Chemical Composition and Insecticidal Activity of Essential Oil from Syzygium aromaticum (Myrtaceae) against the Sawtoothed Grain Beetle Oryzaephilus surinamensis (Coleoptera: Silvanidae)1

Abstract

Utilizing essential oils extracted from specific herbal plants offers an intriguing alternative to synthetic insecticides, which are known for their harmful effects on both consumers and the environment, in preventing the devastation caused by the sawtoothed grain beetle, Oryzaephilus surinamensis L. (Coleoptera: Silvanidae). This study aimed to explore the chemical composition and insecticidal activities of essential oil derived from Syzygium aromaticum (L.) Merrill & L.M. Perry against adults of O. surinamensis. The research involved assessing the chemical compound of the essential oil from the flower buds of S. aromaticum, evaluating its fumigant toxicity and its repellent effect on O. surinamensis adults through vapor-phase testing conducted in laboratory conditions at 30°C ± 5°C and relative humidity of 70% ± 5%. The experimental design used a completely randomized design with four replications and six concentrations (0, 10, 20, 30, 40, and 50 μl/l of air). A total of nine chemical constituents was identified, with eugenol (90.15%) emerging as the primary compound in S. aromaticum essential oil. The fumigation toxicity (50% lethal concentration) assessments on adult O. surinamensis at 24, 48, and 72 h revealed values of 9.70, 6.58, and 4.37 μl/l of air, respectively. Over the 24- to 120-h test period, the application of S. aromaticum essential oil at 50 μl/l of air resulted in the highest adult mortality among O. surinamensis. Notably, at a concentration of 40 μl/l of air, the essential oil of S. aromaticum demonstrated a fumigation efficiency of 90–100% at both 24 and 72 h, showing no significant difference compared with a concentration 50 μl/l of air. These findings highlight the potential of S. aromaticum essential oil as an effective insecticide for controlling O. surinamensis populations in agricultural storage.