title: Seasonal cycle of inbreeding and recombination of the parasitic mite Varroa destructor in honeybee colonies and its implications for the selection of acaricide resistance.
abstract: Varroa destructor is the most devastating parasite of the Western honeybee, Apis mellifera. In the light of the arm race opposing the host and its parasite, the population dynamics and genetic diversity of these organisms are key parameters. However, the life cycle of V. destructor is characterized by extreme inbreeding due to full sibling mating in the host brood cells. We here present an equation reflecting the evolution of inbreeding in such a clonal system, and compare our predictions with empirical data based on the analysis of seven microsatellite markers. This comparison revealed that the mites perform essentially incestuous mating in the beginning of the brood season. However, this pattern changes with the development of mite infestation. Despite the fact that the overall level of genetic diversity of the mites remained low through the season, multiple inbred lineages were identified in the mites we sampled in June. As a response to the decrease of brood availability and the increase of the parasite population in parallel in the colonies, these lineages recombined towards the end of the season as mites co-infest brood cells. Our results suggest that the ratio of the number of mite per brood cell in the colony determines the genetic structure of the populations of V. destructor. This intracolonial population dynamics has great relevance for the selection of acaricide resistance in V. destructor. If chemical treatments occur before the recombination phase, inbreeding will greatly enhance the fixation of resistance alleles at the colony level.
authors.affiliation: Institut für Biologie, Martin-Luther-University Halle-Wittenberg, Halle a.d. Saale, Germany; UR 406 Abeilles et Environnement, INRA, Centre de Recherche Provence-Alpes-Côte d'Azur, Avignon, France. Electronic address: Alexis.Beaurepaire@inra.fr.
authors.forename: Alexis L
authors.initials: AL
authors.lastname: Beaurepaire
authors.affiliation: Bayer Animal Health GmbH, Leverkusen, Germany.
authors.forename: Klemens J
authors.initials: KJ
authors.lastname: Krieger
authors.affiliation: Institut für Biologie, Martin-Luther-University Halle-Wittenberg, Halle a.d. Saale, Germany; Dept Zoology, Entomology University of Pretoria, Pretoria, South Africa.
authors.forename: Robin F A
authors.initials: RFA
authors.lastname: Moritz
mesh_terms: D056810:Acaricides / Q000494:pharmacology; D000818:Animals; D001516:Bees / Q000469:parasitology*; D004351:Drug Resistance / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D006790:Host-Parasite Interactions; D007178:Inbreeding; D008297:Male; D018895:Microsatellite Repeats; D008924:Mite Infestations / Q000469:parasitology*; D011157:Population Dynamics; D011995:Recombination, Genetic; D012621:Seasons; D057077:Varroidae / Q000187:drug effects / Q000235:genetics*
chemical_list: D056810:Acaricides
keywords: Apis mellifera; Host-parasite coevolution; Microsatellites; Population dynamics; Population genetics; Varroa destructor