title: An integrative approach to understanding pyrethroid resistance in Rhipicephalus microplus and R. decoloratus ticks.
abstract: Rhipicephalus microplus and Rhipicephalus decoloratus species occur in regions with savannah and temperate climates, typically in grassland and wooded areas used as cattle pasture. Both species are associated with the transmission of Anaplasma and Babesia spp., impacting livestock health and quality of livestock-associated products. In Africa, tick control is predominantly mediated with the use of acaricides, such as synthetic pyrethroids. After several years on the market, reports of resistance to synthetic pyrethroids escalated but limited field data and validation studies have been conducted to determine the extent of acaricide resistance in Africa. Without this data, knowledge-based tick control will remain problematic and selection pressure will remain high increasing the rate of resistance acquisition. To date, several pyrethroid resistance associated single nucleotide polymorphisms (SNPs) have been reported for arthropods within the voltage-gated sodium channel. Three SNPs have been identified within this channel in pyrethroid resistant R. microplus ticks, but none has been reported for R. decoloratus. This study is the first to report the presence of a shared SNP within the voltage-gated sodium channel in both R. microplus and R. decoloratus, which is directly linked to pyrethroid resistance in R. microplus. As the mode of action by which these SNPs mediate pyrethroid resistance remains unknown, this study aims to set hypotheses by means of predictive structural modelling. This not only paves the way forward to elucidating the underlying biological mechanisms involved in pyrethroid resistance, but also improvement of existing acaricides and ultimately sustainable tick control management.
authors: Department of Biochemistry, University of Pretoria, Pretoria, South Africa.
authors: Roelof Dj van
authors: RDj
authors: Wyk
authors: Department of Genetics, University of Pretoria, Pretoria, South Africa.
authors: Samantha
authors: S
authors: Baron
authors: Department of Genetics, University of Pretoria, Pretoria, South Africa. Electronic address: Christine.maritz@up.ac.za.
authors: Christine
authors: C
authors: Maritz-Olivier
mesh_terms: D056810:Acaricides / Q000494:pharmacology*; D000818:Animals; D004351:Drug Resistance; D020641:Polymorphism, Single Nucleotide; D011722:Pyrethrins / Q000494:pharmacology*; D048494:Rhipicephalus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D061566:Voltage-Gated Sodium Channels / Q000235:genetics
chemical_list: D056810:Acaricides; D011722:Pyrethrins; D061566:Voltage-Gated Sodium Channels
keywords: Rhipicephalus decoloratus; Rhipicephalus microplus; SNPs; acaricide resistance; drug docking; protein modelling; pyrethroids