A honey bee colony is a complex and highly organized society composed of three distinct types of adult bees: the queen, the drones, and the worker bees. While the queen is the sole reproductive female, the vast majority of the hive’s population, numbering in the tens of thousands, is composed of female worker bees. This unique social structure and the different roles within it are determined by a biological mechanism involving both genetics and nutrition.
The Worker Bee The Other Female
Worker bees are genetically female and develop from fertilized eggs, but they are functionally sterile. They are the smallest caste and form the bulk of the colony, often numbering between 10,000 and 40,000 individuals. Their sterility results from the diet they receive during the larval stage; unlike a queen larva fed an exclusive diet of royal jelly, a worker larva is switched to pollen and honey after the first few days. Furthermore, the queen releases pheromones that suppress the development of the workers’ ovaries, maintaining the reproductive division of labor.
The worker bee’s short life involves an age-based progression of duties that keeps the colony functioning. Young workers start with tasks inside the nest, such as cleaning cells, feeding the larvae, and constructing beeswax comb. As they age, their duties progress to processing food, guarding the hive entrance, and eventually foraging outside for nectar, pollen, water, and propolis.
How Bee Sex is Determined
The mechanism that produces the different sexes within the honey bee colony is called haplodiploidy, a system of sex determination based on the number of chromosome sets an individual receives. Females, including both queens and workers, develop from fertilized eggs and are diploid, possessing two sets of chromosomes—one from the mother and one from the father. A female honey bee has 32 total chromosomes.
Males, known as drones, develop from unfertilized eggs and are haploid, meaning they possess only one set of chromosomes, inherited solely from their mother. A drone has 16 total chromosomes. The queen controls the sex of her offspring by choosing whether or not to fertilize an egg as she lays it.
This genetic system is regulated by a specific sequence on a chromosome called the complementary sex determiner (csd) gene. If a bee inherits two different versions (alleles) of the csd gene, it develops into a female. Conversely, inheriting only a single version of the csd gene results in a male.
The Life and Purpose of the Drone
The drone is the male honey bee, dedicated primarily to reproduction. Drones are larger than worker bees, with notably large eyes that assist in spotting a queen during flight. Unlike workers, drones lack a stinger and the necessary anatomical structures for foraging, such as pollen baskets or a honey stomach.
The drone’s sole function is to mate with a virgin queen from a different colony in designated aerial gathering spots called drone congregation areas. A successful mating is often fatal for the drone, as his reproductive organ and associated tissues are ripped away in the process. Drones that do not mate are eventually expelled from the hive by workers when resources become scarce in the autumn.