Effects of Resinous Compounds from Pine Trees on Spore Germination and Mycelial Growth of a Nematophagous Fungus, <i>Esteya vermicola</i>

Pine wilt disease caused by pine wood nematodes (PWN) have been reported to give severe damage in many countries worldwide. Many measures of PWN management have been implemented, including using the nematophagous fungus <i>Esteya vermicola</i> as a biological control agent. However, understanding on the interaction between this fungus and pine trees is still limited. This study aimed to evaluate the effects of resinous compounds on spore germination and mycelial growth of <i>E. vermicola in vitro</i>. Research results showed that resinous compounds from pine trees significantly affect spore germination and mycelial growth of <i>E. vermicola</i>. In which, (+)α-pinene, (-)α-pinene, and (-)limonene completely inhibited spore germination and mycelial growth, with 100% of spore germination inhibition rate (SGIR) and mycelial growth inhibition rate (MGIR). The mixture of 14 resinous compounds also indicated potent inhibition of spore germination and mycelial growth of <i>E. vermicola</i>, with 100% and 91.8% SGIR and MGIR, respectively. These results suggest that trunk injection of spore suspension of <i>E. vermicola</i> to pine tree could be unsuccessful and ineffective for the control of pine wilt disease.