Effect of different grain media on sporulation, germination am virulence of Beauveria bassiana (Balsamo) Vuillemin against Spodoptera litura Fabricius larvae

A laboratory experiment was carried out to study the influence of different grain based media on sporulation, germination and virulence of Beauveria bassiana (Balsamo) Vuillemin against third instar larvae of Spodoptera litura Fabricius. Among the six grain based media, viz. barley, finger millets, maize, sorghum, soybean and wheat, highest spore production (5.39 x 10⁷ conidia ml⁻¹) and spore viability (86.6 %) was observed in conidia produced from finger millet. The production and viability of conidia increased which ranged from 5.0 to 11.5 per cent and 1.70 to 4.65 per cent, respectively, when the media was supplemented with sucrose. The conidia produced from finger millet showed highest virulence against third instar larvae of S. litura with LC₅₀ value of 1.56 x 10⁶ conidia ml⁻¹ while soybean was lowest with LC₅₀ value of 4.98 x 10⁶ conidia ml⁻¹. However, conidia produced from SDA medium showed highest spore production (6.36 x 10⁷ conidia ml⁻¹), viability (93.75 %) and virulence (0.95 x 10⁶ conidia ml⁻¹) against third instar larvae of S. litura.