Tapinoma melanocephalum

The ghost ant, Tapinoma melanocephalum, is an ubiquitous indoor and outdoor pest throughout much of the tropics and subtropics, and an increasingly common indoor pest in temperate regions.

Identification
Distinctively bicoloured, head brown, alitrunk and gaster pale yellowish with variable brown patches; legs and antennae very pale. Prothorax laterally compressed, broadening anteriorly. Length: 1.5-2 mm. (Collingwood 1979)

Distribution
Tapinoma melanocephalum has one of the widest distributions known for any ant species. It has spread across the Old World and New World in both the northern and southern hemispheres. It is tropical and subtropical; at latitudes greater than 30°, it is largely restricted to living inside buildings. The only ants with broader known distributions than T. melanocephalum are the longhorn crazy ant, Paratrechina longicornis, and the pharaoh ant, Monomorium pharaonis. I expect that T. melanocephalum will eventually spread to the disturbed lowlands of virtually every tropical country. This species also appears to be an increasingly common indoor pest in temperate areas, and some-day may be found in every major city of the world. Because T. melanocephalum can live anywhere that humans live, there is no limit to the latitude where indoor populations of this species may be found. (Wetterer 2009)

This taxon was described from French Guiana. It is also found in the Philippines, United States, Cuba, United Kingdom of Great Britain and Northern Ireland, Guinea, Senegal, Ecuador, Dominican Republic and New Caledonia.

Biology
Wetterer (2009) - "Tapinoma melanocephalum is a ubiquitous pest through much of the tropics and subtropics. As Longino (2006) aptly wrote: "regardless of whether you are in Guinea, New Guinea, or Guyana, if you are sitting at a table with a sugar dispenser you are likely to see workers of T. melanoce-phalum running about on the surface." Workers are small (~ 1.5 mm) and their pale legs and abdomens often blend into the background, making them difficult to see. Their dark brown heads and thoraces often look like hovering specks, unrecognizable as ants. The barely visible "ghostly" appearance of T. melanocephalum no doubt explains its common name.

Tapinoma melanocephalum is particularly noted as a pest in homes, restaurants, hospitals, and greenhouses. For example, T. melanocephalum was the most common house ant in Brazil (e.g., Kamura et al. 2007) and on Panang Island, Malaysia (Lee et al. 2002), and it was the most fre-quently reported pest ant in greater Miami (Klotz et al. 1995). Wheeler (1907) noted that T. melanocephalum had been "introduced into well-heated buildings in New York," and observed workers in the winter "visiting the sugar bowls on the tables of the Columbia University commons." Karawajew (1926) reported T. melanocephalum from hotel tables both on Ambon Island, Indonesia and in Vladivostok, Russia. James Trager (pers. comm.) observed T. melanocephalum inside the Sachs Butterfly House in Chesterfield, Missouri, beginning shortly after it opened in 1995. Tapinoma melanocephalum also has been a long term problem in the greenhouses of the Dow Estate in Midland, Michigan, where fumigation is incompatible with a butterfly exhibit (J. LaForest, pers. comm.).

Although T. melanocephalum does not sting and its bite is not very painful (pers. obs.), it can be a serious pest. For example, Fowler et al. (1993) and Moreira et al. (2005) found that T. melanocephalum was the most prevalent ant in hospitals in Brazil, and had the highest potential as a vector for pathogens. In fact, Moreira et al. (2005) found at least 14 different types of bacteria on T. melanocephalum workers collected in the hospitals, including antibiotic resistant strains. Tapinoma melanocephalum also can be an agricultural pest because it tends populations of phloem feeding Hemiptera, such as mealybugs, scale insects, and aphids, for their honeydew (Venkataramaiah and Rehman 1989). Hemiptera cause damage by sapping plants of nutrients and increasing the occurrence of diseases, including viral and fungal infections. Fowler et al. (1994) concluded that T. melanocephalum had a great impact on other ant species on banana plantations in Brazil. Under some conditions, T. melanocephalum may be beneficial as a biocontrol agent. For example, Osborne et al. (1995) found that in greenhouses of central Florida, naturally occurring populations of T. melanocephalum were important in controlling a serious plant pest, the two-spotted spider mite, Tetranychus urticae Koch, 1836.

