Population dynamics of gall-inducing eriophyoid mites and seasonal variations in the gall density on linden trees

Abstract

The population dynamics of the gall-inducing mites Phytoptus tetratrichus Nalepa and Eriophyes exilis Nalepa (Eriophyidae) on 50-to 60-year-old trees of Tilia tomentosa Moench, Tilia cordata Mill. and Tilia platyphyllos Scop. are presented. During the 2002-2004 growing seasons, two generations of protogynes and deutogynes occurred. The development of both generations lasted about 2.5-3 months. The maximum density of protogynes was noted in the second half of May while that of deutogynes was recorded a month later. At the end of June, the deutogynes started their migration to their wintering places and by mid-July most galls were empty. For these eriophyoid mite species, the per-leaf gall density increased during the first few days of May, which coincided with the occurrence of deutogynes from the previous year's generation. This seems to be the optimum period for control of these eriophyoid mite species. During the growing seasons 2002-2004, the densities of galls and patch erinea fluctuated greatly, irrespective of the density of eriophyoids actually present on the leaves.