According to the conclusions of a study published in the journal Current Biology , Aedes aegypti mosquitoes use their smell to find people to bite and now we have identified the gene that allows mosquitoes to detect the smell of lactic acid present in sweating . One of the beneficial effects of this work is that it will facilitate the creation of more effective repellants to prevent the spread of infectious diseases transmitted in this way.
Thus, geneticists have found a sniffing protein molecule in mosquito antennae that, if clogged in some way, could confuse a bloodsucker or mosquito as to whether we are human enough to bite.
Aedes aegypti mosquitoes , which can spread Zika and dengue fever, prefer human blood to the blood of other animals. A series of experiments has shown that a protein called IR8a, found on the antennae of insects, is one of the molecules necessary to detect lactic acid, a component of human sweat.
“Human skin and its microbiome emit a lot of lactic acid compared to other vertebrates,” says geneticist Matthew DeGennaro, from Florida International University in Miami (USA).
Scientists have pondered since the 1960s that lactic acid could be one of the great clues to why aegypti mosquito bites target humans precisely.
IR8a’s role in detecting airborne acid traces was revealed in part by evidence of how mutant mosquitoes behave. Mutants with non-functional IR8a, but with their other abilities intact, were about half as likely to end up in a human arm or sweat-stained sock than normal mosquitoes, the researchers report.
Insects developed scent detection separately from vertebrates, and the six-legged version is “very complex,” says DeGennaro. Mosquitoes are based on three families of proteins that they smell and have overlapping abilities to identify groups of chemical compounds in the air. Proteins called ionotropic receptors, which include IR8a, target acids among other compounds. When a mosquito hunts, floating chemical signals combine with other information, such as atmospheric heat, humidity, and the sight of something palatable.
“ The key that Aedes aegypti mosquitoes can detect their human hosts lies in the olfactory receptor IR8a. When this gene is removed in the laboratory, the insect loses its ability to respond to volatile acids and, with it, approximately 50% of its attraction to humans ”, adds DeGennaro.
“The transmission of diseases such as dengue, yellow fever, Zika and malaria can be blocked if we prevent these mosquitoes from biting us,” says the expert. “But to do this, we first need to understand the molecular basis of mosquito behavior, ” he concludes.
Referencia: Raji et al.: “Aedes aegypti Mosquitoes Detect Acidic Volatiles Found in Human Odor Using the IR8a Pathway”. Current Biology. 28 de marzo de 2019
