Below the various strategies which DarkBee.org follows to safeguard the survival of our native Dark bee will be discussed. An approach that strives for sustainable beekeeping, learning from how our Dark bees survive in the wild.
Author: Dylan Elen (November 2019)
The breeding strategy of DarkBee.org serves 2 aims: letting the Dark bees from Chimay (Belgium) and Texel (Netherlands) further adapt to the different environmental conditions within the Benelux and improving their performance considering traits such as gentleness, calmness, resistance to diseases and Varroa, etc. Therefore, it is important to organize this selective breeding at a local scale, because the local environment has an important impact on the expression of these traits.
Once started, selective breeding is a vicious cycle. To begin with, a selection is made from the group of breeding colonies, also called P-colonies – in this case pure Dark bee colonies – that stands out because of very good performances for traits such as gentleness, resistance to disease, being economical with food stores, … Within this selection of breeding colonies, some colonies will be chosen to become a mother line whilst others will be chosen as a father line.
Once the choice of mother and father lines has been made, the rearing of daughter queens of these breeding colonies can be started. In case of father lines, it is not necessary for these daughter queens to be mated purely – F1 queens are good enough – as they will only serve to produce drones for the controlled mating of daughter queens of the mother line breeding colonies at the mating position (or possibly via Artificial Insemination or Moonlight Mating). Ideally, the daughter queens of the father line breeding colonies are raised 1 year in advance. After the daughter queens of the mother line breeding colonies have been mated by drones of daughter queens of the father line breeding colonies, they can be introduced into artificial swarms at the different breeding apiaries. These colonies are known as test colonies.
When all the original worker bees from the artificial swarms have died off and been replaced by worker bees from the introduced queens, the process of performance testing starts. The test period continues until September of the following year. Hereby data is collected about gentleness, calmness, hygienic behavior, Varroa infestation, … of the test colonies at the breeding apiaries. All this data will finally be processed into breeding values, based on which can be decided which test colonies can serve as breeding colonies from the following year onwards. At this stadium the breeding cycle has been completed and can start over again. Beebreed.eu is used for the calculation of those breeding values.
The selective breeding protocol of DarkBee.org prescribes to have at least 3 different daughter queens of at least 3 different mother line breeding colonies present at each breeding apiary (so at least 9 test colonies per breeding apiary). Furthermore, daughters of each of those mother line breeding colonies must be present at at least 3 different breeding apiaries. This approach makes it possible to accurately determine the impact of the local environment on the exhibition of the tested traits when calculating breeding values. After all, the behaviour of honey bees is not purely determined by their genetics, but by its interaction with the local environment in which they are situated. This way, local adaptation can be taken into account. (Büchler et al. , 2014)
To make it easier for beekeepers to help maintain our Dark bee, it is important to increase the availability of genetic material. Therefore, DarkBee.org works on the development of a grafting network. This entails that, throughout the Benelux, there are locations where members of DarkBee.org can freely obtain larvae from breeding colonies during the grafting days. Beekeepers can introduce those young larvae into a nursing colony of their own and let their bees take care off rearing them into Dark queens. They can then have these queens mated either at their home apiary or for free at a mating station of DarkBee.org.
The period of reproduction of honey bees in our region is mainly May – July. Queens and drones mate in open air, at an altitude between 10 and 40 meters, between 2 pm and 4.30 pm above so-called drone congregation areas. These are locations which have a distinct landscape element that attracts queens and drones from far away. The distance traveled by queens to such a drone congregation area is up to 5 km, for drones it is even up to 7 km. (Koeniger et al ., 2014) These gigantic distances make conservation projects for native honey bees very difficult, especially in regions with a high density of beekeepers. After all, the drones (and queens) of beekeepers who keep non-native subspecies (e.g. Carniolan bees) or artificial breeds (e.g. Buckfast bees) gather at the same drone congregation areas as where the Dark queens (and drones) also gather. This way there is a continuous risk that a Dark queen mates with one or more non-Dark drones, which would result in her offspring being genetically polluted. This is the process behind the extinction of our Dark bee.
