4:16pm

Thu September 29, 2011
The Salt

Scent Of Rotten Fruit Signals Sex, At Least For Fruit Flies

If you're into sexual chemistry, set an aging banana peel or apple core out on your kitchen counter, pull up a chair, and wait — for the fruit flies.

If you are squeamish about the fruit you eat, you may want to stop reading here. Otherwise, here's the skinny about fruit flies: They like to mate ON fruit. Or whatever else that's on the fruit-fly version of the nutrition pyramid (or whatever geometric thingie the USDA is shoving its food groups into nowadays). Editor's Note: Chris, it's a plate. Try to keep up.

Scientists certainly knew about the fruit fly's mating rituals. But now they think they know why they're into fruit so much. It's the smell.

Female fruit flies produce pheromones — biochemicals that affect behavior in lots of insects and animals too — to attract males. But researchers have discovered that the brain circuits in male fruit flies that detect the female's come-hither chemical are activated FIRST by aromatic chemicals in fruit. (OK, if you have to know, it's phenylacetic acid and phenylacetaldehyde in the fruit.)

Why is this? Well, usually there's some good reason for complicated animal or insect behavior (unlike most human behavior, I'm afraid). In this case, researchers led by Richard Benton at the University of Lausanne in Switzerland, say it's to the fruit flies advantage to mate where they eat. It offers an immediate and beneficial place to lay eggs. They're born in a horn of plenty.

People have been known to use food as an aphrodisiac, too. Food won over Albert Finney in the movie Tom Jones, and cast a spell on an entire town in Like Water For Chocolate.

If you want to read more about fly love and the importance of food, you can read all about it in this week's issue of the journal Nature.

Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.