Beetle bank

Abstract: Significant differences in the overwintering densities of predatory carabid and staphylinid beetles and spiders occurred on an 'island' grassy bank habitat composed of blocks of Agrostis stolonifera, Dactylis glomerata, Holcus lanatus and Lolium perenne, within and between winters during a 7-year study. 2 Densities of the predators over the last three winters of the study were greater in the bank than in the boundary of the field in which the bank was situated. 3 Succession occurred in plots of L. perenne, with D. glomerata fully replacing this species. Plots of D. glomerata and H. lanatus remained virtually mono- specific. 4 Over the period of study, the beetle bank maintained its role in providing overwintering habitat for polyphagous predators and carabid diversity has increased since the bank was first established. Beetle banks were therefore shown to contribute to conservation biodiversity in an agroecosystem.

Abstract: Severe declines have occurred in the populations of wild game birds in Britain. This has been attributed to agricultural intensification, leading to the loss of invertebrates vital within chick diets, fewer feeding resources for adults, and inadequate provision of nesting and brood-rearing habitat. This paper explores the potential value of simple sown grass strips - beetle banks - in providing these resources, and compares results with functionally similar conventional field margins. The data indicate that beetle banks can contribute useful, albeit lower, densities of chick-food than conventional margins. These resources are more abundant later in the season, which may have implications for early hatched chicks. Beetle banks provide considerable quantities of nesting cover for adults, although sheltering conditions may never be as satisfactory as in well managed hedgerows. Given the ease and low cost of establishment of beetle banks, we suggest that they may be valuable components within a range of game management techniques on the farm, as a 'spin-off' to their primary role as overwintering habitat for polyphagous predators. They may be important particularly where resources for game birds are impoverished, but clearly cannot substitute for suitably managed field margins.

Abstract: Summary Overwintering polyphagous predator density and composition was compared within a mid-field overwintering refuge (“beetle bank”) and two conventional hedgebanks over a 5-year period. During the study predator densities in the beetle bank were similar to or greater than those in the conventional hedgebanks. Whilst predator densities remained relatively stable in both of the hedgebanks over time, densities fluctuated significantly within the beetle bank. Many of the species recorded on the beetle bank are considered to be important predators of cereal aphids. The results are discussed in terms of the implications of creating such a habitat for the biological control of cereal aphids.