Linepithema

Mayr, 1866

Species Guides

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Linepithema is a of small ants in the Dolichoderinae, comprising approximately 20 described . The genus is native to the Neotropics, ranging from northern Mexico through the Caribbean to northern Argentina, with species occurring from sea level to 4,000 meters elevation in the Andes. Two species, L. humile (the ) and L. iniquum, have been introduced globally through human activity. L. humile is among the most successful species worldwide, forming massive supercolonies in Mediterranean-type climates.

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Pronunciation

How to pronounce Linepithema: /ˌlaɪnɛpɪˈθiːmə/

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Identification

Linepithema are small ants distinguished within Dolichoderinae by their combination of small size, lack of a sting, and presence of a single petiolar node. The can be separated from related dolichoderine genera by morphological characters including mandibular and mesosomal structure. Species-level identification requires examination of male genitalia and other subtle morphological features.

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Habitat

Native occur in diverse Neotropical from lowland tropical forests to high-elevation Andean grasslands, up to 4,000 meters above sea level. Introduced of L. humile thrive in Mediterranean climates, typically associated with disturbed habitats resulting from human commercial activities.

Distribution

Native distribution spans northern Mexico east to the Caribbean and south to northern Argentina. Two have established ranges: L. humile occurs on five continents in Mediterranean-type climates, and L. iniquum has been spread globally by human activities.

Life Cycle

Colonies are polydomous, with members residing in multiple interconnected nests rather than a single central location. Nest network expansion from initial single nests occurs rapidly over 5–10 days. Some queens and migrate to expansion sites, though most expansion sites contain only .

Behavior

Colonies exhibit polydomy with interconnected trail systems allowing free exchange of between nests. Expansion favors food-rich over water-rich areas, but colony-level satiation limits total saturation. of L. humile display unicolonial organization, with extensive networks of interrelated colonies lacking intraspecific aggression.

Ecological Role

Native function as foragers in Neotropical . L. humile forms supercolonies that displace native faunas, alter , disrupt ant-vertebrate interactions, and modify ant-plant relationships. The species tends honeydew-producing hemipterans, potentially affecting plant growth and agricultural production.

Human Relevance

L. humile is designated as a tramp ant due to its exceptional ability to spread and establish in new areas. It is considered a significant pest species, causing agricultural damage through mutualisms with crop-damaging hemipterans, disrupting native , and occasionally becoming a household pest. Management costs in New Zealand alone are estimated at NZ$60 million annually. Control relies primarily on chemical sprays and toxic baits; Xstinguish™ and Exterm-an-® have shown highest mortality rates in laboratory studies.

Similar Taxa

  • IridomyrmexBoth are dolichoderine ants with small and lack of sting; distinguished by mandibular structure and male
  • TapinomaSimilar small size and general habitus; separated by petiolar node structure and chemical defense compounds

More Details

Bacterial associates

L. humile maintains a core gut microbiome of nine bacterial including Lactobacillus and Gluconobacter. Bacterial diversity declines along invasion while this core is retained. treatments can increase bacterial diversity and, in some cases, survival or aggressiveness.

Viral pathogens

L. humile two actively replicating viruses: Deformed wing virus (DWV), known from honey bees, and virus 1 (LHUV-1), a newly described virus related to DWV. The may serve as a for these , though their effects on remain unknown.

Genomic resources

Phylogenomic studies using ultraconserved elements have substantially revised understanding of dolichoderine evolution, more than doubling sampling for the and revealing novel relationships among .

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