Effects of mineral salts on the growth, sporulation and virulence of Esteya vermicola, an endoparasitic fungus of the pinewood nematode, Bursaphelenchus xylophilus

Esteya vermicola, an endoparasitic fungus of pinewood nematode, exhibits great potential as a biological agent against nematodes. In this study, various mineral supplements, such as chloride salts (KCl, CaCl2, MgCl2, FeCl2, and FeCl3) and calcium salts (CaCl2, CaCO3, and CaSO4) were evaluated for their ability to enhance the growth, sporulation and virulence of E. vermicola. Of the cations tested, CaCl2 provided the greatest enhancement of growth speed and sporulation. Of the anions tested, CaCO3 produced the highest proportion of lunate conidia, and CaCl2 produced the highest adhesive rate and mortality against the nematode, Bursaphelenchus xylophilus. The optimum concentration of CaCl2 for optimization of sporulation and virulence was 0.4-0.6%. In conclusion, CaCl2 is highly effective in enhancing growth, sporulation and virulence of Esteya vermicola.