Movement of enteric bacteria by Phormia regina (Meigen) to plants

The ability of Phormia regina (Black blow flies) to acquire bacteria and subsequently release the bacteria on to lettuce leaves was assessed.  Blow flies have been implicated in dispersal of human disease organisms to artificial surfaces and prepared foods.  However fly transmission of human pathogens to plants is largely unknown.  Filth flies are a possible conduit for  bacterial contamination of leafy greens.  P. regina adults were exposed to E. coli O157:H7 or S. enterica inoculated manure for one hour then allowed overnight access to lettuce plants.  The plants and flies were then tested for presence of bacteria by standard microbiological methods.  PCR was used to confirm the identity of putative positive colonies on selective media.   Flies moved the S. enterica and E. coli O157:H7 to lettuce plants at low levels.