Preventative measures: The Pacific Ant Prevention Programme is a proposal prepared for the Pacific Plant Protection Organisation and Regional Technical Meeting for Plant Protection. The plan aims to prevent the red imported fire ant and other invasive ant species with economic, environmental or social impacts from establishing within, or spreading between, countries in the Pacific.
Please see Linepithema humile information sheet, prepared as part of 'The invasive ant risk assessment project', Harris et al. 2005., for Biosecurity New Zealand by Landcare Research.
Hartley et al. (2006) modelled the potential future range of the Argentine ant. They found that it is most likely to occur where the mean daily temperature in mid-winter is 7-14°C and maximum daily temperatures during the hottest month average 19-30°C. Uninvaded regions considered vulnerable to future establishment include: southern China, Taiwan, Zimbabwe, central Madagascar, Morocco, high-elevation Ethiopia, Yemen and a number of oceanic islands.
Integrated management: The potential of invasive ants to reach high densities is greater in human-modified ecosystems; particularly in land intensely utilised for primary production. For example, L. humile reaches high densities in agricultural systems, such as citrus orchards, that host Homopteran honey-dew producing insects (Armbrecht and Ulloa-Chacón 2003; Holway et al. 2002a). Improved land management, including a reduction in monoculture and an increase in the efficiency of primary production, may help prevent ant population explosions, alleviate the problems caused by high densities of ants and reduce sources of ant infestation.
Please follow this link for more detailed information on the management of the Argentine ant Linepithema humile compiled by the ISSG.
Location Specific Management Information
Linepithema humile is a pest in New South Wales (SE coastal), South Australia (Murray-Darling basin), Tasmania, Victoria (Murray-Darling basin, SE coastal), Western Australia (SW coastal). The Argentine Ant is a declared pest in Australia and former government control measures undertaken have been largely abandoned.
A giant supercolony of Argentine ants has been found stretching across Melbourne, which could pose a serious threat to the city's biodiversity. The ants are genetically uniform, no longer fight and have formed a giant supercolony that extends at least 100 kilometres across the city. The ants can move freely between physically separate nests (Monash University, 2004).
DEH (2005) classifies at least six key tramp ant as species of national priority for their impact or potential impact on Australian biodiversity
(red imported fire ant (Solenopsis invicta - RIFA); yellow crazy ant (Anoplolepis gracilipes - YCA); big-headed ant (Pheidole megacephala - BHA); Argentine ant (Linepithema humile - AA); little fire ant (Wasmannia auropunctata - LFA) and the tropical fire ant (Solenopsis geminata - TFA). DEH (2005) reports that recent incursions by several tramp ant species (e.g., YCA into northern New South Wales, Brisbane, and Cairns, and the Argentine ant (AA) in Brisbane) have been followed by rapid responses to achieve eradication.
The Threat abatement plan to reduce the impacts of tramp ants on biodiversity in Australia and its territories establishes a national framework to guide and coordinate Australia’s response to tramp ants, identifying the research, management, and other actions necessary to ensure the long-term survival of native species and ecological communities affected by tramp ants. It identifies six national priority species as an initial, but flexible, list on which to focus attention. They are the red imported fire ant (Solenopsis invicta), tropical fire ant (S. geminata), little fire ant (Wasmannia auropunctata), African big-headed ant (Pheidole megacephala), yellow crazy ant (Anoplolepis gracilipes), and Argentine ant Linepithema humile (Commonwealth of Australia. 2006a).
The Background document to the Threat abatement plan to reduce the impacts of tramp ants on biodiversity in Australia and its territories provides supporting information on a range of issues such as tramp ant biology, population dynamics, spread, biodiversity impacts and management measures (Commonwealth of Australia. 2006b).
Haleakala National Park
The most promising results have been obtained with the commercial product Maxforce Granular Ant Bait, a protein bait formulated with the toxicant hydramethylnon (Krushelnycky and Reimer 1998, in Krushelnycky et al. 2004). A study by Krushelnycky and colleagues (2004) that compared colony expansion of treated and untreated supercolonies found that the application of Maxforce prevented the border expansion of the treated colony. The boundary of the adjacent untreated colony advanced 65.2m within the same period. This is thought to be due to the reduction in ant densities. High ant densities at certain times of the year, stimulate colony expansion due to increased dispersal of the ants (Benois 1973, in Krushelnycky et al. 2004). While eradication has not been achieved in any test plots, Maxforce consistently reduces the number of foraging ants by over 90%. This reduction suppresses normal colony activities, including budding dispersal, for some period of time, has a low acute toxicity towards birds and mammals, is not taken up by plants, is practically insoluble in water and does not leach from soil (EPA 1998, Bacey 2000, in Krushelnycky et al. 2004). The greatest non-target effects from Maxforce treatment at Haleakala is likely to be on other arthropods. This risk was acceptable because of the highly detrimental effects of the Argentine ant on these same groups of arthropods, should they remain un-controlled.
