Mosquitoes Genetically Modified in the Lab May Lead to Next-Generation Bug Repellents

Scientists have learned that by genetically modifying the way a mosquito responds to odors they can hinder the insects' ability to sniff out humans among other warm-blooded prey.

The researchers are calling the find one of the first successful attempts at genetically engineering mosquitoes and suggest that the work could pave the way to better understanding why mosquitoes are so attracted to humans and how to block that attraction.

In addition to being pests responsible for our itching and scratching through many a summer night, mosquitoes can also spread disease from human to human as they suck blood from different victims. Malaria, widely transmitted by mosquitoes, killed nearly 700,000 people worldwide in 2010, according to the U.S. Centers for Disease Control and Prevention.

Mosquitoes are attracted to humans for a number of reasons, including body heat and the carbon dioxide that we exhale, but "none of those factors would be as important as smell," said Leslie Vosshall, leader of the study and professor at Rockefeller University, who spoke with U.S. News & World Report.

Researchers were able to mutate the odor-detecting gene orco in the mosquitos' DNA, rendering the bugs incapable of distinguishing humans from guinea pigs.

"We knew this gene was important for flies to be able to respond to the odors they respond to," Vosshall said in a press statement. "And we had some hints that mosquitoes interact with smells in their environment, so it was a good bet that something would interact with orco in mosquitoes."

Vosshall said by disrupting that singe gene it could "fundamentally confuse the mosquito from its task of seeking humans." But she said as of now it's unclear whether the modified mosquitoes are unable to sense a "bad" smell from the guinea pigs, a "good" smell from humans, or both.

Next, Vosshall tested whether the orco-handicapped mosquitoes would be able to detect DEET, the chemical common in many mosquito repellents. When presented a human arm covered with a solution of 10 percent DEET and a bare human arm, the mosquitoes flocked toward both arms equally, suggesting they could not smell the DEET. But once they landed on the DEET-covered arm, the mosquitoes quickly flew away.

"This tells us that there are two totally different mechanisms that mosquitoes are using to sense DEET," said Vosshall. "One is what's happening in the air, and the other only comes into action when the mosquito is touching the skin." 

She said that if further research into how mosquitoes sense smells is successful then it might be of use in developing ideas for a next-generation mosquito repellent. 

Vosshall and her colleagues' research is published in the journal Nature.