Institut für Bienenschutz
In recent years, a series of scientific publications has documented a decline in flying insects in Germany. This also affects wild bees, which perform a large part of the pollination of wild and cultivated plants. Of the more than 600 species of wild bees in Germany, the bumblebee genus (Bombus) has seen a particularly sharp decline, with a total of 41 species.Three bumblebee species are listed as extinct on the current Red List of Bees in Germany from 2011, and many species have continued to decline sharply since then.The 2002 Red List of Bees in Lower Saxony and Bremen lists 21 bumblebee species, of which 3 species (Bombus confusus, B. pomorum, B. wurfleni) are listed as missing, 2 species (B. ruderatus, B. veteranus) as critically endangered, 4 species (B. distinguendus, B. humilis, B. muscorum, B. ruderarius) as critically endangered and 3 species (Bombus jonellus, Bombus soroeensis, Bombus sylvarum) as endangered. While earth bumblebees and field bumblebees, for example, have been able to adapt well to anthropogenic landscape changes and also thrive in cities, endangered species have increased habitat requirements and limited adaptability. Since the Red List was published in 2002, there have been further, in some cases very severe, declines in the populations of endangered bumblebee species, further increasing the risk of local extinction. For example, B. distinguendus has not been found in Lower Saxony in recent years.The reasons for the declines are land use change and technical innovations in agriculture, combined with a decline in suitable food plants and nesting opportunities. For example, the invention of artificial fertiliser has led to a massive decline in the cultivation of nitrogen-fixing plants such as red clover, which are the main food plants of many bumblebee species. In addition, red clover was also cultivated as a fodder plant for feeding draught animals used in agriculture. This large-scale fodder production has declined massively due to the use of tractors. Land consolidation, with the merging of fields, has led to a decline in undisturbed structural elements such as roadside verges and hedgerows, where bumblebees can find nesting sites. The decline in grazing in grassland in favour of frequent mowing is leading to the destruction of the nests of bumblebee species that nest in the vegetation on the surface and to a significant decrease in flowering plants. Climate change is another significant stressor for bumblebee species that are adapted to cold conditions. In addition, there are many bumblebee-specific parasites, such as wax moths and parasitic wasps, and predators, such as badgers, martens and raccoons, which can cause massive damage to colonies and completely destroy them. These stressors can have varying degrees of impact on the individual phases of the bumblebee life cycle and reinforce each other. The hibernation and subsequent nest-building phase is particularly critical, with many young queens failing to survive. These factors lead to numerous losses, with many queens failing to successfully establish colonies and thus reproduce.Although nature conservation measures in recent years have renaturalised numerous areas in Lower Saxony, which should now offer suitable conditions as habitats for bumblebees, no reversal of the trend in endangered species has been observed to date. Presumably, the populations of rare species are too small and spatially isolated to be able to repopulate renaturalised habitats independently and build stable populations.According to Regulation (EU) 2024/1991, EU Member States are obliged to improve pollinator diversity and reverse the decline in pollinator populations by 2030 at the latest, and subsequently achieve an upward trend in pollinator populations. To achieve this, a population support programme for rare bumblebee species is to be implemented in Lower Saxony as a species conservation measure, providing species-specific support to queens and colonies of these bumblebee species during particularly critical phases of their life cycle, such as colony formation and establishment. The colonies established under supervision will then be transferred to suitable habitats in Lower Saxony, thereby actively increasing the population and possibly reintroducing it to the target region.
Bundesland Niedersachsen
