July 2, 2012 - Michael Rodio - College of Science
Mosquitos are almost universally despised as despicable bloodsucking critters. But even though The Daily Domer has a pretty nasty allergy to mosquito bites, The Domer has to give the bugs some credit: Regardless of where The Domer is, the mosquitoes have an uncanny knack for being there too.
Zainulabeuddin Syed, a mosquito biologist with the University of Notre Dame’s Eck Institute for Global Health, has figured out how they do it, and it sounds like the tagline for a 1960's movie poster.
They can smell us.
Professor Syed (call him Zain) studies olfaction, or the sense of smell, in mosquitoes and other insects. Even though mosquitoes have relatively tiny brains, he says, they devote a lot of that little brain to smelling. Female mosquitoes, which feed on blood to produce their eggs, have extraordinary senses of smell.
ND Newswire writer William Gilroy, who covered the story on Syed's research, writes:
For example, Culex mosquitoes, which transmit West Nile and other life-threatening illnesses, are able to detect even minute concentrations of nonanal, a chemical substance given off by humans. They detect nonanal through receptor neurons on their antennae. Birds, which are the main hosts of mosquitoes, also give off nonanal. Birds are the main source of the West Nile virus, and when mosquitoes move on to feast on humans and other species, the mosquitoes transmit the virus to them.
Interestingly, Syed's research suggests that even though we might associate summer camp with ravenous swarms of bloodsucking mosquitoes, mosquitoes tend to focus on plants. Female mosquitoes feed on plant sugars for most of their energy, while male mosquitoes exclusively feed on plant sugars.
If Syed can understand the plants that mosquitoes like, then he can pioneer ways to control their populations. For example, Syed points out that DEET, the active ingredient in most bug repellants, is still the best chemical for the job because it has a strong smell to mosquitoes. But whereas prevailing ideas suggested DEET masked natural human scents, Syed and a team of researchers showed mosquitoes avoid DEET because to them, it smells revolting.
For people in developed nations, better mosquito control means more enjoyable summertime cookouts. But Syed's research for the Eck Institute for Global Health has a much bigger potential impact. In malaria-stricken parts of the world, where mosquito bites can mean death or at least serious sickness, mosquito control is a public health battle. In Africa alone, someone dies from malaria every 30 seconds - and that someone is usually a child.
So until we find a smell that repels mosquitoes as powerfully as mosquitoes repel us, DEET it is. But at least now we know why.
Contact Zainulabeuddin Syed via email for more on his research.