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

Abstract

In the present study, chemical characterization of essential oils (EOs) from different chemotypesof Siparuna guianensis was performed and their acaricidal activity against Rhipicephalus microplusevaluated. Leaves of S. guianensis were collected from three municipalities of the Zona da Mataregion, Minas Gerais State, Brazil: São Miguel do Anta (SMA), Tocantins (TO), and Viçosa (VI). TheEOs chemical compositions were analysed using gas chromatography-mass spectrometry. Toevaluate acaricidal activity, larval packet tests (LPT), and adult immersion tests (AIT), were used.The major compound found in the SMA and TO samples was α-bisabolol (62.6 and 48.1%,respectively). In the VI sample, germacrene D was the predominant compound (25%). In theLPT, 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 α-bisabolol, acaused 100% mortalityat 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 α-bisabolol samples, respectively. We demon-strate that there is variation in the chemical composition of the EOs of S. guianensis fromdifferent regions, and that the chemotypes rich in α-bisabolol presented greater activity againstR. microplus.