Leaf Cutter Ants

There are ants all over the place here, and there are lots of type of ants too, but this page will focus on the fascinating Leaf Cutter.

You can tell they are around by the tell-tale path they wear into the ground with their constant travels.

3 inch path worn in our orchard

Leafcutter ants are social insects found in warmer regions of the Americas. These unique ants have evolved an advanced agricultural system based on ant-fungus mutualism. They feed on special structures called gongylidia produced by a specialized fungus that grows only in the underground chambers of the ants‘ nest.

Different species of leafcutter ants use different species of fungus, but all of the fungi the ants use are members of the Lepiotaceae family. The ants actively cultivate their fungus, feeding it with freshly-cut plant material and maintaining it free from pests and molds. This mutualist relationship is further augmented by another symbiotic partner, a bacterium that grows on the ants and secretes chemicals- essentially the ants use portable antimicrobials. Leaf cutter ants are sensitive enough to adapt to the fungi’s reaction to different plant material, apparently detecting chemical signals from the fungus. If a particular type of leaf is toxic to the fungus the colony will no longer collect it.

Waste management

Interestingly, leaf-cutter ants have very specific roles when it comes to taking care of the fungal garden, and dumping the refuse. Waste management is a key role for each colony’s longevity. Escovopsis is of course a constant danger to the ants. The waste-transporters and waste heap workers are the older more dispensable leaf-cutter ants, ensuring that the healthier younger leaf-cutter ants can work on the fungal garden. The Atta colombica species, unusually for the Attine tribe, have an external waste heap. Waste-transporters take the waste, which consists of used substrate and discarded fungus, to the waste heap. Once dropped off at the refuse dump, heap-workers organise the waste and constantly shuffle it around to aid decomposition. A compelling observation of Atta colombica was that the dead ants were placed around the perimeter of the waste heap.

Source: Wikipedia

Ants with their leaves

As you might expect, many leaf-cutting ants cut the leaves of trees. Here, workers of one type of leaf-cutting ant called Atta cephalotes cut the leaf of a grapefruit tree. Workers of different size do different jobs. While the larger workers cut the leaf, the smaller workers guard them against attack by flies. As in all ants, the workers are all female.

When the larger worker finishes cutting a leaf fragment, smaller workers climb onto the leaf fragment to guard the larger worker. Leaf-cutting ants can carry loads weighing up to twelve times their own weight. Usually, they carry loads only two to four times their own weight. Leaf-cutters often cut leaves fifty to one hundred meters away from their nest. Each round-trip to a tree may take an ant several hours. Back at the nest, the ants do not eat the leaf fragments. Instead, smaller workers cut the leaves into small pieces which they use as fertilizer for growing a fungus that they use for food.

Leaf-cutting ants are important enemies of trees in the forests and orchards. But, they are also helpful to

plants, and they fertilize the soil with all the vegetation they carry down into their nests

Leaf-cutting ants have no sting, but they have a powerful bite.
Source: http://www.thewildones.org/Animals/atta.html

AHA!!! I think I just figured out why the tress in our orchard don’t look as lush as the ones in the orchard on the way to our place – the ants! It said in the wikipedia page that to deter ants from defoliating the trees we should, “Collect the refuse from the nest and placing it over seedlings or around crops resulted in a deterrent effect over a period of 30 days.”

SO all we have to do is find thier refuse pile and sprinkle it around our trees. That shouldn’t take too long, I made a map of  the orchard yesterday and there are only about 60 trees!