Abstract
Silicon dioxide (SiO(2)) nanoparticles are chemically stable, biocompatible, abundant, and inexpensive. Moreover, they are highly surface-reactive. While these properties make them suitable for environmental applications, they also raise questions about their reactivity with environmental contaminants. This study investigated the enzyme activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), cytochrome P450 (Cyt P450), glutathione S-transferase (GST), and acetylcholinesterase (AChE), as well as total differential hemocyte counts and apoptotic index in the hemolymph, midgut, and fat body of Galleria mellonella, were investigated following exposure to an LD(50) value of SiO(2) NPs (396 μg/mL), an environmental concentration of abamectin, cadmium sulfate (CdSO(4)), and copper sulfate (CuSO(4)), both singly and in a mixture. A decrease in the total hemocyte count was observed in the groups that were singly treated with SiO(2) and CdSO(4). However, an increase was observed in the SiO(2) NPs + CdSO(4) mixture, and a decrease was observed in the SiO(2) NPs + abamectin group compared with the control. Treatment with SiO(2) NPs, CdSO(4), and abamectin singly and in mixture altered the levels of prohemocytes, plasmatocytes, spherulocytes, granulocytes, and oenocytoids. This study determined that SiO(2) NPs, CdSO(4), and abamectin lead to toxic effects in G. mellonella larvae following single and mixture applications. It was also observed that SiO(2) NPs may increase the toxic effects of environmental pollutants on the antioxidant defense and immune systems, depending on tissue differences following mixture applications.