Research Product

Cell size and type may affect availability of bacteria for consumption by bacterivorous nematodes in the soil and in culture. This study explored the feeding preferences of the bacterivorous soil nematode Cephalobus brevicauda (Cephalobidae) by comparing bacteria isolated directly from soil, from commercial bacterial biological control agents, and from in vitro soil nematode cultures. The 16S rRNA sequences of bacterial isolates were compared to known sequences to identify phylogenetic affiliations. Food preference of the nematode was observed by counting the number of C. brevicauda that were attracted to a bacterial food source in a bioassay. Additionally, the reproductive output of single females reared on the bacteria was recorded. An attraction index established that C. brevicauda preferred to feed upon gram-negative, small-volume bacteria, however these bacteria did not support maximum reproductive success. Bacterial biocontrol agents had no negative effects on reproduction, but C. brevicauda always preferred other bacteria to DipelŪ, (Bacillus thuringiensis ssp. kurstaki) in the food preference assay.