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Date: July 1, 2003
Posted by: Suzanne Snedeker (sms31@cornell.edu)

The article mentions that  permethrin treated clothing is now being 
sold  to the general consumer. Does anyone have information on this?

S. Snedeker, Cornell Univ

[WestNileVirus-L Moderator's Note:
For more information about mosquito attractants and repellents, see 
the Environmental Risk Analysis Program's "West Nile Virus Resources 
for the General Public," Sections II "Insect Repellents" and Section 
III "Mosquito Biology and Control."
Find research articles using ERAP's  "West Nile Virus Bibliography of 
Scientific Literature," using the search term "Mosquito 
Repellents/Attractants."  These resources are one click away from 
ERAP's West Nile Virus homepage: 
http://environmentalrisk.cornell.edu/WNV/ (use the Navigation Bar on 
the right side of the webpage).
This topic has periodically been addressed on this listserv.  Access 
previous WestNileVirus-L postings from the listserv archives: 
http://environmentalrisk.cornell.edu/WNV/WNV-LArchiveIndex.cfm.   
-- Lois Levitan]


The New York Times
July 1, 2003
SEARCHING FOR WAYS TO COPE WITH BUZZ OF MOSQUITO SEASON

By JAMES GORMAN

It's the season of the whine - the high-pitched note that signals a 
prowling mosquito near your ear, and the even more annoying 
complaints emitted by humans wondering whether mosquitoes really 
should have a place in the web of life.

It's also the season of gadgets and sprays. The pressure to defeat 
the ubiquitous little bloodsuckers is greater than ever, since 
mosquitoes may carry West Nile virus or Eastern equine encephalitis, 
as well as cause the familiar red, itchy bumps. Also, mosquitoes 
breed in standing water, and at least in the Northeast, a wet spring 
is producing a bumper crop.

A vast arsenal is available for the mosquitophobe. A partial list 
includes Mosquito Deleto, the Electronic Swatter, Mosquito PowerTrap, 
Mosquito Terminator, Mosquito Magnet, the Bug Zapper, Mosquito 
Control Plus, the Solar Mosquito Guard, the Dragonfly Mosquito 
System, Mosquito 'Cognito, the Sonic Web and Insectivoro. Limited 
space makes it impractical to list every flowering of the American 
bug-killing imagination.

Apart from gadgets, there are citronella candles, sprays and lotions 
galore, synthetic and natural, and clothing impregnated with 
permethrin. For anyone with a taste for the primitive a full body 
coat of bear fat or axle grease will discourage both insects and 
unwanted suitors. So many choices: what's a poor bipedal blood meal 
to do?

Joseph Conlon has some thoughts on the matter. He is an ex-Navy 
entomologist who has solved numerous mosquito-related problems, like 
weaning the Marine Corps from Skin So Soft in the days before it 
added a new chemical repellent.

He is now the technical adviser to the American Mosquito Control 
Association and is more than willing to offer advice on mosquito 
defense. He favors simple, direct action, and is blunt about some of 
the devices sold widely. "Don't be taken in by a lot of newfangled 
gadgets," he said.

Instead, he says, you should first "know your enemy." For example, he 
says he gets calls from homeowners who say, "I've got these big 
mosquitoes that are bothering my kids." They're actually crane flies, 
he said, which look like giant mosquitoes but don't sting or bite.

Second, eliminate breeding sources. In other words, depending on the 
neighborhood you live in, either get rid of the old tires on your 
front lawn or make sure water isn't accumulating in your terra cotta 
garden ornaments. For ornamental pools, fish help, or there are 
chemicals that kill the larvae in water.

Fix your screens, make sure the bugs aren't getting in the house 
through air conditioners and consider the ultimate sacrifice: stay 
inside at dusk and early morning when the mosquitoes are most active. 
If you must go out to greet the dawn use insect repellents and wear 
loose-fitting clothing.

Mr. Conlon was not favorably disposed toward devices that use light 
to attract and electricity to fry insects. "These things are 
worthless," he said. "Actually they're worse than useless." They kill 
mostly larger, beneficial insects.

An often quoted study by Dr. Douglas W. Tallamy of the University of 
Delaware found that less than a quarter of a percent of insects 
killed by such a zapper were mosquitoes and at least 13 percent were 
beneficial insects. Zappers have undergone some changes, however, and 
some now use chemicals known to be effective at attracting mosquitoes.

Bats and purple martins are not much better than zappers, Mr. Conlon 
said. They do eat some mosquitoes, but prefer bigger juicier meals. 
Anti-mosquito plants are effective at keeping mosquitoes away from 
themselves, but they won't help you much, he said. And those sonic 
devices to repel mosquitoes? Tests had shown "no repellency 
whatsoever," Mr. Conlon said.

Dr. Tallamy concurred. He had not researched them himself, but said, 
"there's no physiological basis for them to work, and I've seen no 
evidence from any study that they work." Some frequencies of sound 
may, however, attract mosquitoes.

There are devices that clearly do lure and kill mosquitoes, although 
that doesn't mean they'll keep you from getting bitten. Among these 
are traps that use carbon dioxide and other chemicals to attract 
mosquitoes, which are then killed by various means, like being 
trapped until they die of dehydration. Carbon dioxide makes a 
mosquito think of the warm exhalations of a person relaxing with a 
book in a hammock, and they follow it. Other chemicals are known to 
attract them.

