Who What Why: Are British slugs under threat?

A "super breed" of slugs has arrived from Spain, but are they a threat to the UK's native slugs?

The wet weather has resulted in myriad problems for people around the country and now there is another - it has helped a "super breed" of slug from Spain flourish in the UK.

Numbers of the creature commonly known as the Spanish stealth slug, Arion flagellu, are growing fast in the UK - helped by the wet weather - and threatening native molluscs, say experts in the field.

Another Spanish slug, Arion vulgaris, has already become a huge problem in Norway, attacking farms and gardens. Researchers fear the same could eventually happen in the UK.

Why the Spanish stealth slug poses such a problem is its aggressive breeding cycle. It produces hundreds more eggs than native slugs and so numbers multiply quickly. It also brings with it new diseases and parasites which can kill British slugs.

"It is a real concern," says Dr les Noble, a slug expert from Aberdeen University. "I have been collecting and analysing data on slugs for 30 years and it is clear to me that this incoming species is getting a foothold in the UK and spreading."

Their aggressive breeding cycle mean they lay around 400 eggs in a year, compared to the 100 or so laid by native species, says Dr Noble. Another problem is the diseases and parasites the slugs - which can grow to 10cm - carry.

"The Spanish stealth slug has evolved to deal with these diseases and parasites," says Dr Noble.

Continued:  http://www.bbc.co.uk/news/magazine-18672728