Potential biocontrol of Erwinia tracheiphila by Pseudomonas fluorescens via cucumber beetle gut interactions

The causal agent of bacterial wilt of cucurbits, Erwinia tracheiphila (Et), is transmitted by striped cucumber beetle, Acalymma vittatum.  Managing this disease and the beetles causes increase in insecticide inputs in the Northeastern United States.  Pseudomonas fluorescens (Pf) is a common soil bacterium that has been used to control the causal agent of fire blight, Erwinia amylovora, by competitive exclusion. We aim to determine if Pf can competitively exclude Et via in vitro culturing assays and in vivo laboratory experiments.  To test for potential inhibition, Et and Pf were cultured and monitored for bacterial zones of inhibition.  Our preliminary data from the in vitro experiments support the hypothesis that Pf will inhibit Et.  The next step is to visualize Pf and Et in the beetle gut to determine inhibition potential.  This will be done by fluorescent in situ hybridization of beetle guts after bacterial inoculation.  Data collected from the in vivo experiments will provide evidence as to the potential of Pf as a biocontrol for Et via beetle gut interactions.