Research outcomes present that salt-based mosquito management merchandise usually are not value their salt
reported in a new study published in the Journal of Medical Entomology. (Photo by Joseph Berger, Bugwood.org)
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A new study by a bevy of seasoned mosquito researchers offers consumers an important warning: products that claim to reduce mosquito populations with saltwater solutions are simply ineffective.
In a series of laboratory tests conducted at five sites on nine species of mosquitoes, the researchers found no evidence that adult mosquitoes are killed by salt ingested at concentrations used in several popular mosquito control products. The results will be presented in a new paper published today in the Journal of Medical Entomology.
Salt-based mosquito control products have caught the attention of researchers in recent years for boldly claiming that salt intake kills mosquitoes. The products often contain a combination of dried salt, sugar and yeast that is mixed with warm water by the shopper and then placed outdoors to attract mosquitoes, which then drink the liquid.
Donald Yee, Ph.D., BCE, professor at the University of Southern Mississippi’s School of Biological, Environmental and Earth Sciences, coordinated the study among nine researchers at multiple universities and public mosquito control agencies in the US and Australia. They used nine species of mosquitoes in their experiment, all from the genera Aedes, Anopheles, and Culex, which together are responsible for the vast majority of mosquito-borne diseases (such as malaria, dengue, yellow fever, and West Nile virus).
“There is a real public health threat from mosquito-borne diseases, and unfounded claims can have real ramifications for the health of people in mosquito-plagued areas,” says Yee.
Yee and colleagues conducted feeding experiments in which mosquitoes were offered one of four diets in cages: water only, salt water only, sugar water only, or a mixture of sugar and salt water. The concentrations in the diets – 1.03 percent salt and 8 percent sugar – were based on the product description of the most widely used salt-based mosquito control device on the market. The experiments lasted seven days, and the researchers recorded the number of dead mosquitoes every day.
Virtually no negative effects of salt intake on mosquitoes were observed in any of the studies. Mosquitoes fed sugar water with or without salt survived at high rates throughout the experiment, with few exceptions. Mosquitoes that were fed only water or only salt water fared worse, but with similar rates. Yee says the results were clear and compelling.
“The consistency of the results was somewhat surprising as nature is chaotic,” he says. “We would expect reactions to the diets we offer to be very different, but on the whole adding salt to regular water or sugar water did not result in increased mosquito death. Adult mosquitoes just don’t die any faster from drinking salt water. “
The results are consistent with a broad scientific understanding of mosquito biology. “Scientifically, it makes a lot of sense that mosquitoes should be able to handle low levels of salt, because all vertebrate blood contains a similar amount of salt,” says Yee. “If mosquitoes couldn’t handle salt, they would probably have evolved from feeding the blood millions of years ago.”
In fact, the leading salt-based mosquito control product uses a concentration of salt (1.03 percent) that is only slightly higher than that in human blood (0.9 percent).
The researchers say they want to provide consumers with the knowledge they need to spend their money wisely and protect their health. The use of mosquito control products with unsubstantiated claims can lead to a false sense of security. Instead, they recommend practices and products that have been repeatedly proven to reduce the risk of mosquito-borne disease: Draining stagnant water in yards (e.g. in bird baths, flower pots, tires, toys) to clear places, where mosquitoes can lay their animals’ eggs, treating stagnant water with insecticides that kill mosquito larvae, wearing long sleeves and pants outdoors, avoiding going outside when the mosquitoes are most active (dusk and dawn), and using Defense sprays containing DEET or other EPA approved chemicals.
Yee also recommends that members of the public contact their local mosquito control authorities for trusted advice. “Most mosquito control districts and mosquito control organizations have recommendations about what works and what doesn’t so you can avoid products with unsubstantiated claims,” he says. “As always, if it sounds too good to be true, it probably is.”