NEMATOCIDAL METABOLITES FROM HIGHER FUNGI

The adverse effects on human health and well being and the high econom ic losses inflicted by pathogenic nematodes are important stimulants f or the search of new, safe and effective nematicides and anthelminthic s. The pool of natural products is an important source for such compou nds, and several of the most potent nematicides used today originate f rom streptomycetes. Higher fungi have an extensive secondary metabolis m at their disposal, and obviously some benefit from the capability to kill nematodes. Surprisingly little is known about the production of nematicidal metabolites by fungi. Examples of compounds isolated from ascomycetes are the cochlioquinones and the mycorrhizins, which are st rongly active against the saprophytic Caenorhabditis elegans but not t owards the economically important plant pathogen Meloidogyne incognita . From basidiomycetes, the cyclic dodecapeptide omphalotin was obtaine d which seems to be highly selective for M. incognita. Compounds with good activity against a abomasum nematode in vivo are the macrodiolide s clonostachydiol and helminidiol. When screening for nematicidal acti vity, it is important to use the proper test system as the sensitivity of different nematodes may vary considerably. Consequently, the searc h for agents active against M. incognita may be futile, if saprophytic nematodes are used as test organisms. The importance to develop relev ant screening systems that are easy to use and have an acceptable capa city is therefore emphasized.