It used to be known that people whose skin contained more lactic acid were more likely to be attracted to small vampires. Flying insects also rate other chemicals for attractiveness, bacteria levels, and even body odor.
But in the newly published study, the researchers discovered how mosquitoes have evolved precise targeting mechanisms to differentiate between human and animal odors.
Carolyn McBride, an assistant professor of ecology and evolutionary biology and neuroscience, who is quoted in the report, explained the basis of the study: “We dive into the mosquito’s brain and ask: ‘ what can you smell what turns your brain on What makes your neurons work? And how does your brain react differently depending on whether you smell a human scent or an animal scent?“.
What have the scientists done?
The team of scientists used CRISPR-Cas9 to generate genetically modified Aedes aegypti mosquitoes, vectors of Zika virus, dengue virus, yellow fever virus and chikungunya virus.
These transgenic insects had brains that lit up when active, allowing experts to obtain high-resolution images of the brain. Later, these mosquitoes fed human- and animal-scented air through a wind tunnel to see what caught the insect’s attention.
The study highlights that human odor is made up of many different compounds, and that the same compounds are also present in most mammalian odors, albeit in different proportions, making it difficult to determine the exact proportions of the compounds.
To that end, the new research used the scent of 16 humans, two rats, two guinea pigs, two quail, one sheep and four dogs to stimulate the mosquito’s appetite.
Jessica Zung, author of the study, adds: For the human samples, we had a lot of great volunteers. We asked them not to bathe for a few days, then they undressed and put themselves in a Teflon bag.“.
” Why did the human volunteers have to be naked? The other fibers in the garment could falsify the data because they have an inherent odor.“.
Using the collected odors, the researchers developed a sophisticated system to infuse genetically engineered mosquitoes with odors into the brain area of the imaging device.
The study found that mosquitoes recognize two chemicals, decanal and undecanal, that are enriched with human odor and likely come from lipids in human skin rather than sweat.