Genetic Differences between Douglas-fir Beetles (Dendroctonus pseudotsugae) from Idaho and Coastal Oregon

Abstract

The Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins (Coleoptera: Scolytidae), attacks Douglas-fir (Pseudotsuga menziesii) var. menziesii along the Pacific coast and var. glauca in inland areas. In addition to wide geographic separation in association with these host varieties, coastal and inland Douglas-fir beetle populations appear to differ in the production of, and response to, certain pheromones and other chemicals. To assess the degree of genetic divergence between coastal and inland Douglas-fir beetles, samples from coastal Oregon and northern Idaho were subjected to genetic analysis using starch gel electrophoresis. Isozymes produced by 13 gene loci were examined in both populations. Results suggest that differentation at least to the point of race formation has occurred between the 2 groups.