Varroa destructor Parasitism and Genetic Variability at Honey Bee (Apis mellifera) Drone Congregation Areas and Their Associations With Environmental Variables in Argentina

SCANNAPIECO, ALEJANDRA CARLA; ESCALANTE, KAREN; AYUB, MARTA; LANDI, LUCAS; GALINDO-CARDONA, ALBERTO; GERIA, MARTÍN; MUNTAABSKI, IRINA; GIRAY, TUGRUL; RUSSO, ROMINA; LEPORI, NICOLÁS; LIENDO, MARÍA C.; MONMANY GARZIA, CAROLINA

Frontiers in Ecology and Evolution

Frontiers

Año: 2020 vol. 8

2296-701X

Varroa destructor is a serious ectoparasite of the western honey bee, Apis mellifera,which negatively impacts on colonies health and survival worldwide. Drone-mediatedmovement and the presence of the mite in Drone Congregation Areas (DCA) may playa relevant role in Varroa dispersal. The objectives of this study were to characterizemite infestation levels and genetic diversity in DCAs and surrounding apiaries and toexplore putative environmental variables associated to Varroa infestation in two ecoclimatic regions of Argentina (temperate, and subtropical). Phoretic mite proportionsin DCAs and apiaries were estimated during spring. Landscape, topographic, andclimate variables were described using satellite image classifications and data frompublic databases. The genetic composition of drones at the DCAs and workers from thesurrounding apiaries was assessed using mitochondrial markers. In total, eleven DCAswere identified in both regions during 2017 and 2018. The mean proportion of Varroawas ca. 3 in 1,000 (0.0028 ± 0.0046) at the apiaries, and ca. 2 in 100 (0.0168 ± 0.0227)at the DCAs. No statistical differences were observed between apiaries and DCAs orbetween ecoregions, but the proportion of infested males at the DCAs was positivelycorrelated to the distance to the apiary and a trend was observed toward higher miteloads in DCAs. Landscape and topography were not determinant for Varroa infestationat the DCAs but relative humidity and precipitation in the previous week of sampling,positively influenced infestation. More haplotypic diversity was detected in the DCAscompared to the surrounding apiaries, particularly in the subtropical region. While inthis region high prevalence of Africanized (A1, A4) mitochondrial lineages was detected,European lineages (C1, C2j) were mostly found in apiaries and DCA in the temperateregion. Our results provide valuable information on the dynamics of Varroa parasitism in apiaries and DCAs, and highlight the role of drones in mite dispersion and geneticvariability of new colonies. The study of DCAs emerges as a tool for investigating notonly honey bee reproduction and conservation, but also the impact of the environmenton bee epidemiology.