🐞 Sericulture — Mulberry Cultivation and Rearing

Leaf quality and rearing hygiene together determine cocoon quality, silkworm survival, and final profitability in sericulture.

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Mulberry Cultivation

Mulberry (Morus spp.) is the sole food plant of the silkworm Bombyx mori, and the quality of mulberry leaves directly determines the health and silk output of silkworm rearings. The most commonly cultivated species in India are Morus alba and Morus indica. Important improved varieties include V-1 (high yielding, suitable for irrigated conditions), S-36 (widely cultivated in Karnataka), S-1635, and AR series varieties developed by the Central Sericultural Research and Training Institute (CSR&TI), Mysuru.

Mulberry is propagated through stem cuttings (6-8 inches long, pencil thickness) planted during June-July or November-December. Plant spacing varies with the cultivation system: bush plantation (90 cm x 90 cm) is the most common for leaf production, while tree plantation (1.8 m x 1.8 m) is used in certain regions. Mulberry requires well-drained loamy soil with a pH of 6.2-6.8, adequate irrigation, and application of FYM (20 tonnes/hectare/year) along with NPK fertilizers (300:120:120 kg/hectare/year for irrigated conditions). Regular pruning at intervals of 60-70 days ensures a continuous supply of tender, nutritious leaves.

Silkworm Rearing House

The rearing house should be well-ventilated, with temperature maintained at 24-26 degrees Celsius and relative humidity at 75-85% during the larval period. Young-age silkworms (first to third instars) are reared in a separate room under controlled conditions, a practice called chawki rearing. Chawki rearing centres provide young-age worms to farmers, ensuring uniform growth and disease-free batches. Rearing beds are prepared on bamboo trays or wooden stands, with chopped mulberry leaves spread evenly.

Disinfection and Hygiene

Silkworm diseases can cause devastating losses if hygiene protocols are not followed. Before each rearing season, the rearing house, equipment, and surrounding area must be thoroughly disinfected. Formalin (2% solution) is used for spraying rearing rooms, trays, and tools. Bleaching powder (slaked lime + bleaching powder in 9:1 ratio, known as Vijetha) is dusted over rearing beds as a bed disinfectant to prevent bacterial and fungal infections, particularly grasserie (nuclear polyhedrosis virus), flacherie (bacterial), muscardine (fungal), and pebrine (microsporidian).

Mounting and Cocoon Harvesting

When fifth-instar larvae become mature (translucent body, wandering behaviour), they are transferred to mountages for spinning. Mountages can be rotary (chandrike), bamboo spiral, or plastic collapsible types. Adequate space must be provided so that each worm can spin a uniform cocoon without forming doubles (two worms in one cocoon). Cocoons are harvested 5-7 days after mounting. Good cocoons are oval, firm, uniform in colour, and free of stains or uzi fly (Exorista bombycis) emergence holes. They are sorted, deflossed (outer floss layer removed), and sent to the market or reeling units. Average cocoon yield in India ranges from 50-70 kg per 100 disease-free layings (DFLs) for bivoltine hybrids.

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Summary Cheat Sheet

• Mulberry agronomy is the foundation of productive silkworm rearing.
• Rearing environment control is critical across all instars.
• Disinfection prevents major bacterial, viral, fungal, and microsporidian losses.
• Proper mounting and cocoon grading improve reeling outcomes.

References

1 source • [1]

[1]

Standard sericulture rearing and mulberry management references used for lesson preparation.