Insecticidal, antimicrobial and antioxidant activities of essential oil from Lavandula latifolia L. and its deterrent effects on Euphoria leucographa

Abstract

Lavandula latifolia L. is a medicinal plant has fungicidal, antibacterial and antioxidant properties. The aim of this study was to determine the chemical composition, antioxidant and antimicrobial activities of essential oil (EO) of L. latifolia L. extracted by hydrodistillation method. A total of 22 constituents were identified in L. latifolia L. using Gas chromatography–mass spectrometry analysis. The compounds such as, gamma-terpinene (26.8 %), camphor (13.8 %), 1,8-cineole (10.2 %), lavandulol (9.3 %), terpinen-4-ol (9.1 %), linalool (8.9 %), b-elemene (3.2 %), b-pinene (3.1 %), 1,4-cineole (3.07 %), camphene (2.32 %), a-terpineol (2.3 %), and a-copaene (2.2 %) were determined. The antifungal activity of this EO against five phytopathogenic fungi revealed their broad-spectrum and strong antifungal properties. Notably, the EO showed potent activity on Trichophyton mentagrophytes (31 ± 1 mm) and the minimum inhibitory concentration value was 0.125 ± 0.05 μg/mL. The oil, analyzed for its DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS [2,2_-azinobis-(3-ethylbenzothiazoline-6- sulphonic acid)] free radical scavenging activity. Hydrodistilled EO had higher ABTS scavenging capacity than DPPH free radical scavenging power. Essential oil was used to test pesticide activity against Euphoria leucographa (Order: Coleoptera; Family: Scarabaeidae) infected in custard apple (Annona muricata) fruit. Results indicated that the spike lavender EO had contact toxicity on E. leucographa upon topical treatment. The effective concentration at 50 % (EC50) value of EC of L. latifolia L. was 0.37 % revealed considerable fumigant activity mainly due to the presence of fragrant compounds. Interestingly, custard apple (A. muricata) treated with EO effectively controlled the growth of T. mentagrophytes. Overall, antifungal and insecticidal properties of lavender EO, as a natural choice to preserve the harvested fruits thereby protecting the industrial crops.