Little fire ant case studies
Port Vila, Vanuatu : Maui, Hawaii : Marchena Island, Galapagos Islands : Smithfield, Australia
Location: Port Vila, Vanuatu
| Justification: Containment
Goal: Eradication Size: 8.5 ha Products: Maxforce Fire Ant Granules (hydramethylnon; 10 g/kg; protein based granular matrix; 2 kg/ha) was spread over the open areas using hand spreaders, while Xstinguish (fipronil; 0.1 g/kg; lipid and protein based paste; 3 kg/ha) in paste form was applied to vegetation and trees (larger trees were climbed) using a caulking gun. The paste bait was applied to foliage by the operator swinging the caulking gun while simultaneously squeezing the trigger (the Kilukilu method). |
Granular bait being distributed using a hand spreader (© Cas Vanderwoude) |
Time of year: October
Outcome: Within 24 hours the number of workers observed was substantially reduced.
Programme cost: not available
Manager: Casper Vanderwoude (casperv@hawaii.edu)
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Paste bait being applied to foliage using the Kilukilu method (© Cas Vanderwoude) |
Small pieces of bait are showered on infested plants (© Cas Vanderwoude) |
Information sources
Vanderwoude. 2007. Little fire ant (Wasmannia auropunctata) in Port Vila: report to Secretatiat of the Pacific Community on activities 4-14th October 2007, and recommendations for future management. Unpublished report to Secretariat of the Pacific Community, VCL New Zealand
case study reviewed by Cas Vanderwoude, Hawai'i Ant Lab, January 2017
Maui, Hawaii, USA
Justification: Containment
Goal: Eradication
Size: 0.5 ha
Products: Esteem (pyriproxyfen; 5 g/kg; 2 kg/ha; corn grit carrier); Probait (hydramethylnon; 7.4 g/kg; 2 kg/ha); Indoxacarb (1.8 g/kg; 4.9 kg/ha; peanut butter mixture)
Time of year: Every month
Outcome: Eradication successful
Programme cost: not available
Manager: Casper Vanderwoude (casperv@hawaii.edu) / Michelle montogomery (michelle.montgomery@littlefireants.com)
Treatment began one month after the initial detection of a 0.5 ha infestation of little fire ants (LFA) on a large residential property on Maui, Hawaii.
Esteem® (used on crop areas) and Probait® (used on turf and ornamental garden areas) were applied once a month for 12 months using hand spreaders. Indoxacarb in a peanut butter and xanthan gum mixture was applied to all vegetation over 1.8 m high using a compressed air gun, which shoots out the paste-like mixture, once a month. A 20 m buffer zone around the infestation was also treated.
No little fire ants were detected after fifth treatment, and the eradication is believed to be successful.
Two factors are believed to be responsible for this success where other little fire ant eradication programmes in Hawai'i have failed:
- treating the canopy not just the ground, as little fire ants also nest high up in vegetation and don’t necessarily come down to the ground to forage.
- continuing treatment even after no more little fire ant workers were detected. This approach may be particularly important in tropical climates, where ant colonies can grow all year round.
The gel baits used by Hawai'i Ant Lab are particularly useful in areas where rainfall is frequent, or areas with very high and vegetation or steep topography (hills and cliffs) such as French Polynesia. Aerial application of the gel baits is also being used by SOP Manu in French Polynesia. Contact Caroline Blanvillain for more information.
Information sources
Vanderwoude, Nadeau. 2009. Application methods for paste bait formulations in control of ants in arboreal situations. Proceedings of the Hawaiian Entomological Society 41: 113-119
Vanderwoude, Onuma, Reimer. 2010. Eradicating Wasmannia auropunctata (Hymenoptera: Formicidae) from Maui, Hawaii: the use of combination treatments to control an arboreal invasive ant. Proceedings of the Hawaiian Entomological Society 42: 23-31 DOI: http://scholarspace.manoa.hawaii.edu/handle/10125/19914
case study reviewed by Cas Vanderwoude, Hawai'i Ant Lab, January 2017
Location: Marchena Island, Galapagos Islands, Ecuador
Justification: Conservation
Goal: Eradication
Size: 21 ha
Products: Amdro (hydramethylnon; 8.8 g/kg; corn grit/soybean oil granule; 4.9 kg/ha)
Time of year: March to October (end of warm/wet season – cool/dry season)
Outcome: Successfully eradicated
Programme cost: 223 000 USD
Manager: Charlotte Causton (Charlotte.causton@fcdarwin.org.ec), Charles Darwin Research Station
A 21 ha infestation of little fire ants (LFA) were targeted for eradication on Marchena Island, an uninhabited island in the Galapagos. This island is little-visited. The ants were found near the coast and there was concern that ants would be spread by birds or animals to other parts of the island.
