Chemical composition of essential oils of different Siparuna guianensis chemotypes and their acaricidal activity against Rhipicephalus microplus (Acari: Ixodidae): influence of α-bisabolol

In the present study, chemical characterization of essential oils (EOs) from different chemotypes of Siparuna guianensis was performed and their acaricidal activity against Rhipicephalus microplus evaluated. Leaves of S. guianensis were collected from three municipalities of the Zona da Mata region, Minas Gerais State, Brazil: Sao Miguel do Anta (SMA), Tocantins (TO), and Vicosa (VI). The EOs chemical compositions were analysed using gas chromatography-mass spectrometry. To evaluate acaricidal activity, larval packet tests (LPT), and adult immersion tests (AID, were used. The major compound found in the SMA and TO samples was alpha-bisabolol (62.6 and 48.1%, respectively). In the VI sample, germacrene D was the predominant compound (25%). In the LPT, the highest concentration (20 mg/mL) of the VI sample caused a mortality rate of 81.1%, while for the TO and SMA samples, mortality was 100%. Pure alpha-bisabolol, acaused 100% mortality at a concentration of 10 mg/mL. The control percentage at the highest concentration (60 mg/mL) was 77.4, 87.8, and 98.6%, for the TO, SMA, and alpha-bisabolol samples, respectively. We demonstrate that there is variation in the chemical composition of the EOs of S. guianensis from different regions, and that the chemotypes rich in alpha-bisabolol presented greater activity against R. microplus.