Rapid range expansion in Lasius neglectus (Hymenoptera, Formicidae) - an Asian invader swamps Europe

After its first observation in Europe in 1974, Lasius neglectus Van Loon, B oomsma & Andrasfalvy 1990 has performed a rapid range expansion throughout the entire Mediterranean area and has reached Central Europe. The present r ange is delimited by 1 degrees E and 75 degrees E and by 36 degrees N and 4 9 degrees N with 38 sites known. Regarding colony structure, mating, mode o f distribution, local dominance, pest status, and impact on local ant fauna s, neglectus is comparable to Linepithema hll,humile (Mayr 1868). L, neglec tus, however, can establish permanent colonies in regions with mean January temperatures of -5 degreesC. Climatic barriers ending the northern expansi on of Linepithema and preventing its long-term outdoor persistence in Centr al Europe and S Scandinavia will not stop neglectus that has the potency to develop into a most important pest species. Morphology. genetics, and zoog eography suggest a very recent separation of neglectus from Lasius turcicus Santschi 1921 with a most probable radiation centre in Asia Minor, The beh avioural change from normal aerial mating to exclusively intranidal mating is considered as deciding step leading to complete reproductive isolation f rom turcicus. The obvious absence of turcicus from huge parts of neglectus' range is a further argument against considering the two as expression of i ntraspecific polymorphism. The loss of flight behaviour in queens is still nor accompanied by significant morphological changes: wing load and develop ment of flight muscles or fat tissue are comparable to well-flying and clau strally founding Lasius species.