Nothing keeps the mosquitoes away quite as well as DEET, but it's not the most innocuous of substances – besides stinking, it also melts plastic and synthetic fabrics, plus it's even been linked to problems in users' central nervous systems. It can also be prohibitively expensive for use in developing nations. Thanks to research being conducted at the University of California, Riverside, however, a new generation of non-toxic but highly-effective repellants may be on its way.
Previously, scientists had known that insects avoided DEET, but they didn't know which olfactory receptors the animals used to detect it. As a result, it was difficult to develop alternative repellants, as no one knew exactly what they should be targeting.
A UC Riverside team led by Prof. Anandasankar Ray, however, has located those receptors. They did so by examining genetically-engineered fruit flies, in which any neurons that were activated by DEET would fluoresce green. It turns out that the receptors are located on part of the antenna known as the sacculus.
Ray's team proceeded to test approximately 500,000 compounds, to see which ones activated those receptors. The compounds that worked were then narrowed down to ones that came from natural sources, then again to ones that worked well specifically on mosquitoes, and then again to ones that were already approved by the US Food and Drug Administration for use as food additives. Ultimately, that left three compounds –methyl N,N-dimethyl anthranilate (which is one compound, despite the comma), ethyl anthranilate and butyl anthranilate.
It is now hoped that one or more of these compounds – or others that are found to be safe, inexpensive and effective – could be used to keep nuisance insects away not only from humans and animals, but even from crops, too.
The university is currently looking into commercializing the technology. A paper on the research was published yesterday in the journal Nature.