Nanoparticles are a cause for concern because of their potential toxic effects on human health and the environment. The aim of this study was to assess the toxic effect of chitosan-coated magnetite nanoparticles (11.00±4.7 nm) on Drosophila melanogaster through the observation of hemolymph composition, DNA damage, larval survival and lifespan of flies. Chitosan-coated magnetite nanoparticles were synthesized by coprecipitation method. Drosophila larvaes and adults were exposed to 500 and 1000 ppm nanoparticles solution. After exposure, each type of larval hemocytes was recognized. Comet assay was performed to detect the DNA damage in the hemocytes. Also, the larval survival and lifespan of exposed flies were observed. Our results showed the toxic effect of the chitosan-coated magnetite nanoparticles through the increment of hemocytes, the emergence of lamellocytes, the presence of apoptotic hemocytes and the DNA damage detected by comet assay. In addition, nanoparticles produce decreasing of larval survival and shortening of the mean and maximum lifespan. The toxic effect the chitosan-coated magnetite nanoparticles is directly associated with 1000 ppm. No DNA damage was observed at 500 ppm.

2Drosophila melanogaster hemolymph cells are confirmed as a model to study the activation 3 of immune system due to foreign stimuli like iron nanoparticles. The toxicity of nanoparticles 4 is a cause for concern due to their effect on human health and the environment. The aim of 5 this study was to detect the activation of cellular immune response in Drosophila larvae 6 through the observation of hemolymph composition, DNA damage and larval viability, after 7 the exposure to 500 ppm and 1000 ppm chitosan-coated magnetite nanoparticles for 24 hours. 8Our results showed activation of cellular immune response after exposure to the nanoparticles 9 owing to the increment of hemocytes, the emergence of lamellocytes and the presence of 10 apoptotic hemocytes. In addition, chitosan-coated magnetite nanoparticles produce DNA 11 damage detected by comet assay as well as low viability of larvae. No DNA damage is 12 showed at 500 ppm. The cellular toxicity is directly associated with 1000 ppm. 13 14 15 8 129 avoid biased determinations of the chemical compositions of the samples due to their 130inhomogeneity, we have averaged the spectra obtained from 25 points grid was averaged. 131The normalized weight average of each element and the standard deviation obtained by EDS 132 analysis are listed in Table 1. We found the organic elements that comes from chitosan, C, 133 N, and O. Chlorine comes from the inorganic salt precursors. Fe element comes from the 134 magnetite nanoparticles. Traces of Mg and S come from the extraction process.