In non-teneral flies, RNA knockdown of either tsetse EP protein or Relish, the transcriptional activator of antimicrobial peptide (AMP) genes via the immunodeficiency (IMD) pathway, led to increased midgut infection rates with T. brucei [13, 36], suggesting that tsetse EP protein and/or AMPs could be key players in the immunity to sequential infection observed here. This evidence concerns the gene ADSL and infection.