This sort of stuff really astounds me. The leafcutter ant creates fungal gardens that are used to feed larvae. They protect the health of their gardens by using various bacteria as antibiotics:
The antibiotics act both as herbicides and regulators of fungus growth. The antibiotics are produced by actinomycete bacteria, which live in a state of symbiosis with the ants, and are found on the bodies of the ants themselves. The symbiotic relationships benefit both the ants and the bacteria.
And there are some implications for human medicine.