How does DEET work? Study says it confuses insects

NEW YORK (AP) - For almost 50 years, people have used insect repellents containing DEET. But scientists still argue about how the stuff works.

Does it drive away mosquitoes and other insects by smelling bad to them? Or does it just confuse them so they can't smell their way to their targets? Finding the answer could help scientists design improved versions.

Now a study in fruit flies, published online Wednesday by the journal Nature, presents evidence for the confusion theory. Leslie Vosshall of Rockefeller University in New York and colleagues measured nerve signals that an insect's antennae send the brain to transmit information about odors. They found that the presence of the chemical DEET scrambles those signals.

They also report that a genetic mutation in one strain of fruit fly renders it insensitive to DEET and affects the odor-sensing machinery.

The research adds more evidence that DEET is a "confusant" rather than a repellent.

"It just scrambles whatever else they might be smelling," Vosshall said. But she said no single paper will really settle the debate.