Washington' July 17 - A chemical produced by male fruit flies and transferred to females during mating enables the female to tell other males to buzz off.

Harvard Medical School (HMS) researchers' along with German colleagues' discovered the chemical pheromone' which they named CH503.

The pheromone remains on the female's outer body after mating' warding off other male suitors for at least a week. This helps to account for previously noted mating behaviour in fruit flies that were earlier unexplained.

Researchers discovered the pheromone while using a new form of high-resolution laser mass spectrometry to scan distinct regions on the fruit flies' cuticle' or surface' said an HMS release.

Joanne Yew' at the time a postdoctoral fellow in the lab of HMS neurobiology professor Edward Kravitz' teamed with Klaus Dreisewerd and colleagues at the University of Munster in Germany for the study.

Their paper has been published this week in the journal Current Biology.