If you want to keep mosquitoes away, certain essential oils might just do the trick – for a while anyway. New Mexico State University graduate student Hailey Luker’s research demonstrating the effectiveness of various essential oils as mosquito repellents was published recently in the journal “Nature.”

Luker’s paper titled “Repellent efficacy of 20 essential oils on Aedes aegypti mosquitoes and Ixodes scapularis ticks in contact-repellency assays” was published in the Scientific Reports section of the journal.

“There's an increasing consumer interest in more naturally derived repellants that repel mosquitoes and ticks,” Luker said. “That's mostly due to the negative connotation of synthetically derived chemicals. People feel that it’s less healthy for their bodies than natural essential oils. That brought in my interest in seeing if these essential oils work and how long they can repel for and avoid the annoying mosquito bites and reaction that you have to them, but you also want to protect yourself from diseases that mosquitoes and ticks transmit.”

Luker tested essential oils by making 10% essential oil and unscented lotion emulsions. Using human subjects Luker was able to test the repellency of these oils over time to determine which were most effective. Among the 20 essential oils she tested were cinnamon oil, clove oil and rosemary as well as commercial oils such as cedarwood, lemongrass and citronella.

“Hailey is an exceptional graduate student in my laboratory,” said NMSU Biology Professor Immo Hansen. “Her paper on the repellent efficacy of different essential oils is an important contribution to mosquito and tick repellent research.

“This is Hailey’s second first-author paper, the first one she published as an undergraduate researcher in my lab. It will not only be of interest to the experts in the field but also prove invaluable for people and companies that are trying to develop novel plant-based ‘green’ repellents.”

In a previous study, five essential oils displayed long-distance mosquito repellency using a Y-tube olfactometer (a procedure used to determine the behavioral responses of mosquitos towards or away from mosquito repellents and attractants).

Luker used an arm-in-cage method to measure complete protection time from mosquito bites. She used an Environmental Protection Agency-recommended procedure to measure the complete protection time from tick crossings. Of the 20 ingredients she tested in a 10% emulsion, clove oil, cinnamon oil, geraniol oil and 2-phenylmethyl propionate provided protection for more than one hour, while citronella and lemon grass lasted about half an hour.

Specific active ingredients from the EPA Minimum Risk Pesticides list can provide complete protection from mosquito bites and tick crossings for longer than one hour.

Luker’s previous research, published in 2022, focused on tick repellents. Her next challenge is improving the effectiveness of essential oils as a mosquito repellent.

“We're going to see if we can make a mixture of essential oils that can protect for at least three hours,” Luker said. “Our protection time is good for essential oils, but we would like to find a mixture that can protect people for longer. Especially if they're going outside, they're probably not going to want to recoat themselves every hour.”