In vitro Investigation of the Pediculicidal Activities of the Volatile Oil Components of Some Medical Plants Raised in Turkey

OBJECTIVE: The human head louse Pediculus capitis has recently acquired resistance to commercially available insecticides, which has expanded the search concerning the pediculicidal activities of some herbal products. The present study aimed to assess the in vitro pediculicidal activities of volatile oils extracted from 10 medical plants raised in Turkey: Rosa damascena (red provins rose), Pelargonium graveolens (geranium), Lavandula angustifolia (lavender), Salvia triloba (salvia), Rosmarinus officinalis (rosemary; two different chemotypes), Citrus bergamia (citrus tree), Cymbopogon nardus (citronella), Citrus limonum (lemon), and Cymbopogon flexuosus (lemongrass). METHODS: Head lice obtained from school children in Manisa Province were initially grouped as adults and nymphs and were then kept under optimal conditions (temperature of 27°C and humidity of 50%). A pinch of hair and filter paper were placed in Petri dishes and seven adults and seven nymphs were separately put in Petri dishes. The extracts obtained from each volatile oil were dropped on the lice specimens. RESULTS: The active movement of the external (antenna and legs) and internal (midgut and intestine) organs of the lice was monitored and recorded starting from 5th min for 24 hours by 10 to 30 minutes intervals. The time of death was defined as the loss of active movement and cessation of intestinal activities of lice. The results were analyzed using Statistical Packages for the Social Sciences (SPSS) version 15. CONCLUSION: The results showed that the volatile oil of Rosmarinus officinalis (two different chemotypes) was more effective than the other oils.