Acaricidal Activities of The Essential Oils of Six Ethnoveterinary Plants Used by Fulani Herdsmen in Nigeria

Ticks and tick-borne diseases cause devastating effects on livestock production. The misuse of synthetic acaricides in tick control causes increasing levels of acaricide resistance, environmental pollution and livestock byproducts residue accumulation. In the search for an effective and safer alternative, this study evaluated the acaricidal efficacies of essential oils (EOs) of six documented ethnoveterinary plants. The EOs were extracted by hydrodistillation, and acaricidal efficacies of six different concentrations of each plant were tested using adult immersion test. Amitraz and cypermethrin, and 2% dimethylsulphoxide served as positive and negative controls, respectively. Data was analyzed by the probit method, and lethal concentrations were determined using regression analysis. A p value <= 0.05 was considered significant. Cymbopogon citratus, Hyptis suaveolens and Ocimum gratissimum EOs (20, 10, 5%) produced 100% tick mortality while Eucalyptus globulus EO exhibited 100% mortality only at 20% concentration. The mortalities from Balanites aegyptiaca and Citrus limon EOs at 20% concentration were 90 and 47.5%, respectively. Lower concentrations caused tick mortalities of less than 50%. Cymbopogon citratus/E. globulus EO combination showed the highest synergistic acaricidal activity (LC50- 0.63%; 100% inhibition of tick oviposition and hatchability). Cymbopogon citratus EO may be developed into an effective and eco-friendly botanical-based acaricide, and studies are ongoing to determine its safety profile/mechanism of action.