Characterization of the <e1>Aspergillus flavus</e1> population within an Illinois maize field (D. T. Wicklow, C. E. McAlpin and C. E. Platis)

An evaluation was made of the genotypic diversity (DNA fingerprinting) of 269 <e1>A. flavus</e1> strains, including subpopulations isolated from grain sampled at harvest (91 unique ‘fingerprints’ or genotypes/128 strains), field soil (26 genotypes/31 strains), maize insects (49 genotypes/52 strains) and air-spora (56 genotypes/58 strains), from a maize field near Kilbourne, Illinois. Eight <e1>A. flavus</e1> genotypes were isolated from grain samples harvested in different years (1988–1991). Genotype 36, isolated from three maize samples, matched the DNA fingerprint of a K. E. Papa strain NRRL 19997, isolated from maize grown in Georgia. Ninety-eight percent of the <e1>A. flavus</e1> genotypes produced sclerotia and 53% produced aflatoxin. Contrasts of DNA fingerprints revealed two matches involving subpopulations from grain and soil, one match for grain and maize insects, and no matches for grain and air-spora. The high genotypic diversity recorded for each subpopulation, in addition to a limited sample size, precluded any assessment of the relative importance of these subpopulations as sources of <e1>A. flavus</e1> infective inoculum. <e1>Aspergillus parasiticus</e1> was routinely isolated from soil samples.