Worker ants, which are sterile females, function as the primary workforce for the colony, handling tasks like nest maintenance, brood care, and foraging. Regarding their feeding habits, a worker ant both eats and carries food, utilizing a unique biological adaptation that prioritizes the colony’s needs. The food a forager collects is partitioned between the ant’s personal energy requirements and the collective sustenance of all nestmates. This specialized system allows the colony to function as an efficient unit for resource gathering and distribution.
The Worker Ant Diet
Worker ants forage for two distinct types of nutrients: carbohydrates and proteins. Carbohydrates, typically sugars, serve as the fuel source for adult workers, providing energy for movement and nest construction. These sugars are acquired from sources like plant nectar, tree sap, or honeydew (sugary excretions of sap-feeding insects).
Protein and lipid-rich foods are collected primarily to support the growth of the colony’s reproductive members and larvae. Foragers seek out dead or live insects, seeds, and other high-protein material to carry back to the nest.
Adult ants cannot ingest these solid proteins directly, as their digestive systems require liquid food. Larvae process this solid food by externally digesting the material and converting it into a liquid form that adults can consume and distribute.
How Workers Consume and Carry Food
The worker ant’s ability to feed itself and transport resources is facilitated by a dual digestive system involving two distinct “stomachs.” The true stomach, or midgut, is where the ant’s personal digestion occurs, breaking down liquid food to power the individual worker. The ant’s mouthparts include an infrabuccal plate, a filtering mechanism that ensures only liquids pass to the digestive tract while solid particles are filtered out.
The second stomach, known as the crop or “social stomach,” is an organ used solely for the storage and transport of undigested liquid food. This reservoir holds the majority of the foraged liquid until the worker returns to the nest.
A specialized muscular valve called the proventriculus controls the passage of material between the crop and the midgut. This valve ensures that the food intended for the colony remains separate from the ant’s personal digestive process.
Feeding the Colony Through Trophallaxis
The final step in the worker ant’s food cycle is the distribution of the stored liquid via trophallaxis. Trophallaxis is a mouth-to-mouth exchange where a forager regurgitates a droplet of liquid from its social stomach directly to a nestmate, such as another worker, a larva, or the queen. This behavior is the primary mechanism for sharing nutrients with immobile colony members, such as the queen, who requires a constant supply of protein to produce eggs.
The shared fluid contains chemical compounds and pheromones that are transferred throughout the colony. This chemical exchange helps maintain a uniform colony odor, which is important for nestmate recognition and social cohesion.
Trophallaxis also plays a role in social immunity by distributing beneficial antimicrobial substances, increasing the colony’s disease resistance. The collective function of all workers’ crops is central to the colony’s survival.