Study on Starvation Tolerance in Few Bivoltine Silkworm Breeds of Bombyx mori L.

Abstract

Starvation during silkworm rearing may occur when mulberry leaf quality or supply is inadequate or when temperature and humidity are poorly managed, potentially reducing cocoon production. This study evaluated starvation tolerance in eight bivoltine silkworm breeds of Bombyx mori under two feeding-deprivation schedules. Fifth-instar larvae were fed for two days before starvation in Treatment 1 and for four days before starvation in Treatment 2. Survival and mortality were recorded at 24-h intervals, and haemolymph proteins from selected breeds were examined by SDS-PAGE. In Treatment 1, G1 and G2 reached 100% mortality at 216 h, whereas G3 showed only 6.67% mortality up to 120 h and CSR2 showed no mortality. In Treatment 2, mortality reached 66.67% in both G1 and G2 by 144 h, while G3 and G4 recorded 23.33% and 30% mortality, respectively, up to 120 h. No mortality was observed in CSR2, CSR26, or CSR27 under Treatment 2. Survivorship was lower in G1 and G2, and survival differed significantly among breeds across time intervals. SDS-PAGE indicated changes in haemolymph protein expression under starvation, including a band putatively corresponding to an approximately 30.1-kDa lipoprotein. G3 showed relatively high survival among the amylase-derived breeds and displayed differential protein bands. These findings identify breed-level variation in starvation response and support the further evaluation of G3 in breeding programmes for starvation tolerance.