In order to compensate the dramatic losses of honeybee colonies that we see globally for many years now, beekeepers try to restore their apiaries by importing colonies or queens in the hopes that those survive better than their previous bees. Such imports increase the level of introgression with local honeybee populations in which genetic variability is geographically highly structured.
In response to this a number of European countries started to preserve honeybee endemic diversity through conservation programs. They've realized that healthy natural populations can act as a reservoir against losses due to occasional diseases. Dedicated conservation programs will eventually provide various honeybee strains and traits that are suitable for sustainable beekeeping.
In a newly published study, researchers analysed the relationships between individuals of the honey bee subspecies Apis mellifera mellifera in a conservation centre, a drone congregation area, and the surrounding populations.
Honeybees have a very complex mating system in which drones and virgin queens meet mid-air to mate in areas that have been named drone congregation areas. Drones assembled in such a drone congregation area come from several surrounding colonies and thereby represent the diversity of the entire local population. These congregation areas are considered panmictic structures of honeybee reproduction and ensure a sufficient level of recombination.
The aim of this study was to analyse the effects of setting up a honeybee conservation centre regarding 1) the putative influence of the surrounding populations, 2) the drone congregation area variability over the years and its potential impact on the conserved honeybee populations and 3) the temporal composition of the drone congregation area located within the conservation centre, to estimate the risks of future introgressions on the conservation centre by external drones.
By using mtDNA COI-COII intergenic region and a restriction enzyme approach the French-American team was able to show that the colonies of the conservation centre and the drones of the congregation area show similar stable profiles when compared to the surrounding populations. This means that the centre studied represents an efficient conservation approach although it is located in an area with a high risk of geneflow from the surrounding populations.
In conclusion, this study introduced a new tool for setting up and monitoring honeybee conservation centres. This approach is based on the mtDNA marker to sort the colonies and to follow the evolution of the haplotype frequencies either in the conservation centre or in the DCA. This approach is particularly important to estimate the efficiency of the conservation process in the long term, so that quick measures can be taken when facing a risk of introgression.