Chemical Science International Journal

Use of botanical environmentally friendly and biodegradable insect repellants as opposed to chemical insecticides is increasingly becoming important as an alternative method of insect control. Housefly (Musca domestica L.) has potential of transmitting pathogen causing diseases such as typhoid, cholera, bacillary dysentery, tuberculosis, anthrax, ophthalmia, and parasitic worms. The aim of this study was to evaluate the repellency of oil extracted from the leaves of Pelargonium citrosum and Rosmarinus officinalis. Extraction of essential oils was by hydro-distillation. Condensed oil extracts were collected in n-hexane and insect behavioral response tested using adult houseflies (Musca domestica L.). N, N-diethyl-m-toluamide (DEET) was used as the positive control and acetone as the negative control. The bioactive oil was then analyzed using GC-MS. The characteristic volatiles obtained from the two plants showed different compositions. P. citrosum oil comprised mainly of Linalool, Geraniol, m-Camphorene, 2-naphthalenemethanol-1,2,3,4,4a,5,6,7-octahydroalpha, Geranylangelate while R. officinalis comprised mainly of α-Pinene, , Eucalyptol, α-Terpinenol. Dose-response evaluations of these oils showed that R. officinalis oil was more repellent (LD₅₀ = 0.299 mg) than that of P. citrosum (LD₅₀ = 0.445 mg). The results provide scientific rationale for traditional use of R. officinalis and Pelargonium citrosum essential oils in control of housefly and other common insects in the household.