Ant-fungal interactions, both friend and foe

Abstract

A wide variety of aspects in human life are affected by fungi. Fungi themselves are commercially grown for the consumption of mushrooms, and produce various proteins, antibiotics and other small molecules in the industry. They are also organisms that play a major role in the biodegradation of dead plant material and ensure the recycling of nutrients. In addition, fungi frequently form mutualistic, parasitic and commensal interactions with insects, including the ant, these interactions are important but not yet fully understood. The Ophiocordyceps is a parasitic fungi that infects a broad range of insects, however this interaction is best known for infection in ants. By infecting the ant, the fungi incorporates itself within the host. With chemical infiltrations to the brain the fungi alters the expression of certain genes, which has an effect on the levels of adenosine and ergothioneine present in the host. Such adaptations lead to behavioral changes different from their natural ones. For instance the ant is forced to leave its nest beneath the ground and climbs into the forest canopy, when positioned underneath a leave the ant performs a death grip and dies. From this point the fungi takes over its host completely, by consuming the ant an inside out consumption. The fungi acquires the needed energy to produce its fruiting body that grows out of the ant, what results in the production of spores which can infect new hosts within the environment. This infectious lifestyle can be dated back to 23-66 million years ago, to maintain these interactions over a longer period of time evolution of new defense and attack strategies are needed. The Lepiotaceae fungi forms a mutualistic interaction with an ant, in particular leaf-cutter ants. The ants harvest fresh plant material to feed the fungi and in return it forms primordia, fungal structures of which ants can feed. This interaction has become obligatory and special chambers are developed within the ant’s nest. To protect the fungal garden a few extra measurements have evolved over time. The social immunity of an ants nest will include the fungal gardens. Extra mutualistic interactions between the ant and other antifungal producing microorganisms, actinobacteria, that don’t effect the Lepiotaceae cultivar have been acquired. Semiochemicals ensure communication between fungi and ant, to minimize damage from plant materials that inhabits pathogens or includes toxins that are harmful to the fungal colony. The leaf cutter ant can be seen as a pest when large parts of crops disappear from herbivory. To protect crops against attacks like these and other instances a parasitic pathogen like the Ophiocordyceps fungus can be used as a biocontrol agent. This method is more environment friendly than with the use of chemical compounds, the instances of resistance against biocontrol agents has a higher change of remaining low and it has a more specific pathogen target. The Ophiocordyceps might even be used in future medicine due to the improvement of human health.