Stehen bewirtschaftete Honigbienen und einheimische Wildbienen in Konkurrenz um Ressourcen? Eine globale Literatur-Recherche.

The decline of wild bee populations in Central Europe has been triggered by many different factors, such as habitat fragmentations and intensified agriculture. Foraging competition between wild bees and western honey bee colonies (Apis mellifera; in the following referred to as honey bee) may further exacerbate this situation. This is especially true in areas and seasons where shared floral resources are limited. Most of the studies reviewed here indicate negative effects by honey bees on solitary or colony-forming wild bees. Nevertheless, competitive pressure does not necessarily mean a loss of fitness for wild bees as they can partly switch to other flower resources. However, if the substitutes are less suitable or too far away from nesting habitats, negative effects are measurable. The original range of Apis mellifera plays a crucial role in the competitive situation. Where the species has been introduced beyond its natural range, or high densities of bee hives have been installed, clear negative impacts on native wild bees have been recognized. In Central Europe, there is a tendency for stronger negative effects of competition in natural landscapes than in cultivated landscapes. If there are enough species-rich floral offerings and enough suitable nesting habitats for wild bee populations, there is little detectable competition in the latter. In natural areas, where the natural density of pollinators has already reached saturation level, this competitive pressure is detectable. However, the number of Apis colonies, their spatial distribution, as well as their seasonal presence, play a major part in the negative competitive influences on wild bee abundance. [ABSTRACT FROM AUTHOR]