Current European corn borer, Ostrinia nubilalis, injury levels in the northeastern United States and the value of Bt field corn

Background: Recent evidence indicates that some populations of European corn borer (ECB), Ostrinia nubilalis (Hübner), have declined to historic lows owing to widespread adoption of Bt corn hybrids. To understand current ECB populations in Pennsylvania field corn, the authors assessed larval damage in Bt and non-Bt corn hybrids at 29 sites over 3 years. The influence of Bt adoption rates, land cover types and moth activity on levels of ECB damage was also considered. Results: Bt hybrids reduced ECB damage when compared with non-Bt, but these differences inconsistently translated to higher yields and, because of higher seed costs, rarely improved profits. No relationships were detected between land use or Bt adoption and ECB damage rates, but positive relationships were found between plant damage and captures of Z-race ECB moths in pheromone traps in the PestWatch network. Conclusions: ECB damage levels were generally low and appear to be declining across Pennsylvania. In many locations, farmers may gain greater profits by planting competitive non-Bt hybrids; however, Bt hybrids remain valuable control options, particularly in the parts of Pennsylvania where ECB populations persist. Moth captures from PestWatch appear to provide insight into where Bt hybrids are most valuable.