Toxic effects of cadmium on Morus alba L. and Bombyx moril L.

A 3-year micro-plot experiment of mulberry cultivation with Cd-polluted soil and silkworm breeding experiments by feeding with exogenous or endogenous ¿Cd-polluted mulberry leaves were conducted to evaluate the toxic effects of Cd on mulberry and silkworms. There was no apparent harmful effect on mulberry plant growth at a soil Cd content of 8.49 mg/kg. At a soil Cd content of 75.8 mg/kg, a yield reduction in the leaves became apparent, whereas at 145 mg Cd/kg soil, the plants exhibited marginal growth. There was a significant decrease of the ingestive rate of leaves at an exogenous Cd content of 1.98 mg Cd/kg leaf, whereas the digestive rate decreased significantly at an exogenous Cd content of 0.50 mg/kg. The endogenous Cd content that significantly affected the ingestive and digestive rates was 1.66 mg/kg. The influence of exogenous and endogenous Cd on the biomass of the silkworms decreased with increase of the instar stage. The weight of cocoons and rate of silk reeling was significantly reduced at exogenous and endogenous Cd contents of 5.17 mg/kg and 1.66 mg/kg, respectively