Ants and Fungus

Fungi can be found nearly anywhere on earth, and species have developed complex interactions with many other organisms.  Ants are also nearly ubiquitous, and the intersection of myrmecology  and mycology is fascinating.

Atta cephalotes workers carry leaves to their nest

Leafcutter ants are easy to find in Costa Rica.  They keep their foraging trails clear of debris; the busy highways really stand out among the leaf litter of the jungle floor.  The zampopas as the locals call them do not eat the leaves they collect, but use them to farm fungus that is fed to developing ants.  The ants grow only one type of fungus, and are able to prevent other types of fungus from growing in their farms.  The leafcutters and fungus have evolved a 'mutualism' where both the ants and the fungus benefit from the interaction, however, this happy arrangement is not the case for all ant-fungus interactions:

Fruiting bodies of Cordyceps grow from the corpse of an ant that the fungus has killed.

Fungi in the genus Cordyceps are parasitoids (a parasite that eventually kills its host).  Most cordyceps  attack insects, and are very specific as to the species they can develop on.  As the fungus infects, it also alters its host's behavior to increase the chances of spores infecting another host, as seen in this BBC clip:

Host behavior modification by parasites is more common than you might want to imagine, but there is no need to worry in this case; there is no Cordyceps that specializes on humans.  I have been told however that there is a video game in development that features just that scenario in the storyline.