Biopesticidal activities of Lavandula pinnata essential oil against phytopathogenic fungi and a stored-product pest

Abstract

The growing resistance of agricultural pests to conventional synthetic pesticides calls for sustainable and eco-friendly alternatives. Lavandula pinnata L. (Lamiaceae), though known for its aromatic and medicinal properties, remains largely unexplored for biocontrol applications. This study aimed to evaluate the chemical composition and biopesticidal potential of L. pinnata essential oil (LPEO) against major fungal pathogens and insect pests. Essential oil was extracted from the aerial parts of L. pinnata by hydrodistillation and analyzed by gas chromatography–mass spectrometry (GC–MS). Antifungal activity was tested against four phytopathogenic fungi, namely, Penicillium digitatum (Pers.) Sacc., Phytophthora infestans (Mont.) de Bary, Aspergillus niger Tiegh., and Geotrichum candidum Link, using minimum inhibitory concentration (MIC) assays. Insecticidal efficacy was assessed against Callosobruchus maculatus through contact and fumigant bioassays, with mortality and reproductive inhibition evaluated after 96 h of exposure. Hydrodistillation yielded 0.45% (w/w) essential oil containing 27 identified compounds. GC–MS analysis revealed a phenolic monoterpene-rich chemotype dominated by carvacrol (24.91%), followed by p-cymene and γ-terpinene. LPEO exhibited potent antifungal activity, with MIC values ranging from 0.25 to 2% (v/v), and significant insecticidal efficacy against C. maculatus, with LC50 values as low as 1.95 µL/100 g seeds under contact exposure. At higher concentrations, the oil nearly abolished adult emergence, indicating strong ovicidal and repellent properties. Lavandula pinnata essential oil demonstrates broad-spectrum antifungal and insecticidal activities, suggesting its promising role as a natural, biodegradable biopesticide. Its efficacy, coupled with low persistence and safety potential, supports further in vivo and toxicological studies toward its integration into sustainable pest management programs.