Performance of Multivoltine Hybrid Nistari ×M12 (W) and Cross Breed N × NB4D2 of Bombyx mori L. during Favourable and Unfavourable Season in West Bengal

In West Bengal rearing season of Mulberry is divided mainly in two parts, i.e., favourable season (November to April) and unfavourable season (May to October). Mulberry crop span is 70 days. So five harvests as well as five rearings can be done in a year. November crop (winter or Agrahani), February crop (spring or Falguni) and April crop (summer or Baishakhi) come under favourable season (dry summer) whereas June-July crop (rainy or Shrabani) and August-September crop (autumn or Aswina) come under unfavourable season (wet summer). A study was conducted from November, 2003 to November 2006 to evaluate the performance of multivoltine hybrid Nistari × M₁₂ (W) and cross breed Nistari × NB₄D₂ of Bombyx mori during favourable and unfavourable seasons. The study revealed that during favourable season performance of cross breed Nistari × NB₄D₂ is better but during unfavourable season Effective Rate of Rearing is very less and melting percentage is considerably higher in case of Nistari × NB₄D₂ batch as compared to Nistari × M₁₂ (W) batch.