Modelling tropical fire ant (Solenopsis geminata) dynamics and detection to inform an eradication project
Invasive species threaten endangered species worldwide and substantial effort is focused on their control. Eradication projects require critical resource allocation decisions, as they affect both the likelihood of success and the overall cost. However, these complex decisions must often be made within data-poor environments. Here we develop a mathematical framework to assist in resource allocation for invasive species control projects and we apply it to the proposed eradication of the tropical fire ant (Solenopsis geminata) from the islands of Ashmore Reef in the Timor Sea. Our framework contains two models: a population model and a detection model. Our stochastic population model is used to predict ant abundance through time and allows us to estimate the probability of eradication. Using abundance predictions from the population model, we use the detection model to predict the probability of ant detection through time. These models inform key decisions throughout the project, which include deciding how many baiting events should take place, deciding whether to invest in detector dogs and setting surveillance effort to confirm eradication following control. We find that using a combination of insect growth regulator and toxins are required to achieve a high probability of eradication over 2 years, and we find that using two detector dogs may be more cost-effective than the use of lure deployment, provided that they are used across the life of the project. Our analysis lays a foundation for making decisions about control and detection throughout the project and provides specific advice about resource allocation.
KeywordsAshmore Reef Eradication Invasive species Invertebrates Optimal detection Stochastic modelling Monitoring
We thank Kirsti Abbott, Shane Baylis, Michael Bode, Jake Ferguson, Ben Hoffmann, Michael McCarthy and José Lahoz-Monfort for insight and discussion. This research was jointly funded by the Department of the Environment and Energy (formerly DSEWPaC) and Monash University. Christopher Baker was funded by The University of Melbourne, the National Environmental Research Project Environmental Decisions Hub and is the recipient of a John Stocker Postdoctoral Fellowship from the Science and Industry Endowment Fund. This research was conducted at Ashmore Reef Commonwealth Marine Reserve under Permit No. 006-ARRR-110421-01. The authors wish to thank the relevant staff at the Department of the Environment, especially Anna Farnham, Rod Atkins and Miranda Carver. The authors have no conflict of interest to declare.
- Bellio MG (2007) A preliminary ecological risk assessment of the impact of tropical fire ants (Solenopsis geminata) on colonies of seabirds at Ashmore Reef. Darwin NT, CanberraGoogle Scholar
- Clarke RH, Carter M, Swann G, Thomson J (2011) The status of breeding seabirds and herons at Ashmore Reef, off the Kimberley Coast, Australia. J R Soc West Aust 94:365–376Google Scholar
- Efron B, Tibshirani RJ (1994) An introduction to the bootstrap. CRC Press, Boca RatonGoogle Scholar
- Hodgson JC, Clarke RH (2014) A review of the tropical fire ant Solenopsis geminata pilot control program at Ashmore Reef Commonwealth Marine Reserve. Monash University, School of Biological Sciences, MelbourneGoogle Scholar
- Hodgson JC, Abbott KL, Clarke RH (2014) Eradication plan - Tropical Fire Ant Solenopsis geminata at Ashmore Reef Commonwealth Marine Reserve. Monash University, MelbourneGoogle Scholar
- Jarrad FC, Barrett S, Murray J et al (2011) Improved design method for biosecurity surveillance and early detection of non-indigenous rats. N Z J Ecol 35:132–144Google Scholar
- Lei M, Yin Q, Yao X (2015) A method for UAVs detection task planning of multiple starting points. In: 2015 IEEE international conference on mechatronics and automation (ICMA). pp 947–951Google Scholar
- May RM (2001) Stability and complexity in model ecosystems. Princeton University Press, PrincetonGoogle Scholar
- Ramsey DSL, Parkes JP, Will D et al (2011) Quantifying the success of feral cat eradication, San Nicolas Island, California. N Z J Ecol 35:163–173Google Scholar
- Veitch CR, Clout MN (2002) Turning the tide: the eradication of invasive species. In: Proceedings of the international conference on eradication of island invasives. IUCN SCC Invasive Species Specialist Group, IUCN, Gland, Switzerland and Cambridge, UKGoogle Scholar