Natural Coconut Fatty Acids Demonstrate Greater Efficacy Then Standard Insect Repellent

by | Jun 26, 2019 | 2018, Alternative Therapies, Fats and Oils - General

Written by Angeline A. De Leon, Staff Writer. The medium chain fatty acids, caprylic, capric and lauric, found in coconut oil exhibited significantly superior repellency than DEET against mosquitoes, biting flies, bed bugs, and ticks.

coconut oilBlood-sucking insects, including mosquitos, biting flies, ticks, and bed bugs, are notorious for their role in the spread of infectious diseases among both humans and animals 1-3. Viruses like West Nile, Zika, and African swine fever are attributed to biting arthropods 4, and while the use of repellents has proven effective for preventing disease transmission, many insect repellents are also associated with adverse health effects, especially in pregnant women and young children 5. DEET (N, N-Diethyl-meta-toluamide) represents the gold standard in insect repellents 6, providing almost 12 hours of protection against mosquitoes 7. However, due to growing evidence of the negative health effects associated with insecticides like DEET, researchers continue to investigate the efficacy of natural plant-based repellents as potential alternatives to conventional insect repellents 5. In a 2018 study 8 published by investigators at the U.S. Department of Agriculture, DEET was tested against medium-chain fatty acids derived from coconut oil, compounds which laboratory trials have shown to exhibit significant repellency against different types of flies 9, in a comparative trial of repellent efficacy.

Four different types of insect vectors were used in the present study: mosquitoes, ticks, biting flies, and bed bugs. Gas chromatography and mass spectrometry analyses were used to identify individual fatty acids contained in the coconut oil and their relative percentages. Laboratory bioassays were prepared for testing repellent efficacy of coconut fatty acids in each type of insect. This involved exposure of insects to individual coconut fatty acids at varying treatment dosages, and the calculation of respective repellency indices. Behavioral responses of bed bugs were also measured, and the repellent efficacy and longevity of a starch-based formulation containing composite coconut fatty acids was tested against biting flies in pasture cattle.

Analyses confirmed that coconut oil contained a series of medium chain fatty acids (e.g., caprylic acid, capric acid, linoleic acid, etc.), with lauric acid being the predominant fatty acid (accounting for 53% of total fatty acids). In biting flies, caprylic acid, capric acid, and lauric acid showed greater repellency than DEET, with over a 90% protection level at a dose of 1 mg/cm2 (p < 0.0001 for all). In bed bugs, coconut fatty acids were shown to have significantly stronger repellency than DEET one week after application (p < 0.05) and had stronger repellency than both DEET and a control repellent up to two weeks post-application (p < 0.001 for both). Coconut fatty acids also showed over 95% repellency in the lone star tick species and a repellency between 84% and 88% in the brown dog tick species for up to one week, both levels being significantly higher than those of DEET (p < 0.01). Coconut fatty acids performed comparably to DEET against mosquitoes, providing over 94% protection at a dose of 0.42 mg/ cm2, with lauric acid providing 73% protection at the same concentration. Finally, results showed that the starch-based preparation of composite coconut fatty acids was able to protect cattle against biting flies up to 96 hours post-application during field conditions in the summer season.

Findings from the present study show that natural fatty acids derived from coconut oil are not only effective as an insecticide, they are capable of outperforming the gold standard insect repellent, DEET, particularly in terms of longevity. While coconut oil itself was not found to have repellent properties, the medium chain fatty acids, caprylic acid, capric acid, and lauric acid contained in coconut oil exhibited greater repellency, relative to DEET, against biting flies, bed bugs, and ticks for a period of over a week. Notably, a laboratory formulation of a starch-based coconut fatty acid composite was associated with almost 100 hours of insect repellency, the longest known protection period afforded by a natural repellent agent to date. Thus, as a non-toxic, inexpensive, and relatively long-lasting and dynamic natural repellent, coconut oil is suggested to be a promising alternative to synthetic insecticides. Replication of current findings is warranted, as well as further examination of how the biochemical profile of individual fatty acids may relate to their repellency properties.

Source: Zhu JJ, Cermak SC, Kenar JA, et al. Better than DEET repellent compounds derived from coconut oil. Scientific Reports. 2018; 8: 14053. DOI: 10.1038/s41598-018-32373-7.

© The Author(s) 2018. This article is licensed under a Creative Commons Attribution 4.0 International License, http://creativecommons.org/licenses/by/4.0/.

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Posted June 26, 2019.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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