This Fake Skin Fools Mosquitoes—to Fight the Diseases They Spread

The setup looked the part, but would it work? The researchers devised a simple test: In one enclosure, they placed hydrogels coated in DEET. Gels in another received a plant-based repellent that smells like lemon and eucalyptus. Gels in the third got no coating. Then they let a couple dozen mosquitoes loose around each fake skin for up to 45 minutes. 

Cameras collected video inside each enclosure to record the insects’ behavior and count how many fed until they were full. That's a lot easier to do when the test subject is a gel, and not an animal, who will move to shoo the insect away, disrupting its meal. “In this system, nothing's moving,” Wesson says. “And so once they start feeding, they would typically feed till they're completely engorged.” 

The results were clear: Only the mosquitoes offered the uncoated hydrogels fed on blood. None of the mosquitoes offered gels with either repellent fed at all. This demonstrated that the hydrogels mimicked skin well enough to entice mosquitoes to feed, and that they behaved as normal when repellent was involved.

To Wesson, the platform opens new avenues to study how mosquitoes spread deadly diseases. For instance, entomologists know that mosquito saliva somehow intensifies disease transmission. New experiments with the hydrogel setup could help pinpoint a saliva protein that’s most responsible for the effect. A vaccine or repellent could then target that protein and slow infections, she says.

The platform could also be useful in efforts to genetically engineer mosquitoes that are less attracted to the scent of humans and release them to replace wild species, says Ross. “Before you do any of those field releases, you have to evaluate those mosquito strains in the lab,” he says, and these hydrogels could help researchers select the best mutants.

Ross cautions that the system isn’t a perfect skin mimic. “Mosquitoes are really complicated creatures, and they're very good at hunting you down from a long distance,” he says. They use carbon dioxide, body odors, humidity, visual contrast, and even color to pick targets. “Unless you add in all the other cues that attract mosquitoes, you're not going to get the full effect.”

Still, he feels that while hydrogels may not replace human trials for testing repellents, they could be used to elevate promising candidates without involving people or animals. “The better ones would still rise to the top,” Ross says.

“We're at the basic level right now,” says Wesson. The study is just a proof of concept, but, she continues, “We hope that we could get to the point where it'll be a springboard for narrowing down those choices and making it less expensive.”