Amdro was applied to the infested area and an additional 6 ha (buffer zone) at a rate of double the quantity recommended (4.9 kg/ha instead of 2.2 kg/ha). This dosage was recommended by experts because of the hilly terrain and the presence of caves and dense vegetation. Bait was only dispersed after 3 pm to minimize its exposure to sunlight as hydramethylnon breaks down in direct sunlight
The granules were spread by hand over the treatment area up to three times between March and October 2001 (3 months between applications). The third treatment was only applied to areas that still had LFA after two treatments. Two very small areas of LFA were found in April and October 2002 and re-treated using the same method.
The treatment area was intensively monitored (grid size of 3 m) for LFA six and 12 months after the first application and on five more occasions (up to 2010). Ants were monitored using sticks painted with peanut butter.
As of 2003 no LFA have been detected in this area on Marchena demonstrating the efficacy of the methods used. However, in 2008 LFA were found about 2 km from the coast. Island-wide surveys in 2000-2003 did not detect this population. Its distribution (~70 ha) suggests that LFA has been present for at least 20 years. This area has been targeted for management, but the topography and size of the area requires a different strategy from that used on the coast.
Information source
Causton, Sevilla, Porter. 2005. Eradication of the little fire ant, Wasmannia auropunctata (Hymenoptera: Formicidae), from Marchena Island, Galapagos: on the edge of success? Florida Entomologist 88(2): 159-168
Causton, Sevilla, Cabrera, Carrion, Carrion. 2012. Evaluación del Manejo de Hormigas Invasoras Galápagos. Reporte técnico. Fundación Charles Darwin, Dirección Parque Nacional Galápagos, Island Conservation. 80pp
case study reviewed by Charlotte Causton, Charles Darwin Foundation, November 2016
Location: Smithfield, Queensland, Australia
Justification: Social, environmental, economic
Goal: Eradication
Size: 390 ha (over the course of the programme)
Products: Campaign (hydramethylnon; 7.3 g/kg; corn grit/soybean oil granule; 5 kg/ha); Engage P (S-methoprene; 5 g/kg; corn grit/soybean oil granule; 5 kg/ha), both with added protein
Time of year: Year round (subject to prevailing weather conditions)
Outcome: The programme is ongoing, but the majority of treated infestations have a 100% reduction in little fire ants after three to six treatments
Programme cost: approximately 12.85 million AUD after 10 years
Manager: Gary Morton (gary.j.morton@daf.qld.gov.au), Biosecurity Queensland
When little fire ants were found near Cairns, Australia the decision to immediately eradicate them was made.
Campaign and Engage P + are applied using hand spreaders, or mechanical blowers in areas of high vegetation, up to 6 times per year depending on infestation size, age and density. A minimum 50 m buffer zone around each infestation is also treated. Persistent infestations are re-treated until they are eradicated.
Engage + (S-methoprene) is only used in wet areas, or areas within 8 m of water. It was found early in the programme that LFA greatly preferred Engage P, which has 5% added protein, to Engage. Campaign is not used within 10 m of water.
Infestations that are less than one year old, OR that are less than 1 ha receive only 3 rounds of treatment instead of 6 (though further rounds of treatment are applied if necessary). Treatments are done at intervals of at least 4 weeks. This allows time for the treatment to take effect, and also avoids bait shyness.
Infested pot plants are either treated with liquid chlorpyrifos, an organophosphate, or cyfluthrin, a pyrethroid. These are used because the plants can be completely drenched, killing all ants. This approach would not be recommended in for other applications (e.g. broadcast into the environment). The programme is ongoing, but the majority of treated infestations have had a 100% reduction in little fire ants after six treatments.
As of 31st December 2016, little fire ants have been confirmed eradicated from 85.5 ha (after 2 years of monitoring).
This programme also uses sniffer dogs trained to detect little fire ants with great success.
In addition the programme has been trialing gel baits similar to those used by the Hawai'i Ant Lab. The benefit of these gel baits is that they re-hydrate after rain, so are good in areas that a prone to year-round rain. In Queensland they have found that little fire ants first retreat from the trees when their populations start to decline (i.e., after the first treatment). At that point Campaign is used to treat the remaining nests on the ground.
Information sources
Further information was provided by Christine Horlock, A/Manager Programme Support, Biosecurity Queensland Control Centre, DAF. and Gary Morton, Biosecurity Queensland
Cairns Post, Little fire ants in Cairns
Lach, Barker. 2013. Assessing the effectiveness of tramp ant projects to reduce impacts on biodiversity. A report prepared for the Australian Government Department of Sustainability, Environment, Water, Population, and Communities
case study reviewed by Gary Morton, Biosecurity Queensland, February 2017