Rare Virgin Birth Gene Identified in Cape Bees
The virgin birth abilities of Cape bees has been known for over one hundred years, and scientists have been searching for the gene that makes it possible for the past thirty years.
The Cape bee (Apis mellifera capensis), which is a subspecies of the honeybee, is native only to the southern tip of South Africa. It may sound like a miracle that a honeybee is capable of reproducing through virgin birth. But the Cape bees develop this ability once the hive’s queen bee dies. This is the only time they are able to reproduce in this way.
Scientists have determined the gene that makes this unique ability possible for Cape bees. A study was carried out, led by behavioral geneticist Professor Benjamin Oldroyd of the School of Life and Environmental Sciences at the University of Sydney, Australia. They compared genetic sequences, or ‘genomes’ of Cape bees with those of other honeybee subspecies. He and his colleagues solved the mystery and learned that it is on chromosome 11, identifying the gene responsible for the virgin births and naming it GB45239.
This short 0:28-second video shows Cape bees in a colony:
The way it works is that female worker bees lay eggs that develop into female bees. Since worker bees are unable to mate, these eggs are unfertilized by males. Therefore, this is a form of asexual reproduction, known as ‘thelytoky.’
These Cape bees are literally creating clones, and by producing female bees, they can give birth to a new queen for their colony. This ensures the survival of the colony. The ability to produce daughters by asexual means is called “thelytokous parthenogenesis.” The Cape honeybee is the only known honeybee that can do this, perhaps because her ovaries are larger than in worker bees of other species, and more readily able to produce queen pheromones. This lets them assert reproductive dominance in a colony.
These same traits lead to an aggressive tendency to invade foreign colonies, reproduce in them and persuade the host colony worker bees to feed their larvae, which expresses as ‘social parasitism.’ Cape honeybee social parasite behavior causes 10,000 colonies of commercial beehives to die every year in South Africa. For these reasons, the Cape honeybee would not be welcome in Australia.
In contrast, worker bees from other honeybee subspecies are only capable of producing male bees, or drones. These must then fly off to mate with a queen bee from another colony, so they are of no help to their own colony. In this subspecies, the male bee, already considered quite useless, becomes redundant.
Unfortunately, these Cape bees are aggressive. Instead of being of a cooperative nature, Cape honeybee colonies have much conflict and competition. According to Professor Oldroyd, this is because every worker bee can be genetically reincarnated as the next queen bee. When a queen is lost, the worker bees compete and fight to become the mother of the next queen.
Professor Oldroyd says this is all very exciting. There are vast implications if we could control a switch that allows animals to asexually reproduce. For many pests and species such as fire ants that are thelytokous, this could potentially help create a genetic ‘off switch’ to turn off their asexual reproduction, although a different gene may be involved to the one that has been found in Cape bees.
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