Entomological Society of America
In a crowded marketplace of products advertised to repel
mosquitoes, consumers are wise to trust spray-on repellents containing DEET or
PMD, say researchers at New Mexico State University.
In a comparison study of
several mosquito-repellent products, "wearable" devices such as
bracelets or sonic repellers were found to be largely ineffective in repelling Aedes
aegypti mosquitoes.
"These findings are extremely important for consumers because they need to be aware that there are mosquito repellent products available that are ineffective," says Stacy Rodriguez, laboratory manager at the Molecular Vector Physiology Laboratory at NMSU. "While the labels of many products make strong claims, some products simply don't work."
The results of the study by Rodriguez and colleagues are soon to
be published in the Entomological Society of America's Journal of
Insect Science. They tested five wearable devices (OFF!® Clip-On, PIC®
Personal Sonic Mosquito Repeller, Mosquitavert® Repellent Bracelet,
Mosquito-No!™ Repellent Bracelet, and InvisabandTM), one candle (Cutter® Citro
Guard), and five sprays (Cutter® Lemon Eucalyptus, All Terrain® Kids Herbal
Armor™, Avon® Skin-So-Soft Bug Guard Plus Picaridin, Repel® Sportsmen Max
Formula®, and Ben's® Tick & Insect Repellent).
Each was worn by, used, or applied to a human subject in a wind
tunnel near a three compartment cage containing Ae. aegypti female mosquitoes.
Each repellent was tested for a 15-minute period, during which time mosquitoes
were free to wander from the middle compartment of the cage into either the
compartment closer to the human or the one further away.
Then, the mosquitoes
were counted in each compartment to determine how attracted they were -- or
weren't -- to the human wearing the repellent being tested.
The only wearable device that fared well in the study was OFF!®
Clip-On, which features a nebulizer to vaporize its repellent chemical,
Metofluthrin. The sonic repeller and bracelets showed no significant reduction
in mosquito attraction.
"Although the active ingredients in some bracelets may be
mosquito repellents, we hypothesize that the concentrations that are emitted by
all of the bracelets that we tested were too low to have an effect," the
researchers note in the study.
The five spray-on repellents tested showed significant, though
varying, levels of reduction in mosquito attraction in the test. Cutter® Lemon Eucalyptus
(30 percent oil of lemon eucalyptus, known by its chemical acronym, PMD) and
Ben's® Tick & Insect Repellent (98 percent DEET) were the most effective.
"This finding confirms the findings of several other studies that found
DEET and PMD the most effective and longest lasting mosquito repellents
currently available," the researchers write.
Rodriguez and her colleagues say consumers should seek out the
most effective repellents to avoid mosquito bites. "At a time where
vector-borne disease like Zika is a real threat, the most egregious danger to
the consumer is the false comfort that some repellents give them protection
against Ae. aegypti when they actually offer none," they write.