THE invasive exotic pest American Serpentine Leafminer (ASLM) has been found in northern Western Australia, causing concern among farmers and relevant industry associations.

ASLM is a tiny fly whose larvae damage plants by boring through leaf tissue.

Leaf damage occurs through puncture wounds from the adult eggs that feed and lay eggs, as well as through the larval tunnel or mine within the leaf tissue.

The Department of Primary Industries and Regional Development (DPIRD) confirmed the presence of the pest in WA based on a sample taken last Thursday as part of the Commonwealth’s Quarantine Strategy Monitoring Program near Kununurra.

DPIRD works with industry stakeholders and state and Commonwealth governments to minimize the impact of the pest fly and its larvae on WA’s primary industries.

The plant pest is carried by the wind, and eggs, larvae and pupae can be spread through the movement of plant material, soil, clothing and equipment.

Sonya Broughton, DPIRD’s chief plant biosecurity officer, said the department is conducting surveys in the Kununurra, Broome, Carnarvon and Geraldton area.

“This is the first time this species of leaf miner has been found in mainland Australia,” said Ms. Broughton.

“The American snake leaf miner, so called because the larval tunnel forms snake-like mines in the leaves, is known to feed on more than 400 species from 29 plant families, including most vegetables, pulses and ornamental plants.

“We work with growers as we survey production areas in the northern half of the state to determine the presence and spread of the pest.”

Grain Producers Australia (GPA) vice chairman and national biosecurity spokesman Barry Large said grain producers need to be vigilant of the pest’s recent discovery and be proactive in monitoring their farms.

“State and federal biosecurity agencies continue to conduct surveillance and traceability activities to determine the full spread of the pest – and grain farmers should also be on the lookout for possible intrusions into their legumes,” said Mr. Large.

“Although the threat to the grain industry and crops from this tropical incursion may be limited at this early stage, grain producers must be aware of the potential risks and take the necessary preventive measures.

“Farmers are encouraged to regularly check and monitor their crops for signs of this crop pest, which is believed to be a serious economic threat to our national crop industries.”

The national technical committee, the Emergency Plant Pests Advisory Committee, has concluded that while the pest’s biology, current distribution and wide range of host plants make eradication technically impossible, more monitoring and data are needed to to make a decision.

The committee agreed that measures could possibly be taken to limit the spread of ASLM to other areas of Australia.

More detailed information on the agreed procedure will be announced as soon as possible.

“The insect is known to develop resistance, so insecticide treatments that incorporate resistance management strategies should be used to minimize this risk,” said Ms. Broughton.

“Overseas, management of leaf miners, such as the American serpentine leaf miner, involves the use of natural predators, such as parasitoids, that attack larvae, so good management practices should consider the use of pesticides that favor beneficial insects.”

Breeders and gardeners are encouraged to monitor plants and report any tunnel leaf damage and suspicious flies to the department to verify the absence and presence of the pest.

“Adult American serpentine leaf miners are one to two millimeters tall, gray-black, and have a distinctive yellow area at the base of the wings,” said Ms. Broughton.

“Damage by the pest can be identified by twisted white patterns on the leaf surface caused by the tunnel activity within the leaf of the white-yellow larvae, but this is indistinguishable from other leaf-shedding flies.

“This tunneling can hinder the photosynthesis of the plants, which leads to leaf death or premature leaf fall, which leads to yield losses, sunburn and reduced quality.”

ASLM is widespread overseas and has a presence in the Americas, Asia, Africa, Europe and some Pacific islands.