* Official checks at EU borders to be stepped up
* Risks to health, buildings and biodiversity
* EU ministers expected to endorse law in May
By Barbara Lewis
BRUSSELS, (Reuters) - The European Parliament backed a law on Wednesday to help keep alien species of plants and wildlife out of Europe and limit their spread in the event they do get in.
The new law seeks tougher border controls, to introduce an early warning system and to ensure rapid response and management of any invaders, such as tiger mosquitoes and demon shrimps.
Non-native plant and animal life are estimated to cost the European Union 12 billion euros ($16 billion) a year in damage and control costs. They compete with European species for food and disrupt their habitats. Some, such as Japanese knotweed, damage buildings. Others are a threat to human health.
The tiger mosquito, for example, a native of Asia, transmitted dengue fever and was linked to an outbreak of the chikungunya virus, which causes fever and severe joint pain, in Italy in 2007.
Some species have been introduced deliberately, by farmers, for instance. Others arrive accidentally, such as zebra mussels, which attached themselves to ships from the Black Sea in the 19th century. They can choke water intake pipes at power plants.
The European Environment Agency says more than 10,000 alien species have gained a foothold in Europe and at least 1,500 are considered harmful.
Environmental campaigners welcomed the parliamentary vote in Strasbourg as bringing in the first major new piece of EU legislation on biodiversity since an EU law conserving habitats was adopted in 1992.
The vote was "very positive," BirdLife Europe's head of EU policy, Ariel Brunner, said, but some gaps remained, such as allowing ships to dump ballast water, which is a major source of non-native species, at ports.
The law will require the 28 national EU governments to work together to detect invasive species placed on a list of high concern and coordinate measures to limit the damage.
The European Commission's original proposal suggested limiting the list to 50 non-native species, but members of the European Parliament called for a more flexible approach so any new threats can be quickly included.
EU ministers are expected to hold a final vote on the law in May and then it would take effect on Jan 1, 2015. The list of species of EU-wide concern would be drawn up by Jan. 1 2016.
$1 = 0.7234 Euros Editing by John O'Donnell and Larry King