Repellent activity of the essential oil from Laurelia sempervirens (Ruiz & Pay.) Tul. (Monimiaceae) on Triatoma infestans (Klug) (Reduviidae)

Abstract

Triatoma infestans (Klug) is the principal vector of Chagas disease in Bolivia and neighboring countries. The objective of this study was to determine the chemical composition of the EO of the Chilean laurel, Laurelia sempervirens (Ruiz & Pay.) Tul. (Monimiaceae) and to evaluate its repellent effect on fifth-instar nymphs of T. infestans. The EO from L. sempervirens was obtained by hydrodistillation and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Their main components were cis-isosafrole (89.8%), beta-terpinene (3.9%), trans-ocimene (2.7%) and methyleugenol (2.2%). Repellency was evaluated on a circle of filter paper divided into two equal zones which were impregnated with test substances [EO or N,N-diethyl-3-methylbenzamide (DEET) as positive control] and acetone as blank control, respectively. Several concentrations of test substances between 4.125 and 132 mu g/cm(2) were tested. The EO from L. sempervirens produced significant repellency at concentrations equal or above 66.0 mu g/cm(2), while DEET repelled starting at 16.5 mu g/cm(2). Future works will be oriented to the study of repellent properties of cis-isosafrole alone and mixed with beta-terpinene, trans-ocimene and methyleugenol on T. infestans.