Effect of supplementing the feed with copper and zinc on the rearing performance of silkworm (Bombyx mori L.)

摘要

Effect of supplementing copper and zinc in the silkworm feed on the economic traits of the silkworm, Bombyx mori L., was assessed. Copper sulphate administration at 5 to 100 ppm decreased the pupation rate from 81 to 52%, while zinc sulphate at 10 to400 ppm decreased it from 63 to 57%. Combination of copper sulphate and zinc sulphate resulted in a decrease in pupation from 85 to 28%. Though this pupal mortality was significant in treated batches, effect on the actual cocoon yield was not significant except in the highest concentration tried (100 and 400 ppm of copper and zinc, respectively). Cocoon weights and shell percentages did not show statistically significant variations among the treatments. High concentration of copper sulphate used aloneat 50 ppm and in combination with zinc (100 + 400 ppm) caused significant reduction in shell weight and shell percentage. The deleterious effect on survival was alleviated when 5% lime solution was added in the treatments before feeding the silkworms with treated leaves. The results indicate the desirability of treating mulberry leaves with lime when copper and zinc contents in mulberry leavescross the safe limits.