Distribution and dynamics of the Argentine ant Linepithema (Iridomyrmex) humile (Mayr) in relation to vegetation, soil conditions, topography and native competitor ants in Portugal

摘要: The overall distribution of Linepithema humile, introduced about a hundred years ago and now widespread in western southern Portugal, has not notably changed the last forty years. ant is particularly common sand clay loam soils but, inexplicably despite otherwise favourable conditions, largely absent adjoining easterly mostly sandy associated with metamorphic rocks. In these circumstances there was striking change transition areas from exclusive dominance by L. humile to competing native species, Crematogaster scutellaris Pheidole pallidula, which directly soil type. site particular type (Vt) comprising patches colonized either or ants, former occurred where greater content. oak planted Vt present cultivated grazed ground but replaced C. when well established scrub vegetation. There intense fighting at line one place uniform tree vegetation that supported large populations dominants on opposite sides transition. Here, had spread 30 m per year between 1993 1996 compared an estimated 800 first 60 after introduction. It concluded dominant P. pallidula their favoured plantation habitats, T. nigerrimum hispanicum some arable pasture habitats can delay prevent conditions also suit it. Although most valley floors, its presence abundance were significantly related it sometimes abundant tops hillsides seasonally water-deficient areas. Its association built-up strikingly displayed town inimical metamorphic-based uncolonized immediately vegetationally agricultural land. direct indirect effects are analysed discussed. Three free human interference – dunes trees bare areas, similarly patchily vegetated rocky river gorge eroded arete may exemplify natural exploited South America.