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The sex of an entire ant colony is determined by the queen

Ant mating is very different from the experience of humans and other mammals. Formica ants seasonally take to the air in dizzying flights where males and females join in aerial coupling. The males soon die after these forays, while the females land, chew off their own wings and go about the business of creating new ant colonies.

The females can carry the sperm from their short tryst with the males for a decade to help grow their colony. Scientists have long known that queens can produce broods entirely male or female, although the mechanism has remained elusive. 

“It’s weird to have any parent that’s only producing one sex or the other,” explained Jessica Purcell, an entomologist at the University of California Riverside (UCR).

A new study led by Purcell reveals that female ants carry two copies of a sex determining chromosome while males carry only one copy. This means to create males, the female can simply lay unfertilized eggs or control the sex with her genetics. 

“Male ants develop from unfertilized eggs their mother lays,” said study senior author Alan Brelsford. “Therefore, male ants, as well as bees and wasps, genetically have a mother but no father.” 

The colony sex ratio can also be manipulated by starving certain larvae or killing them directly. Sometimes, the availability of food is a factor in the sex ratios of a colony. “When extra food is dumped on a colony, it produces fewer males,” said Brelsford,

The researchers want to more thoroughly explore how these genetics work in different habitats throughout the ant’s range. Such research they hope could help North American ants, which tend to coordinate their mating flights with different seasons and temperatures.

The scientists worry that climate change could have a negative impact on native ants, which are important to ecosystems. “Ants are really integral to ecosystems as one of the most abundant insects,” said Purcell. “Gardeners tend to love earthworms, but ants do similar things to enhance soil health.”

The research is published in the Proceedings of the National Academy of Science

By Zach Fitzner, Staff Writer

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