Pitfall trapping is one of the most commonly used methods of sampling ground-dwelling arthropods. There are many studies on the effect of design of pitfall traps on their capture efficiency but, so far, none on the influence of the colour of the pitfall trap. In this study the abundances of seven invertebrate groups (Apidae, Araneae, Carabidae, Diptera, Formicidae, Isopoda, Vespinae) caught in pitfall traps of different colours (white, yellow, green, brown) at a dense and dry grassland site in Northwestern Germany were determined. White and yellow pitfall traps caught by far the highest numbers of individuals of Apidae, Araneae, Carabidae, Diptera and Formicidae. Isopoda were most abundant in the catches of green and brown traps. Differences among numbers caught were significant for Apidae, Araneae, Carabidae and Diptera. The effect of colour on the catches did not differ significantly between sites. Knowledge of the variation in the catching efficiency of differently coloured pitfall traps is important for designing invertebrate surveys, both from a scientific and ethical point of view.
One of the most compelling challenges for conservation biologists is the preservation of species with restricted ranges. Carabus olympiae Sella, 1855, a ground beetle species inhabiting two small areas in the western Italian Alps, is an example of a steno-endemic and endangered insect species. Despite the fact that this species is historically well known to professional and amateur entomologists, its autecology is virtually unknown. In the present study we used pitfall traps to study habitat selection and phenology, and radiotelemetry to measure differences in movement parameters between sexes, habitats and periods. Data from pitfall trapping suggested that C. olympiae actively selects both shrubberies (alpen rose Rhododendron ferrugineum and bilberry Vaccinium myrtillus) and beech forests and avoids pastures, and that population size peaks in July. All radio-tagged individuals (n = 21) moved without a preferred direction, and were more active at night than by day. Males covered greater distances and had more tortuous trajectories than females. Distances covered in forests and alpen rose shrubberies were not significantly different, but paths in beech forests were more convoluted than in shrubberies. The movement pattern observed fits the requirements of a typical "olfactory-tactile" insect predator that looks for prey by systematically exploring its territory. Movement parameters suggested that both beech forests and alpen rose shrubberies are suitable for this species and indicated that the spatial distribution of shrubs in shrubberies can constrain trajectories. The implications for conservation are: (i) any human intervention which results in enlargement of the present coverage of pastures should be controlled; (ii) forest management may be tolerated, with the condition that alpen rose shrubberies remain or develop after tree-cutting; (iii) once a shrubbery has established, it should be preserved through appropriate management.
Exposed Riverine Sediments (ERS) are often characterised by a high diversity of microhabitats due to strong lateral gradients in temperature, humidity, inundation frequency and availability of aquatic food resources and to variations in the degree of vegetation cover, sediment size and sorting. This variation, potentially in combination with interspecific competitive interactions, is thought to drive the microspatial distribution of ERS invertebrates. This research investigated the microspatial distribution of six ERS specialist beetles across three discreet patches of ERS. In particular it examined the temporal stability of species distributions, and their spatial association with environmental variability and other species. The research used a grid of 204 modified dry pitfall traps over six sampling periods in which weather conditions and water levels were stable, and used the Spatial Analysis by Distance IndicEs (SADIE) method to test the significance of spatial distributions and associations. Strong and significant microspatial zonation was observed for all species, and with few exceptions these distributions were remarkably stable across the study period. This zonation was mainly associated with elevation and proximity to the water, and several species were consistently spatially associated or disassociated with one another. This suggests that laterally more extensive patches of ERS support more species. Operations that reduce the size of ERS patches, such as channelisation, aggregate extraction and regulation are therefore likely to reduce ERS invertebrate diversity.