The bumble and cuckooo bees (Hymenoptera: Apidae: Bombini; Bombus spp. and Psithyrus spp., respectively) are important plant pollinators and any decline in numbers or species constitutes a significant threat both to biological diversity and to whole economies. The distribution, status and factors threatening all 60 known taxa (species and subspecies) of Bombini of 11 countries of Western and Central Europe (Belgium, the Netherlands, Luxembourg, Denmark, Germany, Switzerland, Austria, Czech Republic, Slovakia, Hungary, Poland) were assessed from the beginning of the 20th century. The analysis was based on a literature review, unpublished data, personal communications, our own observations, and an expert review. The IUCN Red List categories were used for assessing the threat of extinction. Eighty per cent of taxa were threatened in at least one country of the region, and 30% of taxa were threatened throughout their range in the countries considered. More species went extinct per country in the second than in the first half of the 20th century, and four taxa went extinct in all 11 countries during 1951–2000. Amongst the factors adversely affecting the Bombini anthropogenic factors (particularly those associated with large-scale farming schemes) appear to be of greater importance than natural factors. To halt population declines and species extinctions it will be necessary to preserve aspects of traditional farming practices and for all Bombini to be afforded legal protection in all countries of the region. The implementation of the European Union's Common Agricultural Policy is likely to have the greatest single impact upon pollinators in the near future.
Pollinating insect populations, essential for maintaining wild plant diversity and agricultural productivity, rely on (semi)natural habitats. An increasing human population is encroaching upon and deteriorating pollinator habitats. Thus the population persistence of pollinating insects and their associated ecosystem services may depend upon on man-made novel habitats; however, their importance for ecosystem services is barely understood. We tested if man-made infrastructure (railway embankments) in an agricultural landscape establishes novel habitats that support large populations of pollinators (bees, butterflies, hoverflies) when compared to typical habitats for these insects, i.e., semi-natural grasslands. We also identified key environmental factors affecting the species richness and abundance of pollinators on embankments. Species richness and abundance of bees and butterflies were higher for railway embankments than for grasslands. The occurrence of bare (non-vegetated) ground on embankments positively affected bee species richness and abundance, but negatively affected butterfly populations. Species richness and abundance of butterflies positively depended on species richness of native plants on embankments, whereas bee species richness was positively affected by species richness of non-native flowering plants. The density of shrubs on embankments negatively affected the number of bee species and their abundance. Bee and hoverfly species richness were positively related to wood cover in a landscape surrounding embankments. This is the first study showing that railway embankments constitute valuable habitat for the conservation of pollinators in farmland. Specific conservation strategies involving embankments should focus on preventing habitat deterioration due to encroachment of dense shrubs and maintaining grassland vegetation with patches of bare ground.
AimLandscape composition and spatial configuration of habitat patches are important determinants of biodiversity in fragmented semi‐natural habitats spread across agricultural landscapes. However, little attention has been paid to man‐made structures that can moderate spatial processes affecting pollinator communities. In a large‐scale study, we explored the importance of railway embankments for the turnover of pollinator species in agricultural landscapes. Because species differ in vulnerability to landscape composition and patch configuration, we also accounted for body size as well as food specialization of pollinators.LocationKraków area, Poland.MethodsWe sampled pollinating insects (bees, butterflies and hoverflies), at 25 study sites located along railway lines in the region of Kraków, Poland. Control grasslands for the embankments included 19 patches, located among crop fields, in which pollinators were sampled. We assessed the relationships between dissimilarity and distance for bee, butterfly and hoverfly trait groups on embankments and grasslands using Moran's Eigenvector Maps.ResultsThe dissimilarity for food‐non‐specialized bees on embankments was spatially structured: sites that were closer together were also less dissimilar in their community composition than more distant ones. Dissimilarity was also spatially aligned for large‐bodied butterflies and hoverflies on embankments. The species dissimilarity of pollinators divided into trait‐based groups was not spatially structured on grasslands.Main conclusionOur study highlights the potential function of railway embankments as corridors for at least some pollinator populations. Landscape managers should include railways in green networks to improve spatial processes linked with the distribution and turnover of pollinator species in agricultural landscapes. Thus, railway embankments and their correct management may be a good example of man‐made alterations in the environment that meet the demands of both civilization and biodiversity conservation.
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