Field evaluation of repellency of a polyherbal essential oil against blackflies and its dermal toxicity using rat model

In the present study we have evaluated the repellent activity of mixture of Curcuma longa, Zanthoxylum limonella and Pogostemon heyneanus essential oils in 1:1:2 ratio at 5%, 10% and 20% concentration against blackflies in northeastern India. Initially the essential oil mixture tested here has been found effective against Aedes albopictus mosquitoes. The average protection recorded in 20% concentration (170.56 ± 4.0; 95% CI = 162.09-179.02) was higher as compared to other two concentrations (F = 90.2; p<0.0001; df = 53). Percentage repellency and repellency index was found to be higher in 20% concentration (p ≤ 0.017). No appreciable clinical and behavioral signs were observed in the acute dermal toxicity using rat model. No changes were observed in biochemical profiles of treatment group animals. Similarly, no prominent lesions were observed in vital organs of treatment in both the sexes. The study concludes that tested repellent is safe for use and has multi-insects repellent property.