"Catnip Repels Mosquitoes More Effectively Than DEET"
Catnip is a perennial herb belonging to the mint family and grows wild in most
parts of the United States, although it also is cultivated for commercial use.
Catnip is native to Europe and was introduced to this country in the late 18th
century. It is primarily known for the stimulating effect it has on cats,
although some people use the leaves in tea, as a meat tenderizer and even as a
folk treatment for fevers, colds, cramps and migraines.
There is no need to use it on the skin as it is a repellent .. it can be used effectively on clothing. If you use Fractionated Coconut as a carrier it is non-staining and will wash out of clothing easily. The Canadian Catnip essential oil is effective at a 5% dilution.
CHICAGO, August 27, 2001
Researchers report that nepetalactone, the essential oil in catnip that gives
the plant its characteristic odor, is about ten times more effective at
repelling mosquitoes than DEET the compound used in most commercial insect
repellents.
The finding was reported at the 222nd national meeting of the American Chemical
Society, the world's largest scientific society, by an Iowa State University
research group.
While they used so-called yellow fever mosquitoes (Aedes aegypti) one of several
species of mosquitoes found in the United States Peterson says catnip should
work against all types of mosquitoes.
The research led by Peterson put groups of 20 mosquitoes in a two-foot glass
tube, half of which was treated with nepetalactone. After 10 minutes, only an
average of 20 percent about four mosquitoes remained on the side of the tube
treated with a high dose (1.0 percent) of the oil. In the low-dose test (0.1
percent) with nepetalactone, an average of 25 percent or five mosquitoes stayed
on the treated side. The same tests with DEET (diethyl-m-toluamide) resulted in
approximately 40 percent to 45 percent with eight-nine mosquitoes remaining on
the treated side.
In the laboratory, repellency is measured on a scale ranging from +100 percent,
considered highly repellent, to -100 percent, considered a strong attractant. A
compound with a +100 percent repellency rating would repel all mosquitoes, while
-100 percent would attract them all. A rating of zero means half of the insects
would stay on the treated side and half on the untreated side. In Petersons
tests, catnip ranged from +49 percent to +59 percent at high doses, and +39
percent to +53 percent at low doses. By comparison, at the same doses, DEET's
repellency was only about +10 percent in this bioassay, he notes.
Peterson says nepetalactone is about 10 times more effective than DEET because
it takes about one-tenth as much nepetalactone as DEET to have the same effect.
Most commercial insect repellents contain about 5 percent to 25 percent DEET.
Presumably, much less catnip oil would be needed in a formulation to have the
same level of repellency as a DEET-based repellent.
Why catnip repels mosquitoes is still a mystery, says Peterson. It might simply
be acting as an irritant or they don't like the smell. But nobody really knows
why insect repellents work.
Chris Peterson, Ph.D., is a former post-doctoral research associate at Iowa
State University in Ames, Iowa, and is now a Research Entomologist with the U.S.
Department of Agriculture Forest Service, Wood Products Insect Research Service,
in Starkville, Miss.
Joel R. Coats, Ph.D., is professor of entomology and toxicology and Chair of the
Department of Entomology at Iowa State University in Ames, Iowa."
Note: This story has been adapted from a news release issued by American
Chemical Society for journalists and other members of the public. If you wish to
quote from any part of this story, please credit American Chemical Society as
the original source.
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