Composition and insecticidal activity of essential oil from Ruta graveolens, Mentha pulegium and Ocimum basilicum against Ectomyelois ceratoniae Zeller and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The aim of this research was to explore the chemical composition and evaluate the insecticidal activities of Ruta graveolens, Mentha pulegium and Ocimum basilicum leaves essential oils from south of Tunisia. Fumigant toxicities were assessed toward the most important and destructive insects attacking dates in storage in Tunisia namely Ectomyelois ceratoniae and Ephestia kuehniella. GC–MS analyses showed that major compounds of O. basilicum essential oil were linalool (29.23%), methyl cinnamate (18.97%) and eugenol (5.84%), followed by 1,8-cineole (5.74%), α-cadinol (5.69%), estragol (4.72%) and α-bergamotene (4.24%), whereas M. pulegium essential oil had 1,8-cineole (14.60%), p-menthan-3-one (14.9%), piperitenone (11.4%), carene (10.19%), menthol (8.76%), trans-caryophyllene (6.64%) and menthyl alcohol (6.14%) as major components. The essential oil extracted from R. graveolens was remarkably rich in hydrocarbon ketones (52.5%) mainly 1-nonene (19.4%), 2-undecanone (16.22%) and 2-nonanone (11.9%). Results demonstrated that fumigant toxicity varied with insect species, essential oil concentration and exposure time. Lethal concentration (LC₅₀) values of O. basilicum, M. pulegium and R. graveolens were, respectively, 0.96, 0.3 and 1.02 µL/L air on E. kuehniella and were 1.23, 0.31 and 1.97 µL/L air on E. ceratoniae. M. pulegium essential oil was more toxic to the two stored date pests E. kuehniella and E. ceratoniae at all tested concentrations.