Silkworm seed technology laboratory, Kodathi is producing P2 Dfls through Race maintenance programme in limited manner to supply selected Basic seed farms to rear and generate P1 seed cocoons for hybrid preparation to West Bengal in the event of seed crop failures. In the present investigation, Nistari ecotypes Chalsa, Balapur and Debra, M6DPC were evaluated almost for 5 years. The mean performance of these breeds was shown significant differences for the majority of the traits with excellent pupation rate. The effective rate of rearing/ 10,000 larvae (ERR) by is 8927 in Chalsa, 9118 in Balapur, in Debra 8898 and 8843 in M6DPC. The ERR by weight is Kg in Chalsa, Kg in Balapur, Kg in Debra and in M6DPC. The cocoon weight in Chalsa , and in Balapur, in Debra, and in M6DPC. The cocoon shell weight in Chalsa is and in Balapur , in Debra and in M6DPC. Cocoon shell ratio in Chalsa is , in Balapur , in Debra and in M6DPC is . Pupation rate in Chalsa is , in Balapur and in Debra and in M6DPC. Evaluation of these P2 dfls of Nistari (Chalsa, Balapur and Debra) in West Bengal at selected Basic seed farms indicated Kg/100 dfls with a good pupation rate of . In Tamil Nadu, Nistari (Chalsa) revealed an average yield of Kg/100 dfls with 95% pupation. In case of M6DPC, it revealed an average yield of Kg/100dfls with pupation rate of 94% and other traits are on par with laboratory performance. In Andhra Pradesh, an average of Kg/100 dfls (Chalsa) yield with pupation rate and excellent economic traits is indication for quality seed cocoons to realize the benefit of hybrid vigour at commercial level. | Maintenance of popular multivoltine races for seed cocoon generation and their performance at basic seed farms
