Studies on the impact of Spirulina and Thyroxine on growth and silk production of the silkworm, Bombyx mori L.
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Date
2024
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SKUAST Kashmir
Abstract
Nutrition plays an important role in the growth and development of silkworm Bombyx mori L. which subsequently influences the cocoon production. Although the mulberry leaves are complete diet for silkworm, the supplementation with extra nutrients results in higher yields. In the present investigation entitled “Studies on the impact of Spirulina and Thyroxine on growth and silk production of the Silkworm, Bombyx mori L.” Carried out at College of Temperate Sericulture, Mirgund, during the year 2021 and 2022 rearing of bivoltine hybrid (CSR2 × CSR4) was conducted. Two fortificants viz., Spirulina and Thyroxine with three different concentrations i.e., 300ppm, 400ppm, 500ppm and 1.25ppm, 2.50ppm, 5.00ppm respectively were utilized to determine their effect on growth and development of silkworm, dietary efficiencies, commercial cocoon characters, and on biomolecules of haemolymph and silk gland. These fortificants as per treatment concentration and combinations plans were sprayed on the mulberry leaves and fed to the silkworm during 4th and 5th instar. Two controls viz., control –I (Worms fed with mulberry leaves treated with distilled water) and control –II (worms fed with mulberry leaves without any treatment) were also maintained along with treated batches. During spring season the results showed that the ingesta of (15.86g), digesta of (11.77g), excreta of (4.09g), approximate digestibility of (74.20%), efficiency of conversion of ingesta to larva of (26.74%), efficiency of conversion of ingesta to cocoon of (14.52 %), efficiency of conversion of ingesta to shell of ( 3.38%), ingesta/ g of cocoon of (96.89g) and ingesta/g of shell of (29.57g), respectively were recorded when mulberry leaves were fortified with treatment combination of spirulina (500ppm) and thyroxine (5.00ppm) During autumn season the ingesta of (14.84g), digesta of (11.74g), excreta of (4.06 g), approximate digestibility of (72.67%), efficiency of conversion of ingesta to larva of (27.67%) ,efficiency of conversion of ingesta to cocoon of (13.36 %), efficiency of conversion of ingesta to shell of (3.08%), ingesta/ g of cocoon of (7.48g )and ingesta/g of shell of (32.50g) were also observed when mulberry leaves were fortified with treatment combination of spirulina (500ppm) and thyroxine (5.00ppm) during spring season the shortest 5th age and total larval duration of (170.60, 650.60 hours ) respectively ,the highest weight of 10 mature larvae of (51.36 grams), silk gland weight of (1.67grams), silk gland length of (28.61cm), silk gland somatic tissue index of (32.14 %) , silk conversion of (32.13 %) , cocoon yield of 9301.96 cocoon / 10,000 larvae by number, cocoon yield of (21.44 kg) by weight, single cocoon weight of (2.30 g) , single shell weight of ( 0.54 g) , shell percentage of (23.30 %), pupation rate of ( 94.74 %), fecundity of (598) eggs per laying ,hatching percentage of( 98.87%) were recorded when mulberry leaves were fortified with treatment combination of spirulina ( 500ppm) and thyroxine (5.00ppm). During autumn seasons the shortest 5th age and total larval duration of (216.24, 696.24) hours respectively, the highest weight of 10 mature larvae of (49.48g), silk gland weight of (1.64g), silk gland length of (27.63 cm), silk gland somatic tissue index of( 33.15 %), silk conversion of (31.50 %) , cocoon yield of 9033.46 cocoon / 10,000 larvae by number, cocoon yield of (18.54 kg) by weight, single cocoon weight of (1.98 g) , single shell weight of (0.45 g) , shell percentage of( 23.03 %), pupation rate of (91.77 %), fecundity of (571) eggs per laying, hatching percentage of (94.85%) were also recorded when mulberry leaves were fortified with treatment combination of spirulina( 500ppm) and thyroxine (5.00ppm).In case of post cocoon parameters during spring season the longest filament length of (1149.17m) , thinnest filament size (denier) of (2.49) , the highest raw silk percentage of 18.31% , highest silk reelability of (89.25 %) . During autumn season the longest filament length of (982.00 m) , thinnest filament size (denier) (2.37), the highest raw silk percentage of (16.67 %) , highest silk reelability of (84.25%) were also recorded in the same treatment combination of spirulina (500ppm ) and thyroxine (5.00ppm) .The highest total protein content of (55.86 mg/ml) in haemolymph and (35.68 mg/g) in silk gland , total carbohydrate content of (28.93 mg/ml) in haemolymph and (25.94 mg/g) in silk gland and total lipid content of (42.19 mg/ml)in haemolymph and (34.21mg/ g) in silk gland respectively were recorded when mulberry leaves were fortified with the treatment combination of spirulina (500ppm) and thyroxine (5.00ppm). During autumn season highest total protein content of (51.13 mg/ml) in haemolymph and (31.69 mg/g) in silk gland, total carbohydrate content of (27.92 mg/ml) in haemolymph and (21.96 mg/g) in silk gland and total lipid content of (41.20 mg/ml) in haemolymph and (30.28 mg/ g) in silk gland respectively were also recorded in the treatment combination of spirulina (500ppm) and thyroxine (5.00ppm). So far as economic benefit with the application of above chemicals is concerned, the overall improvement was observed to the extent of 25 to 30 percent. Thus results in this study clearly indicates that by improving the nutritional value of mulberry leaf by fortification supports good growth and development of silkworm viz –a-viz improves the dietary efficiency, the economic and biochemical parameters significantly.
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Keywords
Bombyx mori L., Spirulina, Thyroxine, Dietary efficiency, Economic traits, Biochemical parameters, Sericulture