Microsclerotia formation of the biocontrol fungus Cordyceps javanica IF-1106 and evaluation of its stress tolerance and pathogenicity

Spores germinate quickly, and hyphal elements clump together, forming hydrophobic microsclerotia. The microsclerotia have 100% survival under 55°C and UV-B radiation of 3 J cm^-2. Following such exposure, the microsclerotia are able to germinate and produce conidia. After 1 year of storage at either room temperature (25°C) or refrigeration (-80°C, -20°C, and 4°C), all the microsclerotia germinated and spore yield was more than 4 × 10⁹ spores g^-1. Finally, <i>C. javanica</i> IF-1106 microsclerotia showed ovicidal activity against root-knot nematode eggs, and a glasshouse pot trial indicated that control efficiency of microsclerotia against root-knot nematodes reached 92.6%, which improved the growth of the test cucumber plants. These attributes suggest that microsclerotia of this fungus can be applied as a biocontrol agent to control soil borne pest nematodes.