Resistance of Spring Wheats to the Wheat Stem Sawfly, Cephus cinctus Nort. (Hymenoptera: Cephidae): I. Resistance to the Egg

Abstract

Under certain environmental conditions the resistance of wheats to the wheat stem sawfly, Cephus cinctus Nort., may be reduced or even lost. In addition, these varieties are not suitable for all of the region where the sawfly is a problem. To assist in the improvement of the presently resistant wheats, studies were begun in 1953 to determine the nature of the resistance to the sawfly. The present paper deals with the effects of various spring wheats and of different parts of the stems of these wheats on the hatching of the egg of the sawfly and presents evidence for hypotheses on the cause of these effects. Although several authors have reported on resistance to the sawfly (Ainslie, 1920; Criddle, 1915, 1922; Farstad, 1940; Farstad and Platt, 1946; Kemp, 1934; Platt et al., 1948; Roemhild, 1954; Roberts, 1954), none has dealt with the effects of the host on the egg alone.