Climate and the risk of pests and disease

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• Climate and the risk of pests and disease
• Primary research activities in this area
• Participatory evaluations of risk for potato
  tuber moth and Andean potato weevil in relation
  to climate parameters in the Altiplano
• Evaluation of climate and the utility of crop
  diversification for disease management
• Integrated predictions of future risk for potato
  tuber moth and potato late blight based on
  climate change predictions

2

• Climate and the risk of pests and disease
• Primary research activities in this area
• Participatory evaluations of risk for potato
  tuber moth and Andean potato weevil in relation
  to climate parameters in the Altiplano
• Evaluation of climate and the utility of crop
  diversification for disease management
• Integrated predictions of future risk for potato
  tuber moth and potato late blight based on
  climate change predictions

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From the LTRA-4 participatory community
assessment Farmers in our study area of the
Bolivian altiplano perceive pest problems to be
increasing, along with increasing resistance to
pesticides They identified potato tuber moth and
Andean potato weevil as priority constraints to
production
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Objectives Estimate Andean potato weevil and
potato tuber moth risk in three communities in
each of Umala and Ancoraimes, Bolivia (expanding
to Puno, Peru) Link pest risk with climate and
socioeconomic factors
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Methods Measure pest populations in a study
field in each of three communities in each of two
regions across three years Use a windows
approach to evaluate time intervals that impact
pest population growth in the field Evaluate the
relationship between risk and climate variables
across years using the site-year combinations as
replicates
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Pitfall traps used for sampling Andean potato
weevil
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Pheromone traps used for sampling potato tuber
moth
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Example data set from one community Andean
potato weevil 2006-2007 in the community
Jatuquira Number of adults of two species with
maximum temperature and minimum temperature
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Andean potato weevil 2006-2007 in three
communities in Umala The average number of
adults retrieved from traps
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Climate and pest populations As we gather more
site-year observations and compare summary
statistics, we are populating this figure for
different combinations of climate
statistics Associated socioeconomic and
management data will provide context
Each point indicates the result from one
community in one season
Population for one season
Climate summary statistic for one season
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• Climate and the risk of pests and disease
• Primary research activities in this area
• Participatory evaluations of risk for potato
  tuber moth and Andean potato weevil in relation
  to climate parameters in the Altiplano
• Evaluation of climate and the utility of crop
  diversification for disease management
• Integrated predictions of future risk for potato
  tuber moth and potato late blight based on
  climate change predictions

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How does season length influence disease
risk? Analysis in collaboration with the
International Potato Center Garrett et al.,
in revision for Ecological Applications
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Use of potato cultivar mixtures can reduce the
risk of potato late blight
Time
Garrett and Mundt 2000
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What is the effect of season length on the
utility of potato mixtures to manage disease?
RMR lt1 indicates a benefit from mixtures
Increasing season length

Garrett et al., in revision
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• Climate and the risk of pests and disease
• Primary research activities in this area
• Participatory evaluations of risk for potato
  tuber moth and Andean potato weevil in relation
  to climate parameters in the Altiplano
• Evaluation of climate and the utility of crop
  diversification for disease management
• Integrated predictions of future risk for potato
  tuber moth and potato late blight based on
  climate change predictions

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We are using GIS to map risk predicted from
disease and pest risk forecasting models
Estimates of potato late blight risk in the
altiplano 1995-1998 No disease
predicted 2001-2004
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(No Transcript)
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Estimates of disease and pest risk in the
altiplano We are developing risk maps for late
blight under climate change scenarios based on
existing models of the relationship between
climate variables and epidemiology
There are also models of weather effects on
potato tuber moth that we will draw on for
modeling that system
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Sporleder et al. 2004 Potato tuber moth response
to temperature in controlled environment
experiments Development rates for larvae and
pupae
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Developing a conceptual framework for the impacts
of global change on cropping system
constraints... to guide strategies... An early
version of assessment of biological relationships
follows this might function as one component of
a more complete model even limited to biology,
there are interactions across all scales
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Garrett et al. 2006
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Garrett et al. 2006
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• Evaluation of thresholds, interactions, and
  positive feedback loops
• A small change in temperature or precipitation
  does not necessarily imply a small change in
  disease risk
• Examples from epidemics follow
• Also need to consider interactions between
  changes in disease and pest risk and human
  capabilities for management

Garrett 2008
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The local inoculum load builds during the period
of conducive weather
Because plant disease pressure often increases
following a compound interest model, increasing
the length of the growing season slightly can
have a very large impact on inoculum load
Percentage inoculum saturation
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An Allee effect may produce thresholds for
pathogen reproduction (Allee effect lower per
capita reproduction in small populations)
Allee thresholds may produce larger impacts from
climate shifts than would be anticipated with
partial knowledge
Per capita reproduction
Pathogen population size
Garrett and Bowden 2002
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Feedback loops for disease management

• Management based on controlling local inoculum
  production becomes less useful as regional
  inoculum loads rise
• Field sanitation
• Intercropping and mixtures
• Resistance based on lower inoculum production

Utility of local management
Regional inoculum load
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Responding to climate change

• We are developing an integrated framework for
  evaluating responses to climate change for any
  given disease or pest
• Characterization of resources and needs in areas
  such as the following, at all relevant scales
• -Plant genetic resources for resistance and
  issues for their deployment
• -Producer knowledge and resources, and training
  systems
• -Historic and predicted population
  characteristics for pathogens, vectors, and
  biocontrol agents
• -Historic and predicted climate characteristics
• -The nature of interactions between these areas
• Then Validating the conceptual model