Effect of medicinal plants on cocoon parameters of PM×CSR2 inoculated with BmNPV and Staphylococcus sciuri

Abstract

The silkworm Bombyx mori L. is an economically important insect and is prone to many diseases, including flacherie. To manage this disease, chemical based bed disinfectants are being used. These bed disinfectants leave residual toxicity in the rearing bed and inside the rearing house. Given these constraints, using plant extracts and their biomolecules was found to be an alternative to manage the grasserie and flacherie diseases. The leaves of Adhatoda vasica and Phyllanthus niruri contain many secondary metabolites that possess antimicrobial properties against a wide range of pathogens. The aqueous and methanolic leaf extracts of A. vasica and P. niruri administered to fourth and fifth instar batches of silkworm (PM×CSR2) recorded the maximum cocoon weight (1.94 and 1.81 g) shell weight (0.326 and 0.298 g), pupal weight (1.58 and 1.46 g) and shell ratio (17.65 and 16.69%) in methanolic extracts of P. niruri, followed by A. vasica, aqueous extract of P. niruri and A. vasica. Whereas the inoculated (BmNPV and S. sciuri) batches also recorded the same trend of observations (1.56 and 1.64., 0.255 and 0.271., 1.24 and 1.32 g., 16.21 and 16.05 %) in both fourth and fifth instar silkworms compared to their controls.