Efficacy of phytochemical-functionalized silver nanoparticles to control Flacherie and Sappe silkworm diseases in Bombyx mori L. larvae

Abstract

Plant extracts comprise a complex mixture of numerous phytochemicals including important alkaloids and polyphenols that can reduce metal ions, and comprise unsaturated compounds such as α-linolenic and carboxylic acid that acts as stabilizing agents in the greener assembly of nanomaterials. The present study demonstrates the role of phytoconstituents from flowers of Tridax trilobata (T. trilobata) in the synthesis of silver nanoparticles (AgNPs) that investigates their effects on the growth and development of the silkworm Bombyx mori L. besides controlling the occurrence of Flacherie and Sappe microbial diseases. FTIR and ¹³C NMR spectral studies confirmed the in situ role of phytochemicals from the flower extract responsible for the reduction of silver ions to AgNPs with crystalline structure, which is confirmed by XRD analysis. Compared to pure alkaloids and polyphenols, AgNPs synthesized with crude flower extract displayed synergistic antibacterial activity against Flacherie and Sappe microbial strains such as B. subtilis, S. aureus, E. coli, B. cereus, Aerobactercloacae, and S. typhi. Furthermore, AgNPs prevented the growth of biofilms in a concentration-dependent manner and an increase in inhibition is observed with concentration augmentation from 0 to 50 µg/mL. In addition, the biosynthesized AgNPs increased the feeding efficiency and improved the body weight and shell weight of Bombyx mori L. larvae, pupae, and cocoons. Overall, this integrated study found that AgNPs were effective in reducing Flacherie and Sappe disease caused by the consumption of bacterially contaminated mulberry leaves, thus improving the survival rate of Bombyx mori L. and eventually improving the crop yield through insights into the anti-biofilm activity of phytochemical-adorned AgNPs.