Some ants disinfect food by drinking the acid they spray at enemies

A number of species of ants produce acid in a venom gland in their abdomen to spray their enemies. It turns out that they also drink this acid to kill pathogens in their food. Since these ants often vomit food to feed their fellow ants, this helps prevent the spread of disease in colonies.

Ants drinking acid to clean their food
Unlike the stomachs of vertebrates, those of insects are not normally very acidic. Simon Tragust, from the University of Bayreuth in Germany, and his colleagues have discovered that species such as the Florida carpenter ant (Camponotus floridanus) increase the acidity of their stomachs by swallowing acid after eating. If these ants were prevented from bending over to reach their venom glands, acidity levels were lower.

The team then fed the ants food contaminated with bacteria that can cause fatal infections. Ants that couldn't drink their acid were less likely to survive.

Finally, the team looked at the likelihood of disease transmission when ants fed other ants by regurgitation, as is often the case in these species. The venom glands of the ants were blocked with superglue. If the glands of the feeding ants were also blocked, more ants would die.

This acid plays a key role
These results show that acid consumption plays a major role in protecting these ants from microbes and in preventing the spread of infections in colonies.

"There is a clear advantage to this," says Liselotte Sundström of the University of Helsinki, Finland, who reported in 2015 that ants are self-medicating to fight fungal infections. However, it is not known whether ants actively drink this acid from their gland, she says, or whether it happens accidentally when they groom themselves.

Crazy tiger ants do the same thing.
Tragust's discovery is not the only example of ants using acid as a medicine. When wild fire ants are sprayed with the venom of fire ants, they apply acid to their bodies to detoxify the venom.