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How do moths choose their flowers?

A foraging hawkmoth. Manduca sexta moths use their sense of smell to locate and discriminate between innately attractive flowers, but they also have the ability to learn - through olfactory conditioning - to utilize other nectar resources.

[Image courtesy of Charles Hedgcock, Department of Neuroscience at University of Arizona, and Jeff Riffell, Department of Biology at University of Washington]

Have you ever wondered how moths know which flowers to visit for nectar? A new study shows that a particular kind of moth—the hawkmoth—has specific patterns of brain activity for flower odors that it is naturally attracted to. On top of that, these moths can learn to associate new odors with nectar without forgetting their original, natural preferences, according to researchers.

Jeffrey Riffell and colleagues studied what happens in hawkmoths' brains when the insects are foraging for nectar. They discovered that most of the flower odors that hawkmoths are naturally attracted to contain the same chemicals. These flowers might have evolved similar scent signals over many generations in order to attract hawkmoths, they say.

The researchers also suggest that the moths' ability to learn new scents is controlled by a compound known as octopamine, which alters the activity of neurons in the animals' brains. These findings mean that hawkmoths have two different odor pathways—one that is tied to flower odors that hawkmoths are naturally attracted to and another that is dedicated to learning new smells.