Preparation, characterisation and comparative toxicity of nanopermethrin against Anopheles stephensi and Culex pipiens.

Abstract

To assess the effectiveness of nanopermethrin as a potential new formulation for pest and vector control. Permethrin nanoparticles were prepared by the ionic gelation method and its structure and the formulations were designed using Box-Behnken statistical technique. The effect of independent variables (Chitosan/Permethrin ratio, tripolyphosphate quantity, sonication time) on the properties of nanoparticles was investigated to determine the optimal formulation. The size of the nanoparticles ranged from 135.27±5.88 to 539.5±24.01nm and the insecticide entrapment efficiency per cent (EE%) ranged from 7.72±1.36 to 63.59±3.17%. Anopheles stephensi larvae were then bioassayed with the nanopermethrin and compared with the results of the bioassay with the mother molecule of permethrin using a standard WHO-recommended mosquito larval bioassay kit. LC50 with permethrin and nanopermethrin on larvae of An.stephensi were 0.125 and 0.026ppm showing a 4.8 times difference. The LC50 for permethrin and nanopermethrin on Culex pipiens were 0.003 and 0.00032ppm, respectively, showing a 9.4-fold difference. Nanopermethrin is much more potent than its mother molecule against larvae of An.stephensi and Cx.pipiens.