Crithidia bombi

Crithidia bombi is a parasitic protist from the order Trypanosomatida. It is the most prevalent parasite of bumblebees.

Ecology
Crithidia bombi is an important parasite of various bumblebee species, including common species like Bombus terrestris, Bombus muscorum, and Bombus hortorum. The parasites negatively impact reproductive fitness of Bombus queens, as they affect their ovarian development as well as early colony establishment after the queens emerge from hibernation.