Biol Invasions (2014) 16:401–414 DOI 10.1007/s10530-013-0529-5 ORIGINAL PAPER Determinants of successful arthropod eradication programs Patrick C. Tobin • John M. Kean • David Maxwell Suckling • Deborah G. McCullough • Daniel A. Herms • Lloyd D. Stringer Received: 17 December 2012 / Accepted: 25 July 2013 / Published online: 27 August 2013 Ó Springer Science+Business Media Dordrecht (outside the USA) 2013 Abstract Despite substantial increases in public target species, method of detection, and the primary awareness and biosecurity systems, introductions of feeding guild of the target species. The outcome of non-native arthropods remain an unwelcomed conse- eradication efforts was not determined by program quence of escalating rates of international trade and costs, which were largely driven by the size of the travel. Detection of an established but unwanted non- infestation. The availability of taxon-specific control native organism can elicit a range of responses, tools appeared to increase the probability of eradica- including implementation of an eradication program. tion success. We believe GERDA, as an online Previous studies have reviewed the concept of erad- database, provides an objective repository of infor- ication, but these efforts were largely descriptive and mation that will play an invaluable role when future focused on selected case studies. We developed a eradication efforts are considered. Global Eradication and Response DAtabase (‘‘GER- DA’’) to facilitate an analysis of arthropod eradication Keywords Detection Á Eradication Á Invasive programs and determine the factors that influence species management Á Non-native pests eradication success and failure. We compiled data from 672 arthropod eradication programs targeting 130 non-native arthropod species implemented in 91 Introduction countries between 1890 and 2010. Important compo- nents of successful eradication programs included the Despite increased attention and enhanced regulatory size of the infested area, relative detectability of the efforts, non-native organisms continue to become P. C. Tobin (&) D. M. Suckling Á L. D. Stringer Forest Service, U.S. Department of Agriculture, Northern Plant Biosecurity Cooperative Research Centre, Canberra, Research Station, Morgantown, WV 26505, USA ACT, Australia e-mail: [email protected] D. G. McCullough J. M. Kean Departments of Entomology and Forestry, Michigan State AgResearch Limited, Ruakura Research Centre, East University, 243 Natural Science Building, East Lansing, Street, Private Bag 3115, Hamilton 3240, New Zealand MI 48824, USA D. M. Suckling Á L. D. Stringer D. A. Herms The New Zealand Institute for Plant & Food Research Department of Entomology, Ohio Agricultural Research Limited, Private Bag 4704, Christchurch 8140, and Development Center, The Ohio State University, New Zealand 1680 Madison Ave., Wooster, OH 44691, USA 123 402 P. C. Tobin et al. established in new regions, primarily as a result of the Despite an often negative perception of the viability increasing volume and shifting patterns of interna- of eradication efforts, the long-term benefits of tional travel and trade (Aukema et al. 2010; Hulme successful eradication typically outweigh the costs of et al. 2008; Levine and D’Antonio 2003; Reichard and the program (Brockerhoff et al. 2010). A dispassionate White 2001). Many countries maintain border biose- analysis of the factors that have influenced the success curity systems designed to detect and intercept species of eradication programs could have tremendous arriving through trade and travel routes before these practical utility and serve to inform and improve the organisms can become established. However, the decision-making process. In this paper, we sought to sheer volume of global trade and travel, and the assess the importance and quantify the roles of various diversity of invaders, makes it inevitable that some factors that affect eradication success of non-native species will evade detection at ports-of-entry, and a arthropods by using a global database comprised of portion of those species will become established successful and failed eradication programs. (Brockerhoff et al. 2006; Liebhold et al. 2012; Previous reviews of attempts to eradicate non- National Research Council 2002; Work et al. 2005). native pest species have been largely descriptive and When a non-native species is detected, consequent consist of either narratives of selected programs or management options range from taking no action to generalized examples (e.g., Dahlsten and Garcia 1989; implementing an eradication effort. The concept of Graham and Hourrigan 1977; Myers et al. 1998; eradication is beguiling; it suggests a final and Myers et al. 2000; Popham and Hall 1958). In a recent permanent solution