© 2000 Heron Publishing—Victoria, Canada
Genetic diversity and bark physiology of the European beech (Fagus sylvatica): a coevolutionary relationship with the beech scale (Cryptococcus fagisuga)
Doris Krabel (1, 3) and Ralf Petercord (2)
1. Abteilung Forstgenetik und Forstpflanzenzüchtung der Georg-August Universität Göttingen, Büsgenweg 2, D-37077 Göttingen, Germany
/ 2. Institut für Forstbotanik und Forstzoologie, Technische Universität Dresden, Pienner Strasse 7, D-01735 Tharandt, Germany / 3. Institut für Forstzoologie der Georg-August Univerität Göttingen, Büsgenweg 3, D-37077 Göttingen, Germany (krabel@forst.tu-dresden.de
) / Received October 2, 1998
Summary
In 1994 and 1995, the degree of infestation by the beech scale (Cryptococcus fagisuga Lind.) was recorded on 120 beech trees (Fagus sylvatica L.) in the Pless Forest near Göttingen, Germany. Simultaneously, the trees were characterized genetically and compounds of
primary and secondary metabolism of beech bark were analyzed. A correlation was established between beech scale infestation
and the genotype of the host trees, based on gene locus A of isocitrate dehydrogenase (IDH-A). The fraction of infested beech
trees was higher in the heterozygous genotype A2A3 group than in the homozygous genotype A2A2 and A3A3 groups, whereas the
fraction of beech trees with decreasing infestation from one year to the next was lower in the heterozygous genotype A2A3
group than in the homozygous genotype A2A2 and A3A3 groups.
Concentrations of soluble carbohydrates, protein amino acids and proanthocyanidins were determined in the inner and outer
bark of trees with differing degrees of infestation. The results indicate that the defense reaction of beech against infestation
by beech scale comprises multiple processes in which nutrient availability to the beech scale is reduced by concentration
shifts and by the formation of inhibiting compounds.
Keywords:
bark compounds, host–parasite relationship, isocitrate dehydrogenase, phytophagous insects, population dynamics.
