Studies on the Performance of Eri-Silkworm (Samia cynthia ricini Boisduval) (Lepidoptera: Saturniidae) Fed on Different Genotypes of Castor (Ricinus communis L.)
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Date
2011-06
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Addis Ababa University
Abstract
The growth, development, reproduction as well as yield of silkworms can be
greatly affected by their feed sources. In the present investigation, eight
different castor genotypes (Abaro, Acc 106584, Acc 203241, Acc 208624, Ar sel,
Bako, GK sel and local genotype) were evaluated for their importance as feed
for eri silkworms in Melkassa, East- Shewa zone, Oromia Regional State. The
genotypes showed significantly wide variation in their quantitative and
qualitative traits in field studies. Similarly, significant differences were
obtained in biochemical compositions of castor genotypes as well as rearing
performance and feeding efficiency of eri silkworms when different castor
genotypes were fed. On the other hand, relationship of biochemical
constituents of castor genotypes with rearing performance of eri silkworms
revealed strong positive correlation of nitrogen, crude protein and moisture
content of castor leaves with all larval, cocoon and grainage parameters of eri
silkworms. Among castor genotypes tested, Acc 208623 revealed 13531.9
kg/ha and 3113.1 kg/ha of fresh and dry leaf biomass yield, respectively and
1181.24 kg/ha of seed yield in field condition. Moreover, its leaf composition
reflected 75.086 % moisture, 24.908 % crude protein, 41.078 % total
carbohydrate, 17.736% crude fiber, 15.000 % ash (total minerals), 205.893
mg/100g tannins as well as 3.985 % nitrogen, 1.908 PPM phosphorus, 8027.6
PPM potassium, 155.089 PPM calcium and 17.456 PPM magnesium. Its silkworm
rearing performance indicated 8.05 g matured larval weight, 3.31 g cocoon
weight, 2.83 g pupal weight, 0.477 g shell weight and 14.424 % silk ratio,
73.18% effective rate of rearing (ERR), 78.349 % survival rate, 374.00 eggs as
fecundity and 87.00 % hatchability of eggs. Moreover, In feeding efficiency
analysis conducted for its fifth instar larva, it expressed 6.904 g/larva of
ingesta or food consumption, 3.574 g/larva digesta or food digestion, 3.330
g/larva excreta, 51.766 % approximate digestibility, 2.073 reference ratio,
0.862 relative consumption rate, 0.255 relative growth rate, 31.406 %
efficiency to convert ingested leaves to larval biomass, 64.649% efficiency to
convert digested food to larval biomass, 19.236 % efficiency to convert
ingested food to cocoon and 37.173 % efficiency to convert digested food to
cocoon. Therefore, Acc 208623, which has green stem and leaf colors, was
found to be superior and recommended to future development works.
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Biology