Wheat Stem Sawfly (Hymenoptera: Cephidae) Revisited

The wheat stem sawfly, Cephus cinctus Norton, is a major pest of spring wheat in the northern Great Plains of North America. Cropping systems developed during the early settlement years, summer fallowing and strip cropping, and drastic increases in wheat production led to wheat stem sawfly becoming a pest. The development and release of a solid-stemmed resistant cultivar, ‘Rescue’, in the 1940s and the subsequent release of improved cultivars have reduced losses significantly in regions heavily infested by the sawfly. The difference in yield potential of resistant cultivars compared with susceptible cultivars is less in the western range of the pest, and explanations are provided. Although resistant cultivars have reduced losses, the undesirable agronomic characteristics and lower yield potential have suppressed grower acceptance of the solid-stemmed cultivars. The lack of an accurate damage-prediction program forces growers to gamble between planting a susceptible cultivar and suffering yield loss because of the wheat stem sawfly or planting a resistant cultivar and suffering yield or quality reduction. Continued economic losses in spring wheat and recent infestations of winter wheat mandate continued research on this pest.