Mosquitoes Seeing Red

You want to prevent mosquito bites? Don’t wear red and stop breathing. That’s the gist of new research conducted at the University of Washington, published in Nature Communications.

The researchers put female Aedes aegypti mosquitoes – the purveyors of yellow fever, dengue, chikungunya, and Zika – through their paces. The bloodsuckers were placed in test chambers and prodded with specific odors and visual patterns, such as a colored dot or a human hand. Without the odor stimuli, the mosquitoes ignored the dots, regardless of color. When carbon dioxide – the gas we exhale with every breath – was applied, the ladies flew toward the dot if it was red, orange, black, or cyan. They ignored the colors green, blue, or purple.

Humans can’t smell CO2, but mosquitoes can. Previous research has shown that exposure to the gas boosts female mosquitoes’ activity level as they search for food (read: blood) in the spaces around them. The recent experiments reveal that CO2 also incites a preference for certain wavelengths in the visual spectrum, namely the redder end of it.

“Imagine you’re on a sidewalk and you smell pie crust and cinnamon,” said lead author Jeffrey Riffell in a UW news release. “That’s probably a sign that there’s a bakery nearby, and you might start looking around for it. Here, we started to learn what visual elements that mosquitoes are looking for after smelling their own version of a bakery.”

More research is needed to investigate how other visual and odor stimuli — sweat and other skin secretions, e.g. — help mosquitoes hone in on targets at close range. And we need to test other mosquito species too, since Aedes aegypti aren’t the only hemovores out for blood.

Photo credit: Riffell Lab