Swiss patrol borders to ward off mosquito menace

The authorities in canton Ticino have intensified border controls at key crossings with Italy to try to prevent a small insect with a nasty bite from entering Switzerland. The creature in question is the Tiger Mosquito.

The Tiger mosquito which originates in south-east Asia, established itself in Italy in the 1990s. So called because of the white stripes on its legs and thorax, the mosquito is an aggressive biter and very efficient bearer of disease.

Ever since the insect was sported north of Milan, alarm bells have been ringing in Switzerland’s southern-most canton. The authorities are now implementing measures to prevent its infiltration.

“We’re trying to set up a monitoring system along the Swiss border with Italy,” said insect specialist, Peter Lüthy, from the institute for microbiology at the federal institute of technology in Zurich.

“We are actually setting up traps with small containers filled with water and a piece of wood because we know that the tiger mosquito prefers this habitat to deposit its eggs.

“We are setting these up along the Swiss border and at places where we have lots of traffic in order to detect this mosquito.”

The flight range of adult tiger mosquitoes is limited. It tends to fly only a few hundred yards from its breeding sites. Biologists are agreed that the worldwide transport of used tyres is to blame for its spread.

“Used tyres have been traded for a decade or so very intensively around the world,” said Lüthy. “They fill very easily with water and once you have water in them, it’s difficult for it to get out. These mosquitoes – especially the larvae – live in that water and are transported with the tyres around the world.”

Unlike many mosquitoes, the Asian Tiger feeds during the day. Scientists are particularly concerned because it is a very efficient transmitter of numerous human diseases.

“It is a vector of viral diseases such as dengue, rheumatic fever and Japanese encephalitis,” said Lüthy. “These disease are not prevalent in Italy or in Europe but you never know when they will be imported along with infected persons.”

Once it’s established a foothold, the tiger mosquito has proved notoriously tricky to eradicate. Not only do the average females lay up to 150 eggs each every few days but they breed in anything that holds water – even in the tiniest amounts.

“It can also adapt very easily to different climates,” said Lüthy. “This has been shown in the US where the mosquito was imported with used tyres in Texas in 1985 and has now spread over 25 states.”

If the Tiger Mosquito lays its eggs in the traps set up along the Swiss border, canton Ticino will immediately inform the federal authorities as precautionary measures will need to be taken.

It is believed it may be possible to eradicate the mosquitoes if they are detected before they spread. Another option is to eliminate as many places as possible where the mosquitoes breed.

by Vincent Landon