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   Technomyrmex albipes (insect)
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    Taxonomic name: Technomyrmex albipes (Smith, 1861)
    Synonyms: Formica (Tapinoma) albipes Smith, Formica albipes, Tapinoma albipes (Smith), Tapinoma albitarse Motschoulsky, Tapinoma nigrum Mayr, Technomrmex albipes var. vitiensis Mann., Technomyrmex albipes st. rufescens Santschi, Technomyrmex detorquens Walker
    Common names: ashijiro-hirafushi-ari (Japanese), white-footed ant (English), white-footed house ant (English)
    Organism type: insect
    Native to the Indo-Pacific area, Technomyrmex albipes, commonly known as the white-footed ant, has spread to Australia, Africa, North America, Caribbean and Asia. Technomyrmex albipes are often found on cut flowers and other imported plants. It's penchant for invading houses and nesting in wall cavities distresses homeowners. The unusual colony structure of Technomyrmex albipes allows them to reproduce rapidly, especially in warm weather, reaching numbers in the millions in some locations. Management of Technomyrmex albipes is difficult when populations abound, as chemical poisons are not transferred between workers.
    Description
    Technomyrmex albipes is a small, black ant with whitish legs (Robertson, 2004) that is approximately 2-4mm in total length. (Tenbrink & Hara, 1992). Generally, the mandibles have 7-10 large teeth and between 2-15 dentricles. The front margin of the clypeus has broad, shallow concavity in the middle, or a distinct central notch. "The petiolar scale is reduced or absent." Workers differ slightly from the above description, having 12 segmented antennae, mandibles with 10 teeth, and numerous dentricles. Their bodies are usually dark brown with pale legs and the petiolar node of the worker ant is flattened. (Harris et al. 2004). T. albipes can form large colonies with numbers ranging from 8,000 to 3,000,000 in one colony, making them very difficult to control. (PAPP, 2004). While in motion, workers raise their abdomen, distinguishing them from other ants in the colony. (Warner & Scheffrahn, 2004). Foragers lay trail pheromones so that nestmates may be recruited to help when resources are located. On structures, foragers follow lines and edges, usually going in straight lines. (Warner et al, 2002)

    Please click on AntWeb: Technomyrmex albipes for more images and assistance with identification. The AntWeb image comparison tool lets you compare images of ants at the subfamily, genus, species or specimen level. You may also specify which types of images you would like to compare: head, profile, dorsal, or label.
    Please see PaDIL (Pests and Diseases Image Library) Species Content Page Ants: white-footed ant for high quality diagnostic and overview images.

    Please follow this link for a fully illustrated Lucid key to common invasive ants [Hymenoptera: Formicidae] of the Pacific Island region [requires the most recent version of Java installed]. The factsheet on Technomyrmex albipes contains an overview, diagnostic features, comparision charts, images, nomenclature and links. (Sarnat, 2008)

    Similar Species
    Linepithema humile, Paratrechina bourbonica, Technomyrmex difficilis

    More
    Occurs in:
    natural forests, planted forests, ruderal/disturbed
    Habitat description
    T. albipes is a scavenger that tramps/exploits forests and open habitats. Tent-like nests made from debris (Tenbrink & Hara, 2002) are found in dry places above the ground, mainly in trees, bushes, under palm fronds, in loose mulch, leaf litter, (Warner et al, 2002) rotting logs, under loose bark, and sometimes under stones (in soil). They can be found indoors searching for food and water, often forming long foraging lines. Indoor nests are often found in wall cavities (Warner & Scheffrahn, 2004) and attics. (Warner et al, 2002). T. albipes lives in areas with an elevation between 1000-5000 feet (305-1524 metres) and where annual rainfall exceeds 60 inches (1524mm). (Tenbrink & Hara, 1992)
    General impacts
    In households, T. albipes is considered a pest because it is found foraging in kitchens, bathrooms, and building exteriors. (PAPP, 2004) They are also attracted to contact points of light switches, which causes the switches to fail after repeated contact. The first indication of a light switch issue is a flickering light or sparks that can be seen through the switch cover in the dark. After a few days the switch ceases working. A dozen or more ants are usually found between the switch contacts forming an insulation. Other bodies are found below the contacts. Only 20% of the switches in a house are periodically affected; the cause of this fact is unknown. (Little, 1984). T. albipes can reach large numbers in buildings and is difficult to control. Impacts in their native habitat are unknown.

    As an arboreal species, T. albipes should occupy a different niche than ground nesting ants, therefore having little impact on them. (Warner & Scheffrahn, 2004). The symbiotic relationship between homopterans (aphids, mealybugs, and scale insects) causes agricultural problems in some parts of the world where farmers have attempted to erradicate the sap-sucking homopterans, usually with biological controls. (PAPP, 2004). The homopterans, protected by T. albipes, sap plants of nutrients and help promote plant disease through honeydew residues left on leaves. (Wetterer, 1997). Sri Lanka has experienced problems with T. albipes spreading pineapple wilt disease because they protect the pink mealybug (Dysmicocus brevis). South African citrus orchards have seen localised outbreaks of red scale insects (Aonidella aurantii) because of the presence of T. albipes. (PAPP, 2004). T. albipes has also been implicated in the spread of fungal pod rot disease on cocoa plants. (Tenbrink & Hara, 1992).

