‘One third of bees depend on one plant’

One third of our wild bee species are threatened with extinction. Through pesticides, vigorous mowing and competition with the honey bee.

On Sunday 22 May, International Day for Biodiversity, four species of bumble bees roamed our uncut garden: earth bumble bee, field bumble bee, stone bumble bee and meadow bumble bee. Identifying solitary bees did not go smoothly – the insects rarely sit still long enough to take a clear picture of them. Nevertheless, some beautiful species appeared, such as eyelash-flank sand bee, great woolly bee and wallpaper bee.

‘The last two are bees from flower edges and not from lawns,’ says Jens D’Haeseleer from Natuurpunt, one of the biggest bee experts in our country. “It can have a big effect on wild bees if you don’t mow a lawn in May. Dandelion is one of our most important bee plants and flowers primarily in May. The field thistle is also a wild plant that is desired by bees and which can end up in uncut gardens just like the piglets. You do not have to bet on rare plants for a diverse bipopulation. The best bee plants are common endemic species, such as clover and ivy. ‘

Green garlands with bee-friendly climbing plants like wine over narrow streets can connect facade gardens.

D’Haeseleer hopes the ‘Don’t Mow’ campaign is over Crack will be a step towards less intensive lawn care throughout the year, and not just in May: “If one continues to mow systematically in April and June, the effect of omitting lawn mowing in May on wild bees will be limited. Many solitary bees fly for a limited period of about a month, after which they go to sleep. You can cause local problems for them through excessive mowing. ‘

spit bee

In 2019, D’Haeseleer and a couple of colleagues listed 403 bee species for Belgium. Some have cheerful names, such as the sparrow bee and the tabby bee. About half of the species are in danger of extinction. There are bees with such a specialized lifestyle that there is little chance that they will survive with us. An example is the ericabia, which occurs only in the northernmost tip of the Kalmthoutse Heide and lives exclusively on heath. Its habitat is under great pressure due to dehydration and eutrophication.

‘The fact that there are so many bee species is related to the fact that many species have their own niche,’ explains D’Haeseleer. ‘One third of our bees depend on only one plant species for their survival. It’s a way to avoid competition. In addition, nearly a hundred of our bee species are true cuckoos that are parasitic on other bees, often just one species. Excessive specialization can cause problems for species in a landscape that is becoming less and less diverse. As a result of global warming, a few new bee species are added each year. Most of them seem to have come to stay. But where climate types emerge, others disappear ‘.

Bees are real sunbathers, so many species will benefit from the warming. But besides heat, they also need food and shelter, and that is less obvious. No less than 80 percent of our bees nest in the ground, which nuances the importance of the increasingly popular bee hotels. ‘They are only useful for 5 percent of our species,’ says D’Haeseleer, ‘and then they must be made well and placed – a house without food nearby is useless. Many solitary bees rarely fly more than a few hundred meters from their nest. Sandy spots in an uncut lawn are better side hotels than wooden structures. A naturally run lawn is the largest bi-hotel available. ‘

Black beers. © Getty

Bees are known to be providers of useful ecosystem services to humans, not to mention the honey produced by domestic honey bees. For our country alone, bees provide an estimated economic added value of 252 million euros a year by fertilizing mainly fruit and vegetables for free. Not everyone is well aware of this. Not infrequently, fruit growers mow daisies and dandelions away between their rows of trees, leaving bees without food after the flowering season. The use of pesticides is, of course, always and everywhere catastrophic.

Bees can also thrive in cities. Every year, on the occasion of Bee Week, the Flemish Government’s environmental department awards a prize to the most friendly municipality. This year, Ghent received the award for a large municipality, and Diksmuide for a small one. Urban ecologist Andreas Demey is the architect behind Ghent’s acclaimed by-policy. “Of course, we aim to cut parks and roadsides as little as possible,” Demey explains. ‘But at the same time we are committed to achieving the widest possible flowering arc for bees. This means that flower sources must always be available to feed bees. ‘

Cemeteries

The city’s landscape gardening department also organizes its cutting policy in such a way that there are spots everywhere that can function as shelters – it is useful for biodiversity that not everything is beaten at once. Special areas such as cemeteries or old railway ramparts that connect parks and other landscapes receive extra attention. The cemetery in Gentbrugge, Ter Durmenpark and Westerringspoor between the station in Gent-Sint-Pieters and the district Wondelgem are examples of this.

