Insect management and herbicide tolerance in near-isogenic sister lines of transgenic and non-transgenic sweet corn

Pest management systems were evaluated in three near-isogenic lines of transgenic and non-transgenic sweet corn. The genetic transformation was reputed to confer resistance to corn earworm (Helicoverpa zea) and European corn borer (Ostrinia nubilalis), and increase tolerance to the herbicide glufosinate. Plots were planted with either a transgenic line or a non-transgenic sister line. Transgenic and non-transgenic varieties were treated with a herbicide; either glufosinate or bentazon, respectively, applied post-emergence. Ears of the non-transgenic varieties were protected by spraying insecticides every 3-4 days. Transgenic varieties were not sprayed. Glufosinate caused temporary chlorosis (5% or less) and stunting (6% or less) of transgenic sweet corn in one experiment. Bentazon did not injure non-transgenic varieties. Corn earworm and European corn borer control in transgenic sweet corn was superior to that achieved in non-transgenic varieties sprayed with insecticides. Damaged ears of transgenic varieties ranged from 0% to 6% and most damage was restricted to the tip of the silk end. A few small, moribund larvae were recovered. In contrast, 40% of non-transgenic varieties, on average, had damaged ears, despite regular spraying of insecticides. Ears of non-transgenic varieties were damaged more severely and many late-instar larvae were recovered. (C) 2002 Elsevier Science Ltd. All rights reserved.