Acaricidal activity of essential oils from Curcuma zedoaria and Alpinia zerumbet rhizomes against Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

Abstract

This study aimed to determine the chemical composition and evaluate the acaricidal activity of essential oils (EOs) from Curcuma zedoaria and Alpinia zerumbet rhizomes against Rhipicephalus microplus in vitro. EOs were obtained by hydrodistillation and chemical characterization was performed by gas chromatography coupled with mass spectrometry (GC-MS). The acaricidal activity of each EO was firstly evaluated on larvae by larval packet test at concentrations of 2.5, 5.0, 10.0, and 15.0 mg/mL. Through the result of the treatment on larvae, where only the EO from C. zedoaria caused mortality, it was realized the adult immersion tests at concentrations 10.0, 20.0, 40.0, 60.0, and 80.0 mg/mL for R. microplus engorged females. The GC-MS analysis of EOs showed 1,8-cineole (43.49%), curzerenone (13.40%) and camphor (12.29%) as major components in C. zedoaria, and 4-terpineol (22.27%), 1,8-cineole (16.51%), terpinene (10.75%), p-cymene (9.24%) and sabinene (9.18%) in A. zerumbet. Regarding the acaricidal activity, both in R. microplus larvae and engorged females, only the EO from C. zedoaria was effective, causing 100% larval mortality at a concentration of 15 mg/mL and 98.6% efficacy on engorged females at a concentration of 80 mg/mL. Thus, our results provide support for further investigation of C. zedoaria EO compounds as novel natural products to control R. microplus.