Which Ants Have Formic Acid in Their Venom?

Several species of ants have formic acid in their venom. The formic acid serves a defensive role. Some ants use it as a biocide to kill off rival venom. They are able to do so because of a special gland in their abdomen.

The formic acid is a monoprotic acid composed of the planar molecules H-C(O-O-H) or HCOOH. The acid is a strong deterrent to predators. However, it can be very painful when in high concentrations.

In a new study published in the journal eLife, researchers show that some crazy ants have a new and unique mechanism for controlling the entry of pathogens into the ant’s body. Formicine ants actively swallow antimicrobial and highly acidic poison gland secretions. This may be a defense mechanism that allows these ants to keep opportunistic microbes from spreading to the nest.

It also may be a means of controlling bird parasites. Some birds aggressively preen over ant nests to exhaust the defences of the ants.

Formic acid also seems to have a significant impact on the ant’s intestinal flora. Researchers believe that this behavior is a result of an ancient evolutionary arms race.

The formic acid in the ant venom is too small to be fatal to humans. However, it is powerful enough to prevent imported fire ant venom from penetrating the ant’s exoskeleton.

Some ants use formic acid to repel and kill varroa mites, which attack honeybees. This is a process known as chemical mimicry.