Last time we found out that the fungus of Leafcutter ants can be pretty weak against diseases. This can cause big problems for the ants, because they are completely dependent on the fungus for their food.
Unfortunately for them, a parasitic fungus called Escovopsis is all too willing to disrupt the peaceful collaboration between ants and their garden. This parasite is specialized in killing and eating the ant’s fungus. Bad news for the ants! However, by invoking the help of another organism, the ants are not completely defenseless against these attacks.
If you look closely at the ‘chest’ (thorax) of many Leafcutter ant worker, it appears very white and dusty. This ‘dust’ are actual bacteria, living and growing in special pockets the ants have in their chest. These bacteria produce antibiotics in exchange for having a safe place to live. By transfering these antibiotics from their symbiotic bacteria to their infected fungus, they can kill the Escovopsis, and by doing so, save their colony from certain death. Thus, ants not only have agriculture like we do, but they also use pesticides to keep their crops out of harms’ way!
Currie et al. (1999), Fungus-growing ants use antibiotic-producing bacteria to control garden parasites. Nature 398, 701-704