New resources & developments improving detection of vegetable leafminer

The RD&E program for the control, eradication and preparedness of vegetable leafminer (MT16004) continues to improve the identification and detection of vegetable leafminer in Australia. Led by research provider, cesar, the project aims to raise awareness and protect against the spread of vegetable leafminer throughout Australia’s key growing regions.

First detected in 2015, the vegetable leafminer (Liriomyza sativae) is a pest capable of infesting a variety of horticultural crops in Australia. The fly inhibits plant growth by laying eggs inside plant leaves and stems, while maggots tunnel within and create tracks or mines, which get bigger as they grow.

The industry impact of the vegetable leafminer could be significant, such as reducing the plant’s market value, and creating stricter import and domestic trade restrictions in areas of Australia where the pest is absent.

The project team has conducted a series of leafminer damage surveillance trials in order to measure the detectability of leafmines in crops. The first of the mock trials were held in Victoria last year, bringing together growers, agronomists, and wider industry professionals to undertake short survey walks of crop rows where simulated leafmines were hidden.

Data from the trials was validated by running a second survey walk in gardens and weeds in the Torres Strait; comparing the detectability of simulated mines with real mines created by the VLM. Members from the Northern Australia Quarantine Strategy (NAQS), along with other Torres Strait groups, participated in these damage survey trials.

Data recorded from both trials is enabling cesar to develop a statistical based recommendation for how long surveyors should spend per area in order to have a high chance of detection with low-level leafminer damage. The data is suggesting that the minimum effort spent for a strong chance of detection should be 1 minute per 1 to 4 meters of area. Due to this being such a time intensive requirement, the project team needs to explore the trade-off between high search intensity and greater area coverage.

An Update: 2019 Surveillance Trials

To test the survey guidelines from last year’s trial, the project team went back to the Torres Strait in May this year, visiting Thursday Island where they ran another surveillance activity at the annual Training Conference for NAQS biosecurity officers.

NAQS officers from across the Torres Strait were in attendance, which provided a great opportunity to test survey guidelines developed from last year’s trials. The officers were split into two groups, each conducting a survey for leafmines in the local community garden. The first group received no surveillance instructions, but the second were instructed to follow the 1 minute per 1 to 4 meters of area guideline. Although in the very early stages of analysis, the results on improved detection appear very promising.

The MT16004 project team would like to acknowledge the members of NAQS, who have been critical to this project by providing their extensive knowledge, technical and practical advice, and experimental support.

What’s new?

A gardener surveillance guide was developed on exotic leafminer for the Torres Strait and Northern Peninsula Area, as well as an informational guide about biological control of leafminer in these regions. These resources were distributed to community gardeners in the Torres Strait and Northern Peninsula Areas, during the May trip.

A first draft of a surveillance guide for growers is now available for feedback at AUSVEG’s MT16004 project page. While the guide is currently in draft form, the team at cesar are keen to hear grower insights on best survey techniques, which will help improve the usefulness, relevance and accessibility of this guide. If you have any feedback, please get in touch with Dr Elia Pirtle at epirtle@cesaraustralia.com.

What’s coming up?

Through analysis of the more recent trial results, the team will explore the implications of the high effort required to spot leafmines. For example, exploring how to increase detectability with short, high intensity searches, based on the 1 minute per 1 to 4-meter guideline, that are dispersed across wider areas. This will add more clarity to the survey instructions within the grower surveillance guide for VLM.

Keep an eye out for more project updates, and resource developments to come!

What resources are already available?

This project has focused on developing a series of educational resources for monitoring and eradication, as well as aiming to better model and understand its spread. By continuing to raise awareness and unearth new findings, this project maintains a primary focus on the development of educational resources for both the industry and community; ensuring they are aware of and informed about, how to identify and report detections of vegetable leafminer.

Resources that have been developed through this program include: an educational video for growers and the public, a podcast on InfoVeg Radio, an awareness poster, educational flyer, and a VLM interactive map tool, which identifies high risk regions.

For more information on the project, head to: https://ausveg.com.au/biosecurity-agrichemical/biosecurity/mt16004/

RD&E program for the control, eradication and preparedness of vegetable leafminer (MT16004) has been funded by Hort Innovation using vegetable and nursery industry levies, with funds from the Australian Government.