Whereas T. melanocephalum is most prevalent in disturbed habitats, it has also been reported from natural reserves around the world, including the Baiyer River Wildlife Sanctuary in Papua-New Guinea (Whalen and Mackay 1988), Reserva Biológica de Una in Brazil (Delabie et al. 1997), primary rainforest in Chocó, Colombia (Armbrecht et al. 2001), and on many Galapagos islands (Causten et al. 2006). In the Wapoga River Area of Irian Jaya, Indonesia, Snelling (2000) found that T. melanocephalum "had successfully invaded forest areas where they apparently became quickly assimilated into the native mix; their presence did not seem to adversely affect other ant species there. This apparently benign situation probably would be reversed in the presence of continued disturbance of the habitat."

Tapinoma melanocephalum colonies are polygynous and frequently relocate their nests. In a matter of hours, colonies can move into cargo, which is then shipped worldwide. In fact, Lester (2005) reported that T. melanocephalum was the second most common ant species (after Pheidole megacephala) intercepted in freight entering New Zealand between 1997 and 2002. Weber (1939) reported collecting T. melanocephalum from riverboats in Venezuela and Guyana and on a ship between Haiti and New York. Tapinoma melanocephalum was found on a train in France, traveling from Paris to Rennes (X. Espadaler, pers. comm.). In Le Carbet, Martinique, a T. melanocephalum colony moved overnight into luggage packed for departure, requiring me to shake out everything before repacking."

Nomenclature

 *  melanocephalum. Formica melanocephala Fabricius, 1793: 353 (w.) FRENCH GUIANA. Emery, 1887a: 249 (m.); Forel, 1891b: 102 (q.); Wheeler, G.C. & Wheeler, J. 1951: 197 (l.); Crozier, 1970: 119 (k.). Combination in Micromyrma: Roger, 1862b: 258; in Tapinoma: Mayr, 1862: 651; in Tapinoma (Micromyrma): Santschi, 1928e: 475. Senior synonym of pellucida: Mayr, 1886c: 359; of nana: Emery, 1892b: 166; of familiaris: Forel, 1899c: 101; of australis: Wilson & Taylor, 1967: 80; of australe: Bolton, 1995b: 401. Current subspecies: nominal plus coronatum, malesianum. See also: Smith, D.R. 1979: 1421; Shattuck, 1994: 148.
 * nana. Formica nana Jerdon, 1851: 125 (w.) INDIA. [Unresolved junior primary homonym of Formica nana Latreille, 1802c: 263.] Junior synonym of melanocephalum: Emery, 1892b: 166.
 * pellucida. Myrmica pellucida Smith, F. 1857a: 71 (w.) SINGAPORE. Junior synonym of melanocephalum: Mayr, 1886c: 359.
 * familiaris. Formica familiaris Smith, F. 1860b: 96 (w.) INDONESIA (Batjan I.). [Unresolved junior primary homonym of Formica familiaris Smith, F. 1860a: 68 (now in Pseudolasius).] Junior synonym of melanocephalum: Forel, 1899c: 101.
 * australe. Tapinoma (Micromyrma) melanocephalum var. australe Santschi, 1928e: 475 (w.) VANUATU. Junior synonym of melanocephalum: Bolton, 1995b: 399. [Note. Shattuck, 1994: 148 treats australis and australe as variant spellings, but the type-localities of the two are different and the names must be treated as separate.]
 * australis. Tapinoma (Micromyrma) melanocephalum var. australis Santschi, 1928a: 53 (w.) SAMOA. Junior synonym of melanocephalum: Wilson & Taylor, 1967: 80.

Additional References

 * Collingwood, C. A. 1979. The Formicidae (Hymenoptera) of Fennoscandia and Denmark. Fauna Entomol. Scand. 8:1-174.


 * Wetterer, J. K. 2009. Worldwide spread of the ghost ant, Tapinoma melanocephalum (Hymenoptera: Formicidae). Myrmecol. News. 12:23-33.