Bee breeding techniques - overview
The ability to control mating between the males and the females is central to any breeding programme and yet controlling the mating process of honey bees is difficult. It is normal for a queen to mate with as many as 15 drones and these may come from colonies outside the control of the bee breeder. Mating takes place in the air, normally in established drone congregation areas. Maximum attraction of drones to a queen takes place at heights of 15-25 metres in the air. The reason that honey bees mate in this way is that to keep the number of drones (who are basically expensive passengers in the colony) down to a manageable number they only have half the number of chromosomes (16) that are present in the females (32). The consequence of this is that it is very easy to lose genetic diversity in honey bees. This diversity is essential for evolution and long term species species survival. Some of the problems arising in the United States with CCD are thought to be because the honey bee was not indigenous. Consequently, the genetic diversity of the imported bees was low - and is now too low to be able to manage the challenges that the bees are now facing. Queens mating with a large number of drones from as many different and distant colonies as possible will maintain genetic diversity and thus species fitness.
Many attempts have been made to mate queens in cages or confined areas without success. For natural mating to be controlled, all drones that are not of the desired type have to be excluded from the mating area. This usually means taking both queens and drones temporarily to a new mating area where there are not already established drone congregations and establishing drone congregations that are composed only of the desired strain or race of honey bee. Isolated places such as mountains and islands have been used in controlled mating. Islands have been the most successful in obtaining pure matings as honey bees will not fly across large stretches of water. However, the island must not have an indigenous honey bee population (unless it is the desired type) and must be at least 5 km away from land to be sufficiently isolated. Mountain mating sites have also been successfully used but here the colonies need to be a minimum 15km from any other colonies. These circumstances are not common, so alternative ideas have been examined.
Flooding an area with drones of the desired type in an effort to reduce the influence of undesirable matings has been found to be effective in some places. This technique is probably the most accessible to the majority of beekeepers, requiring the least investment in complicated equipment, regulation or transport infrastructure and allows some heterozygosity to remain in the population. The technique works best if a group of people in a given area agree to share queens and drones, have a clear idea of what they want to gain from a breeding programme and are able to persuade all or most members of the community to participate in the scheme. In a variation on this theme sometimes a degree of temporal isolation can be achieved by rearing queens and drones either very early or very late when the majority of other drones and queens have reduced breeding activity.
Instrumental insemination is the artificial transfer of semen to the queen's oviducts where it will migrate to the spermatheca (the queens' long term storage organ for sperm). Sperm is collected manually from sexually mature drones using a glass tipped syringe and the queen is inseminated when narcotised by carbon dioxide using special equipment that constrains the queen, opens the way into her oviduct and delivers a micro-metered quantity of semen.
However, instrumental insemination is rarely a useful technique in developing countries. It is too expensive and the offspring can not be kept true to type afterwards by natural mating. It is a specialist field that is unsuitable for most beekeepers.
There is some potential for developing less defensive and more productive strains of tropical bees. It would be quite possible to do this and results in unselected populations can be very quick. However, it is important that a survey of the total population and their behavioural characteristics is carried out before bee breeding projects are undertaken. It is very easy to loose genetic material that no-one ever knew was there, was useful or might be wanted in the future. Once genetic material is lost it has gone for good. Extinction is for ever.
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- Author Bees for Development
- Publisher Bees for Development
- Published Date October 2016
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