Monomorium destructor (Singapore ant)

Other: Most significant is human-mediated dispersal, without which the ant may never have reached its current locations. M. destructor is a tramp ant, renowned for transportation via human commerce and trade. It is associated with a wide range of freight types, making it difficult to target any particular pathways (Harris et al. 2005).People sharing resources:M. destructor is a successful tramp species that has become very widely dispersed by trade (Harris et al. 2005).

Natural dispersal (local): M. destructor also spreads naturally from established colonies in two ways: colony budding, where queens walk on foot accompanied by workers to a new nesting site; and winged dispersal of inseminated queens to uninfested areas where they start a new colony. This latter mechanism needs to be confirmed; it is most likely colony budding is the primary natural dispersal method (Harris et al. 2005).

The Singapore ant (Monomorium destructor) is a slow moving ant that forages along narrow trails. A generalist with a broad diet of living and dead insects, insect eggs, carbohydrates from tending sap-sucking insects, nectar, seeds; it will forage for sweets, fats and proteins. In households they will feed on almost any food available. M. destructor foragers are slow to find food compared with other tramp ants (Ferster et al. UNDATED; and Harris et al. 2005).

Singapore ant (Monomorium destructor) form large colonies with multiple queens (Ferster et al. UNDATED).

Compiled by the IUCN SSC Invasive Species Specialist Group (ISSG)

1.0 Preventative measures
Prevention, quarantine and rapid response are the best management strategies for preventing the establishment of invasive ants. To be successful they require active surveying, early detection and subsequent rapid treatment procedures often along with quarantines. This type of management approach remains the most practical strategy for dealing with invasive ants (Krushelnycky Loope and Reimer 2005).
1.1 Risk Assessments
The first step to solving any problem is to identify whether it exists and define what it is. Preparing risk assessments is a vital management tool for addressing the issue of invasive ants in a country or region.
In New Zealand an invasive ant risk assessment project (prepared for Biosecurity New Zealand by Landcare Research) identified ant species which pose the greatest potential threat to New Zealand. This project was divided into five sections: (i) gathering data on native and non-native New Zealand ants, (ii) producing a preliminary risk, (iii) producing information sheets on medium-risk and high-risk taxa, (iv) producing a detailed pest risk assessment for the eight highest-risk species, and (v) re-ranking these eight species. Of the 75 ant taxa which were ranked the following ants present the greatest potential risk to New Zealand: Anoplolepis gracilipes, Lasius neglectus, Monomorium destructor, Paratrechina longicornis, Solenopsis geminata, Solenopsis richteri, Tapinoma melanocephalum and Wasmannia auropunctata (Harris undated). An assessment of the current risk of M. destructor establishing itself in New Zealand (based on climate similarity of native and introduced ranges) lead to the prediction that it would be unlikely to establish outside but may achieve limited distribution in heated buildings (Harris unpubl. data, in Stanley 2004).
1.2 Ant Prevention in the Pacific Region
The Pacific island region includes over 25 countries, most of which are served by two important regional international organizations, the Secretariat of the Pacific Community (SPC), which addresses agricultural issues, and the South Pacific Regional Environment Programme (SPREP), which addresses biodiversity issues. The biodiversity of the Pacific is particularly vulnerable to effects of invasive species (SPREP 2000).
Special concern regarding ant invasions has arisen now that the red imported fire ant occurs at or near the coast on both sides of the Pacific, and the little fire ant has arrived in Hawaii and is spreading in the western Pacific. These and other species threaten all Pacific islands, including Hawaii and the U.S. affiliated islands of Guam, Commonwealth of the Northern Marianas, Federated States of Micronesia, American Samoa, and Palau.
The SPC-Plant Protection Service (SPC-PPS) works in partnership with 22 Pacific members to maintain effective quarantine systems and to assist with regionally coordinated eradication/containment efforts. Priorities for emphasis are determined by member countries, which meet periodically as the Pacific Plant Protection Organization (PPPO).
A workshop sponsored by the Invasive Species Specialist Group (ISSG) of IUCN was held in Auckland, New Zealand, in September 2003, and resulted in the compilation of a draft Pacific Ant Prevention Plan (Pacific Invasive Ant Group 2004). The Pacific Ant Prevention Plan was presented to and embraced by 21 Pacific island countries and territories present at a PPPO meeting, the “Regional Biosecurity, Plant Protection and Animal Health” meeting held by SPC in Suva, Fiji, in March 2004 (Pacific Plant Protection Organization 2004). Like Hawaii’s Red Imported Fire Ant Prevention Plan, the Pacific Ant Prevention Plan is still a conceptual work, but ISSG and others are working toward obtaining the international funding needed to implement the plan with the assistance of SPC. The project presents an exceptional opportunity for agriculture and conservation interests to work together with international and bilateral aid entities at regional and country levels to build much needed quarantine capacity. Increased quarantine protection is desperately needed by PICT in order to address invasions that jeopardize both agriculture and biodiversity.
The information for this section was sourced directly from Krushelnycky Loope and Reimer (2005).

