Request PDF on ResearchGate | The Mutualism between Leaf-Cutting Ants and their Fungus | The appendix, co-authored with Peter. Microorganisms often require a symbiotic relationship with other between leafcutter ants, fungi that are specific to the leafcutter nests, and a . areas including Costa Rica, Panama, and Argentina (Pinto-Tomas, ). Some tropical ants collect leaves which they use to grow fungi in their undergound nests. The leafcutter ants, or attine ants, include the genus Atta and they eat a form a true symbiosis, with both partners benefiting from the relationship.
Acromyrmex and Atta exhibit a high degree of biological polymorphismfour castes being present in established colonies—minims, minors, mediae, and majors. Majors are also known as soldiers or dinergates. Atta ants are more polymorphic than Acromyrmex, meaning comparatively less difference occurs in size from the smallest to largest types of Acromymex.
Leafcutter ant - Wikipedia
Leafcutter ant Atta cephalotes Minims are the smallest workers, and tend to the growing brood or care for the fungus gardens. Minors are slightly larger than minima workers, and are present in large numbers in and around foraging columns. These ants are the first line of defense and continuously patrol the surrounding terrain and vigorously attack any enemies that threaten the foraging lines. Head width is around 1.
Mediae are the generalized foragers, which cut leaves and bring the leaf fragments back to the nest.
Majors, the largest worker ants, act as soldiers, defending the nest from intruders, although recent evidence indicates majors participate in other activities, such as clearing the main foraging trails of large debris and carrying bulky items back to the nest.
Ant-fungus mutualism[ edit ] Their societies are based on an ant-fungus mutualismand different species of ants use different species of fungus, but all of the fungi the ants use are members of the family Lepiotaceae. The ants actively cultivate their fungus, feeding it with freshly cut plant material and keeping it free from pests and molds. This mutualistic relationship is further augmented by another symbiotic partner, a bacterium that grows on the ants and secretes chemicals; essentially, the ants use portable antimicrobials.
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.
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. 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.Planet Ant - Life Inside The Colony - BBC
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. 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.
Fungal-Fungal Interactions in Leaf-Cutting Ant Agriculture
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.
- Leaf Cutter Ants
- Leafcutter ant
- Leafcutter ants, fungi, and bacteria
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.