Will climate change result in more pest and disease problems for agriculture? - Ray Cannon (FERA)


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  • Very usefull lecture for remind us how Climate Change is really threatened us in the future
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  • Carulaspis juniperi (Bouché), the juniper scale, may reach population levels high enough to severely damage plants, Carulaspis spp. (C. carueli and C. juniperi) are also found in the UK, albeit infrequently. In the UK, both species are at the edge of their natural range, but are expected to occur more commonly in this country in the future due to climate change.
    The cottony cushion scale (Icerya purchasi) is a polyphagous pest of woody plants, including Camellia, Citrus, Ilex, Magnolia, Prunus and Pittosporum, appears to be naturally spreading northwards perhaps as a consequence of global warming. Considered to be of Australian origin, I. purchasi has spread throughout the tropics, subtropics and the Mediterranean, widespread in southern European countries. In recent years, it appears to be surviving in central London (Chelsea) and Paris (Jardin des Plantes), although it is unlikely to establish widely outside of the sheltered, warm microclimate of London (except possibly in the south-west).
  • The report, Water for Agriculture – Implications for Future Policy & Practice, makes it clear that higher temperatures and lower rainfall in summer are likely to reduce river flow and so reduce the amount of water available for agriculture.
  • Soybeans grown at elevated CO2 levels (550 ppm) attract many more adult Japanese beetles than plants grown at current CO2 levels
  • Thus, the outcome – in terms of pest pressure and yield effects – of such multi-factorial responses to climate change will be difficult, if not impossible to predict. Nevertheless, it is important to search for generalisations, in terms of, as there are too many potential individual insect and pathogen responses to climate change to cope with on a case-by-case basis. However, conclusions can vary. For example, the pest status of cereal aphids in Southern Britain was predicted to decline significantly by the end of this century (Newman, 2005), although other studies have suggested that in general, aphids will become more serious pests, as temperatures and CO2 levels increase (Zhou et al., 1995; Percy et al., 2002; Harrington et al., 2007; Sun et al., 2009).
  • Remote sensing data for vegetated areas between 40°N and 70°N in Eurasia showed a persistent increase in the length of the growing season (18 versus 12 days) for the period 1981 to 1999 (Zhou et al., 2001).
    Advances of spring bud burst and flowering dates of deciduous trees in temperate ecosystems are in parallel with the global warming (Badeck et al., 2004).
  • ‘first leaf onset’ for Europe: 2.2 days decade-1 earlier over 1955–2002 (Schwartz et al., 2006)
    average advance of ‘spring/summer’ events: 2.5 days decade-1over 1971-2000 (Menzel et al., 2006)
    advancement of different spring events, between 2.3 and 2.8 days per decade (Parmesan, 2007)
    average shift in spring phenology (e.g. breeding, flowering or flying) was 5.1 days (Root et al., 2003)
  • Reich, P. B. & Oleksyn, J. (2008). Climate warming will reduce growth and survival of Scots pine except in the far north. Ecology Letters 11, 588-597.
  • Crop yields may increase in some areas: 1) New crops (adapted to new conditions); 2) Expansion into new areas (northerly regions); 3) CO2 Fertilisation effect +  temperatures & precipitation
  • Adaptation measures are activities that enable ecosystems to adjust to climate change
  • Mitigation involves reducing the actual level of CO2 (and other greenhouse gases) or reducing the rate of increase in CO2 levels. There are two main strategies available to mitigate CO2 increases: reduce emissions (i.e. at the source) or increase the photosynthetic biomass (the sink) (Zomer et al., 2008). Options for reducing CO2 emissions include changes in agronomic practices, such as reducing tillage and crop burning (Ortiz et al., 2008). Increased yields via improvements in crops (intensification) also have the effect of mitigating greenhouse gas emissions (Burney et al., 2010).
    Reforestation is the restocking of existing forests and woodlands which have been depleted, with native tree stock Afforestation is the process of establishing a forest on land that is not a forest, or has not been a forest for a long time by planting trees or their seeds.
    Methane emissions will lessen the greenhouse benefit of a tree grown in a reforestation programme
  • The main components of agricultural emissions are nitrous oxide (N2O) released from soils; and methane (CH4) from livestock.
