Chemical composition and insecticidal activity of essential oil from fresh Callistemon viminalis leaves on Sitophilus zeamais, a pest of corn stocks

In a context where post-harvest losses of corn remain particularly high in West Africa, mainly due to the weevil Sitophilus zeamais, this study aims to explore plant-based alternatives to chemical insecticides. It evaluates the chemical composition and insecticidal efficacy of essential oils extracted from fresh leaves of Callistemon viminalis. Two extraction techniques were compared: hydrodistillation and steam distillation. The yields obtained, ranging from 1.39 to 1.59%, remain low due to the high-water content of the leaves.
GC-MS analysis reveals that hydrodistillation produces an oil composed mainly of oxygenated sesquiterpenes, notably nerolidol (50.64%) and viridiflorol (10.12%). Steam distillation, on the other hand, produces an oil richer in aromatic phenols such as eugenol (12.18%) and methyl eugenol (2.72%), as well as hydrocarbon sesquiterpenes. Biological tests show complete mortality of Sitophilus zeamais adults in less than 24 hours, regardless of the dose used or the extraction method. Statistical analyses indicate that only the time factor significantly influences insect mortality.
These results confirm the high insecticidal potential of Callistemon viminalis for post-harvest protection of cereals and suggest its value as a sustainable and environmentally friendly solution in Sahelian areas.