Mutation in the Rm-beta-AOR gene is associated with amitraz resistance in the cattle tick Rhipicephalus microplus

Corley, Sean W., Jonsson, Nicholas N., Piper, Emily K., Cutullé, Christian, Stear, Michael J. and Seddon, Jennifer M. (2013) Mutation in the Rm-beta-AOR gene is associated with amitraz resistance in the cattle tick Rhipicephalus microplus. Proceedings of the National Academy of Sciences, 110 42: 16772-16777. doi:10.1073/pnas.1309072110

Author Corley, Sean W.
Jonsson, Nicholas N.
Piper, Emily K.
Cutullé, Christian
Stear, Michael J.
Seddon, Jennifer M.
Title Mutation in the Rm-beta-AOR gene is associated with amitraz resistance in the cattle tick Rhipicephalus microplus
Formatted title
Mutation in the RmβAOR gene is associated with amitraz resistance in the cattle tick Rhipicephalus microplus
Journal name Proceedings of the National Academy of Sciences   Check publisher's open access policy
ISSN 0027-8424
Publication date 2013-10-15
Year available 2013
Sub-type Article (original research)
DOI 10.1073/pnas.1309072110
Open Access Status Not yet assessed
Volume 110
Issue 42
Start page 16772
End page 16777
Total pages 6
Editor May R. Berenbaum
Place of publication Washington, DC, United States
Publisher National Academy of Sciences
Language eng
Abstract Amitraz is an important product for the control of cattle ticks around the world. In comparison with other products for the control of ticks, it is quite affordable and it has a rapid knock-down effect. It binds with and activates adrenergic neuro-receptors of animals and it inhibits the action of monoamine oxidases (MAO). Resistance to amitraz has been documented in Rhipicephalus microplus, R. decoloratus and R. appendiculatus. Four mechanisms of resistance have been proposed, each of which is supported by evidence but none of which has been definitively confirmed as the cause of resistance in the field. The proposed mechanisms include genetic target site insensitivity in two G protein-coupled receptors, the beta-adrenergic octopamine receptor (BAOR) and the octopamine/tyramine receptor (OCT/Tyr), increased expression or activity of monoamine oxidases and increased expression or activity of the ATP binding cassette transporter.
Formatted abstract
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.

Significance Amitraz is a widely used acaricide for the control of the cattle tick Rhipicephalus microplus, an important parasite of cattle in the tropics and subtropics. Here we describe in detail the evolution of amitraz resistance in replicated populations of ticks in the field, using divergent selection pressures with amitraz. We also demonstrate a close association between resistance to amitraz and a specific allele of the β-adrenergic octopamine receptor gene, which we propose confers resistance to amitraz.
Keyword Multidisciplinary Sciences
Science & Technology - Other Topics
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Veterinary Science Publications
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Citation counts: TR Web of Science Citation Count  Cited 11 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 14 times in Scopus Article | Citations
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Created: Thu, 31 Oct 2013, 23:34:09 EST by Dr Emily Piper on behalf of School of Veterinary Science