Genetic Differences in Resistance of Range Grasses to the Bluegrass Billbug, Sphenophorus parvulus (Coleoptera: Curculionidae)

Abstract

Significant differences in plant resistance to larvae of S. parvulus Gyllenhal were found among and within range grass species and interspecific hybrids in nurseries at the Decker, Montana [USA], surface mine and on a site near Miles City, Montana. Slender wheatgrass (Elymus trachycaulus) and related species were particularly susceptible. Crested wheatgrass (Agropyron cristatum and A. desertorum), thickspike wheatgrass (E. lanceolatus), Russian wildrye (Psathyrostachys juncea), and salina wildrye (Leymus salinus) were among the species with a relatively high degree of resistance to the insect. Clonal lines of the Elytrigia repens .times. E. spicata hybrid differed significantly in resistance. Over 50% of the total phenotypic variation among the hybrid lines was attributed to genetic effects, indicating that selection for resistance would be effective.