BIOEFFICACY OF BOTANICAL ESSENTIAL OIL EXTRACTS ON Sitophilus oryzae L. (COLEOPTERA: CURCULIONIDAE)

Abstract

Sitophilus oryzae infestation in stored products causes significant economic losses, and the severity of these post-harvest impacts underscores the urgent need for sustainable, efficient, and affordable alternative insecticides for stored product protection. In response, the well documented disadvantages of commonly used synthetic pesticides have driven a growing shift towards botanical insecticides, particularly those formulated from essential oils, as promising eco-friendly alternatives. In this study, three plant extracts of essential oil, which were Allium sativum (garlic), Syzygium aromaticum (clove), and Cinnamomum verum (cinnamon), were tested for their repellency and mortality effect on S. oryzae. The repellency and mortality testing of S. oryzae against different essential oils was carried out in a petri dish where filter paper was treated with various concentrations of essential oil. Repellency results by the Sy. aromaticum showed the highest repellency, with the mean percentage of repellency between 56.57-74.33% as compared to C. verum and A. sativum. No significant differences (one-way ANOVA, P>0.05) between concentrations of 1-4µl/ml, indicating stability and no variation in repellency effect after exposure to Sy. aromaticum. Total mortality of S. oryzae was reached on day 4 for C. verum, which was faster than Sy. aromaticum and A. sativum that occurred on day 5 for all tested concentrations. Thus, these extracts were seen as a suitable alternative to replace chemical insecticides in controlling stored product insects due to their efficacy and safer options for food products.