Bumblebee (Bombus Latreille, 1802) distribution in high mountains and global warming

The planet’s global warming is seriously menacing the survival of a lot of species that are particularly demanding ecologically. Bumblebees include a great number of species with a boreal and/or high mountain, and often disjoint distribution, that appear particularly sensitive to climatic variations. Also in Italy the alticolous species could be exposed in future decades to a progressive reduction of their distribution areas. Therefore it seems convenient to check the presence of the most important species of the Alps and Apennines based on recent observations, even if necessarily limited to a small number of valleys or mountain massifs. In particular we took into consideration Bombus monticola and B. mucidus, present in cacuminal zones of the Apennines and in the Alps, and B. alpinus and B. mendax living in the higher zones of the Alps. B. monticola, represented in the central Apennines by the subspecies B. m. konradini, appeared rare, poorly spread and limited to elevations above 2000 m, while the subspecies B. m. hypsophilus was abundant in the Alps starting from 1450 m; on the contrary B. mucidus was observed in the Apennines at relatively low elevations too, much more frequently than in the Alps. B. alpinus was found exclusively in few Piedmontese localities above 2100 m, where it was poorly numerous, while B. mendax, more abundant and diffused than the previous one, was observed starting from 2000 m in the central eastern Alps and from 2200 m in the western Alps. A rise in temperature represents a serious danger for the Apenninic populations of B. monticola and B. mucidus that risk the extinction for the lack of suitable areas for their survival, while the Alpine species do not seem endangered. The situation of B. alpinus and B. mendax would seem less compromised, even if a rising of the lower altitude limit of their distribution area would mean a drastic reduction of it and the consequent formation of small isolated populations.