Submitted to: Journal of Agricultural and Urban Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2003
Publication Date: 7/1/2003
Citation: Williams, W.P., Windham, G.L., Buckley, P.M., Daves, C. 2003. Aflatoxin accumulation in conventional and transgenic corn hybrids infested with southwestern corn borer (Lepidoptera: Crambidae). Journal of Agricultural and Urban Entomology 19:227-236. Interpretive Summary: Aflatoxin contamination of corn greatly reduces the value and marketability of corn. Aflatoxin, which is produced by the fungus Aspergillus flavus, is toxic to livestock and causes cancer in humans. Aflatoxin contamination is frequently linked with drought, high temperatures, and insect damage and is a major impediment to profitable corn production in the South. In this investigation, aflatoxin contamination levels of conventional nonBt corn hybrids and transgenic Bt corn hybrids were compared following inoculation with an A. flavus spore suspension using both kernel-wounding and nonwounding techniques and infestation with southwestern corn borer larvae. Aflatoxin contamination was highest in both Bt and nonBt hybrids when kernels were mechanically injured during inoculation. When kernels were not mechanically wounded during inoculation, aflatoxin contamination was significantly lower in Bt hybrids. Infestation with southwestern corn borer resulted in a significant increase in aflatoxin of the nonBt hybrids, but not the Bt hybrids. The results of this investigation indicate that the resistance to southwestern corn borer provided by transgenic Bt corn hybrids could be useful in reducing aflatoxin contamination in areas where southwestern corn borers are present.
Technical Abstract: Aflatoxin is a potent carcinogen that is produced by the fungus Aspergillus flavus. Aflatoxin contamination of corn greatly diminishes its value and is a major impediment to profitable corn production in the South. Aflatoxin contamination is frequently linked with drought, high temperatures, and insect damage. The effects of southwestern corn borer damage on Aflatoxin contamination were investigated. Aflatoxin contamination levels in conventional nonBt corn hybrids and transgenic Bt hybrids following inoculation with A. flavus and infestation with southwestern corn borer were compared. Aflatoxin contamination was highest when hybrids were inoculated with A. flavus using a technique that wounded the kernels. Aflatoxin contamination was significantly greater in nonBt than in Bt hybrids when ears were inoculated by spraying with an A. flavus conidial suspension and concurrently infesting with southwestern corn borer. Infesting conventional nonBt hybrids with southwestern corn borer resulted in significant leaf feeding, stalk tunneling, stunting, yields loss, and Aflatoxin contamination. Losses were significantly reduced in transgenic Bt hybrids.