STUDY ON EFFECT OF METHIONINE AND TRYPTOPHAN ON THE LARVAL GROWTH, COCOON CHARACTERS AND REPRODUCTIVE PARAMETERS OF ERI SILKWORM, Samia ricini Donovan
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Date
2021
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Abstract
A study on effect of methionine and tryptophan on the larval growth, cocoon characters and reproductive parameters of eri silkworm, Samia ricini Donovan was carried out during the month of December-February, 2020-2021 in the Department of Sericulture, Assam Agricultural University, Jorhat.
The study revealed that fortification of castor leaves with methionine and tryptophan significantly improved the larval growth, cocoon characters as well as reproductive parameters of eri silkworm, Samia ricini Donovan. Methionine and tryptophan supplementation especially at 500 ppm concentration found to have more pronounced effect as compared to the remaining concentrations over the control. Fortification of castor leaves with tryptophan at the rate of 500 ppm concentration resulted in maximum increment in respect of larval and cocoon parameters viz., larval weight (both full grown and matured), silk gland weight, Silk Gland Tissue Somatic Index (SGTSI), cocoon yield (g/100 nos. of larvae), cocoon weight, pupal weight, shell weight and shell ratio. Reproductive parameters including total moth emergence, male and female adult longevity, fecundity and hatching percentage also showed a notable influence in larvae fed on 500 ppm tryptophan fortified castor leaves. In case of developmental periods viz., larval (fourth and fifth instar) as well as pupal periods, a significant decrease was observed in amino acid treated batches over control and was more prominent at 500 ppm tryptophan. However, 500 ppm methionine followed by 500 ppm tryptophan reduced the incubation period. The combination treatments of methionine and tryptophan did not express much improvement in respect of these parameters when compared to the individual treatments of methionine and tryptophan. It was observed that fortification of castor leaves with methionine and tryptophan did not have any significant effect on third instar larval duration, Effective Rate of Rearing (ERR), individual male and female moth emergence as well as coupling percentage of eri silkworm.
Thus, from the present investigation it can be inferred that fortification of castor leaves with methionine and tryptophan is effective for improvement of larval growth, cocoon characters and reproductive parameters of eri silkworm. Though all the concentrations had positive impact on all the parameters but tryptophan and methionine at a concentration of 500 ppm was more efficient and exert promontory effect than other doses for improving larval growth, cocoon characters and reproductive parameters.