  • Reforestation is the restocking of existing forests and woodlands which have been depleted, with native tree stock Afforestation is the process of establishing a forest on land that is not a forest, or has not been a forest for a long time by planting trees or their seeds. Methane emissions will lessen the greenhouse benefit of a tree grown in a reforestation programme.
    Increased yields via improvements in crops (intensification) also have the effect of mitigating greenhouse gas emissions (Burney et al., 2010).
  • Horse chestnut leafminer, Cameraria ohridella (cont.)
    In the UK, C. ohridella may prove to be of greater consequence to the health of Aesculus hippocastanum (and also Acer platanoides and A. pseudoplatanus, the other known hosts of C. ohridella) than other (native) leaf miners due to a combination of the following factors:
    • Multiple, overlapping generations can result in rapid infestation of leaves and both the primary and the second flush may fall prematurely; • Pupae appear to be extremely frost tolerant. This can lead to increasing populations from year to year even when winters are severe; • Numbers can build up rapidly following establishment in a new location, e.g. the heavy damage in Brussels during 2000, even though the moth was not noted in the previous year.
    • Rapid long distance dispersal arising from passive transportation on vehicles can lead to new infestations at locations remote from known centres of attack; • The pest does extremely well in hot dry conditions when the tree may be already suffering drought stress. C. ohridella can, therefore, be a contributory factor in further tree decline; • Spread via vehicles tends to favour establishment in urban areas where growing conditions are less than ideal and trees are less able to withstand the effects of additional stresses • Horse chestnut and the other known hosts are significant amenity trees in urban and suburban areas so that both visual damage and loss of growth are more serious than in rural locations. Trees heavily attacked by C. ohridella are not reported to die, but reduced growth of young trees has been noted. Continuing repeated defoliation,especially when it occurs early in the growing season, may lead to an overall gradual decline in tree vigour. The long-term effects are not yet known. Quarantine measures: It is not practical to prevent spread using phytosanitary measures because of the known propensity for passive dispersal of infested leaves on vehicles. Transportation to Britain is therefore highly likely and it is important to be aware of the possible establishment of the moth. Conclusions: It is unlikely that C. ohridella would be able to complete more than one or two generations even in a warm dry summer in the UK. However if this pest shows more climatic tolerance than observed to date, particularly combined with any increase in the frequency of hot dry summers, it may pose a greater threat than predicted on the basis of current knowledge. http://www.forestresearch.gov.uk/pdf/frpestanddiseases0001.pdf/$FILE/frpestanddiseases0001.pdf
  • The greatest economic losses from CLB in Asia have occurred in fruit-tree plantations, especially citrus
  • Climex prediction – any increase in mean temperatures will increase the potential for establishment and decrease the time required to complete a life cycle in the UK
  • It is a highly polyphagous herbivore, able to feed on plants from over 30 families, both monocots and dicots. It has a preference for legumes, preferring to feed on plants that are fruiting or forming pods
  • The northward expansion of the univoltine ecotype has already proved in Germany (Gathmann and Rothmeier 2005; Schmitz et al. 2002), and the same direction
    of expansion of the third, multivoltine ecotype of the ECB is taking place in recent decades.
    Sudden increase in the maize infestation over the territory of the Czech Republic during the unusually warm period of 1991–2000.
  • Diabrotica virgifera virgifera
  • Spread of the western corn rootworm in Europe, following an initial introduction into the former Yugoslavia, near Belgrade, c. 1992 (or before).
  • A severe infestation of white peach scales (WPS), Pseudaulacaspis pentagona has been detected on ornamental Indian bean trees, Catalpa bignonioides, in a private garden in Kent in 2006. There were ten trees which were imported from Italy approximately 4-5 years previously.
  • Evans et al. (2008). J. R. Soc. Interface (2008) 5, 525–531. (blackleg), caused by Leptosphaeria maculans,
    There was a large effect of predicted climate change on the start of phoma stem canker in spring, with predicted dates often 80 days earlier than during 1960–1990 (figure 2). The range of the damaging stem canker phase of epidemics was predicted to extend northwards from England into oilseed rape growing areas in eastern Scotland (white area in figure 2, currently unaffected by phoma stem canker). Furthermore, the predicted severities of phoma stem canker at harvest for 2020 and 2050 were much greater than during 1960–1990; the UK maximum mean severity increased from 1.7 (1960–1990) to 2.0 (2020) and 2.3 (2050) on the 0–4 scale for a harvest date of 15 July
  • R H A Baker, A MacLeod, R J C Cannon, C H Jarvis, K F A Walters, E M Barrow & M Hulme (1998) Predicting the impacts of a non-indigenous pest on the UK potato crop under global climate change: reviewing the evidence for the Colorado beetle, Leptinotarsa decemlineata. Brighton Crop Protection Conference - Pests and Diseases, Vol. III, 979-984. BCPC, Surrey, UK.
