Mosquitoes may learn to like DEET, a common insect repellent

Pesky mosquitoes on the hunt for blood may find the smell of a common repellent attractive, not repulsive. That’s the finding of new lab tests.

The chemical is known as DEET. It’s been one of the most effective insect repellents for decades. But in new lab tests, yellow-fever mosquitoes (Aedes aegypti) exposed to DEET learned to associate the chemical with food. This suggests these insects can link unpleasant odors with rewards. That turns a bad experience into an inviting one.

For now, it’s not clear if this might happen outside the lab, too.

How DEET works, exactly, is a bit unclear, says Clément Vinauger at Virginia Tech in Blacksburg. He studies animals’ brains and behaviors. Some studies have suggested mosquitoes don’t like DEET’s smell or taste. Others hinted that the repellent scrambles mosquito senses. That would keep the insects from detecting the otherwise enticing body odors that normally lure them in for a blood meal.

The new results suggest that mosquitoes do detect DEET, Vinauger says. They also can learn, changing their behaviors based on prior experiences.