Collection, characterization and screening of entomopathogenic fungi against fieldbean pod borer (Helicoverpa armigera, Hubner)

An attempt was made to identify, evaluate and standardize entomopathogenic fungi for control of Helicoverpa armigera. During survey for field bean pod borer incidence, 7 fungal infected larvae were collected and as many as seven fungal isolates were isolated form dead and infected larvae. Based on colony and conidial morphology, all fungal isolates were characterized up to genus level as Penicillium sp, Asperigillus sp., Metarhizium sp., Nomuraea sp., and Beauveria sp. All fungal isolates were screened against III instar level of H. armigera to assess their pathogenicity. Beauveria sp. showed infection resulting in highest per cent mortality to the tune of 60.50%. Lower lethal time of 7.47 days was observed at 10⁸ spore concentration/ml followed by 10⁷ spore concentration/ml (8.26 days) and the maximum medium lethal time (LT₅₀) of 3 22.15 days was observed at 10³ spore concentration/ml. Similarly, low LT₉₉ values of 10.75 days were observed at 10⁸ spore concentration/ml followed by 10⁷ spore concentration/ml indicating the mean lethal time decrease with increase in concentration of spores per ml.