Chitosan-mediated Resilience in Bacterial Infected Silkworms: A Study on Grainage Parameters

A biological assay was conducted to evaluate the efficacy of chitosan extracted from silkworm (Bombyx mori) pupae in mitigating bacterial infections and improving key grainage parameters in infected silkworms. Silkworm larvae (third instar, FC1×FC2 hybrid) were orally inoculated with Staphylococcus aureus and Bacillus thuringiensis, then treated with leaf-coated chitosan at 3500, 4000, 4500 and 5000 ppm; commercial chitosan and ampicillin at 1000 ppm served as controls, along with solvent, absolute and bacteria-free groups. Treatments were applied at five time intervals (6, 12, 18, 24 and 30 hours post-inoculation). The endpoints included moth emergence rate, deformed moth rate, fecundity (eggs/worm) and egg-hatching rate. Uninfected controls achieved approximately 95.9 per cent emergence and 3.8 per cent deformed moths. Ampicillin treatment at 6 hpi resulted in 85.1 per cent emergence, 10.6 per cent deformity, 612 eggs fecundity and 95 per cent hatching in infected groups. Among chitosan treatments, 5000 ppm dose applied at 6 hpi delivered the best performance, with approximately 82.0 per cent emergence, 13.9 per cent deformity, 582 eggs and 94.6 per cent hatching.