Chemical composition and insecticidal activity of the essential oil of Pseudobrickellia brasiliensis (Spreng) R. M. King & H. Rob (Asteraceae) on Lutzomyia longipalpis (Diptera: Psychodidae)

Abstract

In Brazil, Leishmania infantum is transmitted mainly through the bite of the sand fly Lutzomyia longipalpis, the main visceral leishmaniasis (VL) vector. Although the most common vector control strategy is the application of synthetic insecticides, growing resistance to these products has sparked interest in developing new alternatives. In this context, plants emerge as a viable possibility due to the diversity of secondary metabolites with insecticidal potential. This work aimed to chemically characterize the essential oil of Pseudobrickellia brasiliensis and evaluate its toxicity on L. longipalpis. The essential oil was obtained by hydrodistillation in a Clevenger apparatus from fresh leaves of P. brasiliensis and chemically analyzed using gas chromatography coupled to mass spectrometry (GC-MS). For the bioassay, sand flies were collected in the field and then exposed to different concentrations of the essential oil (2.5, 5.0 and 10 mg mL⁻¹), also being used in the negative and positive control group. The mortality rate was assessed at established times. GC-MS analysis of essential oil of the P. brasiliensis identified 49 compounds with the predominance of monoterpenes, sesquiterpenes, and diterpenes. α-Pinene and isobicyclogermacrenal as the main constituents of the relative peak area of the total ion chromatogram with 17.9 and 13.3 %, respectively. The bioassay showed toxicity of P. brasiliensis essential oil on L. longipalpis at all concentrations evaluated, showing it to be a promising natural insecticide to be used in vector control of VL.