Mosquito numbers rising as Germany warms up | Environment| All topics from climate change to conservation | DW | 18.07.2013
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Mosquito numbers rising as Germany warms up

Thanks to mild winters and moist air, mosquitoes are thriving in Germany. And not just the native species. Scores of exotic mosquito types are now moving here and the unwanted visitors are bringing dangerous baggage.

Close-up of a mosquito biting a human Photo: Birgit Betzelt/actionmedeor/ef +++(c) dpa - Bildfunk+++

A mosquito bites

More and more species of exotic mosquitoes are arriving in Germany and with them the amount of dangerous infectious agents is rising, such as bacteria or viruses. Many of the mosquitoes hitch a ride on tourists or business travellers around the world before arriving in Germany.

Although they tend to survive for only a limited time and die out during the cold winter, experts say the climate in Germany will get warmer and the winters will shorten, meaning their numbers are set to continue to increase.

"The average temperature in certain regions is relatively high, and it's also getting wetter," says Sven Klimpel from the Senckenberg Gesellschaft für Naturforschung, a group of research institutes and natural history museums in Germany which conduct research into bio- and geosciences. "Those are ideal conditions for mosquitoes."

But it's not only the exotic pests causing scientists to worry. Native mosquitoes find the change in conditions equally appealing and are producing several generations of offspring each year.

Dangerous discoveries

Klimpel and Egbert Tannich, from the Bernhard Nocht Institute for Tropical Medicine in Hamburg, are currently researching infectious diseases being spread by mosquitoes in Germany.

The two scientists have already identified the Asian bush mosquito, the Asian tiger mosquito, and the yellow fever mosquito here in Germany. In an extensive 12-year study, the researchers collected more than 75,000 mosquitoes from 55 locations throughout the country. They discovered about 50 native and exotic mosquito species.

Undated closeup photo of an Asian tiger mosquito (Photo: Stephan Jansen)

The Asian tiger mosquito, which has now been spotted in Germany, transmits dengue fever

"We have found that in certain regions, there are non-native mosquitoes that have made these regions their home, and there are others that only appear every now and then," Egbert Tannich told DW.

Their reseach also found lava from the dirofilaria repens, a parasitic roundworm, in German mosquitoes for the first time. The parasite is native to Africa, Asia and southern Europe. The worm lives in the hearts of dogs and foxes. If a mosquito were to suck the blood of an infected animal, it could transmit the infection onto its next victim.

For humans the resulting infection is relatively harmless, as the worms die off quickly. Nevertheless, it's important to observe these sorts of problems before they become a health issue here, says Sven Klempel.

A question of sex

Male mosquitoes are mainly harmless. They feed on plant sap, and the only thing they're really interested in is fighting for the favor of females. Male mosquitoes also don't bite humans.

"You can recognize them by their bushy antennae," says Sven Klimpel who admits that, in his opinion, "the only good mosquito is a dead mosquito."

After sucking blood from an unsuspecting victim, female mosquitoes can almost double in weight however. Each meal totals between two and five millilitres, enough to provide important proteins to its eggs. This is how the offspring thrive.

After feeding on one host and moving to the next, mosquitoes can transmit viruses, parasites or worms, and worse - diseases such as malaria, sleeping sickness, dengue or chikungunya fever.

Most infectious agents are native to Africa, Asia or Latin America - regions with warm, humid climates. As temperature increases in Germany though, the scientists say that the infectious agents in mosquitoes here will multiply faster.

"In the next 10 to 50 years, infectious diseases transmitted by blood-sucking insects will increase in Europe - especially in Germany," Klempel told DW.

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