Submitted to: National Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2013
Publication Date: N/A
Technical Abstract: A Salmonella Montevideo strain that is resistant to ampicillin and kanamycin and that expresses the green fluorescent protein (S Montevideo-GFP) was utilized to inoculate sterile and non-sterile cattle manure (1 x 105 CFU/gram manure) onto which sterilized horn fly embryos were placed and held for emergence. The mean percentage of pupae recovered across all substrates was 80.55% indicating that S. Montevideo does not affect survival of larvae to the pupal stage. Salmonella was not recovered from any pupae that developed on non-sterilized manure, regardless of whether or not it had been inoculated with Salmonella. The only substrate from which S. Montevideo-GFP was recovered, was in pupae that had developed in sterilized, inoculated manure. These results suggest that the resident microbial community may outcompete Salmonella in the substrate and that larvae may readily ingest Salmonella, but the bacteria is more effectively lysed and cleared since the larvae are provided with a full microbial complement as a nutrient source and would not experience nutritional stress that could affect immune responsiveness to microbes. Frequency with which adults eclosed from pupae was also not significantly affected by presence of Salmonella. Adults that emerged were subsequently rinsed in PBS to assess surface contamination and then macerated to evaluate adult infection. Of the total adults evaluated, S. Montevideo-GFP was recovered in surface washes from only three individuals and in very disparate quantities. In an effort to describe the final destination of Salmonella upon adult eclosion, prevalence of viable S. Montevideo-GFP in pupal cases was assessed from individuals that developed in inoculated substrates (non-sterilized and sterilized). No S. Montevideo-GFP was recovered in pupal cases that originated from non-sterilized substrate. Further studies will evaluate quantities of recoverable Salmonella over the course of horn fly pupal metamorphosis to more clearly describe its density during this period, prior to adult eclosion.