Adding a new weapon to the fight against insect-borne diseases such as Lyme disease and malaria, the Ministry of Environment on Monday approved a new chemical that repels and kills both chicks and mosquitoes.
The chemical, nut cotton, an oil found in cedar and grapefruit, is so safe that it is used by the food and perfume industries.
Nutcatone is considered toxic to humans and other mammals, birds, fish and bees, the EPA said in a statement.
Diseases caused by the bite of ticks, mosquitoes and meat have been displaced in the United States for the past 15 years, the Centers for Disease Control and Prevention said in a 2018 report. They include Lyme disease, anaplasmosis and Rocky Mountain spot fever of ticks; West Nile, dengue, Zika and chikungunya from mosquitoes; and pest from bats.
In tropical countries, malaria and yellow fever are major killers; elephantiasis is also spread by mosquitoes. Lethal Crimean-Congo hemorrhagic fever is spread by ticks, and kala azar is spread by sand flares.
Manuel F. Lluberas, a public health entomologist who has worked on mouse control campaigns around the world, said he hopes nutcat would be accepted by people who are afraid of synthetic repellents and that it could be made cheap to to be purchased through foreign aid programs such as the President’s Malaria Initiative.
The EPA registration only applies to nut cotton as an active ingredient, the statement said. Any formulations that use it in the future must be separately tested and registered.
The chemical kills mosquitoes, ticks, bedbugs and meat – and kills them, in high concentrations, according to the CDC It can also be effective against lice, sandbirds, midges and other pests, some of which can carry deadly diseases.
It is not oily, lasts for hours and has a pleasant grapefruit-like scent, said Ben Beard, deputy director of the division of vector-borne diseases at the CDC
“If you drank Fresca or Squirt, you drank nutcatons,” said Dr. Beard.
Nutcatone works differently from previous classes of insecticides and can kill bugs that are resistant to DDT, pyrethroids and other common insecticides.
Experts in insect diseases carried the news with cautious enthusiasm.
“Its use as an insecticidal soap has great potential,” said Duane J. Gubler, a former CDC chief of vector-borne diseases.
One proposed use exists in soups that allow people in showered areas to shower, repel and possibly kill ticks that try to attach to them.
Joel R. Coats, a specialist in insect toxicology at Iowa State University, said his laboratory has tested nutcatone and found it to be “an impressive repellent but a weak insecticide.”
It repels signs even better than synthetics like DEET, picaridin or IR3535 do, said Drs. Coats, and it is their likeness when repelling mosquitoes.
Unlike citronella, peppermint oil, lemongrass oil and other repellents based on vegetable oils, he added, nut cotton does not lose its strength after about an hour, but lasts as long as the synthetics.
But while it can also kill insects, he said, and that does so much of the chemical that it may not be practical.
“Most plant terpenes will kill bugs if you go for a high enough dose, but I have not seen any data supporting its use as an insecticide,” said Drs. Coats, and used a term for aromatic oils released by many plants invasive insects. “I’ve seen a lot of data on it as a repellent.”
Mikkel Vestergaard-Frandsen, owner of the company Vestergaard, which makes insecticide-impregnated nets to combat malaria, said he was interested in the composition, but wanted to know more about it.
Because babies sleep under the nets, every insecticide in their nest must be very safe.
In many areas, mosquitoes have developed resistance to the pyrethine-based insecticides now used in nets, which are synthetic versions of a chemical found in chrysanthemum flowers.
A version of nut cotton that can soak in netting for years should be developed, but good repellents usually dissolve too quickly before that, he said.
The CDC discovered the dehydrating properties of nutcatone nearly 25 years ago as part of a search for new tick-control compounds to combat Lyme disease, said Drs. Beard.
They researched cedar bark and chips “because there are all these folk tales that kill cedar insects – and people keep their clothes in cedar animals,” he said.
Cedar wood itself had very little effect on sign, he said, but Oregon State University scientists working with the bureau found the terpenic oil of Alaskan’s yellow cedar to be strongly absent. The Latin name of the tree is Cupressus nootkatensis, which comes from the people of Nuu-Chah-Nulth of Canada.
It is “not known in great detail” how nutcatone works, said Dr. Beard, but it seems to activate octopamine receptors, which in insects send electrical impulses from one nerve cell to the next. Unable to turn off the signal, the bugs tremble to death.
In mammals, adrenaline – which is chemically related to octopamine – performs the same function. But the compound does not trigger adrenaline receptors.
Later, the agency realized that the same chemicals, originally derived from grapefruit skins, were used as a flavoring and in perfumes.
The CDC licensed its patent to a Swiss company, Evolva, which chemically isolates fermenting yeast.
But doing the security studies needed for EPA registration was too expensive until the Zika epidemic of 2015-2016 came, said Drs. Beard.
That epidemic provided Congress with appropriate money for mouse control, and the CDC transferred part of it to BARDA, the Biomedical Advanced Research and Development Authority, which contracted with Evolva to complete the research.
Zika funding “was the key to moving the cow up the hill,” said Drs. Beard. But because nut cotton works well on both insects, he added, “it was not a bait-and-switch.”
