Insecticide impregnated cotton fabrics of different hydrophobicity against Aedes aegypti (Diptera:Culicidae).

Residual efficacy of synthetic pyrethroids, viz, permethrin, deltamethrin, lambdacyhalothrin and an insect repellent DEPA in cotton fabrics of different hydrophobicity was tested against Aedes aegypti. Amino silicone was used for enhancing the hydrophobicity of the fabrics. The results showed that there was an increasing trend in repellency/feeding deterrency with the increase in hydrophobicity up to 17.5 weeks at an optimum level of 30g/l. The adulticidal effect lasted for 1 to 4 weeks and this lower residual activity was attributed to the repellency of the treated fabrics. The results indicated that the residual efficacy of cotton fabrics could be enhanced by treating with an hydrophobic agent that increases the availability of the insecticide on the surface.