Wise ant guides lead the way to a new nest
The tiny "house-hunting" ant Temnothorax albipennis lives in a fragile world, making its homes under tree bark and in rock crevices.
These homes are easily destroyed and whenever this happens the ants have to find a site for a brand new nest.
Scientists have now discovered that the ants rely on "knowledgeable" colony members that have explored the local area to guide them to a suitable spot.
The findings are published in the Journal of Experimental Biology.
End Quote Professor Martin Giurfa Paul Sabatier University
Their 'superior knowledge' allowed them to guide the group”
Dr Nathalie Stroeymeyt led the study at the University of Bristol's Ant Lab.
Dr Stroeymeyt is now based at the University of Lausanne, Switzerland, and she told BBC Nature that the results made it clear that the ants relied on "informed individuals" far more than was previously thought.
"Scientists had thought that the colony would collectively choose the best spot for a new nest without relying on individuals to make a choice," she said.
Dr Stroeymeyt and her colleagues devised a colourful experiment using tiny spots of paint to identify each ant in the colony and follow its behaviour.Ant arena
The team collected T. albipennis ant nests from their coastal homes in the southern UK, and relocated them to the lab in Bristol.
They built an "ant arena", which consisted of interconnected plastic dishes. One of the dishes housed the ants' nest and another, at the opposite end contained an identical, empty nest.
"We had motion-detection software, so every time an ant entered a nest, a picture was taken, and we were able to identify that ant," Dr Stroeymeyt told BBC Nature.
She and her team recorded the insects' movements as they investigated the empty nest and familiarised themselves with the surroundings.
"A week later we destroyed their nest," the researcher explained. At the same time, she placed another brand new nest elsewhere the arena.
"We wanted to see whether they would go to the nest they had already had chance to investigate - the familiar nest - or the new one," said Dr Stroeymeyt, " and if they relied on particular individuals to find a new spot."
While some of the insects scampered off in all directions, a few individual ants ran straight to the familiar alternative nesting site.
These same scout ants, which had been investigating the arena from the outset, returned quickly to the devastated nest to recruit more of their nest-mates, sometimes carrying them to the new site.
The scouts would return to the destroyed nest repeatedly, enlisting more followers.
Professor Martin Giurfa from Paul Sabatier University in Toulouse, France, who was also involved in the study, said that these "informed individuals" led the collective migration of the whole colony.
"They acted as opinion-leaders based on the information they have acquired from the environment, " Prof Giurfa explained. "Their 'superior knowledge' allowed them to guide the group."
Professor Susanne Foitzik, an ant expert from Johannes Gutenberg University of Mainz, Germany, said the results were not surprising.
Ant communities "generally show a division of labour among their workers - some ants specialise in certain tasks," she told BBC Nature.
But, she added, "this study does greatly contribute to our understanding of the organisation of ant societies".