Mosquitoes bite you and others don't? The secret is in the smells

Mosquitoes bite you and others don't?  The secret is in the smells

Are you a mosquito magnet? Human body odor and biochemical characteristics make some people more prone to bites. At best, the sting will just leave you with an itchy red bump. But mosquitoes are still one of the deadliest vectors in the world today, and that's why understanding what draws them to us could save up to half a million lives a year.

Of the more than three thousand mosquito species in the world, only a small number have evolved to suck human blood. About sixty of them live in Italy, but only the females of six species sting us. The degree of reaction to a sting varies from person to person, and inevitably leads some to feel more targeted than others. Several studies have found that this is indeed the case. There are attractive factors that make some humans more 'succulent' than others.

Let's immediately clarify that the "sweetness of the blood", or the presence of sugars, has absolutely nothing to do with it: the attraction towards us depends on the amount of carbon dioxide we emit, how much we sweat, what we ate and drank , the color in which we are dressed and the carboxylic acids produced by the bacteria that live on our skin.

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I study

A study just published in Current Biology confirms what has already been hypothesized from a previous one published on cell, or the ability of mosquitoes to smell us and use it as a navigator to find and sting us. To understand how mosquitoes choose their prey, researchers at Johns Hopkins University set up a structure the size of an ice rink into which they pumped various human body odors and a carbon dioxide hood to mimic a sort of densely packed dormitory. populated.

Mosquitoes controlled with cameras

Then they monitored the mosquitoes with infrared cameras to see how they prowled in front of the rich buffet in search of their favorite prey. The results left no doubts: all the mosquitoes were more attracted to the carboxylic acids present in the air, including butyric acid which gives the typical smell to aged cheeses. On the contrary, it was not citronella but eucalyptol that discouraged the mosquitoes the most.

'This discovery opens up new approaches for developing baits or repellents that can be used in traps to disrupt host seeking behaviour,' explains Dr Edgar Simulundu, author of the study which aimed to find solutions against "malaria vectors in regions where the disease is endemic". It is no coincidence that this mosquito-borne disease is responsible for over 600,000 deaths a year, mainly in children under the age of 5 and also in pregnant women.

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The first peak in early June

But what mosquito season will we experience this year? "It is too early to tell, but it is likely that the first peak of the year will occur in early June in Northern Italy - explains Igor Boni, agronomist of the Ipla, responsible for the mosquito control plan of the Region Piedmont - Due to the prolonged drought, last year we thought there would be a reduction in outbreaks, but it was still an average year across the peninsula.This is due to the fact that mosquitoes lay their eggs where the water is stagnant and many dry streams had created puddles which proved to be an ideal habitat".

The strategy

According to Boni these are the first crucial days for the fight against mosquitoes, which "must take place in the larval stage, when they are still in the water". "There are actions to reclaim public places throughout Italy, as we at Ipla carry them out in Piedmont - he recalls -. But 70% of outbreaks occur on private land, so we should all be careful and preventative".

The most aggressive

In Italy, the best known for their aggressiveness, abundance and diffusion are the Aedes albopictus, the tiger mosquitoes, followed by the Ochlerotatus caspius which mainly develop in rice fields, and by the Culex pipiens which sting at sunset. "What few people know is that tiger mosquitoes do not move more than a hundred meters from where they were born, so if we have them at home it is very likely that they were born thanks to us - explains the expert -. They also have the peculiarity of be attracted much more by black than by white. So, if you have your legs uncovered and you wear a dark sock, expect pain in your ankles. Tiger mosquitoes bite during the day, tend to fly almost close to the ground and know how to camouflage well; common mosquitoes , on the other hand, are the ones that we hear ringing in our ears at night". Why do they have this annoying habit? "All mosquitoes are generally attracted to the carbon dioxide we emit from our nose and mouth - replies the expert -. Therefore, especially when we are lying down, they tend to fly around our heads".

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Attracted to carbon dioxide

Some people claim that when there is even one mosquito, it bites them. Others, on the other hand, claim that they never get stung. "This depends a lot on the amount of carbon dioxide we emit, if we are sweaty, if we have done physical activity, if we are overweight, as well as on the lactic acid produced by our muscles, by the production of hormones and by the microbial fauna present on our skin Boni concludes. Who, speaking of repellents, specifies: "They are one of the most commonly used personal protective measures to prevent mosquito bites. They act by preventing contact with the insect and not by killing it, but the duration and effectiveness depends on many factors. The the most important thing to do is to prevent outbreaks, avoiding unknowingly breeding mosquitoes in our garden, vegetable garden, courtyard, terrace or basement, eliminating all stagnant water or situations that can lead to their formation following the rains. And when it is not possible to isolate the collected water, we should periodically treat it with special larvicidal products that are safe for human health and also for that of other animals".

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