A smell from human skin attracts mosquitos that spread Zika, dengue, and yellow disease. The particular composition of the fragrance remained unknown up to this moment.
According to UC Riverside study, the fragrance that encourages a mosquito to locate and settle on its victim is formed by a combination of carbon dioxide and the chemicals 2-ketoglutaric and lactic acids. This chemical combination also encourages probing, or piercing mouthpieces to check for blood. This chemical combination appears to attract female Aedes aegypti mosquitos, which carry the Zika, chikungunya, dengue, and yellow fever viruses. Although this mosquito was found in Africa, it has subsequently migrated to many tropical and subtropical nations, including the United States.
In the journal Scientific Reports, the team’s new research finding and how it was made are described in detail. “Although others have discovered substances that attract mosquitoes, many of them don’t have a noticeable, immediate impact. This one does, according to entomologist Ring Carde of UCR.
Mosquitoes employ a number of indicators, such as carbon dioxide, sight, temperature, and humidity, to find their prey. Recent studies by Carde, however, indicate that skin scents are much more crucial for identifying a bite location.
We showed that mosquitoes land on visually unclear targets that are infused with these two scents, and these targets are not connected to heat or wetness, according to Carde. Skin odour is now the main determining factor.
Given the importance of smell in mosquitoes’ ability to successfully feed on humans, Carde set out to identify the precise compounds that give humans’ fragrance such power to the insects. Lactic acid, a component of the equation, was recognised as one of the chemical components of the odour cocktail as early as 1968.
Since then, numerous studies have found that human-produced compounds, such as ammonia and carbon dioxide, also draw these insects. Carde, who has spent 26 years studying mosquitoes, concluded that these additional compounds were not potent attractants.
Carde stated, “I had a sneaking suspicion there was some unexplored aspect to the chemistry of smells tempting the yellow fever mosquito. I sought to identify the precise combination.
The 2-ketoglutaric acid could not have been identified using the methods that chemists generally employ, according to Carde. Gas chromatography would not have detected this acid, which separates substances based on their polarity and molecular weight.
Because of the intricacy of the human odour profile and the minute levels of these compounds present in sweat, said scientist Jan Bello, previously of UCR and currently with insect pest control business Provivi, “I suspect that these molecules may not have been detected earlier.”
Carde turned to Bello, who was drawing substances from the sweat on his own foot to use as a mosquito attractant. He put glass beads in his socks and wore them for four hours while walking about to gather odours.
Bello remarked that wearing the beads was similar to “squeezing stress balls full of sand, but with your feet.” They would eventually become unpleasant after doing that for a while because they would get trapped in between your toes, which is the most aggravating aspect.
The expense was worthwhile despite the hassle. Bello purified compounds from the perspiration left on the sock beads and tracked how the chemicals affected the behaviour of mosquitoes. The combo that was the most active was thus revealed.
Future research is intended to ascertain whether the same substance works against other mosquito species and why different people are prone to be bitten differently. Some are more alluring to these mosquitoes than others, but no one has yet determined why, according to Carde.
Even while their discovery may not give information for the development of new repellents, the study team is confident that it may be used to attract, catch, and perhaps kill disease-carrying mosquitos.
Finally, we’re relieved that we identified these substances since we weren’t always sure we would. Thoughts don’t always come true, but we had a feeling they did, Carde added.