While collecting pollen and nectar, pollen attaches to the insect's body. The result is that bees transfer pollen grains from flower to flower. In this way, they help plants sexually reproduce. Some plants can only be pollinated by certain species. Therefore, the loss of bee diversity can lead to loss of plant diversity. A recent European regional assessment has reported the status of all 1,965 European bee species. The geographic range of this assessment extends from Iceland in the west to the Ural Mountains in the east, and from Franz Josef Land in the north to the Mediterranean in the south. The Canary Islands, Madeira, and the Azores were also included.
9.2% of bee species are considered threatened at the European level, though this proportion is uncertain due to the high number of species for which there is insufficient data. For 56.7% of the bee species in Europe, there was not enough data to evaluate the risk of extinction; these species were classified as data-deficient. The honey bee (Apis mellifera) has been evaluated as data-deficient on the European Red List. This species is native throughout Europe (except Iceland, the Faeroe Islands, northern Scandinavia, and the Azores), but it is not known whether the species still has self-sustaining wild populations in Europe.
Compared to all other European wild bees, bumblebees are the best-studied group. According to the European Red List, 23.6% of bumblebee species are threatened with extinction, and populations are decreasing for 45.6% of bumblebee species. Land-use changes resulting in loss of natural environment is a serious threat to many bumblebees in Europe. The amount of habitat for the critically endangered bee species Bombus cullumanus has been greatly diminished, resulting in an 80% population loss, in the last decade. A primary cause of this has been farming practices that involve removing clovers, the main food source for B. cullumanus. This bee species was previously widespread, but now only exists in a few locations across Europe. Additionally, Bombus fragrans (the largest bumblebee species in Europe, and red-listed as endangered) is also seriously threatened by intense agricultural land-use, as this is destroying areas of its native habitat in the steppes of Ukraine and Russia. Rising temperatures and extended periods of drought are also responsible for major changes in bumblebee habitat. For example, Bombus hyperboreus (the second largest bumblebee species in Europe, and red-listed as vulnerable) is strictly limited to Scandinavian tundra and the extreme north of Russia. Continued climate change is likely to dramatically reduce B. hyperboreus's habitat and lead to population losses.
The geographic distribution of bee species richness in Europe is shown in figure 1. The relatively low bee diversity observed on the Balkan Peninsula, north of Greece, is most likely the result of the relatively low amount of research and sampling effort conducted in this region.
Figure 1: Geographical distribution of bee species richness in Europe.
The geographic distribution of bee species endemism in Europe is shown in figure 2. There is a high number of endemic bee species in southern Europe. Similar to the species richness map, the relatively low bee endemism observed in large areas of the Balkan Peninsula is most likely the result of the relatively low amount of research and sampling effort conducted in this region. Many southern-European bee species also occur in neighboring areas of Asia and north Africa. Though these species are endemic to these biogeographic regions, they are not represented in figure 2.
Figure 2: Geographical distribution of bee species endemism in Europe.
The expansion- and intensification of agriculture is a major threat to bees in Europe. Associated with this is the loss of natural habitat, widespread use of insecticides and herbicides, and livestock farming (resulting in grazing regimes that are damaging to grasslands and fragile ecosystems). Additionally, the increased frequency of fire in Mediterranean ecosystems, immediately followed by grazing on these post-fire plant communities, decreases bee diversity in these fragile ecosystems.
Urban- and commercial development is another major threat to bees in Europe. Tourism in coastal regions has led to increases in local populations and number of hotels. It is estimated that by 2020 there will be ~350 million tourists visiting the Mediterranean coastal region. Along the mainland Mediterranean coasts of Spain, France, and Italy, 75-80% of the coastal sand dunes have been destroyed by tourism, urbanization, and industry. Sand dune ecosystems in Greece and Portugal are also under urbanization pressure. These threatened ecosystems are home to bee species such as Osmia balearica and Osmia uncicornis. In alpine regions of Europe, a large amount of natural habitat has been converted to ski areas or has been destroyed for other tourism-related infrastructure development. Red-listed alpine bees such as Bombus brodmannicus are threatened by skiing-related development. An additional threat related to urban development, sea walls in low-lying coastal areas heavily impact coastal habitats, especially saltmarshes. This directly impacts specialized endemic bee species such as Colletes halophilus.
Numerous projects, both restoration practice- and scientific research-based, currently address various threats to pollinators, though our knowledge on pollinator diversity, population dynamics, and threats remains limited. And as mentioned above, there is insufficient data for many, if not most, pollinator species and populations. The POL-AEGIS project represents a pioneer effort to fill gaps of knowledge. This project focuses on a wide range of the Aegean archipelago, and the project spans from january 2012 to september 2015. The aims of the project are to assess pollinator diversity (ecological and genetic) and investigate the causes of pollinator diversity loss. Here, bees are not the only pollinators studied, and this allows for a more holistic approach to understanding the status of the region's pollinator communities. Successful achievement of the aims of this project are expected to increase pollination studies and help in creating a regional Red List of pollinators. Diversity assessments are conducted on 8 islands of the Aegean archipelago (figure 3), individually selected to collectively cover a wide geographical- and climatic gradient within the Aegean Sea and the Sea of Crete.
Figure 3: Overview of the project's fieldwork areas shown for different work topics.
Of all 33 European countries, Greece has the highest density of honey bee hives, and beekeeping in Greece is increasing. So far no study has addressed the question of whether solitary bee diversity is affected by competition from honey bees. Part of the POL-AEGIS project is to examine the effect of hive density on the foraging efficiency, reproduction, diversity, and pollination effectiveness of wild bees. The project also examines how plant-pollinator networks are infuenced by various grazing intensities, and this will result in valuable knowledge regarding pollinator conservation in Mediterranean regions with livestock, as well as allow for pasture management recommendations. A third aim within the POL-AEGIS project is to examine the impacts of fire on pollinator diversity, pollination services, and plant-pollinator networks. This part of the research will be conducted in areas that were heavily burnt within the last few years in Greece. The results are expected to provide new knowledge for making post-fire management recommendations.
The POL-AEGIS project will communicate its results in scientific articles, books, conference presentations, websites, and Greek popular science journals (e.g. Melissokomiki Epitheorisi -- Apicultural Review), and the project uses a scientific approach alongside community outreach. Researchers have the large task of systematic collection of pollinators throughout a very fragmented region, and this is taking place at an unprecedented scale. The results will be valuable for society at several levels. Locally, bee-friendly management will allow farmers to improve crop quality, help beekeepers to practice balanced apiculture, and provide a more holistic view of nature for wildlife conservationists and land managers. Regionally, the results of the POL-AEGIS project will provide baseline data useful for future monitoring and sustainable pollinator conservation.
LINK to Nieto et al.'s 2014 article, prepared by IUCN (International Union for Conservation of Nature), and published by the European Commission.
LINK to Petanidou et al.'s 2013 article in Journal of Apicultural Research.
