The Insect-parasitic Stage and Life Cycle of Iotonchium ungulatum (Tylenchida: Iotonchiidae), the Causal Agent of Gill-knot Disease of the Oyster Mushroom

Abstract

Iotonchium ungulatum is the causal agent of gill-knot disease of the oyster mushroom, Pleurotus ostreatus. The insect-parasitic females of this nematode are described. The insect-parasitic female nematodes inhabit and lay many eggs in the haemocoel of the fungus gnat, Rhymosia domestica. Juvenile nematodes hatched from these eggs invade host gnats ovaries, and the nematodes are supposed to be deposited on the gills of the oyster mushroom where they generate knots and grow into the mycetophagous females. In the laboratory experiment, female gnats harbored significantly greater number of insect-parasitic female nematodes than did the male gnats. Jpn. J. Nematol. 30 (1/2): 1-7 (2000).