The importance of foodplants for the distribution and abundance of some stenodemini (Heteroptera: Miridae) of limestone grassland.

The distributions and abundances of five species of Stenodemini (Heteroptera) and one of Rhopalidae (Heteroptera) were monitored over a 2-year period on a 1 ha square of limestone grassland near Oxford.At the same time, the distribution of all grass species in the area was mapped.By comparing the distributions of insects with their potential foodplants, and by carrying out feeding trials on selected insects, an outline of the foodplants selected by different species of insect was built up.Each insect fed on several foodplants at once, but this spectrum often changed seasonally and with the age of the insect. Most grass species were used by at least one insect species.There were considerable overlaps between the feeding spectra of different bugs. However, ecological separation was usually achieved by emergence timing and/or feeding on different parts of the same grass species.One species pair remained with an almost complete overlap in the resources that were measured (Notostira elongata and Megaloceraea recticornis). Since these bugs reached very high combined densities, and one of them suffered very high mortality at a time of overlap, it is possible that these two species were competitors.Sward height did not influence insect distributions within the range present on the study site. Nymphal parasites were extremely rare and unlikely to have affected their hosts' distributions.