Epidemiological modelling of Phytophthora ramorum, sudden oak death, West Coast of the USA, England and Wales, plant pathology, landscape pathology. Connectivity loss in the North American power grid due to the removal of transmission substations.

1. Epidemiological modeling of
Phytophthora ramorum: network
properties of susceptible plant genera
movements in the UK nursery sector
Marco Pautasso,1 Tom Harwood,2 Mike Shaw,2
Xiangming Xu3 & Mike Jeger1
1 Imperial College London, UK
2 University of Reading, UK
3 East Malling Research, UK
SOD Symposium III,
8 Mar 2007

2. Disease spread in
a globalized world
number of passengers per day
From: Hufnagel, Brockmann & Geisel (2004) Forecast and control
of epidemics in a globalized world. PNAS 101: 15124-15129

3. Epidemiology is just one of the
many applications of network theory
Network pictures from:
Newman (2003) NATURAL
The structure and function
of complex networks. food webs
SIAM Review 45: 167-256
cell
metabolism
neural Food web of Little Rock
networks Lake, Wisconsin, US
ant nests sexual
partnerships
DISEASE
SPREAD
family
innovation networks
Internet flows co-authorship HIV
structure railway urban road nets spread
electrical networks networks network
power grids telephone calls
WWW
computing airport Internet E-mail
committees
grids networks software maps patterns
TECHNOLOGICAL SOCIAL
Modified from: Jeger MJ, Pautasso M, Holdenrieder O & Shaw MW (2007) Modelling disease
spread and control in networks: implications for plant sciences. New Phytologist in press

4. Different types of networks
local small-world
random scale-free
Modified from: Keeling & Eames (2005) Networks and epidemic models. Interface 2: 295-307

5. Epidemic development in different types of networks
scale-free
random
2-D lattice rewired
2-D lattice
1-D lattice rewired
1-D lattice
N of nodes of networks = 500;
p of infection = 0.1;
latent period = 2 time steps;
infectious period = 10 time steps
From: Shirley & Rushton (2005) The impacts of network topology on disease spread.
Ecological Complexity 2: 287-299

6. Temporal development; England & Wales, 2003-2005; n = 1104
100
Records positive to P. ramorum
75 nurseries/
n of records
garden
centres
50
25
0
3
4
5
03
3
04
4
05
5
3
4
5
-0
-0
-0
l-0
l-0
l-0
-0
-0
-0
n-
n-
n-
pr
pr
pr
ct
ct
ct
Ju
Ju
Ju
Ja
Ja
Ja
O
O
O
A
A
A
Data source: Department for Environment, Food and Rural Affairs, UK

7. Temporal development; England & Wales, 2003-2005; n = 1456
250
Records positive to P. ramorum
200
estates/
n of records
environment
150
100
50
0
3
4
5
03
04
05
4
5
3
3
4
5
-0
-0
-0
l -0
l -0
l-0
-0
-0
-0
n-
n-
n-
pr
pr
pr
ct
ct
ct
Ju
Ju
Ju
Ja
Ja
Ja
O
O
O
A
A
A
Data source: Department for Environment, Food and Rural Affairs, UK

8. Temporal development; England & Wales, 2003-2005; n = 704
Nursery records positive to P. ramorum
100%
UK origin
75% non-UK origin
n of records
50%
25%
0%
3
4
5
3
4
5
3
4
5
03
04
05
-0
-0
-0
l-0
l-0
l-0
-0
-0
-0
n-
n-
n-
pr
pr
pr
ct
ct
ct
Ju
Ju
Ju
Ja
Ja
Ja
O
O
O
A
A
A
Data source: Department for Environment, Food and Rural Affairs, UK

9. England and Wales: records positive
to Phytophthora ramorum
n = 2788
Jan 2003-Dec 2005
Courtesy of
Richard Baker, Data source: DEFRA, UK
CSL, UK

10. Web of susceptible genera connected by Phytophthora ramorum (based on
genus co-existence in 2788 positive findings in England & Wales, 2003-2005)
Viburnum
Camellia Umbellularia
Castanea Taxus
Syringa
Drimys
Fagus Rhodo-
dendron
Festuca
Hamamelis Quercus
Kalmia Pieris
Laurus Magnolia Parrotia
Leucothoe
Data source: DEFRA, UK

11. Frequency distribution of number of plant genera affected by
Phytophthora ramorum by n of records in the database of 2788
positive findings in England & Wales, 2003-2005)
1.2
log10 number of affected genera
y = -0.33x + 1.27
1.0 2
R = 0.93
0.8
0.6
0.4
0.2
0.0
0.0 1.0 2.0 3.0 4.0
log10 n of positive P. ramorum records in database
Data source: DEFRA, UK

12. Connectivity loss in the North American power grid
due to the removal of transmission substations
transmission nodes removed (%)
From: Albert, Albert & Nakarado (2004) Structural vulnerability of the
North American power grid. Physical Review E 69, 025103

13. Acknowledgements
Alan Inman, Department for Environment, Food
and Rural Affairs, UK
Claire Sansford, Judith Turner
& Richard Baker,
Central Science Laboratory, York, UK
Sandra Denman & Joan Webber,
Forest Research, Alice Holt, UK
Ottmar Holdenrieder, ETH, Zurich, CH
Jennifer Parke, Oregon State University

14. References
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