Fact sheet

Exotic Leaf Miners spp.

Exotic polyphagous leaf mining of the genus Liriomyza are pests that pose a serious threat to Australian agricultural and horticultural industries. There are many Liriomyza species already present in Australia, including some that are native but not all impact on horticultural production. Leaf miners feed in tunnels under the leaf surface — these tunnels cause visible damage which is referred to as ‘mines’. Distribution There are more than 300 species of Liriomyza worldwide, with only five exotic species considered significant pests that are known to attack a wide variety of plants: • (Serpentine leaf miner) — confirmed detections on field grown vegetables in Western Sydney in New South Wales and Kalbar in the Fassifern Valley region of Queensland in 2020 • Liriomyza sativae (Vegetable leaf miner) — detected Cape York Peninsula, Queensland in 2015, and under official control • Liriomyza bryoniae (Tomato leaf miner) — not present in Australia • Liriomyza cicerina (Chickpea leaf miner) — not present in Australia • (American Serpentine leaf miner) — not present in Australia.

Description The adult flies of Liriomyza species, including exotic and local species present in Australia look very similar. Reliable identification requires examination under a microscope. They are small (1 to 3mm) grey-black flies with yellow markings. The larvae of Liriomyza leaf miners are yellow to white in colour and feed in the living plant tissue in tunnels beneath the surface of the plant. Larval mining tunnels can be seen on the leaves of infested plants.

Adult leaf miner; captured by Dr. Elia Pirtle (cesar Pty. Ltd.)

Life Cycle Several generations can be produced during a year. Female flies pierce the leaf surface to lay eggs inside leaf. 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 on the leaf surface or in the soil. The entire life cycle can be as short as two weeks.

Damage Exotic leaf miners leave squiggly white lines on impacted host plants. Heavy tunnelling damage reduces the ability of the plant to photosynthesise which can result in leaf death or premature leaf drop. Heavy infestations can leave stippling damage on plants from the feeding and egg laying sites of the adult females. Mine damage can also Damage caused by vegetable leaf miner; reduce crop yield and leave leafy green crops Dr. Elia Pirtle (cesar Pty. Ltd.) unmarketable due to the tunnelling left behind. Hosts Exotic leaf miners have a very wide host range, including common weeds in the Asteraceae (sow thistle) and Solanaceae (nightshade) and Fabaceae families. Common vegetable crop hosts include:

• beans • celery • lettuce • peas • • cucumber • nursery plants • potatoes • capsicum/chili • eggplant • onions • tomatoes. Spread Leaf miners are spread through the movement of live host plants containing eggs, larvae, or adults, as well as the movement of pupae via contaminated soil or potting media. Adult leaf miners are typically poor fliers, usually moving only short distances between crops, but are also capable of travelling long distances by hitchhiking via human movements or through wind dispersal. Recognising exotic leaf miners Leaf miner damage caused by local leaf miner species is generally not distinguishable from damage caused by exotic leaf miners. Therefore, any suspect leaf miner damage should be reported. If you suspect an exotic leaf miner infestation, you should report it immediately to the Exotic Plant Pest Hotline on 1800 084 881. Reporting suspected cases Quick reporting can prevent a major outbreak. If you detect a disease or pest, report it by calling the Exotic Plant Pest Hotline on 1800 084 881. Alternatively, you can make a report by submitting the online plant pest report form.

Disclaimer: The material in this publication was prepared from the most up-to-date information available at the time of publication. It is intended as a guide only and the publisher accepts no responsibility.

February 2021