ENVIRONMENT

The invasion of the winged insects

Spain is suffering a rapid increase of tiger mosquitoes and Asian wasps As a result the bee population is under threat, while the risk of disease is rising

Researchers from the Mosquito Control Center in Baix Llobregat (Catalonia) look for tiger mosquitoes at a traffic stop.
Researchers from the Mosquito Control Center in Baix Llobregat (Catalonia) look for tiger mosquitoes at a traffic stop.

The discovery of a huge nest of Asian predatory wasps forced organizers to cancel a music concert due to be held last week in Bilbao. Recently, none of the precautions being taken to combat these “killer wasps” – so-called because of the speed with which they can devour a bee – are proving sufficient to tackle their rapid spread across northern Spain.

The species entered the country in 2004, and since then there has been no stopping it. Together with the tiger mosquito – which this summer was responsible for a man in the Valencia region becoming the first recorded patient to contract the chikungunya virus in Spain – the invading species is of increasing concern to experts as a result of its ability to occupy territory at a speed that makes it apparently impossible to stop.

In the case of the wasp, the insects may have arrived in a container transporting ceramics from China

“These two species are non-indigenous invaders, which means they do not belong to our fauna, and have been introduced by man,” explains Eduardo Galante, a professor of zoology at the University of Alicante. In the case of the wasp, it is thought that the insects may have arrived in a container transporting ceramics from China to France. Scientists also suspect that the tiger mosquito arrived in Spain through imported merchandise. Their ability to adapt did the rest.

“Climate change is having an effect on the expansion of these species,” explains Galante, who is also the president of the Spanish Association of Entomology. “Given that temperatures are higher, there are species that are surviving in places where they weren’t able to live before.” This is what may have happened with the tiger mosquito, which is now living along much of the Spanish coast. “They can get as far as the center of the peninsula, which is drier and colder, but they first have to make it through very dry and arid areas.”

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The Asian wasp, Vespa velutina, has spread from France into the Basque Country, part of Cantabria and Portugal. It doesn’t transmit any diseases, but beekeepers are particularly concerned about its spread, given its ability to annihilate native bees. The wasps wait outside beehives, causing the bees to stay inside. As soon as they leave the hive, the wasps catch them in flight and devour them.

Given the lack of food this causes, the queen bee stops laying eggs, and “the bees end up dying” without any replacements to guarantee their survival, explains the former president of the beekeepers’ association in Gipuzkoa, Julian Urkiola. “There are still bees, but they die in winter,” he continues. “The European Union has to start helping with research. There are a number of laboratories that are working on the problem here […] but there is no effective result.”

The European Union has to start helping with research. There are a number of laboratories that are working on the problem but there is no effective result”

The nests were first found on the coast, but have now moved into many inland areas, Bizkaia, parts of Álava and the Cantabrian coast. Beekeepers are having to move hives to altitudes above 1,000 meters in order to avoid attacks, and some of the wasps’ nests can measure up to a meter across. “They are getting bigger all the time and their voracity is astonishing,” Urkiola explains.

In Gipuzkoa around 300 nests have already been destroyed, while in Bizkaia two are dealt with every day. Last year a total of 773 were removed in Gipuzkoa alone, and the figures look like they will hit record levels this year.

As for the tiger mosquito (Aedes albopictus), high temperatures this summer are thought to have contributed to its spread. According to zoology professor Eduardo Galante, this species is now here to stay. “We are just going to have to live with them,” he says.

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