American serpentine leafminer (Liriomyza trifolii) Kununurra

By July 23, 2021 No Comments

Situation Update
The invasive exotic pest, American serpentine leafminer (Liriomyza trifolii), has been detected in Kununurra. This is the first time this pest has been detected on mainland Australia. American serpentine leafminer is a small fly whose larvae feed internally on the leaves of plants, disrupting photosynthesis and reducing quality and yield. They are particularly a problem in protected cropping systems.

Plants can be affected during all growth stages. Unlike many other leafminers, the American serpentine leafminer is polyphagous – meaning it has a broad host range from a number of families. Important agricultural hosts include include beans, lettuce, celery, cucumber, onion, potato, tomato, faba beans, chickpeas, soybeans, lentils, peanuts, and a wide range of ornamental species such as chrysanthemum and gerbera.

The national technical committee, the Consultative Committee on Emergency Plant Pests, has concluded that eradication may not be technically feasible, due to the pest’s biology, current distribution and wide range of host plants, more surveillance and data is required to make a determination.

The committee agreed that there may be measures that could be undertaken to limit the spread of American serpentine leafminer to other areas of Australia. More information on the agreed course of action will be provided as soon as possible.

Next steps

The Department of Primary Industries and Regional Development (DPIRD) is working with industry stakeholders and State and Commonwealth Governments to minimise the impact of the pest fly and its larvae on WA’s primary industries.

Delimiting surveys in American serpentine leafminer host crops in Kununurra, Broome, Carnarvon and Geraldton to determine the spread of the pest are currently underway.

Any adult specimens found will be confirmed by DPIRD laboratories. DPIRD laboratories are also examining samples gathered from Kununurra properties as part of associated surveillance activities. No properties are likely to be quarantined as part of the response.

Treatment Options
Permits are in place for leafminer fly species that include American serpentine leafminer, with more information available from the Australian Pesticides and Veterinary Medicines Authority website.

The insect is known to develop resistance to insecticide treatments so applications should be carefully considered. Overseas, management of leafminers, including the American serpentine leafminer relies on natural enemies, such as parasitoids that attack the larvae.

Actions to minimise risk Growers and gardeners are encouraged to do the following:

  • Monitor plants and report any suspect leaf damage to the department. Look for trails or ‘mines’ – light green to white squiggles – on leaf surfaces.
  • Practice good on-farm biosecurity. Localised spread of the pest is most likely to occur on contaminated plant material or equipment.

Biosecurity and reporting Report biosecurity concerns and suspect leaf damage to DPIRD’s Pest and Disease Information Service on (08) 9368 3080 or email padis@dpird.wa.gov.au.

Alternatively, send photos via DPIRD’s MyPestGuide Reporter app. (Google Play Store and Apple iTunes Store), or email padis@dpird.wa.gov.au

Further information

For further information please visit agric.wa.gov.au/American-serpentine-leafminer or contact Incident Controller, David Cousins on david.cousins@dpird.wa.gov.au or (08) 9368 3920.


DPIRD Industry Update
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Presentation on American serpentine leafminer. Includes information about lifecycle, international host list, market access implications.
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