Biosecurity for market access | May 2025

Some of the worlds’ most serious horticultural pests of quarantine concern – such as fruit flies – are cold sensitive. Cold treatment is a common method used to manage the risk of moving these pests in international trade.

But how much mortality already occurs in commercial cold supply chains?

That is a question our team is currently addressing with collaborators at Escavox, SuperCool, QUT and the University of Memphis. Our research includes:

• developing a predictive model of pest mortality under cold exposure,
• combining this model with commercial supply chain data to track pest mortality in real supply chains, and
• empirical work to validate and further improve our model.

You can read more about this work here.

Our work shows there is potential to shift the use of cold to manage pests from highly regulated, fixed temperature treatments with strict mortality requirements to a more flexible approach that accounts for commercial supply chain conditions as well as infestation likelihood in produce. Further collaborative research may help build confidence amongst trading partners to simplify future market access arrangements based on cold exposure. This shift could reduce the cost and complexity of managing phytosanitary risks, whilst improving the quality and shelf life of produce.

Chill out! Using predictive models to guide smarter cold treatments

The foundation for our work was to develop a model that – for the first time – can predict the effect on mortality rate of pest (10 species of pest flies), developmental stage (eggs or larvae), host fruit (13 types), exposed temperature (0-7°C) and exposure time. We fitted our model from data extracted from 28 published studies.

Our modelling shows that the effect of host on pest mortality rate is relatively minor. It also indicates that some cold treatment schedules have a high margin of error – meaning that some treatments may exceed the target probit value.

Potential applications for our model include:

• estimating and recognising pest mortality in commercial cold chains, and
• generating modelled estimates of treatment requirements for novel pest-host-temperature combinations that may help optimise empirical trials.

You can read our published paper and also explore the model through the app on our website.

We can readily incorporate additional data sets (e.g. species, hosts, temperatures) into our model to make it even more powerful. Please contact us if you are interested in collaborating in this way.

Some other highlights

We continue to give presentations and workshops. Some recent ones include:

• A presentation to the Canadian Food Inspection Agency Research Seminar Series on “Risk science to support the management of phytosanitary risk in a modern world”.
• Workshopping the Menu of Measures with the IPPC Technical Panel on Commodity Standards (TPCS) while they were meeting in Canberra. This generated a lot of enthusiasm and excellent questions and discussion.
• A presentation to the USDA on non-destructive pest detection which covered our ongoing work on optical detection, X-rays and electronic noses

Please contact us if you’d like a deeper diver into our work and potential applications of it, either in-person or on-line.

Innovation through collaboration

Our team aims to enhance the science, technology and regulation underpinning biosecure trade. Through these updates, we aim to connect with like-minded researchers, policy makers, industry members, ag-tech providers, and research organisations – so please do share this with others in your network.

You can also find previous Biosecurity for market access updates here.

We are interested to hear about your work in this field, or any feedback about our research. You can subscribe to these updates or contact our team at phytoriskscience@csiro.au