“Urban green has long been underestimated, but it can play a big role as a carrier of biodiversity,” says Demey. ‘Some urban biotopes, such as parks and cemeteries, are old and may serve as replacement habitats for certain species. Attracting pollinators is certainly useful for the many kitchen gardens in and around the city. We also take smaller initiatives to connect areas, such as green garlands, that run on cables across narrow streets from one front yard to another. We hang bee-friendly climbing plants like wine or honeysuckle on it. We can hardly keep up with the number of requests for this. When we sow mixtures, we primarily focus on the long term. We must avoid creating an ecological trap for bees by luring them to a bed of annual flowers that will no longer be there the following year. ‘

Demey emphasizes that he is not the big proponent of placing hives in urban nature, for honey bees can compete with wild bees. There are probably no more wild honey bees in Flanders. The honey bee has become an agricultural product – it also falls within the area of ​​competence of the Ministry of Agriculture. Some describe honeybees as ‘six-legged cattle with wings that graze wherever they get the chance’ – in this view beekeepers are farmers without pastures. Others see hives as a variant of bird nesting boxes that hardly anyone overturns.

Keeping honey bees because wild bees fail is like raising chickens because bird populations are declining.

Beekeeper Dylan Elen works as a beekeeper at the Swiss agricultural institute Agroscope and wants a more nature-friendly honey bee management. Along with a number of like-minded people, he is engaged in a return of the black bee: the subspecies of the honey bee, which originally lived in our region but has been completely displaced by cultivated varieties, mainly from the Balkans. “There are still colonies of wild black bees near Chimay in Wallonia and on two Dutch Wadden Islands,” he says. ‘We have started a project to reintroduce a few swarms of them into the Limburg nature reserve Bosland with the support of the Agency for Nature and Forestry (ANB). Wild honeybees make their nests mainly in hollow trees, which have become rare in our exaggerated landscape. But in Bosnia there are many abandoned nesting sites of the plaice, which are suitable for the black bee. The main problem will probably be to avoid hybridization with alien honey bees. Queens and handrons fly miles from their nests to mate. ‘

Independent at

Elen even works with black bees: ‘To me they are not tame, like other honey bivariates. Even in difficult times, they keep doing their thing, which is good because I’m a pretty lazy beekeeper. Many beekeepers think that the black bee is too aggressive to be handled, but I can attest from ten years of experience that this is not the case. She is more independent than the other breeds. When beekeepers in the summer of 2021 had to actively support their bee colonies due to the heavy rain to prevent them from starving due to lack of food in the area, this was not the case for my black bees. They drew up their plan. ‘

Elen hates the argument of many beekeepers that they should focus on honey bees to compensate for the loss of wild bees: ‘We must first help, not replace the solitary wild bees and bumble bees. Due to the chronic nitrogen pollution of our landscape, many food plants for solitary bees are under pressure. Unlike many solitary wild bees, honeybees are true generalists who move from one flower offering to another depending on availability. It increases their chances of survival. ‘

The Dutch counterpart to our ANB, Staatsbosbeheer, has decided that there will no longer be hives in nature reserves unless it is unusual (and then only with the black bee). Elen recognizes that there may be competition between honeybees and wild bees, but not always and everywhere: ‘Honeybees like to go after mass-blooms that suddenly provide a lot of food, such as willow trees in the spring or a street full of fake Christthorn trees . Then they are not interested in plants like stork beak or poppy, which wild bees feed on. But if the big vendors temporarily disappear, there could be competition with solitary bees. ‘

Bee expert Jens D’Haeseleer from Natuurpunt is also a tough lover of the honey bee, especially in nature reserves. “Keeping honey bees because wild bees are not doing well is like breeding chickens because bird populations are declining,” he says. “The honey bee is the least endangered bee in the world, so it does not necessarily need much attention.”

D’Haeseleer: ‘It has been estimated that no less than 110,000 solitary bees can live on the nectar and pollen needed to feed a honey bee colony of 50,000 individuals. If beekeepers want to do something for nature, it would help if they aim for more natural densities of their animals – now our landscape is sometimes flooded with honey bees. You are not going to spend a hundred cows per day. hectares for grazing management in nature reserves. But if you let honeybees do their own thing, with nest caves they’re looking for themselves, you’d get a different story. But most beekeepers do not like to hear that. “

For information on the black bee, see www.ZwarteBij.org. June 25 is an introductory day in Limburgse Bosland.

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