The Department of Agriculture, Western Australia is stepping up its quarantine efforts following confirmation of lettuce aphid (Nasonovia ribisnigri) in Victoria.

Western Australia has extended its plant quarantine measures for importation of host plants and host plant material of lettuce aphid from all States except Queensland.

Manager Plant Health Dr Shashi Sharma, said Australia had been free of this serious pest until it was reported in Tasmania in March 2004. Lettuce aphid is a major pest of lettuce and other crops.

Although it does not severely damage lettuce plants, its presence renders lettuce heads unsaleable. Lettuce aphid is also known to transmit plant diseases. 

The lettuce aphid is also called the currant-lettuce aphid because in addition to lettuce, another significant host is Ribes species (gooseberry, and red, black and white currants). 

Other hosts include many species from the plant family Asteraceae such as chicory, nipplewort (Lampana) and hawkweed (Crepis).  Hieracium, speedwell (Veronica), tobacco and petunia are also known hosts of lettuce aphid.

Lettuce aphids prefer to feed on new leaves deep inside the plant. Aphids feeding deep in the plant may be orange or red; those feeding on outer leaves may be green.

In response to its initial detection in Tasmania and its eventual spread to mainland Australia, and to minimise the risk of the pest being imported into Western Australia, a Pest Risk Analysis (PRA) was undertaken by the Department of Agriculture Western Australia.

The PRA underpinned plant quarantine measures for the entry into Western Australia of lettuce aphid host plants and host plant material from other Australian States and Territories.

The measures are designed to facilitate safe trade and protect Western Australia from importation of the pest and preserve the State’s Area Freedom from lettuce aphid.

The Western Australian Quarantine and Inspection Service (WAQIS) will immediately implement the measures for lettuce aphid in respect of imports from other states.

Although it has now been acknowledged that lettuce aphid has spread to mainland Australia, Dr Sharma said Western Australia would consider claims from other States for Area Freedom if they undertook adequate surveys for the pest.

The property in east Melbourne where several stages of lettuce aphid were detected is isolated from other lettuce or vegetable production sites and is located about 30 km from the nearest production areas at Keilor, Werribee and Cranbourne. 

The pest was also detected in parklands at Scoresby and Eltham on the host Hawkesbeard weed (Crepis capillaris).

As part of a National Strategy, the Department of Agriculture conducts surveillance for lettuce aphid in order to maintain the State’s freedom from lettuce aphid.

The ‘Final State Pest Risk Analysis, Lettuce Aphid into Western Australia’ can be seen online at www.agric.wa.gov.au.

General information and photographs can be found at www.aphidwatch.com and http://ccvipmp.ucdavis.edu/insects/lettuceaphid.html. 

Anyone who suspects they have found lettuce aphid is requested to call the Exotic Plant Pest Hotline on 1 800 084 881.