Influence of the addition of isolated soy protein and silver nanoparticles in the diet of Bombyx mori on larval development and silk production

Silk derived from the cocoon of the Bombyx mori (Linnaeus, 1758) plays an important role in the global economy. During the larval period, this insect feeds exclusively on mulberry leaves or on artificial diets that include mulberry leaves in their composition. Protein supplementation of silkworm diets has been explored as a strategy to optimize production performance. Silver nanoparticles (AgNPs) have been tested as a supplementation option, potentially stimulating insect feeding activity. This study's purpose was to analyse the effects of adding isolated and combined soy protein with silver nanoparticles incorporated on mulberry leaves during the B. mori feeding process. The group fed with AgNPs presented the highest body (5.29 g) and cocoon weight (2.19 g) among the groups tested. The group supplemented with silver nanoparticles and 2% isolated soy protein (S2Ag) exhibited a synergistic effect, resulting in lower leaf consumption, but with a silk conversion rate of 24.1%, similar to that of the control. These results are possibly related to differences in the expression of the silk genes fibroin and sericin. The AgNPs group showed higher expression of the heavy‐chain fibroin ( H‐Fib ) gene, and the S2Ag group showed higher expression of the sericin‐1 and sericin‐2 genes at the end of the 5th instar. These findings suggest potential practical applications of dietary supplementation with isolated soy protein and silver nanoparticles, both for larval development and for optimizing silk production, underscoring the importance of understanding the toxicological effects of these components in the context of sericulture.