    Uses
    In Sri Lanka, T. albipes helps control a pest of coconut, the coconut caterpillar (Opisina arenosella), by feeding on their eggs. (Warner et al, 2002).
    Notes
    T. albipes farm sap-sucking homopterans, protecting them in exchange for a high sugar secretion that many homopterans produce. (Warner & Scheffrahn, 2004). In New Zealand, T. albipes foreli is a regulated pest on plants in the Citrus, Poncirus, and Fortunella genus. Plants in these genus entering New Zealand are subject to visual inspection and approved insecticide treatments. (Biosecurity, 2006)
    Geographical range
    Native range: Indo-Pacific Area (Wetterer, 2002; Warner & Scheffrahn, 2004)
    Known introduced range: United States, Australia, New Zealand, Ghana, Madagascar, India, China, Saudi Arabia, and the West Indies. (Suarezet al, 2005; Deyrup, 2003; Wetterer, 1997; Harris et al. 2004; Wetterer, 2002; Room, 1971; Warner & Scheffrahn, 2004)
    Introduction pathways to new locations
    Nursery trade: T. albipes has been intercepted at ports, particularly in association with cut flowers. (Harris et al. 2004)
    Management information
    Preventative measures: The Pacific Ant Protection Plan is a proposal prepared for the Pacific Plant Protection Organisation and Regional Technical Meeting For Plant Protection. This plan aims to prevent the red imported fire ant and other invasive ant species with economic, environmental and/or social impacts, entering and establishing in or spreading between (or within) countries of the Pacific Region.

    Chemical: T. albipes is difficult to control chemically because chemicals/poisons are not transferred between workers. Baits must be very appetizing to the ants so that large numbers will be individually affected. (Warner & Scheffrahn, 2004). Lindquist (undated) reports that water at a temperature of 49ºC or higher killed greater than 95% of T. albipes.

    In a study of chemical bait efficacy on T. albipes, Imidacloprid, NecDew with DOT, 10ppm Thiamethoxam, and Terro yielded the highest mortality rates for bait traps. In laboratory colonies of T. albipes, NecDew containing 10 ppm of Thiamethoxam was the most effective treatment. Baits that were relatively effective in the laboratory experiment were Imidacloprid in 25%(w/v)sucrose water, NecDew with 10ppm DOT, 10ppm Thiamethoxam in 25%(w/v)sucrose water, and Terro Ant Killer 2. Other baits including residuals, other liquids, gels, one insecticidal dust, and an ultrasonic pest repeller were all unsatisfactory. (Warner & Scheffrahn, 2005). Another study reported that after one day, Talstar had the highest mortality rate, followed by Imidacloprid, and Thiamethoxam. A further study concluded that after 47 days, PJB+Thiamethoxam 10ppm treatment had a 100% mortality rate(MR), eclipsing Imadacloprid instant granules (84%MR) and Imadacloprid Pre-Empt (82%MR). Treatments that didn't vary from controls included Combat Bait Stations, Maxforce ant gel, Termidor, Indoxacarb surface, Demand CS, DeltaDust, XR007, and Whitmire ant bait. (Warner, 2003)

    Biological: Tenbrink & Hara (1992) state that Anoplolepis longipes (long-legged ant) will displace T. albipes and is less likely to spread black pod disease of cocoa; however, A. longipes does tend homopterans. Another biological control option could be parasites, specifically the ones that live in the nests of T. albipes and stunt development of ants in juvenile stages. (Tenbrink & Hara, 1992).

    Physical: Trim trees and shrubs that surround nests to prevent bridging to other vegetation. Do not allow vegetation to touch exterior walls of any edifice. (Warner et al, 2002).

    Sugiura (2008) reports the use of hot water treatment to destroy T. albipes in soil and potted plants. Exposure to hot water at =47°C effectively killed the ant. Temperatures of up to 49°C are non-phytotoxic (Tsang et al., 1995 in Sugiura, 2008), and hot water has no negative environmental effects.

    Nutrition
    T. albipes feeds on plant nectars and honeydews produced by homopterans (aphids, mealybugs, and scale insects). The homopterans are protected by T. albipes in exchange for their nectar secretions. (PAPP, 2004)
    Reproduction
    Reproduction is preformed by intercastes who are inseminated by wingless males from the colony. Winged females (potential queens) and winged males copulate outside the nest after nuptial flight. "New colonies are formed by dealate queens, but those queens are eventually replaced by intercastes. Thus, inbred wingless reproductions allow the enlargement and budding of colonies, often resulting in the formation of huge polydomous (single colonies that occupy more than one nest) containing millions of individuals" (Harris et al. 2004).
    Lifecycle stages
    T. albipes has an unusual colony structure, evolved for large numbers of offspring. This species is one of only a few ant genera that exhibit a remarkable male polymorphism. (i.e. winged and wingless males). There are 3 different female types found in each colony. Queens are females that have wings. Intercastes are wingless females with a spermatheca, making them sexually viable. Workers are wingless females with out aspermatheca. There are also previously winged queens (Dealates), but they are rare or not present in most colonies. (Harris et al. 2004).

    Eggs are laid by queen and protected by workers in the nest. The eggs may be fertilized or unfertilized and are whitish or yellowish .5mm ovals. Larvae appear as soft, legless, pale grups shaped like a crooked-necked squash. Transportation of young in perilous situations is by adults whose sticky saliva allows for young to be attached to their bodies. Immatures are fed and cared for throughout development in the nest by females, and develope faster at warmer temperatures. The juvenile state is a small proportion of T. albipes's lifespan, as workers can live for several years. Female adults tend all stages of juvenile ants, construct and maintain nests, and forage for food. Males exist mainly for reproduction. The queen of the colony is large and winged early in life and lays fertile and unfertile eggs throughout her existence. (Tenbrink & Hara, 2002)

    Principal sources: Tenbrink, V. & A. Hara. 1992. Technomyrmex albipes. Beaumont Reaserach Center.
    Available from:www.extento.hawaii.edu/kbase/crop/Type/technomy.htm
    Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
    Last Modified: Thursday, 9 July 2009


ISSG Landcare Research NBII IUCN University of Auckland