Study Finds Coconut Oil Compounds Repel Insects Better Than DEET

By Casey Kuhn
Published: Thursday, November 1, 2018 - 5:15pm
Updated: Friday, November 2, 2018 - 10:56am
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A federally funded study has found a pantry ingredient contains a naturally produced chemical that repels some insects better than DEET.

DEET is considered to be the most effective insect repellent on the market, used in bug sprays and to keep biting flies away from livestock.

Scientists with the U.S. Department of Agriculture-Agricultural Research Service now found specific coconut oil fatty acids have even stronger repellency, and they last a lot longer, too.

Four times longer, for bed bugs and ticks. The study said DEET stopped being effective after three days, while the compounds lasted for about two weeks.

USDA-ARS scientist Jerry Zhu led the study and said this is a big breakthrough.

“It’s kind of like a good surprise, and we actually have been working for so long just trying to find any safe repellent compound from the natural product sources," Zhu said. "Suddenly, we found after so many years of effort, we found out that this may be the one that can really benefit us a lot.”

For mosquitoes, the compounds work the same as DEET, but Zhu said it’s a good fit for pregnant women and young children looking for an effective DEET alternative.

Coconut oil itself is not a repellent. Instead, the fatty acids can be found in coconut oil and act as a repellent.

"The coconut oil contains a rich amount of fatty acids, but those fatty acids compound are connected with a sugar bond," Zhu said.

Zhu said the coconut oil industry is strong with a lot of research going on about it. That's how he knew those acids existed in the oil to begin with. 

"You have to actually hydrolyze the compound and make them a free fatty acid, and then it will work," Zhu said about the repellent effect. Hydrolyze means to break down a compound with water. When asked whether one could make the compounds at home with coconut oil, Zhu said the fatty acids themselves are cheap to buy.

Zhu said they studied the cost difference, too. The compounds are a much cheaper alternative to commercial repellents, with applications costing about 8 cents per cattle, versus 50 cents for the standard chemical, permethrin, used today.

USDA scientist Jerry Zhu said the idea to study these specific acids came from folk medicine in Southeast Asia. Many years ago, when there was no bug spray, people would burn plants to keep away pests.

“Because of the limitations, [there were] not other resources available to repel insects," Zhu said. "They burn a kind of grass and the smoke itself, actually, contains some of those acid compound.”

Zhu says they’re still working to figure out why exactly those compounds work to repel insects for so long. The USDA has filed a patent on the discovery to help sell it on the commercial market.

EDITOR'S NOTE: This story has been updated to clarify Jerry Zhu's title, what stage of patent filing the compounds are at, how long it lasts and what specific commercial product is used on livestock.

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