The presence and antifeedant function of toxin producing secretory cells on hyphae of the lawn-inhabiting agaric Conocybe lactea

On water agar, Conocybe lactea (Lange) Metrod produces droplets of toxin on conspicuous secretory cells. Both free-living rhabditoid nematodes and fungus-feeding nematodes (Aphelenchoides sp.) are immobilized when they contact the toxin droplets. Prolonged and (or) repeated exposure to the toxin results in death of the nematodes, which may take place at some distance from the contact point. Unlike Pleurotus ostreatus (Jacq.:Fr.) Kummer, the hyphae of C. lactea do not locate and colonize immobilized nematodes and (or) consume them as a nutrient source. It is considered that the toxin droplets are for protection of the hyphal system and function as antifeedants to repel or kill fungus-feeding nematodes and possibly other fungus-feeding soil microfauna. No differences were observed in nematode response between dikaryotic and monokaryotic cultures, although the latter produced a spermatial-like arthrosporic anamorph. Panaeolina foenisecii (Pers.:Fr.) R. Maire also produces secretory cells with fluid droplets. These droplets, however, are not as toxic to nematodes as those of C. lactea.