Stuttgart  - Fears of dangerous mosquitoes from Italy spreading across the Alps and fanning out to spread fatal disease are overstated, a leading academic entomologist said Tuesday.

The Asian tiger mosquito, scientific name Aedes albopictus, has become widespread in the Tuscany region and other parts of Italy since the 1990s and has been sighted in Germany. Striking in daytime, it bites rapidly before it can be swatted.

Claus Zebitz, entomologist at Hohenheim University in Stuttgart, told Deutsche Presse-Agentur dpa, "Even if it can spread dengue fever, which is dangerous and common in Africa, the risk in this country is very limited.

"One should not get unnecessarily hysterical."

Zebitz said a German was more likely to catch dengue from an infected acquaintance coming home from a tropical holiday.

The tiger mosquito, originally from Asia, has been spreading in many nations round the world.

The entomologist said the northwards spread of Mediterranean insects into Germany as a result of climate change was natural.

"If the climate in Central and Northern Europe keeps getting warmer and bitterly cold winters become a thing of the past, most insect species will extend their range," he said.

Insects were champions at adaptation. The world had 250,000 plant species, but 1 million insect species.

Insect invasions could only be resisted by acting fast.

"We have to respond to possible dangers very early to be on the safe side," he warned.

Other pest species headed north include the cotton bollworm (Helicoverpa armigera) which attacks tomatoes and the green citrus aphid (Aphis spiraecola) which is resistant to most pesticides. (dpa)