Abstract

The composition of the essential oil (EO) obtained by hydro distillation from dry leaves of Heliotropium stenophyllum (Heliotropiaceae) was analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The insecticidal activity of the oil against the house fly Musca domestica was evaluated and the dose necessary to kill 50% of flies (LC50) in 2 h was determined at 25 +/- 1 degrees C. The essential oil from Heliotropium stenophyllum showed potent insecticidal properties (LC50 = 1.09 mg/dm(3)) in comparison with other essential oils, in which at shorter times, the same bio-assay was used. According to GC and GC/MS analysis, junenol (19.08%); longiborneol (9.34%); (E, Z)-geranyl linalool (6.81%); selina-3,11-dien-6-alpha-ol (6.70%); alpha-cedrene epoxide (6.60%); heliofolen-12-al D (6.23%) and beta-epi-bisabolol (4.83%) were the principal components of the EO. The Heliotropium stenophyllum essential oil, made up exclusively of sesquiterpenes, showed a composition very different from the EOs of the other species of Heliotropium, studied, and present a great potential as a natural insecticide against houseflies.