Acaricidal potential and phytochemical evaluation of Spilanthes acmella flower for the control of Asian blue tick, Rhipicephalus (Boophilus) microplus

The aim of this study was to evaluate the acaricidal potential of petroleum ether, hexane and methanol extracts of Spilanthes acmella flower against the cattle tick, Rhipicephalus (Boophilus) microplus. The extracts were made through soxhlet's extraction method. Methanol extract was found more efficacious than the other ones. By partitioned chromatography of methanolic extract, four fractions were isolated: hexane, ethyl acetate, chloroform and aqueous. Chloroform fraction (F III) exhibit highest acaricidal potential with LC₅₀ value 129.42 ppm with 210.30 ppm upper fiducial limits and 48.55 ppm lower fiducial limits and LC₉₀ value 762.49 ppm with 1332.87 upper and 192.10 ppm lower fiducial limits against R. microplus. GC-MS analysis of fraction III demonstrated that the compound N-Isobutyle-2(E), 6(Z), 8E decatrienamide covers the highest area (70.83) % with retention time 28.847 which may be responsible for acaricidal activity.