Leafcutter ants belonging to the genera Atta and Acromyrmex are well-known for their specialized gardening skills. Endemic to South and Central America, leafcutter ants cultivate specialized fungi on mulch that they make from chewed leaves. Unfortunately, the leafcutter ant’s fungal gardens are susceptible to a specialized fungal parasite known as Escovopsis that has co-evolved to feed on the ant’s fungal crop. If the parasite overwhelms the gardens, the ant’s food supply can be decimated and the entire colony can collapse. However, the ants are excellent and diligent farmers. They meticulously patrol their gardens and remove any foreign fungi and contaminants. They even maintain biofilms of anti-biotic producing bacteria on their bodies that they use to kill off parasites.
Researchers from the University of East Anglia (UK) have identified two families of molecules that are produced by the Escovopsis fungi that are used to overcome the ant’s defense systems. One of the molecules was able to kill the anti-biotic producing bacteria that grew on the ant’s bodies. The second molecule worked to modify the ant’s behavior, much as the renowned ‘zombie-ant’ fungus. When the leafcutter ants were exposed to this ‘mind-control’ molecule, they would stop grooming their gardens and leave the nest and eventually die if sufficiently exposed.
There is also evidence that the ants may be fighting back by obtaining new strains of anti-biotic bacteria from the soil that can be more effective against Escovopsis. These findings are consistent with a biological arms race where each organism is trying to gain the upper hand. It also highlights the role that natural products can play in pathogen control and may help address issues of anti-biotic resistance in human medicine by providing novel sources of anti-biotics.
University of East Anglia. (2018, June 7). Deadly behavior-modifying weapon identified in insect-world chemical arms race. ScienceDaily. Retrieved September 30, 2018 from www.sciencedaily.com/releases/2018/06/180607082553.htm
Heine, D. et al. (2018). Chemical warfare between leafcutter and symbionts and co-evolved pathogen. Nature Communications, 9: 2208. DOI: 10.1038/s41467-018-04520-1
Author: Doug Minier09.30.18