While mosquitoes are mostly just a nuisance in North America, they remain one of the world’s deadliest disease vectors. So when a significant breakthrough in repelling these insects occurs, that’s good news not just for hikers in Alaska and airboaters in the Everglades, but for the millions of people around the globe threatened by malaria, West Nile virus, dengue fever and other mosquito-borne pathogens.
Associate Professor of Entomology Anandasankar Ray’s work — initially funded by both the Bill and Melinda Gates Foundation and the National Institutes of Health — has made such a breakthrough. His discovery of chemical compounds that block mosquitoes from detecting carbon dioxide — their main method of tracking their prey — has led to the development of a wearable patch that essentially makes humans invisible to mosquitoes. Called the Kite Mosquito Patch, and created by Olfactor Laboratories Inc., the product started field trials this summer, to much media fanfare. And Ray says it all began, as so many discoveries do, with the humble fruit fly Drosophila melanogaster.
“In 2008, we were curious about how fruit flies behave towards carbon dioxide emitted by fruit,” Ray recounts. “We found that ripening fruits have simple odor molecules that can block the fruit fly carbon dioxide receptor proteins. That was the first step.”
Ray and his team realized that mosquitoes use these same receptors to track their prey. “When living beings breathe, they exhale large quantities of carbon dioxide. This can be tracked from a distance by mosquitoes,” he says. “Mosquitoes can smell carbon dioxide and they just love it! Our breakthrough moment was that we could interfere with that process of using simple odors.”
They soon discovered scent compounds that blocked those receptors in mosquitoes—but they smelled kind of bad. “Our first batch [the topic of a 2011 cover story in the journal Nature] smelled too buttery, like bad body odor.”
“The next step was to train a computer to identify the properties of the compounds we had already discovered and then us that to screen hundreds of thousands of compounds,” Ray says. “We test compounds with electrophysiology, and once they fit both criteria, then we do behavior analysis of mosquitoes.” And the scent of the compounds? “Some of them smell minty, some of them smell like chocolate. We perceive it as pleasant, but the mosquito is not so happy with it.”
The next step was to set up a company dedicated to insect research, one that could identify the best odors for behavior control and design products to protect people from mosquitoes. Ray founded Olfactor Laboratories Inc. in 2010, with help from UCR and the Innovation Economy Coroporation. He recruited Ph.D.s from the university.
The Kite Mosquito Patch is the company’s first product. The completely nontoxic, wearable patch is projected to hit the market in a year, after a testing process in Uganda. The patch comes in a variety of colors, is worn on clothing rather than skin and is being designed to provide 24 hours of protection. Other potential delivery systems abound. “These are odors that could one day go into perfumes, a plug-in dispenser, or even be embedded in your laundry detergent,” Ray says.
Ray has also come up with compounds that produce the opposite effect: They attract mosquitoes y mimicking carbon dioxide. This technology is being developed into traps. “Traps that you can get at Home Depot right now, they have a giant tank of propane that is used to burn and create carbon dioxide, which is what lures the mosquitoes,” Ray says. “The next generation would not use carbon dioxide, but mimics of carbon dioxide. The vision is to try to get this to work in developing countries where diseases are real fears—malaria in Africa, dengue in India, Brazil, China.”