(A) Subdued knockout flies display susceptibility to Serratia infection. Wild-type (WT) and knockout (KO) flies were fed on a Db11/sucrose solution and their survival monitored for 192 hr post-infection. Two independently generated KO strains, KO2 and KO11, were used. WT flies lived significantly longer compared to KO2 and KO11 (n = 4, p<0.001, two-way ANOVA). (B) KO flies accumulate higher titers of bacteria in the whole animal. 20 whole flies were homogenized 48 hr post-infection. Serially diluted homogenates were plated on agar and inspected for Db11 colony forming units (CFU). Significantly more bacteria were recovered from the KO flies (n = 7, Student’s t-test, p<0.01). (C) KO flies do not consume more food than WT flies. Four fly guts were dissected and homogenized from vials of 20 flies fed with Db11/sucrose solution containing 0.5% wt/vol erioglaucine disodium salt (FDC Blue #1) 72 hr post-infection. The amount of food eaten by the flies was estimated by measuring absorbance of the dye. KO flies tended to consume significantly less food than WT flies (n = 5, p<0.01, repeated measures one-way ANOVA and Tukey’s multiple comparison test). No significant difference was observed between the KO strains. (D) The homogenate obtained from experiments described in (C) was inspected for Db11 colony forming units (CFU). Significantly higher amounts of bacteria were recovered from KO compared to WT fly guts (n = 6, p<0.05, repeated measures one-way ANOVA and Tukey’s multiple comparison test). No significant difference was observed between KO strains.