The Western honey bee, Apis mellifera, maintains its highly organized social structure through a unique reproductive system. Unlike most animal species, honey bees employ two distinct strategies. This dual approach, known as haplodiploidy, allows the colony to precisely control the sex of its offspring, which is foundational to their survival.
The queen bee is the central figure, serving as the sole reproductive female responsible for producing all colony members. The choice between sexual and asexual reproduction determines whether the resulting offspring will be female or male, ensuring the correct balance of workers and drones needed to sustain the hive.
How Sexual Reproduction Creates Female Bees
Sexual reproduction creates all female members of the colony, including sterile worker bees and reproductive queens. This process involves the fusion of two gametes: a haploid egg produced by the queen and a haploid sperm from a male drone. The resulting fertilized egg contains a full set of chromosomes, receiving one set from each parent.
This genetic state is known as diploidy, meaning the female offspring possess two copies of every chromosome. Female bees therefore have a complete genetic makeup derived from both a mother and a father. The queen selectively releases stored sperm to fertilize an egg as it travels down her oviduct, initiating the development of a female bee.
The ultimate fate of this diploid female—whether she develops into a worker or a queen—is determined by the care she receives, not genetics. Larvae destined to become queens are exclusively fed a protein-rich substance called royal jelly throughout their development. Female larvae that receive royal jelly for only a few days become the non-reproductive worker bees.
How Asexual Reproduction Creates Male Bees
Asexual reproduction in honey bees is a specialized form known as parthenogenesis, which is the only way male bees, called drones, are produced. This process occurs when the queen lays an egg that has not been fertilized by sperm. The unfertilized egg develops directly into a male bee.
Since the egg does not combine with a paternal gamete, the resulting drone possesses only a single set of chromosomes, a condition known as haploidy. All of the drone’s genetic material is inherited solely from its mother, the queen. This unique genetic state means that a drone has a mother but no father.
The drone’s haploid nature affects its ability to reproduce. It cannot have sons but passes its entire set of chromosomes to its daughters when mating with a queen.
The Queen Bee’s Reproductive Control
The reproductive flexibility of the honey bee colony is controlled by the queen’s ability to determine whether or not to fertilize an egg at the moment of laying. This precision is made possible by the spermatheca, a small, spherical sac located in her abdomen. During mating flights early in life, the queen mates with multiple drones and stores their collected sperm in this single organ for the rest of her lifespan.
As a queen prepares to lay an egg, she uses the size of the brood cell as a tactile cue to determine the egg’s gender. If she is laying in a smaller cell, she releases stored sperm from the spermatheca to fertilize the egg. This results in a diploid female.
If the queen encounters a larger cell, constructed specifically for a drone, she withholds the release of sperm. The egg passes unfertilized, leading to the development of a haploid male drone. This ability to choose the sex of each egg is the central regulatory mechanism that allows the queen to manage the colony’s social structure.