title: Global distribution and origin of target site insecticide resistance mutations in Tetranychus urticae.
abstract: The control of Tetranychus urticae, a worldwide agricultural pest, is largely dependent on pesticides. However, their efficacy is often compromised by the development of resistance. Recent molecular studies identified a number of target site resistance mutations, such as G119S, A201S, T280A, G328A, F331W in the acetylcholinesterase gene, L1024V, A1215D, F1538I in the voltage-gated sodium channel gene, G314D and G326E in glutamate-gated chloride channel genes, G126S, I136T, S141F, D161G, P262T in the cytochrome b and the I1017F in the chitin synthase 1 gene. We examined their distribution, by sequencing the relevant gene fragments in a large number of T. urticae collections from a wide geographic range. Our study revealed that most of the resistance mutations are spread worldwide, with remarkably variable frequencies. Furthermore, we analyzed the variability of the ace locus, which has been subjected to longer periods of selection pressure historically, to investigate the evolutionary origin of ace resistant alleles and determine whether they resulted from single or multiple mutation events. By sequencing a 1540 bp ace fragment, encompassing the resistance mutations and downstream introns in 139 T. urticae individuals from 27 countries, we identified 6 susceptible and 31 resistant alleles which have arisen from at least three independent mutation events. The frequency and distribution of these ace haplotypes varied geographically, suggesting an interplay between different mutational events, gene flow and local selection.
authors.affiliation: Faculty of Biotechnology and Applied Biology, Department of Biology, University of Crete, P.O. Box 2208, 71409 Heraklion, Greece; Hellenic Agricultural Organisation "Demeter", NAGREF, Plant Protection Institute of Heraklion, P.O. Box 2228, 71003 Heraklion, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Ilias
authors.affiliation: Faculty of Biotechnology and Applied Biology, Department of Biology, University of Crete, P.O. Box 2208, 71409 Heraklion, Greece.
authors.forename: J
authors.initials: J
authors.lastname: Vontas
authors.affiliation: Hellenic Agricultural Organisation "Demeter", NAGREF, Plant Protection Institute of Heraklion, P.O. Box 2228, 71003 Heraklion, Greece. Electronic address: tsagkarakou@nagref.gr.
authors.forename: A
authors.initials: A
authors.lastname: Tsagkarakou
mesh_terms: D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D051456:Gene Flow; D005843:Geography; D007305:Insecticide Resistance / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D040102:Tetranychidae / Q000235:genetics*
keywords: Acetylcholinesterase; Resistance evolution; Spider mites; Target site point mutations