From: Mike Lorrey (mlorrey@datamann.com)
Date: Sun Jun 30 2002 - 10:37:06 MDT
Brian D Williams wrote:
>
> I take plenty of B complex, it seems to actually attract them. I
> was also wearing a good DEET repellent (Cutters, deep woods) it
> seemed to have little effect.
>
> The boys up on the roof had a constant group of about 50
> dragonflies picking them off for them, by the end of the 10 days we
> joked about getting dragonfly tatoos...
It seems that DEET allows 4% of mosquitos through to take a nibble, so
if you are surrounded by a thousand of the bugs, expect 40 bites or so.
It seems, though, that a natural perfect repellent has been found, a
chemical extracted from tomatoes:
http://www.discover.com/july_02/gthere.html?article=feat_tomato.html
Next summer, campers and picnickers may be turning to a tomato extract
to keep the mosquitoes from biting.
Michael Roe, an entomologist at North Carolina State University, was
designing synthetic insecticides when he realized their structures
resembled that of an oily organic compound that occurs naturally in
tomatoes. "I thought I would test the substance as an insect
repellent--on a whim, basically," he says.
Roe grabbed a cloth, dabbed it with a synthetic version of the tomato
molecule, and placed it in a cage full of cockroaches. They scattered.
He then did additional tests to show that the molecule repelled
mosquitoes and ticks as well.
Alan Brandt, president and chief operating officer of Insect
Biotechnology Inc., a Durham, North Carolina, company that develops and
markets insecticides, caught wind of this discovery while he was working
with Roe on several other projects. He decided to compare the tomato
compound to DEET, the most popular and effective commercial bug
repellent. Each year approximately one-third of Americans spray or
spread DEET-based insect repellents on their skin to keep bugs at bay.
A 20 percent solution of the tomato extract, applied to the arms of
volunteers, repelled mosquitoes as effectively as the same concentration
of DEET. But during a 12-hour test, DEET's efficacy slipped, letting 4
out of every 100 mosquitoes take a nibble.
Arms covered with the tomato-derived compound stayed bite-free. DEET
also has been linked to adverse reactions, including irritated skin,
rashes, and blisters. The Environmental Protection Agency considers DEET
to be safe when used correctly, but many parents worry about exposing
their children to the chemical. "People are looking for an alternative,"
says Brandt.
For proprietary reasons, Insect Biotechnology will not reveal the name
of the insect-repelling molecule. The company calls it IBI-246; IBI
stands for the company's name. Brandt says that while the compound is
well known and used in other products, he will not identify it until
after a patent for its use as a repellent has been granted.
Even to those in the know, IBI-246 is somewhat mysterious: Neither Roe
nor Brandt understands exactly how it deters mosquitoes from their blood
quest. Brandt suspects that, like DEET, the compound disrupts a chemical
receptor on the mosquito's antennae that the insect uses to guide itself
to its prey. Tomatoes probably create this molecule as part of the
plant's natural anti-insect arsenal, Roe says.
Because the tomato-derived substance is a naturally occurring compound
that is already used in other products, including cosmetics, it is known
to be safe and unlikely to produce any adverse skin reactions. Brandt
expects to have the tomato-inspired bug repellent on the market by the
time the mosquitoes start biting in 2003.
end quote.
For those into biochemistry, here's a challenge: identify the mysterious
compound based on the clues in this story.... frankly, since tomato
plants have been using this chemical for their own repelling of bugs,
I'm wondering at the gall necessary to attempt to patent it.....
Mike
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