What’s the News: Forget masking our scent or making us taste bad—sensory overload might be our most potent tool in repelling mosquitoes. And we might someday have a repellent for the job: Scientists have just discovered a molecule that zaps all of a mosquito’s odor receptors at once, overwhelming it. The molecule’s not ready to be deployed yet, but early tests indicate it could be thousands of times more effective than DEET. How the Heck:
In the human olfactory system, a scent molecule—whether it comes from a banana, gasoline, or chocolate cake—binds to a receptor that’s tailor-made for it, triggering a neurological cascade that results in you perceiving that specific smell. But in mosquitoes, there’s an extra step: after the scent molecule binds to its special receptor, that receptor must bind to another, more general receptor to broadcast its signal.
What the team found is a molecule that can jam that second class of receptors, making them broadcast constant scent static. Since mosquitoes rely heavily on smell to detect their hosts, this would have a catastrophic effect on their ability to feed.
What’s the Context:
The current gold standard for insect repellent is N,N-Diethyl-meta-toluamide, also known as DEET, the stuff in Off! and other popular sprays. For a long time it wasn’t clear how DEET functioned—you may recall some speculation about it masking CO2, which we emit and which mosquitoes smell well—but a study in 2010 indicated that it’s just that DEET tastes and smells bad to them (as well as to us).
Predictably, DEET’s not totally harmless: it’s not supposed to be applied under your clothing or on damaged skin or left on for longer than needed. Researchers have been trying to figure out an alternative repellent that could be used for containing malaria, and they've have noticed that mosquitoes get confused when bright lights or overwhelming smells hit them. This new molecule (called VUAA1) could help us use that to our advantage.
In a nice touch, this team approached the problem of interfering with mosquitoes’ sense of smell as if they were searching for a drug: they bombarded the receptors with more than 118,000 molecules from a “library” of compounds and found VUAA1 when they noticed its unusual effects.
The Future Holds: More tests to see how effective the molecule is at repelling mosquitoes, and more investigation of related compounds to see what can be mostly easily developed into a safe and effective repellent. Reference: Patrick L. Jones, Gregory M. Pask, David C. Rinker, Laurence J. Zwiebel. Functional agonism of insect odorant receptor ion channels. Proceedings of the National Academy of Sciences, 2011; DOI: 10.1073/pnas.1102425108
Image credit: poplinre/flickr
