Pathogenicity of Beauveria bassiana (Balsamo) Vuillemin Isolate (TNAU ENT BB1) Against Rice Leaf Folder, Cnaphalocrocis medinalis (Guenee) in In-vitro (Laboratory) Conditions

Rice productivity is impaired by sucking, leaf feeding and borer insect pests. Among the leaf feeders, rice leaf folder Cnaphalocrocis medinalis (Guenee) cause significant yield loss. The non-chemical insect pest management is gaining momentum among farmers, and biocontrol management is one of the essential components. The efficacy of entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin isolate against C. medinalis was studied using the laboratory culture maintained in rice leaves. Different concentrations of B. bassiana were applied topically on the second instar C. medinalis larvae. The mortality observations were recorded at 48 hrs intervals from the third day and continued up to 11 days. The highest mortality of 78.33% was observed at concentration 1×108 conidia/ml, and the lowest mortality of 36.67% was observed at concentration 1×103 conidia/ml. The determined median lethal concentration (LC50) of B. bassiana (Balsamo) Vuillemin isolate against C. medinalis is 5.44 x 105 conidia/ml.