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According to the IUCN/SSC Invasive Species Specialist Group A. gracilipes is among the 100 most pervasive and destructive invasive species in the world (Lowe, et al., 2000), and is most notably implicated in the 'ecological meltdown' of Christmas Island (O'Dowd, et al., 2001;2003). Introduced populations of Anoplolepis gracilipes can exhibit unicolonial behavior by forming multiple, populous high-density supercolonies. On Christmas Island, A. gracilipes was recorded to achieve the highest density of foraging ants ever recorded (Abbott, 2005). Colonies are polydomous and polygynous and disperse by budding. Nests occasionally hosting hundreds of queens and thousands of workers. The species has generalized foraging and nesting habits, and often achieve high densities in agricultural landscapes. Part of the species invasion success has been attributed to its strong mutualisms with nectar and honeydew producing insects like scales and aphids.
Among introduced ants, Anoplolepis gracilipes might be mistaken for Paratrechina longicornis
(the Black Crazy Ant), which also has very long antennae and legs and eyes
that break the outline of the head in full face view. In addition to the
difference in color, A. gracilipes can also be distinguished by the lack
of erect hairs on the mesosoma, petiole and gaster. Anoplolepis gracilipes can
also be mistaken for species of Leptomyrmex and Oecophylla
because of their similar sizes and very long limbs. Anoplolepis can be
distinguished from Leptomyrmex by the
presence of an acidopore. Anoplolepis can be distinguished from Oecophylla
by the more compact petiole.
Diagnosis among introduced and commonly intercepted ants.
Antenna 11-segmented. Antennal club indistinct. Antennal scape length greater than 1.5x head length. Eyes large; break outline of head. Antennal sockets and posterior clypeal margin separated by a distance equal to or greater than the minimum width of antennal scape. Dorsum of mesosoma with metanotal impression, but never with a deep and broad concavity. Metapleuron with a distinct gland orifice. Propodeum and petiolar node both lacking a pair of short teeth. Propodeum lacking posteriorly projecting protrusion. Propodeal declivity less than twice length of propodeal dorsum. Waist 1-segmented. Petiole upright and not appearing flattened. Gaster armed with acidopore. Distinct constriction not visible between abdominal segments 3+4. Hairs not long thick and produced in pairs. Yellowish-brown to reddish-brown. Monomorphic.
Male identification among New World Formicinae
Antenna 12-merous; mandible with 8-9 denticles, with one or two offset denticles on basal margin; maxillary palps longer than maximum compound eye length; scape more than twice head length; compound eyes situated at about head midlength.
Abbott, K.L. (2005) Supercolonies of the invasive yellow crazy ant, Anoplolepis gracilipes, on an oceanic island: Forager activity patterns, density and biomass. Insect. Soc., 52, 266-273.
Lowe, S., Browne, M., Boudjelas, S. & De Poorter, M. (2000) 100 of the world's worst invasive species. Aliens, 12, s1-s12.
O'Dowd, D.J., Green, P.T. & Lake, P.S. (2001) Invasional meltdown in island rainforest. In: Ganeshaiah, K.N., Shaanker, R.U. & Bawa, K.S. (Eds.) Tropical ecosystems. Structure, diversity and human welfare. Oxford and IBH, New Delhi, pp. 447-450.
O'Dowd, D.J., Green, P.T. & Lake, P.S. (2003) Invasional 'meltdown' on an oceanic island. Ecol. Lett., 6, 812-817.Wetterer, J.K. (2005) Worldwide distribution and potential spread of the long-legged ant, Anoplolepis gracilipes (Hymenoptera: Formicidae). Sociobiology, 45, 77-97.
Found most commonly in these habitats: 12 times found in Rainforest, 2 times found in sugar cane field, 5 times found in forest, 6 times found in degraded dry forest, 3 times found in port of entry/city, 9 times found in Secondary forest, 4 times found in palm forest, 7 times found in coastal forest, 6 times found in coastal scrub, 7 times found in Disturbed forest, ...
Found most commonly in these microhabitats: 88 times malaise trap, 16 times ground forager(s), 2 times under stone, 3 times sifted litter (leaf mold, rotten wood), 9 times sifted litter, 2 times recruiting to bait, 7 times on low vegetation, 7 times litter sample, 4 times ex rotten log, 1 times nesting in tree, 3 times leaf litter (1 sq meter), ...
Collected most commonly using these methods: 103 times M, 27 times pan traps, 23 times Malaise trap, 18 times Davis sifting>hand collected|aspirator, 6 times H, 2 times 2 Maxi Winks, 4 times sweeping, 15 times Malaise traps, 14 times hand collected|aspirator, 9 times L, 12 times hand collected|aspirator>bait trap|peanut butter, ...
Elevations: collected from 1 - 1220 meters, 203 meters average