The queen insect stands at the center of a complex society, serving as the biological anchor for the entire colony. Eusociality, the highest form of social organization in animals, relies on reproductive division of labor, with the queen being the specialized reproductive individual. She is morphologically distinct, typically possessing a larger body size and a highly developed abdomen to house her reproductive organs. Her specialized, life-long function is to ensure the perpetuation of the colony, making her the sole source of new life and dictating the colony’s existence.
The Engine of Reproduction
The primary occupation of a queen insect is mass egg production, a state known as high fecundity. The queen’s extended lifespan, which can last up to 30 years in some ant species, ensures a continuous supply of offspring, sustaining the colony for decades. Her body is highly adapted for this purpose, with greatly enlarged ovaries compared to sterile female workers.
In Hymenoptera (ants, bees, and wasps), the queen controls the sex of her offspring through a system called haplodiploidy. She stores sperm from her mating flight in a specialized organ called the spermatheca. When laying an egg, the queen chooses whether to fertilize it with stored sperm, resulting in a diploid female (worker or new queen), or to lay it unfertilized, resulting in a haploid male (drone).
Chemical Command and Caste Control
The queen governs the colony not through direct physical force but through a continuous broadcast of chemical signals known as queen pheromones. These complex chemical blends are distributed throughout the nest, primarily via contact between the workers who groom and feed the queen. The pheromones function as a form of social communication, influencing the behavior and physiology of thousands of colony members.
One of the main functions of these pheromones is the suppression of worker reproduction. For example, in honeybees, the Queen Mandibular Pheromone inhibits the workers from developing their own ovaries and rearing new queens, ensuring the reigning queen’s reproductive monopoly. When the concentration of this pheromone drops, such as when the queen ages or dies, the workers recognize the signal and begin to construct specialized cells to rear new queens.
The chemical signals also regulate the daily activities of the colony, coordinating tasks like foraging, nest construction, and brood care. In termites, specific inhibitory pheromones act directly on developing nymphs, preventing them from differentiating into replacement reproductives. This chemical communication maintains the social order and ensures that all individuals perform their designated caste roles.
From Nuptial Flight to Colony Foundation
The queen’s specialized life begins with the nuptial flight, a synchronized mating event where virgin queens and males, known as alates, leave their parent colony. This flight is a high-risk endeavor, designed to promote outcrossing and genetic diversity by mating with individuals from other colonies. The virgin queen may mate with multiple males during this short period, storing the collected sperm in her spermatheca.
Once successfully mated, the female sheds her wings, which are no longer needed, and seeks a location to establish a new nest. The first phase of colony establishment varies between species, often categorized into two types. In claustral founding, the queen seals herself off and relies entirely on metabolizing her stored body reserves, including the wing muscles, to nourish the first clutch of eggs.
In semi-claustral founding, the queen must leave the nest periodically to forage for food to sustain herself and her first brood. In either case, the queen performs all initial worker tasks, such as egg-laying and larval care, until the first generation of sterile workers hatches and takes over the labor. Once the workers emerge, the queen transitions to her life-long role as an egg-laying machine.
Variations in Social Structure
While the fundamental role of the queen is consistent across eusocial insects, the physical form and number of queens per colony can vary significantly. Monogyny describes a colony structure where only a single, fully reproductive queen is present, which is common in species like the honeybee. This structure results in a high degree of relatedness among colony members.
In contrast, polygyny is the presence of multiple functional queens within the same colony, a trait found in many ant and wasp species. Polygynous colonies can grow much larger and more quickly than monogynous ones, as they have several reproductive centers. The presence of multiple queens, however, sometimes leads to reduced individual fecundity due to competition and a lower average genetic relatedness among workers.
Termites present a unique variation, as their colonies are typically headed by a queen and a king, with the male remaining with the queen for repeat mating throughout their lives. The termite queen also exhibits extreme physogastry, a process where her abdomen swells enormously over time due to the massive development of her ovaries. This abdominal enlargement allows a mature queen to achieve incredible egg-laying rates, sometimes producing dozens of eggs every minute.