hammers@colostate.edu, zjwinn@ncsu.edu, punya.nachappa@colostat.edu, esten.mason@colostate.edu

Wheat stem sawfly (Cephus cinctus Norton) is grass feeding insect native to North America. Damage from the pest predisposes the wheat to lodging, or cutting, which disrupts agricultural practices and is responsible for an estimated $350 million USD loss annually.

Since most of the lifecycle of the wheat stem sawfly occurs within the stem, traditional pest management measures such as pesticides are not as usable. Therefore, the use of other management practices such as biocontrols and genetically resistant wheat cultivars are widely studied. Currently, the only characterized genetic resistance is the solid stem trait (SSt1) on chromosome 3B.

While the solid stem trait helps mitigate damage by limiting movement of the sawfly within the stem, it is an environmentally variable trait. Additional genetic resistance would allow for improved defenses against wheat stem sawfly and limit damage to grower fields.

To identify potential genomic regions of interest for non-solid stem resistance, we observed a historic panel of 1110 Colorado State University wheat breeding program lines from 2014 to 2023 that had cutting, heading date, and solid stem rating data.

Multivariate genome wide association studies using one, two, and all three traits were utilized. This research study is ongoing, so results are not yet finalized. We expect final results within the next couple months.