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Section Symposium

Plant-Insect Ecosystems

Plant-Insect Ecosystems

Leading with Passion and Innovation: Perspectives from Those Shaping the History of Transgenic Crops

Frequency of molecular markers linked to Cry1F resistance in European corn borer from the USA

Sunday, November 9, 2025
9:10 AM - 9:25 AM Pacific
Location: Oregon Convention Center, D135, OCC
Oral Presentation
Bacillus thuringiensis (Bt) corn is genetically engineered to produce proteins that have toxic and insecticidal characteristics towards specific insect pests. However, insects are rapidly evolving resistance to Bt crops, including European corn borer (ECB, Ostrinia nubilalis). The first case of practical resistance to Bt corn by ECB was documented in 2018 in Nova Scotia, Canada. DNA mutations in ABC transporter genes have been linked to Bt resistance in many species. In ECB, six molecular markers (i.e. single nucleotide polymorphism, or SNPs) associated with resistance have been identified within the ABCC2 gene. Most of these SNPs cause nonsynonymous changes in the amino acid sequence, but one marker, SNP5, causes a two-base pair deletion, frameshift, and a premature stop leading to significant changes in the protein structure. We generated SNP genotypes from 364 ECB individuals collected across the USA in 2022 and 2023. The frequency of resistance-linked alleles was compared across all sites, and at three sites with multiple collections over 2 years. We found high frequencies of resistance-linked alleles, ranging from 50% to 100% across the study site and SNPs. For SNP5, which may be the most important SNP, the resistant-linked allele was only found in 2023 samples and at a total frequency of 0.5% across all locations. The data suggest that the low frequency of resistant SNP5 is consistent with a lack of Cry1F field failures reported in the USA. This study provides data that will help further understand the evolution of Bt resistance in ECB.