Submitted to: Mycological Symposium Asian Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 5, 1996
Publication Date: N/A
Technical Abstract: The fungi that colonize corn ears and may contaminate the grain with mycotoxins include pathogens, endophytes and opportunists that belong to ecologically specialized groups. These include seed replacement diseases, mildly parasitic colonists of the phylloplane, stem-rot and ear-rot pathogen complex, 'protective' endophyte mutualists, saprotrophs and yeasts in ears damaged by corn insects or birds. Aspergillus flavus, which is also pathogenic to insects, is included in this latter group. Sap beetles (Nitidulidae) are common vectors of toxigenic fungi, moving from crop residues or nearby natural habitats, to ripening corn ears. The fungi initially become established in grains damaged by corn insects then spread to infect the undamaged grains. Ecological studies of the chemistry of sap beetle interactions with fungi are helping to explain the attractiveness of selected fungi to sap beetles while also guiding the discovery of novel fungal metabolites with potent antiinsectan activity. Competitive interactions and mycoparasitism can impact the pathogenicity and survival of toxigenic fungi. Fusarium moniliforme limits the spread of A. flavus from sites of wound-inoculation. Paecilomyces lilacinus and other mycoparasites colonize and kill A. flavus sclerotia buried in corn field soil. Intraspecific competition among naturally occurring aflatoxin-producing and non-aflatoxin producing A. flavus strains (@ 50%) may serve to 'dampen' aflatoxin outbreaks in the midwest Corn Belt.