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07/06/2014

The scientific challenges . Dr. James Pendlebury Chief Executive, Forest Research. 1. 07/06/2014. A newly arrived organism …. Fitness traits. Selection components. !. ?. !. POW. WHAM. ZAP. !. Mutation. Genetic bottleneck. 2ry introductions. Sex. Introgression. Hybridisation.

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07/06/2014

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  1. The scientific challenges Dr. James Pendlebury Chief Executive, Forest Research 1 07/06/2014

  2. A newly arrived organism … Fitness traits Selection components ! ? ! POW WHAM ZAP ! Mutation Genetic bottleneck 2ry introductions Sex Introgression Hybridisation After Brasier, 1987

  3. Pathogen identity and biology Sporulation Infection Petiole Ascomycete Two parts to the life cycle that look different: General model Anamorph Conidia Sex Vegetative clonal Pathogen grows and causes disease Teleomorph Apothecia Ascogonia Ascospores Recombination Variability Infects new leaves

  4. Impact of invasives in natural environment vs agricultural systems How long is this phase? E Im Impact A Im 0 10 18 20 25 30 Years Waage et al. 2005

  5. Scientific Issues – Insect Pests • Taxonomy & diagnosis • a major issue in tree pathology, but less of a problem for • insect pests (larger size; relatively easy to recognise)

  6. Behaviour of insect populations Spread & dispersal • spread of many pathogens (small particles) can be • described by simple dispersion models, but spread & • dispersal of insect pests is more difficult to model because • of active movement & complex behaviours. • dispersal distances are related to size: • Chalara (small spores): 10-40 km/year • Emerald ash borer: 5- 40 km /year • Pine tree lappet moth: 2-5 km/year • Asian longhorn beetle: <100 m /year

  7. Spread & dispersal • it gets complicated when an insect is the vector or • potential vector of a pathogen • - acute oak decline (Agrilus beetle vector?) • - pine wood nematode (longhorn beetle vector) • human-assisted transport and trade greatly increase the • number of pathways along which pathogens and insect • pests can travel, and adds to unpredictability

  8. Behaviour of insect populations Year-to-year dynamics Annual variation in insect populations and rates of increase are not well understood and therefore, frequency, duration and intensity of outbreaks are difficult to predict. Climate is a key factor. It sets limits to insect distributions and underlies the response to climate change, hence research on: • climate matching studies (CLIMEX modelling) • for invasive species (e.g. PtLM, OPM) • changes in the distribution and impact of bark • beetles and large pine weevil (Hylobius) • future outbreaks of spruce aphid (Elatobium)

  9. Impact When is an outbreak an outbreak? It depends on whether we consider there is a problem, i.e. whether there is a significant impact. • social, environmental & economic • impacts • Economic impact assessment - is the • cost of control justified compared with • the potential reduction in impact? • economic costs are obvious when • trees are killed • but are very difficult to estimate when • effects are sub-lethal (growth loss) or • non-timber values are considered

  10. Control & management Short-term – eradication of invasive species, depends crucially on rapid action as soon as the pest is discovered • detection & monitoring systems • contingency plans • coordinated response ALB outbreak at Paddock Wood, 2012

  11. Control & management Long-term – management of established and native insect pests, is constantly having to adapt and change: • pesticide landscape is always changing • - EU pesticide reviews • - trials of alternative insecticides for Hylobius • reducing pesticide use / non-chemical options • - alternative silvicultural systems • - biological controls • new issues • - new outbreaks because of climate change • - new problems on novel tree species & new • genotypes

  12. Species - Principal conifers Mid-20th century Sitka spruce Norway spruce Scots pine Corsican pine Lodgepole pine European larch Japanese larch Hybrid larch Douglas fir Now Sitka spruce Norway spruce Scots pine Corsican pine Lodgepole pine European larch Japanese larch Hybrid larch Douglas fir

  13. Species - Principal broadleaves Mid-20th century Oak Beech Ash Elm Birch Sweet chestnut Hazel Hawthorn Alder Willow Now Oak Beech Ash Elm Birch Sweet chestnut Hazel Hawthorn Alder Willow

  14. Dothistroma needle blight Potential alternatives to Corsican pine: • Pre-DNB • Pinus nigra ssp. laricio • Pinus sylvestris • P. radiata • P. ponderosa • P. muricata Contingency species • Post-DNB • Pinus nigra ssp. laricio • Pinus sylvestris • P. radiata • P. ponderosa • P. muricata Pinus ?

  15. Species diversification Picea orientalis Oriental spruce Pinus pinaster Maritime pine Cedrus atlantica Atlantic cedar Pinus peuce Macedonian pine Sequoia sempervirens Coast redwood Cryptomeria japonica Japanese red cedar

  16. Veteran trees

  17. Importance of genetic diversity in resilience A sustainable long-term strategy for tree health depends on high genetic diversity Resilient populations enable evolutionary processes to take place How to retain resilience under times of change? Ensure regular cycles of regeneration

  18. Diversity = Resilience A constant supply of seedlings leads to plenty of raw material for natural selection The population gradually adapts to the new pest or disease by increasing the frequency of the most resistant genotypes. This assumes the whole population will not be wiped out before genetic adaptation can occur. Manage for multi-aged, multi-species forests For plantations, grow well adapted i.e. locally sourced material. Risk of ‘future’ climate matching is that trees are ill-adapted to the current climate Particularly susceptible to pests and diseases Under stress during their early life stages when most vulnerable.

  19. Resistant genotypes? Leave it to Nature Influx of disease A Influx of disease B No idea which pest or disease is going to strike next. The only way to achieve resilience is to have broad intra-specific genetic diversity. Those that are not-resistant will be lost and the frequency of resistant genotypes will increase with time under natural selection. Resistant to disease A Resistant to disease B

  20. Fears of durable resistance If disease controlled by just 1 or few ‘major’ genes, resistance soon overcome Poplar and Wheat - Big problems in past Better if a few ‘minor’ genes each make a small contribution to resistance Breeding is then a moving front in parallel with the evolving pest ‘Durable’ resistance Resistance breeding never stops!

  21. Contributions from Social Science Addressing tree pest concerns through: Recognising and understanding complexity e.g. human behaviour, supply chains Challenging traditional frameworks that influence responses to tree pests e.g. assumed significance of impacts Disentangling stakeholder roles and responsibilities Re-designing public outreach and risk communication – Citizen science Communicating social science outputs 21 07/06/2014

  22. Forest Research Thank you to the following colleagues who contributed slides or ideas to this talk: Dr. Joan Webber, Professor Clive Brasier, Dr. Anna Brown, Dr. Gary Kerr, Dr. Richard Jinks, Dr. Sandra Denman, Dr. Steven Hendry, Dr. Mariella Marzano, Dr. Norman Dandy, Dr. Joan Cottrell, Dr. Steve Lee and Dr. Nigel Straw Acknowledgements

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