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ARS Home » Plains Area » Lincoln, Nebraska » Agroecosystem Management Research » Research » Publications at this Location » Publication #384990
Research Project: Management of Stable Flies to Improve Livestock Production

Location: Agroecosystem Management Research

Title: Repellent and acaricidal activity of coconut oil fatty acids and their derivative compounds against Amblyomma sculptum

Author
item BARROZO, MAYARA - Federal University Of Goias
item ZERINGÓTA, VIVIAN - Universidade Federal De Uberlândia
item BOREGES, LÍGIA - Federal University Of Goias
item MORAES, NÉLIO - Federal University Of Goias
item BENZ, KIM - Onederings
item FARR, AMY - Onederings
item Zhu, Junwei - Jerry

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2021
Publication Date: 10/12/2021
Citation: Barrozo, M.M., Zeringóta, V., Boreges, L.M., Moraes, N., Benz, K., Farr, A., Zhu, J.J. 2021. Repellent and acaricidal activity of coconut oil fatty acids and their derivative compounds against Amblyomma sculptum. Veterinary Parasitology. https://doi.org/10.1016/j.vetpar.2021.109591.
DOI: https://doi.org/10.1016/j.vetpar.2021.109591

Interpretive Summary: Amblyomma sculptum has a large veterinary and public health importance in Brazil due to its direct and indirect damages to domestic animals, wildlife and humans. This tick is also the main vector of Rickettsia rickettsii bacterium, the etiological agent of Brazilian spotted fever, which is recognized for its high lethality in humans. The most common control method for A. sculptum on animals is relied on the use of chemical acaricides. Although effective, frequent and over-dosed applications can lead to a fast development of resistant strains build-up, as well as environmental concerns and animal toxicity. Medium chain fatty acids, which are the main constituent compounds of coconut oil, were found to repel hematophagous arthropods such as stable flies (Stomoxys calcitrans), horn flies (Haematobia irritans), bedbugs (Cimex letularius), mosquitoes (Aedes aegypti) and ticks (Amblyomma americanum and Rhipicephalus sanguineus sensu lato). In the present study, the repellent and acaricidal activities of various formulations of coconut oil fatty acids, their derivatives and catnip oil were evaluated against nymphs and larvae of A. sculptum.

Technical Abstract: This study was carried out aiming to evaluate the repellent and acaricidal activity of coconut oil fatty acids including their methyl ester derivatives and catnip oil against nymphs and larvae of Amblyomma sculptum. Repellent candidates, coconut oil fatty acids (coconut FFA mainly C12, C10 and C8 acid); lauric acid (C12 acid); capric acid (C10 acid); methyl laurate; methyl caprate and 10% each of C12, C10 and C8 acid (1:1:1) in lavender oil formulation (CFA in lavender formula) and catnip oil (Nepeta cataria), were screened using a Petri dish bioassay to assess repellency. Catnip oil, methyl caprate, methyl laurate, and CFA in lavender formulation repelled ticks strongly (P'0.05) at almost all times evaluated, with an average of 77.8 to 100% repellency. Some candidate repellents with consistent strong repellence observed were selected for further evaluation, with coconut CFA in lavender formula showing a repellency lasted up to 7 days, while those of catnip oil and methyl caprate were active for 4 and 3 days, respectively. For the acaricide test, five concentrations (2.5; 5; 10; 15 and 20 mg/mL) were evaluated using the larval packet test. Only CFA in lavender formula and two methyl esters showed acaricidal activity, with methyl laurate presenting the strongest toxicity at 15 mg/mL concentration, which was effective against more than 93% of the tested larvae. Catnip oil caused no mortality of A. scultptum larvae in all concentrations tested.