The scientists say they have tested the beetle's feeding preferences on several "important" British food plants etc. and are satisfied that the insect will only go for the Knotweed.
However, they have not tested the insect's preferences on ALL British plants, so at best, they can only put this arguement forward as hypothesis based on incomplete data.
Even if these insects do prefer Knotweed, and manage to decimate it. (Presumably their numbers would have multiplied into the millions to achieve such a feat). What happens then?
Do all these insects conveniently die off? or do they turn their attention to whatever other British native plants take their fancy?
I remain entirely unconvinced of any merit in this proposal.
Regards
Mike.