Effect of Zn(II) deposition in soil on mulberry-silk worm food chain

Abstract

The present study was conducted to evaluate the entrance of Zn(II) into the food chain of Bombyx mori (silk worm) from mulberry plants irrigated using Zn(II) containing synthetic effluents. The soil, plant, silkworm and their excreta were sampled to determine Zn(II) amount by using atomic absorption spectrometry (AAS). The amount of Zn(II) deposited by synthetic effluent to soil was increased with pH of the effluent. However, the bioaccumaltion of Zn(II) in Morus alba leaves and B. mori larvae was high when the effluent pH was in the acidic range. B. mori excreted considerable amount of Zn(II) but still most of Zn(II) resided inside its body. The maximum Zn(II) amount detected in soil, leaves, larvae and
faeces were 386.51 ± 0.03, 142.85 ± 0.001, 91.375 ± 0.019 and 42.13 ± 0.69 mg/kg, respectively. Zn(II) present in B. mori body was responsible for toxic effects on its life cycle. First instar of B. mori was most affected by Zn(II) toxicity. Body length, body weight of B. mori decreased with increase in bioaccumlated Zn(II) amount in larval body. Higher Zn(II) concentration in larval body increased B. mori death rate significantly.