Lecanicillium saksenae: a novel nematophagous fungus against root knot nematode, Meloidogyne incognita (Kofoid & White, 1919) from Kerala, India

Identification of virulent nematophagous fungi is of great importance in biocontrol of plant parasitic nematodes. Lecanicillium saksenae is an indigenous isolate from Kerala, India with a high speed of kill against hemipteran pests. Nematophagous nature of the fungus unveiled in the preliminary studies prompted to evaluate its pathogenicity against root-knot nematode, Meloidogyne incognita. In vitro studies confirmed parasitism on nematode eggs eventually leading to its disintegration within 10 days. Bioefficacy studies carried out on eggs with partially purified hydrolytic enzymes revealed that the hatching was significantly reduced to 18.8 % with chitinase (100 μg/mL) and 10.4 % with protease (100 μg/mL) as against 70.80 % in absolute control. The combined application of protease and chitinase further decreased the egg hatching to 7.8 %. Scanning electron microscopy of the enzyme-treated eggs exhibited uneven and shrunken surfaces with distinct lines of breakage on the outer vitelline layer. Bioefficacy studies with the culture filtrate of L. saksenae on J₂ of M. incognita unveiled that the highest concentration (100 %), resulted in 100 % mortality after 96 h as compared to the control (12.5 %). In the egg hatching assay, the hatching per cent was only 3.25 at 120 h as against 76.25 per cent in control. The nematicidal potential of L. saksenae identified in this study would pave the way to the possibilities of tapping its potential as a biocontrol agent against M. incognita.