Evaluation of Repellency Effect of Essential Oils of Satureja khuzestanica (Carvacrol), Myrtus communis (Myrtle), Lavendula officinalis and Salvia sclarea using Standard WHO Repellency Tests

BACKGROUND: Using special lotions and repellent sprays on skin is one of the effective methods to prevent Arthropods biting which was verified in this study. METHODS: Essential oils of four plants (Satureja khuzestanica, Salvia sclarea, Lavendula officinalis and Myrtus communis) were separately extracted by Clevenger used hydro distillation method. Then separated solutions with 10%, 20% and 40% concentrations of essential oils of plants in 99.6 % ethanol were prepared. WHO guidelines for efficacy testing of mosquito repellents for human skin were used on different concentrations of essential oils of plants, traditional repellents (DEET, 50% and 33%) as positive control, and ethanol 99.6% and naked hands as negative controls. RESULTS: In negative control groups, the number of bits were comparable (P= 0.42) and had decreasing time trends (naked hands P= 0.011, ethanol P< 0.001). In all time points, minimum bites were observed in traditional repellents and it was significantly less than the other groups (P< 0.001). The time trend in the number of bites in the other groups was positive and showed minimum number of bites in time zero in all groups. We also found that the concentration of repellents had association with the number of bites. The maximum and minimum numbers of bites were observed with 10% and 40% concentrations respectively in all groups. CONCLUSION: Essential oils of Salvia sclarea, Lavendula officinalis and Myrtus communis have repellency effect, even with 10% concentration of essential oils.