A peaceful zone bordering two Argentine ant (Linepithema humile) supercolonies
- 289 Downloads
In invasion areas, the Argentine ant (Linepithema humile) forms huge supercolonies with free exchange of individuals among nests. Two continental supercolonies on the French mediterranean coast, the Main European supercolony and the Corsican supercolony, are known to contain workers showing moderate to high levels of inter-supercolony aggression. We performed chemical and behavioral assays using workers from eight coastal sites in southeastern France covering a geographical zone that includes nests of the two supercolonies, to determine the nature of worker interactions in a supercolony boundary zone. We examined how the chemical and behavioral clines vary across the borders of the Main and Corsican supercolonies. Our results on Giens peninsula and Porquerolles island populations bordering the Main supercolony reveal the existence of a peaceful border zone with no aggression between workers of the Main supercolony and the Corsican supercolony. The chemical results, however, exhibited qualitative similarity to those observed in the Corsican supercolony and revealed both quantitative and qualitative chemical differences from those observed in the Main supercolony. These peaceful populations may result from fusion and/or genetic crosses between the two supercolonies, and we hypothesize that such peaceful border zones are instrumental in the evolution of supercolonies.
KeywordsLinepithema humile Cuticular hydrocarbons Fusion Territory border Aggressive behavior, unicoloniality
This project was supported by the Provence-Alpes-Côte d’Azur Region. We thank Stéphane Greff for their help with the GC–MS. Our thanks to M. Sweetko for English language revision.
- Chopard L (1921) La fourmi d’Argentine Iridomyrmex humilis var. Arrogans Santschi dans le midi de la France. Annales Epiphyt 7:237–265Google Scholar
- Gordon DM (1989) Ants distinguish neighbors from strangers. Oecologia 81:198–200Google Scholar
- Marchal P (1917) La fourmi d’Argentine (Iridomyrmex humilis Mayr). Bull Soc Vulg Zool Agric Bordeaux 16:23–26Google Scholar
- Veyret M (1961) La fourmi d’Argentine dans la région toulonnaise. Ann Soc Sci Nat Arch Toulon 132:5Google Scholar