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The Atlas of the Wild Bees of Brussels, funded by Brussels Environment and implemented by the team of Prof. Nicolas Vereecken at the Agroecology Lab of the Université Libre de Bruxelles, aims to better define the diversity, distribution, abundance and needs of more than 150 species of wild bees encountered in Brussels and to produce a document freely accessible and summarising the state of current knowledge.

WildBnB is the acronym of 'Wild Bees and Brussels' and refers to the concept of Bed and Breakfast (BnB), as our wild bees need nesting sites (bed) and host plants (breakfast) to survive and thrive in our urban environments. 

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Stéphane De Greef
Project coordinator

Agroecology Lab

ULB, Campus de La Plaine

T: +32 (0)2.650.6081

E: stephane.de.greef at ulb.ac.be

© 2019 WildBnB - ULB Agroécologie

All images by Nicolas Vereecken except when mentioned

Discover the world of bees!

A brief introduction

When we talk about bees, everyone systematically thinks about the European honey bee (Apis mellifera), but did you know that there are nearly 400 species of wild bees in Belgium, and that half of them can be encountered in Brussels? From huge bumblebees to tiny solitary bees nesting in the ground or inside hollow stems, wild bees occupy play an essential role in the pollination of our native plants in natural ecosystems, parks, private gardens and vegetable gardens. Unfortunately, some of these species have not been seen for decades and many more are threatened with extinction because of the difficult living conditions in our urban areas.

Honey bees (Apis mellifera) on wax cells filled with honey. (© Nicolas Vereecken)

Nine different species of wild bees, illustrating their diversity in shape, hair and colours. There are about 400 species in Belgium and half of them may be encountered in the Brussels Region. (© Nicolas Vereecken)

Social and solitary bees

The most famous bee species, the honey bee (Apis mellifera), is a social bee that lives in colonies of tens of thousands of individuals nesting in an artificial cavity (a hive made by humans) or a natural cavity (i.e. a hole in a a tree).

A single queen (reproductive female) lays eggs in hexagonal wax cells that will be taken care of by an army of workers (sterile females).

 

At the same time, tens of thousands of workers are in charge of collecting pollen (proteins) and nectar (carbohydrates) from dozens of species of flowering plants and turning it into honey.

The larvae will feed on honey and pollen to grow before metamorphosing into workers or into males and founding queens that will leave the nest on a mating flight to found new colonies in other places.

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Most bumblebees (Bombus spp.), except cuckoo bumblebees, are social and live in colonies with a single queen and a few dozens to a few hundreds workers and males. Their nest is usually built in abandoned rodent burrows or under a stone. Some species of Lasioglossum also have social behaviors.

But this way of life in society is actually an exception to the rule of bees, because most species around the world and in Belgium are solitary bees! There are no queens or workers, just females and males like most other animals.

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For many of these solitary species, after emerging from the nest where they have developed, the male and female bees will mate and the female will work alone to build a nest in a gallery dug either in the soil (ground nesting bees) or in a hollow twig (cavity nesting bees), or even in empty snail shells!

The nest usually contains about ten cells (chambers) each containing one egg and a small reserve of pollen collected from a single species of plant (monolectic bee), several closely related plants (oligolectic bee) or a wide range of plants (polylectic bee).

After hatching from the egg, the larva will feed on the pollen reserve to ensure its growth and development, before metamorphosing into an adult. Most solitary bees will have one generation per year (univoltine bee) or two per year (bivoltine bee).

But some solitary bees are also parasitic: the females don't build a nest but locate the nests supplied by other species of bees, before entering and laying their own eggs like cuckoos! The behavior of these parasitic species is still often poorly understood.

Comparing European honey bees and wild bees in Belgium

Number of species

Lifestyle

Nest type

Diet

Host plants

Economic importance

Ecological importance

Population trends

European honey bee

1 species (Apis mellifera)

Social (one queen, many workers, males)

In cavities (man-made hive or tree hole)

Nectar for adults, pollen for larvae

> 100 plant species (wild or cultivated)

Crop pollination, honey, wax, propolis

Pollination of native plants*

Stable or increasing (domesticated species)

Wild bees

~400 species across 37 genera and 6 families

Solitary except ~20 bumblebees and some Lasioglossum

Ground-nesting or cavity-nesting in twig, snail shell, etc.

