SEARCH FOR QUALITY PARAMETERS TO ESTIMATE THE CONDITION OF PTEROSTICHUS-CUPREUS (COL, CARABIDAE) IN VIEW OF POPULATION-DYNAMIC MODELING

Habitat quality affects the condition of predatory beetles in terms of size and weight. Carabid body weight and size are defined and measure d in many ways. The way of collecting and preserving of beetles affect s these parameters. This makes comparison between studies difficult. T his paper presents more precise methods to determine the condition of the carabid P. cupreus in farmland. Beetles were caught alive by using pitfall traps and were weighted. Elytra maximum length and area were measured by image analysis. The elytra area appeared to be a good indi cator for beetle size. The relative fresh weight was defined as the fr esh weight/elytra area. To convert weight from formalin trapped beetle s into fresh or dry weight, relationships between different weighing p rocedures were established. Analyses were made of the relation between various weight and size parameters. The relative fresh weight of both sexes increases significantly early in the season. Weight and relativ e fresh weight do not differ significantly between sexes. Since female s are expected to respond more clearly to environmental circumstances in terms of weight, variability should be higher. This is best reflect ed in the relative fresh weight which is much more variable in females than in males. Therefore this parameter is most suitable for assessin g individual conditions. For P. cupreus the multiplication factor to t ransform alcohol weight into fresh weight is 1.19. Because all dry, fr esh and alcohol weights are highly correlated it depends on the resear ch questions and circumstances which method to choose.