To avoid this hybridization risk, there is a need for conservation areas. Those are areas – preferably with a radius of at least 7 km – within which exclusively native Dark bees are kept. In the center of that conservation area, a mating station can be set up to where beekeepers from inside and outside the conservation area can bring their Dark queens in small mating nucs to be exclusively mated by Dark drones. The center of that conservation area should be far enough away from the periphery so that the chance of a Dark queen mating with a non-Dark drone is virtually non-existent.
In the year 2020, DarkBee.org has 2 mating stations in the Benelux. The first one is located in the Belgian Bosland woodland and was realized in collaboration with the Flemish Agency for Nature & Forest and a number of local nature conservation societies (Natuurpunt). The area in which this mating station is located, is not a conservation area so far, but a relatively large forest area with hardly any beekeepers (who keep non-native subspecies or artificial breeds) around. This location was tested on a small-scale for the first time in 2016 and turned out to be a bull’s-eye: not less than 50% of Dark queens were mated purely, based on wing morphometric research. This test was repeated successfully in the following years and in 2018 young worker bees originating from some of the queens mated overthere were collected for DNA analysis proving the potential of this mating station. Further research, including on the Flevopolder mating station (Netherlands), is currently ongoing.
In our region Dark bees, or genetically polluted descendants of them, were also found in the wild until the 20th century. These honey bee colonies lived in tree cavities, such as old nests of the Black Woodpecker (and in rocky areas possibly in crevasses). Back then, the honey bee population could be divided into “honey bee colonies of beekeepers” and “wild honey bee colonies”. But because of both of them sharing the same reproduction strategy, there was always interaction between both groups at the genetic level.
Nowadays, there are no more populations of wild honey bee populations around in the Benelux, though an accidentally escaped swarm can be found sometimes. These populations were first decimated by the excessive logging in the Middle Ages and the subsequent forest management. As a result, almost all primeval forests disappeared and potential nesting sites were massively destroyed. The deathblow, however, followed in the 1980s by the Varroa mite (Varroa destructor). This ectoparasite of subspecies of the Eastern honeybee (Apis cerana) arrived in Europe through global transport, and since then kills, indirectly via virus spread, all subspecies of the Western honeybee (Apis mellifera). Beekeepers used acaricides to fight the Varroa mite and save their honey bee colonies. The (last) wild honey bee colonies, however, did not receive any help and perished, especially due to the Varroa mite, but also due to the general decline of nature (forage resources) of course.
However, around the world, there are still populations of Western honey bees present that live in the wild and survive the Varroa mite. To this end, under the influence of natural selection, these honey bees have developed behavioural traits to control the amount of Varroa mites in the colonies; for example, some of those populations exhibit increased “grooming behaviour”, whilst others apparently have been able to detect and clear out brood infected by Varroa mites, … Others show combinations of these traits. (Locke, 2015) Of course it should not be forgotten that these honey bee colonies also remain smaller than honey bee colonies at a beekeeper’s apiary – the volume of a tree cavity is limited where beekeepers can increase the volume of their beehives as they wish – and that they are not prevented to swarm; both being factors limiting the amount of Varroa mites in the colony.
The “conservation by utilization” (discussed earlier) can be considered as “ex situ conservation”, in which organisms are preserved by humans in an artificial environment, as is done with numerous animal and plant species in zoos, botanical gardens, etc. In case of our Dark bee it concerns beehives instead of tree cavities, the environment in which worker bees forage for food remains the same as in which wild worker bees would do. “Conservation through rewilding” which is similar to “conservation in situ”, is the purest variety of conservation. For DarkBee.org, this is a goal to pursue, because fully exposing Dark bees to natural selection will provide opportunities to learn even more about these amazing creatures, perhaps also things that are useful for further improving sustainability of our beekeeping. (Blacquière et al ., 2019; Requier et al. , 2019 & Mikheyev et al. , 2015) In order to create a wild population of Dark bees, it would be sufficient, once a conservation area is reality, to install nest boxes for honey bees at the core of that conservation area and to release swarms of Dark bees.
