Biochemical biomarkers of lesser mulberry pyralid, Glyphodes pyloalis Walker, in the exposure to some applied nanomaterials in novel pesticide formulations

The activity of general esterases (ESTs), catalase (CAT) and glutathione S-transferase (GST) were used to survey the in vivo responses of Glyphodes pyloalis Walker to bare carbon nanotubes (CNTs) and synthesized carbon nanotubes/titanium dioxide nanoparticles (CNTs/TiO2-NPs). These biochemical tests were performed in the three time points of exposure (i.e. 24, 48 and 72 h) and to five concentrations (i.e. 100, 200, 300, 400 and 500 ppm). Results showed that the enhancement of treated concentrations of both CNTsand CNTs/TiO2-NPs irreversibly impaired ESTs activities when α- naphthyl acetate (α-NA) used as a substrate. Using β-naphthyl acetate (β-NA) as a substrate, inhibitory effect of both CNTs and CNTs/TiO2-NPs on ESTs activities was more intense than that of α-NA. Results also demonstrated that inhibition of GST activities generating by bare CNTs and also by CNTs/TiO2-NPs was dependent to the concentrations of treatments. CAT assays showed that the increasing CNTs concentrations over exposure time could be affected by enhancement of the CAT activities in G. pyloalis. In the similar manner to bare CNTs, the increasing CNTs when coupled to TiO2-NPs (CNTs/TiO2-NPs) over exposure time could be interfered to the CAT activities. It can be concluded that these tested enzymes are good early biochemical indicators in order to prediction and management of adverse effects of bare CNTs and also CNTs when coupled to TiO2-NPs on insects.