Analysis of the Essential Oil of Illicium henryi Diels Root Bark and Its Insecticidal Activity against Liposcelis bostrychophila Badonnel

Water-distilled essential oil from Illicium henryi (Illiciaceae) root bark was analyzed by gas chromatography–mass spectrometry. Thirty-four compounds, accounting for 97.86% of the total oil, were identified. The main components of the essential oil of I. henryi root bark were safrole (46.12%), myristicin (20.39%), and 1,8-cineole (6.17%), followed by a-cadinol (3.784%) and linalool (3.22%). The essential oil had higher levels of phenylpropanoids (66.89%) than of monoterpenoids (14.83%) and sesquiternoids (16.14%). Three constituents were isolated from the oil based on bioactivity fractionation. The essential oil possessed fumigant toxicity against booklice ( Liposcelis bostrychophila ), with a 50% lethal concentration (LC 50 ) of 380.39 mg/liter of air, while the two isolated constituents myristicin and safrole had LC 50 s of 121.95 and 322.54 μg/liter, respectively. Another constituent, 1,8-cineole, showed weaker toxicity, with an LC 50 of 1,120.43 μg/liter. The essential oil also exhibited contact toxicity against L. bostrychophila, with an LC 50 of 96.83 μg/cm 2 . Myristicin (LC 50 , 18.74 μg/cm 2 ) and safrole (LC 50 , 69.28 μg/cm 2 ) exhibited stronger acute toxicity than 1,8-cineole (LC 50 , 1,049.41 μg/cm 2 ) against the booklice. The results indicated that the essential oil and its constituent compounds have potential for development into natural insecticides for control of psocids in stored grains.