The findings are more than academic: The researchers hope to develop methods for using trained moths to detect odors of interest for defense industry and law enforcement such as odors given off by biological and chemical weapons.

Animal behaviorists have historically argued that most insects have a programmed response to a variety of situations, such as knowing which odors signal the presence of food and mates.

But scientists are discovering that animals don't always instinctively know what to do. In these cases, they have to learn, said Kevin Daly, the study's lead author and a research scientist in entomology at Ohio State University.

He and his colleagues used tiny electrodes implanted in the heads of sphinx moths to continuously monitor the insect's neuronal activity and feeding behavior before, during and after training the animal that one odor meant food sugar water was on the way and another odor did not.

"We saw a dramatic restructuring of the neural networks that convert scent into a code that the rest of the brain can understand," Daly said. "The changes in this coding suggest that the moths learned to differentiate between an odor that meant food and an odor that didn't."

Understanding how moths detect and discriminate between scents could have wide-reaching applications. In related work, Daly and his colleagues are training moths and bees to detect odors from manufactured explosives.

"In principle, if we can understand how insects learn and distinguish between odors, we could 'train' these animals to recognize any detectable odor of interest," he said.

The findings currently appear online in the Proceedings of the National Academy of Sciences.

The electrodes placed in the moths'
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Contact: Kevin Daly
Daly.40@osu.edu
Ohio State University
12-Jul-2004