The honeybee colony functions as a single, integrated biological unit known as a superorganism, where the survival of the group supersedes the individual. This collective life is centered on one female, the queen, who serves as the colony’s sole reproductive engine. The overwhelming majority of the thousands of bees within the hive are sterile female workers, dedicated to the queen’s support and the perpetuation of her lineage. The monarchy is maintained by specialized physical development, a sophisticated chemical control system, and active behavioral enforcement by the worker population. For the colony to thrive as a cohesive unit, the biological and social systems must ensure that only one female ever possesses the reproductive capacity.
The Specialized Making of a Queen
The potential to become a queen or a worker exists in every female egg, meaning the difference between the two castes is determined entirely by nutrition, not genetics. A female larva destined to become a queen is placed in a specialized, vertically oriented, and much larger peanut-shaped cell, contrasting with the small, horizontal hexagonal cells of workers. This large queen cell provides the space necessary for the larva to grow into a much larger adult bee with fully developed reproductive organs.
The key to this transformation is a continuous, exclusive diet of a protein-rich glandular secretion known as Royal Jelly. This unique food triggers the necessary hormonal changes to unlock the larva’s reproductive potential, leading to a much faster developmental timeline of just 16 days from egg to adult. Worker larvae receive Royal Jelly for only the first few days before their diet is switched to a mix of honey and pollen. This change in nutrition halts the development of their ovaries, resulting in sterile workers who take 21 days to complete their maturation.
Chemical Suppression: The Role of Queen Pheromones
The queen maintains her reproductive monopoly primarily through a chemical communication system that permeates the entire colony. The most significant element of this control is the Queen Mandibular Pheromone (QMP), a complex blend of fatty acids and aromatic compounds produced in the queen’s mandibular glands. A specific component, 9-oxo-2-decenoic acid (9ODA), is important in regulating worker behavior.
This pheromone is continuously distributed throughout the hive, first by the queen’s retinue—a group of worker bees that constantly attend to her, feeding and grooming her. These attendant bees then transfer the QMP to other workers through physical contact and food sharing, effectively broadcasting the queen’s presence and reproductive status. The QMP signal chemically suppresses the physical development of the worker bees.
One of the main effects of QMP is the inhibition of ovarian development in the sterile female workers, ensuring they remain incapable of laying eggs. The presence of a strong pheromone signal also prevents workers from constructing new queen cells. If the queen’s pheromone production wanes due to age or disease, or if the hive grows too large for the signal to reach every corner, the workers will instinctively begin to rear new queens.
Worker Policing and Maintaining the Monarchy
The final layer of defense against a rival queen is a behavioral mechanism known as worker policing, which involves the workers actively enforcing the single-queen rule. Even though QMP suppresses ovarian development, some workers may still activate their ovaries and attempt to lay unfertilized eggs, which would develop into male drones. Worker bees patrol the brood cells and use chemical cues to identify and destroy these worker-laid eggs. Studies show that approximately 98% of such eggs are killed and removed.
This action is considered a form of altruism for the colony, as the workers are genetically more related to the queen’s sons (their brothers) than to the sons of other workers (their nephews). Workers are able to distinguish non-queen eggs based on the absence of a unique hydrocarbon marker present on eggs laid by the queen. A worker’s shorter abdomen often forces her to lay eggs on the side of the cell rather than at the bottom, providing a visual cue for policing workers.
Worker policing also extends to the destruction of rival queen cells if a new queen successfully emerges and attempts to take over the hive. While QMP inhibits the construction of new queen cells, the policing workers will tear down and eliminate cells containing developing rivals if the colony perceives a threat to the established order. This combination of chemical suppression and active physical enforcement ensures that the colony maintains a single, productive reproductive female, preserving the integrity of the superorganism.