Association of the wheat stem sawfly with basin wildrye

Abstract

The association of the wheat stem sawfly (Cephus cinctus Nort., Hymenoptera: Cephidae) and basin wildrye (Elymus cinereus Scribn. & Merr) was investigated in 2 wildrye stands in southern Idaho during the summers of 1982 and 1983. From 62 to 88% of wildrye plants were infested with the sawfly at the Idaho National Engineering Laboratory and Craters of the Moon National Monument. Plant phenology was a good predictor of sawfly emergence. Larvae that developed within culms consumed vascular tissues and may have impaired transport of water and carbohydrates. Seed weight and the number of caryopses developing within wildrye florets were significantly reduced in culms containing sawfly larvae (P<0.006 and P<0.018, respectively). Germination rates of seeds from infested and non-infested culms were not significantly different (P>0.05).