Ants Use Antiobiotics to Kill Weeds

Researchers at the University of East Anglia have found that ants which cultivate fungus farms use antibiotics to manage them. These antibiotics are employed to kill weeds which compete for space with the ant-cultivated fungus. The antibiotics are produced by a bacteria called actinomycete. This bacteria lives on the ants, which creates a symbiosis, or mutually beneficial relationship.

Acromyrmex octospinosus leaf cutter ants were investigated by Dr. Matt Hutchings and his students. These ants form some of the most complex and largest animal societies known. Some of their colonies number in the millions. Most of the work was conducted by the student workers. Dr. Hutchings mused, “This was really a fun project which started with a PhD student, Joerg Barke, streaking leaf-cutting ants onto agar plates to isolate antibiotic producing bacteria. Joerg, with his colleagues Ryan Seipke and Sabine Gruschow, really pushed this project forward and made these major discoveries. They really deserve most of the credit for this work.” (Source: Softpedia.com)

Acromyrmex leaf cutter ants eat a type of fungus as their main form of sustenance. Another symbiosis exists in the relationship between the leaf cutter ants and their fungus food, “The ant is supplied with a highly nutritious, readily acceptable food source in return for complex fungus-culture behaviour, providing protection from fungivores and competition from other saprophytic fungi.” (Source: Wiley Library)

To summarize the whole process, the leaf cutter ants have a mutually beneficial relationship with a bacteria that creates antibiotics the ants use to take care of a fungus, which keeps the fungus alive and provides ants with food to sustain themselves as well. The ants are so determined to protect the fungus and kill off competitors, because it provides the only food used by the queen which lays all the eggs for the colony, and for the larvae. If none of the fungus is available, the colony will not survive. They are careful fungus gardeners setting up a new fungus garden on a platform of rootlets separate from the main colony. They also practice hygiene cleaning their legs to ensure they are not tracking contaminants into the garden which could harm the fungus.

The research study also identified an antifungal which could be used to treat fungal infections in humans. It is similar to Nystatin, an antifungal cream which has been used for some time.

The type of bacteria used by the ants is Actinobacteria which play an important role in soil, and water (both fresh and saltwater) as a decomposer of organic material, meaning they turn decomposing life forms back into chemicals which are used again by other life forms.

Note: the video below which explains leaf cutter ant behavior is not from the same researchers referenced above.