Evaluation and selection of breeding resource material of bivoltine silkworm Bombyx mori L. suitable to tropical conditions

Breeding strategies directed towards the development of hardy bivoltine races to improve the quality and unit production of silk, warrant the selection of suitable parental material and their effective utilization. In this direction, forty seven bivoltine breeds maintained as germplasm at Andhra Pradesh State Sericulture Research Institute, Hindupur were reared under summer (high temperature (30 – 36°C) and low humidity (50 – 55%) conditions. Nine quantitative and qualitative traits of the breeds are considered for evaluation based on the Joint Scoring index method. Based on the evaluation, twenty bivoltine breeds comprising of ten oval breeds which scored lower values viz., APS₅ (2.5764), APS₇ (3.3050), APS₁₉ (3.6508), APS₁₁ (4.0610), APS₉ (4.1034), APS₃₁ (4.2272), APS₂₇ (4.2939), APS₄₅ (4.2956), APS₃₉ (4.5588) and APS₁₇ (4.7332) (oval) and ten peanut breeds for APS₄ (3.1863), APS₈ (3.2886), APS₃₂ (3.4138), APS₂₄ (3.5794), APS₁₂ (3.8078), APS₁₆ (3.9715), APS₁₈ (4.1263), APS₆₂ (4.2164), APS₆ (4.2656) and APS₁₀ (4.3777) were adjudicated as potential breeding resource material for initiation of breeding programme for the development of bivoltine silkworm hybrids suitable for tropical conditions.