Integration of biological control and transgenic insect protection for mitigation of mycotoxins in corn

Biological control is known to be effective in reducing aflatoxin contamination of corn, and some transgenic corn hybrids incur reduced damage from corn earworm (Helicoverpa zea) than comparable non-Bt hybrids. We conducted seven field trials over two years to test the hypothesis that transgenic insect protection and biological control could be integrated to prevent mycotoxin contamination of corn. Corn hybrid N78N3111, expressing the highest degree of transgenic insect protection, was nearly 100 percent free from corn earworm damage and generally had less than half as much contamination from fumonisin compared to N78NGT, a near isogenic corn hybrid without insect protection. This insect protection, however, did not significantly prevent aflatoxin contamination. Soil application of non-aflatoxigenic biocontrol strains of Aspergillus flavus significantly reduced aflatoxin concentrations in corn. Biocontrol strain 21882 of A. flavus was especially effective and reduced aflatoxin contamination by about 90 percent over the seven field trials. There was no significant interaction between the insect protection and biocontrol treatments. Although no synergies were detected, the reduction of mycotoxins by both strategies supports application of both strategies in tandem. Economic factors external to the cost of the technologies will be a major determinant if the mycotoxin mitigation attained by use of these technologies will have a positive economic benefit.