Insecticidal activity of essential oil of Cinnamomum cassia and its main constituent, trans -Cinnamaldehyde, against the booklice, Liposcelis bostrychophila

Purpose: To investigate the insecticidal activity of the essential oil of Cinnamomum cassis and its main constituent compound, trans-cinnamaldehyde, against the booklice, Liposcelis bostrychophila． Methods: Steam distillation of C. cassis twigs was carried out using a Clavenger apparatus in order to obtain the volatile oils. Gas chromatography/mass spectrometric (GC/MS) analyses (HP-5MS column) of the essential oil were performed and its contact (using impregnated filter paper method) and fumigant toxicity (sealed space) determined. The bioactive constituent compound, trans-cinnamaldehyde was isolated and identified from the oil based on bioactivity-directed fractionation. Results: A total of 35 components, accounting for 97.44 % of the essential oil of C. cassis, were identified. The principal compounds in the essential oil were trans-cinnamaldehyde (49.33 %), acetophenone (6.94 %), trans-cinnamic acid (5.45 %) and cis-cinnamaldehyde (4.44 %) followed by omethoxycinnamaldehyde (3.48 %), coumarin (3.42 %) and (E)-cinnamyl alcohol (3.21 %). The essential oil displayed contact toxicity against adult L. bostrychophila with a median lethal concentration (LC50) of 55.68 μg/cm 2 as well as fumigant toxicity (LC50, 1.33 mg/l air). Trans-cinnamaldehyde exhibited strong contact and fumigant toxicity with LC50 of 43.40 μg/cm 2 and 1.29 mg/l air, respectively. Conclusion: The findings suggest that the essential oil of C. cassis and its constituent compound, trans-cinnamaldehyde, possess potentials for development into natural fumigants/insecticides for the control of booklice.