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 termites. The downside of catnip oil, Peterson said, is that it breaks down quickly in the environment. Termite-killing chemicals used commercially today remain effective for five years in government testing; catnip oil breaks down after a couple of weeks.
But that's not necessarily a barrier to eventual commercialization. Peterson hopes the essential ingredients in the oil might be able to be formulated to last longer, or the active ingredients modified. "Unfortunately you have a tradeoff, because you do need something that does last a long time, so there's greater potential for environmental damage," he said.
In its current form, catnip oil isn't something you can start using right away against termites in your own house. "Catnip oil has not been investigated for safety or efficacy, so I can't tell anyone to use catnip oil in their house to repel termites," Peterson noted, "and planting catnip around the outside of your house probably isn't going to do the job." The oil used in the experiments was extracted and concentrated.
"Hopefully it will be safe and effective, but that's just a hope for it at this point," he said.
While he was a graduate student at Iowa State University, Peterson investigated catnip oil for repelling cockroaches and mosquitoes and found that it works against both pests. But there's still the feline factor. "It would probably drive your cats nuts," he acknowledged.
The paper on this research, AGRO 61, will be presented at 3:05 p.m., Tuesday, March 25, at the Hampton Inn-Convention Center, Riverside I, during the symposium, "Environmental, Health, and Efficacy Aspects of Biologically Derived and Certified Organic Pesticides."
Chris Peterson, Ph.D., is a research entomologist with the Wood Products Insect Research Unit of the U.S. Department of Agriculture's Forest Service in Starkville, Miss.
Janice Ems-Wilson, Ph.D., teaches chemistry at Valencia Community College in Orlando, Fla.