January 2020 Pest of the Month: Vegetable leafminer

Thursday, 9 January 2020

Name: Vegetable leafminer, Liriomyza sativae

Vegetable leaf miner (Liriomyza sativae) is a fly that has a wide host range and can cause significant damage, reduce crop yield and marketability of many common horticultural crops and ornamental plant species.  It is present in north Queensland and is likely to spread.

Some economically important weed and cultivated crop hosts include squash, okra, pea, tomato, bean, cabbage, turnip, potato, tobacco, cotton, radish, spinach, watermelon, beet, pepper, alfalfa, clover, vetch and plantain.

Similar to: Other leaf mining flies

Description:

The vegetable leafminer lifecycle varies with host and temperature, at 25oC to 30oC a lifecycle takes approximately 15 days, while at 15oC the lifecycle takes up to 25 days. Adults can survive temperatures down to 12oC but appears to stop feeding and laying eggs. Pupa can survive freezing temperatures but die before emergence at temperatures above 32oC. Ten or more generations can be produced in a year.

Eggs: microscopic (0.24 mm long), oval and creamy white, laid inside the leaf and hatch within 2 to 7 days.

Larva: have three instar (larval) stages, are a legless maggot about 2.5 mm long with black mouth parts. The larva change from colourless to greenish to yellowish as they grow. When mature they cut a slit in the leaf and drop to the ground to pupate.

Pupa: oval, segmented and slightly flattened, reddish brown and about 1.5 mm in length. Adults emerge after approximately 9 days.

Adults: are small, inconspicuous, greyish-black insects. They have a yellow and black body, 1.3-2.3mm in length. Adults can mate 24 hours after emergence and live for 15 to 30 days depending on conditions. They are not very active flyers and may be seen walking rapidly with short flights to adjacent leaves. The best way to recognise vegetable leafminer is through the damage they cause.

Damage:

Damage is caused by larvae feeding under the surface of leaves and petioles. Typically, this feeding causes long, narrow ‘mines’ which appear as white or grey lines on leaves (and can also look like coils) widening towards the end. Multiple mines on an individual leaf greatly reduces the photosynthetic ability of the plant. Damage caused by vegetable leaf miners considerably reduces the growth and development of seedlings and young plants, and can lead to plant death.

For more information, head to: https://www.pestid.com.au/pest-insect/vegetable-leaf-miner-2

Note that the Pest ID tool is now available with free access to industry

An initiative of the Nursery Levy funded National Nursery Industry Biosecurity Program (NY15004) and ‘Building the resilience and on-farm biosecurity capacity of the Australian production nursery industry’ Project (NY15002).