Larvicidal Activity of Nano- Encapsulated Lambda – Cyhalothrin Against Susceptible Mosquito Larvae (Culex Pipiens) in Comparison with Conventional form

Encapsulated lambda – cyhalothrin nanoparticles loaded in polyethylene glycol were prepared by melt dispersion method in concentration 4% and 8% of their tested conventional lambda. Larvicidal activity of encapsulated lambda nanoparticles was investigated in comparison with its conventional form against susceptible larvae of Culex pipeins after 24, 48 and 72 hrs. exposure periods. The conventional lambda showed LC_50 values equal 7 ×10^-8, 1.8 ×10^-8 and 1 ×10^-9M, during the exposure time, respectively. The reduced tested concentrations of nanoparticles (4% and 8%) were highly toxic against mosquito larvae with LC_50 values equal 4.6×10^-8, 2.9 ×10^-9 and 7.8 ×10^-10 M (for 4%) and 1.8 ×10^-8, 5.3×10^-9 and 1.2×10^-9 M (for 8%) after 24, 48 and 72 hrs. of exposure periods, respectively. The toxic effects of the low concentrations from lambda nanoparticles against Culex pipens may be due to the diffusion released of cyhalothrin with amounts equal 1.84 ×10^-9, 1.16×10^-10 and 3.12×10^-11 (in case of 4%) and 1.44×10^-9, 4.24×10^-10 and 9.6×10^-11 M (for 8%) after 24, 48 and 72 hrs., respectively. These results proposed that the encapsulated lambda-cyhalothrin nanoparticles can serve as an effective larvicide against Culex pipeins larvae at lawer concentrations avoiding the different problems of conventional form.