Alteration of Microflora of the Facultative Parasitic Nematode Pristionchus entomophagus and its Potential Application as a Biological Control Agent

Amy M. Michaud, University of Maine


Pristionchus entomophagus is a microbivorous, facultative, parasitic nematode commonly found in soil and decaying organic matter in North America and Europe. This nematode can form an alternative juvenile life stage capable of infecting an insect host. The microflora of P. entomophagus is highly variable and may contribute to insect host mortality. Pristionchus entomophagus is not associated with specific bacterial species, and its microflora may possibly vary with habitat and/or hosts. The goal of this project was to develop protocols to transfer labeled bacteria to P. entomophagus, and then assess transfer of the labeled bacteria to an insect host via exposure to altered nematodes. Successful inoculation of the nematodes and transfer to the insect would provide a method to enhance virulence of P. entomophagus for use against M. rubra and other pest insects. I successfully developed a protocol to alter the microflora of P. entomophagus nematodes, but was unable to confirm transfer of the target bacteria by nematodes to Galleria mellonella larvae. The internal microflora of most adult nematodes was altered and juveniles exposed to the labeled bacteria were seen to carry it on the external surface of their cuticle. Juveniles are the infective stage, and without internal haborage, they may be poor vectors of the target bacteria. Another challenge in developing P. entomophagus as a biological control agent is potential nematicidal activity of entomopathogenic bacteria. Overall, the results of this study are promising and provide the initial steps towards the development of P. entomophagus with enhanced virulence as a biological control agent.