Repellent Activity of Eight Essential Oils of Chinese Medicinal Herbs to Blattella germanica L

Eight essential oils of Chinese medicinal herbs (Angelica sinensis, Curuma aeruginosa, Cyperus rotundus, Eucalyptus robusta, Illicium verum, Lindera aggregate, Ocimum basilicum, and Zanthoxylum bungeanum) were obtained by hydrodistillation and the essential oil of Eucalyptus robusta leaves was analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 22 components of the essential oil of E. robusta were identified. The principal compounds in E. robusta essential oil were α-pinene (28.74%) and 1,8-cineole (27.18%), spathulenol (6.63%), globulol (6.53%) and ρ-menth-1-en-8-ol (5.20%). The 8 essential oils and two main components, α-pinene and 1, 8-cineole of the essential oil of E. robusta were evaluated repellency against nymphs of the German cockroaches. Strong repellency (Class V) was obtained for Cyperus rotundus and Eucalyptus robusta essential oils and α-pinene and 1, 8-cineole. However, Illicium verum essential oil possessed weak (Class I) repellency. At a concentration of 5 ppm, all the 8 essential oils and the two compounds showed repellent activity after one hour exposure. At 1 ppm concentration, essential oil of Cyperus rotundus showed strong repellency and Class IV repellency was obtained for essential oil of E. robusta and the two compounds after one hour exposure. However, essential oils of I. verum and Lindera aggregata showed strong attractiveness to the German cockroaches at a concentration of 1 ppm.