Fungal-Fungal Interactions in Leaf-Cutting Ant Agriculture
The obligate mutualism between fungus-growing ants and microbial Panamanian Acromyrmex echinatior leaf-cutting ants primarily .. fungus gardens, where infection problems with Escovopsis are most likely to occur . Keywords: Hypocreales, Attine ants, Escovopsis, Symbiosis. Go to: Leafcutter ants cultivate two phylogenetic clades of fungi including Leucoagaricus Managing leaf-cutting ants: peculiarities, trends and challenges. The fungus, ant, bacteria relationship is so special because of the intertwined This is how they keep their nest so clean and disease free. But the harvesting ants cut the leaves without ingesting any of the toxins and are.
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. 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. This speeds up decomposition in one place that would be spread out around the forest.
Decomposition could also be hindered by the toxic qualities of the leaves leaving them inedible to other macro or micro invertebrates. Decomposition is also aided by the previously mentioned nitrogen fixation process. Bringing nitrogen into the system helps to decrease the carbon to nitrogen ratio which speeds up the decomposition processes. Niche This is a split side view of an underground chamber where the fungus and the queen is housed.
Every new colony starts with a small room like this one,which starts with a queen moving to a new place carrying the fungus in her mouth. Nest Characteristics Nests begin when a queen ant leaves one nest with a small amount of the fungus in her mouth and moves to a different area to start her own colony.
Once a nest becomes established, the colonies can grow to have millions of ants in them. These subterranean nests vary in sizes. They can be small with a single fungus growing "room" or can be multiple feet below ground with many different rooms and complex tunnels. Ants are also known as organized and clean insects. They have certain refuse dumps where the worker ants take the garbage and seclude it from the rest of the colony to decrease contamination.
Major Players There are a total of five major players that interact with the leafcutter ants. There are the attine ants, their cultivated Lepiotaceae fungi, the parasitic fungal escovopsis parasites that feed on the cultivated fungi, and the latest partner; the black yeast found on the ants to help rid the colony of antagonistic invaders.
Ants The group of ants that are LeafCutters belong to the tribe attini and their genera is Atta and acromyrmex These ants have been around for the better part of 50 million years. Interestingly, these ants are consume the largest amount of primary producers in the tropical rainforest areas which is not surprising considering their biomass is four times the amount of other invertebrates.
World wide, these insects take up a third of the total insect biomass. Fungi Playing the role of both a decomposer and the primary food source for the Leafcutters, the fungi from the family Lepiotaceae is grown underground in the nests chambers by the worker ants. Other types of fungi can creep into the system, but are taken care of by the ants and are not allowed to keep surviving in the system.
Bacteria Actinomycete bacteria are found in the underbellies of the worker ants. If the ants are in often close contact with the fungus, they tend to have more bacteria on them. This is because the bacteria has a special property that acts as antibiotic against other molds and fungi, except the ants' food source, the Lepiotaceae fungus. Parasites Battling against the ant's seemingly clean fungis' agriculture are parasites that would quickly take over the colony's fungus growth if not carefully weeded against.
These can be competing molds or funguses that would come along and compete with the fungi for the delicious broken down vegetation. The ant's fungi cant survive against the invaders.
How Ants Became the World’s Best Fungus Farmers | Science | Smithsonian
Some of these parasites are refered to as escovopsis, and would feed on the fungus Reynolds, Black Yeasts There has recently been research conducted on a fourth fungal partner. One of the most interesting and only recently discovered partners is the antibiotic producing fungi Ascomycota; Phialophora.
This is a black yeast that can be found on the cuticle of the ant and is used in a similar fashion in discouraging parasitic growth. This yeast has evolved with the ant-fungi symbiotic relationship and according to Little et al, the research into this partner shows how complicated and sophisticated this symbiotic partnership can be Little, The fungus is prevalent in different geographical areas with the attine ants, and therefore the researchers concluded that the fungus is indeed a fourth symbiotic partner within the fungus, ant, bacterial mutualistic relationship Little, Current Research Coevolution between attine ants and actinomycete bacteria It has been the thought that the close relationship between the ant and the bacteria has caused the two to evolve together.
Escovopsioides as a fungal antagonist of the fungus cultivated by leafcutter ants
But the study looks at if that is truly so. It concluded that the ant has probably evolved with the bacteria, but the bacteria has evolved independently. The study states that more research needs to be done on the reciprocality of the evolving partners Dash, Enzyme activity activity in different ant colonies Ants have evolved into different sister clades.
This research shows how the enzyme activity between lower and higher evolved colonies has changed.
The study shows that higher evolved colonies contain more protein and starch digesting enzymes while those of lower clades have enzymes that just focus on partial degradation of the plant material De Fine Licht, Ant Genome The complete ant genome has recently been mapped out. With that, their are multiple studies going on about the evolution of the ants with its symbiotic partners and other attributes of the ant.
Especial focus is put on the antimicrobial properties of the bacteria Ulrich, Evolution and Competition There are studies conducted to how the ant and its partners have evolved together and how they originally came to work together.
Worker ants go out to forage for fresh leaf material that they use to grow a fungus Leucoagaricus gonglyophorous. In return for a mulchy compost of fresh leaves, the fungus breaks down the plant material to produce nutritious, edible structures which the ants can digest.
- Ant–fungus mutualism
- How Ants Became the World’s Best Fungus Farmers
- Leafcutter ants, fungi, and bacteria
As all farmers are well aware, crops are prone to outbreaks of disease. South American leafcutter ants face a similar problem in that their fungal gardens can become infested with parasites, usually other bacterial and fungal species that feed off the nutritious fungal crop.
Escovopsis, in particular, is specialised to grow on the leafcutter ant garden and can be devastating to an ant colony.
This causes many ants to die and the remaining individuals to eventually abandon their normally well-tended gardens altogether. Several decades of research have shown that, over millions of years, the ants have evolved several lines of defence against Escovopsis infections.
The ants weed out pieces of infected fungus and can also produce several antimicrobial chemicals that they spread over the garden.
Leaf Cutter Ants
Shutterstock As well as producing their own forms of pesticide, the ants also commission the help of antibiotic-producing bacteria called Pseudonocardia, which they grow on their bodies and whose chemicals can inhibit the growth of Escovopsis. But we now understand that this assortment of weaponry is only one side of an arms race. Escovopsis has developed its own suite of chemical missiles that block ant defensive behaviours and kill the helpful antibiotic-producing bacteria.OMG! Leafcutter Ants WILL BLOW YOUR MIND - Thanksgiving Special - Part 1
This explains how infections can escalate and eventually lead to colony collapse. Chemical techniques called liquid chromatography and mass spectrometry were applied to identify and measure the amounts of particular molecules that the Escovopsis was producing. We were able to isolate two families of chemical, called melinacidin IV and shearinine D, whose production increased once the food fungus was infected.