Chemical composition and acaricidal activity of Arisaema anurans essential oil and its major constituents against Rhipicephalus microplus (Acari: Ixodidae)

This study aimed to determine the composition of essential oils from Arisaema anurans and to evaluate the acaricidal activity of the oil and its major components on the cattle tick Rhipicephalus microplus. The essential oil was characterized by high-level oxygenated terpenes and phenylpropanoids. Its major chemical compounds were found to be asarone (11.08%), cubenol (8.43%), guaiol (4.73%), eugenol (3.46%), linalool (3.41%), and alpha-bisabolol (3.29%). Adult immersion test revealed that the oil, asarone, and cubenol at 1.60% concentration presented oviposition reduction percentages of 36.3%, 44.2%, and 17.7%; hatching reductions percentages of 40.8%, 51.0%, and 35.1%; and final efficacy percentages of 65.0%, 73.2%, and 49.6%, respectively. Dose dependent egg hatching inhibition activities were exhibited by the oil, asarone, and cubenol, with LC50 values (in w/v) of 0.174%, 0.180%, and 0.381%, respectively. Larval immersion test further revealed considerable larvicidal activities against R. microplus of the oil, asarone, and cubenol, with LC50 values of 0.147%, 0.115%, and 0.338%, respectively. Biochemical assay of the homogenate of R. microplus revealed multiple mechanisms of acaricidal activity of A. anurans essential oil.