Development of Multivoltine Foundation Crosses of Silkworm Bombyx mori L. for Tropical Conditions

Abstract

The newly selected foundation stocks namely PM, HB4, MO6, ND2, ND5, ND7, ND10, NDV6, NP1, NP4, PV1 and Mcon1 from the multivoltine germplasm stocks were utilized in different combinations to prepare multivoltine hybrids and selection and development of better performing hybrids as multivoltine foundation crosses. Out of the 105 hybrid combinations produced six promising hybrids were shortlisted based on their performances for the selected economic traits in all the three seasons of the year. The shortlisted crosses namely (PM×MO6), (PM×ND10), (HB4×MO6), (HB4×PM), (ND10×PM) and (NDV6×PM) were isolated as multivoltine foundation crosses suitable for tropical conditions based on the better expression of traits such as fecundity, hatching percentage, larval weight, larval duration, effective rate of rearing (ERR), cocoon weight, shell weight, shell ratio and pupation rate. Among the crosses, (ND10×PM) recorded the highest fecundity (482 eggs), cocoon weight (1.426 g), shell weight (0.263 g) and followed by (HB4×MO6) and (PM×MO6) that recorded better shell ratio of 18,69 and 18,56 respectively indicating better productivity. (PM×ND10) showed the highest hatching percentage (95.24%). All the crosses recorded the ERR that ranged from 92.00 to 94.00%, and the pupation percentage (92.85 to 94.21) indicating good adaptability under tropical conditions.