Fig 2.

Bacterial colonization of the medfly during ontogeny, tracked by fluorescent in situ hybridization and confocal microscopy using a Bacteria-directed Cy3-EUB338 oligonucleotide probe applied on laboratory-raised flies and DAPI or Sybr green nucleic acid stain. (A) Egg. Microcolonies on the surface of a medfly egg appear as red dots on the red fluorescent background of the egg chorion. (B) Larval gut. Bacterial growth appears as discontinuous patches along the larval gut. Red, bacterial masses; green, fly gut cell nuclei. (Inset) Within these patches, the bacterial density is high. Red, bacterial cells/microcolonies; green, bacterial cells and fly gut cell nuclei. (C) Adult medfly midgut 1 day after eclosion. Red, bacterial masses. (D) Midgut and hindgut of a laboratory-reared female adult medfly 30 days after eclosion. Continuous bacterial colonization is seen in the midgut as well as in the hindgut. Red, bacterial masses. The line encompasses the hindgut. (E to G) Midguts of field-captured wild specimens showing various extents of gut colonization. (E) Female; (F and G) males. Red, bacterial masses; blue or green, gut cells.