MSc

Silkworm rearing experiment was conducted in the rearing house of the sericulture section in the Department of Agricultural Entomology, College of Agriculture, Vellayani in 93 – 94 to identify a pure race and crose breed suitable for rearing in the southern districts of Kerala, with reference of productivity and commercial quality of cocoons.
The trial was conducted with completely randomized design and the treatments were replicated thrice. Four replications were used for studying the fecundities and female pupal weight of pure races. The experiment was repeated in three seasons viz. cold season during December – January, summer season February – March and rainy season during May – June.
The percentage of missing larvae during early instars was least in the cross breeds which were on par and pure races suffered heavy loss.
Cross breed PM X NB 4 D2 was superior to others in case of total larval duration disease incidence, percentage of spinning and cocoons yield. Among the bivoltines NB4 D2 performed best with shortest larval period, less disease incidence, higher percentage of spinning and higher cocoon yield. It was superior to other bivoltines during most seasons. It consumed maximum food had highest growth index and larval weight in all seasons. Cocoon characters viz. shell weight, shell ratio, cocoon size and reelability of cocoons were also higher. Single cocoon weight, fecundity and female pupal weight were higher in KA.
NB7 was heavily infected with diseases in stock rearing it self.
Of the cross breeds, PM x NB4D2 was superior to other cross breeds in respect of all parameters during the different seasons except in single cocoon weight. In this case PM x KA performed well.
Leaf consumption, weight, length and growth index of fifth instar larva, percentage of spinning and yield of cocoons, size of cocoons, single cocoon weight, shell weight, shell ratio, fecundity and female pupal weight were reduced in summer season. But disease incidence was increased and missing percentage of larvae during early instars, total larval duration, and reelability were not affected by climate.