Estimating pest mortality in cold supply chains
Our team is working to develop rigorous, new methods to assess the contribution of commercial cold supply chains to reducing phytosanitary risks. Watch our animation for a quick overview of this research.
CSIRO – Biosecurity Risk Intelligence Explainer
[Music plays and an image appears of a split circle, and photos move through of CSIRO activities in either side of the circle, and then the circle morphs into the CSIRO logo]
[Animation image changes to show an aerial view of oranges landing on top of oranges, and then animation changes to show a small circle on an orange magnified to show grubs crawling in the circle]
Narrator: Shipping fruits and vegetables across the world is a delicate balancing act of keeping produce fresh while making sure no pests hitch a ride.
[Animation image changes to shows three crates of oranges below a large grub infested orange in a fridge, and a 16 day monitor can be seen counting up and down above the grub infested orange]
To manage pest risk, importing countries may require fruit to be treated at specific cold temperatures for fixed periods of time, and if the temperature rises above the required temperature before the treatment is completed, it may need to start again.
[Animation image changes to show four symbols in white circles of a clock encircled with an arrow, a hand with a coin, documents, and a winner’s ribbon with an arrow pointing down, and text appears: Time, Money, Paperwork, Quality]
This fixed approach costs time and money while having an impact on regulatory resources and produce quality.
[Animation image changes to show text: What if there was a better way?]
But what if there was a better way?
[Animation image changes to show various graphs for predicted mortality of oranges and grapefruit]
We’ve developed a flexible model that accurately and quickly predicts mortality for a wide range of pests, hosts and storage conditions.
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When compared with real world export data we can see that pest related risks are managed earlier than current trade protocols anticipate.
[Animation image changes to show a finger making selections on a website showing a shipment route, a temperature graph, the shipment cargo, and a fruit fly pest]
Our model enables fast tracked optimisation of new fruit and pest combinations and provides a more dynamic way of managing risk in traded produce.
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The result? Safe trade with lower costs, less waste and fresher produce.
[Music plays and image changes to show text on a blue screen: Biosecurity Risk Intelligence, Find out more research.csiro.au/prs]
[Image changes to show the CSIRO logo with text: CSIRO, Australia’s National Science Agency]
A new model to estimate pest mortality from cold exposure in the supply chain.
Cold treatment is a phytosanitary method that is commonly applied to manage cold sensitive, quarantine pests that may be carried via the trade of agricultural commodities.
Currently, phytosanitary cold treatment schedules do not take into account the contribution commercial supply chains may make to the cold-induced mortality of pests – yet, most fruit and vegetables are kept chilled to maintain freshness and quality from harvest through to retail markets.
Cold treatment schedules typically aim to achieve at least 99.99% mortality rate for the target pest and require horticulture consignments to be held at a set temperature for a specified duration. Development of a cold treatment protocol requires extensive technical data from rigorous, large-scale laboratory experiments that must be repeated for each pest and fruit combination.
To enable a more flexible approach, we are collaborating with university partners, regulators and industry on a diverse program of research to tackle different aspects of the challenge. Our work includes:
- Modelling mortality for pest fly species using publicly available data to predict how mortality is affected by temperature, exposure time, host fruit and developmental stage. Read more about this below!
- Quantifying the relationship between air temperature fluctuations and fruit pulp temperature. This may enable accurate prediction of pulp temperature of fruit in the cold supply chain using air temperature loggers that are increasingly used commercially to inform quality management. Our partners for this work are SuperCool and Escavox
- Creating a dashboard tool that allows supply chain partners to track in-transit cold mortality predictions through the commercial cool chain. This work is in collaboration with Escavox
- Empirically quantifying the effect of cold temperature exposure on Queensland fruit fly egg mortality. This research is in partnership with the Queensland University of Technology (QUT), Queensland Department of Agriculture and Fisheries (QDAF), and the Fresh and Secure Trade Alliance (FASTA). Key collaborators are Professor Peter Prentis and Kirra Sadzius (PhD student).
- Empirically quantifying critical thermal minimum of different insect pests. Our research collaborators are Dr Leigh Boardman at the University of Memphis, and United States Department of Agriculture (USDA).
Modelling time-temperature dependent pest mortality in fruit
We created a model that quantifies the relationship between pest mortality and cold temperature, exposure time, pest, pest life stage and host fruit. We hope that results from this work can help shift cold treatment practices from rigid, fixed temperature protocols with strict mortality targets to a more adaptable approach that accounts for existing commercial supply chain practices and infestation likelihood in produce.
To inform our model, we analysed 28 publicly available cold treatment studies for cold-sensitive pests. The model predicts the mortality of different pests over time, depending on key factors, including the type of pest (10 pest fly species), their developmental stage (eggs or larval stage), exposed temperature (0-7 °C), and host fruit (13 fruit types). We can readily extend the model with new data.
To learn more about the model, read our paper in the Journal of Pest Science:
Our model predictions indicate that some phytosanitary cold treatment schedules have large margins of error and are likely exceeding the target probit value. Longer, and colder, treatment schedules can add substantial cost and complexity to trade. It can also reduce fruit quality.
You can test our model and visualise the outputs with our calculator app:
Potential applications of our model include:
- Estimating pest mortality during commercial cold storage and transit
- Estimating the treatment time needed to achieve a target mortality rate at a given temperature for new pest-host-temperature combinations. These estimates can subsequently be empirically validated. This could greatly reduce the cost of undertaking studies to support treatment protocols. It may also be the only option for some pests that are difficult to culture.
- Supporting the use of treatment protocols already developed for other pest-host combinations which may reduce the need to undertake completely new empirical studies.
Looking ahead, this model could be adapted to guide phytosanitary risk management in a wider range of cold-sensitive pests in diverse hosts and commodities. Please contact us if you have datasets that you would like included.