Management strategy for serpentine leafminer, Liriomyza huidobrensis (MT20005)

Surveys of grower properties have been continuing in the Northern Territory for American Serpentine Leafminer (ASLM) in the regions they are currently found. The confirmed presence of SLM in potato crops in the Lockyer Valley is of concern, due to the level of damage being seen last season for the first time.  Growers and agronomists are now aware of its impact and will be more vigilant this coming season. 

A workshop for predominantly agronomists on the Granite Belt attracted ten agronomists.  These agronomists cover over 90 per cent of growers in this region.  The evaluation forms that came back from all ten indicated that the majority improved their understanding of SLM and are likely to change how they look for and manage SLM in the future.  The use of microscopes to show the range of parasitoids and SLM life cycle stages, was particularly well received and could be used in future workshops. 

Specimens of both SLM and ASLM are continually being sent to both NSW DPI molecular group and Cesar Australia for identification and testing using the LAMP primers developed for this project and using the qPCR assays developed by Cesar Australia.  The qPCR works effectively in the laboratory on flies, larvae and empty mines excised from leaves, whereas the LAMP tests will work both in the lab and in the field on larvae, pupae and adults of SLM.  In total, 61 samples have been received and processed by Cesar, the majority from QLD.  25 samples were sent from QLD to NSW DPI molecular group to use with their LAMP kit.

Over the past six months, the project team have reported progress on the following:

• Continued surveys of grower properties are finding increased hosts for both Serpentine Leafminer (SLM) and the American Serpentine Leafminer (ASLM) in the regions they are currently found.
  
  
• Specimens of both SLM and ASLM are continually being sent to both NSW DPI molecular group and Cesar Australia for identification and testing using the LAMP primers developed for this project and using the qPCR assays developed by Cesar Australia, which work effectively in the laboratory on flies, larvae and empty mines excised from leaves and in the field on flies and larvae. In total, 61 samples have been received and processed, the majority from QLD.
  
  
• DNA barcoding of sampled Agromyzid leaf miner species for comparative species identifications of sampled Agromyzids is ongoing, with samples being received from both NSW and QDAF researchers with an additional 90 samples sent for identification and barcoding.
• DNA has been isolated from 256 specimens to date. This will be used to aid in the identification of specimens against a diverse library of DNA sequences reported at public repositories.
  
  
• A rapid and simple DNA extraction method, suitable for LAMP analyses was identified by NSW DPI molecular diagnostics project team, and planned validation testing will determine reliability of the approach for infield testing.
  
  
• Cesar Australia have been working on improving processing of empty leaf mines excised from leaves in the field. To process excised leaf mines in the laboratory they currently use a modified chelex extraction protocol, which is sensitive to low DNA concentrations. They are now exploring how they can convert the Chelex method to a field protocol. 
• Cesar Australia have received and tested samples of empty leaf mines from celery collected from local supermarkets in Victoria, which were identified as SLM, highlighting the effectiveness of the assay for Liriomyza huidobrensis on empty leaf mines.
  
  
• Empty leaf mine samples from Cape York Peninsular have been identified as American serpentine leafminer, as have samples received from the Northern Territory and Western Australia. This highlights the effectiveness of the multispecies assay which detects trifolii, and also confirms the specificity of the Liriomyza huidobrensis assay.

In terms of stakeholder engagement, the following has occurred:

• AUSVEG Project Lead Zarmeen Hassan presented at the national Potato Conference held in Victoria. Questions predominantly related to containment and chemical reactions.
  
  
• With the recent confirmed sightings of SLM in Victoria, a document has been produced by Cesar Australia in collaboration with QDAF and AUSVEG outlining the process for growers to send in samples for identification. This was circulated by the two VegNET Regional Development Officers in Victoria as well as the Weekly Update produced by AUSVEG.
  
  
• A successful annual agronomist breakfast was held 23 August in Bundaberg facilitated by RDO Andrew Halpin.
  
  
• A webinar for a group of Victorian agronomists was held 8 September in collaboration with the two Victorian RDO’s Danielle Park and Bonnie Dawson.
  
  
• Workshops/information sessions were held in the Northern Territory in Darwin and in Western Australia at Kununurra, with the audiences predominantly made up of agronomists and researchers with a few growers at both events. Northern Territory RDO Mariah Maughan facilitated the Kununurra workshop and arranged a one-on-one grower visit in Katherine.  
  
  
• Lockyer Valley RDO Caley Croft collaborated with QDAF’s John Duff to bring agronomists together for an update and discussion on SLM that was held on the 20 sept 2022. This event was well attended with solid feedback and interaction between agronomists and presenters.
  
  
• AUSVEG Project Officer Cherry Emerick organised a road trip from Bowen to Mareeba with AUSVEG Project Lead Zarmeen Hassan and QDAF Project Leader John Duff. The team disseminated information to the local DAF Bowen research station team members, and conducted one on one grower visits in Bowen, Gumlu, Home Hill, Ayr and Mareeba.  
  
  
• AUSVEG Project Officer Cherry Emerick also visited four growers while in the Bundaberg region, presenting to their onsite agronomists and farm managers.
  
  
• Department of Tourism Industry and Trade (DITT) Officers arranged two grower visits in the NT where the team sighted ASLM at both farms. The depth of infestation was highly visible at one of the farms due to harsh chemicals being used. The project team also visited a local nursery where ASLM has also been present. RDO Caley Croft organised two visits with Vietnamese growers involved in protective cropping, discussing leafminers and on farm Biosecurity.
  
  
• AUSVEG Project Lead Zarmeen Hassan, Project Officer Cherry Emerick and Western Australia (WA) RDO Michael Bartholomew collaborated with the Department of Primary Industries and Regional Development (DPIRD) to organise farm/grower visits, market visits and a Field walk. They spoke with 20 growers and agronomists from Manjimup, Gingin, Carabooda, Neerabup, Myalup, Muchea, Lancelin, Mandagalup and Perth South.