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Disease-Free Layings (DFLs)

Disease-Free Layings (DFLs) are certified mulberry silkworm egg sheets produced in licensed grainages and supplied to commercial sericulture rearers. They are the foundational input for every silkworm rearing batch and the principal lever by which the sericulture sector controls pebrine and other transmissible silkworm diseases.

Composition

A DFL is a sheet or cellular tray bearing eggs of Bombyx mori from female moths that have been individually tested by mother-moth examination for the microsporidian parasite Nosema bombycis (cause of pebrine) and other transmissible pathogens. Eggs from infected moths are discarded; only mothers testing negative contribute eggs to a certified DFL lot.

Regulatory framework

In India, the production and distribution of DFLs is regulated by the Central Silk Board (CSB) under the Silkworm Seed Regulations, 2010, framed under the Central Silk Board Act. The National Silkworm Seed Organisation (NSSO), Bengaluru, established in 1975, is the apex agency for production and distribution of bivoltine and multivoltine commercial DFLs. NSSO's Silkworm Seed Production Centres and Basic Seed Farms are ISO 9001:2015 certified. Registered private producers are required to produce at least five lakh DFLs per annum from the third year of registration onward.

Target use

DFLs are supplied to Chawki Rearing Centres (Chawki Rearing Centre), which incubate the eggs and rear the worms through the first two instars before passing them on to farmers. Bivoltine hybrids (Bivoltine Silkworm) such as CSR2 x CSR4 are the most widely distributed DFL types in South India.

Safety and certification

Quality certification is issued by Silkworm Seed Technology Laboratories and CSRTI for mulberry silkworm. Each lot carries a hatch-percentage and disease-free certification; lots failing mother-moth examination must be destroyed under regulatory supervision. The system underpins downstream cocoon quality and market price (see Cocoon Marketing Csb Auction).

See also: Bivoltine Silkworm, Chawki Rearing Centre, Mulberry Cultivation Sericulture, Cocoon Marketing Csb Auction, Silkworm Rearing Shed.

References

  1. Central Silk Board Silkworm Seed Regulations, 2010. Government of India.
  2. National Silkworm Seed Organisation. Central Silk Board.
  3. Silkworm Seed Legislation Act overview. Agriculture Institute.