Cinnamon oil kills mosquitoes more effectively than
DEET
Public
release date: 16-Jul-2004
American Chemical Society
Cinnamon oil
kills mosquitoes
NOTE FOR REPORTERS: The statement in our original news
release
(distributed 7-15) that cinnamon oil can "kill mosquito larvae more
effectively than
DEET" is misleading since we neglected to point out that
DEET is most
commonly used in insect repellants, not as a larvicide. We
apologize
for not making this clear. Please disregard the previous version
of this news
release and use the following version.
Cinnamon oil shows
promise as a great-smelling, environmentally
friendly pesticide, with the
ability to kill mosquito larvae, according to a new
study published in the
July 14 issue of the Journal of Agricultural and
Food Chemistry, a
peer-reviewed journal of the American Chemical Society,
the world�s largest
scientific society.
The researchers also expect that cinnamon oil could
be a good mosquito
repellant, though they have not yet tested it against
adult mosquitoes.
Besides being a summer nuisance, mosquitoes pose some
major public
health problems, carrying such deadly agents as malaria, yellow
fever and West
Nile virus. While conventional pesticide application is often
effective in
controlling mosquito larvae before they hatch, repeated use of
these
agents has raised serious environmental and health
concerns.
"These problems have highlighted the need for new strategies
for
mosquito larval control," says Peter Shang-Tzen Chang, a professor in
the School
of Forestry and Resource Conservation at National Taiwan
University and
lead author of the paper. Scientists are increasingly turning
to more benign
natural chemicals to ward off mosquitoes and other
pests.
Chang and his coworkers tested eleven compounds in cinnamon leaf
oil
for their ability to kill emerging larvae of the yellow fever mosquito,
Aedes aegypti. "Four compounds � cinnamaldehyde, cinnamyl acetate, eugenol
and anethole � exhibited the strongest activity against A. aegypti in 24
hours of testing," Chang says.
Larvicidal activity is judged with a
measurement called LC50. "The LC50
value is the concentration that kills 50
percent of mosquito larvae in
24 hours," Chang explains. Lower LC50
translates into higher activity,
because it takes a lower concentration to
kill larvae in the same amount of
time.
All four compounds had LC50
values of less than 50 parts per million
(ppm), with cinnamaldehyde showing
the strongest activity at an LC50 of 29
ppm.
Other common essential
oils, such as catnip, have shown similar promise
in fighting off mosquitoes,
but this is the first time researchers have
demonstrated cinnamon�s potential
as a safe and effective pesticide,
according to Chang.
Cinnamaldehyde
is the main constituent in cinnamon leaf oil and is used
worldwide as a food
additive and flavoring agent. A formulation using
the compound could be
sprayed just like a pesticide, but without the
potential for adverse health
effects � plus the added bonus of a pleasant smell.
Bark oil from the
Cinnamomum cassia tree is the most common source of
cinnamaldehyde, but the
tree used in this study � indigenous cinnamon,
or Cinnamomum osmophloeum �
has been of interest to researchers because
the constituents of its leaf oil
are similar to those of C. cassia bark
oil. The leaves of C. osmophloeum,
which grows in Taiwan�s natural hardwood
forests, could be a more economical
and sustainable source of cinnamon oil than
isolating it from bark, Chang
says.
Though the team only tested the oil against the yellow fever
mosquito,
cinnamon oil should prove similarly lethal to the larvae of other
mosquito species, the researchers say. In further studies they plan to test
cinnamon oil against other types of mosquitoes as well as different
commercial
pesticides.
"We think that cinnamon oil might also affect
adult mosquitoes by
acting as a repellant," Chang says. The researchers
haven�t yet tested this
theory, but they plan to find out in the near
future.
The Council of Agriculture of the Executive Yuan, a government
agency
in Taiwan, provided support for this research.
� Jason
Gorss
|