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Understanding Bee Breeding

Thanks to work carried out by our Chairman in his apiaries, which inspired other members to follow his example, GBBG has made progress in breeding a better bee. Progress because, without loss of honey yields, we now have a strain of bees which is less aggressive during hive manipulation.

At the same time we have not reached the ultimate in bee improvement. We have not yet reached a situation where a beekeeper supplied with a quiet queen can be guaranteed that the next generation of queens raised by him/herself will be as good to handle, although this is to a large extent due to queens mating with the wrong drones.

In addition other aspects such as resistance to Varroa and associated disease are also high on our list of desirable characters for breeding.

To date our methods of selection are empirical and will continue to be so for some time to come. This method is safe but somewhat slower than scientific methodology / applied-genetics. The latter requires funding (e.g. government) for academic input (available in several EU countries but not in Ireland).

We would be justified in asking: Why does our method work, and can genetics explain or extrapolate a successful outcome?

Empirical methods of breeding animals and plants have been in use from prehistoric times long before genetics became established as a science, in many instances as in beekeeping it is still used today.

Can Genetics predict a Successful Outcome? The answer is yes.

Bees like all other organisms are subject to control by genes and environmental factors.

This point is easy to illustrate: In the honey bee unfertilised eggs develop into males, fertilised eggs develop into females. This is purely the function of genes.

When a fertilised egg develops, under certain nutritional conditions, either into a queen or a worker this is environment impinging on the genetic endowment.

From this we can conclude that the honey bee is subject to much plasticity and that in the course of selection we must allow for necessary environmental effects. Without the presence of varroa we cannot select for resistance to the parasite.

The characters mentioned above which we hope to tease out in our breeding programme can be classified as behavioural, and as such, inevitably depend on environmental conditions.

As already mentioned above the Varroa infestation is environmental. We would be looking for a genetic character, which will be stimulated to react to the presence of the parasite. One way of selecting for Varroa resistance is to select a bee which will uncap infected brood cells and remove the damaged larvae. We already know from the literature that uncapping and cleaning cells are separately inherited, therefore controlled by different genes.

Behavioural characters (BeCh) are usually controlled by sets of genes often described as polygenes. This is true also for ‘straightforward’ metric characters (MC) examples of which are known to us in wing morphometry.

In the scientific literature characters of this type are dealt with under the heading of Quantitative Genetics (a large and important field in genetics which requires specialised knowledge in mathematics and statistics).

Gregor Mendel dealt in his experiments with major genes. These are single units which exert a visible effect.Known genes of this type described in the literature on bees include: Wrinkled wings (wr), garnet eye colour (g) (described by Laidlaw, el-Banby & Tucker).

The polygenes in which we are interested differ from the above only quantitatively. In a polygenic set the effect of each individual gene is not sufficient to be recognised.

Since these ‘minor’ genes are linked in some way so that they can be inherited as a group, their effect is as good as a ‘major gene’, they can be interspersed with other unrelated but recognisable characters. Such as the number of bristles on tergites, with the result that when bristles are targeted for selection they can also effect a physiological or behavioural character of the insect. (Much of this type of research has been carried out on the fruit fly Drosophila).

Needless to say that for this reason we have to be careful how we handle and interpret our wing morphometry in conjunction with the rest of our breeding programme.

Jacob Kahn