Evaluation of Anti-weevil and Fungicidal Activities of Oregano Essential Oil for Wheat Grains Postharvest Preservation

Medicinal plants have long been utilized in traditional herbal medicine and play a crucial role in preserving food grains during post-harvest storage. Modern research focuses on exploring the natural bioactive compounds of these plants to manage pests and safeguard grains during extended storage periods. In this study, the essential oil of Origanum compactum L. was extracted via hydrodistillation and its phytochemical composition was analyzed using gas chromatography-mass spectrometry (GC-MS). The insecticidal potential of this essential oil (EO) was evaluated against Sitophilus granarius (S. granarius) adult. GC-MS analysis identified carvacrol (53.79%) and thymol (16.55%) as the primary constituents. The EO exhibited significant repellent activity at concentrations as low as 75 µL mL-1, peaking at 150 µL mL-1. Strong fumigant activity was observed from the first day, achieving 95% mortality at 300 µL mL-1. Contact toxicity tests revealed dose-dependent insecticidal effects, with 100% mortality at 0.12 µL insect-1. Furthermore, grains treated with oregano EO showed a significant reduction in fungal contamination, decreasing from 4 × 108 spores g-1 in untreated grains to 3.7 × 104 spores g-1 with 0.6 µL g-1 of EO. These findings highlight the potential of this EO as a naturel and effective solution for protecting stored grains from pests and mold development.