The Beekeeper’s Companion Since 1861
icon of list

Cover Story

Honey Bee Genetics

- October 1, 2015 - Peter Loring Borst - (excerpt)

Honey Bee

An exact determination of the laws of heredity will probably work more change in man’s outlook on the world, and in his power over nature, than any other advance in natural knowledge that can be foreseen (Bateson, 1900).

The idea of genetics came about before anyone really knew what a gene, if there were such a thing, might be. The breakthroughs that contributed to the concept occurred in the 1800s. Three men were critical in forming the new ideas: Mendel, Darwin and Dzierzon. If they had been communicating as freely as we are now, the ideas might have developed more quickly. Mendel is famous for his studies with pea plants; it is less well known that he also experimented with bees.

People understood that heredity was significant in all the known plants and animals. Darwin took the ideas of breeding and heredity and applied them to the question of evolution. He realized that different species were related, despite not being able to breed with each other. Could there be common ancestors from which different species descended? Dzierzon showed that the male honey bee arose when an egg grew up without being fertilized. In other words, without the genetic contribution from a father, no female bees would develop. These three discoveries laid the ground for our later understanding of honey bee genetics.

I have proposed the terms ‘gene’ and ‘genotype’… to be used in the science of genetics. The ‘gene’ is nothing but a very applicable little word, easily combined with others, and hence it may be useful as an expression for the ‘unit-factors’, ‘elements’ or ‘allelomorphs’ in the gametes, demonstrated by modern Mendelian researches (Johannsen, 1911).

Breeding of animals has been going on for millennia, of course, without anyone knowing the underlying mechanisms. Most of the plants and animals we enjoy now were “domesticated” in the distant past. Probably, people thought of breeding bees long before they had any idea how to proceed. The first real thrust in bee breeding was simply to find out what was already out there and pick from that to find the most suitable varieties. This led to the changeover in the United States from the traditional European black bee to the use of Italian bees. These had a reputation of being more manageable and resistant to brood disease. Bee researcher Walter Rothenbuhler stated in 1958: “It must be concluded that importation of races, from about 1860 to perhaps 1910, served to provide better bees for beekeepers in this country.”
At the same time, the study of heredity and genetics interested biologists for other than economic reasons. The need for better breeding and the desire to expand our understanding of biology have worked hand in hand to bring us to where we are now. In 1910, Secretary of Agriculture James Wilson was invited to write an introduction to the American Breeders Magazine. In his short introduction, Wilson noted the important potential that lay in the new approach to animal and plant breeding:

The science of genetics is fundamental for all agriculture. By purely empirical methods breeders have brought certain of the domestic animals to a high state of development. But an exact and comprehensive knowledge of how these results have been attained, and may be attained again, is, in general, lacking. In the last decade definite knowledge of the laws of inheritance has made greater advance than in the entire previous history of mankind (Wilson, 1910).

Statement of the Problem
As beekeepers all know, breeding bees is not the same as breeding other livestock. One cannot simply select the sire and dam, on the basis of fine attributes, and propagate bees which closely resemble the parents, bearing the best characters of each. Early writers promoted the idea of “breeding from the best” – choosing colonies that excelled in one way or another and raising daughters from those. This was certainly an improvement on simply relying on swarms to increase one’s holdings.

In the 1880s, Gilbert Doolittle, of Borodino NY, perfected a technique for propagating queens from selected colonies. His method forms the basis of queen production today. It consists of moving newly hatched bee larvae from worker cells into preformed queen cells so that thousands of daughter queens can be raised from a selected breeder. Doolittle: “Right here I wish to say, that only the best of tested Queens should be used as Queen-mothers – Queens known to possess all the desirable requisites that make a good Queen.” Queen breeders were able to select for external characteristics such as color, but found other characters to be more elusive. One of the chief reasons for this is the lack of control over the male line.

This changed in the early twentieth century. In his 1932 USDA pamphlet, W. J. Nolan described the technique of using a pipette to take semen from selected drone bees and use it to inseminate queen bees. He announced: “The way has been opened for the investigator in any locality to keep pure stock of various races and strains as well as to develop special strains of the honeybee.” He acknowledged that this tool would remain in the hands of skilled technicians for the time being and commercial beekeepers would continue to use established methods.

About this same time, a highly ambitious and focused beekeeper was perfecting bee breeding along conventional lines. I am referring to the legendary Brother Adam, the Benedictine monk of Buckfast Abbey. Realizing the need for control over both the male and female genetic contributions, he established an isolated mating station in Dartmoor, an area of moorland in south Devon, England which was sufficiently far from any other hives. Brother Adam traveled throughout Europe and parts of Asia and Africa to find breeding stock to incorporate in his experiments. He is credited both with advancing our understanding of honey bee genetics and – of accelerating the demise of the native honey bees of the British Isles.

Into the 1950s
I already mentioned Walter Rothenbuhler. He was one of many people who focused intently on honey bee genetics. The list is long, but would have to include O. W. Park, Otto Mackensen, Friedrich Ruttner, Harry Laidlaw and Warwick Kerr, to name but a few. This last name will forever be associated with the most instructive example of a conventional breeding experiment which had monumental unforeseen consequences. Perhaps it is worth digressing a bit to discuss what was intended and what took place. Dr. Kerr rightly observed that the European bee never did well in the tropical regions such as Brazil. He reasoned that a more suitable honey bee could be found in Africa, situated as it was directly across the Atlantic from Brazil. After many false starts, African queen bees were brought to Brazil and what happened next is not clear. The story goes that the queens were unwittingly released, but it is just as likely that queens were distributed by the researchers. In any case, they thrived and multiplied, and in a few decades expanded their territory from Argentina to the United States. The bees are definitely vigorous, and industrious, but with an excessive tendency to go into stinging frenzies, sometimes killing livestock in the vicinity of the hives.
However, the most important lesson is one of genetics and heredity – learned the hard way. Kerr and his colleagues hoped African and European bees would mate and produce a hybrid bee with showed the good characters of both subspecies. This idea was based on other experience, such as that of Brother Adam, who had crossed the Italian bee and the native bee of England, producing a vigorous hybrid with a calmer demeanor than the traditional English black bee. Actually, however, the crosses resulting from the introduction of the African bee into the Americas are mostly like the original African stock. Clearly, there was more to be learned about honey bee genetics.

This dramatic multiplication and spread of African genes is explained only by the assumption that their selective advantage was so overwhelming that they did not give the European genes the least chance. The Africanized bees proceeded 300 km and more per year, showing that they were adapted to the tropical environment of America as well as to that of Africa. For the Iberian bees, the 300 years after their importation was too short to develop efficient adaptations (Rinderer, 1986).

Understanding Honey Bee Genetics
The basics of honey bee genetics are not too different from what we learned in school: males contribute sperm, and females produce eggs. In ordinary meiosis, germ cells divide and the chromosome pairs separate. When a new life is formed, it receives one…,