Matabele ants (Megaponera analis) are the Florence Nightingale’s of the insect world, taking special pains to save comrades injured while fighting.
Individual ants dress the wounds of soldiers damaged in battle and, as far as biologists know, they are the only insect to do so. Now, research published in Proceedings of the Royal Society B reveals just how effective this unique behavior is.
Injured ants who received this treatment were able to survive for at least 24 hours 90 percent of the time. In comparison, only 20 percent of injured ants made it 24 hours without treatment.
Matabele ants live a hard life. Two to four times a day, they leave their colonies to raid termite hills, trekking up to 50 meters (160 feet) across the Sub-Saharan terrain in columns 200 to 600 animals long.
When they reach their final destination, the ants split into two groups. The majors destroy the soil barrier protecting the termites and the minors burst in to kill and remove their prey.
As you might imagine, this line of work comes with a high risk of injury. Soldiers frequently lose limbs that have been bitten off by termites – and this is where the species' unique nursing behavior comes into play.
Last year, a team of biologists from Julius-Maximilians-Universität Würzburg (JMU), Germany discovered that ants who sustain injuries emit a chemical substance to call for the help in the way we might use a flaregun.
If only one or two limbs are damaged, the ant will move around slowly when close to potential helpers and pull in their remaining legs to aid the journey home. Badly injured ants – say, those with five missing or damaged limbs – will instead move around frantically, lashing out at helpers.
"They simply don't cooperate with the helpers and are left behind as a result," Erik Frank, who co-authored the paper, explained in a statement.
Now, the team has observed what happens when the ants return to the nest. Six Matabele ant colonies were brought into lab conditions, where a few unlucky individuals were purposefully wounded. Researchers pulled off two limbs and watched as healthy ants carried their injured mates back to the artificial nest.
This is when the grooming began. Healthy ants "licked" the open wounds of injured ants for periods of up to four minutes, which researchers believe helped clear the area of dirt and protect against infection.
"We suppose that they do this to clean the wounds and maybe even apply antimicrobial substances with their saliva to reduce the risk of bacterial or fungal infection," Frank added.
This Florence Nightingale-like behavior is thought to have developed to benefit the health of the colony in a species at high risk of injury.
"To minimize these costs, adaptations occurred both on the social level (rescue and treatment) and the individual level (wound sealing/clotting)," the study authors conclude.
A Matabele ant nurses a mate back to health. Erik T. Frank