Nectar for adults, pollen for larvae

From 1 to >100 depending on species

Crop pollination

Pollination of many species of native plants

Many species experience a decrease in diversity and abundance while others have stable populations or see their range expanding.

Finally, the European honey bee is a species that probably no longer exists in the wild in Europe (IUCN). It is essentially domestic (managed by a beekeeper) or feral (escaped from a hive) and, although it is important for the economy (pollination of crops, production of honey, wax and propolis) and easy to observe, its abundance can negatively impact wild bee populations through competition for natural resources (nectar, pollen) and transmission of pathogens (bacteria, viruses, fungi and parasites).

Wild bees are very diverse and, although some species such as buff-tailed bumblebees (Bombus terrestris) or European orchard bees (Osmia cornuta) are resilient and adapt well to changes in land use (conversion of natural areas to agriculture or cities), many species are suffering from habitat loss and climate change. It is therefore essential to do more research on wild bees to assess their population trend, identify the causes of their decline and implement conservation actions for threatened species. The development of an atlas of wild bees in Brussels is one of the components of this research and conservation strategy.

So... Helping European honey bees is not a solution to the global pollinators decline?

Contrary to the narrative found on many websites, in newspapers, petitions and alarmist documentaries, the European honey bee (Apis mellifera), the most famous bee species, is neither declining nor at risk of extinction across the European Union, having growing populations (see chart). For more information about the honey bee in Europe, the European Commission has published a summary on the honey market in 2018.

The European honey bee has been domesticated, bred and selected by us for centuries to reinforce its docility, sedentary lifestyle, wax and honey production. It probably no longer exists in the wild in Europe and so-called 'wild' colonies found in Europe are, unless proven otherwise, always colonies escaped from apiaries or their direct descendants.

At odds with public opinion, the number of beehives reported by all member states in the European Union is on the increase for the last 15 years (figs in thousands of hives from 2004 until 2018).

Source: European Commission

number-of-beehives-notified-by-the-ms-la

Because of this, experts insist that European honey bees be considered as livestock, being easily bred and spread through an agricultural practice called beekeeping. This species has therefore an economic importance for its production of honey, wax and propolis, and its pollination services for certain major crops such as apple trees.

But it no longer has a place in natural ecosystems because each of their colonies, made of tens of thousands of workers supported by us (protection from predators, feeding, veterinary care) constitute an intense and aggressive competition for many wild bees.

Although the decline of pollinators, including many wild bees, is a huge concern nowadays, European honey bee populations are on the increase. The multiplication of beehives increases the pressure on wild pollinators, reducing their diversity and abundance.

Comparing bees and birds helps understanding the duality between wild and domestic bees. Scientists agree that biodiversity is declining rapidly and globally and, more locally, we are finding out that a majority of birds in our parks, gardens and natural environments are declining, with fewer birds from fewer species observed.

 

To fight against this decline in bird diversity and abundance, it would be strange to promote outdoor chicken farming, although they are also birds, widely popular and easy to breed. This domesticated species is obviously not part of our natural ecosystems, and its populations is part of agriculture, not nature conservation.


In addition, its mass introduction, instead of increasing the bird diversity of an ecosystem, would have negative consequences because our poultry would consume the same resources as many wild birds and could infect them with diseases and parasites.

 

The idea of ​​promoting chicken farming to help endangered wild birds makes us smile, but surprisingly the idea of ​​promoting the European honey bee to stop the decline of pollinators remains an extremely popular idea despite its lack of logic and scientific backing. We hope that the information provided on this website will help clarify this situation.

Installing chicken coops in our parks and gardens is not the answer to the decline in wild birds. Similarly, installing beehives is not the answer to the decline of wild bees and is actually part of the problem.