# Alien invaders hit the UK



## kyektulu (Oct 13, 2008)

Taken from BBC News:

*A superweed spreading throughout the UK could be brought under control by introducing plant-eating predators from Japan, scientists believe.* 
Japanese knotweed was first introduced as an ornamental plant, but has since plagued the environment; removal is costly and time consuming. 
Now a team has identified natural predators from its native home that could also control it in the UK. 
The plans have been submitted to the government for approval. 
If the proposal gets the go-ahead, it will be the first time that biocontrol - the use of a natural enemy to control another pest - will be used in Europe to fight a weed. 
All this week, BBC News will be taking a closer look at some of the alien invaders that are in the UK. 
*Appetite for knotweed*

This year has been particularly bad for knotweed spread in the UK. 
James MacFarlane, vegetation adviser for Cornwall County Council, said: "The weather patterns have ended up with us seeing a lot of knotweed spread in a number of areas." 
In Japan, the original home of knotweed, the plant is common but it does not rage out of control like in the UK. 
Dick Shaw, the lead researcher on the project, from Cabi, a not-for-profit agricultural research organisation, said: "In 2000, we went out to Japan to see whether the plant had any natural enemies that it had lost when it came here. 
"We found that it had a lot: there were 186 species of plant-eating insects and about 40 species of fungi." 
The team then began to test the predators to find those that only had an appetite for Japanese knotweed - and not any other plants. 
The researchers tempted them with plant species that were very closely related to knotweed, less closely related species that belonged to the same tribe or family, and important UK plants such as apples and wheat. 

Those that attacked any plants other than Japanese knotweed were ruled out, explained Dr Shaw. 
Eventually, the list was whittled down to two: a sap-sucking psyllid insect (_Aphalara itadori_) and a leaf spot fungus from the genus Mycosphaerella. 
Dr Shaw told the BBC: "We have done some efficacy trials here in the lab and they are showing a significant impact
Successful biocontrols do not eradicate the target weed - this would mean wiping out their only food source and effectively making themselves extinct - but they do bring them under control. 
Dr Shaw said: "The psyllids are having an effect on the plants' height and the treated knotweeds produce tiny curled leaves rather than big light absorbing leaves, which means that less resources will get to their root system. 
"The nymphs are literally sucking the life out of the plant," he added. 
*Phenomenal growth* 
Japanese knotweed, like many other non-native, invasive plants, was first introduced to the UK for horticulture. 
 	   #aiknotweedrh_obj { 	float: right; }           
Its 3-4m-tall (10-13ft) stems, ornamental leaves and clusters of white flowers made it an attractive option for gardens. 
Simon Ford, a nature conservation adviser from the National Trust, said: "Japanese knotweed first came into the UK in 1840 through Wales - but it was only about 10 to 15 years later that people started to see it as a threat." 
The plants grow incredibly quickly - some have been shown to grow four metres in just four months, they can spread at a tremendous rate, and they can quickly obliterate any other vegetation growing nearby. 
Mr Ford said: "By the time they realised this it was already far too late." 
Today, Japanese knotweed is prevalent throughout the UK. 
It has not only caused great damage to plant biodiversity but it is also causing problems for hard structures, including buildings, paving stones and flood defence structures. 

It has been estimated that to remove all knotweed from the UK would cost several billion pounds. 
Cabi scientists believe that natural control could offer a much simpler solution. 
The project has cost about £600,000 over five years. 
Dr Shaw said: "In comparison to the current control methods, if it works, this will be significantly less costly." 
The team has submitted its proposals to the government. 
The Department of Environment, Food and Rural Affairs (Defra) along with independent peer reviewers will assess the work before it is submitted for a public consultation. 
Dr Shaw said: "We do not know if this is going to be the silver bullet for knotweed, but if we were able to just stop the thing spreading at the rate it currently is, or make it easier to kill, I will be very happy." 
The research project has been paid for by a consortium of UK sponsors including Defra, the Environment Agency, the Welsh Assembly Government, Network Rail, South West Regional Development Agency and British Waterways, coordinated by Cornwall County Council.


