ABSTRACT
A village scale trial of Deltamethrin (K-othrin), formulated as a 2.5 per cent wettable powder and applied as a residual spray at a dosage of 25 mg/m2, was carried out against both anopheline and culicine mosquitoes, in Vikas Nagar village, Loni PHC, Distt. Ghaziabad (U.P.) in the month of August, 1985. Deltamethrin was found to be effective in reducing the overall vector population for about 10 to 12 weeks. Contact bio-assays also indicated that the insecticide has a residual life of about 12 weeks both on mud and cement plastered surfaces. No mortality was observed in bioassays against airborne effect of the insecticide sprayed on the walls. Twenty-four hour survival rate of the vector population was observed to be below 50 per cent upto 8 to 10 weeks. Observations indicated excito-repellent effect on mosquitoes forcing exodus from treated areas.