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Seasonal spatial dynamics and causes of nest movement in colonies of the invasive Argentine ant ( Linepithema humile )
Author(s) -
HELLER NICOLE E.,
GORDON DEBORAH M.
Publication year - 2006
Publication title -
ecological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.865
H-Index - 81
eISSN - 1365-2311
pISSN - 0307-6946
DOI - 10.1111/j.1365-2311.2006.00806.x
Subject(s) - linepithema , argentine ant , nest (protein structural motif) , biology , ecology , microclimate , hymenoptera , biochemistry
1. Colony organisation and movement behaviour of the Argentine ant ( Linepithema humile ) was studied over 3 years in field populations in California and in captive colonies in the laboratory. This invasive species is highly polydomous and unicolonial; colonies consist of expansive and fluid networks of nests and trails. The spatial and temporal organisation of colonies may contribute to ecological dominance. 2. Argentine ant nests and inter‐nest trails shift in size, abundance, and location, so that colony networks are spatially contracted in the winter and expanded spring to autumn. Colonies occupy permanent sites; ants migrated to and from the same winter nest locations year after year, and occupied 30% of the same nests repeatedly during seasonal migrations. 3. Nests were moved on average 2–3 m. Forty‐two per cent were occupied less than 1 month, 4% the entire study, and the other 54% lasted 3.9 ± 2.3 months (mean ± SD). 4. Nests were located within 2–4 m of woody plants, in warm sites in the winter and cool sites in the summer. Both humidity and food availability influenced nest‐site choice in laboratory colonies. However, when faced with a trade‐off between factors, the ants chose humid nest boxes over nest boxes near food, and ants moved nests only in response to changes in humidity and not distance to food. 5. The results indicate that L. humile colonies are seasonally polydomous, and that nest movements are driven by changes in microclimate. Colony organisation maintains high local density and increases food supply, which may improve the competitive ability of L. humile colonies and reduce opportunities for species coexistence.