‘Godmother’ ant uses Mob tactics to rub out rivals

Researchers at the University of Sheffield and the University of Keele have discovered that Dinoponera quadriceps ants, known as Dinosaur ants, and the Mafia have something in common. Both have dominant leaders who give rivals a “kiss of death”, as a signal for their ‘mob’ to punish the offender. The alpha female in a colony of Dinosaur ants marks rival females with a chemical which signals lower ranking ants in the colony to punish the “pretender”. This secures the alpha female’s position as the only breeding female within the colony.

Dinosaur ants, from Brazil, are the world’s largest ant, at about 3 to 4cm long. They live in small colonies, with only one breeding female. This female is the ‘mother ant’ and all the other ants in the colony are normally her daughters. Male ants play no active role in colony life. Dinosaur ants are different from most other ant species in that the alpha ant is not a queen, but a mated worker. This means that any female can potentially become the alpha ant, leading to increased rivalry within the colony compared to normal ants.

Francis Ratnieks, Professor of Apiculture at the University of Sheffield and one of the authors of the study says, “If the mother ant has her position threatened by another female (usually the next highest ranking ant, known as the beta female) she will wipe her sting against the pretender, leaving behind a distinctive chemical mixture. On detecting the scent, lower ranking females will punish the beta female. This punishment (known as immobilization) leads to the beta female losing her high rank and any chance of replacing the alpha in the future. Sometimes the punishment kills the rival.”

Thibaud Monnin, formerly of Sheffield University and now at the Université Pierre et Marie Curie in Paris, stresses that low ranking females have a lot of power. “They cannot reproduce but, depending on their best interest, they can either allow the pretender to take over the alpha position. They prevent replacement when alpha is young and fertile, and favour replacement when alpha is getting old, so low ranking females choose the breeder of the colony.”

Professor Ratnieks says, “This study shows that ants can have similarities to humans in that both police their societies in order to prevent undesirable behaviour.”