A queen honey bee. Image from wired.com.
Queens are the capstone of any beehive; only a single actively reproducing queen is present in a colony at a time and acts as the hive’s only means of reproduction under normal circumstances. Almost all workers in a hive the daughters of the queen and the drones produced in the hive are the queen’s clones. It is this degree of genetic similarity that drives the overwhelming kin selection pressure that forge the hive into a (usually) indivisible darwinian unit.
Queen bees exude a cocktail of pheromones that have so far been determined to attract workers immediately around the queen as well as drones during their flights and prevent workers from reproducing at the individual (worker egg-laying) and colony (swarming) level. While the queen emits at least 10 chemicals simultaneously, none have an effect except in the presence of queen mandibular pheromone (QMP) (Keeling et al 2003).
A queen elicits a retinue response from workers, one of many functions of QMP. Image from ucanr.edu.
The exact role and function of queen pheromones is not well understood and the subject of enormous research. It has been hypothesized that levels of QMP decrease as a queen ages and eventually pass a threshold that signals the colony to reproduce. This process would have to coincide with increasing worker populations such that the queen’s signaling decreases past the threshold point at the same time workers become overcrowded in the nest. However upon experimental analysis QMP levels appear to remain constant throughout the life of a queen, leaving the queen’s (almost certainly critical) role in swarm signalling a mystery (Seeley et al 1981).
Queens are the only members of a beehive that are capable of reproduction under normal circumstances. Due to this unusual situation, special reproductive methods are employed by the queen and the drones it mates with to ensure the queen can be a constant source of healthy offspring. Broods are reared such that the hive houses large populations of sexually mature drones and multiple queens twice a year, with the most of both these casts being present in the spring and a smaller number being present in the late summer. The queens and drones from the same hive do not typically mate and so inter-hive congregation sites are established for reproduction (see Hive Dynamics, and Drones, Mating Behavior). (Winston 207)
A queen usually becomes pregnant with the sperm of 7-17 drones, consequently housing tens or hundreds of millions of sperm within its reproductive tract. A queen usually lays at most 1500 eggs in a day, totalling around 175,000-200,000 eggs annually and more than 500,000 over the queen's approximately four year lifespan . These number imply intense postcopulatory sperm competition within the queen. WIthin the queen an organ known as the spermatheca houses the sperm from each drone mostly without mixing, to ensure a diversity of male genetic material in the brood to be. They do mix to some extent, however, to ensure that at any given point no father drone has a monopoly on the current worker population. When the queen’s female offspring have begun to finish gestation roughly three days after they have been fertilized the queen is lifted up and shaken by the attendant workers to shake free the offspring, which are then deposited in cells situated in the comb where they then become differentiated into either queens or workers and develop accordingly. Male offspring are not fertilized but are deposited into the comb directly to develop into drones (Winston 211).