Using edmaps & Zonation to inform multi-pest early-detection surveillance designs

Abstract

<p>Post-border surveillance of exotic pests and diseases for the purposes of early detection is a critical component of any effective and efficient biosecurity system. However, surveillance is often designed on a threat-by-threat basis, often resulting in a portfolio of geographically diverse surveillance networks that encompass a wide variety of land uses with varying degrees of biosecurity risk. As such, surveillance is prone to inefficiency, and is frequently costly and labour intensive. Recently, CEBRA in collaboration with the Department of Agriculture, Water and the Environment (DAWE) developed a pragmatic and transparent framework for estimating post-border establishment potential of priority plant pests and diseases. This framework, now packaged into an R package called edmaps, estimates post-border establishment potential as a function of three fundamental barriers to establishment: 1) propagule pressure; 2) climate suitability; and 3) host availability. With the development of edmaps, an opportunity now exists to systematically identify areas of high establishment potential shared across multiple threats. This in turn can be used to examine whether the spatial configuration of early detection programs - currently determined on a threat-by-threat basis -can be consolidated to areas of shared high establishment potential, and thus, reduce logistical costs associated with surveillance.</p> <p>In this project, we examine how threat-specific edmaps output may be used in combination with the software Zonation to inform priority areas for early-detection surveillance across multiple threats. To achieve this we used edmaps to produce post-border establishment potential maps for 10 plant pests, 4 plant pathogens and 9 exotic pathogen vectors identified by DAWE as priority threats.</p> <p>We found that Zonation can be used with threat-specific early detection maps to inform multi-threat surveillance prioritisation. Moreover, based on preliminary pathway inputs supplied by DAWE, our analyses suggest that by moving from a threat-specific prioritisation (i.e. using individual threat early detection maps) to a multi-threat prioritisation, one could geographically consolidate surveillance with only a marginal reduction in the threat-specific establishment likelihood captured per unit area surveyed - especially if the geographic distribution of establishment likelihoods is similar across threats.</p> <p>Outputs included in this report are example multi-threat prioritisation maps derived from two Zonation algorithms - core-area Zonation (CAZ) and Additive Benefit Function (ABF). These maps are constructed at both national and metropolitan extents. An example of the metropolitan maps can be seen below (Figure 0.1).</p> <p>Also accompanying this report as a separate file is an example interactive map of a core-area Zonation multi-threat prioritisation (top_caz_national.html). This file allows readers to interactively examine an output of zonation that has identified the top 5,000 ranked priority locations across Australia for multi-threat surveillance. Users can zoom in on particular flagged locations and see the break down of threat-specific establishment likelihood captured and priority ranking locations. Also included as a separate file is the edmaps input file (parameters.xlsx) used to construct the threatspecific establishment likelihood maps. Raw output files can be supplied on request.</p>