The University of Georgia researchers said after the flies hatch from eggs laid inside overripe, young fruit, the flies feed on the sugar-rich fruit. As they mature, however, they stop eating, leave the fruit and burrow into the earth, where they grow into flies that will eventually lay their own eggs.

The scientists said they discovered that the switch from food attraction to food aversion is controlled by a timing mechanism in the fly's brain and its sensory system.

"What we found was that a molecular timing switch tells them when to quit eating and burrow into the earth," said Assistant Professor Ping Shen. "We also found that the same switch can trigger strong cooperative behavior in the flies."

The authors said the system has a counterpart in mammalian models implicated in the response to food and alcohol and the suppression of anxiety and pain. Understanding that system in the fruit fly could, possibly, lead to the development of more effective pain relievers with fewer adverse events for humans, they said.

The study appears in the journal Nature Neuroscience.