RISK ASSESSMENT FOR ESTABLISHMENT OF AN
INTRODUCED PEST:
In Face of a Changing Environment
J.A. LOGAN 1, J. RÉGINÈRE2, D. R. GRAY3, S. A. MUNSON4
1
USDA Forest Service, Forest Sciences Laboratory, 860 N 1200 E Logan, Utah 84321; 2Canadian Forest Service, Laurentian
Forestry Centre, PO Box 3800 Sainte-Foy, Quebec, Canada G1V 4C7; 3Canadian Forest Service, Atlantic Forestry Centre,
PO Box 4000 Fredericton, NB, Canada E3B 5P7, 4USDA Forest Service, Forest Health Protection, 4746 S. 1900 East, Ogden,
UT 84403
GYPSY MOTH
1869
Introduced Species – Basic Questions
Is it a real threat?
(1) Is an introduction potentially
damaging?
(2) What is the likelihood of
Introduction?
(3) If introduced, what is the probability of
becoming established?!
Utah Native Forest Hosts
ASPEN
GAMBEL
OAK
MAPLE
The Basic Dilemma of Assessing the Risk
Of a Detected Introduction
On one hand, we clearly do not want yet another
exotic pest in the already beleaguered forests of
the Interior Mountain West
On the other hand, it is unwise to waste seriously
limited resources responding to something that is
in fact not a serious threat.
Gypsy Moth Landscape Model
Gray DR, Ravlin FW, Braine JA. 2001. Diapause in the gypsy moth: A model of inhibition
and development. J. Insect Physio. 47: 173-184
Logan, J. A., R. A. Casagrande, and A. M. Liebhold. 1991. A modeling environment
for simulation of gypsy moth larval phenology. Environ. Entomol. 20: 1516-1525.
Régnière, J., B. Cooke, and V. Bergeron. BioSIM: a computer-based decision
support tool for seasonal planning of pest management activities; User's Manual.
Canadian Forest Service Information Report LAU-X-155, 1996
ESSENTUAL DATABASES
Utah GAP Data
Climate Change Scenarios
National
Center for
Atmospheric
Research
Weather Data – Daily Resolution – M/m Temperature + Precipitation
Spatial Resolution => 0.5 Arc Degree
Historic (1895-1993) and Transient Data (1993-2100)
Scenario – 1%/yr 1993-2100 => CO2 doubling in 70 yrs –
(IPCC = 37 years CO2 equivalent)
mean US increase in CO2 (1991 –2001) = 1.56%; US-DOE 2002 Report
Procedure for model evaluation
Probability of establishment (Thermal Requirements)
break diapause
thermal energy to complete life cycle in a season
appropriate time of emergence
Parametric bootstrapping
Climate not weather => 30 yr weather normal
Sample 50 years of weather from normals
Run model for 20 generations (for each 50 year’s weather – check if
population persisted (0, 1)
Compute proportion of 50 years of samples that became established
Map the proportion (probability) across the landscape
Proportion
Aspen in Black
1915
Black > 0.5P Thermal
White < 0.5P Thermal
~Hazard
Green Aspen in < 0.5P
Red – Aspen in > 0.5P
~Risk
1915
1925
1935
1945
1955
1965
1975
1985
1995
2005
2015
2025
2035
2045
2055
2065
2075
2085
2085
Consequences of Global Warming
1965
1965
2055
Aspen
Not enough thermal energy under
current climate (pre-CC)
Thermal requirements met for most
aspen by mid century
Malacosoma (Native Defoliator)
Malacosoma + GM = Ecological Disaster ??
Oak
Typically too Xeric (pre-CC) – marginal survival ??
GCM prediction of increased precipitation
Improve habitat directly
reservoir from Aspen
Conduit from metropolitan areas to Aspen
2055
Summer 2003 – Uinta Mountains
2070-2100
GYPSY MOTH TRAP RECOVERIES 2004
Probability Classes Based on 1980 – 2010 Normals Weather
P = 0.0 – 0.2
P = 0.2 – 0.4
P = 0.4 – 0.6
P = 0.6 – 0.8
P = 0.8 – 1.0
Salt Lake City Trap Recovery
Prevailing Wind
~7.5 mi.
CONCLUSIONS
(1) Presently – any detected introduction is treated the same –
one size fits all
(2) Often overreaction and subsequent unjustified expenditure
of resources (so far!)
(3) Inclusion of risk in a changing environment
(4) Planning tool – where and when to place monitoring traps