Candice Bartlett & Andrew Cox, Invasive Species Council

Prevention is the best medicine; a saying that applies to many things, including invasive species.
Stopping new invasive species arriving and establishing in Australia is arguably one of the most cost-effective ways to protect our native species from further threats.

As invasive species grow and spread, their potential impacts escalate, and so too does their cost of management. The invasion curve, which describes the ecological process of arrival and spread of an invasive species also neatly describes the rising costs of impacts (see figure below).

Once a pest is established and the point of eradication feasibility is passed, the costs to mitigate its impact on the environment become embedded in state and federal budgets in perpetuity. For example, introduced pests are believed to cost the Australian economy between $720 million and $1 billion a year (NRC 2016 State-wide review of pest animal management).

The release of biological control agents can provide relief for some established pests, as famously occurred for prickly pear and rabbits, but they cannot be relied upon.

Logically, commitments to funding prevention, eradication and containment strategies should exist to slow and stop the burden of more and more pests establishing and spreading.

An effective biosecurity system relies on knowing your enemy. Whilst the risks to Australia’s agriculture industry and human health are well studied and understood, there is a large knowledge gap when it comes to environmental biosecurity threats across animalia classes.

The species invasion curve describes the ecological process of arrival and spread of an invasive species, and the cost of managing the impacts. Credit: Invasive Species Council, based on version by Agriculture Victoria.

Recent research, conducted by Monash University in collaboration with the Invasive Species Council (funded by the Ian Potter Foundation), aims to close this gap for invasive insects.

The Risks and Pathways Project set out to identify insect species from other countries that, if they ever reach Australia, have the potential to cause great harm to our natural environment. A stocktake of invasive insects causing environmental harm elsewhere in the world was compiled, their pathways mapped and the International Union for the Conservation of Nature’s (IUCN) framework for the Environmental Impact Classification of Alien Taxa applied to assess the severity of each species’ ecological impacts.

A national priority list of 247 potentially harmful insect invaders was identified. Prevalent pathways by which these invaders may arrive include contamination of imported plants and nursery material and the timber trade.

Further work conducted by the agricultural research body ABARES looked at all exotic environmental pests and disease that could establish in Australia and will be used by federal and state governments to create a final priority list to inform environmental biosecurity activities. The results of the Risks and Pathways Project will also be considered.

Such research is a necessary foundation for a strong environmental biosecurity system. Understanding the potential risk species and invasion pathways can build the capacity of the system to recognise and respond through the development of early detection systems, emergency response plans for when incursions occur and being able to address the potential environmental invaders at their source.

Had we detected red fire ants shortly after they established in the Brisbane suburb of Wacol, we are unlikely to have needed the roughly $800 million that will have been spent by 2027 on eradication. The ants were thought to have been detected more than ten years after their arrival and, at their worst, spread to cover an area of 400,000 ha.

The Invasive Species Council has been calling for a greater investment in research to support environmental biosecurity at all stages of the invasion curve: prevention, eradication, containment and control, covering all categories of invasive species – vertebrates, invertebrates, fungi, weed and marine threats. Ideally, this would be funded through a new hub of the federal government’s National Environmental Science Program, which is currently under review.

Marine pests are notoriously hard to eradicate once they establish in Australia’s marine environment, so research focused on prevention is essential. This could include
studies that more precisely identify the arrival pathways of contaminated ships or untreated ballast waters that will help with measures to ensure those pathways are cleaned.

Research into containment can help slow or halt the spread of an invasive species. The six species of feral deer established in Australia that presently cover less than 10% of Australia are projected to eventually cover the entire mainland continent. Research is needed to better model this invasion process and improve the control techniques needed to contain the spread of feral deer and avert a major transformation of native vegetation from deer grazing.

Social research is also important to advance property-level control efforts for emerging widespread pests and weeds. Unless there is a good understanding of the motivating factors of busy land managers, then we cannot expect education programs to be effective.

Ultimately, our ability to protect Australia’s unique environments into the future will rely on our capacity to combat invasive species at all stages of the invasion curve.

For more information, contact the Invasive Species Council here.

Read more from the 2020 March ESA Bulletin.

Banner image: Early detection and response to invasive species, such as red fire ants, will help reduce both ecological and financial costs. Credit: Wikimedia Commons.