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Disease vector: sterile males for the fight against tiger mosquitoes


Flying security risk: Tiger mosquito transmits dangerous infectious diseases
Scientific studies have shown that various tropical mosquitoes have spread in Germany in recent years, including the Asian tiger mosquito. The insects can transmit dangerous diseases. Now sterile males are said to help fight the mosquitoes.

Asian tiger mosquito is a security risk
Although mosquito bites are generally harmless in Germany, mosquito species that can transmit dangerous infectious diseases have now been found in Germany. Especially the increasing spread of the Asian tiger mosquito is viewed with concern. This insect is considered a flying safety risk. Experts are now reporting that sterile males should help fight tiger mosquitoes.

Spread of several exotic mosquito species in Europe
"Favored by globalization and global warming, there have been more and more introduced, established and spreading of several exotic mosquito species in Europe in the recent past," wrote the National Commission of Experts "Mosquitoes as carriers of pathogens" last year in a recommendation for action.

"In many affected countries (e.g. Spain, Italy, France, Belgium, Holland), local or regional control measures are regularly taken to prevent the establishment and spread of the species and / or the transmission of pathogens," it continues.

As the dpa news agency reports, scientists are now testing the use of sterilized males in the fight against the Asian tiger mosquito in Germany.

The biologist Norbert Becker told the German Press Agency in Speyer that females who copulated with these males would have no viable offspring.

"The females become pregnant, but they are stillborn."

Becker is the scientific director of the local action group to combat the snake infestation (KABS) and director of the Institute for Dipterology, which fights the tiger mosquitoes.

Habitat of the tiger mosquito "flood" with sterile males
According to experts, the Asian tiger mosquito can transmit more than 20 types of virus, including dangerous variants such as dengue fever, which can be fatal to weakened people.

The animals have been common in Italy for a long time. From there they came to Germany on freight trains and trucks along highways in the past years.

According to Becker, there is now a plan to "flood" the animals' habitat - in addition to conventional control - with sterile males.

"We have to consider all possible ways to get rid of this little animal," said the biologist. "And there are no half-baked solutions, there is only a massive fight."

Hatching rate decreased by 15 percent
According to the information, the insects are sterilized in Bologna (Italy). The treated animals could still compete with wild males afterwards, "but the sperm is 99 percent not okay," explained Becker.

From there, the mosquitoes are brought to Germany and released - a total of eight times last summer. At the time, the hatching rate had dropped by 15 percent.

But that's not enough: "Combating plus reducing the hatching rate should, according to our calculations, lead to a population breakdown," says Becker. This year, therefore, the suspension started much earlier and the number of sterilized males increased.

It is currently still unclear whether enough mosquitoes can be bred and treated at all. This would be necessary, however, because a previous experiment showed that the use of too few animals is not fruitful.

In the dpa announcement, Becker recalled a project in the 1980s when 30,000 animals were abandoned, where a billion are believed to have hatched. "And you didn't notice anything at all." (Ad)

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