Mosquitoes track down their blood meals by sniffing out human breath, skin, and sweat. But the main thing they zoom in on is the smell of carbon dioxide found in exhaled air. But what if we could mess with these bugs' sense of smell?
In a study published in the most recent issue of Nature, a team of scientists at UC Riverside did just that. They identified three groups of chemicals that disrupt the carbon dioxide receptors of some of the world's deadliest mosquitoes. One of those chemicals works by making the mosquitoes super-sniffers: they become so sensitive to smell that the bugs go crazy.
And that's just one way that scientists have discovered that they can thwart mosquitoes by altering their ability to smell. Researcher Anandasankar Ray and his colleagues did a series of tests to identify chemical odorants that have strong effects on the CO2-sensitive neurons that form the circuits in the mosquitoes' carbon dioxide-sensing machinery.
The team's findings have important implications in regions of the world where Anopheles gambiae, Culex quiquefasciatus, and Aedes aegypti – the three species of mosquito responsible for the spread of malaria, west nile virus, and dengue fever, respectively – infect an estimated half a billion people each year.
Each group of chemicals works a little differently to confound its target. The first actually mimics carbon dioxide, and could be used to lure mosquitoes away from their human targets and into insect traps; the second prevents the mosquitoes from detecting carbon dioxide altogether; and the third actually switches the CO2-sensing machinery of the mosquitoes into overdrive, overloading the mosquitoes' senses to the point of confusion.
The researcher's findings are promising on a number of fronts. For starters, they could herald the development of novel, more effective mosquito repellants that target the mosquito olfactory system. N,N-diethyl-m-toluamide, better known as DEET, is the archetypal olfactory-stumping repellant, but its high cost, the need for constant re-application to the skin, and its tendency to melt plastic (not to mention the fact that many mosquitoes have demonstrated resistance to DEET), are just a few of the things that underscore the importance of identifying new classes of repellant.
Speaking to the potential of chemicals like those described in the paper in the public health sector, Dr. Ray said:
The identification of such odour molecules, which can work even at low concentrations, and are therefore economical, could be enormously effective in compromising the ability of mosquitoes to seek humans, thus helping control the spread of mosquito-borne diseases.
You can read more about the researcher's findings, and reactions to the results from authorities in the fields of disease research and public health, at BBC News
Via James Gallagher for BBC News
Research Via Nature