EPPO Bulletin (2011) 41, 217-225

M. Dupin, S. Brunel, R. Baker, D. Eyre and D. Makowski (2011)
A comparison of methods for combining maps in pest risk assessment: application to Diabrotica virgifera virgifera
EPPO Bulletin 41 (2), 217-225
Abstract: Host area, potential pest impact and probability of pest presence are frequently displayed on maps by pest risk assessors. These variables can be mapped separately, but it is also important to map combinations of these variables in order to define the area of potential establishment and the endangered area to assist decision-making processes. This paper presents different methods for combining maps, and discusses their advantages and disadvantages. Different methods are shown that can be used to combine maps depending on whether the individual maps were derived from continuous quantitative variables or from discrete variables. The authors suggest combining maps derived from continuous variables using simple mathematical equations in order to compute expected invaded areas and expected potential impacts. Maps derived from discrete variables (e.g. scores) can be combined using a risk matrix, but the results may be highly dependent on the chosen matrix. The practical interest of these methods is illustrated in a case study on Diabrotica virgifera virgifera. The authors recommend combining the original continuous variables when such variables are available. The combination of categories defined from continuous variables led to a loss of information and may decrease the values of the maps. Risk matrices should be used only if the individual variables are discrete and if the underlying continuous variables are not available.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): David Makowski, Dominic Eyre, Sarah Brunel

Research topic(s) for pests/diseases/weeds:
quarantine treatments/regulations/aspects
surveys/sampling/distribution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Diabrotica virgifera