Leafcutter Ant (Atta cephalotes) Fact Sheet: Summary

Kingdom: Animalia

Phylum: Arthropoda

Class: Insecta

Order: Hymenoptera

Family: Formicidae

Genus: Atta

Species: Atta cephalotes

Range

Southern Mexico to Brazil

Habitat

Intact and human-modified wet tropical forests in the Neotropics

IUCN Status

Not assessed

CITES Appendix

Not listed

Populations in the Wild

No global estimates. Considered wide-ranging and abundant.

Activity Patterns

Colonies may be active during the day and at night. Some colonies nocturnal only. Rain and daytime parasitism by phorid flies likely suppress daytime activity, while warmer air and soil temperatures increase activity.

Nests

Huge underground nest structures that house millions of workers and immature ants. Interconnected system of tunnels and ball-shaped chambers. Larvae develop in wooly, sponge-like fungus gardens. Waste removed from fungal gardens and stored in separate refuse chambers.

Social Structure

Colonial insect with complex division of labor. A single long-lived queen and millions of sterile workers live together in an enormous underground nest. Workers cut and carry leaf fragments, clean and mulch leaves, tend symbiotic fungus gardens, care for queen and many larvae/pupae, and defend the nest, together with soldiers. Newly hatched workers perform tasks inside the nest (some outside, e.g., trail clearing), with older workers mainly active outside the nest.

Communication

Atta foragers communicate acoustically via a “stridulation organ” and chemically by trail and alarm pheromones.

Diet

Fresh plant material, mainly leaves, used to cultivate a specialized species of fungus (Leucoagaricus gongylophorus) in underground nest chambers. Ants and the fungus are dependent on each other for survival. Larvae, pupae, and adults feed on liquids produced in fungus’ bulbous tip structures (gongylidia). Plant sugars (nectars, saps) also appear to play a role in forager diets.

Predators

Army ants prey on leafcutter ant brood young. Birds, bats, and ground mammals feed on Atta queens searching for a nest site after mating.

Breeding System

Typically, a single reproductive queen that mates with up to 5 males before founding a new colony. Most worker offspring sterile, but colony produces a few thousand reproductive females and males each year, which disperse to mate.

Mating

During nuptial flights, males mate with females and die the same day. Females that survive the dispersal period establish new colonies. Queens never mate again; use stored sperm to fertilize eggs, until death.

Egg Laying

Queen lays a small number of viable eggs to found colony. After a few years, as a diverse labor caste system becomes established, queen can lay more than 25,000 eggs per day, on average, which may add up to as many as 150 million daughters over a lifetime.

Care of brood young

Small workers tend the eggs, larvae, and pupae developing in fungus garden chambers. During colony founding, queen provides initial care of fungus, eggs, and larvae. Her offspring workers later take on all care duties, allowing the queen to continuously lay eggs.

Typical Life Expectancy

Average colony life span for wild populations is thought to be about 8–9 years, though more research that tracks long-term survival of colonies is needed. Atta cephalotes queens are among the longest-lived insects. Typical life expectancy unknown but may live 10–20 years or longer.

Predators

Dispersing queens: birds, bats, and ground mammals (due to nutrient-rich gaster).
Brood young: army ants, possibly bullet ants.

Feature Facts

• Atta leafcutter ant colonies comparable in social complexity with honeybees and African fungus-growing termites; referred to as “superorganisms”
• Sophisticated division of labor and reproductive caste systems; single breeding queen can have more than 5 million workers that forage and cooperatively care for developing brood
• Queen, workers, and brood live in a vast subterranean nest complex with hundreds of interconnected fungus garden chambers
• Workers harvest and process enormous amounts of fresh plant matter to cultivate a specialized fungus as their almost exclusive food source
• Foragers travel along well-maintained trails; routes between nest and harvest sites marked with potent pheromones
• Small workers sometimes ride on leaf fragments being transported back to nest by larger workers to help deter parasitic flies that lay eggs in the necks of larger foragers
• Extensive leaf processing occurs below ground, sometimes taking 12 hours to cut, clean, mulch, and add the material to fungus garden in a pre-digested state
• Use chemical secretions, antimicrobial compounds, bacterial biofilms, gardening behaviors, and strict waste disposal practices to maintain their garden system (unique to each colony)
• When starting new colonies, young queens carry a small tuft of fungus during mating flight; queen lives off her body reserves and does not feed on fungus until first workers raised
• Atta cephalotes: a dominant and ecologically important species in tropical America, especially in rainforests and forest-edge ecosystems
• Considerable impact on plant communities and forest structure; an “ecosystem engineer”
• Atta considered a severe pest in agricultural and urban areas