Evaluation of the toxicity of the essential oils of some common Chinese spices against Liposcelis bostrychophila

Fourteen essential oils of common spices in China were evaluated for insecticidal activities against the booklouse, Liposcelis bostrychophila. Five essential oils (Allium sativum, Cinnamomum cassia, Foeniculum vulgare, Illicium verum, and Perilla frutescens) exhibited strong contact toxicity against the booklice at a concentration of 0.16 μL/cm2 while only C. cassia, F. vulgare and P. frutescens essential oils possessed fumigant toxicity at a concentration of 0.04 μL/L. Based on bioactivity-directed fractionation, estragole, trans-anethole and fenchone were isolated from the essential oil of F. vulgare. Estragole and trans-anethole exhibited contact toxicity against the booklouse with LD50 values of 49.95 μg/cm2 and 57.98 μg/cm2, respectively while F. vulgare essential oil had an LD50 value of 90.36 μg/cm2. trans-Anethole (LC50 = 15.96 μg/L) possessed stronger fumigant toxicity against the booklouse than fenchone (LC50 = 73.23 μg/L), estragole (LC50 = 160.33 μg/L) and the essential oil of F. vulgare (LC50 = 34.07 μg/L).