Tropical arboreal ant mosaics: innate attraction and imprinting determine nest site selection in dominant ants

摘要

Two dominant African arboreal ants of economic importance, Tetramorium aculeatum (Myrmicinae) and Oecophylla longinoda (Formicinae) were compared. The two species differed in terms of innate attraction to nesting site plants, their hierarchies of attractiveness being nearly inverse. Winged females and workers were confronted with choice tests using 4 plant species. By using winged females and workers originating from one of the plants to be tested, the existence of a familiarisation process which can supersede innate attraction in both species was shown. The same effect was recorded in neonatal workers bred in the laboratory in contact with a tested plant for 25 days after emergence, while mature workers could not be conditioned. There is, therefore, early learning, with a sensitive period after which the influence of the environment ceases, suggesting that this is a true imprinting process. Choice tests using neonates produced from larvae and pupae bred in the laboratory in contact with the leaves of each tested plant permitted the demonstration of the existence of pre-imaginal learning. Nest site selection therefore depends on innate selective attraction and on environmental factors whose effect begins at the larval stage. There is, therefore,the potential to "control" imprinting, allowing one ant species to be favoured to the detriment of others in monospecific tree crop plantations.