Evaluation of Bivoltine Silkworm (Bombyx mori L.) Hybrids for Disease Resistance and Suitability in Subtropical Conditions

Abstract

The disease outbreak in silkworm generally hampers the silkworm larvae during the late larval period causing high mortality, formation of poor-quality cocoons or even the complete loss of entire crop, posing a significant challenge to sericulture industry. The current study was undertaken to screen the native silkworm hybrids for their resistance or susceptibility to flacherie (caused by bacterial infection) and grasserie (caused by a viral infection), particularly harmful to silkworm health and their yield potential in the subtropics of Jammu division. 12 hybrids namely U-8×PO1, ND3×PO1, PO1×U-8, U-3×U-1, JD6×U-6, U-4×U-6, PO3×ND5, U-6×ND3, ND3×NSP, ND2×NSP, SH6×NB4D2 and FC1×FC2 were selected and reared with proper rearing practices. The data was recorded for various parameters pertaining performance against disease outbreak and yield potential. The hybrids namely FC1×FC2 and U-4×U-6 demonstrated superior resistant hybrids and less susceptibility. Both the hybrids showed an incidence less than 2% for flacherie and 4% for grasserie respectively. The study found that the hybrids FC1×FC2 and U-4×U-6 can be utilized commercially to reduce disease-related losses and promote sericulture sustainability in subtropical regions. Incorporating such resistant hybrids into local practice would also provide more economic stability for farmers, reducing the hazards associated with silkworm rearing. Therefore, on the basis of current results, same two hybrids can be recommended for commercial exploitation at farmer level specifically for autumn rearing in subtropics of Jammu division.  These resistant hybrids hold great promise for improving silkworm productivity thereby enhancing the sustainability of sericulture in the region.