Dynamic spatial network simulation accounting for multiple ecological factors provides practical recommendations for biosecurity early detection and rapid response (EDRR) strategies

BACKGROUND: Globally the spread of invasive pests is being facilitated by increased human mobility and climate change. Simulation modelling can help assess biosecurity strategies for early detection and rapid response (EDRR), but has struggled to account for important factors in the invasion process, such as spatial and temporal variability in habitat suitability and connectivity; population dynamics; and multiple dispersal pathways. We developed a novel dynamic spatial network simulation approach based on spatial network theory that enables integration of a wider range of spatio-temporal factors than previous studies, calibrated it against extensive historical trapping data, and applied it to comprehensively analyse the EDRR strategy for Oriental fruit fly (Bactrocera dorsalis; OFF) in northern Australia. RESULTS: Simulations indicated that the chance of OFF reaching the mainland in the next 20 years could be up to 20% under the current EDRR strategy, depending on how optimistic or pessimistic model assumptions are, and highlighted possible improvements to the EDRR strategy for further consideration. Simulations under optimistic assumptions indicate that transport via wind is most important in OFF reaching the mainland, but under pessimistic assumptions transport via people carrying infected fruit becomes more important. CONCLUSION: Our new dynamic spatial network simulation approach can account for a wide range of spatio-temporal ecological factors to provide practical real-world recommendations. At a minimum, this approach only requires weather and population data, both of which are available globally from a variety of free and open sources, making it broadly applicable to assessing the EDRR strategies in place for different species in other locations.