The Commonwealth Agricultural Bureaux International is making a fresh attempt to sell the idea of biocontrols to the UK with plans for release of agents to tackle Japanese knotweed.
The spread of knotweed in the UK has been so rapid and controls so limited that CABI says it is time to reconsider "natural controls", widely disapproved of in the UK.
But it points out that the latest DEFRA estimate for elimination using traditional methods is £1.56bn and can add 10% to site development costs.
"In countries like the USA, Canada, Australia and New Zealand, research into natural control is the first port of call when a new pest species is identified as an apparently unmanageable problem," said CABI principal investigator Dick Shaw. "This has not previously been the case in the UK or the EU."
Backed by British Waterways, Cornwall County Council, DEFRA, the Environment Agency, Network Rail, South West Regional Development Agency and the Welsh Assembly Government, CABI has been working since 2000 to seek identification of insects and pathogens which stop knotweed spreading in its native environment.
It has tested 79 of those identified to determine host specificity. All but two were rejected as likely to attack other UK organisms after testing in CABI's quarantine facility. The two are a Mycosphaerella leafspot fungus and a sap-sucking psyllid Aphlara itadori.
The two are believed to offer no direct threat to UK species or crops but the fungus has a complicated life cycle and work on the psyllid is ahead.
Memories of Australia's infamous cane toad fiasco and other species introductions are still fresh, but the Wildlife Trusts say the spread of knotweed is having a serious impact on native wildlife and they welcome research into control measures.
"Introducing any non-native species carries risks and must be thoroughly researched and planned, even for positive measures like biological control," said Trusts land use planning manager Fiona Mahon.
"But we recognise that the damage being caused by this invasive plant is so serious that if methods of controlling this plant biologically exist, they should certainly be investigated further."
