Termite-hunting ants rescue injured comrades

In the endless war between ants and termites the injured are never left behind – at least on the ant side of the battle lines.

Research published today in Science Advances reveals that specialist termite predator the African Matabele ant (Megaponera analis) operates a medevac service for its soldiers during raids on termites.

The finding, by a team led by Erik Frank from the University of Würzburg’s Biocentre, is highly unusual. Ants – along with termites and some types of bees and wasps – are eusocial species, which demonstrate a level of colony organisation and collective action that render individual lives unimportant.

Entomologists – for instance, Bert Hölldobler and Edward Wilson in their book, Journey to the Ants (1994) – have documented many collective behaviours among ant species, including using massed bodies to make rafts, ladders, and shelters, all of which result in significant fatality rates.

Matabele ants, however, are different. Two to four times a day they descend on termite feeding grounds, killing their prey and dragging them back to the nest. Their opponents, however, are not exactly defenceless, and many of the ants are slaughtered or maimed by soldier termites, equipped with massive pincers.

Frank and his team observed that a wounded ant releases a specific chemical compound that serves to trigger a rescue response in other ants nearby. These then pick up the damaged insect and carry it back to home territory, where any attacking termites still attached are forcibly removed.

Those ants not too badly wounded eventually recover and return to active duty. The number that do so must be great enough for the unprecedented strategy to pay a survival dividend for the colony.

“We have observed helping behaviour vis-à-vis injured animals for the first time in invertebrates,” say Frank.