Importation of red imported fire ants into NSW - key threatening process listing

NSW Scientific Committee - final determination

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the Importation of Red Imported Fire Ants Solenopsis invicta Buren 1972 into NSW as a KEY THREATENING PROCESS in Schedule 3 of the Act. Listing of a key threatening process is provided for by Part 2 of the Act.

The Scientific Committee has found that:

1. The Red Imported Fire Ant Solenopsis invicta is a small colonial ant that is a native of the Pantanal region of southern Brazil in South America. The worker caste of the fire ant has a reddish brown head and body and a darker abdomen. Two sizes of workers are present in a colony with the majors being 6-7 mm in length and the minors about 2-5 mm long. Other features of this species are the aggression of fire ant workers and their painful sting.

2. Red Imported Fire Ant colonies can contain a single queen (monogyne) or multiple queens (polygyne) with between 200,000 and 400,000 workers. Monogyne colonies vigorously defend territory around the colony and achieve a density of up to 680 mounds per hectare whereas polygyne colonies allow workers to move between colonies allowing mound densities of up to 2,600 per hectare. New colonies are formed by flights of winged ants leaving the colonies.

3. Foraging Red Imported Fire Ants collect both liquid (usually oils and carbohydrates) and solid foods such as seeds. They damage plants by eating fruit, seeds, tunnelling into stems and girdling seedlings. They also prey heavily on ground invertebrates and attack any slow moving vertebrates such as bird nestlings. People, stock and domestic pets are readily stung if they disturb a nest and this can induce anaphylactic shock in sensitive individuals (Vinson 1997).

4. Red Imported Fire Ants have been transported to North America where they have become an aggressive, invasive species over much of the southern United States and parts of California. Red Imported Fire Ants have recently been discovered at two separate foci in Brisbane, Queensland. The monogyne form occurs at the Fishermans Island container wharf in Moreton Bay. The polygyne form has been found over a large area of the south-western suburbs of Brisbane centred on Wacol.

5. Preliminary studies on the impact of the Red Imported Fire Ant on biodiversity in Brisbane have found that bushland with fire ant colonies present have greatly reduced numbers of native cockroaches and terrestrial reptiles. Frogs and ground nesting birds are also affected (Natrass & Vanderwoude 2001). Studies in North America have found that Red Imported Fire Ants largely replace the native invertebrate predatory species, becoming the dominant predator and disrupting invertebrate food webs (Jetter et al. 2002). There is the potential for Red Imported Fire Ants to impact on ecological communities by affecting pollination and seed dispersal.

6. Species and populations in NSW that may become threatened by the presence of Red Imported Fire Ants include ants such as Rhytidoponera spp., Pheidole spp., Paratrechina spp., Eastern Sedgefrog Litoria fallax, Eastern Grass Skink Lampropholis delicata, and a burrowing skink Ophioscincus truncates (Natrass & Vanderwoude 2001). A range of other ground-dwelling invertebrates and vertebrates would be affected in NSW.

7. A major control program has been initiated by the Queensland government to try and eradicate the Red Imported Fire Ants over the next five years. The program seeks to contain the spread of the ant and to poison the existing colonies using a bait with a poison that targets the queen in a colony. The principal means of transport of queens is in soil and landscaping products such as mulch, old timber rails and pot plants. The Queensland Department of Primary Industry has declared a Pest Quarantine Area around Brisbane to prevent the movement of materials from infested locations and NSW Agriculture has declared the Red Imported Fire Ant a notifiable pest requiring reporting if discovered in NSW. There is a substantial trade of nursery plants from south-eastern Queensland into NSW, SA and Victoria.

8. Climatic modelling of the potential habitat for the Red Imported Fire Ants across Australia shows that they could occupy most of the coastal belt and the more mesic inland areas (Sutherst 2001). This includes the eastern half of NSW except for the Alpine region. Workers forage during the warmer months of the year when temperatures are between 22oC and 36oC.

9. In view of the above the Scientific Committee is of the opinion that the Importation of Red Imported Fire Ants Solenopsis invicta Buren 1972 into NSW is eligible to be listed as a Key Threatening Process because it could cause species, populations or ecological communities that are not threatened to become threatened.

Proposed Gazettal date: 23/08/02

Exhibition period: 23/08/02 - 27/09/02

 

References

Jetter K.M., Hamilton J. & Klotz J.H. (2002) Red imported fire ants threaten agriculture, wildlife and homes. California Agriculture 56: 26-34.

Natrass R. & Vanderwoude C. (2001) A preliminary investigation of RIFA in Brisbane. Ecological Management & Restoration. 2: 220-223.

Sutherst, R.W. (2001) Red Imported Fire Ant Solenopsis invicta: CLIMEX Species Report. Unpublished report to Qld Dept of Primary Industry: Brisbane

Vinson, S. B. (1997) Invasion of the Red Imported Fire Ant (Hymenoptera:Formicidae). Spread, biology and impact. American Entomologist. Spring 1997:23-39.

 

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Page last updated: 28 February 2011