The vegetable leaf miner (Liriomyza sativae) is continuing its march across the globe and was recently detected on mainland Australia for the first time, having been island hopping across Torres Strait since about 2008.
Vegetable leafminer was first detected by biosecurity officers working for the Northern Australian Quarantine Strategy as part of the annual plant health surveys throughout Northern Australia and Torres Strait.
In 2014 the Consultative Committee on Emergency Plant Pests agreed that it is not technically feasible to eradicate vegetable leafminer from the Torres Strait islands.
On 1 May 2015, routine surveillance detected two vegetable leafminer larvae in the Cape York Peninsula community of Seisia. They were found in a backyard garden on siratro which is a widespread legume plant, commonly used as a pasture.
Seisia is located within the Cape York Peninsula Pest Targeted Quarantine Area: no plant materials can be moved out of the area without approval.
Surveillance also found mines in leaves similar to those of vegetable leafminer on pumpkin and tomato plants, located 30 kilometres from Seisia on Albany Island. However, no adults or larvae were found.
Vegetable leafminer affects a broad range of vegetables and ornamentals, including a native plant that grows on the Cape York Peninsula, and numerous weed species. The pest is wind borne and eggs, larvae and pupae can be moved through plant material, soil, clothing and equipment.
Vegetable leafminer damage is primarily caused by larvae feeding under the surface of leaves and petioles. This feeding causes long, narrow ‘mines’ which appear as white or grey lines on leaves. Higher levels of infestation affect the plant’s ability to photosynthesise, reducing plant growth and crop yields.
Foliage punctures caused by females during feeding may cause a stippled appearance on leaves and stems, however this damage is small compared to the leaf mining activity of the larvae.
L. sativae is extremely fertile and can have as many as 300 to 400 offspring per female. Mature larvae leave the mines, dropping to the ground to pupate. The life cycle takes only two weeks in warm weather.
The diet of vegetable leaf miner includes cucurbits (cucumber, bitter-gourd, zucchini, squash and pumpkin), solanaceae (eggplant, capsicum, potatoes, and tomatoes) and leguminosae (red kidney beans, soybeans, lima beans, cannellini beans, chickpeas, lentils and split peas).
However, affected hosts are not restricted to vegetables, as the pest also affects ornamental plants and most allium species, including onions and garlic.
Vegetable, grain and flower growers are encouraged to adopt good biosecurity practices to prevent pest and disease incursions. You should also regularly check crops for signs of disease and pest activity.
It is important to be aware of the major pests, diseases and weeds in your region, as well as those that are exotic to your property. Keep a list of pests and diseases and ensure that farm staff are aware of what symptoms to look out for while inspecting crops.
If you suspect you might have a vegetable leafminer infestation, report it to the department of primary industries or agriculture in your state or territory by calling the Exotic Plant Pest Hotline on 1800 084 881.
Acknowledgement: Information in this article is reproduced from material by AUSVEG and the Department of Agriculture