AgricINTERNATIONAL

Intrinsic toxicity of Nomuraea rileyi (Farlow) Samson was studied against different larval instars of Spodoptera litura (Fabricius) by larval-and leaf-dip method. N Rileyi when applied at concentrations between 10² and 10⁹ conidia/ml resulted in 20–83.34, 26.67–100, 20–80, 20–96.67 and 16.67–83.34 per cent mortality of first, second, third, fourth and fifth instar larvae respectively. LC₅₀ values 5.7 × 10³, 4.4 × 10⁴, 1.2 × 10³, 1.3 × 10⁵ and 8.3 × 10⁴ and LC₉₀ values 1.1 × 10⁷, 4.6 × 10⁷, 7.7 × 10⁷, 2.7 × 10⁸ and 1.5 × 10⁸ conidia/ml were for different instars. Fungus at 10⁷ conidia/ml took 6.9, 6.2, 7.1, 6.9 and 7.6 days to kill 50 per cent and 10.2, 8.9, 10.2, 9.5 and 12.6 days to kill 90 per cent of first, second, third, fourth and fifth instar larvae respectively.