Parasite escape by recombination
Regula Schmid-Hempel, Regula Schmid-Hempel , Corinne Schnellmann
ETH Zurich; ETH Zurich ; ETH Zurich
The trypanosome Crithidia bombi is a common pathogen of bumblebees. In experiments with colonies of Bombus terrestris, we investigated how genotypes of the parasite stay or change in the infecting population of a colony. The protocol mimicked the natural pathway of infections by inoculating founding queens with two different strains each. Tracing the genotypes in the colonies established by these queens revealed that the original strains quickly disappeared and were replaced by recombinations of these parental genotypes. In addition, the major generator of novelty was the queen herself. This combines with the result that colonies vary in their susceptibility or tendency to allow for new strains, and shows that epidemics of C. bombi are heavily affected by within-colony processes.