GK. Rajesh
Scientific Advisor, Council for Nature Conservation and Environmental Protection, CONCEPT, India
Scientific Advisor, Council for Nature Conservation and Environmental Protection, CONCEPT, India
Introduction
It is well established fact that ascorbic acid plays an important role in the nutrition of silkworm. It acts as both phago stimulant and nutrient o silkworm (Ito, 1960). Karaksy (1985) showed that ascorbic acid increases silk yield of the mulberry silkworm. Mulberry leaf itself is a rich source of ascorbic acid and contains about 1.8 mg. per gram of leaf (Legay, 1958). However Karaksy (1990) showed that silkworms fed on mulberry leaves enriched with ascorbic acid showed better growth and produced heavier cocoons. Similar observations were made by Madhu Babu (1992)
Goose berry (Phyllanthus emblica L.) is one of the richest sources of ascorbic acid. Barthakur and Arnold (1991) estimated that the berry contain 5889 ppm. Ascorbic acid. Apart from this the berry contain sugars, various minerals, amino acids and vitamins etc all of which play important role in the nutrition of silkworm and silk production (Shyamala and Bhat, 1965; Subbu Rathinam and Sulochana Chetty, 1990; Ito, 1960; and Ito, 1966). In the current experiment mulberry leaves were supplemented with goose berry extract to study its effect on growth and silk production of silkworm.
Material and methods
Mature fruits of Phyllanthus emblica were procured from the department of Horticulture, University of Agricultural Sciences, Bangalore. The fruits were crushed in a stone mortar and the juice extracted through a cheese cloth was collected in amber coloured bottles and corked air tight. From the extract 20%, 40%, 60% and 100% concentrations were prepared using distilled water as diluents. The pH of the various concentrations prepared were 4.2, 2.75, 2.73 and 2.68 respectively. Each concentration served as a treatment. A distilled water control and another control without water were also maintained. Each treatment was replicated thrice. The concentrations were prepared every day fresh and were kept under room temperature. Mulberry leaves were dipped in these solutions shade dried and fed to the larvae twice a day, other feeds being un treated.
The experiment was conducted on 360 fifth instar larvae of C-Nichi race of Bombyx mori reared as recommented by Dandin et al. (2000). Each replication carried twenty larvae. The larvae were fed on mulberry variety M5.
The observations made were: weight of five mature larvae, 5 pupae, shell weight of 5 cocoons and gain in larval weight. The data was statistically analysed.
Results and discussion
The mature larval weight did not differ significantly among the treatments. Gain in larval weight was significantly higher in control (without water), other treatments on par with each other. Pupal weight was significantly higher in the 20% solution treatment, other treatments being on par with each other. Cocoon shell weight did not differ significantly among treatments.
It was observed that the larvae did not relish the leaves treated with higher concentrations. This may be due to the low pH. It is also observed that the larvae fed on higher concentrations had longer larval duration, took more time for pupation and showed pupal deformities and high post cocoon mortality. Some larvae remained inside the cocoon without undergoing pupation. Lower concentrations did not affect pupation.
These observations call for further investigations in the same line using lower concentrations of the emblica fruit extract as a food additive to silkworms, to prolong laraval duration and to mprove silk yield.
References
Barthakur,N.N;1991, Chemcal analysis f the emblica (Phyllanthus emblica L.) and its potential as a food source, Scientia Horticlture. 47: 99-105
Dandin, S.B; Jayant Jayaswal and K. Giridhar ;2000, Handbook of Sericulture Technologies, Central silk Board, p. 195-218
Ito, T; 1960, Effect of sugars on feeding of larva of the silkworm Bombyx mori. L. J. Insect. Physiol. 5: 95-107
Ito, T; 1961, Effect of dietary ascorbic acid on the silkworm Bombyx mori. L; Nature, 192: 951
Ito,T. 1978. Silkworm nutrition: In the Silkworm an Important Laboratory Tool. Tazima,Y.(Ed.) Kodansha Ltd, Tokyo. 121-157.
Karaksy, I.A and Idris, M; 1990, Ascorbic acid enhances the silk yield of the mulberry silkworm. Bombyx mori. L. J. Appl. Ent. 109: 81-86
Karaksy, I.A; 1985, The effect of ascorbic acid on silkworm Bombyx mori. L, Alexandria J. Agric. Res. 30(2):1023-30
Legay, J.M.1958. Recent advances in silkworm nutrition. Ann.Rev.Ent.,3:75-86.
Madhu Babu. Et. Al; 1992, Effect of Ascorbic acid enriched mulberry leaves on rearing of Bombyx mori. L. Indian J. Seric. 31:111-114
Ranganna, S; 1977, Manual of Analysis of Fruits and Vegetable Products. Tata Mc. Graw Hill pub. Co. Ltd. New delhi. Pp.257
Sbburathinam, K.M and Sulochana Chetty, J; 1991, Effect of fortification of mulberry leaves with minerals to silkworm Bombyx mori. L. Indian j. Seric. 30:121-23
Shyamala, M.B and Bhat, J.V; 1965, Mneral assimilation in the silkworm Bombyx mori. L. Indian. J. Exp. Biol. 4:31-34
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