A parasitic ant species from Japan, Temnothorax kinomurai, has been confirmed to produce exclusively queens, with no males or workers. Researchers found that these queens reproduce asexually and invade colonies of related species to raise their offspring. This discovery reveals a novel form of social organization in ants.
In a study published in Current Biology, scientists have documented the unique reproductive strategy of Temnothorax kinomurai, a rare parasitic ant native to Japan. For over 40 years, experts suspected that this species lacked males and female workers, but recent lab experiments provided definitive evidence.
Jürgen Heinze at the University of Regensburg in Germany, along with colleagues, collected six colonies of T. kinomurai queens and reared them in artificial nest boxes. From these, they raised 43 offspring, all confirmed as queens through inspection of their genitalia—no males were present. These queens were then tested on colonies of the related species Temnothorax makora. Seven of the queens succeeded in taking over the host nests by stinging and killing the resident queen and some workers. The duped T. makora workers then helped raise the invaders' young.
The queens reproduce via parthenogenesis, a form of asexual reproduction where offspring are cloned females. This process, though rare in ants, allowed the successful queens to produce another 57 offspring, again all queens. Heinze noted, “They exhibit an entirely new form of social organisation, adding another exciting dimension to the already rich and varied world of ants.”
This strategy carries risks, as evidenced by the low success rate of the queen invasions. However, producing only queens increases opportunities for establishing new colonies without the need for mating. Heinze explained, “If parthenogenesis evolves due to random mutation, as in T. kinomurai, queens can produce 100 daughters, which do not need to mate—hence, there are 100 queens that try to found a new colony.” He added that the success rate of these parthenogenetic queens appears higher than that of sexually reproducing ones.
Heinze described T. kinomurai as “the final step in the evolution of social parasitism, highlighting the enormous flexibility in the life histories of social insects.” The findings underscore the diverse adaptations in ant societies, where typical colonies include a queen, female workers, and short-lived males that die after mating.