Protective formula and preservation conditions for the endoparasitic fungus, Esteya vermicola

Abstract

The endoparasitic nematophagous fungus, Esteya vermicola, is a bio-control agent with demonstrated ability to attack pinewood nematode (Bursaphelenchus xylophilus). An optimized solution for the protection and preservation of E. vermicola conidia is needed in order to ensure their survival during transportation, preservation, and application. Five protectants, kaolin, arabinose, sorbitol, PEG8000, and Span 80, were selected from 34 agents. These were incorporated into calcium alginate gel capsules at the following concentrations: 10% kaolin, 0.1% Span 80, 1% arabinose, 5% sorbitol, and 5% PEG8000. The improved diffluent formula contained 69.9% soluble starch, 14% wheat flour, 5% PEG8000, 0.1% span 80, 1% arabinose and 10% skim milk. The viability of E. vermicola conidia preserved in the protectant (5% sorbitol and 20% PEG8000) at six temperatures,–70,–20, 4, 26, 37°C, and room temperature (uncontrolled), was also assessed. The highest viability after storage for one month was achieved at–70°C.