Impact of pre-feeding bacteria and yeast on the subsequent Leishmania population within the gut of female Lu. longipalpis . (A) Leishmania promastigote population estimated within the midgut of Lu. longipalpis after feeding with Pseudozyma sp; Asaia sp. or O. intermedium; 2 - 4 × 107 CFU mL-1. Circles represent individual parasite counts in individual sand fly midguts from 3 independent experiments for each microbial species. *Kruskal-Wallis: P ≤ 0.0001. Mann-Whitney U test: P ≤ 0.007. (B) Percentage of female flies infected with Leishmania. Control group were fed on 7% w/v sucrose before being fed with Leishmania. *Fisher’s Exact Test P ≤ 0.0001.