Reproductive Performance of Breeds and Hybrid of Silkworm, Bombyx mori L. with Special Reference to Egg Laying Rhythmicity

• Published in: International Journal of Industrial Entomology 2013-03, Vol.26 (1), p.22-30
• Main Authors: Saha, Atul Kumar, Kumar, N. Suresh, Chakrbarty, Satadal, Patnaik, Bharat Bhusan, Nayak, Sandeepta Kumar, Roy, Subrata, Bindroo, Bharat Bhushan
• Format: Article
• Language: Korean
• Subjects: Egg laying rhythm; Hatching performance; Photoperiod; Scotoperiod
• ISSN: 1598-3579

The reproductive performance of multivoltine breed ``Nistari`` and bivoltine breeds as NB18, P5 and a bivoltine hybrid (NB18 x P5) of B. mori were studied in different seasons in terms of total number of eggs laid, unlaid and hatching efficiency of the laid eggs to critically assess the breeds / hybrid potentiality. The bivoltine hybrid showed better performance in all the seasons as compared to the breeds investigated, as expected due to possibility of hybrid vigour. Among the breeds, bivoltine P5 had a better egg laid performance in S1 (February - March), S2 (May - June) and S3 (September - October) seasons but with an increase in the number of unlaid eggs. The hatching percentage, although didn`t show any definitive trend, still suggested a marginal better performance in the hybrid. Most importantly, egg laying rhythmicity was studied by mating the female moth at 6.00 a.m. for 3½ hours, and subse- quently allowing the laying of eggs both under BOD condition (25 ± 1°C and 85 ± 5% RH) and at ambient temperature (23 - 28°C and 74.7 ± 5%) separately. Maximum (90%) egg laid occurred from 3.30 to 7.30 pm (i.e. 4 - 6 h after decoupling). Similar laying patterns were observed when females where mated at 12 noon and decoupled at 3.30 pm, revealing that late photoperiod and early scotoperiod were favourable for egg laying in case of multivoltine breed and bivoltine prefers late photoperiod for egg laying.