Transcript Slide 1

Climate and the risk of pests and disease
Primary research activities in this area:
1. Participatory evaluations of risk for potato tuber moth
and Andean potato weevil in relation to climate
parameters in the Altiplano
2. Evaluation of climate and the utility of crop
diversification for disease management
3. Integrated predictions of future risk for potato tuber
moth and potato late blight based on climate change
predictions
Climate and the risk of pests and disease
Primary research activities in this area:
1. Participatory evaluations of risk for potato tuber moth
and Andean potato weevil in relation to climate
parameters in the Altiplano
2. Evaluation of climate and the utility of crop
diversification for disease management
3. Integrated predictions of future risk for potato tuber
moth and potato late blight based on climate change
predictions
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
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
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
Pitfall traps used for sampling Andean potato weevil
Pheromone traps used for sampling potato tuber moth
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
28
60
40
13
20
0
Temp. Máx. y
mín.
Nº de adultos
80
-2
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Semanas
Premnotrypes sp
Rigopsidius piercei
Tº máx
Tº mín
Andean potato weevil 2006-2007 in three communities
in Umala: The average number of adults retrieved from
traps
Promedio de adultos
1,7
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
0,53
0,29
0
0,02
Vinto Coopani
Jatuquira
Premnotrypes spp
0,01
San Jose de Llanga
Rhigopsidius piercei
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
Population for one season
Associated socioeconomic and management data will
provide context
Each point indicates
the result from one
community in one
season
Climate summary statistic for one season
Climate and the risk of pests and disease
Primary research activities in this area:
1. Participatory evaluations of risk for potato tuber moth
and Andean potato weevil in relation to climate
parameters in the Altiplano
2. Evaluation of climate and the utility of crop
diversification for disease management
3. Integrated predictions of future risk for potato tuber
moth and potato late blight based on climate change
predictions
Year-round host availability
How does season
length influence
disease risk?
Regional inoculum load
Analysis in
collaboration with the
International Potato
Center
Dry season
Short season of host availability
Host available
Garrett et al., in revision
for Ecological Applications
Time through year
Use of potato
cultivar mixtures
can reduce the risk
of potato late blight
Time
Garrett and Mundt 2000
What is the effect of season length on the utility of
potato mixtures to manage disease?
1.6
Cajamarca
El Niño
Huancayo
El Niño
1.4
Quito
1.2
1
Corvallis
RMR
RMR <1
indicates
a benefit
from
mixtures
Cajamarca
La Niña
0.8
Huancayo
La Niña
0.6
0.4
0.2
0
Garrett et al., in revision
Predicted
regionalseason
inoculumlength
load (increasing)
Increasing
Climate and the risk of pests and disease
Primary research activities in this area:
1. Participatory evaluations of risk for potato tuber moth
and Andean potato weevil in relation to climate
parameters in the Altiplano
2. Evaluation of climate and the utility of crop
diversification for disease management
3. Integrated predictions of future risk for potato tuber
moth and potato late blight based on climate change
predictions
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: …
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
Sporleder et al. 2004
Potato tuber moth
response to
temperature in
controlled
environment
experiments:
Development rates for
larvae and pupae
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
Garrett et al. 2006
Garrett et al. 2006
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
Percentage inoculum saturation
The local inoculum load builds during
the period of conducive weather
70
60
50
40
30
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
20
10
0
Month 1
Month 2
Month 3
Month 4
Month 5
Month 6
Month 7
An Allee effect may produce thresholds for pathogen reproduction
(Allee effect = lower per capita reproduction in small populations)
Per capita reproduction
120
100
80
60
40
20
Allee thresholds may produce
larger impacts from climate
shifts than would be anticipated
with partial knowledge
0
Pathogen population size
Garrett and Bowden 2002
Utility of local management
Feedback loops for disease
management
120
100
80
60
40
20
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
0
Regional inoculum load
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