Mitigation and management of Cry1F resistance in European corn borer in Canada

欧洲玉米螟（ECB;欧洲玉米螟（Ostrinia nubilalis）自世纪初首次被发现以来，一直是整个北美玉米的经济害虫。ECB在玉米中的取食伤害导致产量损失、穗脱落、茎断裂和倒伏，从而阻碍收获。在引入转基因玉米（表达来自苏云金芽孢杆菌（Bt玉米）的杀虫蛋白）之前，估计整个北美的ECB管理和发生的产量损失超过13亿加元。自1996年首次引入以来，Bt玉米已被广泛用于ECB管理，2017年，加拿大85%的玉米英亩种植了Bt玉米。对Bt蛋白的抗性发展是Bt玉米可持续利用的主要威胁;然而，ECB在北美密集使用20多年后仍然对Bt毒素敏感。 2018年，我们的研究团队在加拿大新斯科舍省的ECB内发现了北美第一例实际田间进化的Bt玉米抗性。ECB对Bt蛋白的抗性的发展对Bt玉米在北美的持续成功具有广泛的影响。拟议研究的主要目标是减轻加拿大ECB的Cry 1F抗性。为了实现这一目标，关键是要了解加拿大东部ECB的物候，表征在NS中发现的Cry 1F抗性，确定Cry 1F抗性种群的当前分布，以及加拿大ECB对剩余Bt蛋白的敏感性，以实现可持续管理。这种情况也提供了一个机会，以评估行业主导的战略，以减轻Cry 1F抗性，取代单事件Bt玉米杂交种与ECB控制的产品。最后，这一事件提供了一个机会，以评估目前的抗虫监测（Bt玉米在加拿大）策略的有效性，并探讨潜在的方法，以提高抗虫监测使用分子技术。

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.