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 Products with DEET or oil of lemon eucalyptus, which contains an
ingredient known as PMD, are more effective at repelling the Aedes
aegypti mosquito that carries Zika, chikungunya, yellow fever and
dengue, researchers found.
Wearable devices advertised as mosquito repellents should largely be
avoided, their data suggest.
With the recent outbreak of Zika virus, many mosquito repellents
became best-selling products, said Immo Hansen, of New Mexico State
University in Las Cruces, the senior member of the research team.
"They’re very popular," Hansen told Reuters Health, citing the
number of products for sale just on Amazon.com.
For the new study, researchers purchased and tested 11 products from
Amazon.com and local stores in New Mexico. Altogether they tested
five wearable devices, five sprays and one candle, using human
volunteers who hadn't bathed or used deodorant for at least 15 hours
before the experiments.
The tests were conducted in wind tunnels. Fifteen minutes after
releasing the mosquitoes, the research team counted how many bugs
had come close to the participant, to determine how many were
attracted to the person's smell.
Without any type of device or spray in the tunnel, about 89 to 91
percent of the mosquitoes were attracted to the volunteers,
depending on how far away they sat from where the insects were
released.
Of the five wearable devices, only one - the OFF! Clip-on -
significantly reduced the number of mosquitoes drawn to the
participants' scents. The attraction rate was only about 27 percent
when people were one meter from the cage. The device uses a fan to
disperse an insect-repelling chemical known as metofluthrin.
The other wearable devices included a speaker to repel mosquitoes
and three bracelets that emitted different oils.
"None of the bracelets had any effect on reducing attraction," said
lead author Stacy Rodriguez, who is also affiliated with New Mexico
State University.
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All of the spray-on repellents significantly reduced the number of
mosquitoes attracted to the participants, with attraction rates
varying from about 30 percent (with Cutter Lemon Eucalyptus and
Ben’s Tick & Insect Repellent) to about 79 percent. The tested
spray-ons generally used DEET or oils like lemon eucalyptus.
Like many of the wearable devices, the candle that contained
citronella oil did not significantly reduce the number of mosquitoes
attracted to participants' scents.
The products' popularity and their ineffectiveness suggests there
are not enough regulations in place to protect consumers, said
Hansen.
The researchers write in the Journal of Insect Science that
consumers may feel a false sense of comfort that they are protected
by these devices when they actually are not.
"I think (it's) definitely important to look at the active
ingredients before you purchase something," said Rodriguez.
The researchers caution that additional studies are needed since
they only used female Aedes aegypti mosquitoes.
SOURCE: http://bit.ly/2liHp1y Journal of Insect Science, online
February 16, 2017.
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