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## kyektulu (Oct 13, 2008)

Now I dont know about you, this sounds all well and good but I cant help harbouring doubts that introducing another unnative species could end up causing more harm that good...


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## Nik (Oct 13, 2008)

*Kudzu & Billy Goats...*

Um, apparently the US Kudzu problem has been turned on head by serendipitous discovery that the common-or-garden 'Billy Goat' can eat it faster than it grows-- And thrive on the stuff.


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## kyektulu (Oct 13, 2008)

Maybe we should all have a goat instead of a dog then... lol


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## Urien (Oct 13, 2008)

I was out running tonight, and I swallowed a fly. Blurgh. So when I got home I thought, better get shot of the little critter, so I swallowed a spider. But you know what? It wriggled and tickled and.....


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## Rosemary (Oct 14, 2008)

It does sound good, Kye but as you point out,it could end up causing more harm that good. 

Australia has many introduced species, to help eradicate other introduced species which have become 'out of control', so I really hope that the UK scientists have a good look into this 'natural predator' before introducing it.

What will this 'predator' eat once the Knotweed has been eradicated? Will it target another plant but this time a native plant?   

We are now battling to control the Cane Toads which were introduced for similar reasons.  Many of our rivers are clogged with introduced plants or our fish are declining due to the many exotic fish which have found their way into the river systems.


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## ktabic (Oct 14, 2008)

Rosemary said:


> What will this 'predator' eat once the Knotweed has been eradicated?



Will the predator even bother with the Knotweed - or will it find some native species more palatable?


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## Drachir (Oct 14, 2008)

We have the same problem here (Western Canada) with a plant called Eurasian Milfoil (Myriophyllum spicatum).  The solution seems to be to bring in the milfoil weevil.  Since the weevil eats only the plant in question and dies out when the plant is eradicated it does not pose a problem.  There is a similar problem with a plant called Purple Loosetrife (Lythrum Salicaria) and a beetle has been introduced to combat that as well.  So far there have been no reports of great success, but I do remember that the Australians dealt successfully with the problem of prickly pear by bringing in an insect that eats that plant.  The key factor is to make sure that the imported insect feeds only on the problem plant and nothing else.


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## David Gullen (Oct 14, 2008)

Call me a traditionalist, but isn't the usual name for a plant predator 'herbovore'?
*
On Discovery Channel tonight - Nature's Deadliest Plant Predators*

"Nimble and deadly, the cow is one of nature's most deadliest plant predators, trampling grass and clover into submission with its mighty hooves and tearing living tissue from the helpless plants with it's merciless ruminant jaw.
Oh, it poos on them too."


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## Drachir (Oct 14, 2008)

Herbivore actually.


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## David Gullen (Oct 14, 2008)

doh!


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## Urlik (Oct 14, 2008)

I suppose you could class cats as plant predators............

cats have been known to lie in wait for hours, holding off for the perfect moment to spring the trap.
I have also seen cats stalking garden plants.


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## Nik (Oct 14, 2008)

And cats will torture helpless wind-blown leaves until your heart goes out to them...

( The rockery mice are staying in their bunker until dusk... ;-)


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## Sephiroth (Oct 15, 2008)

Judging by the damage my sister's kittens have done to two of her house plants.......



In all seriousness, do their 'efficacy trials' really guarantee that whichever of the two species they select won't devlop an appetite for something else they haven't tested?  

Seems like a bit of a gamble to me.


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## Wybren (Oct 15, 2008)

Rosemary said:


> It does sound good, Kye but as you point out,it could end up causing more harm that good.
> 
> Australia has many introduced species, to help eradicate other introduced species which have become 'out of control', so I really hope that the UK scientists have a good look into this 'natural predator' before introducing it.
> 
> ...



My thoughts exactly Rosie, How often have we seen things get introduced because they were thought to be a good thing when in the end they have just become a pest themselves.

