Infection events in the fungus-nematode system

Infection of vermiform nematodes by nematophagous fungi generally follows the same route whether the nematode is captured in adhesive traps of predatory fungi or mediated by conidia of endoparasites. A successful infection always results in complete digestion of the nematode corpus. The total time for the infection process varies between fungal species and also between species of nematodes being parasitized. The zoosporic phycomycete Catenaria anguillulae usually completes its life cycle in a rhabditoid nematode in 24 hr, whereas the hyphomycetous endoparasite Meria (Drechmeria) coniospora takes up to 72 hr for the same process. The infection of nematodes by nematophagous fungi usually follows a general sequence of events starting with recognition between the two types of organisms. We will use the term recognition in a broad sense including attraction phenomena as well as interactions on a molecular level involved in adhesion.1-2 The recognition step is followed by penetration of the nematode cuticle, possibly a toxification step, and finally the animal is digested by trophic hyphae of the fungus. The different infection events, some of which may not necessarily be present in all fungal-nematode interactions, will be discussed in this chapter