WASHINGTON, D.C. -- A chemical that resembles natural products from black pepper can deter mosquitoes four times longer than DEET, the world's most widely used bug repellent. The new substance could be used to protect people who live in the developing world, or to shield soldiers from insects when they deploy to countries with pest problems. "Our goal is to reduce disease transmission," said USDA synthetic chemist Maia Tsikolia, here at the American Chemical Society meeting. "It's very important for the American military, actually for mankind, to have effective repellents." The announcement of these potential new repellents comes on the heels of news earlier this month from a team of French researchers that reported DEET affects cells in a manner similar to nerve gas, and enhances the toxic effects of a common pesticide. The study was preliminary and was conducted on unprotected cells in petri dishes, so it may not be relevant for humans. But it became fodder for dozens of cautionary headlines leaving the public looking for alternatives.