title: Accumulation of acaricide resistance mechanisms in Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) populations from New Caledonia Island.
abstract: Rhipicephalus (Boophilus) microplus has been pesticide-controlled for several decades in the pacific island of New Caledonia. Since 1996, pesticide-control has been based on either deltamethrin (Butox) or amitraz (Taktic) in herds harbouring deltamethrin-resistant ticks. In this island, the first R. microplus deltamethrin- and amitraz-resistances were detected in 1992 and 2003, respectively. Using LPT bioassays, we have undertaken to update data regarding the geographical distribution and the physiological diversity likely to be involved in these resistances. We confirmed that after 17 years of intensive use of deltamethrin, several resistances of moderate levels (<30-fold) have evolved and/or diffused in any part of the island. We also evidenced that amitraz-resistant phenotypes have recently evolved in diverse western tick populations, although none has reached fixation in any tick population yet. According to synergists bioassays, the physiological changes involved in amitraz-resistance in New Caledonia would involve target modification and detoxifying P450 cytochrom oxydase(s). It may also involve detoxifying esterase(s) although this later point will need confirmation on samples bearing higher frequency of resistant phenotypes. Results are discussed with regard to the local evolutionary dynamics of resistance.
authors.affiliation: Génétique et Evolution des Maladies Infectieuses, UMR CNRS-IRD 2724, Centre IRD, 911 Avenue Agropolis, BP 64501, 34 394 Montpellier Cedex 5, France. Christine.Chevillon@mpl.ird.fr
authors.forename: Christine
authors.initials: C
authors.lastname: Chevillon
authors.forename: Sophie
authors.initials: S
authors.lastname: Ducornez
authors.forename: Thierry
authors.initials: T
authors.lastname: de Meeûs
authors.forename: Brou Basile
authors.initials: BB
authors.lastname: Koffi
authors.forename: Huguette
authors.initials: H
authors.lastname: Gaïa
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Delathière
authors.forename: Nicolas
authors.initials: N
authors.lastname: Barré
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology; D007305:Insecticide Resistance; D007306:Insecticides / Q000494:pharmacology*; D009510:New Caledonia / Q000453:epidemiology; D009570:Nitriles / Q000494:pharmacology*; D011722:Pyrethrins / Q000494:pharmacology*; D048494:Rhipicephalus / Q000187:drug effects*; D013984:Tick Infestations / Q000469:parasitology; D014052:Toluidines / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D014052:Toluidines; C017180:decamethrin; C014983:amitraz