Success in sericulture depends largely on major factors like, breed, seed and feed. The silkworm breeds play an important role for high cocoon yield and silk quality. If the cocoons, which form the basic raw material for raw silk, are from bivoltines will definitely be superior with high silk content. Besides, they possess longer filament length, higher neatness, cleanness, less size deviation, low boil-off ratio, higher tensile strength and less variation in evenness. Hence, bivoltine cocoons form suitable raw material for the production of gradable raw silk as compared to polyvoltine x bivoltine cocoons. The Indian powerloom sector is in need if bulk quantity of uniform quality silk suitable to these high speed powerlooms. At present, to meet the skeletal demand of the powerloom sector, bivoltine raw silk is being imported. Thus, to save foreign exchange and also to achieve quantum jump in export of silk fabrics and to create further diversification in silk textiles vis-à-vis to give higher returns to t he farmers, enhanced production of quality silk, which has to necessarily come from bivoltine cocoons, is necessary. Earlier, the production of bivoltine silk, the potential resource for not only earning foreign exchange but also an income generating enterprise was very much limited due to non-availability of productive hybrids with superior yarn quality.

However, the concerted efforts of this laboratory for the last three decades has led to the development and introduction of CSR breeds and their hybrids which in turn have significantly contributed not only to the quantitative but also to the qualitative improvement of raw silk production. Accordingly, five single hybrids namely, CSR2 x CSR4, CSR2 x CSR5, CSR3 x CSR6, CSR12 x CSR6 and CSR16 x CSR17 and one robust hybrid, CSR18 x CSR19 have developed and authorised by Central Silk Board for commercialization. Besides, one productive double hybrid, (CSR2 x CSR27) x ( CSR6 x CSR26) and one fine denier hybrid, CSR48 x CSR4 and two cocoon colour sex-limited breeds, CSR8 (SL) and CSR2(SL) (Nandi) have been developed. Of late, considering the importance of the introduction of an exclusive bivoltine hybrid to bring quantitative and qualitative improvement in sericulture, these CSR breeds and hybrids are being extensively reared by the farmers of South India.

• Development of productive bivoltine single hybrids suitable for the tropics
• Development of robust bivoltine hybrids tolerant to high temperature for rearing throughout the year.
• Development of productive bivoltine double hybrids suitable for the tropics.
• Development of viable cocoon colour sex-limited bivoltine breeds to be used as male component with polyvoltines
• Development of fine denier bivoltine breeds with longer filament length for specific industrial requirement.
• Development of sustainable bivoltine single and double hybrids suitable for the tropics.

Cocoons of CSR2 x CSR4	Cocoons of NANDI (CSR2-SL)
Cocoons of Double hybrid - (CSR2 x CSR27) x (CSR6 x CSR26)	Cocoons, silk and fabric of thin denier hybrid - CSR48 x CSR4

1. Evolution and maintenance of bivoltine silkworm breeds.
2. Evaluation of bivoltine hybrids.

Silkworm breeding: Evolution and maintenance of productive, robust, sex-limited and fine denier bivoltine silkworm breeds and evaluation of these hybrids for their suitability in the field.

1. Breeding for the improvement of viability in bivoltine silkworm breeds / hybrids (AIB 3175)
2. Development of silkworm breeds / hybrids for special characters (AIB 3176)
3. Maintenance of bivoltine silkworm races (AIB 3294)

• Training on Silkworm breeding and silkworm race maintenance technology.
• Ph.D guidance- Four recognized Ph D. guides affiliated to Mysore University.
• Supply of layings of promising breeds to different DOS and CSB units.

1. Air-conditioned rearing house to carry out rearing of silkworm related to breeding work.
2. Facility for production of Disease free laying of silkworm.
3. Incubation cambers for incubating silkworm eggs.
4. Walk in-cooler for preserving silkworm moths during Grainage operation.
5. Controlled Environmental chambers for conducting rearing for stress breeding.
6. Reeling unit for conducting evaluation of post-cocoon parameters.
7. Facility for conducting single moth testing to identify diseases during egg production.

One hundred and Eighteen (118).

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(i) Multivoltine Breeding Laboratory is engaged in the development of multivoltine breeds and multiplication of multivoltine x bivoltine hybrids suitable for tropical and sub-tropical climatic conditions of South India. During the last few years, the laboratory has developed two multivoltine x bivoltine hybrids namely RD1 x NB18 and BL23 x NB4D2 for rain-fed areas and four productive multivoltine x bivoltine hybrids viz. P2D1 x NB18, MY1 x NB18, BL24 x NB4D2 and BL43 x NB4D2 for irrigated areas. These hybrids were authorized by Central Silk Board, Bangalore. One multivoltine x multivoltine hybrid, Varuna (BL24 x C. Nichi) for rain-fed areas and one multivoltine x bivoltine hybrid, Cauvery (BL67 x CSR101) for irrigated areas have been authorized during 2005. Recently, a new promising multivoltine x bivoltine hybrid, Jayalakshmi (ND7 x CSR2) developed in the Laboratory. The new hybrid produces A-2A grade silk with a renditta of 6-6.25. A total quantity of 1.75 lakh dfls were tested with the farmers of Karnataka, Andhra Pradesh and Tamil Nadu recorded an yield of 60-80kg/100 dfls and cocoons fetch higher rate of Rs.20-25/kg compared to existing ruling hybrid PM x CSR2. D1 x CSR2, a new multivoltine x bivoltine hybrid meant for rainfed areas producing a gradable silk with renditta of 7.5-8 and recorded an average yield of 42.5 kg/100 dfls is being popularized. Three new multivoltine x bivoltine hybrids viz. NDV6 x CSr2, ND5 x CSR2 and NP1 x CSR2 are being evaluated at Technology Validation and Demonstration Centre (TVDC) of CSR&TI, Mysore. The new hybrids are tolerant to flacherie, high temperature and grasserie diseases respectively.

Cocoons of new multivoltine x bivoltine hybrid ND7 x CSR2

Cocoons of new multivoltine x bivoltine hybrid D1 x CSR2

• Development of productive multivoltine x bivoltine hybrids suitable for tropical and semi-arid zones.
• Improvement of fibre quality in productive multivoltine x bivoltine hybrids.

Silkworm development and evaluation.

Silkworm Breeding, multiplication and Maintenance.

1. Improvement of silk quality in polyvoltine races of the silkworm Bombyx mori L. (AIB-3372).
2. Application of parthenogenetic engineering in the development of superior breeds/hybrids of the mulberry silkworm Bombyx mori L. (DST9531)
3. Evaluation of new multi x bi and multi x multi hybrids and studies on reproductive behaviour in new multivoltine breeds.

• Guiding of Ph.D students.
• Training on multivoltine silkworm race maintenance.
• Multiplication and supply of new hybrid dfls.

Eighty five (85).

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