Effect of bacterial culture supernatants and replete medium on the development of metacyclic promastigotes in P. duboscqi. Flies were artificially fed through a membrane on mouse blood seeded with 4×106 / ml LmRy promastigotes. Beginning on day 5 p.i., flies were treated or not with P/S and/or culture supernatant from Ochrobactrum anthropi and/or Rahnella aquatilis, in the sugar meal (A & B), or fed on M199 or Grace’s Insect Medium supplemented with BME, folate, hemin, and adenosine with or without P/S (C&D). Values shown are numbers of metacyclic promastigote per individual flies with geometric means ± 95% CI on days 13-14 p.i. Data shown in A,B, &D are each representative of two independent experiments; C is representative of three independent experiments.