  • In terms of crops yields, the consequences of elevated CO2 are now well documented. In general, elevated CO2 stimulates the growth and yield of most, if not all the crops (except C4 crops such as sorghum), as long as soil moisture and water are not limiting (Kimball et al., 2002b). C3 and C4 plants respond differently to both temperature and atmospheric CO2 (Ehleringer & Monson, 1993; Ehleringer et al., 1997; Wand et al., 1999) and some C3 plants, such as cotton, appear to be particularly responsive to increased CO2 (Gao et al., 2008). The explanation for this difference was discovered recently and it concerns differences in nitrate (NO3–) assimilation between C3 and C4 species (Bloom, 2006). In a range of FACE experiments, elevated CO2 substantially increased photosynthesis, biomass, and yield in C3, but had little effect on C4 species (Kimball et al., 2002a).
  • Will climate change result in more pest and disease problems for agriculture? - Ray Cannon (FERA)

    1. 1. Will climate change result in more pest and disease problems for agriculture? Ray Cannon Fera Sand Hutton York,UK
    2. 2. INTRODUCTION • Main ‘drivers’ of a changing climate • Direct and indirect effects • Effects of CO2 on crops and pests
    3. 3. Main ‘drivers’ of a changing climate • An increase in atmospheric CO2 (and other greenhouse gases) • Producing increased temperatures (T°C) • Coupled with altered precipitation () Producing biological effects such as: • Phenological changes (early flowering) • Geographical range shifts • Man’s responses: crop and land-use changes
    4. 4. Direct effects of climate change • Longer (i.e. extended) growing seasons and frost- free periods • Warmer, milder winters • Increase in the frequency & intensity of precipitation, including: – Increase in ‘agriculturally significant’ extreme events (e.g. floods; storms). – wetter autumn/winter period – lower rainfall in summer – Shifting regional rainfall (wetter in NW; drier in SE) • Increased summer temperatures (Hotter & Drier)
    5. 5. Indirect effects of climate change • Reduced water availability – Summer droughts: reduced water supplies for agriculture and horticulture • Increased runoff, flash floods (extreme events) – Disease management problems? • Effects of increased CO2 – Changes in biomass & biochemistry of plants – Yield gains (C3 crops) and losses • Changes in type and variety of crops grown in UK
    6. 6. CO2 levels – CO2 varied between 180 to 300 ppm for 400,000 years – In phase with ice ages – Preindustrial levels were about 280 ppm – Current level is 385 ppm and rising by about 2 ppm per year – May reach 570 ppm by 2050? • A doubling of CO2 probably results in a temperature increase of ~3°C
    7. 7. Responses to elevated CO2 High Uncertainty The CO2 ‘fertilisation effect’: crops grown under elevated CO2 exhibit enhanced growth and yields – C3 plants (crops, grasses, trees, shrubs) are particularly responsive – C4 crops (maize, sugarcane, sorghum) are less sensitive – Changes occur: in chemical composition (C:N ratios), plant defences, biomass, leaf area, canopy structure, abundance and distribution – Big increase in fixation of C into organic matter (I.e. plant growth) but will it be sustained?
    8. 8. Plant defenses decrease (↓) as CO2 levels increase Soybeans grown at elevated CO2 levels attract more pests - than plants grown at current CO2 levels Experiments at high CO2 levels Photo by E Deluccia
    9. 9. Free-Air CO2 Enrichment experiments - enrich the atmosphere around part of a terrestrial ecosystem with controlled amounts of CO2
    10. 10. Pest and disease responses • Given a choice, many insect species prefer feeding on foliage grown under elevated CO2   sugar levels but nitrogen (14%) and lack of chemical defences • Insects lived longer and laid more eggs, but • Large-scale, Free Air CO2 enrichment (FACE) studies indicate decline in herbivory! • CO2-temperature interactions and trophic level effects make predictions difficult!
