Fungus-growing ants

The fungus growing ants are found throughout Central and South America and the southern states of the USA. They have a mutualistic relationship with a fungus. The ants gain food from the fungus and the fungus gains a place to live protected by the ants from predators and parasites.

There are many different species of fungus-growing ants, but they all belong to the tribe Attini. The higher attines include the well-known leaf-cutter ants, while the lower attines are a less well studied group which tend to have small colonies and collect a variety of foods for their fungus. Several different species of fungus-growing ants are studied at the Universities of Copenhagen and Aarhus, representing both the lower and higher attines.

A colony of Atta, probably the best known of the leaf-cutter ants is shown below. Many of the same features are shown to a greater or lesser degree by the other fungus-growing ants. Click on the pictures or the text below to find out more.

A nest of an Atta leaf-cutter ant:

  1. Sections of leaves are cut from vegetation around the nest by specialised workers.
  2. The leaf sections are carried away along trails.
  3. The leaf sections are taken back into the ant nest, where they are given to another group of specialised workers that process the leaves.
  4. The processing workers reduce the leaf fragments to a mulch which is used to feed the ant colony's fungus garden. The fungus feeds on the mulch and uses the nutrients to grow. It also produces special structures called gongylidia which are fed on by the ants.
  5. The queen sits among the fungus garden laying her eggs. When the eggs hatch, the larvae that emerge will eat the gongylidia while they are being cared for by specialised nurse workers.
  6. When the nutrients have been removed from the leaf material, the waste is transported to special dump chambers, where dead ants and dead fungus are also placed.

Research on fungus-growing ants at Copenhagen and Aarhus

At the Universities of Copenhagen and Aarhus we are studying several related aspects of the relationship between fungus-growing ants, their fungus and their parasites:

Mating frequency

The fungus-growing ants have a variety of social structures. Many species have only a single queen, but our research has found that certain leaf-cutter ant queens mate with many males, having the highest mating frequency of any ant. Why do they do this? Click here to find out more.

Parasites, diseases and antibiotics

The fungus-growing ants are particularly vulnerable to parasites because they are dependent on the survival and health of their mutualistic fungus as well as their own health. The ants therefore seem to have particularly well developed mechanisms for coping with parasites, including the production of antibiotics. Click here to find out more.

Social parasites

Like many other social insects, the fungus-growing ants are also vulnerable to attack by social parasites - other species of ant that use the workforce of the fungus-growing ant colony to raise their own offspring. Click here to find out more.

 

Collaborations, and the EU-TMR network on Social Evolution

Much of the research at the Universities of Copenhagen and Aarhus on fungus-growing ants is done in collaboration with other research groups, particularly the other members of the EU-TMR network on social evolution. Click here to learn more about these collaborations.