In this parasitic species, all ants are queens and reproduce by cloning themselves and hijacking colonies of other ants.

Scientists have discovered that a rare type of ant that lives in Japan has no males or workers, only a queen ant. These ant queens parasitize the nests of another species of ants and reproduce asexually, creating clone queens that take over other nests.

Jürgen Heinze, a biologist at Germany’s University of Regensburg and co-author of the new study describing the discovery, said the parasitic ant Temnothorax kinomuroi is “the first known species to have only a queen.”

Most ants live in orderly, close-knit societies where the queen retains the sperm cells from mating before forming a colony. They selectively use these sperm cells to either lay fertilized eggs that become female workers or queens, or unfertilized eggs that develop as short-lived males.

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However, there are also parasitic queens who invade colonies of other species and take over them, often forcing their workers to serve and raise offspring until their own brood takes over.

Keiko Hamaguchi, a biologist at the Kansai Research Center in Kyoto, and her colleagues have been studying T. kinomuroi, which is found in just nine locations in Japan. It was thought that the ants behaved differently and produced only queens, without workers or males, but no one knew for sure.

Young queens of T. cynomurai invade the nests of the closely related species Temnothorax macora and sting the host queen and the most aggressive worker bees that attempt to stop the coup. If the takeover is successful, the surviving workers will raise the alien queen’s children.

“T. kinomuroi requires host workers for foraging and rearing, and cannot reproduce without them,” Heinze told Live Science in an email.

To find out what was going on, Hamaguchi’s team collected six colonies run by T. kinomuroi queens and kept them in hives in the lab. From these colonies, they raised 43 offspring, none of which were male, according to examination of their reproductive organs and workers. All were queens.

When presented with a colony of T. macora that could serve as a new host, seven of the 43 unmated offspring made a successful coup attempt. This is consistent with the typically high failure rate of the risky undertaking of establishing a parasitic colony. The seven queens produced a total of 57 offspring, all of whom were also queens. The research results were published in Current Biology on February 23.

Queens of some ant species can clone themselves by asexual reproduction known as parthenogenesis. Other ants use social parasitism, hijacking the labor force of unrelated colonies to raise their own offspring.

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“However, despite the intuitive evolutionary logic behind such a combination, so far no species has been shown to fuse both strategies,” Jonathan Lomiguier, an evolutionary biologist at the University of Montpellier in France who was not involved in the study, told Live Science via email.

“This is highly unusual considering there are over 15,000 species of ants,” added biologist Daniel Cronauer of New York’s Rockefeller University.

The benefits of sexual and asexual reproduction are usually held in a delicate balance, he said. Asexual reproduction allows an organism to maximize its genetic contribution to the next generation by producing genetically identical daughters, and asexually reproducing species can often outperform sexually reproducing species because they do not need to invest energy and resources in finding mates or producing males.

However, sexual reproduction produces genetically diverse workers, which could be beneficial to ant colonies in terms of pathogen defense and division of labor.

But given that T. kinomuroi queens no longer produce workers, these advantages disappeared, Cronauer told Live Science. “This could shift the balance in favor of asexual reproduction and ultimately lead to the loss of males,” he said.