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#Post#: 523--------------------------------------------------
Mosquito Attracting and Repelling Body Chemicals
By: AGelbert Date: December 8, 2013, 4:02 pm
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How Mosquitoes Are Drawn to Human Skin and Breath
Dec. 5, 2013 — Female mosquitoes, which can transmit deadly
diseases like malaria, dengue fever, West Nile virus and
filariasis, are attracted to us by smelling the carbon dioxide
we exhale, being capable of tracking us down even from a
distance. But once they get close to us, they often steer away
toward exposed areas such as ankles and feet, being drawn there
by skin odors.
Why does the mosquito change its track and fly towards skin? How
does it detect our skin? What are the odors from skin that it
detects? And can we block the mosquito skin odor sensors and
reduce attractiveness?
Recent research done by scientists at the University of
California, Riverside can now help address these questions. They
report on Dec. 5 in the journal Cell that the very receptors in
the mosquito's maxillary palp that detect carbon dioxide are
ones that detect skin odors as well, thus explaining why
mosquitoes are attracted to skin odor -- smelly socks, worn
clothes, bedding -- even in the absence of CO2.
"It was a real surprise when we found that the mosquito's CO2
receptor neuron, designated cpA, is an extremely sensitive
detector of several skin odorants as well, and is, in fact, far
more sensitive to some of these odor molecules as compared to
CO2," said Anandasankar Ray, an associate professor in the
Department of Entomology and the project's principal
investigator. "For many years we had primarily focused on the
complex antennae of mosquitoes for our search for human-skin
odor receptors, and ignored the simpler maxillary palp organs."
Until now, which mosquito olfactory neurons were required for
attraction to skin odor remained a mystery. The new finding --
that the CO2-sensitive olfactory neuron is also a sensitive
detector of human skin -- is critical not only for understanding
the basis of the mosquito's host attraction and host preference,
but also because it identifies this dual receptor of CO2 and
skin-odorants as a key target that could be useful to disrupt
host-seeking behavior and thus aid in the control of disease
transmission.
[img width=640
height=380]
HTML https://naturalunseenhazards.files.wordpress.com/2012/03/aedes-aegypti-mosquito54682.gif[/img]
Aedes aegypti
To test whether cpA activation by human odor is important for
attraction, the researchers devised a novel chemical-based
strategy to shut down the activity of cpA in Aedes aegypti, the
dengue-spreading mosquito. They then tested the mosquito's
behavior on human foot odor -- specifically, on a dish of foot
odor-laden beads placed in an experimental wind tunnel -- and
found the mosquito's attraction to the odor was greatly reduced.
Next, using a chemical computational method they developed, the
researchers screened nearly half a million compounds and
identified thousands of predicted ligands. They then
short-listed 138 compounds based on desirable characteristics
such as smell, safety, cost and whether these occurred
naturally. Several compounds either inhibited or activated cpA
neurons of which nearly 85 percent were already approved for use
as flavor, fragrance or cosmetic agents. Better still, several
were pleasant-smelling, such as minty, raspberry, chocolate,
etc., increasing their value for practical use in mosquito
control.
Confident that they were on the right track, the researchers
then zeroed in on two compounds: ethyl pyruvate, a
fruity-scented cpA inhibitor approved as a flavor agent in food;
and cyclopentanone, a minty-smelling cpA activator approved as a
flavor and fragrance agent. By inhibiting the cpA neuron, ethyl
pyruvate was found in their experiments to substantially reduce
the mosquito's attraction towards a human arm. By activating the
cpA neuron, cyclopentanone served as a powerful lure, like CO2,
attracting mosquitoes to a trap.
"Such compounds can play a significant role in the control of
mosquito-borne diseases and open up very realistic possibilities
of developing ways to use simple, natural, affordable and
pleasant odors to prevent mosquitoes from finding humans," Ray
said. "Odors that block this dual-receptor for CO2 and skin odor
can be used as a way to mask us from mosquitoes. On the other
hand, odors that can act as attractants can be used to lure
mosquitoes away from us into traps.
These potentially affordable 'mask' and 'pull' strategies could
be used in a complementary manner, offering an ideal solution
and much needed relief to people in Africa, Asia and South
America -- indeed wherever mosquito-borne diseases are endemic.
Further, these compounds could be developed into products that
protect not just one individual at a time but larger areas, and
need not have to be directly applied on the skin."
