Chemical composition and repellent potentials of two essential oils against larger grain borer, Prostephanus truncatus (Horn.) (Coleoptera: Bostrichidae)

Larger grain borer {Prostephanus truncatus (Horn.) (Coleoptera: Bostrichidae)} is a polyphagous pest which infests timber products, cereals, legumes, dried yam and cassava chips. Its infestation causes quantitative and qualitative losses, leading to food insecurity and reduced income generation for farmers. Essential oils (EOs) were obtained from fresh leaves of Cymbopogon citratus (DC.) Stapf and Lantana camara Linn. via hydrodistillation using Clevenger type apparatus. Each EO was assayed for repellent properties against P. truncatus using area preference methodology while pure acetone served as control. The percentage of oil yield from C. citratus and L. camara was 0.263% and 0.221% v/w, respectively. A total of 29 compounds were identified in C. citratus EO, dominated by oxygenated monoterpenes (92.58%), with citral (44.92%) and verbenol (34.97%) being the major compounds. A total of 47 compounds were identified in L. camara EO, dominated by sesquiterpenes hydrocarbons (49.96%), with gamma-cadinene (21.93%) and delta-cadinene, (+)- (9.88%) being the major compounds. When applied at 0.16 μL/cm2, L. camara exhibited a significantly (p