2.0 Chemical
2.1 General Considerations
Most if not all ant eradications have employed the use of baits and toxicants, many of which are developed for agriculture or urban settings. However, indiscriminate pesticide use in natural areas and fragile island ecosystems is not advocated. While some toxins such as hydramethylnon break down quickly in the environment, any and all pesticide use is likely to be accompanied by at least some undesirable non-target effects. These include increased runoff or drift outside the intended area, adverse affects on beneficial insects and non-target impacts on native species (Krushelnycky Loope and Reimer 2005).
Non-target impacts must be weighed up carefully against the benefits of ant eradication. Cleary, treating whole ecosystems or islands is too risky as entire populations of rare invertebrates may be at risk of extinction. On the other hand, eradicating populations of exotic ants before they become established in a natural ecosystem or island has the potential to prevent the potentially disastrous consequences of ant invasions (Krushelnycky Loope and Reimer 2005).
Baits should be designed with the specific foraging strategies of the target ant in mind. The preferred size, type and dispersal of bait and the nesting, foraging and behavioural traits of the ant should be considered in the planning stages of the operation. The use of appropriately designed and chosen baits and toxins will help reduce the impact of toxins on native ants and non-target fauna (McGlynn 1999).
2.2 Bait Design
Field trials in Malaysia using food attractants found peanut butter (80% of ants) was strongly preferred over honey (20% ants) by M. destructor (Lee 2002, in Stanley 2004). Lee and Kooi (2004, in Stanley 2004) recommend using protein or sugar-based attractants in baits targeting M. destructor. Davis et al. (1993b) found the soybean oil on corn grit bait matrix used is attractive to M. destructor in Western Australia. In food preference tests, plain white bread was the most attractive of a range of food types to M. destructor and was used to monitor ant activity before and after treatments were applied (Davis et al. 1993b).
2.3 Ant Toxins
Ant toxins can be classed into three categories: “stomach” poisons (or metabolic inhibitors), Insect Growth Regulators (IGRs) and neurotoxins. Stomach toxins include hydramethylnon (eg: Maxforce® or Amdro®), sulfuramid and sodium tetraborate decahydrate (eg: Borax). IGRs include compounds such as methoprene, fenoxycarb or pyriproxyfen. Neurotoxins include fipronil (eg: Xstinguish®). Stomach poison kills all workers and reproductives it comes into contact with. IGRs work by disrupting development of the queens ovarian tissues, effectively sterilising the colony. Neurological inhibitors disrupt insect central nervous systems by blocking neuron receptors. The onset of mortality is contingent upon the type of active ingredient. In general, ant baits that contain active ingredients that are metabolic inhibitors have a two to three day delay before extensive mortality occurs in the colony (Oi Vail and Williams 2000). Baits containing IGRs take several weeks before colony populations are reduced substantially (Oi Vail and Williams 2000). The latter (IGRs) provide gradual long-term control, while metabolic inhibitors provide short-term, localised and rapid control (Oi Vail and Williams 2000). This is because while stomach poisons are faster than IGRs, they sometimes eliminate workers before the toxin can be effectively distributed throughout the colony (O’Dowd Green and Lake 1999).
Amdro® is attractive and effective at controlling M. destructor. Stanley (2004) recommends following bait recommendations for S. invicta (ie: use Distance® (pyriproxyfen) for gradual control and Engage® (methoprene) near water bodies, follow up treatment with Amdro®. Both Engage® (methoprene) and Distance® (pyriproxyfen) have a lipid attractant and are therefore likely to be attractive to M. destructor.
Davis et al. (1993b, in Stanley 2004) trialled several commercial ant baits developed for S. invicta with the soybean oil on corn grit bait matrix: Finitron® (sulfluramid); Ascend® (abamectin); Award® (fenoxycarb); Amdro®  (hydramethylnon); and Bushwacker® (boric acid in ground shrimp offal bait matrix). Finitron®, followed by Ascend® and Amdro®, were the most effective ant baits, with ant abundance reduced to almost zero (Davis et al. 1993b). However, while there was an untreated ‘control’ plot, there was no replication in this field trial, making it difficult to interpret the results. The efficacy of Finitron®, Ascend® and Amdro® was also tested in replicated laboratory trials with M. destructor colonies (Davis et al. 1993b). Each bait proved equally effective at killing workers while Amdro® caused significantly more queen mortality (75% queen mortality) (Davis et al. 1993b). Finitron® (sulfluramid) has been withdrawn from the US market since the Western Australian trials. The results of these trials resulted in the registration of Amdro® throughout Australia for the control of M. destructor (J. van Scahgen, pers. comm., M. Widmer, pers. comm., in Stanley 2004). At least four formulations containing hydramethylnon (Drax Ant Kil Granular with Hydramethylnon; Garrards Granular Ant Bait; Faslane Granular Ant Bait and Maxforce Granular Insect Bait) are also registered for use against M. destructor in Australia. Several of the more recent commercial baits developed for S. invicta control, such as
indoxacarb and those containing IGRs, would be likely candidates for the effective control of M. destructor, although this requires testing (Stanley 2004).
Hickman and Bieman (2004) report effective control of M. destructor with a dual treatment of Termidor for exterior application and Phantom for indoor application.

