According to a new study released on Monday, American researchers have discovered several new potential insect repellants that are three times more potent than DEET, the active ingredient in most tick and insect repellents.

The study, conducted by Ulrich Bernier, a research chemist with the Mosquito and Fly Research Unit of the US Department of Agriculture (USDA) and his colleagues, was reported report in yesterday’s Proceedings of the National Academy of Sciences.

The researchers found that the new compounds protected human volunteers from mosquitoes two to three times longer than DEET, (n,n-diethyl-m-toluamide). They found that while DEET remained effective for less than three weeks, the new compound repelled mosquitoes for up to 10 weeks.

Ulrich Bernier said, "It would be good to have more effective repellents that protect against a greater number of insect species. I'm optimistic that we will have something come to the market that's better than DEET. These are the best candidates I have seen in the 15 years that I've been testing repellents."

The researchers found the most effective chemicals in a group of compounds related to the active ingredient in black pepper. In their lab tests the reseachers tested the compounds against the female Aedes aegypti, or yellow fever mosquito. They were now trying the compounds, known as N-acylpiperidines, against other types of mosquitoes.

After reviewing the new paper, Rudy Bueno, director of Mosquito Control for Harris County, said "This definitely sounds like promising work. This will have to be followed up by some pretty extensive field studies. But if the field data confirms the lab data, then you've got a potentially great product."