"The technology behind these and the theory behind these is really 
solid," Mr. Conlon said. But, how helpful they are in preventing 
bites depends on the situation. On isolated barrier islands they 
proved effective in reducing mosquito population. "In a subdivision 
they're not going to work as well," he said, because the neighborhood 
will provide a constant new supply.

Dr. Daniel L. Kline, a research entomologist at the Department of 
Agriculture Center for Medical, Agricultural and Veterinary 
Entomology in Gainesville, Fla., said the CO2 traps showed promise, 
but agreed that their effectiveness in the typical suburban yard was 
unknown. The question is how many mosquitoes you have. If you live 
near a salt marsh, using one trap would be like trying to empty the 
ocean with a cup.

Citronella coils and candles are weakly repellent, Mr. Conlon said, 
but a cloud of smoke from a smudge pot or a cigar will work, if 
you're willing to let it surround you.

Beyond clearing standing water, navigating the commercial minefield 
of mosquito gadgets, and staying inside, looms the prospect of 
protecting your person. Let's say you must venture into the yard, or 
perhaps you are planning to walk through a swamp in August, or you're 
a soldier and are being sent to an unpleasant location.

Again, Mr. Conlon does not mince words: "DEET is still king." DEET 
(N, N-diethyl-m-toluamide) is the active ingredient in most 
commercial insect repellents. A variety of other substances, natural 
and synthetic, have some repellent effect, but DEET, said Mr. Conlon, 
is so far the best. That doesn't mean, however, that you need high 
concentrations. A 25 to 35 percent concentration is best, he said, 
the higher concentrations don't provide much added benefit, but 
simply extend the time of effectiveness.

A report last year in The New England Journal of Medicine concluded 
that DEET was by far the most effective. The authors were Dr. Mark S. 
Fradin, a Chapel Hill, N.C., physician, and Dr. John F. Day, a 
medical entomologist at the Florida Medical Entomology Laboratory.

They reported that a 28 percent solution of DEET offered complete 
protection for about five hours. A "soybean-oil-based repellent" 
worked for about an hour and a half, a formula with a relatively new 
chemical repellent IR3535 for about 20 minutes, and all other 
botanical repellents for less than 20 minutes. "Repellent-impregnated 
wristbands offered no protection."

Avon, which has added the repellent IR3535 to its popular lotion, 
Skin So Soft, rejected the findings of the journal article, saying 
that laboratory studies are not as effective as field studies.

Although many consumers worry about health effects of insect 
repellents, the Environmental Protection Agency has declared normal 
use of DEET products to pose no significant risks for children or 
adults.

The American Academy of Pediatricians, a private group, takes 
positions on a variety of health issues that affect children, 
including the use of DEET. Its most recent advisory suggests that 
DEET is appropriate for use on children when there is a concern about 
insect-borne diseases, although children are much less likely than 
adults to become ill from West Nile virus.

The academy recommends 30 percent as a maximum concentration and 
suggests using the lowest concentration that will last for the time 
spent outdoors. Products with 10 percent are effective for about two 
hours.

The academy's advisory urges parents not to apply DEET more than once 
a day, also good advice for adults, and not to use a product that 
combines DEET with a sunscreen.

Some new products may be on the horizon. A new class of repellent, 
called SS-220, has been patented by scientists working for the 
Department of Agriculture and is now undergoing toxicity tests.

Dr. Kline's lab is investigating why mosquitoes find some people more 
attractive than others. There is definitely "scientific merit," he 
said, to the observations that one family member tends to draw 
mosquitoes.

Dr. Kline said a colleague at his lab, Dr. Ulrich Bernier, had 
patented several chemicals given off by unappetizing humans that seem 
to serve as masking chemicals or inhibitors. Any application of this 
research would be some way down the line.

A method of personal protection widely used in the military and now 
sold to consumers is clothing treated with permethrin, an effective 
insecticide that shouldn't be applied to the skin. With the clothing, 
you still need to apply a repellent to exposed skin. The Army has 
other good advice, which everyone should follow. Do not wear dog and 
cat flea collars, not even on your legs, no matter how bad the bugs 
are. A June bulletin on pest management from the Army warns against 
wearing flea and tick collars. "Animal flea and tick collars are NOT 
for human use!" the warning states.

The reason is simple. Dogs and cats don't sweat, but people do. And 
sweat can release some of the pesticides from the collars so they can 
be absorbed by the skin.

The precautions the military takes can also be grim. Mr. Conlon 
recalled that one problem he solved in his military career involved 
marine recruits at Parris Island, S.C., who were being eaten alive 
when they assembled at 5:30 a.m.

That, of course, was prime mosquito time. The solution was simple. 
Move the time up an hour, and have the recruits fall in at 4:30 a.m. 
After all, why should marines let some insects get a jump on them?

Copyright 2003 The New York Times Company | Home | Privacy Policy | 
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Full Story: http://www.nytimes.com/2003/07/01/health/01MOSQ.html?tntemail1

-- 
Suzanne M. Snedeker, Ph.D.
Associate Director of Translational Research
Sprecher Institute for Comparative Cancer Research
Cancer and the Environment
Breast Cancer and Environmental Risk Factors (BCERF) Program
www:  http://envirocancer.cornell.edu
Office location:  101A Rice Hall

Phone:  607 255-5943
Fax:     607 255-8207 or 607 254-4730
Email: sms31@cornell.edu
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