Comparative vulnerability of Helicoverpa armigera (Hubner) larvae to selected entomopathogenic fungi

Abstract

The larvae of Helicoverpa armigera (Hubner), (Lepidoptera: Noctuidae), a polyphagous pest affecting different crops in India, were treated with variable concentrations of conidia of two soil isolates and two commercially available entomopathogenic fungi belonging to two species, Beauveria bassiana (Balsamo-Crivelli) Vuillemin and Metarhizium anisopliae (Metschnikoff) in a laboratory. The suspension of conidia (109 conidia/ml) collected from Sabouraud dextrose agar media with yeast extract (SDAY) plates resulted in the highest mortality (98.3%) with Beauveria bassiana (PSC-13) and the lower mortality (75%) with Metarhizium anisopliae (Ag-CM). Using the larval immersion method, the values of LC50 and LC90 reveal that Beauveria bassiana was the most virulent species while Metarhizium anisopliae was the less virulent species in between the entomopathogenic fungi used in bioassay. The local strain of Beauveria bassiana (PSC-13) and Metarhizium anisopliae (PSC-11) was more virulent than the tested commercial strain.