Are You Irresistible To Mosquitos? It Might Be Your Smell

There are times in large when someone complains of being bitten by mosquitoes while others appear to have escaped the feeding frenzy. You begin to wonder if something is wrong with you.

A new study finds that some people really are “mosquito magnets” and it probably has to do with the way they smell.

Mosquito “magnets” – people that appear to be bitten more than others – have intrigued scientists for many years. Theories, some with scientific origins and others are categorically known to be “old wives’ tales”, have proposed that a mosquito’s attraction could be based on several factors: blood type, sugar level, skin temperature, alcohol consumption, metabolism, etc.

The head of Rockefeller’s Laboratory of Neurogenetics and Behavior at Rockefeller University in New York; Professor Leslie Vosshall alongside some of his colleagues decided to investigate one of the leading theories behind mosquito snack preference: the odors produced by our skin – our natural “Eau de parfum”, if you will.

To put mosquito magnetism to the test, Vosshall and team recruited eight participants that were required to wear nylon stockings over their forearms for six hours a day for several days – admittedly not the trendiest fashion aesthetic.

The nylon stockings were then collected and Aedes Aegypti mosquitos were exposed to the stockings, which were matched up against each other until all pairs of stockings had been tested. The research team were blinded to which stockings had been worn by each of the participants.

The team discovered the mosquitos had a particular attraction to one set of stockings, “Subject 33” – they would swam towards them. “It would be obvious within a few seconds of starting the assay,” Dr. Maria Elena De Obaldia, a former postdoc in the Vosshall lab and co-author of the study, said. “It’s the type of thing that gets me really excited as a scientist. This is something real. This is not splitting hairs. This is a huge effect.”

Vosshall and colleagues ranked the stockings in order of most attractive to least attractive to the mosquitos. Subject 33 was 100 times more attractive to the mosquitos than stockings derived from another participants, Subject 19.

Using gas chromatography-quadrupole time of flight-mass spectrometry (GC-QTOF-MS), the scientists analyzed the sebum from the nylon stockings to explore what might explain the preferences at the molecular level. They found that participants classified as “mosquito magnets” produced carboxylic acids at a higher level than those that were less appealing to the mosquitos. Carboxylic acids are organic compounds that, in the skin, are utilized by bacteria to create our unique body odors.

To further substantiate their findings, the researchers enrolled an additional 56 participants to repeat their behavioral assay and sebum analysis. Again, Subject 33 was found to be the most appealing “parfum” for the mosquitos. “Some subjects were in the study for several years, and we saw that if they were a mosquito magnet, they remained a mosquito magnet,” said De Obaldia. “Many things could have changed about the subject or their behaviors over that time, but this was a very stable property of the person.”

Vosshall and colleagues wondered if their findings could be used to develop a strategy that decreases mosquito attraction. Mosquitos detect human odors via two sets of receptors: ionotropic receptors (IR) and Orco receptors. The researchers genetically altered the mosquitos in their study such that they were missing one or both of the receptors. To their dismay, they found that Orco mutants could still distinguish between “mosquito magnets” and those that had been deemed less attractive in the behavioral assay. IR mutants lost their attraction to a “varying degree” but could still locate the stockings.