Mosquitoes are undeterred by salt-based solutions. Photo by Joseph Berger/Bugwood.org
Oct. 20 (UPI) -- Lab tests suggest a variety of popular salt-based mosquito-control products don't do what they claim -- kill mosquitoes.
In recent years, several salt-based products claiming to control mosquito populations have entered the market. The products typically feature a powder-like mixture of dried salt, sugar and yeast.
Users are instructed to mix the powder with water and place in a shallow dish outside. The bait is supposed to attract and kill mosquitoes upon ingestion.
For the study, published Tuesday in the Journal of Medical Entomology, an international team of researchers exposed nine different mosquito species to various salt-based solutions.
The nine species involved in the experiments, all hailing from the genera Aedes, Anopheles and Culex, are responsible for the majority of all mosquito-borne illnesses, including malaria, dengue, yellow fever and West Nile virus.
The caged mosquitoes were offered their choice of water only, salt water only, sugar water only or a sugar-and-salt water mixture based on the ingredients listed in various salt-based mosquito-control products.
Over the course of a week, researchers observed no adverse effects of salt-ingestion among the nine mosquito species.
"The consistency in the findings was a bit of a surprise given that nature is messy," lead study author Donald Yee said in a news release.
"We'd expect there to be a lot of variation in responses to the diets we offered, but, broadly speaking, adding salt to plain water or sugar water didn't lead to increased mosquito death. Adults mosquitoes just don't die faster because they drink salt water," said Yee, a professor of biological sciences at the University of Southern Mississippi.
Given that most of the blood that mosquitoes suck from humans and other mammals contains small concentrations of salt, it makes sense that the insects are able to withstand salt-based mosquito-control products.
Researchers suggest the best way to reduce mosquito populations is to reduce standing water -- forgo birdbaths and dump flower pots after it rains.
If homeowners decide to use insecticides, researchers suggest people wear long sleeves and protective gear during application.
And for people in the market for mosquito-control products, don't spend money on salt-based solutions.
"Most mosquito-control districts and mosquito-control organizations have recommendations for what does and what does not work, so you can avoid products with unsubstantiated claims," Yee said. "As always, if it sounds too good to be true, it probably is."