Bumblebees are significant pollinators for both wild plants and economically important crops. Due to the worldwide decrease in pollinators, it is crucial to monitor the prevalence and distribution of bumblebee pathogens. Field-caught bumblebee workers and males were examined for the presence of three pathogens during the summer months of the years 2015-2020 (Bombus terrestris/lucorum) and 2015-2017 (Bombus lapidarius). The greatest prevalence was in the case of Crithidia bombi, where significantly more workers (57%) of B. terrestris/lucorum were infected than males (41%). Infection was also confirmed in 37% of B. lapidarius workers. The average prevalence was very similar in the case of Nosema bombi in workers (25%) and males (22%) of B. terrestris/lucorum. In the case of B. lapidarius, 17% of the workers were infected. The lowest number of infected individuals was for Apicystis bombi and the prevalence of infection was significantly higher for males (22%) than workers (8%) of B. terrestris/lucorum. Only 3% of workers and 4% of males of B. terrestris/lucorum were simultaneously infected with three types of pathogens, but no worker was infected with only a combination of N. bombi and A. bombi. The greatest prevalence of C. bombi was found in urban or woodland areas.
Keywords: Apicystis bombi; Crithida bombi; Nosema bombi; bumblebees; pathogen.