Better than DEET repellent compounds derived from coconut oil

Authors: Zhu, Junwei - Jerry; Cermak, Steven - Steve; Kenar, James - Jim; BREWER, GARY - University Of Nebraska; HAYNES, KENNETH - University Of Kentucky; BOXLER, DAVE - University Of Nebraska; BAKER, PAUL - University Of Nebraska; WANG, DESEN - Rutgers University; WANG, CHANGLU - Rutgers University; Li, Andrew; XUE, RUI-DE - Anastasia Mosquito Control District; SHEN, YUAN - Anastasia Mosquito Control District; WANG, FEI - Anastasia Mosquito Control District; Agramonte, Natasha; Bernier, Ulrich; FILHO, JAIRES - Federal University Of Big Dourados (UFGD); LIGIA, BORGES - Federal University Of Big Dourados (UFGD); Taylor, David; Friesen, Kristina

Submitted to: Nature Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/6/2018
Publication Date: 9/19/2018
Citation: Zhu, J.J., Cermak, S.C., Kenar, J.A., Brewer, G., Haynes, K., Boxler, D., Baker, P., Wang, D., Wang, C., Li, A.Y., Xue, R., Shen, Y., Wang, F., Agramonte, N.M., Bernier, U.R., Filho, J., Ligia, B., Taylor, D.B., Friesen, K.M. 2018. Better than DEET repellent compounds derived from coconut oil. Nature Scientific Reports. 8:14053. https://doi.org/10.1038/s41598-018-32373-7.
DOI: https://doi.org/10.1038/s41598-018-32373-7

Interpretive Summary: We report our discovery that naturally derived saturated medium-chain fatty acids from coconut oil function as repellent compounds. These fatty acids have broad repellency and long effectiveness against multiple blood-sucking insect species that feed on and often transmit diseases to humans and animals. Of the identified fatty acids from coconut oil, the medium-chain C8 to C12 fatty acids were found to be the dominant repellent compounds. In laboratory bioassays, two-week longevity in repellency against biting flies and bed bugs, and at least one week longevity against ticks was observed. In addition, strong repellency of coconut fatty acids was also found against mosquitoes, but only when relatively higher concentrations were topically applied. Repellency observed against these blood-sucking insects was stronger and longer than DEET. By encapsulating these fatty acids into an aqueous starch-based formulation, field trials showed this all natural formulation could provide over 96-hours of protection to cattle against biting flies, which is the longest from natural repellent products discovered.

Technical Abstract: Hematophagous arthropods are capable of transmitting human and animal pathogens worldwide. Vector-borne diseases account for 17% of all infectious diseases resulting in 700,000 human deaths annually. Repellents are a primary tool for reducing the impact of biting arthropods on humans and animals. N,N-Diethyl-meta-toluamide (DEET), the most effective and long-lasting repellent currently available commercially, has long been considered the gold standard in insect repellents, but with reported human health issues, particularly for infants and pregnant women. In the present study, we report fatty acids derived from coconut oil which are novel, inexpensive and highly efficacious repellant compounds. These coconut fatty acids are active against a broad array of blood-sucking arthropods including biting flies, ticks, bed bugs and mosquitoes. The medium-chain length fatty acids from C8:0 to C12:0 were found to exhibit the predominant repellent activity. In laboratory bioassays, these fatty acids repelled biting flies and bed bugs for two weeks after application, and ticks for one week. Repellency was stronger and with longer residual activity than that of DEET. In addition, repellency was also found against mosquitoes. An aqueous starch-based formulation containing natural coconut fatty acids was also prepared and shown to protect pastured cattle from biting flies up to 96-hours in the hot summer, which, to our knowledge, is the longest protection provided by a natural repellent product studied to date.