Bee deaths: At the forefront of the crisis swarm

World Bee Day last week was not celebrated again, negative headlines dominated.

A recent study led by the Martin Luther University in Halle-Wittenberg reported that a dangerous variant of the deadly crippled wing virus was on the rise worldwide.

DWV-B, as the variant is called, can now be detected on all continents except Australia and is already the dominant genotype in Europe.

"Exactly what we have experienced with the corona virus in recent years is happening in the world of bees," says Würzburg bee researcher Jürgen Tautz.

"Nature gives way and allows a new variant to emerge." According to Robert Paxton, first author of the study, it is only a matter of time before

DWV-B is said to be even more dangerous than the original crippled wing virus, which has been threatening bees since the 1980s and causes their wings to wither.

The virus is transmitted via Varroa mites and initially affects honey bees.

, the new variant is both more virulent and more easily transmitted

.

The virologists examined genetic data and publications on DW viruses from the years 2008 to 2021.

The new variant was also detected in wild bees.

According to Paxton, it is still unclear whether the threat to them is similar.

In commercially kept bumblebee colonies, the death rate from DWV-B has not yet increased significantly, he says.

It is now well established that the number of wild bees is generally declining.

Data come primarily from North America and Europe, but are also occasionally collected in South America, Africa and Asia.

"A decline can be observed everywhere," says Laura Breitkreuz, consultant for entomology at the nature conservation association Nabu.

Last year, a global meta-study was published for the first time that evaluated insect counts from the international biodiversity database GBIF.

Around a quarter of the masses of insects sighted before 1990 were no longer detected between 2006 and 2015, a team led by Argentine biologist Eduardo Zattara wrote in

.

According to the Red List, almost half of the more than 550 native wild bees in Germany are endangered, and 31 are even threatened with extinction.

Too many honey bees?

The honey bee, on the other hand, is not in danger.

Beekeeping is flourishing.

At the beginning of the year, the German Beekeepers' Association reported an increase in membership of 2.34 percent.

The number of beekeepers and bee colonies has been increasing steadily for over fifteen years.

So strong that the wild bees competing for food and flowers are threatened?

"In the case of wild honey bees, we usually observe population densities of just one colony per one to three square kilometers," says Tautz.

It could become problematic if the number of hobby beekeepers in urban areas increases so much that there is cut-throat competition.

The risk of transmission of diseases and parasites from honey bees to wild bees would then also increase.

"It always depends on the circumstances to what extent increasing honey bee numbers pose a threat," says Tautz.

There are studies

which show negative effects, but also numerous counter-examples.

The respective population densities and the local food supply are always important.