Currently, CO2 is the primary lure in mosquito traps. Generating
CO2 requires burning fuel, evaporating dry ice, releasing
compressed gas or fermentation of sugar -- all of which is
expensive, cumbersome, and impractical for use in developing
countries. Compounds identified in this study, like
cyclopentanone, offer a safe, affordable and convenient
alternative that can finally work with surveillance and control
traps.
Ray was joined in the study by the three UCR co-first authors
Genevieve M. Tauxe, Dyan MacWilliam and Sean Michael Boyle; and
Tom Guda. Boyle is now a postdoctoral researcher at Stanford
University.
[img width=640
height=380]
HTML https://naturalunseenhazards.files.wordpress.com/2012/03/aedes-aegypti-mosquito54682.gif[/img]
Aedes aegypti
The team tested the efficacy of ethyl pyruvate in the lab on
Aedes aegypti using an arm-in-cage set-up (the experimenter's
hand was gloved and not exposed to mosquito bites or the test
chemicals).
[img width=640
height=380]
HTML http://homepage.usask.ca/~vim458/virology/studpages2007/Yuri/culex.jpg[/img]
C. quinquefasciatus
The researchers tested the efficacy of cyclopentanone as a lure
on C. quinquefasciatus, the mosquito that spreads West Nile
virus and filariasis, using traps in a modified greenhouse at UC
Riverside.
Funding for the research was provided by the National Institute
of Allergy and Infectious Diseases (grants RO1A1087785 and
R56A1099778), the National Science Foundation, the University of
California Global Health Institute and the Bill and Melinda
Gates Foundation.
The UCR Office of Technology Commercialization has filed patents
for inventions reported in the research paper. Some pending
patents have been licensed to Olfactor Laboratories Inc. to
pursue further development and commercialization. ;)
HTML http://www.sciencedaily.com/releases/2013/12/131205141852.htm
#Post#: 1737--------------------------------------------------
Re: Mosquito Attracting and Repelling Body Chemicals
By: AGelbert Date: August 23, 2014, 11:46 pm
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Scientists Discover Why 1 in 5 People Attract Mosquitoes Like
Crazy‏ :o
[img width=640
height=380]
HTML http://www.createaforum.com/gallery/renewablerevolution/3-240814004029.png[/img]
[move]Mosquitoes Like OLD Sweat, Not Fresh Sweat :P[/move]
It was once believed that mosquitoes were attracted to human
sweat, but science has disproven that the sweat itself attracts
them. Instead, they are drawn by the chemical changes produced
by bacteria in your sweat.3, 4
Sweat itself is odorless until bacteria act upon it. Although
mosquitoes are not attracted to fresh sweat, if you offer them
up some "fermented sweat," they'll be all over you.[/I]
A 1999 study5 found that human sweat was attractive to malarial
mosquitoes after one to two days of incubation. During this
time, bacteria in the sweat multiplied, which changed its pH
from acidic to alkaline as sweat components decomposed into
ammonia.
They also found that malarial mosquitoes flock to foot odor
[img width=30
height=30]
HTML http://www.createaforum.com/gallery/renewablerevolution/3-300714025456.bmp[/img]<br
/>—they will even bite a pair of smelly socks if you hang them u
p
after wearing them for a few days.
Not only do mosquitoes find some odors irresistible, but others
have been found to impair their ability to find their hosts—and
some of these compounds are secreted by your body. One of these
compounds is [i]1-methylpiperzine, which blocks mosquitoes'
sense of smell so effectively that they are rendered oblivious
to the presence of a juicy human hand nearby.6 ;D
Insect sprays containing 1-methylpiperzine are in the works, but
thus far scientists have not been able to determine how to keep
the substance from evaporating off of your skin, as naturally
occurs over time.
Certain people seem to secrete more of these natural substances
than others, making them essentially invisible to mosquitoes,
which may help explain why some folks seem to be bitten more
than others.
Mosquitoes Plan Their Attack from Behind the 50-Yard-Line
Mosquitoes are attracted to a number of chemical compounds that
they can detect from an impressive 50 yards away. The males are
not interested in your blood, but the females are a different
story, thirsting after the protein and iron in your blood to
produce their eggs.
At this point in our scientific knowledge base, we know that
mosquitoes are attracted to the following:
Full article and video at link.
HTML http://articles.mercola.com/sites/articles/archive/2014/08/23/mosquito-repellent.aspx
HTML http://articles.mercola.com/sites/articles/archive/2014/08/23/mosquito-repellent.aspx
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