Pollinator crisis (Kearns et al. 1998) and its possible causes has become a worldwide 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–1, Cd: 0.14–20.3 mg kg–1, Zn: 67.0–889.3 mg kg–1) Bumblebees accumulated Pb and Cd (Pb: 0.21–3.3 mg kg–1, Cd: 0.002–0.069 mg kg–1) in their bodies. The content of these metals in bumblebee bodies correlated with their content in soil (Pb: P <0.01, Cd: P = 0.002). However, no correlation was found between the Zn contents in bumblebees (Zn: 74.7–81.9 mg kg–1) and the soil. We have also found that the metal contents in soil or in the bodies of bumblebees caused no changes in species diversity or dominance on polluted sites, irrespective of type and the level of contamination. The variation of Shannon diversity (H’), as well as Simpson’s diversity (D) were similar in all studied sites and ranged from 0.543 to 0.81 and from 0.152 to 0.484 respectively. The proportion of infected individuals was generally not higher than 0.29 and did not differ significantly among the studied sites. Incidentally, based on variation in the small subunit ribosomal RNA (SSU-rRNA) gene, we have found a new strain of Nosema bombi in the Kouznetskiy Alatau and Gornaya Shoria (West Siberia, Kemerovo Region) samples. The new small subunit RNA sequence in the new strain of N. bombi was named N. bombi WS2 (West Siberia) SSU rRNA. Based on the obtained results we conclude, that bumblebees can withstand or even successfully deal with heavy metal contamination at certain levels.
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