When it comes to assessing real estate, the house-hunting ant (Temnothorax albipennis) has a more pragmatic approach than does the average human. These 3-millimeter-long insects aren't comparison shoppers, new research using ants tagged with tiny radio transmitters shows, but rather have some strict ideas of what they are looking for. And when they find it, they don't get distracted by what may be around the corner; they move.
T. albipennis lives in the cracks in rocks, but just any old stone won't do. The ants look for nests that are dry and dark. Previous studies suggested that when their nest is destroyed, the ants comparison shop for a new abode: In the lab, scout ants that visited both a nearby, low-quality nest and a high-quality nest nine times farther away ultimately settled on the better nest and then alerted the rest of the colony to the new digs. It seemed that the scouts were comparing the two potential homes.
But the new study indicates that the ants follow a simpler rule to make their decision. Researchers led by behavioral ecologist Elva Robinson of the University of Bristol in the United Kingdom used an entomological pin to dot a bit of glue on an ant's thorax and then affixed a microtransmitter the size of a bit of glitter. The team attached these tags to every worker ant in nine colonies; each colony has between 100 and 200 workers and larvae. In the lab, Robinson's team simulated the ant's rock habitats with small stacks of glass and cardboard slides. She then destroyed their good homes by removing the top.
With their queen and larvae dangerously exposed, scouts set off in search of a new dwelling. As in the previous experiments, Robinson's team gave the ants two options: a nearby, low-quality home and a high-quality home nine times farther away. The majority of ants--about 75%--visited only one site and therefore could not be comparing them. Of the scouts that saw only the low-quality nest, 41% left after a short stay; in contrast, only 3% of the ants that visited the high-quality nest left. This suggests that the ants know what they're looking for--and after finding it, return to the old nest to recruit the rest of the colony to join them, the team reports online today in the Proceedings of the Royal Society B.
The findings suggest that "the ants don't bother with comparison shopping," says Robinson. "They simply evaluate a nest, and if it measures up, they accept it and move."
The study also sheds light on how ants reach a collective consensus, says Anna Dornhaus, a behavioral ecologist at the University of Arizona in Tucson. "Instead of needing to know all the alternatives, the ants only need to find one good nest and to stick to it." So, shoppers, follow the wisdom of the ants: If you spot something good, grab it.