September 9, 2020;  Posted by: Mary Leigh Oliver

AUBURN UNIVERSITY, Ala. – The itchy, red whelps from mosquito bites are deeply familiar to most southerners. Alabama is home to approximately 60 different species of mosquitos. With the abundance of vegetation, water and warm weather in the state, mosquitos are able to breed and develop year-round. These factors make insect repellent an essential household item. While the potent, gaseous scent of most insect repellents is overbearing, the Environmental Protection Agency (EPA) recently approved a new chemical for use in mosquito and insect repellents. This chemical offers long lasting effects without the overbearing scent.


Nootkatone is the first chemical the EPA has approved for use in insect repellents in 11 years. Unlike most potent insect repellents, nootkatone smells like grapefruit and lasts for several hours. Nootkatone is an oil that comes from cedar trees, citrus fruits and vetiver grass. It was first identified in grapefruit peels and juice in the early 1960s. Ever since, it has provided a fruity, sweet and citrusy odor for use in foods, cosmetics and pharmaceuticals. Now its benefits stretch farther than simply enhancing smells and taste.

Xing Ping Hu, an Alabama Extension specialist of home grounds, garden and home pests, said within the past twenty years, numerous studies have taken place to explore nootkatone’s insecticidal activities including repelling, killing and anti-feeding.

“The Centers for Disease Control and Prevention (CDC) biologists focused their research on the repellency and killing power of nootkatone,” Hu said. “They found nootkatone to be an effective repellent and insecticide for use against ticks and mosquitoes, which spread Zika and other viruses.”

How It Works

Hu said nootkatone is an effective chemical for use not only against ticks and mosquitos, but other pests as well.

“Studies show that this grapefruit-scented perfume ingredient not only repels but also may kill mosquitoes, ticks, bedbugs, fleas, lice, weevils and other pests,” she said. “It also kills bugs that are resistant to DDT, pyrethroids and other common insecticides.”

According to Hu, researchers theorize that nootkatone’s mode of action is to stimulate insects’ nerve cell receptors involved in sending electrical impulses to cause fatal spasms, meaning the insects essentially twitch to death.  Since the nootkatone kills mosquitoes, it is much more effective in its prevention longevity than simply deterring the insect.

Because nootkatone is a volatile essential oil, it is environmentally friendly and nontoxic to humans and other mammals, birds, fish and bees.

“By giving their approval, the EPA is acknowledging that this chemical is safe and effective, formally giving the green light for companies to use nootkatone to develop new products for people and pets,” Hu said.

More Information

Hu says it is hoped that new nootkatone products will be available in the near future. In addition to nootkatone, there are eight other repellent chemicals, all of which the EPA registered 11 years ago.

  • Catnip oil
  • DEET
  • IR 3535
  • P-Methane-3, 8-diol (pmd)
  • Lemon eucalyptus oil
  • Picardin
  • 2-undecanone
  • Citronella oil

For more information on mosquitoes or other home pests, visit the Alabama Extension website or contact your county Extension office.

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As the Bibb County Coordinator for Alabama Extension, Matthew D. Hartzell coordinates the implementation of all Extension programs in Bibb County in many program areas. These program areas include 4-H and Youth Development, Animal Sciences, Food Safety and Quality, Forestry, Wildlife and Natural Resources, Human Nutrition, Diet and Health, Family and Child Development, Family Resource Management and Workforce Development, Commercial Horticulture, Home Grounds, Gardens and Home Pests, Farm and Agribusiness Management, and Community and Economic Development. Hartzell has served in his current position for 12 years and held primary program assignments in Community and Economic Development, Human Nutrition, Diet and Health, and Forestry Wildlife and Natural Resources.