Effects of site conditions on the occurrence ofAcalitus rudis(Canestrini) andEriophyes leionotus(Nalepa) (Acari: Eriophyidae) in Czech Republic

Two Birch Species Demonstrate Opposite Latitudinal Patterns in Infestation by Gall-Making Mites in Northern Europe

“…For example, no correlations were found between the occurrence of the birch-galling eriophyoid mites and precipitation or temperature, except for relation of felt galls to rainfall [19]. Consistently with these studies, our data provide equivocal support for the hypothesis that abundance and diversity of eriophyoid mites in boreal forests of Northern Europe are primarily driven by precipitation.…”

“…This approach had been earlier used in ecological studies: for example, different types of galls observed on birch leaves were unequivocally attributed to different species of mites [17, 19, 40]. Several other studies on galling eriophyoid mites associated with deciduous trees also identified mite species using the characteristics of galls rather than of mite specimens [21, 22, 41, 42].…”

“…pubescens may result from differences in phenology [55] or biochemistry [56] of these birch species, but this question remains completely unexplored. The detected differences in the occurrence of different types of eriophyoid galls on two birch species further indicate that the identification of a host plant as ‘ Betula sp.’, that is commonly reported in ecological studies of eriophyoid mites [19, 57, 58] and herbivorous insects [54], is insufficient, and that combination of data on mite galls collected from two birch species (as it had been done in [17]) may easily yield misleading results.…”

“…Previous examinations of temperature and humidity (measured by water stress, rainfall or soil moisture) as factors affecting abundance of eriophyoid galls led to variable results with ambiguous linkage to climate [13, 18, 19]. For example, no correlations were found between the occurrence of the birch-galling eriophyoid mites and precipitation or temperature, except for relation of felt galls to rainfall [19].…”

“…To partially overcome this problem, for the present study we selected eriophyoid mites (Acari: Eriophyoidea), because it is commonly assumed that their galls, which are so distinctive in appearance, can be used for species identification [16]. Therefore, the percentages of leaves with different types of galls have been expected to provide reliable estimates of population densities of these herbivores [17–19]. …”