Grant: Alliance Grants

European corn borer (ECB; Ostrinia nubilalis) has been an economic pest of corn throughout North America since its first detection in the early 20th century. Feeding injury by ECB in corn results in yield loss, ear drop, stalk breakage, and lodging, impeding harvest. Management of ECB and incurred yield losses were estimated to exceed $1.3 billion CAD across North America before the introduction of genetically modified corn that expresses insecticidal proteins from the bacterium Bacillus thuringiensis (Bt corn). Since its first introduction in 1996, Bt corn has been widely adopted for ECB management and in 2017, 85% of corn acres in Canada were planted with Bt corn. Resistance development to Bt proteins is a major threat to the sustainable use of Bt corn; however, ECB remained susceptible to Bt toxins after more than 20 years of intensive use in North America. In 2018, our research team discovered the first case of practical field-evolved resistance to Bt corn in North America within ECB in Nova Scotia, Canada. The development of resistance to Bt protein by ECB has wide-ranging implications for the continued success of Bt corn in North America. The principal objective of the proposed research is to mitigate Cry1F resistance in ECB in Canada. To achieve this, it is critical to understand the phenology of ECB in Eastern Canada, characterize the Cry1F resistance discovered in NS, determine the current distribution of Cry1F-resistant populations, and the susceptibility of ECB in Canada to remaining Bt proteins for sustainable management. This situation also provides an opportunity to evaluate the industry-led strategy to mitigate Cry1F resistance by replacing single event Bt corn hybrids with pyramided products for ECB control. Lastly, this occurrence provides an opportunity to evaluate the efficacy of current insect resistance monitoring (IRM) strategies for Bt corn in Canada and to investigate potential ways to improve IRM using molecular techniques.