The genetic origin of honey bee colonies used in the COLOSS Genotype-Environment Interactions Experiment: a comparison of methods

Abstract

SummaryThe COLOSS GEI (Genotype-Environment Interactions) Experiment was setup to further our understanding of recent honey bee colony losses. The main objective of the GEI experiment was to understand the effects of environmental factors on the vitality of European honey bee genotypes. This paper aims to describe the genetic background and population allocation of the bees used in this experiment. Two wing morphometric and two genetic methods were employed to discriminate bee populations. Classical morphometry of 11 angles on the wings were carried out on 350 bees. Geometric morphometry on 19 wing landmarks was carried out on 381 individuals. DNA microsatellite analysis was carried out on 315 individuals using 24 loci. Allozyme analysis was performed on 90 individuals using six enzyme systems. DNA microsatellite markers produced the best discrimination between the subspecies (Apis mellifera carnica, A. m. ligustica, A. m. macedonica, A. m. mellifera and A. m. siciliana) used in the experiment. Morphometric methods generally showed an intermediate level of discrimination, usually best separating A. m. siciliana and A. m. ligustica from the remaining populations. Allozyme markers lack power to discriminate at the level of individual bees, and given our sample size, also fail to differentiate subspecies. Based on DNA microsatellites, about 69% of the individuals were assigned to the same subspecies as originally declared, and 17% were found to belong to a different subspecies. Fourteen percent of the samples were found to be of mixed origin and could not be assigned to any subspecies with certainty. We further discuss the caveats of the methods and details of the sampled bees, their origins and breeding programmes in their respective locations.