Serpentine leafminer

Alert

Serpentine leafminer (Liriomyza huidobrensis) has been detected for the first time in Queensland following a confirmed report of the pest in Western Sydney in November 2020.

If you suspect you have found serpentine leafminer or vegetable leafminer in Queensland, report it to the Department of Agriculture and Fisheries (DAF) on 13 25 23.

Serpentine leafminer (Liriomyza huidobrensis) is a small fly whose larvae feed internally on plant tissue, particularly the leaf, causing distinctive mine damage.

It poses a significant threat to Australia's agriculture and nursery industry as it is a highly polyphagous species affecting a wide host range of common horticultural crops and ornamental plant species.

Infestation of plants would most likely be detected through the presence of mines in the surface of leaf tissue. Leaf mines usually appear white or pale green with black and dried brown areas. Leaf mines are typically serpentine or irregular in shape and increase in size as the larvae mature.

Cause

Serpentine leafminer (Liriomyza huidobrensis) are small flies belonging to the family Agromyzidae.

The damage is caused when fly larvae tunnel within leaf tissue, which is why they are called leafminers.

Other names

  • Liriomyza huidobrensis
  • pea leafminer
  • South American leafminer
  • Liriomyza

Description

Adults

  • Small fly, 1–2.5mm.
  • Black with yellow head and yellow spots on thorax.
  • Brownish-yellow antennae with dark end segments.

Larvae

  • Transparent when they first hatch before turning pale yellow-orange then solid yellow-orange as they mature.
  • Develop inside leaf tissue and vary in size but can reach up to 3.2mm.
  • Form irregular serpentine mines, which tend to be restricted by veins.

Pupae

  • Pupation occurs externally to the leaf usually in the soil below the plant and sometimes on the leaf surface.
  • Adversely affected by high humidity or drought.

Eggs

  • Slightly translucent and off-white.
  • Tiny, barely visible to the naked eye.
  • Laid under the leaf surface.

Plant stage and plant parts affected

Host plants of any age and stage of growth can be infested but young plants are most susceptible. Serpentine leafminer mainly affects leaf tissue.

Plant damage

Mines in the surface of leaf tissue are typically the first signs. Leaf mines are usually white or pale green, with black and dried brown areas. Leaf mines are typically serpentine or irregular in shape and increase as the larvae mature.

Mining activity by the larvae causes loss of healthy leaf tissue, affecting the plants ability to photosynthesize. The damage caused when the fly lays its eggs, or during the mining process of the larvae, can lead to diseases caused by fungi and bacteria. In severe infestations leaves can wilt and die, causing defoliation.

May be confused with

Similar damage could be caused by other leaf mining insects that are present in Queensland.

Serpentine leafminer and vegetable leafminer produce highly convoluted (squiggly) leaf mines and have a broad host range. If you find leafminer damage on a variety of plant species, you should report it to the Department of Agriculture and Fisheries.

Distribution

The serpentine leafminer originated in the highlands of South America and is better adapted to cooler climates than the vegetable leafminer.

It is established in Africa, Asia, Central America, Europe and North America (in glasshouses in Canada, but not in the United States) and in Indonesia and West Timor.

Serpentine leafminer was first detected in New South Wales and Queensland in November 2020.

Hosts

Serpentine leafminer affects a wide host range of common horticultural crops and ornamental plant species.

They have been found to seriously affect solanaceous crops (such as potato, tomato and eggplant), as well as crops in the Asteraceae, Cucurbitaceae and Fabaceae families.

Life cycle

Several generations may be produced during a year. Female flies pierce the leaf surface to lay eggs inside. Eggs hatch in 2–5 days depending on temperature and larvae mine the leaf tissue. The larvae of serpentine leafminer primarily feed on the leaf in which the eggs were laid. Larvae leave the plant to pupate.

Impacts

Serpentine leafminer damage reduces crop marketability and yield, resulting in economic losses to growers, particularly for leafy vegetables.

How it is spread

The greatest risk of pest spread is by people moving infested plant material, soil or packaging.

Adult flies may also hitchhike in vehicles, machinery or aircraft.

The adult flies are not very strong flyers. The flies usually walk quickly over leaves and fly short distances to move between leaves or nearby plants. Strong winds may assist adult flies to fly further afield.

Monitoring and action

Inspect your plants regularly for the presence of leaf mines.

Look for leafminer damage on a variety of plant species or unusual or severe leafminer leaf damage.

If you suspect serpentine leafminer, report it to the Department of Agriculture and Fisheries.

Control

Growers should have on-farm biosecurity measures to protect their crops from pests and diseases. More information is available at farmbiosecurity.com.au or biosecurity.qld.gov.au.

Integrated pest management options are likely to be more effective than chemical suppression in the control of serpentine leafminer.

Find information about control methods and chemical management options for leafminers.

Further information