Pediculicidal Activity of Foeniculum vulgare Essential Oil in Treatment of Pediculus capitis as a Public Health Problem

BACKGROUND: Pediculosis, caused by Pediculus spp is an important public health problem in urban and rural areas around the world. Natural compounds such as plant essential oils (EOs) have been suggested as a potential alternative for insect pest control recently. The purpose of this study was to investigate the toxicity of Foeniculum vulgare essential oil against the head louse, Pediculus capitis under laboratory conditions. METHODS: Fennel essential oil components were analyzed using GC-mass apparatus. Immersion and contact filter paper bioassays were used to evaluate fennel essential oil toxicity at the two-fold concentrations of 2.5, 5, 10, 20, and 40% against nit and nymph/adult stages of the head louse. RESULTS: Trans-anethole, α-Thujone, and limonene, which consisted of 76.08%, 10.37%, and 5.34% were the most components of fennel oil respectively. The LC(50) values for the adult /nymphs were 11.5, 6.4, 3.9, 3.1 and 2.5% and LC(99) values were 29.5, 15.2, 12.8, 10.8, and 7.4% at 10, 20, 30, 45 and 60 minutes after exposure respectively. The lethal times (LT(50)) for adults/nymphs were 5.2, 8.1, 9.5, 20.5, and 45.8 minutes and LT(99) were 138.6, 91.3, 23.8, 21.7, and 13.9 minutes in the concentrations of 2.5, 5, 10, 20 and 40%, respectively. LC(50) and LC(99) values were 2.32% and 7.36% after 5 days for the eggs. CONCLUSION: Fennel essential oil at the concentration of 15% after 20min is suggested to develop as an appropriate formulation to evaluate in clinical trials.