We have all faced the blood-sucking nuisance at some point, and in some cases are more deadly to humans than any other animal as their bites transmit malaria and other diseases that kill an estimated one million people around the world each year.
Traditionally, repellents have been used to prevent mosquito bites, but Ulrich Bernier, Ph.D, speaking at a symposium on biopesticides, explains that the most widely used repellent, DEET, whilst effective, is often overlooked due to its strong smell and feel.
Bernier and his team have been looking for better ways to combat mosquitoes which are user friendly and are suitable for use in cosmetics, lotions, and other products that currently incorporate mosquito repellents.
“We are exploring a different approach, with substances that impair the mosquito's sense of smell. If a mosquito can't sense that dinner is ready, there will be no buzzing, no landing and no bite,” he says.
Bernier states that a group of chemical compounds, including 1-methylpiperzine, block mosquitoes' sense of smell, and this may help explain why mosquitoes fly toward some people but not others.
A person's scent, Bernier explains, comes from hundreds of compounds on the skin, many emitted through sweat and others produced by bacteria.
To identify which of these attract mosquitoes, Bernier and colleagues used a special mosquito cage divided by a screen. They sprayed various substances into one side of the cage, and documented the effects in attracting mosquitoes.
Some compounds, like lactic acid -- a common component of human sweat -- were definite mosquito lures, drawing 90 percent of the mosquitoes to the screen. With other compounds, however, many of the mosquitoes didn't even take flight or seemed confused.
"If you put your hand in a cage of mosquitoes where we have released some of these inhibitors, almost all just sit on the back wall and don't even recognize that the hand is in there. We call that anosmia or hyposmia, the inability to sense smells or a reduced ability to sense smells," says Bernier.