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How do mosquitoes know that they are biting a human or an animal? Is it sweat that we give off a way to identify? A group of researchers from the Miami Tropical Genetics Laboratory has discovered an olfactory receptor in their antennae that could help them know if we are human enough to “bite.”
To understand it, we are going to think about specific mosquitoes, the Aedes aegypti, which are dangerous transmitters of Zika and dengue. Females find in the blood of vertebrates the nutrients needed to lay their eggs. They are attracted to the carbon dioxide that humans emit when they breathe and the lactic acids in their sweat. So they use the sense of smell to find their new prey. They get it due to an olfactory receptor called Ir8a, which is found in the antennae of mosquitoes and that serves to identify us about other animals.
Since the 60s it is known that mosquitoes were guided by sweat lactic acid to find us, but now they have managed to identify the gene that makes this union effective. If they managed to modify it, they could find the way that the mosquitoes of the future do not want to bite humans. This is explained to Sinc, the neurobiologist Matthew DeGennaro, leader of the work that has been published in the journal Current Biology: “When this gene is eliminated in the laboratory, the insect loses its ability to respond to volatile acids and, with it, approximately 50% of its attraction to humans.”
To achieve this, they eliminated the Ir8a from mosquitoes through a genetic editing system CRISPR-Cas9. Then they released wild mosquitoes and others with the modified gene near the arm of the researcher and found that the former did perch on him, while the latter did not feel any attraction for him in the 4 minutes of the experiment.
The researchers believe that thanks to these results, it will be possible to create much more effective repellents: “Smells that mask the Ir8a pathway could improve the effectiveness of current repellents. In this way, our discovery would help prevent people from being the main prey for these insects,” says DeGennaro.