In the long term, the aim is to create a network of conservation areas for the Dark bees, of which each conservation area would have its own mating station and its own locally adapted population of Dark bees (minimum of 150 Dark bee colonies), which may even be partly living in the wild, partly living in beehives. These local populations would then be subpopulations of 1 large metapopulation. This means, among other things, that the local populations fulfill a back-up function for each other: if a local population is not doing well (for example due to unwanted hybridization or death), then this population can be strengthened by translocation of Dark bee colonies from neighboring subpopulations.
Within a metapopulation, there is room for genetic exchange between neighboring subpopulations, but this is small-scale: large enough to prevent inbreeding depressions, small enough to prevent outbreeding depressions, as both can be problematic. (Zayed, 2009; Peer & Taborsky, 2005) Natural dispersion of honey bee colonies from one subpopulation to another would unfortunately be impossible in practice, since a swarm of honey bees is unable to move from one subpopulation to another on its own as long as the subpopulations are further than a few kilometers apart from each other. Translocation therefore offers a solution: Dark bee colonies chosen to disperse are moved by humans from one subpopulation to another. (Mergeay, 2017) The metapopulation concept is a key element in modern nature conservation and is applied in conservation programs of numerous plant and animal species; its usefulness cannot be overestimated. (Akcakaya et al., 2006)
These conservation areas can grow over time, just as new conservation areas can be found. In the search for locations to build a conservation area / mating station, it is important to get as little as possible into conflict with the already established mating stations since they are all being maintained for non-native honey bees. An attempt should be made to stay away from those mating stations as much as possible. The same applies to locations with a lot of houses or agricultural activity in order to avoid genetic pollution. After all, many beekeepers keep their beehives at home or at a pasture of a farmer for example. Avoiding would be in the interest of both the mating stations for Dark bees and the other mating stations.
In order to further minimize the risk of genetic pollution, it is important that no or as few as possible honey bee colonies – or at least drones – of a non-native honey bee are present in the vicinity of the mating station. This can be achieved by freely offering larvae from Dark breeding colonies to beekeepers near the mating station and/or asking them to destroy the drone brood of their non-dark colonies (which is also a biotechnical Varroa treatment). Finally, the location of the mating station must of course also be rich in forage resources. Taking everything into account, it sounds very difficult to achieve, though there are opportunities as well in Belgium as well as in the Netherlands.
Funny fact, such conservation areas, and especially the rewilding zones inside, also form unique locations where one could do natural beekeeping with the Dark bee. After all, one should no longer be afraid that a young Dark queen, which would fly out at his home apiary for mating, would mate with non-Dark drones. In this way, local young queens, born from swarm cells, can simply be mated locally. To be able to promote this home apiary mating, it would be important to continue to work on the expansion of the rewilding zone, and therefore of the entire conservation area.
The first subpopulation that is built up within this future-oriented metapopulation is located in the Flemish Kempen, for which Dark bees from the remaining Chimay population are used. Dark bees from Texel are reserved for more northern regions.
There is of course the awareness that this is a very ambitious goal requiring time to be achieved; some may even immediately put on the label “impossible”. However, this is the ultimate conservation project that DarkBee.org stands for; a project that secures the future of our native honey bee, the key to sustainable beekeeping. Let us try together to realize this wild dream!
AKCAKAYA, HR; MILLS, G. & DONCASTER, CP 2006. Key Topics in Conservation Biology.
BLACQUIERE, T .; BOOT, W .; CALIS, J .; MORO, A .; NEUMANN, P. & PANZIERA, D. 2019. Darwinian black box selection for resistance to settled invasive Varroa destructor parasites in honey bees. Biological Invasions. 21: 2519 – 2528.