1. Nik Cunniffe 20 th September 2012 1

2.  Some examples of previous models ◦ Individual based model for citrus canker ◦ Metapopulation model for Phytophthora ramorum  Compartmental model of Dutch Elm disease  Modelling when data is limited  What do I want you to tell me?

3. - Canker detected in 1995 - Threat to $9 billion industry - Statewide eradication program -125ft then 1900ft control radius -12 million trees removed (total cost ~$1 billion) - Abandoned in 2006

5. Optimum cull radius Note “optimum” has an associated risk if even slightly wrong... Cunniffe, N.J., Stutt, R.O.J.H, DeSimone, R.E., Gottwald, T.R. and Gilligan, C.A. (in preparation for PLOS Computational Biology)

6. - Exotic invasive pathogen in NW Europe, UK & USA - Generalist; infects many forest species (not just oaks) - Epidemic particularly well established in California - Already killed huge number of trees in California - Spreading in UK (mainly driven by larch) Oak Bay laurel Large scale mortality

9.  Current idea is to use the metapopulation model  Tracks disease status of individual trees  Projected to a small-scale grid (25m x 25m)  No explicit model of vector density (assume highly correlated with number of infectious trees)  Stage one of the current proposal does not include ◦ Environmental drivers ◦ Host demography ◦ Extensive parameterisation

10. An important decision is compartmental structure S = healthy trees E = latently infected trees (cannot spread ~ 6 weeks) C = infected live trees: can spread but “invisible” D = dead trees: more infectious, but “easy” to find R = removed trees (cut down or died too long ago)

11. Thanks to Anthony and his team

12.  Dispersal of Scolytus spp. beetle vectors?  Time variation in vector density?  Historic spread for model parameterisation?  Rate of primary infection (i.e. influx)?  Current extent and location of infection?  Effect and extent of previous controls?

13.  Adapt parameters from previous studies where possible  Sensitivity analyses to unknown parameters (e.g. infection rate)  Hope pattern is robust  Can offer no guarantees!

14.  Sources of data on previous spread  Liaison for information on pathogen, Elm host and vector biology  What control and detection is currently being done, and what was done in the past?  What outputs are required to feed into the rest of this project, and when?  What exactly would you like a model to test?