Interaction of bumblebee gut microbiota with Crithidia bombi

Gut microbiota confers protection against the trypanosomatid parasite Crithidia bombi in bumblebees. The aim of the study was to understand better the mechanisms by which gut microorganisms protect the host. Workers of Bombus terrestris were reared in semi-sterilised conditions to reduce their microbiota. The gut microbial community was restored in some individuals by feeding them with microbiota supplements. Later, they were exposed to an infectious dose of Crithidia bombi. Immune gene expression and gut microbiota composition was characterised to test if the microbiota protect the host through stimulation of its immune response, or by competing for resources with the parasite inside the gut.