Fleas, ticks and mosquitos have two things in common: they bite humans and they carry diseases. Fleas carry plague. Ticks carry Lyme disease, anaplasmosis and Rocky Mountain spotted fever. Mosquitos carry West Nile virus, malaria, dengue fever, Zika and chikungunya.
A 2018 Centers for Disease Control and Prevention (CDC) report found that in America, cases of insect-borne disease have tripled in the past 15 years.
The chemical nootkatone, recently approved by the U.S. Environmental Protection Agency (EPA), provides a new solution. Nootkatone, an oil found in cedar trees and grapefruits, repels and kills insect pests but doesn’t harm bees. The EPA claims it is nontoxic to humans, other mammals, birds and fish.
The CDC has known about Nootkatone for nearly 25 years but didn’t want to pursue costly EPA registration. Once the 2015-2016 Zika epidemic started, the need to control mosquito-borne disease became more urgent. Congress allocated money for mosquito control, the CDC passed some of the funds to the Biomedical Advanced Research and Development Authority (BARDA), and they contracted with Swiss company Evolva to complete the necessary EPA tests.
Nootkatone, a terpene oil originally isolated from Alaskan yellow cedar, smells like grapefruit. Even though Nootkatone is an oil, it does not feel oily on the skin and lasts for hours. It can be extracted from grapefruit rinds and even from fermenting yeast (as Evolva does). According to CDC Deputy Director Ben Beard, nootkatone is an ingredient in the soft drinks Fresca and Squirt.
The CDC claims the chemical can repel mosquitoes, ticks, bedbugs and fleas and may repel lice, sandflies and midges. In high concentrations, nootkatone can kill insects, including those resistant to DDT and pyrethroids. Beard says that nootkatone may work by activating receptors that send electrical impulses among nerve cells in insects. This can make the insects twitch to death. Humans don’t have these same kinds of receptors, so Nootkatone does not hurt them.
Public health entomologist Manuel F. Lluberas believes Nootkatone may be an acceptable substitute for synthetic repellents. He hopes that manufacturers will use it to create inexpensive products for use in the President’s Malaria Initiative (PMI) and other worldwide aid programs for insect-borne disease prevention and treatment.
U.S. President Bush began this initiative in 2005 by pledging a $1.2 billion increase (over 5 years) in U.S. funding of malaria programs in sub-Saharan Africa. The present PMI plan is to reduce worldwide malaria-related deaths by one third.
Iowa State University insect specialist Joel R. Coats said that in tests, nootkatone was “an impressive repellent but a weak insecticide.”
The ingredient is better at repelling ticks than DEET, picaridin and IR3535 and has about their same repelling ability against mosquitoes. Unlike other plant-oil repellents (citronella, peppermint oil and lemon grass oil), nootkatone stays active as long as common synthetic repellents do.
According to Coats, trying to use enough chemical to actually kill insects (as opposed to simply repelling them) would not be practical.
Nootkatone could be used in an insecticidal soap. Showering with such a soap could repel and even kill ticks in regions where they are a health threat.
Vestergaard owner Mikkel Vestergaard-Frandsen is looking into using nootkatone in the anti-mosquito nets his company makes to fight malaria. More research is needed to see if the repellent can last as long as needed in an insecticidal net.
Disclaimer: This article does not provide medical advice. Do not take action based solely on this article and always consult with an appropriate healthcare professional. This article is purely for informational purposes.