Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of maize in the United States and is an invasive pest in Europe. Maize is the only agricultural crop on which western corn rootworm larvae can survive and this insect requires two consecutive years of maize cultivation to complete its life cycle. Transgenic maize producing insecticidal proteins derived from the bacterium Bacillus thuringiensis (Bt) is often used to manage rootworm populations. The first Bt trait, Cry3Bb1, was introduced in 2003, but larval resistance to this toxin appeared in northeastern Iowa in 2009. Rootworm management occurs on a field-by-field basis, but adult rootworm may disperse among fields. It is known that growing consecutive years of Cry3Bb1 maize within a field can lead to resistance, but the relationship of the surrounding landscape to the development of resistance is unknown. Using geospatial tools and publicly available land-use data, we examined circular areas (buffers) surrounding fields that had previously experienced high levels of rootworm injury to Cry3Bb1 maize and rootworm resistance to Cry3Bb1 maize (problem fields). We calculated the proportion of area inside each buffer planted to maize continuously for 1–9 yr, and compared these values to those for randomly selected control points throughout the state. We also calculated the proportion of the state planted to maize for at least three consecutive years for 2003 through 2018, and its relationship with the annual value of maize. We found that areas surrounding problem fields had significantly more continuous maize compared to controls, with the most continuous maize within 1.6 km of problem fields. We also found that the cultivation of continuous maize in Iowa increased significantly between 2003 and 2018, and this was correlated with average annual price of maize. We hypothesize a scenario in which continuous cultivation of Cry3Bb1 maize in local landscapes, driven in part by the increased value of maize, facilitated selection for Cry3Bb1 resistance. These results suggest that land use in areas surrounding problem fields affect the rate of resistance evolution and approaches for resistance management can be enhanced by taking a landscape-level perspective.

中文翻译：

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将 Bt 玉米的土地利用模式与病虫害爆发联系起来

西部玉米根虫Diabrotica virgifera virgifera LeConte（鞘翅目：Chrysomelidae）是美国玉米的主要害虫，在欧洲是入侵性害虫。玉米是西部玉米根虫幼虫唯一可以生存的农作物，这种昆虫需要连续两年的玉米栽培才能完成其生命周期。产生源自苏云金芽孢杆菌细菌的杀虫蛋白的转基因玉米(Bt) 通常用于管理根虫种群。第一个 Bt 性状 Cry3Bb1 于 2003 年引入，但幼虫对这种毒素的抗性于 2009 年在爱荷华州东北部出现。根虫管理是逐个田地进行的，但成年根虫可能会在田间分散。众所周知，在一个田地内连续多年种植 Cry3Bb1 玉米会导致抗性，但周围景观与抗性发展的关系尚不清楚。使用地理空间工具和公开可用的土地利用数据，我们检查了先前经历过对 Cry3Bb1 玉米的根虫高度损伤和根虫对 Cry3Bb1 玉米（问题田地）的抗性的田地周围的圆形区域（缓冲区）。我们计算了连续种植玉米 1-9 年的每个缓冲区内的面积比例，并将这些值与全州随机选择的控制点的值进行比较。我们还计算了 2003 年至 2018 年至少连续三年的国家种植玉米的比例，及其与玉米年产值的关系。我们发现，与对照相比，问题田周围区域的连续玉米明显更多，问题田周围 1.6 公里范围内的玉米最连续。我们还发现，2003 年至 2018 年爱荷华州连续种植玉米的种植量显着增加，这与玉米的年均价格相关。我们假设一种情景，在当地景观中连续种植 Cry3Bb1 玉米，部分原因是玉米价值增加，促进了 Cry3Bb1 抗性的选择。