الفهرس 
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Abstract
This study was carried out in the laboratory of Entomology department, Faculty of Science in Mansoura University during spring and autumn 2019. The mulberry (Morus alba) leaves were collected for silkworm larvae from three sites : - Garden of faculty of Agriculture, Mansoura University. (Site I) - Delta Company of fertilizers and chemical industries. (Site II) - Garden of faculty of Science, Mansoura University. (Control) Samples of soil and mulberry leaves were analyzed to estimate heavy metals concentrations. The present study conducted to assess the impact of heavy metals accumulation on the life cycle of silkworm insect (B. mori L.) and its silk production. -The effects were clear in increasing mortality rate (50.66 %),the duration of life cycle (30.36 days), in group of site I, which had the higher concentration of Pb (2.5 mg/kg),and Zn(25 mg/kg), but it had the lowest values in Cocooning(40.12%), Pupation(40.12%), ERR(15.44%),5th larval length(5.21cm), fecundity(435 eggs), and fertility(86.11%). The maximum results in Cocooning (70%), Pupation (70.41%), ERR (97.21%), Fecundity (645eggs), Fertility (97.96%), and silk denier (1.43), were in control group which had the lowest concentration of heavy metals in the soil and mulberry leaves. - group of sit II, had the higher concentration of Cu (4mg/kg), and Cr (1.75mg/kg), it had the longest silk thread only (1407m), that may be due to the concentration of Zn (15mg/kg) in mulberry leaves which acts as modulatory factor for silk production. SEM study for the fresh cocoons from different feeding sources groups showed a significant silk fibers irregularity and silk filament diameter differences that illustrates the differences between silk quality and silk strength due to the impact of heavy metals concentration in the silkworm food chain.