Abstract A seed blend refuge has been used to host susceptible insects for Bt maize insect resistance management (IRM) in the U.S. Maize Belt. One major concern in the use of seed blends is that larval movement among non-Bt and Bt plants could cause additional mortalities of susceptible insects. To address this concern, three caged-field trials were conducted to evaluate larval movement and survival of the corn earworm, Helicoverpa zea (Boddie), in eight seed blends of Cry1Ab/Vip3A maize with 0–30% non-Bt refuges. Each plot consisted of five rows and 21 plants in each row. Each plot was infested on the ear silks of the central plant at R1 stage with 35 F1 neonates produced from field-collected H. zea. After 9–13 d, no live larvae or kernel damages were observed on all Bt plants across all planting patterns and trials. In pure non-Bt plantings, 64.8% of the total larvae recovered moved away from the infested ears and survived on other plants, but most of the recovered larvae (86.8%) were located within a distance of three plants from the originally infested plants, and all live larvae were found on the originally infested or its adjacent rows. Larval survival and distribution were similar among seed blends with non-Bt plants in the centers of the plots, in which larvae predominantly located on the central plants (85.7% of the total recovered) with 100% being found on the central rows. Overall, larval recovery from central non-Bt plants in seed blends was 27.5% less than that from the pure non-Bt plantings. Kernel damage levels followed similar patterns as the number of larvae recovered in the plants, and larvae recovered developed similarly across treatments. Results of the study should have value in understanding the larval movement behavior of H. zea, assessing resistance evolution risk, and refining Bt maize IRM modeling for managing this pest. Additional studies are needed to determine the extent to which the reduction of refuge populations in seed blends influences resistance development of the pest to the Bt maize.

中文翻译：

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Bt 玉米种子混合物中 H. zea 的幼虫运动和存活率 含有 Agrisure Viptera® 性状的非 Bt 和 Bt 玉米种子混合物中 Helicoverpa zea (Boddie) 的幼虫运动和存活率：对抗性管理的影响

摘要 种子混合避难所已被用于在美国玉米带中为 Bt 玉米昆虫抗性管理 (IRM) 寄宿易感昆虫。使用种子混合物的一个主要问题是非 Bt 和 Bt 植物之间的幼虫移动可能导致易感昆虫的额外死亡。为了解决这个问题，进行了三项笼养田间试验，以评估玉米穗虫 Helicoverpa zea (Boddie) 在 Cry1Ab/Vip3A 玉米与 0-30% 非 Bt 避难所的八种种子混合物中的幼虫运动和存活。每个地块由五行和每行 21 株植物组成。每个地块在 R1 阶段用 35 只由田间采集的玉米生产的 F1 新生儿侵染中央植物的穗丝上。9-13 天后，在所有种植模式和试验中，所有 Bt 植物均未观察到活的幼虫或籽粒损伤。在纯非 Bt 种植中，64。回收的总幼虫中有 8% 离开受侵染的穗并在其他植物上存活，但大多数回收的幼虫 (86.8%) 位于距最初受侵染的植物 3 株植物的距离内，并且所有活幼虫都在最初感染的行或其相邻行。幼虫存活和分布在地块中心与非 Bt 植物的种子混合物中相似，其中幼虫主要位于中央植物（回收总量的 85.7%），100% 位于中央行。总体而言，种子混合物中中央非 Bt 植物的幼虫回收率比纯非 Bt 植物低 27.5%。随着植物中回收的幼虫数量的增加，内核损伤水平遵循相似的模式，并且回收的幼虫在不同处理中的发展相似。研究结果对了解 H. zea 的幼虫运动行为、评估抗性进化风险和完善 Bt 玉米 IRM 模型以管理该害虫具有价值。需要进一步的研究来确定种子混合物中避难种群的减少在多大程度上影响了害虫对 Bt 玉米的抗性发展。