BUMBLEBEES (BOMBIDAE) ALONG POLLUTION GRADIENT - HEAVY METAL ACCUMULATION, SPECIES DIVERSITY, AND NOSEMA BOMBI INFECTION LEVEL

Pollinator crisis (Kearns et al. 1998) and its possible causes has become a world-wide issue during the last two decades. Although pollution is among the possible causes of the widely observed pollinator loss, it is still poorly investigated and no studies are known, so far to test the effects of heavy metal contamination in bumblebees (Bombidae) - the second most important group of managed pollinators after honey bees (Apis mellifera Linneaus). We have tested heavy metal (Pb, Cd, and Zn) accumulation, species diversity and parasite load (focusing on the common Nosema bombi Fantham and Porter, Microsporidia: Nosematidae) in bumblebees. For this purpose, we have chosen three heavy metal gradients (Guryevsk, Belovo and Olkusz) and two additional control sites (Kouznetskiy Alatau and Gornaya Shoria). All gradients were approximately 20 km long, starting in close proximity (1.3 km or less) of an active zinc or metal smelter, and each consisting of 5 sites located on semi-natural or degraded meadows in various distance from the smelter. On each site min. 50 bumblebees were caught by sweep nets, each individual identified to species level and next, its abdomen homogenized and used for assessment of N. bombi infestation. Heavy metal levels in soil of the tested gradients varied between (Pb: 13.6-814.2 mg kg super(-1), Cd: 0.14-20.3 mg kg super(-1), Zn: 67.0-889.3 mg kg super(-1)) Bumblebees accumulated Pb and Cd (Pb: 0.21-3.3 mg kg super(-1), Cd: 0.002-0.069 mg kg super(-1)) in their bodies. The content of these metals in bumblebee bodies correlated with their content in soil (Pb: P