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. Recently, nano titanium silicon oxide (TiSiO4 NPs) has been used in different fields and industries. Very few toxicological data exist for TiSiO4 NPs. In the present study, the potential adverse effects of oral exposure to a single dose of TiSiO4 NPs ≤50 nm (250 mg/kg b.w.) in adult male rats were investigated through the assessment of biomarkers for serum biochemical parameters, liver DNA damage, and histopathological examination and determination of Si and Ti in the exposed rat tissues. The results revealed that there were no significant changes in serum total protein, albumin, and triglycerides content, while total cholesterol level was significantly increased 7 days after exposure. TiSiO4 NPs significantly increased superoxide dismutase (SOD), glutathione peroxidase (GPx), acetylcholine esterase (AChE), lactate dehydrogenase (LDH) activity, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) levels in the exposed rat serum, whereas alanine aminotransferase (ALT), aspartate aminotransferase (AST) activity, urea level, immunoglobulins (IgG and IgM) concentrations, progesterone, and testosterone levels were significantly decreased. The liver comet assay indices were significantly increased after 7 days post-exposure. Moreover, histopathological changes and the accumulation of Si and Ti in liver, kidney, spleen, and lung tissues of treated rats were recorded.

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Bioassays were conducted to study comparative and selective toxicity of commercial formulations of the neonicotinoid insecticides acetamiprid (Mospilan 20% SP) and imidacloprid (Imaxi 35% SC) against Bemisia tabaci (Genn.) and Spodoptera littoralis (Boisd.) using leaf dipping technique as well as Apis mellifera L. by orally mixing with food media. Based on the obtained LCR 50 Rvalues, acetamiprid was more toxic to the tested adult and nymphal stages of B. tabaci than imidacloprid. The adult stage was more susceptible than nymph. Acetamiprid showed higher toxicity to eggs, the 2P nd P and 4P th P instar larvae of S. littoralis than imidacloprid. Moreover, eggs were more susceptible to the two tested insecticides than the larval instars, and the 4P th P instar larvae were the least susceptible. Acetamiprid applied orally to honey bee workers at a field rate (50 µg a.i./ml) caused 3.33 % mortality with no symptoms of toxicity 24 hr. post treatment. The field rate of imidacloprid (265 µg a.i./ml) gave 90% mortality and obvious symptoms of poisoning were recorded 10 minutes after exposure. The LCR 50 R value for imidacloprid was 59.83 µg a.i./ml. The results revealed that the cyano-substituted compound (acetamiprid) was more toxic to the tested insect pests than the nitro-substituted compound (imidacloprid) and the later was highly toxic to honey bee. So, the efficiency and selectivity of neonicotinoid insecticides are related to the chemical group of the compound as well as the species and developmental stage of the insect.