Submitted to: Aflatoxin Elimination Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: November 20, 1999
Publication Date: N/A
Technical Abstract: The relationship between insect damage and aflatoxin contamination of corn grain has been examined by several researchers. Because injuries resulting from insect feeding on ears of corn provide potential sites for fungal invasion, resistance to insect damage should be effective in reducing fungal infection and subsequent aflatoxin accumulation. Development of transgenic corn plants expressing insecticidal proteins isolated from the bacterium Bacillus thuringiensis (Bt) has provided a new and potentially useful source of resistance to Lepidoptera. The current investigation was undertaken to compare the damage sustained by transgenic and conventional commercial corn hybrids infested with southwestern corn borer, Diatraea grandiosella, larvae when plants were in the whorl stage of growth or 14 to 21 days after anthesis and to compare aflatoxin accumulation among hybrids following infestation. In addition to infestation with insects, the top ears of all plants were sprayed weekly for 5 weeks with an Aspergillus flavus spore suspension beginning approximately 7 days after silk emergence. Ears were harvested approximately 63 days after midsilk, rated for insect damage, and shelled. The grain was ground and aflatoxin level determined. The transgenic corn hybrids sustained very little leaf feeding damage when infested in the whorl stage of growth with southwestern corn borer larvae and very little ear damage when infested at either stage of growth. The conventional hybrids sustained significant leaf and ear damage. The highest levels of aflatoxin were observed in the nontransgenic hybrids infested with southwestern corn borer after anthesis.