3.0 Research
3.1 Bait and Toxin Research
Stanley (2004) suggests that future research on W. auropunctata focus on:
• Trialling the attractiveness and efficacy of Distance® and Engage® on as many high risk species as possible (e.g. S. geminata; M. destructor; W. auropunctata).
• Comparing the attractiveness and efficacy of Distance®, Engage®, Amdro®, Advion®, Xstinguish® and Chipco Firestar® to verify that S. invicta baits are adequate for M. destructor
3.2 Biosecurity New Zealand
Biosecurity New Zealand, the branch of government responsible for managing invasive species, has responded to a series of incursions of exotic invasive ant species by relying heavily on a small number of baits and toxins. The absence of a wide variety of effective baits may compromise the success of incursion responces. As a first step to ensuring effective incursion response, Biosecurity New Zealand commissioned Landcare Research to research and review international literature about the baits and toxins used for ant control (see Stanley 2004). The next step will be testing the most promising of these against a selected group of high-risk invasive ant species.

Harris, R. Undated. Invasive Ant Pest Risk Assessment Project. [Accessed 29 March 2007, from: http://issg.appfa.auckland.ac.nz/database/species/reference_files/Ant_RA/overview.pdf] This document describes an ant risk assessment and ranking project.
Krushelnycky, P.D., Loope, L.L. and Reimer, N.J. 2005. The Ecology, Policy, and Management of Ants in Hawaii, Proc. Hawaiian Entomol. Soc. 37. Accessed 2 April 2007, from http://www.ctahr.hawaii.edu/peps/museum/ant_website/Krushelnycky_et_al_Ant_review2005.pdf]
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). [Accessed 4 April 2007, from: http://www.issg.org/database/species/reference_files/Christmas_Island_Report.pdf]
Oi, D.H., Vail, K.M. and Williams, D.F. 2000. Bait distribution among multiple colonies of Pharaoh ants (Hymenoptera: Formicidae), Journal of Economic Entomology 93 (4): 1247 - 1255. [Accessed 13 Friday 2007, from: http://www.bioone.org.ezproxy.auckland.ac.nz/archive/0022-0493/93/4/pdf/i0022-0493-93-4-1247.pdf]
Stanley, M.C. 2004. Review of the Efficacy of Baits Used for Ant Control and Eradication (Landcare Research Contract Report: LC0405/044). [Accessed 29 March 2007, from: http://www.landcareresearch.co.nz/research/biocons/invertebrates/ants/BaitEfficacyReport.pdf]