How Ants Became the World’s Best Fungus Farmers | Science | Smithsonian
Ingenious leafcutter ants have developed a successful symbiotic relationship with the fungi they farm. New genetic analysis helps pinpoint. The leafcutter ants, or attine ants, include the genus Atta and they eat a The ants and their fungi form a true symbiosis, with both partners benefiting from the. Leaf-cutting ants maintain an obligate symbiosis with their fungal cultivar . This information will help us understand the sources of the puzzling.
This relationship has previously been refered to as the "First Agriculture. The fungal colonies once seemed to be free of any pests or parasites. This was thought to be because the ants were cared fro the fungas in such a diligent way taht they did not allow any parasites to enter and take hold. This theory was widely accepted until Cameron Currie took a closer look at what process was specifically keeping the nests parasite free.
Leafcutter ants, fungi, and bacteria - microbewiki
He noticed that when the ants were removed from the nest,the fungi was quickly taken over and destroyed. He was the first to find that the ants carried a white powdery bacteria on their abdomens that had antimicrobial properties. Without the ants, the parasitic mold could take over the fungus in the colony in a matter of days Little, Symbiotic Processes A worker ant harvesting the fungus who is covered with the powdery white bacteria that helps the fungus stay parasite free.
The fungus, ant, bacteria relationship is so special because of the intertwined actions and benefits that they each have. The fungus and the ants depend on each other for survival and one can not live without the other.
The ants cultivate the fungus in its colonies from chewed up leaves and at the same time the fungus acts as the main food source for the ants.
Biological Interactions The interaction begins when a queen attine ant leaves her original nest with a chunk of the Lepiotaceae fungus in her mouth, and colonizes a new nest. From there she can lay and the original piece of fungus can begin to be cultivated. To cultivate the fungus, the foraging ants go out and cut chunks out of leaves without ingesting any of the leave's toxic chemicals and bring them to the worker ants in the colony. Those ants take the leaves, chew them up, and use the pulp as a substrate for the fungus to grow on.
This fungus is their main food source. The fungus could not survive without the ants, and the ants cant survive without the fungus. But the ants have a special weapon in their arsenal for cultivating the fungi.
Leafcutter ants, fungi, and bacteria
They use the antibiotic producing actinomycete bacteria, that grows on the ants, as an antibiotic against outside sources of fungi and molds.
This is how they keep their nest so clean and disease free. The antibiotic agent discourages the growth of fungi, except the specific fungi that the ants are growing. This is one reason why this interaction is so interesting, the different partners work specifically with each other in order to form a balanced and well functioning system that has lasted a very long time.
Fungi Growth The leaves in the rain forest have toxic qualities in them which is supposed to deter herbivory. But the harvesting ants cut the leaves without ingesting any of the toxins and are able to bring the leaves back to the nest.
There the leaves are given to worker ants which chew up the leaves in their mouths into a paste which becomes the food source for the fungus.
The plant material is broken down through enzymes that break down the proteins and starches. Depending on the colony, the enzymes used can be slightly different promoting a complete plant break down or only a plant wall digestion. Because of the symbiotic relationship, the toxins in the leaves are able to be broken down by through enzymes from the fungi into needed sugars and proteins safe for the ant to consume.
Bacterial resistance to fungal parasites To maintain a clean and healthy fungus colony, the ants have a bacteria on their exoskeleton which they use when cultivating the fungus.
Some ants have this on their underbelly while ants that are in constant contact with the fungus are almost completely covered with the bacteria. This is an example of the complete evolutionary relationship bewteen the ant, the fungi, and the bacteria. The ants are able to use the bacteria, Pseudonocardia, with antibiotic qualities to fight against any invasive molds or fungi.
This bacteria is similar to the bacterium which produces half the antibiotics made today. The antibiotic qualities allow it to specifically work with the fungus to inhibit the parasitic mold. Unlike the ant, fungi, and bacteria symbiosis, present day antibiotics often produce resistant types of pathogens.
It is thought that the ant colonies do not produce antibiotic resistant molds because of the high diversity of the bacteria and as the two evolve together the parasitic mold will not evolve a resistance. Another method to cultivate only its native strain of Pseudonocardia is that the ant's feces contain incompatibility chemicals which select only for its resident fungus.
There are also behavior cues which suggest that the ants physically pick out other types of fungus. Environmental Implications The millions of ants in the forests have a huge effect on the ecosystem. For such a small organism, it has a huge effect. Nitrogen Fixation Like any other garden, the ant's fungus garden needs nitrogen in an available form fit to be used by the microorganisms. Research has showed that the fungus garden in the ants' nest fixes nitrogen. This means that the fungus is taking atmospheric nitrogen and reducing the nitrogen to produce ammonium.
Even after the nest uses the nitrogen that it needs, there is still a large amount of available nitrogen that can be entered into the surrounding system.Evolution coevolution of the ant and fungi
This replenishes the nutrient poor tropical environment with an essential limiting nutrient Pinto-Tomas, Decomposition The ants cut and collect a huge amount of forest vegetation each year. Needless to say, this has a huge effect on the tropical forest system. The decomposition effect of the ant-fungal-bacterial relationship needs to be considered when assessing the environmental impact of the relationship.
When the plant material is brought to the nest, decomposition is aided by the ants chewing and initially breaking down the material, which can then be used as a substrate for the fungi. They may have been eating fungi for up to 50 million years, and during that time they have co-evolved with their fungal partners.
The photo below shows the nests of leafcutter ants: The ants and their fungi form a true symbiosis, with both partners benefiting from the relationship. The ants benefit by exploiting leaves: The fungi break down the indigestible cellulose of plants, converting it into more edible proteins and sugars which the ants can harvest.
The ants, in turn, provide all the food the fungus needs, carefully selecting the leaves that the fungus prefers, and even secreting antibiotics to prevent bacteria from growing on the rotting leaves in competition with the fungus. The ants also carry the fungus around when they move to a new location. The queen ant takes a small amount of fungus in her mouth, and after she mates she digs a hole and spits out the fungus to start a new nest. The image to the right shows a large queen ant surrounded by smaller worker ants.
Fungi are classified as Ascomycetes, Basidiomycetes or Zygomycetes based on the spores that they produce.