B.L. TANDI

Effectiveness of entomopathogenic fungus, Nomuraea rileyi was tested against II and IV instar larvae of Helicoverpa armigera on chickpea by two methods of application i.e. leaf dip and leaf spray under laboratory conditions. It caused 85 per cent mortality of II instar larvae within 5 days and 75 per cent mortality of IV instar larvae within 10 days, when applied at 5×108 conidia/ml to chickpea leaves by dipping method of application. The LD50 values of fungus computed for II instar larvae were 8.06×106 conidia/ml with dip method and 2.42 × 107 conidia/ml with spray method, 4 days after the treatment. However, 3 to 4 times more conidial suspension (2.68×107 and 1.09×108) of the fungus is required to kill 50 per cent population of IV instar larvae, after 7 days of treatment. The LT50 of II instar larvae with the dose of 5×106 conidia/ ml were 4.38 and 5.42 days with dip and spray methods, respectively. However, LT50 of IV instar larvae with dip and spray methods with the dose of 5×107 conidia/ml were 7.18 and 8.84 days, respectively.