BIOEFFACY OF TWO TRADITIONAL BOTANICAL INSECTICIDES AGAINST HUMAN HEAD LICE

Two plants, Spilanthes acmella and Boenninghausenia albiflora used against the insect Pediculus humanus by the Gaddi tribals of Himachal Pradesh were presently tested for their insecticidal activity. The methanolic extracts of these plants were prepared from different parts of the plant collected in different months of the year since the active principle is known to vary in different parts of the plant and also with change in climate. Best results were obtained in the extracts made from the plants collected in the month of November. The flowers of S. acmella and the stem of B. albiflora gave the best results when crude extracts of different parts of the plant were used against the insect. When purified extracts of different concentrations made from these parts were tested against the target insect, 80% mortality was obtained with 800 ppm of S. acmella extract made from flowers and 90% mortality was obtained with 800 ppm of B. albiflora extract made from stem after an exposure of 24 hrs. The mortality remained constant at 80% even after exposure to 48 hrs for S. acmella whereas it rose to 90% on exposure to 48 hrs in case of B. albiflora. KC 50 and KD 90 values for these plant extracts showed that 50% of the population will be destroyed at 467.71ppm after 24 hrs of exposure to S. acmella extract and similar results will require 392.37 ppm for 48hrs. In the case of B. albiflora extract, the KD 50 value after 24hrs of exposure was 206.26 ppm and that after 48 hrs of exposure was 197.67 ppm.