Termites: In Asexual Colonies, Females Can Reproduce Without Males

"There may be evolutionary advantages to asexual reproduction."

Termites form complex societies like bees and ants do, but with a crucial difference: Unlike the mostly-female bee and ant colonies, termites usually have a 50/50 mix of males and females. A king and queen reign over the termite colony, getting busy and producing offspring worker termites in a roughly equal mix of males and females. But occasionally, some lady termites don’t need dudes at all.

In a paper published in the journal BMC Biology on Tuesday, a team of researchers from the University of Kyoto, Japan, and the University of Sydney, Australia, presented evidence of termite colonies made entirely of females. The individuals in those colonies reproduce asexually, hatching from eggs that have never been fertilized. The species, a Japanese dry-wood termite known as Glyptotermes nakajimai, lives on many of Japan’s islands, but the study’s authors found all-female colonies only on two of them: Shikoku and Kyushu.

“Our paper is the first demonstration that termites can do away with males completely by the evolution of an asexual lineage, and get along fine just with females,” Toshihisa Yashiro, Ph.D., a postdoctoral researcher at the University of Sydney and the study’s first author, told Newsweek.

In all-female termite colonies (left), there are multiple queens (Q). In typical termite colonies (right), there's a king (K) and a queen, who are the parents of all the others. Additionally, the queens in the asexual colonies had empty spermathecae, the pouches used to store sperm after mating.

Yashiro et al

The researchers sampled termites from 74 mature colonies and analyzed the sex distribution in every one. On Honshu — Japan’s largest island that’s home to Tokyo and Kyoto — and on the islands of Amami-Oshima, Okinawa, and Ogasawara, the 50/50 sex balance usually observed in termites was intact. But on Shikoku and Kyushu, the colonies were 100 percent female, leading researchers to suspect that these colonies arose from a single occasion of evolution.

Previously, all-female societies like this had only been observed among the order of insects known as Hymenoptera, which includes bees, wasps, and ants. But the new paper provides evidence that termites, which belong to the order Blattodea along with cockroaches, exhibit the same pattern.

The single-sex termite societies seem to be getting along just fine without males, the researchers write. In fact, there may be evolutionary advantages to asexual reproduction.

“We have shown that asexuality acts as a stabilizer of soldier head size, which we hypothesize is beneficial for efficient phragmotic defense in termites,” the study authors write. Phragmotic defense is the practice of an animal defending its burrow with its own body. It’s possible that all soldiers having the same head size could help the worker termites build standardized tunnels just wide enough for soldiers’ heads. This way, the researchers hypothesize, the soldiers may have a higher likelihood of successfully blocking their tunnel from invaders.

Although the researchers have yet to test this hypothesis, the thoroughness of their sampling and investigation indicates that these findings are not a fluke. Rebeca Rosengaus, Ph.D., an insect sociobiologist at Northeastern University who was not a part of the study, told Smithsonian that the study’s authors’ work was “very comprehensive.”

“No study in the past [has described] a complete elimination of males,” she said. “That is completely new and exciting.”

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