Insecticidal and Antifungal Activities of Chemically-Characterized Essential Oils from the Leaves of <i>Withania frutescens</i> L.

Abstract

The current study was conducted to investigate antifungal and insecticidal activities of essential oil extracted from the Moroccan Withania frutescens L. (EOW), and their chemical composition was profiled. To achieve this goal, EOW was extracted by the hydro-distillation method and their phytochemical constituents were characterized by gas chromatography-mass spectrometry analyses (GC-MS). Insecticidal activity was evaluated by use of four tests: contact toxicity, inhalation toxicity, and repellent tests. Antifungal activity was evaluated on Fusarium oxysporum f. sp. Ciceris (F. oxysporum) using different concentrations of EOW. GC/MS analysis revealed that EOW was rich in carvacrol (31.87%), thymol (30.08%), and camphor (9.13%). At a 1-µL/L dose, EOW exhibited mortality rates of 23.13 ± 1.07% and 24.41 ± 1.21% against Callosobruchus maculatus (C.maculatus) by inhalation and contact, respectively. Notably, EOW dose of 20 μL/L caused significant mortality rates of 95.1 ± 3.5% and 76.69 ± 1.71% by inhalation and contact, respectively. EOW exhibited an inhibitory effect on mycelial growth against the tested fungi F. oxysporum of 100% and 93.5 ± 1.1% for the 9 and 4.5 mg/mL doses, respectively. The reduced mycelial growth rate for F. oxysporum was recorded to be 0.3 ± 0.1 and 0.6 ± 0.1 mm/h for the EOW doses of 2.25 and 4.5 mg/mL, respectively. The outcome of the present work showed that EOW has a promising antifungal and insecticidal activity, and it can therefore be employed as a natural alternative insecticidal and mycocidal agent to replace the chemically-synthesized ones.

Keywords

• antifungal
• insecticidal
• <i>Withania frutescens</i> L.
• fungi
• <i>Fusarium oxysporum</i> f. sp. Ciceris
• <i>Callosobruchus maculatus</i>