D3073: Assessment of awns and hairy glumes in spring wheat lines as a form of resistance against the orange wheat blossom midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae)

Wheat is a major crop in Canada and having effective, low-cost pest management solutions is critical. The wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae) is an important pest found throughout the country, causing significant yield loss through larval feeding on the developing seed. Control of this pest predominantly relies on antibiosis, host plant resistance in the form of a single gene, Sm1. Insects have overcome similar resistance genes in relatively short time periods, making it crucial to find alternative methods of control. This has not occurred to date for Sm1. Antixenotic host plant resistance through physical barriers may reduce oviposition and consequently, kernel damage. To investigate the impact of awns and hairy glumes on egg laying, a group of spring wheat lines were developed with these traits. Four combinations of these two morphological traits were exposed in a factorial design to wheat midge adults both in choice cages under controlled laboratory conditions and in field plots. The choice cages show no effect of hairy glumes and awns on oviposition preference, with the different lines in each trait group accounting for most of the variation in egg numbers. Preliminary results indicate the same trend in the field, with the degree of seed damage differing among lines with the same trait. This study suggests that some wheat lines reduce oviposition and seed damage, but that it is not due to the presence of awns or hairy glumes, and further research should look into the source of resistance in those lines.