The Effect of Cereal and Grass Management on Staphylinid (Coleoptera) Assemblages in South-West Ireland

Abstract

(1) The effects of different cereal and grass management regimes on summer staphylinid assemblages were examined in hay meadows, lightly grazed pastures, silage fields, spring cereals, and winter cereals with routine pesticide application in south-west Ireland. (2) Forty-nine sites were sampled for adult Staphylinidae using pitfall traps and a D-vac suction sampler in June and July 1986. Comparisons between sites using species composition data were carried out using detrended correspondence analysis. (3) Large differences in staphylinid assemblages occurred between undisturbed meadows and pastures (without cultivation, cutting, heavy grazing and fertilizer use), and disturbed silage fields and cereals. The latter were rapidly recolonized after physical disturbance such as cutting and cultivation, once a vegetation layer was re-established. The assemblages of second-cut silage fields, spring cereals with a welldeveloped canopy, and of winter cereals, were very similar. (4) Dimethoate application resulted in a reduction in species richness in cereals, and there were more species in small fields, although the latter was due to the occurrence of species which were rare overall in cereals. No effect of propiconazole, the most frequently used fungicide, was detected. (5) Rapid recolonization in heterogeneous landscapes, as in this study, may lessen the perceived impact of disturbance factors, which may have a much greater impact in more homogeneous landscapes. Nonetheless, the results indicate that, with careful site selection, multivariate analysis of staphylinid species composition data can be a useful supplementary technique to experimental plot studies.