Ecological aspects of dispersion of gall mites in the vertical profile of the birch crown

Abstract

In stands of birch Betula pendula Roth in the eastern Krušné hory Mts. the occurrence of the gall mites Acalitus mdis Canestrini and Phyllocoptes lionotus Nalepa was studied in terms of their dispersion in the tree crown. Statistical analyses of data on the infestation of birch with gall mites in the height transects of the eastern Krušné hory Mts. were conducted (1995-2001) as well as detailed monitoring of their dispersion on selected heavily infested sample trees. In 1995-2001 the infestation of birch stands of the eastern Krušné hory Mts. increased. The population dynamics of A. rudis revealed important deviations, the abundance of P. lionotus was lower and in terms of time changes it was incidental. Detailed investigations proved that the gall mites favoured leaves formed in the stage of leaf opening in the lower part of the crown. The horizontal distribution of A. rudis in the crown was limited.