Honeybee’s are very complex and unusual organisms. This makes honeybee breeding one of the most complex areas of livestock improvement, due to their haplodiploidy nature. Compared to the likes of sheep and cattle, the unit of selection is not made on an individual, but on the hive itself. At Betta Bees Research we maintain a closed breeding population by using instrumental insemination. This allows us to control matings and select for traits which are most desirable for our shareholders and customers.
In a closed population, we maintain our evaluation cohort that has a closed gene pool.
The following is an outline of how we do this:
1. Every year up to 200 colonies are evaluated under very different environmental
2. From those 200, 25-30 of the top preforming queens from those colonies are selected to raise virgins/drones for the next years evaluation cohort.
3. These 200 virgins and instrumentally inseminated using a pool of homogenized semen from the selected drone colonies. This means that any difference we see between the evaluation colonies is due to queens alone (as all the evaluation colonies have the same drone fathers).
By running a closed population breeding programme we are able to effectively select the traits we want and breed out the traits we don’t want. We are also able to maintain these traits within the population. Without a closed population to maintain these traits they would be lost or significantly diluted within 2 to 3 generations of open free mating.
Closed Population Breeding
Issues with closed populations
However, because of the way honeybees determine sex, closed population can quickly result in inbreeding. This is due to the loss of the alleles that determine sex, known as the CSD allele or the sex determining allele. Traditionally, this has meant you need to run very large breeding programmes with a minimum of 50 breeder colonies to give the programme some longevity. This however, is very costly to do. You also needed to introduce a lot of new genetic material to introduce CSD alleles that have been lost or were never present. This could also affect what you are trying
to achieve in the programme as undesirable traits could be introduced.
By working with Genetics Otago at the University of Otago we have developed a solution to this inbreeding problem. Genetics Otago developed a molecular test that allows us to screen our colonies to see which CSD alleles we have within the closed population. This means we can manage the CSD alleles and ensure we do not lose any of them.
The result of this is that we can:
1 Run the breeding programme with far fewer hives and breeders, thus reducing costs.
2 The programme should be able to last indefinitely as we avoid inbreeding by managing the CSD alleles.
When we introduce any new genetic material, from queens or semen, we can see if this will be worthwhile in introducing CSD alleles that we don’t have in our closed population.
We may do this to:
3 Introduce a new CSD allele.
4 Introduce a desirable trait.
5 Boost a desirable trait.
6 Increase vigor.
However, introducing new genetic material may have unforeseen negative impacts on the population. To minimize the possibility of negative impacts we fully assess all stock prior to introduction. This assessment may take 1 to 2 years and includes.
1 Conducting an initial assessment. If the queen passes this assessment and we believe she may have something to offer, we go to the next step.
2 We raise a number of daughter queens from this queen and instrumentally inseminate them with pooled semen from our breeding line.
These daughter queens are evaluated throughout a season alongside our breeding programme. If any of the queens score highly enough we would then introduce that daughter queen into our breeding programme.
Introduction of New Genetic Material
The Italian Honey Bee
The Italian Honey Bee (Apis mellifera ligustica) originated from Italy and is the most commonly used bee in New Zealand and around the world. Compared to other honeybee sub-species, the Italian bee is smaller and lighter in colour with yellow bands on their body and a slightly longer tongue. They are known for being good breeders due to their tendency for early build up in the spring and gentle temperament. Italian bees are less inclined to swarm, but are inclined to rob other hives in times of dearth.
Click here to found out how you can help us protect the future and wellbeing of the New Zealand honeybee.