Adoption of Cold Reeling as a tool of Selection in the Breeding of “Nistari”: A Multivoltine Breed of Mulberry Silkworm (Bombyx. mori) in West Bengal, India

Abstract

Mulberry silkworm (B. mori) is an economic insect reared for silk. Economic traits of silkworm are highly influenced and deteriorated by fluctuating environmental conditions arising due to global warming.  Artificial selection has always played a crucial role in silkworm domestication to improve economic traits. Filament length is important from the perspective of mulberry sericulture. Nistari lines (“Marked” and “Plain”) which is a ruling multivoltine breed in West Bengal, India, have short filament length and economic traits are observed to be deteriorated. Selection of parents with high filament length is hard as the pupa corresponding with higher filament length is sacrificed during the process of reeling in hot temperature in conventional reeling. “Cold reeling is an alternative reeling, devoid of hot temperature, thereby enabling the rescue of pupae for further metamorphosis. Cold reeling can be adopted to select parents with higher filament lengths in mulberry silkworm for successive generations. The present study attempted to increase the filament length of “Marked” and “Plain” lines of Nistari, by selecting parents with high filament length for six consecutive generations by implementing cold reeling. A gradual increase in filament length was observed, in both the Nistari lines over six generations. This approach could enhance the economic value of Nistari silkworms and may be applicable to other breeds, potentially boosting silk production in West Bengal."