My mum used to head the Landcare in my hometown and I remember them spending years trying to get rid of the Bitou Bush there. I think they did succeed but it took a lot of effort and if the people who introduced it looked hard enough, they could have found Australian Natives that do just as good a job of holding dunes together as the Bitou bush does.

Hopefully this plant that they are looking to introduce only feeds on the Knotweed and does not become a pest.


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## Precision Grace (Oct 15, 2008)

It's exceedingly foolish in my opinion. You just have to look at New Zealand and Australia to see what manner of damage any introduced species can cause. Best come up with some local solution I would have thought.

And now crustaceans are at war..

Excerpt - sorry not allowed to post link
*Alien crustaceans clash claws in UK waterways*

Posted in Biology, 15th October 2008 09:20 GMT
  Scientists believe the UK ranges of two aggressive alien crustaceans - the North American signal crayfish and the Chinese mitten crab - are beginning to overlap, offering the prospect of an epic battle for supremacy over Britain's waterways.
  ---

  The signal crayfish poses a particular threat to "native aquatic plants, invertebrates and fish through direct predation", but also carries the fungal disease crayfish plague _(Aphanomyces astaci)_, which could ultimately wipe out our own white-clawed crayfish _(Austropotamobius pallipes)_.
  Ecologist Stephanie Peay, describing the immigrant crustaceans as "aquatic thugs", told the BBC: "The plague does not seem to harm the non-natives, but if our native white-clawed crayfish encounter it, they die within weeks."
  She added: "Where the non-natives move in, the white claws are lost. Survey work has shown that it only takes between four and seven years from first arrival to achieve a complete local extinction. The only future for the white claws is in isolated water bodies that are completely free from non-native crayfish."


---


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## Sephiroth (Oct 15, 2008)

This is an unavoidable consequence of climate change, unfortunately.



Unlike the deliberate introduction of non-indigenous species, it can't be stopped. 

We've changed the world, and there's no putting it back to the way it was.


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## kyektulu (Oct 16, 2008)

ktabic said:


> Will the predator even bother with the Knotweed - or will it find some native species more palatable?



Hmm excellent point... I vote no to the new bug.


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## Pyan (Oct 16, 2008)

ktabic said:


> Will the predator even bother with the Knotweed - or will it find some native species more palatable?



As it says in the report...



> The team then began to test the predators to find those that only had an appetite for Japanese knotweed - and not any other plants.
> The researchers tempted them with plant species that were very closely related to knotweed, less closely related species that belonged to the same tribe or family, and important UK plants such as apples and wheat.
> 
> Those that attacked any plants other than Japanese knotweed were ruled out, explained Dr Shaw



Quite apart from smothering other, native, plants with its rampant growth, and being almost impossible to kill by any normal means, this thug of the plant kingdom also poses another threat in this country, in that no native insects or animals will eat it, thus causing huge swathes of land to become wildlife desert..

I speak from experience - I've been trying for _five years_ to get rid of an area of knotweed at work, about 10m² worth. Multiply that by the effort needed to even keep it under control, let alone eradicate it, and it gets to the point when any new method of control has to be at least considered and tried...


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## ktabic (Oct 17, 2008)

So the predators they have selected won't attack any other plant - for now. But when they release said predator into the wild in a new environment, the pressures on the them change. That can lead to wildly different responses from the predators, compared to the lab conditions they are currently in. 

Then there's what will the predators do if they are successful? Just die out is a possiblilty, but as knotweed dies out they will be under pressure to expand their eating range.

At this moment in time it's not worth the risk, they aren't even sure it will work. More research is required, on a larger scale, over a longer period of time (five years is not very long in the lifetime of a species).
More time will also let them figure out how to deploy the predators.


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## Pyan (Oct 17, 2008)

ktabic said:


> More research is required, on a larger scale, over a longer period of time (five years is not very long in the lifetime of a species).



Agreed - but equally, it's far too short a time for a species-dependent predator to change from knotweed to another plant - especially as the whole point is that knotweed is so different from our native plants that none of our native plant-eaters have started eating it even after nearly 170 years.


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