Ingestion of Pseudomonas fluorescens Pf-5 by Drosophila melanogaster causes larval immune response dependent on bacterial media type. Kristin L. Latham, Amy Nicholson, Jenna Schneider, Elizabeth Mason. Biology, Western Oregon Univ, Monmouth, OR.

   While immune system response to pathogens has been well-studied in Drosophila adults, little is known about response to bacterial exposure during early larval stages. We have exposed first- and second-instar larvae to Pesudomonas fluorescens strain Pf-5 by a non-invasive feeding procedure. Larvae fed P. fluorescens show dose-dependent differences in time to metamorphosis and survival. Interestingly, larvae fed Pf-5 cultured in different types of bacterial media show distinct differences in growth rate and immune phenotype, suggesting that this bacterial strain produces metabolites that vary with culture media components, leading to varied larval immune response. We are currently investigating more deeply whether the larval response is cellular and/or humoral. These data suggest that immune response in Drosophila larvae elicited by Pf-5 bacteria is dependent not just on bacterial dose but also on which bacterial metabolites are present.