The biological process that creates a male bee, known as a drone, is an exception to the reproductive norms seen in most animal species. Unlike humans and other mammals, the drone develops from an egg that has not been fertilized. This unique method means the male bee has a mother but technically no father. This system of sex determination is fundamental to the structure and survival of the entire bee colony.
The Haplodiploidy Mechanism
The genetic foundation for male bee production is haplodiploidy, a system governing sex determination across the order Hymenoptera, including bees, ants, and wasps. This mechanism dictates that the number of chromosome sets an individual possesses determines its sex. Female bees, including workers and queens, develop from fertilized eggs and are diploid, possessing two complete sets of chromosomes.
A female bee has 32 chromosomes, 16 inherited from each parent. Male bees develop from unfertilized eggs through a process known as arrhenotoky. Since the egg is not fertilized, the drone receives only one set of chromosomes from its mother, making it a haploid organism with 16 total chromosomes. This difference in chromosome count is the defining factor for the bee’s sex.
The haploid nature of the male bee has consequences for its genetic makeup and lineage. Because they possess only one set of chromosomes, all sperm a drone produces are genetically identical. A male bee has a mother and a grandfather, but he cannot have a father. He can only pass his genes to daughters (queens and workers) if he mates successfully, driving the close relatedness within the hive.
How the Queen Determines Gender
The queen bee controls the sex of each egg she lays. She stores sperm from her mating flight, which may involve dozens of drones, in a specialized internal organ called the spermatheca. This sperm supply is sufficient to fertilize all the eggs she will lay for the rest of her life.
When the queen is ready to lay an egg, she decides whether to release sperm from the spermatheca as the egg passes down her oviduct. If she releases sperm, the egg is fertilized, resulting in a diploid female bee. If she withholds the sperm, the egg remains unfertilized and develops into a haploid male bee.
The queen receives cues from worker bees and the physical structure of the honeycomb to guide her decision. Worker bees construct two distinct sizes of brood cells: smaller cells for female workers and larger cells for males. As the queen inspects a cell, she gauges its diameter. If she encounters a large drone cell, she withholds sperm, laying an unfertilized egg that will become a drone.
The Function and Fate of Drones
The haploid drone’s existence is dedicated to a single purpose: reproduction. Their role is to mate with a new queen from a different colony to ensure genetic diversity across the bee population. Drones are physically larger than worker bees, possess enormous eyes to spot a queen during flight, and lack the ability to perform hive maintenance tasks.
A drone has no stinger, cannot forage for nectar or pollen, and depends entirely on worker bees for food and warmth. They spend their days congregating in specific areas high in the air, known as drone congregation areas, awaiting the arrival of a virgin queen. Mating occurs in flight, and the act is fatal for the drone.
Upon successful copulation, the drone’s reproductive organ, the endophallus, is ripped from his body, and he dies immediately afterward. For the drones who do not successfully mate, their fate is determined by the changing seasons. As resources become scarce in late autumn or winter, the worker bees forcibly evict the drones from the hive. Because they cannot forage or protect themselves, these expelled males quickly perish from cold and starvation.