Nature’s answer to deadly tree pest is paying off in the uplands of Wales

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New natural methods of stopping Wales’s deadliest tree pest in its tracks are already beginning to pay off at field trials in the upland forests near Tregaron.

Hylobius abietis - the large pine weevil – is the single most important insect pest of plantation forestry in Europe and there are fears that climate change could increase populations.

But now researchers from the Aberystwyth-led IMPACT project have discovered that a cocktail of the pest’s natural enemies - microscopic nematode worms and fungi – are a potent weapon in fighting back against Hylobius.

“Hylobius can kill up to half the young trees after re-planting,” said Professor Hugh Evans, Head of Forest Research in Wales and co-ordinator of the project, which is part funded by the European Regional Development Fund (ERDF) through the Ireland Wales Programme (INTERREG 4A), with match funding from Forestry Commission Wales.

“Now latest results from trials at Cwm Berwyn suggest that a cocktail of entomopathogenic natural agents can be used to attack and kill the larvae, pupae and young adult Hylobius, reducing the pest population by at least 40 per cent.”

The IMPACT researchers have drafted in reinforcements for the microscopic nematode worms that are already part of the armoury for Forestry Commission Wales in its battle against the weevil.

“Building on the pioneering work of our project partners at Swansea University, led by Professor Tariq Butt, College of Science, we are testing insect-killing fungi alongside the nematodes, at reduced concentrations compared to using them separately,” said Professor Evans.

“Results are highly promising giving increased efficiency of natural control, further reducing the need for chemical protection of young trees.”

Forest Research in Wales is looking at improved pest control measures through IMPACT with partners from Swansea University and the National University of Ireland, Maynooth.

Top of the agenda for the Integrated Management of forest Pests Addressing Climate Trends (IMPACT) team is assessing just how changing climate will influence the damage caused by forest and woodland pests.

“As the climate becomes warmer and wetter, the conditions will improve for Hylobius, so it is important that we should have even more effective controls,” he said.

The IMPACT scientists expect future weather extremes – drought, flooding, higher and lower temperatures – to put woodlands under increasing levels of stress.

Increased stress lowers the defences of trees, opening them up to attack from insect pests such as the pine weevil,  bark beetles, wood boring beetles and a wide range of root and leaf feeders, all of which affect tree growth, sometimes leading to tree death.

The key will be biological control integrated into novel monitoring regimes, concentrating especially on microbial control agents – fungi, bacteria, viruses and parasitic nematodes.

The IMPACT partnership already has a strong track record in use of these agents and expects to deliver improved technology to any land users whose trees are at risk from pest infestations.

Contact: Professor Hugh Evans, Forestry Research in Wales: Tel – 0300 068 0079; Guy Pargeter, Taliesin Communications: Tel – 01970 832375.


IMPACT – Integrated Management of forest Pests Addressing Climate Trends

This is a new project which is part funded by the European Regional Development Fund (ERDF) through the Ireland - Wales Programme (INTERREG 4A) and part funded by Forestry Commission Wales. The project, called Integrated Management of forest Pests Addressing Climate Trends – IMPACT - is led by Forest Research in Wales, a research unit launched in 2009 based at Aberystwyth, with the National University of Ireland at Maynooth and Swansea University. It runs for three years to 31 December 2012.

Forest Research

Forest Research is the research agency of the Forestry Commission. It is a world leader in the research and development of sustainable forestry and is Britain's principal organisation for forestry and tree related research, with specialists covering topics from managing timber, and protecting woodland from climate change, to tracking new pests and diseases, and examining the social and community benefits of woodland in urban and rural areas.

Forest Research in Wales

The newly established Forest Research in Wales Unit based in Aberystwyth, look at research opportunities within Wales and elsewhere. Interactions with a wide range of stakeholders, particularly with Forestry Commission Wales and the Welsh Assembly Government, are being developed to scope and deliver research and appropriate technology transfer. Links with the research community in Wales, universities and government organisations are also being developed.

Swansea University

Swansea University is a world-class, research-led university situated in stunning parkland overlooking Swansea Bay on the edge of the Gower peninsula, the UK's first Area of Outstanding Natural Beauty. Founded in 1920, the University now offers around 500 undergraduate courses and 150 postgraduate courses to more than 13,800 students. Visit

NUIM, Maynooth

National University of Ireland, Maynooth is one of four constituent universities of the federal National University of Ireland. The university traces its origins directly to the foundation in 1795 of St Patrick’s College, Maynooth and it is Ireland's second oldest university.

Forestry Commission Wales

About 14% of Wales is covered by woodlands. Of this, 38% (126,000 hectares/311,000 acres) is owned by the Welsh Assembly Government. Forestry Commission Wales is the Welsh Assembly Government’s department of forestry and manages these woodlands on its behalf.
More information on the woodlands of Wales is available on