All are queens: the ant species without males or workers

A parasitic ant species from Japan is the first ever found to have done away with both male and female workers – instead, each individual is a queen trying to take over the nests of other species.

Ant colonies typically consist of a queen, female workers and short-lived males that die after mating.

For more than 40 years, scientists have suspected that the rare parasitic ant Temnothorax kinomurai produces only queens, but until now there has been no definitive proof.

Young queens of this parasitic species take over the nests of a related species, Temnothorax macorakill the host queen and some workers by stabbing them. They then reproduce asexually, producing cloned offspring in a process called parthenogenesis, which is rare in ants but common among some other insects. The T. makora workers are tricked into helping raise the young T. kinomurai queens.

Jürgen Heinze at the University of Regensburg, Germany, and his colleagues collected six colonies with T. kinomurai queens and raised them in artificial nest boxes in the laboratory. From these colonies, they were able to breed and raise 43 queen offspring in the laboratory. Inspection of their genitalia confirmed that there were no males.

These 43 queens were then given the opportunity to take over colonies of T. makora. Seven queens survived and succeeded in their coup attempts. They produced another 57 offspring, which were again confirmed to be all female queens.

“They show a completely new form of social organization, and add another exciting dimension to the already rich and varied world of ants,” says Heinze.

Invading colonies of other species is a risky strategy, as shown by the high queen failure rate seen in this study. But if all your offspring are queens, you have more chances to start new reproductive colonies.

“If the parthenogenesis develops due to random mutation, as in T. kinomuraiqueens can produce 100 daughters, who do not need to mate – therefore there are 100 queens trying to found a new colony,” says Heinze. “It is clear that the success rate of parthenogenetic queens is higher than that of sexual queens.

“This species can be considered the last step in the evolution of social parasitism, highlighting the enormous flexibility in the life histories of social insects,” he says.