Fig. 2

Citrobacter sp. isolation and identification. a Colony characteristics on brain heart infusion (BHI) agar plates for bacteria that were isolated from the gut of SS and RS flies. b Phylogenetic relationships of the symbiotic CF-BD strain. The red star indicates the trichlorphon-degrading CF-BD strain. A maximum likelihood phylogeny inferred from 1521 aligned nucleotide sites in 16S rDNA gene sequences is presented with bootstrap values. The accession numbers of the 16S rDNA sequences for each bacterium are listed in the square brackets. c The rod-shaped CF-BD strain has blunt, round ends and a red color, as identified by Gram staining. d, e The midgut organization of B. dorsalis and CF-BD localization in the midgut of RS flies. Red signals indicate CF-BD symbionts, whereas blue signals show host insect nuclei. Abbreviations: M, midgut; Mt, Malpighian tubules; H, hindgut; Rp, rectal pads