The influence of different concentrations of Nomuraea rileyi (Farlow)Samson on the mortality of larvae of Leucinodes orbonalis (Guenee) in laboratory showed a maximum mortality at six days after spray in all the instars at 3.2x109 spores per ml. The maximum mortality of 93.06 per cent was obtained in first instar larvae followed by 84.98 per cent in second instar, 56 per cent in third instar, 48.15 per cent in fourth instar and 41.11 per cent in fifth instar at 3.20 x 109 spores per ml. Data clearly indicated that early instars are more susceptible to fungus than later instars. In general, irrespective of instars the larval mortality increased with increasing spore concentrations of the fungus. Among 11 treatments evaluated under field conditions, the combination of F. semitectum 3.6x1015+ N. rileyi 2x108+ spinosad (15 g ai/ha) and removal and destruction of infected shoots and fruits reduced the shoot and fruit infestation effectively. The maximum marketable fruit yield (136 q/ha) was obtained in T4- F. semitectum 3.6x1015+ N. rileyi 2x108+ spinosad (15 g a.i/ha). The cost economics worked out depicted that T10- Removal and destruction of infected shoots and fruits was the best treatment recording higher benefit cost ratio (4.74).