    11. 11. Changes in precipitation • Flooded soil – harvesting problems • Heavy rain – damage and bacterial infections (rots) • Warm and wet winters – fungal infections • Long dry periods in – Spring – can result in crop failure – Summer – growth and yield reductions
    12. 12. Reponses to temperature •Increases in: o insect pest burden oimpacts on vegetation may oBackground levels of feeding may oNumber of pest outbreaks may oInsecticide usage may have to increase Aphids may become more serious pests
    13. 13. Phenological changes (1) • Vegetated areas in Europe already show increase in the length of the growing season – Most plants (including crops) are flowering earlier • Spring bud burst & flowering dates of temperate deciduous trees are in parallel with global warming – Many insects are flying both earlier and later in the season, but – Dates of bud burst may not shift as much as insect emergence - asynchrony
    14. 14. Phenological changes (2) • Range of studies confirm change in timing of events • ‘First leaf onset’: 2.2 days decade-1 earlier (1955–2002 ) • Spring/summer events: 2.5 days decade-1 earlier (1971-2000) • ‘Spring events’: 2.3-2.8 days earlier per decade • Spring phenology (e.g. breeding, flowering or flying) was 5.1 days earlier • Butterflies: emerge much earlier and in advance of first flowering dates (=asynchrony)
    15. 15. Range shifts Tree species are expected to shift northwards as a result of climate change Trees responded relatively rapidly to climate warming in the past Climate warming will reduce growth and survival of some species, e.g. Scots pines
    16. 16. Crop and land-uses • Effects of climate change will vary with crop type and region • Crop yields may increase in some areas depending on availability of irrigation water & nitrogen • But there may be effects on nutritional value – e.g. Lower protein content • Unknowns include – extreme events; – pests & diseases
    17. 17. More on yields • Elevated CO2 enhances crop yields of C3 crops (stimulates photosynthesis) but may be limited by Nitrogen availability • C4 crops (maize, sorghum, millet) only benefit during drought stress – By 2020 global demand for maize projected to exceed that for wheat and rice – MAIZE: the world’s most important crop?
    18. 18. Adaptation measures • Farmers can decrease their vulnerability to climate change by: – Shifting planting dates – Growing alternative crops – Planting drought and heat-resistant varieties – Selecting crops which respond well to elevated temperatures and CO2 Adaptation measures are activities that enable ecosystems to adjust to climate change
    19. 19. Mitigation measures Reduce level of CO2 or rate of increase by: • reducing emissions (at the ‘source’) • increasing photosynthetic biomass (the ‘sink’) i.e. Produce less GHGs and/or capture more
    20. 20. Mitigation measures (1) • Reducing Green house gas (GHG) emissions from farming* (‘source’) • E.g. Reduced or less intensive tillage • Reduced fallow periods in summer • Reduced crop burning (non-UK) • Precision farming • Incorporating crop residues • Rotations of forage crops N.B. Agricultural production accounts for 10-12% of all Man’s GHG emissions
    21. 21. Mitigation measures (2) • Increasing photosynthetic biomass (‘sink’) – afforestation and reforestation – new large-scale plantations – rehabilitation of degraded land – more trees in agricultural areas – Increased yields via improvements in crops “a resilient food system is one which can withstand, or recover quickly from, sudden shocks”
    22. 22. Factors driving the spread of pests New species are arriving as a result of both Man’s influence and climate change: • Natural expansion into unfilled ranges • Climate change driven shifts in ranges • Active dissemination on vehicles • Passive transport on traded plants and plant products • Active flight (migrant species)
    23. 23. Cameraria ohridella Natural spread and passive transport Horse chestnut leaf miner
    24. 24. Horse chestnut leaf miner Cameraria ohridella First seen in northern Greece in the late 1970's Appeared in Austria in 1989 and has since spread throughout central and eastern Europe. Arrived in the UK in 2002 and has rapidly spread northwards
    25. 25. Plant health pests • Scale insects • Western corn rootworm • Citrus longhorn beetle • European corn borer • Southern Green Shield Bug • Colorado beetle • Old World bollworm • Phoma stem canker
    26. 26. Citrus longhorn beetle – Anoplophora chinensis
    27. 27. Damage caused by A. chinensis
