Glow-in-the-dark mosquitoes could soon help explain what makes the human scent so darn appetizing.
In his lab at Johns Hopkins University, Conor McMeniman is genetically engineering mosquitoes so that their brains glow when they have a strong positive or negative response to chemicals that make up human odor. It should help determine why mosquitoes, particularly those that carry the Zika virus, malaria and other devastating diseases, can’t get enough of our arms, legs and ankles.
The project was just awarded a grant from the U.S. Agency for International Development, which recently called on innovators to propose ways for the government to combat Zika. His research could allow agencies, nonprofit organizations or companies to develop low-cost traps that capture and kill mosquitoes in an effort to control the population.
“It’s really a new direction in our research where we’re trying to understand how the mosquito brain perceives human scent,” McMeniman said. “We’re trying to figure out what part of the chemistry is actually driving their attraction to humans.”
Sure, the mosquito brain is microscopic and less advanced than ours. But McMeniman explains that mosquitoes have a sophisticated mechanism called the antennal lobe that detects odors in the environment and funnels that information to regions of their brain that decide when it’s time to mate or feed. It gives mosquitoes an “exquisitely attuned sense of smell,” he said.
And certain species of mosquitoes specifically lust after the smell of humans. Those same species also happen to transmit diseases like Zika, dengue fever and malaria. “If you give them the choice between human scent and animal scent, they will always go toward the human smell,” McMeniman said. Glorious.
The science of humankind’s scent isn’t new. Researchers have long studied and catalogued the hundreds of chemicals humans emit aromatically. They’ve identified some, such as the carbon dioxide in our breath and lactic acid in our sweat, that send mosquitoes into a tizzy. The human-scented traps currently on the market, and there are some out there already, mostly exploit mosquitoes’ attraction to these smells.
But McMeniman said that our understanding is still relatively simple. The project at Johns Hopkins aims to test the hundreds of chemicals we emit to isolate those scents that are uniquely human and that most appeal to disease-harboring mosquitoes. While the project is still in the very early stages, McMeniman’s goal is to create a refined cocktail of chemicals that is a near replica of the human aroma.
“As you might expect, it’s quite a complex problem,” McMeniman said. “You have hundreds of chemicals potentially being released. Humans being humans, we vary in our diets, our genetics, our application of fragrances on our skin, such as deodorants or perfumes.”
Once the lab has identified the right mix of chemicals, they can be used to lure mosquitoes into traps.
Just don’t expect a line of human-scented products to follow. Candles, bath soaps and air fresheners that smell like humans are possible, if kind of gross, but McMeniman’s creation isn’t something your nose will be able to detect.
“The lure we’re trying to develop hopefully won’t be perceptible to us,” he said. “Insects have this very finely tuned sense of smell, probably several orders of magnitude better than our sense of smell.”
Read more from The Washington Post’s Innovations section.