Effects of TiO sub(2) NPs on Silkworm Growth and Feed Efficiency

Silkworm (Bombyx mori) (B. mori) is an economically important insect and a model species for Lepidoptera. It has been reported that feeding of low concentrations of titanium dioxide nanoparticles (TiO sub(2) NPs) can improve feed efficiency and increase cocoon mass, cocoon shell mass, and the ratio of cocoon shell. However, high concentrations of TiO sub(2) NPs are toxic. In this study, we fed B. mori with different concentrations of TiO sub(2) NPs (5, 10, 20, 40, 80, and 160 mg/L) and investigated B. mori growth, feed efficiency, and cocoon quality. We found that low concentrations of TiO sub(2) NPs (5 and 10 mg/L) were more effective for weight gains, with significant weight gain being obtained at 72 h (P < 0.05). TiO sub(2) NPs at 20 mg/L or higher had certain inhibitory effects, with significant inhibition to B. mori growth being observed at 48 h. The feed efficiency was significantly improved at low concentrations of 5 and 10 mg/L for 14.6 and 13.1 %, respectively (P < 0.05). All B. mori fed with TiO sub(2) NPs showed increased cocoon mass and cocoon shell mass; at 5 and 10 mg/L TiO sub(2) NPs, cocoon mass was significantly increased by 8.29 and 9.39 %, respectively (P < 0.05). We also found that low concentrations (5 and 10 mg/L) of TiO sub(2) NPs promoted B. mori growth and development, improved feed efficiency, and increased cocoon production, while high concentrations (20 mg/L or higher) of TiO sub(2) NPs showed inhibitory effect to the B. mori. Consecutive feeding of high concentrations of TiO sub(2) NPs led to some degrees of adaptability. This study provides a reference for the research on TiO sub(2) NPs toxicity and the basis for the development of TiO sub(2) NPs as a feed additive for B. mori.