Haight, Robert G.

Homans, Frances R.

Mehta, Shefali V.

English

Research Papers in Economics

The value of information in invasive species management
ShefaliV. Mehta,1 Robert G. Haight,2 and Frances R. Homans1
1Department of Applied Economics, University of Minnesota,  2 USDA Forest Service Northern Research Station
OBJECTIVE
► Invasive species exact a growing toll on ecosystems and cause substantial 
economic losses.
►Invasive species management is hindered by the uncertainty inherent to the 
invasion process, or the population dynamics of the species.
► Research provides one venue for acquiring information, subsequently 
lessening uncertainty.  However, allocating resources to research detracts 
from other key management activities.
► We assess the value of information (VOI), or the value of reducing 
uncertainty, in invasive species management.  VOI can help identify the 
areas which yield higher returns from research investments.
ACKNOWLEDGEMENTS The authors conducted this research with a grant from the USDA 
Northern Research Station.
REFERENCES   Haight, R.G., S.V. Mehta, F. R. Homans, and R. C. Venette. 
2007. Optimal Search Strategies for Detecting Invasive Species. 
Working paper.
CONTACT Corresponding author: S.V. Mehta, meht0038@umn.edu
MODEL
►We analyze the VOI in the model from Haight et al. (2007) which evaluates 
detection strategies for invasive species from the perspective of a 
government agency manager monitoring a land parcel.
►The manager chooses the search rate, s, to minimize the expected 
discounted cost of management, E(MC) (figure on left), as a function of 
several parameters (table on left).
►One measure of the value of reducing uncertainty is the expectedvalue of 
perfect information (EVPI) which represents the potential gain from 
acquiring full knowledge about a parameter.
►Assume the species’ growth rate, gi, has several potential values, i = 1,…,n, 
depending on the state of the world and each state has some probability of 
occuring, p(gi). The manager chooses from a number of search intensities,  j 
= 1,…,m, and faces management costs, MC(sij), The EVPI is the following:
which is the difference between the optimal expected management costs 
and the expected management costs under perfect information.
DISCUSSION
►Biological parameters, particularly the growth rate, tend to have a higher 
value of information than the economic parameters based on this model.  
►However, the EVPI varies depending on the characteristics of thespecies.  
Species with high arrival or growth rates (Case 2) do not necessarily gain 
from additional research focusing on the biological parameters. Targetted 
research for species with relatively lower biological parameters(Cases 1 
and 3) could yield potential gains for the land manager.
►Future research should build upon this information to identify the optimal 
resources to allocate to research vis-à-vis other management activities.
$0
$1,000
$2,000
$3,000
$4,000
$5,000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1
Search intensity, s
C
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s
t
s
 
(
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s
a
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d
s
)
Case 2 -s *= 1
Case 1 -s *= 0.65
Boll Weevil (left), Asian Longhorned Beetle (right)
Pictures from Alton N. Sparks, Jr., University of Georgia, Bugwood.org; USDA APHIS, Plant Health website
0.45 1 0.65 Optimal search intensity
6.0 0 3.7 Expected value of 
perfect information
0.1 0.1 0.1 Discount rate
0.11 0.11 0.11 Expectation of growth 
rate
0.22 0.4 0.22 Arrival rate
300 500 500 Eradication costs (`000s)
100 100 100 Search costs (`000s)
Case 3 Case 2 Case 1 Cases
Parameters
Parameter values for cases representing different invasive 
species
Invasive species cases: Case 1 is a species with high eradication costs and a 
moderate arrival rate.  Case 2 is a similar species but with a higher arrival rate.  Case 
3 represents a species with moderate eradication costs and a moderate arrival rate.  
Those cases with EVPI > 0 could benefit from research focusing on the growth rate.
Expected management costs for invasive species cases
Case 3 -s *= 0.45
Expected management costs: This figure plots the expected management costs over 
the search intensity, s, for each case in the table below.  The optimal search intensity, 
s* (denoted by the star), is the search rate that minimizes the expected costs.
Cactus Moth (left), Emerald Ash Borer (right)
Pictures from Dale Habeck, Bugwood.org; David Cappaert, MichiganState University, Bugwood.org 
Hemlock Woolly Adelgid (left and center), Coffee Berry Beetle (right)
Pictures from USDA Forest Service, Northeastern Area, Photo Gallery; CT Agricultural Experiment Station Archives, CT Agricultural 
Experiment Station, Bugwood.org; Eric Erbe, USDA Agr. Res. Svc.,Bugwood.org 

The Value of Information in Invasive Species Management

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