Serpentine leafminer (SLM, Liriomyza huidobrensis), has been declared a List A Regulated Quarantine Pest of concern to Tasmania following the discovery of an outbreak of the pest in New South Wales and Queensland.
This declaration follows a rapid risk assessment, conducted by Biosecurity Tasmania (BT) that determined SLM is likely to have capacity to establish and spread in Tasmania.
Leafminer damage on leaf. Photo: Bugwood.org
Adult Serpentine leafminer. Photo: Bugwood.org
Minimising the risks
For Tasmania, practical and effective border restrictions for this pest are not available and the potential for effective inspection of imported host produce to mitigate entry is limited. As a result, industry awareness of this pest is important, as is the focus on effective management, such as employing Integrated Pest Management approaches used for leaf miner pests already present in Tasmania.
For further information see: Management of leafmining flies in vegetable and nursery crops in Australia (PDF)
SLM has a very wide host range that includes many crop species (particularly leafy greens and vegetables) ornamentals and weeds that are present in Tasmania. Well known hosts include beans, beet, broccoli, cut flowers, onions, peas, potatoes and spinach.
The lifecycle of SLM is typical for many leaf mining flies. Female flies puncture the leaves of the host plants causing wounds which serve as sites for feeding or oviposition. Eggs are inserted just below leaf surface. Three larval stages feed within the leaves predominantly feeding on the plant in which eggs are laid and creating thick white trails called 'leaf mines'. Larvae leave the plant to pupate in crop debris, litter or soil.
Signs of SLM include feeding punctures and irregular leaf mines. In some cases, heavy infestations can lead to necrosis and plant death.
Surveillance and diagnosis
BT is undertaking SLM surveillance as part of this season’s plant pest surveillance activities and BT entomology staff are in the process of enhancing diagnostic capacity for this pest.
Surveillance will consist of setting traps near susceptible host plants by participating members of the public and growers. Visit the Adopt-a-trap pest survey webpage for details on how to participate in this program.
To supplement surveillance, growers and members of the public are invited to submit plant material suspected to be infested with SLM. BT will identify suspected SLM specimens at no cost.
The identification of infested leaf material will be complicated as similar leafminers are very common in Tasmania and an accurate diagnosis can only be made by rearing larvae through to the adult stage or molecular testing.
Common leafminers in Tasmania include Liriomyza chenopodii (beet leafminer), Liriomyza brassicae (cabbage leafminer), Chromatomyia syngenesiae (cineraria leafminer) and Scaptomyza flava (turnip leafminer).
Due to the presence of these common leafminers in Tasmania, submission of leaf samples for suspected SLM should be prioritised to the following:
- Heavy leafminer infestations on commercially grown plants, particularly if the infested plants have not been infested previously.
- Plants that are not commonly infested with the common Tasmanian leafminer species including
- Bellis perennis (lawn daisy)
- Calendula (pot marigold)
- Tagetes (marigold)
Sample collection and submission
Biosecurity Tasmania will identify suspected SLM specimens at no cost.
- Collect small leaves or parts of large leaves that have obvious, recent leafminer tunnels in them.
- If you find small brown pupae (1-2 mm long) on the underside of leaves collect these as well.
- Place the samples in a zip lock sandwich bag. Press the air out and securely zip the lock fully closed.
- Write on the front of the bag in permanent black marker the name of the host plant, date and location address collected and the name of the person who collected it.
- Collect each host plant in a different zip lock bag.
- Place all of the sample bags inside one larger zip lock bag (to ensure all insects are contained) and place inside a padded envelope with a completed sample submission form:
Plant Diagnostic Services - Sample Submission Form (454Kb)
- Post or deliver to the nearest Biosecurity Tasmania entomology laboratory:
- South: New Town Laboratories, 13 St Johns Avenue, New Town 7008
- North: Mt Pleasant Laboratories, 165 Westbury Road, Prospect 7250
- North-West: Stony Rise Government Offices, Rundle Road, Devonport 7310