Their Primary Food Source
Leafcutter ants do not consume the green leaves they are often seen carrying; instead, their entire diet consists of a specific type of fungus, Leucoagaricus gongylophorus, which they cultivate within their underground nests. The ants feed on specialized, nutrient-rich structures produced by the fungus.
The fungus breaks down complex carbohydrates in plant material, making nutrients digestible for the ants. Inside the nest, the fungus forms a whitish, spongy mass that fills large chambers. Worker ants regularly inspect and tend to this fungal garden, ensuring its optimal growth.
Gathering Plant Material
Leafcutter ants gather plant material not for consumption, but to feed their cultivated fungus. Leaves, flowers, grasses, and fruits serve as a substrate for the fungal garden, providing necessary nutrients for its growth.
Ants embark on foraging expeditions, forming long trails that can extend for hundreds of feet from their nest. Using their sharp mandibles, worker ants cut crescent-shaped pieces from leaves. They carry these fragments over their heads, resembling tiny green sails, back to their underground colony.
Upon returning to the nest, smaller worker ants process the collected plant material. They chew the leaf fragments into a pulp, which is then incorporated into the fungal garden. This continuous supply of fresh plant matter is vital for the fungus.
The Symbiotic Relationship
The relationship between leafcutter ants and their fungus is a mutualistic symbiosis, where both organisms benefit from the interaction. The ants provide the fungus with a constant supply of prepared plant material, free from competing microbes. They meticulously clean the plant substrate and inoculate it with fungal mycelia.
In return, the fungus digests complex cellulose and other compounds in the plant material, which the ants cannot process. The fungus produces unique, swollen structures called gongylidia, rich in carbohydrates and proteins. These gongylidia are the primary food source for all ant castes, including larvae, workers, and the queen.
This intricate partnership is so complete that neither leafcutter ants nor Leucoagaricus gongylophorus fungus can survive independently in nature. The ants protect the fungus from pests and pathogens, maintain optimal humidity and temperature within garden chambers, and use their own fecal droplets to fertilize the fungus. This co-evolution has resulted in a specialized, interdependent system that supports vast ant colonies.