Determination of the acute toxic effects of zinc oxide nanoparticles (ZnO NPs) in total hemocytes counts of Galleria mellonella (Lepidoptera: Pyralidae) with two different methods.

Zinc oxide nanoparticles (ZnO NPs) are now commonly used in many consumer products (detergents, antibacterial products, protective creams). The aim of the study is to determine the ecotoxicological effects of ZnO NPs on the survival and in the total hemocyte counts of Galleria mellonella L. 1758 (Lepidoptera: Pyralidae) with two different methods (automated cell counter and hemocytometer). A toxicity test was performed to determine the lethal concentrations of ZnO NPs on larvae by force feeding method. After 24 h the treatment, LC was 6.03 μg/10 µl and LC was 12.86 μg/10 µl for force fed larvae according to probit assay. The NP that induced changes in the total hemocytes counts were counted by optical microscopy (larvae exposed to four different doses of ZnO NPs) and by automated cell counter. Analyses of total hemocyte counts of the insect were performed with four doses (0.5, 1, 2.5, 5 μg/10 µl) <LC at 24 h upon feeding larvae revealed that a number of hemocytes did not show significant changes in all treatments compared with control in the optical microscopy counting. The similar statistically insignificant counting results were also seen in the automated cell counting results. The percentage of the dead cells (10.01%) in the 5 μg/10 µl group was significantly higher than the control group (3.03%) and showed a statistically significant difference at 24 h in the optical microscopy count with trypan blue viability test.