Little Doctors: Ants and Antibiotics

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It is well known that ants are social creatures, with the ability to lift objects 100x heavier than their own weight. Less well known, however is the possibility that ants could be better equipped for diseases than humans!

Leaf-cutter ants live in the south American tropical forests. They are special because they have their own ‘fungi gardens’, which they grow so that they always have food for their colonies. These gardens are started by the colony’s queen ant, who transfers a small bite of fungi from her previous colonies garden to her new colonies garden. These gardens are maintained by the worker ants but are constantly growing and changing as neighbouring colonies, and wild-growing strains of fungus are constantly being introduced to their beloved garden; they do this to maintain diversity in their crops, which can prevent disease.

However, this diversity comes with a price – when collecting different strains of fungus for the garden, worker ants can pick up parasites on their bodies and bring them with them, which could destroy all of their crops if given the chance. Luckily, the ants can fight back; on the ants’ bodies, live antibiotic-producing bacteria, which control the parasites threatening their fungal gardens. Ants have been using these antibiotics for much longer than humans have (approx.. 49,999,920 years longer than us!).

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This relationship raises questions, however; humans have been using antibiotics for over 80 years, but are struggling in the battle of antibiotic resistance. However, ants have been using antibiotics for millions of years and don’t appear to be having the same issue… But how?

Scientists think this is because of a couple of things that the ants have been doing for all of those millions of years:

1. Co-evolution – This slow and complex process is likely the biggest reason. The ants have the ability to pass-on small bits of fungus and antibiotic-producing bacteria from colony to colony. Each new colony will have the antibiotics that their ancestors have been using, and in turn will add their own new antibiotics to the collection during their lifetime, which will later be passed on to their offspring. This cycle will continue for as long as the ants are alive and healthy. That process is an example of coevolution; the ants, fungus and bacteria improving their ability to fight disease over time, due to each-other’s efforts.
2. Environmental sampling – These ants have been actively trying to find new bacteria to make antibiotics for them! A study from Barke et al. in 2010 found that the ants continually search the soil around them for bacteria, and choose the species that they find most useful to keep on their bodies. This means that they have a huge range of antibiotics available to them, so they fight against lots of different types of parasite.

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These tropical ants look after their crops by covering their bodies in bacteria that can fight off parasites, so the leaves that they use to feed their fungi farms are cleaned before they are brought home – stopping their gardens from becoming infected with pesky pests. We can certainly learn a lot from these small creatures; they show us that working with other organisms can bring different benefits – in this case, aiding both medicine and agriculture. If we want to improve our own systems, we could learn from nature’s co-evolved relationships. But, if we want to take notes from these ancient relationships, we need to preserve the places that they are found; if we keep deforesting tropical forests, these ant colonies may cease to exist.

Where to find out more:

• Ants can lift 100x their own body weight: https://www.sciencefocus.com/nature/how-strong-are-ants/
• Ant fungal farms and their antibiotic-producing bacteria: https://www.nature.com/articles/19619
• Environmental sampling: https://bmcbiol.biomedcentral.com/articles/10.1186/1741-7007-8-109