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

Abstract

Objectives: To assess the effectiveness of nanopermethrin as a potential new formulation for pest and vector control. Methods: 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. Results: The size of the nanoparticles ranged from 135.27 ± 5.88 to 539.5 ± 24.01 nm 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 0.026 ppm showing a 4.8 times difference. The LC50 for permethrin and nanopermethrin on Culex pipiens were 0.003 and 0.00032 ppm, respectively, showing a 9.4-fold difference. Conclusion: Nanopermethrin is much more potent than its mother molecule against larvae of An. stephensi and Cx. pipiens.