Aflatoxin Contamination of Corn Before Harvest: Aspergillus flavus Association with Insects Collected from Developing Ears

The study examined the relationship of AspergUlus flavus Link ex Fr. in insects collected from developing ears and aflatoxin contamination of the kernels of com (Zea mays L.). In 1976 two hybrids adapted for growth in the South and two hybrids adapted to the Com Belt were grown at 11 diverse locations in the USA. Planting and harvest dates were staggered to examine maturity factors. Of 1621 insect larvae collected, A. flavus was identified on 54 specimens (3.3%). The distribution of A. flavus on the insects was relatively uniform between test locations and across maturity groups and hybrids. However, common occurrence of aflatoxin was restricted to corn grown in the South, particularly in hybrids not adapted to the region. A detailed study of Georgia·grown corn demonstrated that aflatoxin was not present in ker· nels 20 days post.flowering, but the toxin was routinely found in samples collected 40 days after flowering. The results show a broad geographical occurrence of A. flavus on insects feeding on developing com but a distinct in· terregional difference in the contamination of the grain by aflatoxin.