Termite-hunting ants injured in battle send a chemical S.O.S. signal

Unlike humans, when ants get injured, they can’t call for help. Instead, some ants employ a chemical SOS signal to get whisked off to safety. According to a new study, Megaponera analis, a species of termite-hunting ant found in sub-Saharan Africa, releases dimethyl disulfide and dimethyl trisulfide when injured in battle (Sci. Adv. 2017, DOI: 10.1126/sciadv.1602187). The pheromone cocktail attracts the help of larger M. analis ants, which rescue wounded soldiers by carrying the injured insects back to the nest for recuperation. By saving injured comrades, this species reduces combat mortality. Modeling studies predict that colony populations are nearly 30% larger because of the rescue strategy, explains Erik Thomas Frank, who led the study along with Thomas Schmitt, both of the University of Würzburg. The behavior is part of an evolutionary arms race, Frank adds. The termites hunted by the ants are unwilling to be carted off as food. So M. analis soldier ants often lose their legs to the sharp jaws of termite defense fighters. After having their lives saved, many of these wounded combatants are back on the hunt within a day, having figured out how to walk with fewer legs in the safety of the home nest.