Unusual ancient gene governs sex of ant, bee, wasp newborns Premium

Discover how an ancient gene influences the sex of ant, bee, and wasp embryos, impacting conservation and breeding practices.

In many animals, sex is decided by obvious physical differences in the chromosomes. But in ants, bees, and wasps, sex is often decided in a more unusual way: by whether an embryo carries two different versions of a specific DNA region or two matching ones.

Two studies, one in Science Advances in 2024 and the other in Proceedings of the National Academy of Sciences in January 2026, have shown that this rule is controlled by a stretch of DNA that doesn’t even make a protein — and that the same basic setup has persisted across an unusually large span of evolutionary time.

The finding could be used to more closely monitor the diversity of these insects.

The 2024 study focused on the Argentine ant (Linepithema humile), an invasive species. The researchers were motivated by a gap in what biologists know about sex determination in most insects: they understand some famous examples, like fruit flies, but many economically and ecologically important insects, including the 1.2 lakh species of ants, bees, and wasps, use methods whose core molecular triggers have been hard to pin down.

In these insects, females usually develop from fertilised eggs and have two chromosome sets while males usually develop from unfertilised eggs and have one. Sometimes, however, fertilised eggs produce diploid males, males with two chromosome sets, and they’re typically sterile. This is bad news for colonies and for species that are bred commercially or are trying to survive in the wild.

To find the genetic switch behind this method, the 2024 team compared DNA patterns in female ants and diploid males produced by inbreeding. They found a single small region in the genome where females were consistently ‘mixed’, i.e. carried two different versions, while diploid males were consistently ‘matched’, carrying two copies of the same version. In other words: being ‘mixed’ at this spot reliably predicted female development and being ‘matched’ predicted male development.