Figure 2. Symbiont status mediates tsetse's ability to survive challenge with E. coli K12.

(A) The effect of symbiont status on the survival of tsetse following systemic and per os challenge with E. coli K12. Mature adult Gmm^Apo flies were significantly more susceptible to challenge with 10³ CFU of E. coli than were age-matched Gmm^WT (bottom and top panels, p < 0.001) and Gmm^Wgm− flies (bottom and middle panels, p < 0.001). Both Gmm^WT and Gmm^Apo flies survived per os challenge with E. coli. Infection experiments were performed in triplicate, using 25 flies per replicate. (B) Average number (±SEM) of recE. coli_pIL per tsetse cohort over time (n=3 individuals per cohort per time point) following systemic and per os challenge with 10³ CFU of bacteria. Values shown in grey represent lethal infections. By 8 dpc, not enough E. coli-injected Gmm^Apo flies remained to quantify bacterial density.