Chemical Composition and Insecticidal Activity of the Essential Oil Derived from Phlomis umbrosa Against Two Grain Storage Insects

Water-distilled essential oil from Phlomis umbrosa Turcz. (Lamiaceae) flowering aerial parts was analyzed by gas chromatography-mass spectrometry (GC-MS). Forty-one compounds, accounting for 97.0 % of the oil, were identified and the main components of the essential oil of P. umbrosa flowering aerial parts were geranial (16.5 %), linalool (13.3 %), cis-geraniol (7.4 %), beta-caryophyllene (6.3 %), beta-myrcene (6.2 %), 1,8-cineol (5.3 %), 4-terpineol (5.1 %) and myristicin (5.0 %). The essential oil of P. umbrosa possessed contact and fumigant toxicity against two grain storage insects, Sitophilus zeamais and Tribolium castaneum adults (for contact toxicity LD50 values were 23.76 mu g/adult and 10.52 mu g/adult; for fumigant toxicity LC50 values were 8.15 mg/L and 5.62 mg/L air against S. zeamais and T. castaneum, respectively).