Comparison of the movement of Escherichia coli O157:H7 and Salmonella enterica, to lettuce by the blow fly, Phormia regina (Meigen) and house fly, Musca domestica

Filth flies have been implicated in dispersal of human disease pathogens; however, fly transmission parameters of human pathogens to plants are largely unknown.  Filth flies are a possible vehicle for contamination of edible plants.  The ability of Phormia regina (Black blow flies) and Musca domestica (House flies) to acquire bacteria and subsequently release the bacteria on to lettuce leaves was compared.  Adult P. regina and M. domestica 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 differentially moved the S. enterica and E. coli O157:H7 to lettuce plants.