Effect of Digestive Enzymes-Fortified Castor Leaves on Cocoon and Reproductive Parameters of Eri Silkworm (Samia ricini Donovan)

Abstract

Sericulture is an important agro-based industry that provides employment and income to rural communities, particularly in regions like Assam where eri culture is widely practiced. The productivity and quality of silk largely depend on the nutritional quality of host plant leaves and the efficiency of digestion in silkworms. The present study was conducted during 2024–2025 at the Department of Sericulture, Assam Agricultural University, Jorhat, to evaluate the effect of digestive enzymes-fortified castor leaves on the cocoon and reproductive parameters of eri silkworm (Samia ricini Donovan). Lipase and α-amylase enzymes were used as fortification agents at three concentrations (1%, 3%, and 5%), along with a combined treatment (1% lipase + 1% α-amylase) and an untreated control. Castor leaves were fortified using the leaf-dip method and fed to larvae from the first to fifth instar during spring and autumn seasons. The results revealed that enzyme fortification significantly improved most of the economic and developmental parameters compared to the control. Among the treatments, lipase at 5% concentration recorded the best performance, showing the highest cocoon weight (3.00 g in spring and 2.36 g in autumn), shell weight (0.50 g and 0.35 g), pupal weight (2.50 g and 1.88 g), shell ratio (16.88% and 15.66%), moth emergence (92.72% and 91.68%), and adult longevity (8.50 and 9.25 days). The same treatment also resulted in the lowest defective cocoon percentage and reduced pupal duration compared to the control group. The findings indicate that digestive enzyme supplementation, particularly lipase at 5%, can be an effective nutritional management strategy for improving cocoon quality and overall productivity of eri silkworm. This approach may contribute to enhancing the efficiency and sustainability of eri sericulture.