Rotation of treatments between spinosad and amitraz for the control of Rhipicephalus (Boophilus) microplus populations with amitraz resistance

Jonsson, N.N.; Miller, Robert J.; Kemp, D. H.; Knowles, A. G.; Ardila, Andres; Verrall, R. G.; Rothwell, J.

doi:10.1016/j.vetpar.2009.12.026

Cited by 36 publications

(23 citation statements)

References 19 publications

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“…Initially, in the absence of any molecular tools for population analysis, we intended to determine whether there was a loss of amitraz resistance when amitraz was withdrawn from use on a population of ticks, and whether a rotation strategy using amitraz and spinosad could be effective when resistance-conferring genes were already present in a population. These findings have been reported elsewhere (14). Subsequently, as we have developed molecular tools for analyzing the R. microplus populations (9,(15)(16)(17), we examined population dynamics on a molecular genetic basis.…”

supporting

confidence: 71%

“…A similar effect was seen in the Bayesian clustering of microsatellite markers, presumed to be spread across the genome. In later generations, particularly by Winter 2005, a fitness cost to amitraz resistance became evident, as documented in more detail elsewhere (14). This result was shown by a substantial loss in phenotypic amitraz resistance in the spinosadtreated groups and in the rotation groups.…”

Section: Discussionmentioning

confidence: 61%

“…Ticks were sourced from a 3-y field study investigating the management strategies for controlling amitraz resistance using amitraz and spinosad, commencing in 2003 at the University of Queensland Pinjarra Hills Campus (14). Detailed information on field study and the use of acaricides is provided in the Supporting Information.…”

Section: Methodsmentioning

confidence: 99%

“…Engorged females were collected and as many larvae as required for the bioassay were assayed using the LPT for acaricide resistance (24). The LPT was applied using discriminating concentrations of analytical grade cypermethrin (0.3%, 24 h incubation) and amitraz (0.5%, 48 h incubation) (14). Larvae that were not required for the bioassay were frozen at −20°C and DNA extracted.…”

Section: Methodsmentioning

confidence: 99%

“…Based on observed fluctuations in the numbers of ticks counted each week on experimental animals (14), each collection of ticks for LPT was assigned to a putative generation from 0 (ticks applied in the artificial infestation) to 7 (collection made in Winter 2005). The effects of treatment*generation (0-7), replicate (1, 2) and genotype (RmβAOR SNP I61F) on the percentage resistance calculated by LPT were tested using the mixed procedure of SAS (v9.2, SAS Institute), using restricted maximum-likelihood as the parameter estimation method.…”

Section: Methodsmentioning

confidence: 99%

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Mutation in the RmβAOR gene is associated with amitraz resistance in the cattle tick Rhipicephalus microplus

Corley

Jonsson

Piper

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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We aimed to describe the evolution of resistance to amitraz in Rhipicephalus microplus in the field and to test the association between amitraz resistance and the frequency of a mutation in the β-adrenergic octopamine receptor gene (RmβAOR). We established six populations of Rhipicephalus microplus ticks in similar paddocks by the admixture of ticks from strains known to be susceptible and resistant to amitraz and synthetic pyrethroids. Each population was managed using one of three acaricide treatment regimes: always amitraz, always spinosad, or rotation between amitraz and spinosad. We used microsatellites to elucidate population structure over time, an SNP in the para-sodium channel gene previously demonstrated to confer resistance to synthetic pyrethroids to quantify changes in resistance to synthetic pyrethroids over time, and a nonsynonymous SNP in the RmβAOR, a gene that we proposed to confer resistance to amitraz, to determine whether selection with amitraz increased the frequency of this mutation. The study showed panmixia of the two strains and that selection of ticks with amitraz increased the frequency of the RmβAOR mutation while increasing the prevalence of amitraz-resistance. We conclude that polymorphisms in the RmβAOR gene are likely to confer resistance to amitraz.

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supporting

confidence: 71%

Section: Discussionmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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