Summary
Integrated Management of Hylobius
The latest guidance on the integrated pest management of the insect Hylobius abietis is contained in this Forest Research Report. It incorporates all the most recent research findings on alternatives to the use of conventional pesticides for protecting trees from Hylobius damage. In addition, as a separate Appendix, it summarises knowledge and guidance on the safe use of the insecticide acetamiprid, which is increasingly being used as an alternative to cypermethrin.
This programme is investigating the potential of Integrated Forest Management (IFM) to minimise the current emphasis on insecticide applications to protect transplants from feeding damage by Hylobius abietis the principal forestry restocking pest. Our research evaluates alternatives to the traditional insecticide-based approach to plant protection and aims to investigate and combine other methods. This includes changes to forest management practices to reduce populations and damage by Hylobius; and to predict and rationalise the ‘risk’ to transplanted trees.
Research objectives
The programme aims to co-ordinate, promote and synthesise all aspects of research on the large pine weevil, Hylobius abietis. The approach focuses on quantification of the effects of factors known to reduce Hylobius populations and damage and combines them in a practical way to produce compound beneficial effects. IFM as a concept parallels the Integrated crop management (ICM) approach being increasingly adopted in agriculture and the approach uses conventional Integrated Pest Management (IPM) as the core tool augmented with silvicultural and management techniques to reduce Hylobius damage.
Status
The programme started in April 1999 and is ongoing.
Contacts
nrs_entomology@forestresearch.gov.uk & Dr Roger Moore
Funders and partners
This research is funded by the Forestry Commission Advice and scientific support for tree health programme.
Part-funding from EU Regional funds under the Interreg IIIA initiative between Wales and Ireland (Welsh European Funding Office).
Research and guidance on alternative methods of managing Hylobius abietis
The large pine weevil (Hylobius abietis) is the most serious pest of newly planted or naturally regenerating woodland trees on restocking sites in the UK and Ireland. On affected sites, in the absence of protective measures, losses of replanted trees will average around 50%, but in the worst cases all trees can be killed. The need to find alternatives to the use of synthetic pyrethroid insecticides led to a collaborative research effort across the UK forest industry which investigated over 100 different approaches on 22 different trials sites.
Several lower toxicity insecticides were identified that can effectively protect trees, as well as non-chemical approaches that may work when on-site populations are predicted to be lower.
Three scientific papers have been produced by Forest Research fully reporting on the results of these experiments, and they are freely available as follows:-
Two trade journal articles have also been produced that summarise these scientific papers:-
Willoughby, I.H. and Moore, R. (2021). Defending our trees. What’s the latest in the battle against Hylobius? Trees, summer 2021, 20-21. www.charteredforesters.org
Willoughby, I.H. and Moore, R. (2020). Hylobius attack: other ways of protection. Forestry and Timber News 102, 64-65. https://www.confor.org.uk/news/ftn-magazine/
Previous Projects
Project: CAN DO Novel Trapping Systems for Monitoring and Control of Hylobius abietis (2019-2023)
Project Partners: Forest Research, Natural Resources Institute at the University of Greenwich and Sentomol Pest Management Solutions.
Project objectives
To replace current billet traps with traps baited with a dispenser releasing a blend of synthetic pine compounds at a more consistent rate and for longer periods than natural billets.
To develop a lure and kill strategy to suppress weevil populations using biological control agents (BCAs) deployed within a modified trap.
Project outcomes
Two trap designs were developed, the Hylopod® M (manual) and the Hylopod® RS (remote sensing). The Hylopod M, trap and lure device, was designed to directly replace billets as a means of monitoring for Hylobius and provide data for the Hylobius Management Support System (HMSS). The Hylopod RS included a camera system to remove the need for manual inspection of trapping points in the future.
Traps proved to be durable, re-usable and an effective replacement for billets. They remained intact throughout multiple field trials carried out over three years with no losses.
Specific Hylobius lures were developed to work in conjunction with the Hylopod traps. The lures attracted significantly more weevils to traps in the field than were caught in unbaited traps. Traps baited with the lures caught more weevils than those baited with commercially available lures, and at least as many as those baited with pine twigs renewed each week. The number of weevils attracted to lure-baited traps in the field did not diminish by more than 50% over one month relative to catches with billets, improving the longevity of consistent captures over a longer time-period. Although the overall numbers of weevils captured in Hylopod traps were less than on billets, the ratio caught in traps versus billets in each area was consistent.
The efficacy of several biological control agents (BCA) against adult Hylobius was assessed in laboratory bioassays. The nematode Steinernema carpocapsae and the fungus Beauveria bassiana killed over 50% of weevils exposed to a high dosage. All other tested agents achieved comparably low mortality rates. Further work on S. carpocapsae demonstrated that infection with the nematodes kills a minimum of 50% of the weevils within a month.
For delivery of biological control agents, a cost efficient and biodegradable delivery device, the biological control agent delivery device (BCADD), was developed to administer entomopathogenic nematodes (EPN) in the field. Laboratory testing of the BCADD confirmed that within 24h of entering the device 50% of the weevils carry nematodes and that within 48 hours, 97% of weevils had vacated the device. On average insects left the device after 2 hours.
The finalised trap and lure caught low numbers (<1.5 per trap) of non-target invertebrates.
Contact nrs_entomology@forestresearch.gov.uk for more information.
Project: Biological Pest Control of Insect Pests that Threaten Tree Health (BIPESCO) (2014 – 2017)
Project Leads: Prof. Tariq M. Butt (Swansea University), Dr Glyn Jones (Fera) and Dr Roger Moore (Forest Research)
Additional project consortium members: industry partners representing the supply chain (Maelor Forest Nurseries Ltd, Lisk & Jones Consultants Ltd, Tilhill Ltd, Sentomol Ltd, MycoSolutions Ltd, Ecovid Ltd, Bord na Mona Ltd, Fargro Ltd).