Recent attempts have been made at eradication of Linepithema humile from Hawaii, using the toxicant hydramethylnon, but these have not been successful. The focus has now changed to strategies to suppress further invasion, which has met with moderate success (Krushelnycky et al. 2002). Eradication efforts ongoing at Haleakala National Park on Maui.
The aim of the Invasive ant pest risk assessment project (Harris et al. 2005) was to assess the threat to New Zealand from a wide range of ant species not already established in New Zealand and identify those worthy of more detailed assessment. A preliminary invasive ant risk assessment was conducted and a risk assessment scorecard was developed to quantify the threat to New Zealand of a range of ant species, and aid selection of those worthy of more detailed assessment. 75 taxa were scored and grouped into high, medium, or low threats. A summary was prepared for each taxa, outlining why it was considered for assessment, and the mitigating factors that affect its risk to New Zealand.
As part of the pest risk assessments, the threat each ant posed to New Zealand was considered in terms of: likelihood of entry; likelihood of establishment; likelihood of spread; and the detrimental consequences of its presence in New Zealand. The scores are compared with two species already established in New Zealand, Linepithema humile (a relatively widespread and abundant pest) and Pheidole megacephala (restricted in distribution and not currently considered a significant pest). Comparison was also made to Solenopsis invicta, which is widely recognized as a significant threat to New Zealand and other countries in Oceania and for which a risk assessment had already been conducted before this project.
Each pest risk assessment contains information under the following sections: pest information; likelihood of entry; likelihood of establishment; likelihood of spread after establishment; The environmental, human health and economic consequences of introduction; likelihood and consequences analysis.
Key points that have been drawn from the risk assessment by the authors are: "S. invicta has a similar score to Linepithema humile, which is already established in New Zealand and is a significant pest. Unlike S. invicta, L. humile does not have medical consequences associated with its presence, but S. invicta is likely to have a more restricted distribution and it is uncertain where it will establish and become abundant".
Please see Information sheet for more details of this species.
Please see TDC & Biosecurity NZ, 2005 for points to keep in mind when starting a control operation, notes on baits, examples of well-planned and executed baiting treatments which resulted in dramatic reductions in ant populations, and also examples of successful eradication on small sites at Mt Maunganui.
Tiritiri Matangi Is. (North Island)
If successful, the eradication of the Argentine ant on Tiritiri Matangi Island from approximately 11 hectares of land will be the largest site from which an invasive ant species has been eradicated from in New Zealand. In 2001 14 ant specialists from around New Zealand began treatment of the area with poison baits in the form of insecticide past baits (containing fipronil as the active ingredient). Post-bait monitoring revealed that 99% of ants were killed. Small infestations persist, particularly around the wharf shelter and near the wharf pond (Green 2001, C.Green Pers. Comm. 2003, in Hoffmann and O’Connor 2004; Green 2005).
For more information please see Control of Argentine ants on Tiritiri Matangi (N.Z.) offshore island sanctuary (Supporters of Tiritiri Newsletter #45).
1. AntWeb, 2006. Linepithema humile
Summary: AntWeb illustrates ant diversity by providing information and high quality color images of many of the approximately 10,000 known species of ants. AntWeb currently focusses on the species of the Nearctic and Malagasy biogeographic regions, and the ant genera of the world. Over time, the site is expected to grow to describe every species of ant known. AntWeb provides the following tools: Search tools, Regional Lists, In-depth information, Ant Image comparision tool PDF field guides maps on AntWeb and Google Earth and Ant genera of the world slide show.
