title: Novel Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Varroa destructor Populations from the Southeastern USA.
abstract: The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V) of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here, we identify two novel mutations, L925M and L925I, in tau-fluvalinate resistant V. destructor collected at seven sites across Florida and Georgia in the Southeastern region of the USA. Using a multiplexed TaqMan® allelic discrimination assay, these mutations were found to be present in 98% of the mites surviving tau-fluvalinate treatment. The mutations were also found in 45% of the non-treated mites, suggesting a high potential for resistance evolution if selection pressure is applied. The results from a more extensive monitoring programme, using the Taqman® assay described here, would clearly help beekeepers with their decision making as to when to include or exclude pyrethroid control products and thereby facilitate more effective mite management programmes.
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.|ERI BIOTECMED, Department of Genetics, Universitat de València, Valencia, Spain.
authors.forename: Joel
authors.initials: J
authors.lastname: González-Cabrera
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.
authors.forename: Sonia
authors.initials: S
authors.lastname: Rodríguez-Vargas
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.
authors.forename: T G Emyr
authors.initials: TG
authors.lastname: Davies
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Field
authors.affiliation: Department of Entomology and Nematology, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Daniel
authors.initials: D
authors.lastname: Schmehl
authors.affiliation: Department of Entomology and Nematology, University of Florida, Gainesville, Florida, United States of America.
authors.forename: James D
authors.initials: JD
authors.lastname: Ellis
authors.affiliation: Bayer Animal Health GmbH, Leverkusen, Germany.
authors.forename: Klemens
authors.initials: K
authors.lastname: Krieger
authors.affiliation: Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Williamson
mesh_terms: D000818:Animals; D019476:Insect Proteins / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides / Q000633:toxicity; D009154:Mutation; D011722:Pyrethrins / Q000633:toxicity; D015144:Southeastern United States; D057077:Varroidae / Q000187:drug effects / Q000235:genetics*; D061566:Voltage-Gated Sodium Channels / Q000235:genetics*
chemical_list: D019476:Insect Proteins; D007306:Insecticides; D011722:Pyrethrins; D061566:Voltage-Gated Sodium Channels