Distribution and toxigenicity of Aspergillus species isolated from maize kernels from three agro-ecological zones in Nigeria.
Aflatoxins are highly toxic cancer causing Aspergillus metabolites that cause immune-system suppression, growth retardation, cancer, and death in both humans and domestic animals. Aflatoxin-producing species have considerable intraspecific variability and the species that causes most aflatoxin contamination ofcrops, Aspergillusflavus, varies widely in aflatoxin production with some strains producing no aflatoxins. Biocontrol strategies to reduce aflatoxin contamination have been developed utilising strains ofAspergillusflavus, which do not produce aflatoxins to competitively exclude aflatoxin producers. In commercial practice, these atoxigenic strains are applied during crop development on a fungal food source that fuels initial reproduction and dispersal of the biocontrol agent. Although applications alter the composition ofAspergillusflavus communities associated with crops and, as a result, reduce crop aflatoxin content, both crop infection by Aspergillusflavus and the quantity ofAspergillusflavus on the crop at harvest are no different in treated and untreated crops. Long-term influences ofatoxigenic strain treatments have led to efforts to develop area-wide aflatoxin management programs. It is within such programs that the greatest potential for atoxigenic strain use may reside. However, for optimal benefits, improved methods for utilising atoxigenic strains must be envisioned and developed. It is likely these will include methods that simultaneously utilise multiple strains.