Botanicals against Nuclear Polyhedrosis Virus infecting three breeds of mulberry silkworm, Bombyx mori L

Mulberry silkworm, Bombyx mori L, most valued for silk and other medicinal products is prone to various biotic stresses among which the disease caused by Nuclear Polyhedrosis Virus (BmNPV) is most serious as it occurs throughout the year causing losses to the tune of 30-40 per cent. Studies conducted on eco friendly management of the disease using botanicals revealed that 800 ppm hexane leaf extract of Psoralea corylifolia, Plectranthus amboinicus and the standard, gentamycin (50 ppm) were found to be effective against BmNPV infecting three different silkworm breeds, viz., cross breed, PM X CSR 2 (28.50 %, 24.00 %, 23.50 %), bivoltine hybrid, CSR 2 x CSR 4 (36.0 %, 33.50 %, 30.50 %) and double hybrid (CSR 6 x CSR 26) x (CSR 2 x CSR 27) (31.50 %, 29.00 %, 26.50 %) recording lowest larval mortality. Treated control (BmNPV@10 POBs/ml) recorded the highest mortality of 60.00 %, 75.50 % and 68.50 % respectively against cross breed, bivoltine hybrid and double hybrid. Besides the disease reduction, administration of botanicals also enhanced the economic parameters, viz., larval weight, cocoon weight, shell weight and shell ratio. Isolation of active principles from hexane extract of P. corylifolia using Thin Layer Chromatography studies (TLC) resulted in seven partially purified fractions. From the seven partially purified fractions, two fractions possessing antiviral properties were further purified using High Performance Liquid Chromatography (HPLC). Characterization of these purified fractions using Liquid Chromatography Mass Spectroscopy (LCMS) revealed the presence of two flavanoid compounds, viz., Bakuchicin and Bavacoumestan.