Seed damage by Sitodiplosis mosellana (Diptera: Cecidomyiidae) to spring wheat cultivars with the Sm1 gene

Six resistant spring wheat cultivars with the Sm1 gene were assessed for seed damage by the orange wheat blossom midge (Sitodiplosis mosellana (Gehin) (Diptera: Cecidomyiidae)) in laboratory and field tests. All resistant cultivars deterred larvae from developing on the seed and had significantly less yield losses than susceptible wheat cultivars. Vesper was the first cultivar with Sm1 that also deterred oviposition by the wheat midge. Seed damage to all resistant cultivars decreased the later plants were exposed to adult midge from the time spikes emerged from the boot until anthesis. Spikes of susceptible wheat cultivars had lower yield losses when exposed two or more days after emergence than spikes exposed at the time of emergence. Seed damage to resistant wheat caused dorsal and lateral distortions of the seed and often altered seed colour and shape. The pedigree of the resistant cultivars had no effect on the extent of seed damage. Shaw wheat had the least amount of seed damage and no third instars on the seed in both field and laboratory tests. All other cultivars had a few small third instars and similar levels of seed damage in laboratory tests, with Fieldstar being the least effective. In at least one mean site-year Shaw had significantly less yield losses than the other resistant cultivars. It is recommended that Shaw be used as the standard for the selection of future spring wheat cultivars with Sm1.