ELECTRON-MICROSCOPY OF 2 NEMATODE-DESTROYING FUNGI, MERISTACRUM-ASTEROSPERMUM AND ZYGNEMOMYCES-ECHINULATUS (MERISTACRACEAE, ENTOMOPHTHORALES)

Infection of nematodes by Meristacrum asterospermum and Zygnemomyces e chinulatus was initiated by conidia adhering to the nematode's cuticle . Each conidium developed an infection peg to penetrate the nematode a fter adhesion. In M. asterospermum, an infection peg just under the pe netration was found in ultrathin sections, in which the peg's cell wal l was broken into several lobes that were covered entirely with an amo rphous mass of electron-opaque substance. Septa formed in the apical p ortion of aerial conidiophore under conidiation. The septal wall was n onperforate and often contained electron-opaque inclusions. Vegetative hyphae of Z. echinulatus had typical bifurcate septa, but septa at bo th ends of the pedicel of conidia were often slightly deformed.