एरी रेशम कीट

Samia species of India

Life cycle

Adults do not feed. The fifth instar alone accounts for about 82 % of lifetime leaf intake — which is why late-age leaf supply, not early-age, is the binding constraint on how many dfls a holding can carry.

Eco-races and pure lines

Twenty-six eco-races of Samia ricini have been characterised and are conserved at CMER&TI, Jorhat, described against ten descriptors covering hatching, larval weight and duration, effective rate of rearing, fecundity, larval and cocoon colour, shell weight and shell percentage. Most produce white cocoons; Kokrajhar, Barpeta, Cachar and Rongpipi produce brick-red cocoons, and five further eco-races segregate for both. Six pure-line strains have been isolated on larval colour and marking.

YP Yellow Plain · YS Yellow Spotted · YZ Yellow Zebra · GBP Greenish Blue Plain · GBS Greenish Blue Spotted · GBZ Greenish Blue Zebra.

The C2 breed

C2 is a registered high-yielding hybrid developed at CMER&TI by directed selection and hybridisation of SR-018 (Genung) × SR-001 (Borduar). It outperforms local eco-races on every economic character and exceeds the Central Silk Board Hybrid Authorization Committee norms on cocoon yield, single cocoon weight, shell weight and shell percentage. It is best fed on NBR-1 castor, a non-bloomy red cultivar, and also performs on kesseru, borpat, tapioca and borkesseru. It is sensitive to summer heat and needs controlled temperature and humidity.

C2 falls marginally short of the HAC norm on hatching (83.91 against 85.00) and effective rate of rearing (84.02 against 85.00) while exceeding it comfortably on the four yield characters — the trade-off is stated here rather than rounded away.