Heavy metals bioaccumulation in the food chain of the silkworm Bombyx mori L

Abstract

Anthropogenic and natural sources can be considered as the major sources of heavy metal release into environment. Highly toxic and reactive concentrations from such metals proposed to enter soils and groundwater, bioaccumulation in food webs, and adversely affect biota. Silkworm is the most important natural manufacture. Introduced study aims to investigate the effect of heavy metals accumulation in the harvestable parts of the plants like leaves is the route to the tropic levels in the food chain of the silkworm (Bombyx mori). The biological parameters were assessed to show the impact of heavy metals pollution on the silkworm life cycle and productivity. The results of the X–rays’ analysis of soil and plant leaves samples showed that there were significant differences between the concentrations of heavy metals in different soils. The higher concentrations were Zn > Cr > Cu > Pb > Cd > Sr, from the site I, and site II and this may be due to the irrigation by contaminated water with heavy metals, but the lower concentrations were found in the control soil which irrigated by treated water (tap water). The higher heavy metals concentrations in the leaves were Zn > Cu >Pb > Cr > Cd, from the site I, and site II. But the lower concentrations were found in control leaves sample. Moreover, the pollution in the silkworm food chain lead to general reduction in the growth rate of the larval stages, the weight of cocoon, cocooning percentage, the Effective Rate of Rearing, and the silk yield. It also results in increasing the mortality rate of larvae. It is recommended that heavy metals pollution in the food chain of silkworms should be strictly monitored.