Corn Borer's Comeback - Resistance Threatens Bt Technology

By Scout Nelson

The European corn borer (ECB), an agricultural pest that has historically caused significant damage to corn crops in the United States. It discusses the identification of ECB, its introduction to the U.S., and the success of using Bacillus thuringiensis (Bt) technology in managing infestations. However, the emergence of field-evolved resistance to Bt proteins in Canadian populations raises concerns about the potential spread of resistant strains to the U.S. Corn Belt.

The proximity of Canada to the U.S. Corn Belt and the role of environmental factors, such as wind, in dispersing resistant strains highlight the need for proactive monitoring and resistance management strategies. The article emphasizes the importance of the high dose/refuge strategy, which involves planting a refuge of non-Bt crops to maintain susceptible populations and delay resistance development. Additionally, the adoption of multi-Bt proteins (Bt pyramids) in corn hybrids is recommended for effective resistance management.

The researchers stress the significance of ongoing resistance monitoring efforts, particularly in the face of reported cases of resistance in Canada and the U.S. The University of Minnesota's Department of Entomology is actively conducting surveys to assess susceptibility levels and Bt resistance allele frequencies in ECB populations. Farmers encountering ECB infestations are encouraged to reach out for assistance in determining Bt resistance levels.

Integrated pest management (IPM) approaches are also recommended, including cultural practices that support beneficial arthropods and reduce larval densities within fields. Techniques such as plowing corn plant residue and shredding corn stalks can contribute to preventing the establishment of resistant ECB populations.

The European corn borer and the importance of a comprehensive and proactive approach to resistance management to preserve the effectiveness of Bt technology in controlling this agricultural pest.

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