title: A selective sweep in a Varroa destructor resistant honeybee (Apis mellifera) population.
abstract: The mite Varroa destructor is one of the most dangerous parasites of the Western honeybee (Apis mellifera) causing enormous colony losses worldwide. Various chemical treatments for the control of the Varroa mite are currently in use, which, however, lead to residues in bee products and often to resistance in mites. This facilitated the exploration of alternative treatment methods and breeding for mite resistant honeybees has been in focus for breeders in many parts of the world with variable results. Another approach has been applied to a honeybee population on Gotland (Sweden) that was exposed to natural selection and survived Varroa-infestation for more than 10years without treatment. Eventually this population became resistant to the parasite by suppressing the reproduction of the mite. A previous QTL mapping study had identified a region on chromosome 7 with major loci contributing to the mite resistance. Here, a microsatellite scan of the significant candidate QTL regions was used to investigate potential footprints of selection in the original population by comparing the study population on Gotland before (2000) and after selection (2007). Genetic drift had caused an extreme loss of genetic diversity in the 2007 population for all genetic markers tested. In addition to this overall reduction of heterozygosity, two loci on chromosome 7 showed an even stronger and significant reduction in diversity than expected from genetic drift alone. Within the selective sweep eleven genes are annotated, one of them being a putative candidate to interfere with reduced mite reproduction. A glucose-methanol-choline oxidoreductase (GMCOX18) might be involved in changing volatiles emitted by bee larvae that might be essential to trigger oogenesis in Varroa.
authors: Institut für Biologie, Tierphysiologie, Martin-Luther-Universität Halle-Wittenberg, Domplatz 4, 06099 Halle (Saale), Germany; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany. Electronic address: lattorff@zoologie.uni-halle.de.
authors: H Michael G
authors: HM
authors: Lattorff
authors: Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg, Hoher Weg 4, 06099 Halle (Saale), Germany.
authors: Josephine
authors: J
authors: Buchholz
authors: Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7044, Uppsala 750-05, Sweden.
authors: Ingemar
authors: I
authors: Fries
authors: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany; Institut für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg, Hoher Weg 4, 06099 Halle (Saale), Germany; Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.
authors: Robin F A
authors: RF
authors: Moritz
mesh_terms: D000818:Animals; D001516:Bees / Q000235:genetics* / Q000469:parasitology*; D060467:Disease Resistance / Q000235:genetics*; D017344:Genes, Insect; D014644:Genetic Variation; D005838:Genotype; D018895:Microsatellite Repeats; D040641:Quantitative Trait Loci; D012641:Selection, Genetic; D057077:Varroidae
keywords: GMCOX18; Gene mapping; Genetic drift; Heterozygosity; QTL; Suppression of mite reproduction