The oil derived from the catnip plant was found to repel and kill termites in a laboratory test. The researchers hope that eventually a commercial product derived from the oil might provide a less toxic alternative to pesticides used today.
Termites cause damages estimated at more than $1 billion annually in the United States. In New Orleans, the aggressive Formosan subterranean termite now found in at least 11 states is believed to infest about 30 percent of the area's live oak trees and costs home owners more than $300 million a year.
"One of the aims of looking at natural products is to find something that is less toxic to humans and less toxic to the environment as well," said Chris Peterson, Ph.D., a research entomologist with the U.S. Department of Agriculture.
Peterson, a researcher at the Wood Products Insect Research Unit of the USDA Forest Service in Starkville, Miss., and his coauthor, Janice Ems-Wilson, Ph.D., a chemist at Valencia Community College in Orlando, Fla., tested how well catnip-treated sand repelled termites.
The researchers treated sand with catnip oil, and to test vertical tunneling, put a two-inch barrier of treated sand in the middle of a test tube full of sand. Termites normally tunnel happily through sand-filled test tubes, but at high enough concentrations, the catnip oil stopped them. To test horizontal tunneling, the researchers put a catnip-infused barrier of sand in a pan, and then put termites on one side of the barrier to see if the termites tunneled to the other side.
A two-inch barrier of sand infused with catnip essential oil prevented termites from tunneling through it; at higher concentrations of oil, it killed the te