The European Red List of bees has assessed the status of all native bee species to Europe or naturalised before AD 1500, a total of 1,965 bee species. Species introduced to Europe by man after AD 1500 were not considered in the assessment. Species that are of marginal occurrence in Europe were classed as Not Applicable (NA).
The initial species list was based on Kuhlmann et al. (2014). The taxonomy of the genus Andrena largely follows Gusenleitner and Schwarz (2002).
For all the bee species assessments, the following data were compiled:
The task of collecting the initial data was divided up taxonomically, by family, sub-family or genera. Experts collected information (see acknowledgement section) about each species based on published and unpublished data and their expert opinion. The IUCN Species Information Service (SIS) was used to enter and stored all the species data.
Seven workshops were held throughout the three-year lifespan of the project to review and discuss a selection of species assessments and maps, add new information and agree on the final IUCN Red List Category and Criteria (both at the European and EU 27 levels).
All the species from the family Melittidae, most species of the family Andrenidae (all species from the genera Camptopoeum, Clavipanurgus, Flavipanurgus, Melitturga, Panurginus, Panurgus and Simpanurgus, and a selection of Andrena species), the species of the genera Halictus, Nomiapis and Lasioglossum (family Halictidae) and the species of the genera Xylocopa, Ceratina and Bombus (family Apidae) were assessed at small workshops organised in Brussels and attended by key experts and IUCN staff. The remaining species were reviewed and discussed by email correspondence with relevant experts.
Following the workshops, the data were edited, and outstanding questions were resolved through communications with the experts. Consistency in the use of IUCN Criteria was checked by IUCN staff. The resulting finalised IUCN Red List assessments are a product of scientific consensus concerning species status and are backed by relevant literature and data sources.