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.

Pollinator foraging behavior plays a key role in breeding and therefore affects the evolution of the orchid reproductive strategy. Food-deceptive orchids usually implement a generalized plant pollination strategy and a relatively diverse group of pollinators visit them. Dactylorhiza majalis is a food-deceptive, early-flowering orchid that relies on insect-mediated pollination. This study's objectives were to identify D. majalis' pollinators and flower visitors and their foraging behaviors on D. majalis inflorescences. We also assessed the bending movement time to determine the relationship between bending time and the duration of pollinators' visits. To assess pollination efficiency, we measured the spur length of D. majalis flowers, which is expected to affect the mechanical fit to pollinators/Bpotential^pollinators. The arthropod fauna were investigated to examine the availability of Bpotential^pollinators in populations. We identified Apis mellifera as this orchid's main pollinator and confirmed that few of the flower visitors belonged to Diptera (12 individuals, 9 taxa), Hymenoptera (3 individuals, 3 taxa), or Coleoptera (2 individuals, 2 taxa) in our dataset, which was collected over a 2-year period and includes 360 h of video. The arthropods were collected by a sweep net in D. majalis populations and there were fewer Hymenoptera (2.9-23.2%) and Coleoptera (4.4-23.8%) visitors but more Diptera (23.3-58.6%) visitors. We found that A. mellifera foraged in different ways on D. majalis inflorescences, thereby resulting in cross-pollination and/or geitonogamy; however, the bending time data supported the hypothesis about promoting cross-pollination while decreasing self-pollination, but these data do not exclude the possibility of geitonogamy.

The increased introduction of non-native species to habitats is a characteristic of globalisation. The impact of invading species on communities may be either linearly or non-linearly related to the invaders' abundance in a habitat. However, non-linear relationships with a threshold point at which the community can no longer tolerate the invasive species without loss of ecosystem functions remains poorly studied. We selected 31 wet meadow sites that encompassed the entire coverage spectrum of invasive goldenrods, and surveyed the abundance and diversity of pollinating insects (bees, butterflies and hover flies) and native plants. The species richness of native plants decreased linearly with goldenrod cover, whereas the abundance and species richness of bees and butterflies decreased non-linearly with increasing goldenrod cover. However, no statistically significant changes across goldenrod cover were noted for the abundance and species richness of hover flies. Because of the nonlinear response, goldenrod had no visible impact on bees and butterflies until it reached cover in a habitat of about 50% and 30-40%, respectively. Moreover, changes driven by goldenrod in the plant and

Loss of suitable seminatural habitats and homogenization of crop types have led to the population decline of pollinating insects in farmland. As these insects support crop production, many practical efforts aim to sustain pollinator diversity which is especially challenging in intensively managed and homogeneous farmland. However, there are ongoing changes of the farmland toward its multifunctionality that includes, for example, wind farm development. Windmills are often built within crops; thus, we examined if the noncropped area around windmills can be valuable habitats for wild plants and pollinating insects: bees, butterflies, and flies. Species richness, abundances, and species diversity index of plants and pollinators around windmills were similar to those found in grassland patches (a typical habitat for these insects) and higher than in the adjacent crops. Pollinator diversity index and species richness at windmills increased with the distance to the nearest grassland patch and windmill. The population sizes of pollinating insects were also positively associated with plant diversity. Particular groups of pollinators showed specific habitat associations: bees occurred mostly at windmills, butterflies were highly associated with grasslands, while flies occurred in a similar number at windmill and on grasslands. Since windmills are frequently built within extensive homogeneous fields, thus, they introduce pollination services into the interior of cropped areas, contrary to field margins, road verges, or seminatural grasslands. Thus, although the development of wind farms has various negative environmental consequences, they can be alleviated by the increase of the local population size and diversity of wild plants and pollinating insects at windmills.Electronic supplementary materialThe online version of this article (10.1007/s11356-017-0864-7) contains supplementary material, which is available to authorized users.

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