AntWeb is available from: http://antweb.org/about.jsp [Accessed 20 April 2006]
The species page is available from: http://antweb.org/getComparison.do?rank=species&genus=linepithema&name=humile&project=&project= [Accessed 2 May 2006]
2. Commonwealth of Australia. 2006a. Threat abatement plan to reduce the impacts of tramp ants on biodiversity in Australia and its
territories, Department of the Environment and Heritage,
Summary: This plan establishes a national framework to guide and coordinate Australia’s response to tramp ants, identifying the research, management, and other actions necessary to ensure the long term survival of native species and ecological communities affected by tramp ants. It identifies
six national priority species as an initial, but
flexible, list on which to focus attention. They
are the red imported fi re ant (Solenopsis invicta),
tropical fire ant (S. geminata), little fire ant
(Wasmannia auropunctata), African big-headed
ant (Pheidole megacephala), yellow crazy ant
(Anoplolepis gracilipes), and Argentine ant
Available from: http://www.environment.gov.au/biodiversity/threatened/publications/tap/pubs/tramp-ants.pdf [Accessed 17 November 2009]
4. Department of the Environment and Heritage (DEH), 2005. Draft Threat Abatement Plan for for Reduction in Impacts of Tramp Ants on Biodiversity in Australia and its Territories
5. Forschler, B. T. and Evans, G. M. 1994. Argentine ant (Hymenoptera: Formicidae) foraging activity response to selected containerized baits. J. Entomol. Sci. 29(2): 209-214.
Summary: Found that baits formulated with hydramethylnon or sulfluramid were effective in eliminating foraging ants in an urban setting.
6. Green, C. 2005. Argentine ant update, Dawn Chorus 60: 8. Supporters of Tiritiri Matangi.
7. Haney, P. 1984. A different approach to the Argentine ant problem. Citrograph 69(6): 140-146.
Summary: Provides a brief review of historical chemical approaches to Argentine ant control in agriculture, and presents results for liquid Diazinon and Lorsban spray treatments of citrus trees.
9. Harris, R.; Abbott, K.; Barton, K.; Berry, J.; Don, W.; Gunawardana, D.; Lester, P.; Rees, J.; Stanley, M.; Sutherland, A.; Toft, R. 2005: Invasive ant pest risk assessment project for Biosecurity New Zealand. Series of unpublished Landcare Research contract reports to Biosecurity New Zealand. BAH/35/2004-1.
Summary: The invasive ant risk assessment project, prepared for Biosecurity New Zealand by Landcare Research, synthesises information on the ant species that occur in New Zealand (native and introduced species), and on invasive ants that pose a potential threat to New Zealand.
There is a great deal of information in this risk assessment on invasive ant species that is of global interest, including; biology, distribution, pest status, control technologies.
The assessment project has five sections.1) The Ants of New Zealand: information sheets on all native and introduced ants established in New Zealand
2) Preliminary invasive ant risk assessment: risk scorecard to quantify the threat to New Zealand of 75 ant species.
3) Information sheets on invasive ant threats: information sheets on all ant species scored as medium to high risk (n = 39).
4) Pest risk assessment: A detailed pest risk assessment for the eight species ranked as having the highest potential risk to New Zealand (Anoplolepis gracilipes, Lasius neglectus, Monomorium destructor, Paratrechina longicornis, Solenopsis geminata, Solenopsis richteri, Tapinoma melanocephalum, Wasmannia auropunctata)
5) Ranking of high risk species: ranking of the eight highest risk ant species in terms of the risks of entry, establishment, spread, and detrimental consequences.
NB. The red imported fire ant (Solenopsis invicta) is considered to be the worst ant pest in the world. However, Solenopsis invicta was specifically excluded from consideration in this risk assessment as this species has already been subject to detailed consideration by Biosecurity New Zealand
(This invasive ant pest risk assessment was funded by Biosecurity New Zealand and Foundation for Research, Science and Technology. Undertaken by Landcare Research in collaboration with Victoria University of Wellington and Otago Museum)
http://www.landcareresearch.co.nz/research/biocons/invertebrates/Ants/ant_pest_risk.asp [Accessed 20 May 2007]
11. Hartley, Stephen, Harris, Richard & Lester, Philip J., 2006. Quantifying uncertainty in the potential distribution of an invasive species: climate and the Argentine ant. Ecology Letters 9 (9), 1068-1079.
13. Holway, D.A., Lach, L., Suarez, A.V., Tsutsui, N.D. and Case, T.J. 2002a. The Causes and Consequences of Ant Invasions, Annu. Rev. Ecol. Syst. 33: 181-233.
14. Hooper, L. M. 1995. The biology of the Southern Fire Ant, Solenopsis xyloni (McCook) and its predation of the California Least Tern, Sterna antillarum browni (Mearns). MSc Thesis, University of California Riverside.
Summary: Masters thesis dealing primarily with Solenopsis xyloni, but also makes some references to Linepithema humile.
15. Hooper-Bui, L. and Rust, M. K. 2000. Oral toxicity of abamectin, boric acid, fipronil, and hydramethylnon to laboratory colonies of Argentine ants (Hymenoptera: Formicidae). Economic Entomology 93(3): 858-864.
Summary: Conducted laboratory tests of the effectiveness of four toxicants against the Argentine ant.
