Composition and insecticide potential against Tribolium castaneum of the fractionated essential oil from the flowers of the Tunisian endemic plant Ferula tunetana Pomel ex Batt

For several years, plant derived substances, in particular essential oils, have been the subject of increasing attention in their safe and ecofriendly application to crops, as a powerful alternative to chemical insecticides. For this reason, the essential oil isolated from flowers of Ferula tunetana, a Tunisian endemic plant, was investigated for the first time for its chemical profile, and its toxicity and repellency effects against Tribolium castaneum (Herbst) adults. The analysis by gas chromatography coupled with mass spectrometry (GC/MS) led to determine 92.8–99.1% of the total oil (FEO) and its fractions (F1-F12) obtained every 15 min during the hydrodistillation process. The chemical analysis allowedto identify 77 compounds. α-Pinene (14.3%), a monoterpene hydrocarbon, was the major compound of the raw essential oil. Relatively high amounts of oxygenated sesquiterpenes (44.9–76.8%) were detected, consisting mainly of epi-α-muurolol (3.6–9.5%), himachalol (6.8%) and β-chenopodiol (5.1–7.1%). Regarding the repellency assay, results demonstrated that flowers essential oil of F. tunetana and its fractions displayed interesting repellent property (93%). The median lethal dose (LD50) of the topical application of the oil was 10.44%. Fumigation with the raw essential oil gave a LD50 of 161.89 μL/L air. The overall data suggest that the F. tunetana essential oil might be used to protect stored products from pest attacks, but further studies are needed in order to better understand the synergistic relationship between the phytochemicals contained in the essential oil.