Semester of Graduation

Spring 2026

Degree

Master of Science (MS)

Department

School of Plant, Environmental and Soil Sciences

Document Type

Thesis

Abstract

Hessian Fly (Mayetiola destructor) is a major pest of wheat (Triticum aestivum L. subsp. Aestivum) in the Southern United States. Historically major genes have provided protection against the pest for wheat growing regions globally but new biotypes develop and overcome widely used resistance genes. Development of wheat cultivars with new sources of resistance to Hessian fly is a priority in the Southeastern United States. Increasing winter temperatures lead to more generations of Hessian fly and high selection pressure of resistant biotypes causing the rapid degradation of major gene sources in this growing region. Screening for resistance is time-consuming and labor intensive. With the need to identify new resistance genes, and the historically long timeframe for their integration into breeding germplasm, novel methods are needed for rapid screening, validation, and introgression of new Hessian fly resistance genes.

Single-plant linkage mapping and a new field screening protocol were combined to perform rapid validation and mapping of new Hessian fly resistance gene H33. The developed marker successfully identified H33 in soft red winter wheat germplasm and is already being used for selection in breeding programs. Results from subsequent greenhouse screenings delimited H33 to an approximately 18 Mb interval flanked by two newly developed KASP markers, providing a foundation for further fine-mapping work.

Genomic selection approaches for field screening based on both historic visual ratings and current year pupae count data offer a path to make early generation predictions without the need to screen a large number of lines. Using a new Hessian Fly nursery protocol developed in the 2023-2024 field season we were able to calculate an entry mean heritability of (0.64) for the 2025 Baton Rouge Hessian Fly observation nursery. Pairing marker and historical data with current year screening results could aid with early generation prediction. The genomic prediction models provided predictive abilities of 19% for historic data and 24% for current year screenings. Further assessment of QTL paired with the use of early generation prediction of quantitative gene resistance could help protect and increase the lifespan of the few major genes providing protection against Hessian fly for the Southeastern United States.

Date

4-7-2026

Committee Chair

DeWitt, Noah

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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