Mutualism and Leaf Cutter Ants: How It All Works

leaf cutter ants

Leaf ants are one of the most interesting ant species in the entire world. Found across Central America, South America, and parts of North America, leaf ants, which are also called leaf cutter ants, have several characteristics that make them unique when compared to other ant species. One peculiarity that sets them apart is their participation in mutualism.

In fact, mutualism is a defining characteristic of leaf cutter ants. As such, leaf cutter ant mutualism deserves more study and attention. Learning about leaf cutter ants mutualism can help you can understand more about how these small creatures live and what makes them so interesting and unique. 

What is Mutualism?

Before discussing leaf cutter ants mutualism, let’s understand what mutualism is and how it works in general. While mutualism might seem complicated, it’s actually very simple if you know the right facts. Mutualism is also commonly referred to as a symbiotic relationship, which are relationships between multiple species. While most people assume that symbiotic relationships are beneficial all around, but this isn’t always the case. In reality, there are several different types of symbiotic relationships that affect each species in different ways.

For example, parasitism is a symbiotic relationship where one species benefits at the expense of another. Another type of symbiotic relationship called commensalism, which is when one species is not affected by the relationship while the other species benefits. Mutualism, as you may suspect, is a symbiotic relationship where every species involved benefits in some way. If you want the perfect example of mutualism, look no further than the leaf cutter ant. 

Leaf Ants and Mutualism


Image via Flickr by dullhunk

Leaf ants get their name from their habit of leaving their colony to forage for leaves. After cutting leaves, the ants will bring them back to their colony. However, these leaves aren’t for consumption. Instead, they are used to grow fungus within the leaf cutter ant colony, which is where mutualism comes into play.

When leaf ants bring foliage back to their colony, they will grind up the leaves. Once this process is complete, they will place the plant material in a fungus garden so that the fungus can grow. The ants will then eat the fungus. So, the ants and the fungus that they grow are involved in mutualism. The fungus is provided with the plant material it needs to grow and the ants have a consistent food source.

Another example of mutualism when it comes to leaf cutter ants has to do with how the ants maintain their fungus garden. Fungus can only grow if it is free from pests, which means the leaf ants must constantly tend their garden to prevent these fungi pests from spreading. On the skin of leaf ants live bacteria whose only purpose is preventing fungi pests. Leaf ants and the bacteria on their skin are also involved in mutualism because the bacteria are allowed to live on the ants in exchange for helping the ants care for their fungus garden.

Now that you know the basics of leaf cutter ants mutualism, we can dive into this subject in greater detail. 

Starting the Colony

Perhaps the most interesting fact related to leaf ants is how their colonies and their fungus gardens are formed. During mating season, a young leaf ant queen will set out to start a new colony. In order to do so, she takes a small amount of fungus from her old colony. After a bit of searching, she will find a spot that’s suitable for laying eggs and starting a new colony.

The queen will lay her eggs and build a chamber for the fungus. Once the eggs hatch, the new worker ants will be responsible for tending to the fungus to support mutualism. Until that time occurs, the queen will take care of the fungus. Leaf cutter ants are considered social insects, which means different ants serve different roles within the colony. Some ants will forage for leaves, others will take care of the fungus garden, and some will be responsible for defending the colony. 

Preventing Contamination

Because leaf ants and the fungus that they tend to and eat are so dependent on each other, both are especially vulnerable to harm. For instance, both can be killed by a variety of microbes, many of which can be found on the leaves that the ants and the fungus need to survive. Fortunately, their symbiotic relationship works to protect each species from harm.

First, fungus has the natural ability to protect itself from microbes by producing antibiotics, which can also protect ants when they eat the fungus. Second, when ants grow their garden, they are very careful about cleaning both themselves and the fungus. In addition to weeding their gardens, many leaf ant colonies have a dedicated waste storage chamber, which serves to further protect the garden. The fecal matter of leaf ants also contains several chemicals that can suppress pests and promote fungal growth. As you can see, the relationship between ants and fungus gardens helps to protect both, which is the essence of mutualism. 

Antimicrobials and Ants

In a previous section, we briefly touched on the fact that certain types of bacteria can live on the skin of leaf ants. Examining this issue in a little more detail can help you better understand how mutualism works.

These bacteria are very interesting in that their antifungal properties will attack pests while leaving the fungus in the garden unharmed. This bacteria, which is usually Actinobacteria, reside on the ant’s belly, meaning it will easily be transferred to the fungus. In some cases, the fungus will develop a resistance to the beneficial bacteria, meaning it will no longer be protected from pests. When this occurs, it’s possible that the colony will collapse. Leaf cutter ant mutualism is one of the main reasons that the leaf cutter ant is a particularly fascinating ant species. You can learn several other fascinating facts about leaf cutter ants by consulting with an ant professional


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