Isozyme analysis using starch gel electrophoresis was used to examine possible genetic differences among populations of 4 Aphthona species which were associated with 4 different Euphorbia species and 4 different environmental types in Europe. Aphthona species evaluated in the study included A. cyparissiae (Kock), A. flava Guillebeau, A. lacertosa Rosenhauer, and A. nigriscutis Foudras. Euphorbia host plant species considered in this study included E. cyparissias L., E. esula L., E. lucida Waldstein-Wartemberg and Kitaibel, and E. virgata Waldstein-Wartemberg and Kitaibel. Cluster analysis of genetic distances obtained from isozyme analysis easily distinguished populations of the 4 flea beetle species as 4 distinct groups. Based on the dendrogram generated from cluster analysis, populations of A. lacertosa and A. nigriscutis were found to be more similar genetically than either species to populations of A. flava or A. cyparissiae. The greatest genetic distance was found between populations of A. cyparissiae and A. lacertosa, which occur in different habitats and on different spurge species. A relatively high genetic distance also was found between populations of A. cyparissiae and A. nigriscutis, which are species that occur in similar habitats and on similar spurge species. Measurable degrees of genetic variability were found between populations (within a species) for 2 of the 4 Aphthona species sampled.
The Eurasian noctuid, Calophasia lunula Hufn., was introduced into North America to control yellow toadflax, Linaria vulgaris Mill., and Dalmatian toadflax, L. genistifolia ssp. dalmatica (L.) Maire and Petitmengin. Larvae feed on the foliage of both toadflax species, but different strains of the moth appear to prefer either yellow or Dalmatian toadflax (Nowierski 1990). Calophasia lunula was first released against yellow toadflax in five Canadian provinces from 1962 to 1968 (Harris and Carder 1971). The moth has been established on yellow toadflax in Ontario since 1965, where it has defoliated up to 20% of the stems (Harris 1988). However, attempts to establish C. lunula on Dalmatian toadflax in Canada have been unsuccessful (Nowierski 1990). Initial releases of the moth in the United States were made in 1968 against both toadflax species with Ontario stock from yellow toadflax (Nowierski 1990). Since then, multiple releases of C. lunula have been made in six western states, including Montana (Story 1985), but until 1989 no establishment had been recorded on either toadflax species.
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