Hemiptera community and species responses to grassland sward islets

Sward islet is a term that has been used to describe a patch of longer vegetation in a pasture produced by a reduction in cattle grazing around their dung. They are known to affect the abundance and distribution of grassland arthropods. Hemiptera, like other groups, are found in higher densities within islets than the surrounding sward. Does this modify the community composition or is there just a density effect? Evidence from a paired (islets, non-islets) study at an Irish cattle-grazed site, would suggest that although a change in the density of species explains much of the patterns observed, some species respond to islets in different ways. Grassland Auchenorrhyncha were dominated by two genera, Javesella (mostly J. obscurella and to a lesser extent J. pellucida) and Macrosteles (mostly M. viridigriseus with some M. laevis and M. sexnotatus). The nymphs and to a lesser extent the adults, showed contrasting distribution patterns in relation to islets. Javesella were more common in the islets, whereas Macrosteles showed little difference between the two sub-habitats. Possible reasons for the difference in sub-habitat choice between these two Auchenorrhyncha taxa are discussed.