Thaindian News

Washington, Aug 17 (IANS) After more than 50 years of research, scientists have finally discovered a number of new mosquito repellants that keep the dangerous pests away much longer than before.
The new repellants beat DEET, the current gold standard for warding off mosquitoes. DEET is N,N-Diethyl-meta-toluamide, a slightly yellow oil. It is the most common active ingredient in insect repellants.

The new repellants make mosquitoes stay away three times longer than DEET, and without the latter’s odour. Nor does it cause DEET’s sticky-skin sensation.

But there’s a fly in the ointment: The odds may be stacked against any of the new repellants finding a place on store shelves this year or next — or ever.

Ulrich Bernier from the Centre for Medical, Agricultural, and Veterinary Entomology (CMAVE), who led a new study on the subject, said the costly, time-consuming pre-market testing and approval process is a hurdle that will delay availability of the repellants, which were developed last year.

Bernier and his team developed the repellants with what they say is the first successful application of a computer model using the molecular structures of more than 30,000 chemical compounds tested as repellants over the last 60 years.

Using 11 known compounds, they synthesised 23 new ones. Of those, 10 gave about 40 days protection, compared to 17.5 days for DEET, when a soaked cloth was worn by a human volunteer. When applied to the skin, however, DEET lasts about five hours.

“If the mosquitoes don’t even land, we know the repellent is surely working,” he explained. “If they walk around on the cloth-covered-arm, they are on the verge of being repelled. If they bite… on to the next repellent,” Bernier said, according to a CMAVE release.

These results were presented Monday at the 238th National Meeting of the American Chemical Society (ACS).