Bio-control of Knotweed

Have a look at this:

http://news.bbc.co.uk/1/hi/sci/tech/8163730.stm

Basically, in an attempt to control Knotweed in the UK, there are plans to intriduce a new insect into Britain that only feeds on Knotweed.

What do we think?

Personally, I wonder if this is another example of us not learning from our past mistakes. It was a mistake to intriduce Knotweed into the country in the 1800s, when it was introduced without much thought for how it might affect our ecosystem. Could it be another mistake to make a man made change to our eco-system by introducing a non-native insect? Or perhaps a bit more thought went into this and it might be ok.

I am always a bit skeptical about things like this, as there are numerous examples of mankind's meddling upsetting the balance. In Australia Gorse was introduced as an excellent heat and drought tolerant livestock proof hedge, and it took over. There was also an incident involving some introduced toads that were supposed to polish off a pest, did so and then started causing all sorts of problems for other wildlife. That's just a couple of examples, I'm sure there are more.

But then we do live in changing times. Something has to be done about Knotweed swamping out our native plants and upsetting diversity. We can't carpet bomb the whole country in glyphosate, and we can't just ignore the problem.

So, what do we reckon?

 

This would of been extensively thought out and I'm sure they've run tests with UK plants from the same family & genus to make sure that it will only feed on Japanese Knotweed and Knotweed alone

this has been the ultimate plan for a number of years they were (still are?) also considering introducing other insects which feed on the roots and storage organs of the knotweed...

 

Yes, I did hear about this on the news this morning. The person interviewed insisted that the control bug has undergone extensive testing and poses no threat to the wider ecosystem. However, as we all know it is impossible to reproduce the outdoor environment, with all it's diversity, in controlled laboratory conditions, as the Law of Unintended Consequences has already demonstrated, to our cost.
I also worry about the the rest of the polygonum/persicaria family, a lot of which are garden ornamentals and even some native wildflowers. I would be sad to lose those.

 

clueless1 and Blackthorn

I share your misgivings. This idea of introducing a species for a specific purpose is fraught with danger. Too much is uncontrollable in the wild. Evolution takes over!

 

I must ask what happens when the bug has eaten all the Knotweed ???

 

Apparently it does not eat all of the knotweed, just weakens it so that it is easier to deal with.

 

More info here too:
http://www.guardian.co.uk/environment/2009/jul/23/japanese-knotweed-bug-control

 

..and here:
http://www.cabi.org/japaneseknotweedalliance/default.aspx?site=139&page=356

 

There are not many creatures on earth which deplete there entire food source as this would be devastating for there species as a whole:thmb:

 

Most species would devastate their own food supply if they were allowed to do so. Nature deals with that issue by having a fine balance of predator and prey.

Consider the rabbit for instance. They breed at an alarming rate and will eat just about any vegetation there is (barring stuff that is poisonous to them of course). Taking humans out of the equation (as we probably have the biggest impact on nature), if it wasn't for various birds of prey, foxes, weasels etc, nothing would control their numbers, and with the rate that they breed, there would very soon be too many rabbits for the amount of available food, so they would decimate supplies until they all starved to death.

People have a massive impact on the natural environment, but we can't oversee everything. We don't even really understand most of it if we're honest with ourselves. That's why I personally have misgivings about this non-native insect being introduced to control the Knotweed.

It has been said that lots of thought will have gone into this, but I'm also skeptical about how thorough academics can be. I have always believed that there are two kinds of expert in any field. There's the one that's read all the books, done the lab experiments, listened to speeches by top profs etc, and then there's the old guy with weather beaten skin and arms like tree trunks who has lived and breathed the subject all his life without even giving it much thought. Both types of expert have a lot to offer, but each only has half the story, and unfortunately I suspect they never really talk to each other and compare notes. In this Knotweed case I just wonder if there have been lots of people in white coats patting each other on the back having found a solution, while some old Asian guy on the other side of the world has some nugget of wisdom that the docs could have used, if only they'd asked him.

 

anybody use "Encarsia Formosa" for the control of whitefly - i assume that it is an introduced species.

 

I think that the difference is that Encarsia will not survive outside the closed greenhouse environment, and once the whitefly are below a certain level the Encarsia population collapses, hence the need for multiple introductions.

 

Blackthorn,

Its just an example of intoduced species but with global warming we might find them over-wintering. We all live with a vast number of introduced, deliberately or accidentially, species its just that some of these go wrong and its those that make the headlines. Grey squirrels, dormice spring to mind

My instinct is not to introduce a bug to help beat knotweed.

 

Likewise. Plenty of species have been known to adapt and evolve to different environments. Lesser of two evils - at least knotweed can be seen by the naked eye, rather than minute insects.