Host deception: predaceous fungus, Esteya vermicola, entices pine wood nematode by mimicking the scent of pine tree for nutrient.

Abstract

A nematophagous fungus, Esteya vermicola, is recorded as the first endoparasitic fungus of pine wood nematode (PWN), Bursaphelenchus xylophilus, in last century. E. vermicola exhibited high infectivity toward PWN in the laboratory conditions and conidia spraying of this fungus on Japanese red pine, Pinus densiflora, seedlings in the field protected the pine trees from pine wilt disease to some extent, indicating that it is a potential bio-control agent against PWN. Previous research had demonstrated that the living fungal mycelia of E. vermicola continuously produced certain volatile organic compounds (VOCs), which were responsible for the PWN attraction. However, identity of these VOCs remains unknown.In this study, we report the identification of α-pinene, β-pinene, and camphor produced by living mycelia of E. vermicola, the same volatile compounds emitted from PWN host pine tree, as the major VOCs for PWN attraction using gas chromatography-mass spectrometry (GC-MS). In addition, we also confirmed the host deception behavior of E. vermicola to PWN by using synthetic VOCs in a straightforward laboratory bioassay.This research result has demonstrated that the endoparasitic nematophagous fungus, E. vermicola, mimics the scent of PWN host pine tree to entice PWN for the nutrient. The identification of the attractive VOCs emitted from the fungus E. vermicola is of significance in better understanding parasitic mechanism of the fungus and the co-evolution in the two organisms and will aid management of the pine wilt disease.