The agricultural value of wild bees is their contribution to crop pollination and studies have shown that abundance, species richness and functional diversity of bees can increase yield and quality of flowering crops. Wild bee pollination services thus carry great value regardless of the presence of managed honeybees. Among other factors, the functional diversity of wild bees increases with species richness of the bees present and the variation in species body-size. Globally, agricultural intensification with increased field sizes and habitat loss and fragmentation has led to a severe reduction in diversity and abundance of wild bees as a result of reduced and scattered food and nesting-resources. Agriculture is the dominant type of land-use in Denmark and 66 % of the Danish landscape is farmland. However, little is known about the diversity of wild bees and associated pollination services in Denmark despite the fact that value of bee pollination of cultured crops is estimated to approach 800 million DKK. This thesis explores how regional, landscape and local differences affect biodiversity and abundance of wild bees (paper I and II) and wild bee foraging behaviour in terms of spatial distribution in the field (II) and the influence of crop variety on preference for pollen and nectar (III). Strawberry (Fragaria x ananassa DUCH.) was used as a model crop for field studies (I, II, III). Strawberry yield and quality are both considerably increased from insect pollination and strawberry is grown throughout Denmark and under widespread cultivation in the rest of the world. A review study (IV) of the literature on wild bees and their pollination services in flowering crops make up the final part of the thesis. The review study aimed to assess how wild bees may respond to landscape parameters based on their biology, in particular diet, habitat requirements and sociality. At a regional scale (I) bee activity-density and species richness was higher in Denmark and Germany compared to South and Mid Norway, whereas the mean bee body size was higher in South- and Mid-Norway. At landscape scale (II) hedges and small clusters of trees positively affected activity-density of bees at scales from 100 m - 2000 m from where the bees were trapped, which shows the conservation value these habitats represent for wild bees in the agricultural land. Forest negatively affected activity-density at all spatial scales possibly due to the low biodiversity offered by many commercially driven, single species, Danish forests. At field scale (I) bee species richness was higher in field margins compared to field centres but there was no difference between centre and margin in body-size or activity-density. Sampling time had an effect on wild bee community composition with higher activity-density and species richness in late May and late June than in early and mid-June (II). Results thus indicate that functional diversity of visiting wild bee assemblages in strawberry differs depending on the spatial and time scale in consideration. There are indications that solitary bees and bumblebees may be affected differently both at landscape and field scale, with solitary bees having a stronger response than bumblebees at small spatial scales. Most of the species and individuals sampled in and near strawberry fields were ground-nesting polylectic solitary species that are known to forage in the family Rosaceae, to which strawberry belong, which indicate that the bees sampled are a source of pollination in strawberries (I, II). Furthermore, the high proportion of polylectic bees found in Danish strawberry fields indicate that an adaptation to a landscape with fragmented resources may already have taken place in the areas sampled. Paper I and III showed that limitations on foraging ability and different foraging needs can drive different visitation patterns in a flowering crop. The review study (IV) found variation in results from different studies on the effects of farming practice and landscape on wild bees. Ecological and life-history differences between bees may be what the drives this variation. Results from all three experimental papers (I, II, III) support this conclusion and future studies may therefore benefit from considering these differences between bee species.