DNA-based detection of field-evolved Cry1F resistance in the European corn borer (Ostrinia nubilalis)

Ostrinia nubilalis Hübner (Lepidoptera: Crambidae) is an economic pest of over 200 host crops, including corn Zea mays(L.), in Canada, United States, and Europe. Annual costs of management and yield loss were estimated to exceed $1 billon USD in the US alone, before the introduction of transgenic corn expressing insecticidal proteins from Bacillus thuringiensis (Bt corn). The commercialization of Bt corn targeting O. nubilalis directly resulted in reduced management costs and yield losses across North America, with >20 years of success. However, in 2018, the first case of practical field-evolved resistance to Bt corn expressing Cry1F by O. nubilalis was discovered in Nova Scotia, Canada. Studies on laboratory derived Cry1F resistant O. nubilalis linked Cry1F resistance with ATP Binding Cassette subfamily C2 (ABCC2) gene. In this work, we report on mutations in ABCC2 gene as linked to field resistance to Cry1F protein in O. nubilalis. Additionally, we describe a DNA-based Cry1F resistance genotyping test to demonstrate the presence of the resistant allele in O. nubilalis populations collected in Canada. These DNA-based screening data provide strong evidence that Cry1F resistance in O. nubilalis maps to the ABCC2 gene and provides a useful molecular marker for detecting the Cry1F resistance allele in O. nubilalis. Additional work is required to determine the causal mutations resulting in Cry1F resistance.