Mosquitoes more attracted to people who wear these colors

By Mark Waghorn via SWNS

Pesky mosquitoes are more attracted to people who wear red, orange or black clothes, according to new research.

But they are put off by those in green, purple, blue or white clobber, say scientists.

However you will need to cover up as they 'see' human skin of whatever color as red and home in on it.

It could help us steer clear of the critters that leave an itchy bite - and carry malaria and other deadly diseases.

The insects fly towards specific colors - once they have smelled a plume of CO2 from human breath.

After sniffing the gas they home in on particular hues that take their fancy.

Senior author Professor Jeffrey Riffell, of the University of Washington, Seattle, said: "Mosquitoes appear to use odors to help them distinguish what is nearby, like a host to bite.

"When they smell specific compounds, like CO2 from our breath, that scent stimulates the eyes to scan for specific colors and other visual patterns, which are associated with a potential host, and head to them."

Avoiding the bloodsuckers this spring and summer may hinge on the right choice of attire to cover your skin, say the US team.

They go for red, orange, black and aqua like cyan - ignoring other shades such as green, purple, blue and white.

The findings in Nature Communications shed light on why mosquitoes attack some individuals - and leave others alone.

Human skin, regardless of overall pigmentation, emits a strong red-orange 'signal' to their eyes.

The mosquito's sense of smell, or olfaction, influences how it responds to visual cues.

Knowing what lures the hungry pests also opens the door to developing better repellents, traps and other methods to keep them at bay.

Prof Riffell, a biologist, said: "One of the most common questions I'm asked is 'What can I do to stop mosquitoes from biting me?'

"I used to say there are three major cues that attract mosquitoes: your breath, your sweat and the temperature of your skin.

"In this study, we found a fourth cue: the color red, which can not only be found on your clothes, but is also found in everyone's skin.

"The shade of your skin doesn't matter, we are all giving off a strong red signature.

"Filtering out those attractive colors in our skin, or wearing clothes that avoid those colors, could be another way to prevent a mosquito biting."

The researchers tracked the behavior of female Aedes aegypti mosquitoes in a test chamber when exposed to visual and scent cues.

Like all mosquito species, only females drink blood. Bites from A. aegypti can transmit dengue, yellow fever, chikungunya and Zika.

Specific odors were sprayed. Patterns such as a colored dot or a tasty human hand were also presented.

Without any fragrance stimulus, the insects largely ignored the mark at the bottom of the chamber, regardless of color.

After a spritz of CO2, they continued to pay no attention if it was green, blue or purple.

But they headed straight for the dot when it was red, orange, black or cyan.

Humans can't smell CO2, which we and other animals exhale with each breath.

Mosquitoes can. Previous research has shown it boosts females' activity, making them explore surrounding space in search of a host.

The latest study revealed after sniffing the gas, their eyes prefer certain wavelengths in the visual spectrum.

It is similar to what might happen when humans smell something good.

Prof Riffell said: "Imagine you are on a sidewalk and you smell pie crust and cinnamon.

"That is probably a sign there is 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."

Most humans have 'true color' vision. We see different wavelengths of light as distinct colors.

For example, 650 nanometers shows up as red while 450 wavelengths look blue.

The researchers do not know whether mosquitoes perceive colors the same way.

But most of those the mosquitoes preferred - orange, red and black - correspond to longer wavelengths of light.

Human skin also gives off a long-wavelength signal in the red-orange range.

When the trials were repeated with human skin tone pigmentation cards, or a researcher’s bare hand, mosquitoes again flew toward the visual stimulus only after CO2 was introduced.

If filters removed long-wavelength signals, or a green-colored glove was worn, they did not.

Mosquitoes with a mutation needed to smell CO2 no longer showed a color preference.

Another strain of mutant mosquitoes, with a change related to vision so they could not 'see' long wavelengths of light, were more color-blind in the presence of CO2.

Prof Rifell added: "These experiments lay out the first steps mosquitoes use to find hosts."

More research is needed to determine how other visual and odor cues, such as skin secretions, help mosquitoes target potential hosts at close range.

Other mosquito species may also have different color preferences, based on their preferred host species. But the new findings add a new layer to mosquito control - color.