Response of doubled haploid lines derived from maize population BS39 to leaf injury by the fall armyworm, Spodoptera frugiperda

Authors: Abel, Craig; Woolfolk, Sandra; FREI, URSULA - Iowa State University

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2025
Publication Date: 12/12/2025
Citation: Abel, C.A., Woolfolk, S.W., Frei, U.K. 2025. Response of doubled haploid lines derived from maize population BS39 to leaf injury by the fall armyworm, Spodoptera frugiperda. Southwestern Entomologist. https://doi.org/10.3958/059.050.0428.
DOI: https://doi.org/10.3958/059.050.0428

Interpretive Summary: The fall armyworm, a pest of maize native to the Americas, causes economic damage to the crop by injuring leaf, tassel, and ear tissue. The pest is resistant to several classes of insecticides and genetically modified maize so breeders are looking for new tactics for its control. The objective for this study was to evaluate fall armyworm leaf feeding resistance in inbred lines derived from maize population BS39. BS39 was developed from tropical maize and bred for adaptation to temperate environments to give breeders in the U.S. Corn Belt new genetic material for crop improvement. One of the inbred lines, BS39_DH_012, was moderately resistant to fall armyworm and showed potential for enhancing maize with resistance to this economically important pest. The inbred line was variable in its response to fall armyworm leaf injury and this variability could be used to help understand the mechanism of resistance which will strengthen the efforts to breed this trait into commercial maize for the benefit of U.S. producers.

Technical Abstract: Maize (Zea mays L.) breeding is crucial for optimizing production in different environments. For temperate maize, plant breeders have focused on interbreeding elite x elite germplasm resulting in the narrow use of a few select populations. To broaden the genetic background of commercial maize, researchers integrate germplasm from tropical maize to boost crop performance and reduce genetic vulnerability. Maize population BS39 was developed from tropical founders and developed for adaptation to temperate environments. Doubled haploid inbred lines have been developed from BS39 to enable temperate maize research. In this study, ten doubled haploid lines were tested for leaf feeding resistance to fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). BS39 and the doubled haploid line derived from it, BS39_DH_012, were both moderately resistant to fall armyworm leaf injury. In 2021 and 2022, leaf injury scores 14 days after infestation were 5.20±0.4 and 4.95±0.3 for BS39, 5.54±0.4 and 4.92±0.3 for BS39_DH_012, which were all significantly higher than the resistant check Mp708 scores of 3.78±0.4 and 2.91±0.3. Among all the DHLs, BS39_DH_012 had the lowest scores across all years and the combined year analysis. A difference was noted in the level of resistance that was manifested in V7 versus V8 BS39_DH_012 plants that warrants further investigation. Understanding the mechanisms underlying this difference could help determine the factors conferring resistance to FAW leaf injury.