Tetramorium tsushimae

Emery, 1925

Japanese pavement ant

Tetramorium tsushimae, commonly known as the Japanese pavement , is a small ant to Asia that has become in North America. are approximately 2.5 mm in length. The exhibits both monogyne and polygyne colony structures and is known for its territorial , with colonies competing for high-temperature nesting sites to rear reproductives. It has been extensively used as a laboratory surrogate for the () in and control studies. The species displays notable cadaveric behaviors on animal remains, creating scratched scars, mounds, and soil-covered nests that have forensic implications.

Tetramorium tsushimae by (c) Jonghyun Park, some rights reserved (CC BY), uploaded by Jonghyun Park. Used under a CC-BY license.

Pronunciation

How to pronounce Tetramorium tsushimae: /tɛtrəˈmɔːriəm tsuːˈʃiːmeɪ/

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Identification

Small (2.5 mm), dark-colored with 12-segmented and a distinct node. Distinguished from North Tetramorium by its status and association with human-modified environments. Often confused with Tetramorium caespitum, with which it shares the 'pavement ant' ; separation requires microscopic examination or genetic analysis. In the field, presence in the St. Louis area and adjacent Illinois suggests T. tsushimae over T. caespitum in that region.

Images

Appearance

approximately 2.5 mm in length. Newly emerged workers have light that darken to black with age. appear , changing to murky -brown when stressed. Winged reproductives () present in colonies.

Habitat

to Japan, where it occupies diverse . found in urban and suburban environments, particularly in pavement and soil adjacent to human structures. Laboratory colonies maintained at 25°C and 70% in artificial nests with plaster substrate. In Japan, colonies prefer high-temperature nesting sites (27.5–30°C) for rearing reproductives, with most reproductive-rearing sites located along borders between neighboring territories.

Distribution

to Asia (Japan). in North America, with established in the conterminous 48 United States, particularly around the St. Louis, Missouri area and adjacent Illinois. Collected in Tsukuba City, Japan (36°05′31″N, 140°04′35″E) for research purposes.

Diet

, feeding on both and animal materials. In laboratory settings accepts -pet food jelly, -based (fish and insect), sugars (powdered sugar, condensed milk), and water. Field diet inferred from foraging typical of the .

Life Cycle

with , larval, pupal, and stages. In laboratory colonies at 25°C, new emerge after approximately 18 days. Colonies can be monogyne (single ) or polygyne (multiple queens). Reproductive production concentrated in colonies with larger territories, with growth rates of reproductives positively correlated with rearing temperature.

Behavior

Territorial with colonies competing for high-temperature nesting sites. forage between nest and food sources through established routes. Exhibits cadaveric attendance behaviors on animal remains, including producing scratched scars, mounds, and soil-covered nests around carcasses. Workers remove dead individuals from colonies. Cold anesthesia (ice) can be used for handling without negative effects.

Ecological Role

forager and scavenger. In its range, contributes to through decomposition activities. potential in North America due to flexible colony structure (mono- and polygyne forms) and territorial expansion capabilities. Used as surrogate in laboratory studies for developing control agents against invasive fire .

Human Relevance

pest in North urban areas. Used extensively as a laboratory model for testing control agents, particularly for post-establishment control of the (). Forensic relevance due to distinctive cadaveric behaviors that can alter decomposition scenes and create postmortem artifacts on animal remains. May cause confusion in death scene interpretation due to soil mounding and scarification of remains.

Similar Taxa

Tetramorium caespitumShares 'pavement ' and similar size and general appearance; historically confused due to morphological similarity and overlapping common names. Separation requires microscopic examination of specific morphological characters or genetic analysis.
Tetramorium immigransAnother pavement in North America with similar and preferences; part of the taxonomically complex T. caespitum species group that has been split into multiple cryptic species.

More Details

Laboratory Model Organism

Widely used as a surrogate for in colony-level oral tests due to similar colony structure and manageable laboratory rearing requirements. Has enabled testing of fipronil, pyriproxyfen, and etoxazole for control efficacy.

Forensic Significance

Documented to produce distinctive postmortem artifacts on rabbit cadavers including scratched scars, soil mounds, and covered nests. These behaviors can interfere with normal -driven decomposition and may be mistaken for human activity at death scenes.

Thermal Ecology

Unusual among temperate in strong preference for high-temperature nesting zones (27.5–30°C) for rearing reproductives. This drives territorial expansion and multiple nest site formation as colonies compete for limited warm microhabitats.