REPHRAME approach

Summary and benefits

The approach adopted enables the consortium to address the key questions posed by the REPHRAME project and which are interpreted in relation to how they relate to pine wood nematodes (PWN)/vector/tree interactions as detailed in the figure below.

The interactions between <em>Bursaphelenchus xylophilus</em>, its vectors in the genus <em>Monochamus</em> and living or dead host trees, with the 6 key questions then arising from knowledge gaps identified as the proposed research programme science

The gaps in current knowledge are clearly understood and will form the basis of the research undertaken in the project, and will look into the relation of the saprophytic and pathogenic components of the nematode life cycle and, critically, to the interaction (or not) with the vector Monochamus spp.

The main benefits of the inter-related research will be that the infection, population build-up, distribution and spread of PWN in individual pine trees will be investigated, in particular in trees with long-term latent infections, and statistically reliable sampling strategies will be developed.

Assessing the intrinsic pathogenicity of different races or strains of B. xylophilus

An important consideration both in assessing impacts and in developing improved sampling regimes will be the question of intrinsic pathogenicity of different races or strains of B. xylophilus. Thus, a range of molecular techniques have been employed to assess the potential origin and amount of genetic variation in the Portuguese populations of PWN, some within the PHRAME programme and others arising from international research effort and collaboration. These techniques are being developed as components of rapid and specific diagnostic and identification tools for PWN to supplement traditional extraction and morphological examination of nematodes. 

Assessing the dispersal tendency and any flight distance variation of European Monochamus species

Analyses of the natural spread of PWN from trees with the emphasis on the potential for long-distance dispersal with European Monochamus species, is critical for developing management strategies such as precautionary clearcuts.  Detailed studies of the flight capabilities of Monochamus spp, especially M. alternatus in Japan and China, indicate that most flight is very local (up to 100 m), but that longer distance flight (various estimates between 1.8 and 3.3 km) can also take place. The balance between local and long-distance natural spread is therefore an area which requires urgent consideration and provision of definitive advice, taking account of variation in beetle age/physiology and its local surroundings.  The dispersal tendency and any flight distance variation in relation to forest structure and tree density is a particular item to be assessed and improved Vector traps for early detection will be employed for determining the dispersal potential.

Quantifying the risk of infested wood packaging material, wood chips and isolated bark

The magnitude of the risk of infested wood packaging material, wood chips and isolated bark as a pathway for spread of PWN to healthy forests will be quantified experimentally. The key element of this research requirement is the assessment of risks from non-vector transmission of PWN in wood-based pathways that do not have Monochamus spp. associated with them. Consequently, the risk profiles of the different pathways must be assessed in relation to whether non-vector transfer of PWN to host trees is possible and, if so, what is the significance of the risk.

Investigating the resistance in pine trees to support breeding and reforestation

This is essential. When pine wilt reaches epidemic proportions, as has been the case in Japan, the capacity to continue growing susceptible species of Pinus is lost. Indeed, in some areas of Japan the local species of pine have been entirely replaced by other conifer genera, such as Cryptomeria and Chamaecyparis. The alternative is therefore to assess those Pinus species that have been shown to be resistant to PWN or which have some tolerance to the nematode and then to evaluate them as potential replacements for known susceptible hosts.

Examining the potential environmental and economic damage that PNW might cause outside of Portugal

This will be undertaken by taking into account possible climate change and the entire sylvo-climatic diversity of Europe. The information on the biology and pathogenesis of PWN in relation to a range of conifer hosts following introduction of the nematode to the crowns of trees during maturation feeding by Monochamus spp. is critical and essential to understanding and predicting likelihood of wilt expression.

Validating the modelling by field experimentation

Field experimentation in Portugal will validate the modelling as well as any latent infections. The latency in expression of wilt in PWN infested countries outside Europe which have cool climatic conditions is a factor that requires further detailed study to both refine the process models and also to design survey regimes to take account of the phenomenon in both wilt and non-wilt zones. As the reasons for and scale of latency are not well understood therefore, both direct experimentation and observation combined with refinement of the process-based models are required to quantify the extent of latency and to design survey regimes accordingly.

Interacting with on-going EU-funded plant health projects

The project will interact intensively with ongoing EU-funded research projects on plant health (such as those addressing pest risk analysis, identification methods and the development of early PWN detection methods) and will utilise and expand the results as much as possible of previous projects (such as PHRAME).

Bringing the wide ranging PWN and Monochamus knowledge base together is important in ensuring that rapid and relevant progress is made in addressing the important requirements of the project. To this end, the gathering of this global knowledge is a fundamental building block underpinning the main composite output of REPHRAME, namely the PWN Tool Kit (PTK). This will:

  • Synthesise data, both from the wider international research and development community and the data produced de novo by the REPHRAME consortium
  • Provide an innovative and interactive portal for stakeholders to interrogate the evolving state-of-the-art from REPHRAME
  • Enable customised outputs to be produced, ranging from basic advice through to precise and statistically valid procedures for sampling and management of PWN and its vectors.