Comparative Study of the Insecticidal Activity of Essential Oils of Four Spontaneous and Cultivated Plants on Wheat Weevils (Sitophilus granarius L.)

Abstract

Synthetic insecticides are widely used to preserve foodstuffs; however, their extensive application poses significant risk to both human health and the environment. This underscores the urgent need for natural and less hazardous alternatives. In this context, the present study aimed to evaluate the insecticidal effect of essential oils extracted from four spontaneous and cultivated Moroccan aromatic plants against wheat weevils (Sitophilus granarius L.), a major pest of stored grains. The plants Origanum compactum, Origanum elongatum, Satureja calamintha, and Thymus zygis were collected from different regions in Morocco. The plants material both wild and cultivated were dried and pulverized. The essential oils from the dried powdered plants were extracted by hydrodistillation using a Clevenger-type apparatus. The adult wheat weevils (Sitophilus oryzae) were collected from storage facilities in the Taounate region of northern Morocco. The insects were treated with the essential oils at concentrations ranging from 0.1 to 1.0% for 24 hours. The essential oils demonstrated significant insecticidal effect, with all the oils achieving 100% mortality at 1% concentration within the first 24 hours of exposure. A comparative analysis of oils derived from the wild (spontaneous) and cultivated plants revealed variations in efficacy. Notably, essential oils from wild Thymus zygis achieved complete insect mortality in less than 24-hours. These findings underscore the potential of essential oils as effective tools for protecting stored foodstuffs. The findings also highlight the prospects for use of essential oils as bio-insecticides, offering a natural and environmentally friendly alternative for pest control.