Visit from the tropics: Tiger mosquitoes discovered in Berlin-Treptow – Knowledge

After the Asian tiger mosquito was spotted in a garden colony in Berlin’s Treptow-Köpenick district, entomologist Doreen Werner called on the public to help. Citizens should send the mosquitoes they find in their area to the scientific project “Mosquito Atlas”.

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Biologist Werner of the Leibniz Center for Agricultural Landscape Research in Müncheberg (Zalf) in Brandenburg has led the project for several years with the aim of designing mosquito species living in Germany – and tracking newly migrated species.

Small, everyday and slow to fly

At the end of the summer of 2021, with the help of researcher Zalf, an Asian tiger mosquito population (Aedes albopictus) have been certified. For small, daily and rather slow mosquitoes, which can transmit a variety of diseases, even small ponds are sufficient for reproduction.

Stagnant water accumulations must therefore be prevented. Car tires, in which rainwater collects, are especially popular with mosquitoes. With their transport, mosquito species can be carried over longer distances.

The Berlin health administration has now taken action to prevent further spread to Treptow. To do this, all the possibilities for laying eggs must be removed, drained and cleaned. “In this way you can restrain the population relatively well, if not eliminate it,” Werner now told RBB. From rain barrels to water vases and flower vases to bird baths and blocked drainage, there are many places that can be used as breeding water.

The so-called BTI tablets can also be used for rain barrels. The biological agent destroys the intestines of mosquito larvae and kills them. There are also traps for eggs, larvae and adults. In places where mosquitoes are housed, you really have to “act,” says Werner.

Rising findings in Germany

Meanwhile, more and more discoveries of Asian tiger mosquitoes are appearing in Germany. Some specimens were sent to the mosquito atlas project in 2021 from the Berlin partition garden. All rain barrels and water tanks were inspected and specimens were detected at all stages of development.

This could mean that a stable population has emerged, the biologist explains. It is not currently known if this has managed to pass the winter, but it is likely. The tiger mosquito is active from mid-May.

This mosquito actually prefers tropical temperatures, long, cold, and cold winters prevent it from spreading. It was once not native to Germany, but that seems to be changing as global warming progresses.

How dangerous is mosquito bites? In Germany, mosquitoes are no longer as harmless as they used to be.Graphics: Der Tagesspiegel / Rita Böttcher

So far, the Asian tiger mosquito has been detected mainly in southern Germany: in Bavaria, Baden-Württemberg, but also in Thuringia and North Rhine-Westphalia. In 2021, the population was found in Munich and Fürth, Bavaria, among other places. There was also evidence in well-known places, for example in Frankfurt (Main), Heidelberg, Freiburg, Rhine Graben and Jena.

A discovery was already found in Berlin in 2017. There are still no reports from Brandenburg. The first examples of tropical mosquitoes were discovered in Germany more than ten years ago. In general, they have so far been found quite rarely in our country.

The mosquito surrounds its victims in herds

The Asian tiger mosquito has white stripes, surrounds its prey in flocks, pursues them penetratingly, and attacks again after only a few seconds, even though they have fled in fear. As with other mosquitoes, females need a blood meal to allow their eggs to mature. The lazy mosquito moves only a few 100 meters around its breeding area. It is mainly spread unintentionally by people who transport plants or objects in which it multiplies.

The tiger mosquito is known to carry a particularly large number of pathogens, including dangerous tropical fevers such as dengue, chikungunya, zika and West Nile virus. More than 20 microbes have already been found in mosquitoes. The mosquito, which is considered aggressive, prefers to bite several people in a row, which contributes to the spread of the disease.

However, for diseases to be transmitted, a person carrying the relevant virus must have been bitten in advance – which, at least in the case of tropical diseases in our region, is likely to be less common. However, there may be a probability if, for example, an infected person returning from a trip encounters this mosquito here, Werner explains.

In addition, tropical fever pathogens – other than Chikungunya – need very high temperatures to multiply. In October 2021, the first cases of Zika in Europe, which were transmitted by native tiger mosquitoes, were reported in southern France. This virus is especially dangerous for pregnant women, as it can lead to brain and skull malformations in the unborn child.

The help of citizens is invaluable

Zalf researcher Doreen Werner relies on public information to design mosquito species. “This knowledge is invaluable to us,” she says. If it receives information on where a particular mosquito species has arrived, it begins to monitor whether the population has settled – and whether intervention is needed.

So far, private mosquito hunters have sent more than 24,000 insects. There are about 50 different species of mosquitoes in Germany and about 3500 worldwide.

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