17. Krushelnycky, P. D. and Reimer, N. J. 1998. Bait preference by the Argentine ant (Hymenoptera: Formicidae) in Haleakala National Park, Maui, Hawaii. Environmental Entomology 27: 1482-1487.
Summary: A year-long study determining the seasonal preferences of baits that could potentially be used in control efforts.
18. Krushelnycky, P. D. and Reimer, N. J. 1998. Efficacy of Maxforce bait for control of the Argentine ant (Hymenoptera: Formicidae) in Haleakala National Park, Maui, Hawaii. Environmental Entomology 27: 1473-1481.
Summary: An initial attempt to eradicate Argentine ants from test plots in Haleakala National Park, using standard Maxforce bait as well as new bait varieties formulated with hydramethylnon. Was unsuccessful in achieving eradication.
20. Krushelnycky, P.D., Loope, L.L. and Joe, S.M. 2004. Limiting spread of a unicolonial invasive insect and characterization of seasonal patterns of range expansion, Biological Invasions 6: 47–57.
21. McGlynn, T.P. 1999. The Worldwide Transfer of Ants: Geographical Distribution and Ecological Invasions, Journal of Biogeography 26(3): 535-548.
22. Ness, J. H and Bronstein, J. L. 2004. The Effects of Invasive Ants on Prospective ant Mutualists, Biological Invasions 6: 445-461.
24. O’Dowd, D.J., Green, P.T. and Lake, P.S. 1999. Status, Impact, and Recommendations for Research and Management of Exotic Invasive Ants in Christmas Island National Park. Centre for the Analysis and Management of Biological Invasions: Clayton (Victoria, Australia).
26. Sarnat, E. M. (December 4, 2008) PIAkey: Identification guide to ants of the Pacific Islands, Edition 2.0, Lucid v. 3.4. USDA/APHIS/PPQ Center for Plant Health Science and Technology and University of California — Davis.
Summary: PIAkey (Pacific Invasive Ant key) is an electronic guide designed to assist users identify invasive ant species commonly encountered in the Pacific Island region. The guide covers four subfamilies, 20 genera and 44 species.
The primary tool offered by PIAkey is an interactive key designed using Lucid3 software. In addition to being fully illustrated, the Lucid key allows users to enter at multiple character points, skip unknown characters, and find the most efficient path for identifying the available taxa. Each species is linked to its own web page. These species pages, or factsheets, are linked to an illustrated glossary of morphological terms, and include the following seven sections: 1) Overview of the species; 2) Diagnostic chart illustrating a unique combination of identification characters; 3) Comparison chart illustrating differences among species of similar appearance; 4) Video clip of the species behavior at food baits (where available); 5) Image gallery that includes original specimen images and live images (where available); 6) Nomenclature section detailing the taxonomic history of the species, and 7) Links and references section for additional literature and online resources.
Available from: http://www.lucidcentral.org/keys/v3/PIAkey/index.html [Accessed 17 December 2008]
29. Tsutsui, N.D. and Suarez, A.V. 2003. The Colony Structure and Population Biology of Invasive Ants, Conservation Biology 17(1): 48-58.
30. van Schagen, J. J., Davis, P. R. and Widner, M. A. 1994. Ant pests of Western Australia, with particular reference to the Argentine ant (Linepithema humile). In Williams, D. F. (ed.) Exotic Ants: Biology, Impact and Control of Introduced Species: 174-180.
Summary: Reports on effort to eradicate the Argentine ant in Western Australia.
32. Walker, K. 2006. Argentine ant (Linepithema humile) Pest and Diseases Image Library. Updated on 29/08/2006 12:06:40 PM.
Summary: PaDIL (Pests and Diseases Image Library) is a Commonwealth Government initiative, developed and built by Museum Victoria's Online Publishing Team, with support provided by DAFF (Department of Agriculture, Fisheries and Forestry) and PHA (Plant Health Australia), a non-profit public company. Project partners also include Museum Victoria, the Western Australian Department of Agriculture and the Queensland University of Technology.
The aim of the project is: 1) Production of high quality images showing primarily exotic targeted organisms of plant health concern to Australia. 2) Assist with plant health diagnostics in all areas, from initial to high level. 3) Capacity building for diagnostics in plant health, including linkage developments between training and research organisations. 4) Create and use educational tools for training undergraduates/postgraduates. 5) Engender public awareness about plant health concerns in Australia.
PaDIL is available from : http://www.padil.gov.au/aboutOverview.aspx, this page is available from: http://www.padil.gov.au/viewPestDiagnosticImages.aspx?id=615 [Accessed 6 October 2006]
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