Predicting Argentine ant spread over the heterogeneous landscape using a spatially explicit stochastic model

Abstract

The characteristics of spread for an invasive species should influence how environmental authorities or government agencies respond to an initial incursion. High-resolution predictions of how, where, and the speed at which a newly established invasive population will spread across the surrounding heterogeneous landscape can greatly assist appropriate and timely risk assessments and control decisions. The Argentine ant (Linepithema humile) is a worldwide invasive species that was inadvertently introduced to New Zealand in 1990. In this study, a spatially explicit stochastic simulation model of species dispersal, integrated with a geographic information system, was used to recreate the historical spread of L. humile in New Zealand. High-resolution probabilistic maps simulating local and human-assisted spread across large geographic regions were used to predict dispersal rates and pinpoint at-risk areas. The spatially explicit simulation model was compared with a uniform radial spread model with respect to predicting the observed spread of the Argentine ant. The uniform spread model was more effective predicting the observed populations early in the invasion process, but the simulation model was more successful later in the simulation. Comparison between the models highlighted that different search strategies may be needed at different stages in an invasion to optimize detection and indicates the influence that landscape suitability can have on the long-term spread of an invasive species. The modeling and predictive mapping methodology used can improve efforts to predict and evaluate species spread, not only in invasion biology, but also in conservation biology, diversity studies, and climate change studies.

Relative roles of climatic suitability and anthropogenic influence in determining the pattern of spread in a global invader

“…42) for the expansion of the Argentine ant at regional and local scales, not only among countries, is needed to assess the geographic dimensions of the invasion over time in fine detail. This type of information is crucial to anticipate the rate at which Argentine ants will spread and the areas most likely to be invaded (28,43). Finer-resolution data on patterns of commerce, which incorporate a strong historical perspective, are needed to provide a more rigorous test of the role of propagule pressure at global scales.…”

“…Many studies have examined the distribution and dispersal pathways of this invasive ant (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) and described the range limits at regional and global scales (20,(23)(24)(25)(26)(27)(28). However, most of these studies relied on simple environmental niche models or described the current distribution of the species using only partial records.…”

Applying a spread model to identify the entry points from which the pine wood nematode, the vector of pine wilt disease, would spread most rapidly across Europe

“…Increasingly, studies have shown that human-mediated dispersal plays an important role in the long-distance dispersal of invasive terrestrial invertebrates (e.g., Gilbert et al 2004;Muirhead et al 2006;Lippitt et al 2008;Pitt et al 2009;Robinet et al 2009). Since these long-distance jumps have a low probability of occurrence and are difficult to predict, the most appropriate models to describe this type of spread are stochastic although hundreds of replicate simulations may be required to obtain a representative estimate of potential spread (Pitt et al 2009;Robinet et al 2009). …”

Quantifying uncertainty in pest risk maps and assessments: adopting a risk-averse decision maker’s perspective

“…Spatial stochastic models have been increasingly used for assessing risks of ecological invasions (Rafoss 2003, Cook et al 2007, Pitt et al 2009, Muirhead et al 2006, 2010. We applied a pathway model that used vector-based information stored in the NRRS database to predict movements of recreational travellers to federal campgrounds in the U.S., including cross-border visits from Canada.…”