Department of Entomology, Iowa State University, Ames, IA, United States of America.
Bayer Crop Science, Resistance Management, Chesterfield, MO, United States of America.
PLoS One. 2020 Jul 31;15(7):e0237094. doi: 10.1371/journal.pone.0237094. eCollection 2020.
Western corn rootworm, Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is a major pest of corn in the United States. Transgenic corn expressing insecticidal proteins derived from the bacterium Bacillus thuringiensis (Bt) is an important tool used to manage rootworm populations. However, field-evolved resistance to Bt threatens this technology. In areas where resistance is present, resistant individuals may travel from one field to a neighboring field, spreading resistance alleles. An important question that remains to be answered is the extent to which greater-than-expected root injury (i.e., >1 node of injury) to Cry3Bb1 corn from western corn rootworm is associated with rootworm abundance, root injury, and levels of resistance in neighboring fields. To address this question, fields with a history of greater-than-expected injury to Cry3Bb1 corn (focal fields) and surrounding fields (< 2.2 km from focal fields) were examined to quantify rootworm abundance, root injury, and resistance to Cry3Bb1 corn. Additionally, use of Bt corn and soil insecticide use for the previous six years were quantified for each field. Resistance to Cry3Bb1 was present in all fields assayed, even though focal fields had grown more Cry3 corn and less non-Bt corn than surrounding fields. This finding implies that some movement of resistance alleles had occurred between focal fields and surrounding fields. Overall, our data suggest that resistance to Cry3Bb1 in the landscape has been influenced by both local rootworm movement and field-level management tactics.
西方玉米根萤叶甲，Diabrotica virgifera virgifera LeConte（鞘翅目：叶甲科），是美国玉米的主要害虫。表达来自苏云金芽孢杆菌（Bt）的杀虫蛋白的转基因玉米是管理根萤叶甲种群的重要工具。然而，田间进化的抗药性对这项技术构成了威胁。在存在抗性的地区，抗性个体可能从一个田地传播到邻近的田地，传播抗性等位基因。一个仍然需要回答的重要问题是，来自西方玉米根萤叶甲的 Cry3Bb1 玉米遭受的超出预期的根损伤（即，>1 个节点的损伤）与根萤叶甲丰度、根损伤和邻近田地的抗性水平之间的关联程度。为了解决这个问题，对具有 Cry3Bb1 玉米遭受超出预期损伤史的田地（焦点田地）和周围田地（距离焦点田地<2.2 公里）进行了检查，以量化根萤叶甲丰度、根损伤和对 Cry3Bb1 玉米的抗性。此外，还对每个田地过去六年中使用 Bt 玉米和土壤杀虫剂的情况进行了量化。尽管焦点田地种植的 Cry3 玉米更多，而非 Bt 玉米更少，但所有检测的田地都存在对 Cry3Bb1 的抗性。这一发现表明，抗性等位基因已经在焦点田地和周围田地之间发生了一些转移。总的来说，我们的数据表明，景观中的 Cry3Bb1 抗性受到了根萤叶甲的局部迁移和田间管理策略的共同影响。