to the threat of an invader. In quantitative study, Pluess et al. (2012a) used General- practice, however, the deliberate extirpation of a target ized Linear Mixed Models to analyze a database of species can be challenging, both biologically and 136 eradication campaigns against a variety of terres- economically (Myers et al. 2000; Popham and Hall trial invertebrates, plants, and plant pathogens. They 1958). Moreover, because propagule pressure tends to reported that local campaigns were more likely to be positively associated with establishment success succeed than regional or national programs. Other (Drake and Lodge 2006; Lockwood et al. 2005; factors, including the level of biological information Simberloff 2009), successful eradication of a target available about the target species, insularity, and species could be ephemeral if propagule pressure is reaction time did not significantly influence the rate of not mitigated. eradication success. In a subsequent classification tree Past work has highlighted a number of conditions analysis based upon 173 eradication campaigns, thought to be critical for an eradication program to be reaction time was identified as an important determi- successful (e.g., Brockerhoff et al. 2010; Dahlsten and nant of eradication success, along with habitat type Garcia 1989; Hoffmann et al. 2011; Knipling 1966; and target taxon (Pluess et al. 2012b). The authors also Myers et al. 2000; Pluess et al. 2012a; Pluess et al. highlighted the dearth of information on program costs 2012b; Simberloff 2003; Simberloff et al. 2005). and other socioeconomic factors in their data, which Attributes include the ability to detect, identify and are generally considered to play major roles in the monitor an invader, understanding the potential risks outcome of eradication campaigns. and impacts posed by the invader, and having the tools To expand our understanding of the determinants of to respond rapidly and effectively. Policy related successful eradication programs, we acquired data attributes include the authority to intervene or take from 672 eradication programs against arthropods that action on public and privately-owned lands, procure- were undertaken around the world between 1890 and ment of necessary funds, and the commitment and 2010. These data were compiled into a web-based political will exhibited by affected stakeholders and Global Eradication and Response DAtabase (‘‘GER- the public in support of the eradication effort. As a DA,’’ Kean et al. 2013) that we developed and hereby result of these collectively complex and daunting present. Although GERDA also currently contains requirements, and the notoriety of a few spectacularly data on eradication programs targeting other taxa (e.g., failed attempts, the scientific and regulatory commu- nematodes, fungi, molluscs), we focused our analysis nity has often viewed eradication with pessimism specifically on arthropods to avoid comparing taxa (e.g., Dahlsten 1986; Dahlsten and Garcia 1989; that differ vastly in their respective biology and Myers et al. 1998; Whitten and Mahon 2005). invasion ecology. In addition to the current analysis 123 Determinants of successful arthropod eradication programs 403 presented in this paper, a long term goal of GERDA is program. Pest management programs were to provide a repository to facilitate the ongoing excluded if the objectives included reduction or collection and transfer of knowledge among biosecu- containment, but not local extinction, of the target rity practitioners and the scientific community. population. One of the greatest technical chal- lenges of any eradication campaign is demon- strating the absence of the very last target individual; mere pest reduction, rather than com- Materials and methods plete extirpation, thus omits one of the most important aspects of eradication. However, we did Compilation of data encounter a few cases where eradication was fortuitously achieved following large-scale pest We compiled a database of eradication attempts reduction programs. We included data from these targeting a total of 130 non-native arthropod species cases because they provided valuable information implemented in 91 countries (Fig. 1). The species regarding the effort and expenditures required to targeted for eradication were generally defined as achieve eradication. Also, some newly-discov- actionable pests in that their expected economic and ered incursions were managed initially for con- ecological harm was sufficiently great to warrant an tainment while information was gathered to eradication attempt. We acquired data from a variety evaluate potential costs, benefits, and feasibility of sources including scientific literature, government of eradication. Such cases were not included documents and press