DNC News


Natural Insect Repellent:

Jacob Schor, ND
May, 2004


Subject:
A suggested natural insect repellent with links to website

Compared to other places I've lived in my life, Colorado does not have mosquitoes, at least not the sort of bugs that threaten to eat one alive.  After moving here I stopped carrying a bottle of DEET insect repellent in my backpack   This has changed though with the arrival of West Nile Virus (WNV).  It once was that a few mosquito bites were no big deal, part of summer, part of being outdoors.  With West ,Nile Virus rampant in the state, I'd prefer not to get bitten if I can help it.  But which is worse, West Nile Virus or the long term health risks from using insect repellents made with DEET?  I don't know if anyone knows yet. I'd prefer not to have to run the experiment on myself. Over the years we've tried various "Natural" insect repellents and found them either repulsive, ineffective or both.

I had the good fortune or meeting a most interesting fellow, John
Ellas, and his son, up on the Wapta Ice Field in Canada earlier this spring.  We began talking because he was using a handheld ultraviolet water sterilizer to purify their drinking water.   I discovered that he manufactures and sells a number of natural insect repellents. He impressed me and so did the thought that if a repellent would work against a full blooded Canadian Mosquito, Colorado mosquitoes wouldn't stand a chance.  He makes several different products, some which rely on a patented Swiss oil extract which is absorbed into the skin and produce an odor aura which mosquitoes don't like and others which rely on the unique aversion mosquitoes have to catnip oil.

Here are links to his website. You will discover that he has his hand in a number of other interesting business ventures.  We are going to order some of these products in the coming weeks and will be able to sell you them at the listed retail prices.

The repellents come in two strengths, regular and extra-strength.  Here is a description of the regular:
http://www.deetfree.ca/homs.cfm   


Here is a description of the extra strength formula:
http://www.deetfree.ca/xs.cfm


Here are some of the articles John has posted on his website describing the research on these products:
-New England Journal of Medicine [http://www.deetfree.ca/images/NEJM%20Comparative%20Analysis.pdf]  This article compares DEET against the natural repellents and finds most come up lacking staying power.  The one that came in second, what they refer to as "a soy bean based oil" is the patented Swiss base used in these formulas.  It doesn's last as long as the DEET, having only a 90 minute action compared to the hours and hours that strong DEET has, but it works...


-Johns Hopkins (pdf)  a short summary review of the NEJM article above.
-West Nile Virus and Biteblocker (pdf) [http://www.deetfree.ca/images/West%20Nile%20virus.pdf]


A nice review article about West Nile Virus, history, signs, symptoms and a mention of our Canadian product, referred to as BiteBlocker
-DEET (link about toxic encephalopathy) [http://www.deetfree.ca/images/West%20Nile%20virus.pdf]


 A news article arguing that DEET maybe more dangerous than West Nile

A news review on the research about catnip oil as a mosquito repellent:
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8/27/01

CATNIP DRIVES CATS WILD, BUT DRIVES MOSQUITOES AWAY

AMES, Iowa -- Although it drives cats wild, catnip appears to be a big turn-off for mosquitoes.

In research conducted at Iowa State University , catnip was 10 times more effective at repelling mosquitoes than the compound used in most commercial bug repellents. The finding was reported today at the 222nd national meeting of the American Chemical Society in Chicago .

Chris Peterson and Joel Coats studied the effect of nepetalactone on mosquitoes. Nepetalactone is an essential oil in catnip that gives the plant its odor. In past studies, the researchers had found that catnip oils could repel cockroaches. Peterson recently left a post-doctoral research position at Iowa State and is now working as an entomologist with the U.S. Forest Service in Starkville , Miss. Coats is the chair of ISU's Department of Entomology.

The researchers placed groups of 20 mosquitoes in a glass tube treated on one side with a high dose of nepetalactone. After 10 minutes, an average of 80 percent of the mosquitoes had moved to the untreated side of the tube. In a low-dose test, an average of 75 percent moved to the untreated side.

The researchers conducted similar tests with DEET (diethyl-meta-toluamide), the compound used in many commercial repellents. In those tests, 55 to 60 percent of the insects moved away from the treated side.

In the laboratory, repellency is measured on a scale from 100 percent (all mosquitoes repelled) to -100 percent (all mosquitoes attracted). In the ISU tests, catnip ratings ranged from 49 to 59 percent at high doses, and 39 to 53 percent at low doses.

Peterson said it took about a tenth as much nepetalactone to have the same repellency as DEET. "In other words, nepetalactone is about 10 times more effective than DEET," he said. "Most commercial insect repellents contain about 5 to 25 percent DEET. Presumably, much less catnip oil would be needed to achieve the same repellency as a DEET-based repellent."

Why catnip repels mosquitoes remains a mystery. "It might simply be an irritant," said Peterson, "or they just don't like the smell."

No animal or human tests are scheduled for nepetalactone, although Peterson is hopeful that will take place in the future. Iowa State has submitted a patent application for the use of catnip compounds as insect repellents. The project was funded by the Iowa Agriculture and Home Economics Experiment Station.

Catnip is a perennial herb in the mint family and grows wild in most parts of the United States . It also is cultivated for commercial use. It's primarily known for its stimulating effect on cats, although some people use the leaves in tea, as a meat tenderizer and as a folk treatment for fevers, colds, cramps and migraines. The plant also is used to make light yellow dye.



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