Nitrogen Fertilizer on Mulberry Leaves and Effect on Larval and Cocoon Characteristics of Silkworm, Bombyx mori L.

Egyptian hybrid of silkworm, Bombyx mori L. was obtained from the Seric. Res. Dept., Plant Protec. Res. Inst, Agric. Res. Center. Dokki, Giza. Larvae of B. mori were fed on mulberry leaves treated with nitrogen fertilizer daily during 4^th & 5^th instar and reared under laboratory conditions of 27 ± 2 Celsius, 80 ± 5 % relative humidity. Concentrations were 0.01, 0.03,0.05 and 0.07 mg/ml. Results showed that the best concentration was 0.07 mg/ml., as parameters were 1.111g for fourth stadium larval weight and 2.207 g for fifth stadium larval weight. Mortality percentage was 28.00%. Cocoon weight, cocoon shell weight and cocoon shell ratio were 1.201g, 0.229g and 19.06% respectively. Cocooning percentage was 95.40%, silk productivity was 1.83 cg/day and absolute silk yield was 16.48g. Larval duration, pupal weight and pupation ratio were 34.40 day, 0.841g and 95.00% respectively. According to the previous study, Silkworm growth and silk characteristic were enhanced when they were fed mulberry leaves treated with nitrogen fertilizer. Thus this fertilizer appears to be worthwhile suggestion for breeder.