The Department of Primary Industries and Regional Development's (DPIRD) surveillance program for red imported fire ant (RIFA) at Fremantle Port and surrounds is progressing well, identifying another queen and two worker ants.
The queen, buried half a metre underground at the initial nest site, and the nearby worker ants were discovered after odour detector dogs Willow and Cola, from the National Red Imported Fire Ant Eradication Program (NRIFAEP) in South East Queensland, indicated the ant activity.
RIFA (Solenopsis invicta) are characterised by their ability to form 'super colonies' with multiple queens and is one of the world's worst invasive ant pests.
While no further nests have been detected, the dogs and their handler detected another invasive species, browsing ants (Lepisiota frauenfeldi), within the port facility.
DPIRD chief plant biosecurity officer Sonya Broughton said a single browsing ant nest had been found.
Dr Broughton said browsing ants had been found in Western Australia before.
"WA successfully eradicated browsing ants from Perth airport in 2016 and Belmont in 2017 and is on track for eradication at Welshpool and Kewdale," Dr Broughton said.
"Ongoing surveillance is undertaken throughout WA as part of a national browsing ant response.
"The RIFA detection was actually made as part of the browsing ant surveillance activities."
Unlike RIFA, browsing ants do not pose a threat to human and pet health, although they do have a significant impact on the environment, invertebrate diversity and social amenity.
Hailing from southern Europe, browsing ants 'farm' other pests, like aphids, mealy bugs and scale insects, which can damage horticulture crops and gardens.
Fremantle residents, businesses and port workers are urged to remain vigilant and continue to report any sightings of unfamiliar ants.
"RIFA look very similar to common native ants, are reddish brown in colour with a darker abdomen and vary in size between two to six millimetres long," Dr Broughton said.
"Browsing ants are generally smaller, three to four millimetres long, with slender, shiny and dark brown bodies and run about in a haphazard manner when disturbed.
"Please be careful when observing and reporting any ants and take preventative measures to ensure you do not come into contact with the pest, which could be RIFA and may inflict a fiery sting."
Suspect ant sightings should be reported to the department using its MyPestGuideTM Reporter app or online at mypestguide.agric.wa.gov.au.
Alternatively, contact the Pest and Disease Information Service on +61 (0)8 9368 3080 or firstname.lastname@example.org
Fremantle residents and businesses are reminded that a Quarantine Area Notice to prevent the spread of the exotic ants is in place from Port Beach, as far south as the South Fremantle Dog Beach and east to East Street.
The notice restricts the movement of a range of host materials in and out of the area, including soil, potted plants, mulch, hay, manure and turf, as well as machinery or equipment used in digging or earthmoving.
For more details about the Quarantine Area Notice and information on RIFA and browsing ants and the DPIRD's response visit agric.wa.gov.au.