In vitro effect of essential oils of three Lippia species on Moniliophthora roreri (Cif. and Par.) Evans et al., causative agent of moniliasis of cocoa (Theobroma cacao L.)

摘要

The in vitro antifungal effect of five essential oils (EOs) (EO1, EO2, EO3, EO4 and EO5) extracted from Lippia origanoides, L. citriodora and L. alba on isolates of Monilia (Moniliophthora roreri) was evaluated. Lippia plants were collected at five locations in Colombia, and monilia isolates were obtained from infected cocoa fruits collected in San Vicente de Chucurí, Santander, Colombia. The fungi strains (M1, M2, M3, M4 and M5) were characterized by morphology, germination and growth in culture media. Antifungal activity of different concentrations of EOs was evaluated against the M2 and the isolated strain of M. roreri (ATCC 64239) determining their effect on germination and mycelial growth inhibition. The five essential oils studied inhibited 100% germination and micelial growth when they were used at concentrations from 800 to 1000 µg/ml. Concentrations of 200 µg/ml also showed an effect on fungal isolates, being the EOs obtained from L. origanoides (EO2 and EO3) the most active. These were mainly composed of thymol, p-cymene, g-terpinene, timilo acetate, carvacrol, b-myrcene, trans- b-caryophyllene. Significant differences (P 0.05) on susceptibility were observed between the two fungal strains studied, being generally more susceptible the isolated M2 that the ATCC strain. The EOs of L. origanoides are candidates for use as biofungicides possible to control the moniliasis. Future studies oriented to determinate the in vivo antifungal activity of these EOs and its major components are required.