Bioactivity of the essential oil of an argentine collection of Acanthospermum hispidum (Asteraceae).

The essential oil of an Argentine collection of the annual herb Acanthospermum hispidum DC. (Asteraceae), which contains the sesquiterpenoids beta-caryophyllene (35.2%), alpha-bisabolol (11.4%), and germacrene D (11.1%) as major constituents, displayed molluscicidal effects on an adult population of Biomphalaria peregrina Orbigny (LD50 37.8 microg/mL) and produced alteration of the feeding and oviposition behavior of the polyphagous insect Spodoptera frugiperda Smith when incorporated in the larval diet at 250 microg/g. In addition, a selective antibacterial activity was observed against pathogenic strains of Staphylococcus aureus and Enterococcus faecalis (MICs 62.5 and 125 microg/mL), but was inactive at 125 microg/mL against three beneficial lactic acid bacteria. Synergistic interactions were further validated by FIC index determination of the combination of the antibiotics oxacillin and gentamicin and the essential oil on the four pathogenic strains evaluated.