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New research has found that smelly armpits may turn some people into a mosquito magnet. [nypost.com]
This is apparently the reason that some people are so plagued by the annoying critters — while others get off scot-free, according to scientists.
The pesky insects are drawn to body odor, also known as BO — and mosquitoes can find us from 350 feet away once they get a whiff, according to SWNS, the British news service.
Mosquitoes can also carry deadly diseases.
The new findings are based on the African malaria mosquito Anopheles gambiae, which was let loose in an ice rink-sized outdoor testing arena in Zambia.
Said the study’s lead author, Dr. Diego Giraldo, a neuroscientist, “This is the largest system to assess olfactory preference for any mosquito in the world. And it is a very busy sensory environment for the mosquitoes,” as SWNS reported.
The team from Johns Hopkins University in Baltimore, Maryland, released 200 hungry mosquitoes each night and used infrared motion cameras to observe how often they landed on evenly spaced pads heated to 35ºC — mimicking human skin, the report said.
It was a good sign they were ready to bite. [nypost.com]
Body odor was apparently a more attractive bait than CO2 — a known cue for mosquitoes.
But further tests showed that the swarm of 200 individuals were also choosy. The aromas of six volunteers sleeping in surrounding single-person tents were piped onto the pads over six consecutive nights.
It enabled the researchers to record the mosquitoes’ preferences and collect nightly air samples from the tents to compare airborne components of body odor.
Senior author Dr. Conor McMeniman, a vector biologist, said, “These mosquitoes typically hunt humans in the hours before and after midnight,” as SWNS also reported.
“They follow scent trails [nypost.com] and convective currents emanating from humans, and typically they will enter homes and bite between around 10 p.m. and 2 a.m.”
He added, “We wanted to assess mosquito olfactory preferences during the peak period of activity when they are out and about and active — and also assess the odor from sleeping humans during that same time window.”
Night after night, some people were more attractive to mosquitoes than others, the study found.
One volunteer, who had a strikingly different odor, consistently attracted very few mosquitoes, the study noted.
The study also identified 40 chemicals that all of the humans emitted — though at different rates.
Said lead co-author Dr. Stephanie Rankin-Turner, an analytical chemist, “It is probably a ratio-specific blend they are following … We don’t really know yet exactly what aspect of skin secretions, microbial metabolites or breath emissions are really driving this, but we are hoping we will be able to figure that out in the coming years.”
People who were more attractive to mosquitoes consistently emitted more carboxylic acids produced by skin microbes, the study said.
By contrast, the person who was least attractive to the mosquitoes gave off fewer acids but triple the amount of eucalyptol, a plant compound.
It is found in oils, herbs and spice — and elevated levels may be related to diet.
The researchers were surprised by how effectively the mosquitoes could locate and choose between potential human meals within the huge arena, SWNS noted.
Dr Rankin-Turner added, “When you see something moved from a tiny laboratory space where the odors are right there, and the mosquitoes are still finding them in this big open space out in a field in Zambia, it really drives home just how powerful these mosquitoes are as host seekers.”
The study was published in the journal Current Biology.
It could lead to the development of more effective repellents and traps, noted SWNS.