In the present study, we studied ecology of three species of mollusc-parasitic nematodes: Phasmarhabditis bohemica, P. bonaquaense and P. apuliae. We demonstrate that these facultative parasitic nematodes can grow in polyxenic and monoxenic combinations with bacteria Acinetobacter sp., Flavobacterium sp. and Pseudomonas sp. but some combinations do not support nematode reproduction. Bacteria Pseudomonas sp. did not support the growth of P. bonaquaense while P. apuliae grows only in combination with Flavobacterium sp. Composition of the culturing media apparently influenced the development time. Animal tissue-based substrates enabled slightly faster development than others. Similarly, also monoxenization of nematodes shortens the time to emergence of new dauer juveniles. Yields of dauer juveniles were usually higher in animal tissues than in other substrates. Generally, the most productive species was P. bohemica and the highest quality of dauer juveniles, expressed by their body size and lipid content, was reached in association with Flavobacterium sp. Our results provide the basis for further studies of monoxenic large scale production in liquid media and potentially development of these nematodes as promising mollusc biocontrol agents.