ML), fenilpirazoles (PYZ) y amidinas. Para detectar resistencia establecida y emergente, se calcularon niveles de resistencia basados en concentraciones que inducen mortalidad a 50% y 90%. Este estudio conÞrma la nueva denuncia de la presencia de resistencia al amitraz en las poblaciones de garrapatas de Argentina. Además, la resistencia a SP parece estar muy difundida (88%) en los establecimientos argentinos, seleccionados sobre la base de la observación de los ganaderos, de la falta de eÞcacia de los tratamientos. En Sudáfrica, en una de las tres poblaciones, se encontró que era resistente a SP y a un compuesto PYZ (pyriprol). Además, resistencia a OP y SP fue observada en Australia. Finalmente, la LTT ha demostrado ser un...

Amblyomma americanum tick saliva insulin‐like growth factor binding protein‐related protein 1 binds insulin but not insulin‐like growth factors

“…Current tick control methods are largely dependent on acaricide use. However sustainability of this strategy is threatened by numerous limitations, most notably: resistance development and environmental pollution (Wharton, 1967; Wang et al ., 1994; Lovis et al ., 2013; Coles & Dryden, 2014). Anti-tick vaccination is a feasible alternative (Willadsen, 2005).…”

Acaricide resistance of Rhipicephalus microplus ticks in Benin

“…The identification of ticks and resistance tests were performed in the Laboratory of Biotechnology Research Unit of the Animal Production and Health (the URBPSA) at the Polytechnic School of Abomey Calavi (PSAC) of University of Abomey in Benin. For the purposes of the acaricide resistance test, 50 engorged females ticks collect on at least ten animals (maximum eight of one animal) identified as R. microplus for each of the five farms were placed in empty vials perforated medium fine mesh and placed in an incubator at a temperature between 27 and 29°C with a relative humidity between 85 and 95% (Lovis et al, 2013).…”

“…After oviposition, the eggs were collected during 3 to 4 days postlaying, weighed and placed in tubes covered with fine mesh fabric at a rate of 0.5 g per tube. The larvae used in these resistance tests (Lovis et al, 2013).…”

“…The concentrations used in our tests ranged from 0.0156 to 4%, depending on each lethal concentration known of acaricide (Adakal et al, 2013a;Lovis et al, 2013).…”

“…In the West African sub-region, all toxicology studies have been made on other tick species then Rhipicephalus geigyi and revealed no ticks resistance (Adakal et al, 2013b;Jongejan and Uilenberg, 2004;Kaljouw, 2008). Until now, no study has been conducted in Benin in order to determine the effectiveness of different acaricides used to control ticks, although R. microplus ticks are known to have developed resistance to many acaricides (Chevillon et al, 2007;Kumar et al, 2012;Lovis et al, 2013).…”