    28. 28. Difficult to detect! Adult Citrus longhorn beetle on a feeding tunnel in a thin stemmed host (Acer) with exit hole
    30. 30. Any increase in average temperatures will increase the potential for establishment and decrease the time required to complete it’s life cycle in the UK
    31. 31. Southern green shield bug Nezara viridula • Highly polyphagous • >100 crops • serious pest of food and fibre crops • legumes, such as beans and soybeans • Spreading northwards • 2003, three breeding colonies in SE England
    32. 32. European corn borer (1) •Pest of maize •Northward expansion in Europe •One or two generations •Possible occurrence of 2nd generation in areas where there is presently only one •Increased pest pressure Ostrinia nubilalis
    33. 33. European corn borer (2) • Gradually extending its range northward through Europe • Regular migrant to UK • Breeding colonies mugwort • 2010: damage seen for first time in maize crops in south-west England
    34. 34. Western corn rootworm – a maize pest
    35. 35. Western corn rootworm - UK is at the edge of its range, - Could complete life cycle in most years. - Considerable annual variation. - By 2050 the average will be like a very hot year (1995). Climate Change (2050) Degree days available for development in different years Cool (1996) Hot (1995)
    36. 36. White peach scale Pseudaulacaspis pentagona •Pest of deciduous fruit and nut trees (peach, walnut) and vines •Infestations cause dieback of twigs and branches and eventually death of the trees •Established outdoors for the 1st time in 2006, in Kent
    37. 37. Plant pathogens & Diseases – blackleg* • Increased soil moisture, changes in the pattern of precipitation, elevated night-time temperatures and milder winters could all favour plant pathogens – increase the range and severity of phoma stem canker winter oilseed rape predicted (Evans, 2008) “The effects of climate change may be on the pathogen, the host or the host–pathogen interaction” *Leptosphaeria maculans
    38. 38. Colorado Beetle Life Cycle
    39. 39. Leptinotarsa decemlineata ecoclimatic indices predicted by CLIMEX for 1961-1990
    40. 40. Leptinotarsa decemlineata ecoclimatic indices (EI) predicted for 2050 by CLIMEX under the HadCM2 climate change scenario.
    41. 41. Effect of Climate Change for the Colorado Beetle • Potential range expansion of 120% – 79 additional 0.5º latitude/longitude grid cells climatically suitable for colonisation • Average northerly increase of 3.5° latitude (= 400 km) • In total, 99.4% of the area of potato production in GB would be vulnerable
    42. 42. Climate change and weeds – upsetting the balance with crops • Any direct or indirect effect of climate change that differentially effects the growth and fitness of weeds, relative to crops, will alter weed-crop interactions – sometimes to the detriment of the crop, sometimes to it benefit* – Many of the ‘worst’ weeds are C4 plants (which may benefit from temperature and low dryness) – Most crops are C3 plants (which may benefit from in CO2) *D T Patterson (1995) Weeds in a Changing Climate
    43. 43. Implications of climate change for pest, weed and disease management • More pests and diseases but possibly off-set by increased yields? • New crops with new niches for invasive pests and diseases • Increased pesticide use and possible loss of function?
    44. 44. END OF TALK
    45. 45. Robust and resilient farming systems (What & How?) • “Integrated, biologically balanced crop management systems” • “enhance the inherent adaptability of the system” • “maintain resilience and buffer climate change” • What can we do to build resilience? • Discuss!
    46. 46. Opportunities and risks based on Defra’s Climate Change Plan* • Hotter, drier summers and warmer, wetter winters – Opportunity to grow new crops (e.g. olives and apricots) or existing crops further north (e.g. vines) – Some increased yields and less frost; • BUT – Increased losses to pests and diseases – reduced quality and yield of some current crops. http://www.defra.gov.uk/environment/climate/documents/climate-change-plan- 2010.pdf
    47. 47. Opportunities and risks from climate change (2) • Drought – Loss of pastures – Lack of water – Reduced crop yields • Increased incidence of extreme weather events – Increased soil erosion – Storm and flood damage.
    48. 48. Adaptation solutions • Improved pest management strategies – To cope with increased climatic variability • Changes in agronomic practices – Earlier planting dates – New, improved varieties and cultivars