The queen ant serves as the colony’s reproductive engine, laying all the eggs that develop into workers, soldiers, and future reproductive individuals. Her presence releases chemical signals, or pheromones, that organize the colony’s social structure and regulate the behavior of her offspring. While many assume an ant colony has only one queen, the actual number varies drastically across the more than 12,500 known ant species, fundamentally changing how the colony operates.
The Standard: Colonies with a Single Queen
The most common social structure observed in ants is called monogyny, defined by the presence of a single reproductive queen. This state is considered the ancestral condition from which other reproductive strategies have evolved. In a monogynous colony, the queen maintains her reproductive monopoly through the consistent release of pheromones, which suppress the reproductive development of female worker ants.
The queen’s dominance can also involve direct aggression toward potential rivals. This structure creates intense genetic relatedness within the colony, as all workers share the same mother. The trade-off for this single-queen model is the vulnerability of the colony; if the queen dies prematurely, the entire colony will eventually collapse.
Colonies with Multiple Queens
While monogyny is the baseline, many successful ant species employ a strategy called polygyny, where colonies contain multiple reproductive queens. The number of queens can range from two to hundreds, as seen in species like the fire ant. Polygyny has evolved independently across the ant family tree, suggesting its advantages outweigh the cost of reduced genetic relatedness among nestmates.
The benefits of multiple queens include increased egg output, faster colony growth, and redundancy against the death of a single queen. A polygynous colony can recover quickly from environmental stress and maximize reproductive capacity. This structure is common in widespread, invasive species, such as the Argentine ant, which uses its multi-queen system to establish massive, highly dense colonies.
The Effect of Queen Number on Colony Strategy
The number of queens fundamentally dictates a colony’s overall behavioral strategy and ecological impact. Monogynous colonies, due to their high genetic relatedness, tend to be highly territorial and aggressive toward neighboring ant colonies. Their focus is on defending a defined territory and protecting the queen. This intense competition often limits the size and spread of these single-queen colonies.
In contrast, polygynous colonies often exhibit reduced aggression toward other nests of the same species, a phenomenon known as reduced nestmate recognition. This tolerance allows them to form vast, interconnected “supercolonies” that lack clear boundaries, enabling them to achieve far greater densities and biomass than monogynous species. Their strategy is one of rapid, expansive growth and dispersal, often making them opportunistic and invasive pests. These multi-queen colonies are also highly mobile, frequently splitting off into smaller fragments that carry queens and workers to quickly exploit new habitats.
How New Queens Are Produced and Integrated
The creation of a new queen begins when a female larva receives a specific diet and chemical cues during development. This enhanced nourishment causes the larva to develop into a winged, sexually mature female, known as an alate. Once mature, these alates participate in the “nuptial flight,” leaving the nest to mate with winged males from other colonies.
After mating, the newly fertilized queen sheds her wings and attempts to found a new colony. This process, called claustral founding, means she relies solely on stored energy reserves to rear her first batch of workers. Alternatively, some species, particularly polygynous ones, engage in dependent founding, where new queens leave the parent nest accompanied by workers or are adopted into an existing colony. While monogynous colonies generally reject or kill rival queens, polygynous colonies are much more accepting, allowing for the continuous integration of reproductive individuals.