Project objectives
Develop environmentally friendly “biopesticides” based on entomopathogenic fungi and botanical semiochemicals to control insect pests that are a major problem in forestry.
Evaluate different strategies which could enhance the efficacy of the control agents and optimize control.
The project focused on four pests: large pine weevil (Hylobius abietis), black vine weevil (Otiorhynchus sulcatus), pine processionary moth (Thaumetopoea pityocampa) and Asian longhorn beetle (Anoplophora glabripennis). For the purposes of this summary, only work on the large pine weevil will be detailed.
The project objectives were accomplished through seven work packages WP1-7.
WP 1. Evaluate the efficacy of selected strains of EPF against target pests
Two strains of Metarhizium brunneum ARSEF4556, V275 (=Met52, F52) were identified as highly pathogenic to Hylobius adults.
WP2. Assess a range of botanicals for their attractant, repellent and pesticidal properties
Several plant and fungal derived compounds were identified which influenced the behaviour of Hylobius (e.g. acting as attractants or repellents). These were evaluated using different dispenser technologies developed with industry partners.
WP3. Identify synergies between EPF and botanicals
Combinations of entomopathogenic fungi and attractant/repellent compounds were investigated in laboratory and field trials. Field trials found that Hylobius could be inoculated with M. brunneum conidia by luring them to the fungus using pine billets. New lightweight traps were developed which were effective in mass trapping and lure & kill studies.
WP4. Determine compatibility of products and strategies under field conditions
Hylobius mass trapping using pitfall traps and “lure, release and kill” surface traps were evaluated in forest sites in Scotland. The latter was suitable for delivery of M. brunneum to control Hylobius. Field trials using surface traps to capture and inoculate Hylobius with entomopathogenic fungi demonstrated: high weevil mortality (up to 70%) and dissemination of entomopathogenic fungi within the wider population.
WP5. Demonstrate the efficacy of the products and strategies to stakeholders
WP6. Conduct risk assessment of products and strategies against non-target insects
Risk assessment studies showed that entomopathogenic fungi posed little or no risk to terrestrial and aquatic non-target invertebrates. Where traps are deployed, the risk is low since the traps exclude most non-target invertebrates e.g. ground beetles.
WP7. Conduct cost-benefit analysis (CBA) of products and strategies
The BIPESCO strategies are at various stages of technical development. The products and strategies arising from the BIPESCO project are at different stages of Technology Readiness Level. Some products such as M. brunneum Met52 are already sold for black vine weevil control, but the opportunity exists to use the fungus to control the other target species. The analysis considered the strategies against: (1) the current baseline i.e. existing pest control options, (2) a future baseline with fewer chemical control options. The benefits of the strategies are: (1) reduced reliance on chemical control, (2) a reduction in negative external impacts of chemical usage, (3) in some cases a positive impact on yield.
Contact nrs_entomology@forestresearch.gov.uk for more information.
Hylobius Management Support System
The main objectives of the programme are to improve our understanding of the behaviour, population dynamics and migration of the weevil. Using the knowledge gained thus far a series of major field surveys were started in 2003 to develop a Hylobius Management Support System (MSS) to allow Forest Managers to make more informed decisions to improve restocking practices.
Please note the Hylobius MSS is currently unavailable online (April 2025). Updated information will appear here by the end of 2025.
Aims of the Hylobius MSS
- To help foresters plan future clearfell restocking strategies to minimise transplant damage by Hylobius
- To help avoid unnecessary insecticide use and initial restock failure
- To reduce top-up insecticide applications and beating up of destroyed transplants
- To help users meet operational goals for restocking and satisfy requirements of Forest Stewardship Council (FSC) and UK Woodland Assurance Standard (UKWAS)
- To reduce overall costs of restocking by helping managers make informed, site-specific decisions.
What is the Hylobius MSS?
- Until recently, the Hylobius MSS was provided to end users as user-friendly online software.
- The Hylobius MSS uses factors influencing Hylobius population size to predict damage to transplants on clearfell sites in advance of restocking.
- It is a decision support tool to allow foresters to investigate the best management strategies to reduce Hylobius damage, insecticide use and costs of restocking clearfells.
Products
Hylobius Management Support System
A decision support system to help foresters predict and reduce damage and costs due to large pine weevil, Hylobius abietis.
Publications
- FR_Integrated management of Hylobius abietis in UK forestry (PDF-3 MB)
This new Note provides the latest guidance on the integrated pest management of the insect Hylobius abietis. In doing so it draws on some of the key findings after 7 years of an ongoing programme of collaborative forest industry research on alternatives to the use of the insecticide cypermethrin for protecting trees from Hylobius damage. In addition, as a separate Appendix, it summarises knowledge and guidance on the safe use of the insecticide acetamiprid, which is increasingly being phased in across the UK forest industry as an alternative to cypermethrin. - Managing the Pine Weevil on Lowland Pine (PDF-1900 KB)
Forestry Commission Practice Note 14 - Resistance of young conifers to feeding damage by Pine Weevil (PDF-786 KB)
Forestry Commission Information Note 87 - The assessment of site characteristics as part of a management strategy to reduce damage by Hylobius (PDF-145 KB)
Forestry Commission Information Note 38 - Managing the threat to restocking posed by the large pine weevil, Hylobius abietis: the importance of time of felling of spruce stands (PDF-34 KB)
Forestry Commission Information Note 61 - Developments in the integrated management of pine weevil (PDF-371 KB)
Forest Research Annual Report 2003-2004