Possible sources of resistance to the wheat midge in wheat

The objective of this study was to find resistance in wheat cultivars to the wheat midge (Sitodiplosis mosellana [Gehin]). A total of 61 spring and 61 winter wheats were assayed in 1992 to 1994. Thirteen selected cultivars were planted in 1994. Three kinds of apparent response to midge infestation were found. Eight winter wheat cultivars suffered neither the usual typical kind nor high numbers of shrivelling of the seeds often attributed to the midge, but produced instead small numbers of shorter and more rounded (tubby) seeds which could be due to midge activity. Cultivar RL5708 differed from all other cultivars in that it showed low proportions of damaged seeds, which were often associated with dead midge larvae. The third group included lines and cultivars showing the typical shrivelling of the seeds due to the wheat midge. In 1993 most late-planted spring wheat cultivars were less affected by the midge than the same cultivars planted earlier probably because of asynchrony between times of wheat flowering and midge oviposition. The incorporation of resistance to the wheat midge into hard red spring wheats should contribute to a reduction of wheat losses in years when wheat midge are abundant.