Hybrid ‘SUPER-SLUGS’ to invade Britain’s gardens after population

From the Daily Express

By STUART WINTER

A RAVENOUS charge of 500 billion slugs could be just the start of the invasion on Britain’s gardens as experts fear a population boom of hybrid “super-slugs”.

Slug

GETTY. A ravenous charge of 500 billion slugs could be just the start of the invasion on Britain’s gardens

European slugs looking to mate with our native species are creating a tsunami-like population surge which is being described as Britain’s “real slug invasion”.

While our slugs are described as having a “no sex, please, we’re British” approach to reproducing, foreign invaders slipping into the country incognito have voracious sexual appetites.

They are only too happy to shack up with native species, producing new generations of so-called capable of adapting to the varieties of our weather while fighting off the natural parasites and pathogens that can control their spread.

The gruesomely named Spanish stealth slug has already been pictured producing hybrid offspring by mating with the UK’s common black slug.

Headlines about the advent of so-called “super slugs” growing to six-inches and capable of eating 40 times their own bodyweight have put gardeners on a war-footing. Slug killer sales are 28 per cent up this month, say high street stores.

For Dr Leslie Noble, Reader in Zoology at the University of Aberdeen, it is not the headlines about 500 billion slugs creating a slime wave but the biology behind the changing shape of gastropod reproduction on our shores that is of concern.

slug

GETTY.  Experts fear a population boom of hybrid “super-slugs”

Describing how headline numbers are not necessarily something to get in a lather over, Dr Noble explains what is behind the real slug invasion Britain is witnessing in an article for the Conversation. 

He writes: “What is more problematic is the progressive, sustained and perhaps less spectacular rise in numbers which, tsunami-like, is maintained for far longer, and spreads widely throughout the countryside. This is Britain’s real slug invasion.”

“The trigger seems innocuous enough in isolation: a few non-native slugs from continental Europe have accidentally been introduced.

GARDEN

GETTY. New generations of so-called ‘super-slugs’ are poised to invade UK gardens

“Several of these species have close relatives in the , so similar in fact that only specialists can tell them apart, and they can interbreed freely.

“Of course, many animals can create hybrids without presenting a threat, but what makes slugs different – and these hybrids so worrying – is their interesting and deviant sex lives.”

British slugs, adapting to a post Ice Age climate, took advantage of their hermaphrodite biology and have used self-fertilisation as an evolutionary strategy, while across the Channel gastropods capitalised on “La difference” and indulged in straightforward one-on-one sex,

Dr Noble said: “A downside of such continued close inbreeding – and mating with oneself is as inbred as it gets – is a rapid loss of genetic variability, and some British slug species eventually came to consist of almost genetically identical individuals.

“This meant they were more vulnerable to parasites and pathogens that could rapidly evolve to overcome their defences.

“Meanwhile, in continental Europe, slugs were becoming more diverse, as balmier weather meant parasites and pathogens were a bigger issue than finding a mate.

black slug

GETTY. The gruesomely named Spanish stealth slug has already mated with the UK’s common black slug

“These slugs tended not to self-fertilise, and were genetically highly variable. This made at least some of them more resilient to attacks from parasites – a possibility not afforded to the inbred British slugs.”

Dr Noble says these adaptions were not an issue until humans disturbed the natural order and began moving slugs back and forth across the Channel as stowaways in commercial products.

He said: “As a result of this, we’ve seen widespread breeding between British and continental species.

“These new hybrid ‘super-slugs’ are highly fertile, and their genetically diverse offspring are adapted to cope with both the British climate and parasites and pathogens, most of which remain in continental Europe anyway.”



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