Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Food Technology

Committee Chair/Advisor

Dr. Paul Dawson

Committee Member

Dr. Julie K Northcutt

Committee Member

Dr. Johnny McGregor

Committee Member

Dr. Eric Benson


Two separate sets of experiments were conducted to determine the transfer of bacteria by flies. An Escherichia coli ampicillin-resistant strain with a fluorescent gene was used during the experiments. The first set of experiments were divided into two trials to measure the transfer of E. coli by fruit flies to apple slices and bologna during short term exposure. Short time exposure (1, 5 and 15 min) of flies to inoculated apple slices were tested in the first trial to determine the transfer of E. coli to flies. No difference (P>0.05) in the number of bacteria transferred to flies were found associated with these exposure times. In the second trial, the transfer of E. coli from inoculated apple or bologna slices (5 min exposure) to un-inoculated slices (1, 5 and 15 min exposure) were evaluated. More bacteria were transferred to bologna after 1 and 5 min exposure times compared to transfer to apples, while the number of cells transferred did not differ for bologna and apples after 15 min exposure. The percentage of E. coli transferred from inoculated food to flies was low (relatively high (>50%). This study found that flies can pick up and transfer bacteria to food in short exposure times.

Filth flies, especially house flies, can harbor and ultimately distribute human pathogens to food and food contact surfaces. To determine the potential of flying insects collected from poultry grow out houses to carry Salmonella and Campylobacter, a total of 2164 flies were caught on poultry farms located in the Upstate, Middle, and Coastal regions of South Carolina and segregated based on fly family type. Capture flying insects included house flies in the family Muscidae inside the poultry house [in-HF] (N = 289), house flies just outside the poultry house [out-HF] (N =1023), and house flies 100 meters from the poultry houses [100m-HF] (N = 547). Other flying insects included wasps in the family Vespidae species (spp.) captured just outside the poultry house [out-Vespidae] (N = 71), Vespids spp. 100 meters from the poultry house [100m-Vespids] (N = 126), flesh flies in the family Sarcophagidae just outside the poultry house [out-Sarcophagids] (N = 13), and flesh flies 100 meters from the poultry house [100m-Sarcophagids] (N = 9), blow flies in the family Calliphoridae 100 meters from the poultry house (100m-Calliphorids), darling beetles in the family Tenebrionidae just outside the poultry house [out-DB] (N = 30), and darling beetles 100 meters from the poultry house [100m-DB] (N = 56). Populations of Campylobacter spp., Salmonella spp., and total aerobic microorganisms (APC) were recovered from the flies as well as the number of Salmonella spp. and Campylobacter spp. positive flies at a 100 m distance from the farms. Along with fly groups, chicken feces in the houses [CF] from three farms, cow manure around farm 1 and farm 2, and dog feces around farm 1 were also sampled. While no Campylobacter jejuni was detected from any of the samples, including fly groups, chicken feces, cow manures, and dog feces, Campylobacter coli positive samples were detected in the cow manure samples in both replications, 100m-Calliphoridae, out-HF and 100m-DB in one out two replications on farm 2. Moreover, positive Serogroup B Salmonella spp. were determined in the groups in-CF, in-HF, and out-HF on farm 2 and positive Serogroup C Salmonella spp. were determined in the groups of in-CF, out-HF, and 100m-HF on farm 3. Data demonstrates that house flies may be a vector in the transmission of Salmonella spp. from poultry farms.



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