Gwiazdowski, R.A., van Driesche, R.G., Desnoyers, A., Lyon, S., Wu, S.A., Kamata, N., & Normark, B.B. 2006 Possible geographic origin of beech scale, Cryptococcus fagisuga (Hemiptera: Eriococcidae), an invasive pest in North America.. Biological Control: Theory and Applications in Pest Management 39(1): 9-18.
Notes: Beech scale, Cryptococcus fagisuga Lindinger, is invasive in North America. The immediate source of the introduction was Europe, but its native range may be different. Knowledge of the native range is useful when searching for coevolved natural enemies for classical biological control. We report results of a search for the native range of C. fagisuga, using historical records, field surveys, and molecular phylogenetics. Beech scale feeds exclusively on beech. We review historical accounts of movement of species of Fagus between Europe, Asia, and North America and report on extensive surveys for C. fagisuga on Fagus species in China and Japan. We undertook a phylogeographic study of C. fagisuga throughout its known range using sequences of the mitochondrial gene cytochrome oxidase I (COI). We also investigated the phylogenetic relationships of C. fagisuga to other species of Cryptococcus and related species in the Eriococcidae, using ribosomal DNA (18S). For COI sequences within C. fagisuga, we found one widespread, most-common haplotype in North America, Europe, Turkey, and Georgia; a diversity of slightly (0.1-0.5%) divergent haplotypes in Bulgaria; a diversity of moderately (2.2-2.8%) divergent haplotypes in Georgia and Turkey; and a highly (3.6-4.2%) divergent group of haplotypes in Iran. Phylogenetic analysis of 18S places C. fagisuga within a cosmopolitan clade of eriococcids feeding on other temperate trees (ash, maple, and southern beech). Based on the phylogeographic study, we suggest that the subspecies F. sylvatica orientalis is the native host of C. fagisuga and that natural enemies are best sought on oriental beech in northeastern Greece, the Black Sea drainage basin, the Caucasus Mountains, and northern Iran.