Biological invasion

Gregerly Manyoki has strong allergic reactions to hogweed. When pollen season starts in Hungary, his throat, nose and eyes start itching.

"At the peak of the season it gets even worse," Manyoki says. "Then I start to cough, my eyes burn and my face starts swelling."

Manyoki is not alone. Many people in his country are highly allergic to hogweed. In fact, according to health authorities, around 15 to 20 percent of the Hungarian population suffers an allergic reaction when brought into contact with the plant. Throughout the last couple of years, hogweed has also begun to spread across many other EU states.

In Hungary, the weed is commonly found in corn and sunflower fields, where farmers are part of a high tech effort to eradicate it.

"If you come across the weed in your daily life it is easiest to just rip it out," says Tamas Kömives of the Hungarian Plant Protection Institute. "But when a larger area is infested then we take a picture and send it to our headquarters, who then take care of the issue."

The Hungarian Plant Protection Institute then sends helicopters to spray herbicides on the fields. According to Kömives, hogweed causes 100 million euros in agricultural damage each year in Hungary. Local farmers are being encouraged to harvest before the weed starts blooming.

Alien species in Europe

Hogweed is originally from North America and moved to Europe via contaminated farm tools and bird feed. It is one of over 1,500 weed types that now cause damage within the European Union.

The EU commissioner for Environment, Janez Potocnik, wants to coordinate future eradication of damaging plants between the bloc's member states. After all, the spread of harmful foreign plants, mushrooms, bacteria and animals doesn't stop at the borders.

"We want to stop invasive alien species before they take over the European Union and start causing problems," Potocnik said. "Member states need to identify the ways the animals are entering their territories and start developing action plans."

EU commission research has revealed that the yearly damage caused by the invasion of foreign pests into the bloc is 12 billion euros ($16 billion). There are currently 12,000 invasive species here, 15% of which are considered harmful. Now, the EU wants to make a list of the 50 most harmful pests.

"We have to manage the species which are already wildly spread in the European Union in order to stop the damage from becoming even worse," Potocnik warned.

The animal problem

Plants aren't the only problem for the EU - there are lots of animals causing issues in member states too. The black and white striped tiger mosquito is a native of Asia but is slowly making its way from Southern to Northern Europe. Its bites can transmit deadly diseases such as the West Nile virus.

Other alien species are doing harm to native European fauna. Zebra mussels consume valuable freshwater food used by native fish, for instance, while aggressive Asian hornets have been known to kill honey bees.

Larger animals such as the river rat, also known as the nutria, are causing problems in Europe as well. The 65 centimeter (25.5 inches) long rodent was brought to Europe because of its popular fur. When the demand for pelts decreased, the animals were simply released into the wild. Over the last few decades, these river rats have populated Middle and Southern Europe.

According to Francesca Marini, environment specialist for the Latium region in Italy, the rodents are a huge problem. "Nutria cause erosion at the canal banks, they make bridges collapse and cause floods too."

Time to act

In the case of the river rat, Italian authorities are taking action, but their efforts will be wasted if the animals just move on to France or Austria, experts say. Currently, the damage caused by nutria is believed to be around four million annually.

With its draft proposal the EU commission wants to come up with coherent European strategies for fighting the undesired migration of animals and plants. However, environment ministers and the European Parliament will first deliberate the draft proposal before any legislation can be approved.

According to Potocnik, the spread of alien species is the second most common reason for the decline of species diversity, right after the effects of humans. And, the problem doesn't just concern Europe. Alien species also migrate from Europe to other world regions and could potentially cause problems there, too.