By Edward Hill North Kildare BKA
I always struggle with bee genetics.
In today’s world scientists are able to decode the genes of various plants and animals.
As humans, we are said to share 99% of our genes with chimpanzees.
Most species are unique, basically we all share genes from our parents.
Mothers contribute chromosomes from their eggs and fathers from their sperm, most of the animal kingdom operates on this principle. But honey bees are different and their approach to passing on chromosomes works differently and has different outcomes.
To start with let’s look at the Drone who is male, this always confuses people new to beekeeping.
- They have no father,
- They have only one grandfather,
- They can be fathers to daughters, granddaughters and grandsons,
- But they can’t have sons.
This is because Drones are born from an unfertilised egg laid by the Queen.
The egg is not fertilised by sperm from another Drone, in this case the Drone is referred to as being Haploid which is the technical term to say he has only one set of Chromosomes all from his mother.
This process of reproduction in honey bees from unfertilised eggs is referred to as parthenogenesis.
When the Queen lays an egg and it is fertilised with sperm from a Drone it will develop into a female bee and will either be a worker or a future Queen. These female honey bees are called diploids which means it has two complete sets of chromosomes one set from each parent.
This type of sex determination in honey bees is called haplodiploidy.
Now for the bit where it gets confusing:
There are a number of sub-species of honey bee such as Apis mellifera mellifera, Apis mellifera Ligustica, Apis mellifera caucasica, Apis mellifera carnica, Apis mellifera scutellata to name a few.
There are 44 sub species listed and they are all distinguished by their Phenotypes which literally means they have observable physical properties such as colour, size and behaviour.
They can all interbreed, if you look it up it is a bit more complicated, it always is.
The word genotype is used to describe the part of the genetic makeup of a cell, and therefore of any individual, which determines one of its characteristics (phenotype). The term was coined by the Danish botanist, plant physiologist and geneticist Wilhelm Johannsen in 1903. (Wikipedia)
A genotype is the unique genome of that organism which is its heritable identity, with Honey bees some have nearly the same genotype but different phenotypes but it’s not always like this as different phenotypes can reflect different genotypes, now you see why I get lost.
If you are studying genetics, scientists can now use DNA sequencing to identify different genotypes such as was completed in recent research here in Ireland relating to Apis mellifera mellifera. Here they were looking at Mitochondrial DNA to track the maternal lineage of bees submitted. Mitochondria are tiny organelles that are found in living cells, they release energy by burning sugar and oxygen, they may once have been free living bacteria but somewhere in time have been incorporated into living Cells.
These tiny mitochondria reproduce separately from the cell and divide when the cell divides but their DNA remains separate and does not change. So, they get passed along through the generations without their DNA changing and are not affected by mating with drones therefore they are passed through their mothers.
It was by studying these mitochondria that they discovered that a significant population of Apis mellifera mellifera remain in Ireland.
I hope I explained that bit right.
But what has this got to do with beekeeping, nothing if you are happy keeping bees and rearing a few queens from your own colonies each season. But if you want to breed bees rather than rear them, then this information and an understanding of it is crucial. We recently had a zoom discussion in North Kildare on bee improvement.
If trying to improve your bees we discussed the importance of keeping notes and from these we were selecting desirable traits from different colonies by scoring you bees out of five for Docility, resistance to disease, propensity to sting, amount of honey harvested, over wintering and speed of build-up of colony. The aim here was to encourage beekeepers to rear queens from those colonies that exhibited some or all of the above traits. It was all about performance measured throughout the season against specific traits and these can differ between aperies throughout the county or country.
The breeding of bees is a highly complex thing. This is usually carried out in laboratories to breed for specific traits such as hygienic behaviour, Varroa sensitive hygiene (VSH), Grooming behaviour, Short brood periods, longer living workers, temperament, Tracheal mite resistance, honey production and comb building.
But it’s not easy because the multiple mating habit of Queen Honey bees is a huge obstacle and cannot be controlled by the average beekeeper.
New methods have been adapted and Honey bees are now being instrumentally inseminated (II) which allows breeders to have complete control over both mating of the Queens and selection of the drones. There are advantages with instrumentally inseminated queens over natural mated queens, they can be mated by a single drone in a laboratory selected for specific traits and Queens can be mated with numerous drones to maintain genetic diversity. There are also disadvantages which I won’t go into here.
Most of our Queens mate naturally therefore we probably have a lot of mixing of genes from Apis mellifera mellifera with Buckfast or whatever else is in the area. Their offspring are referred to as mongrels and we all have them to some extent.
The issue with what is known as the Isle of Wight disease saw a lot of bees die out in the early 20th century and a lot of bees were imported from Europe to replace stocks. We now have a number of voluntary conservation areas (VCA) in Ireland where local beekeepers are encouraged to keep Amm’s like here in North Kildare.
But it is not mandatory, it can be very frustration for some beekeepers who have invested a lot of time and effort into improving their bees to discover that a local beekeeper has brought in different colonies of bees or imported queens who’s future sons will likely mate with future queens of the already established colonies.
So, what of the future, I believe the breeding of selective bees with specific traits is outside the scope of most beekeepers and will remain so for many years to come. But we can still rear queens from our colonies that exhibit the traits we would like to encourage. That will require the beekeeper to maintain diligent records and to co-operate with other local beekeepers.
It involves education, awareness of what is happening in your locality and a commitment to participate and be responsible. As was mentioned at our zoom meeting we need “Tolerance” by the local beekeepers of each other and that the bees produced must also be tolerant of the beekeeper so that they can be managed without being aggressive and sort out the errors inflicted upon them by an over enthusiastic beekeeper.
By Eddie Hill, North Kildare Beekeepers’ Association.