Aflatoxin accumulation in conventional and transgenic corn hybrids infested with southwestern corn borer (Lepidoptera : Crambidae)

摘要

Aflatoxin is a potent carcinogen produced by the fungus Aspergillus flavus Link:fr. 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, Diatraea grandiosella Dyar, damage on aflatoxin contamination were investigated. Aflatoxin contamination levels in conventional nonBt corn hybrids and transgenic Bt hybrids after 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, yield loss, and aflatoxin contamination. Losses were significantly reduced in transgenic Bt hybrids.