Feeding biology of Diplogasteritus nudicapitatus and Rhabditis curvicaudata (Nematoda) related to food concentration and temperature, in sewage treatment plants.

The feeding biology of two bacterivorous nematodes found in percolating filter-bed sewage treatment plants were investigated in relation to food supply and temperature at all developmental stages. Temperature profoundly affected feeding activity and ingestion rates. As temperature increased ingestion rates increased. The larger species, Rhabditis curvicaudata possessed lower rates of pharyngeal pulsation than the small species Diplogasteritus nudicapitatus. R. curvicaudata reduced feeding activity as bacterial density fell from 8x109 cells ml-1 to 5x107 cells ml-1, below which it ceased feeding. D. nudicapitatus pumped continuously at a more or less constant rate irrespective of food density. The evolutionary and ecological aspects of these two patterns of feeding behaviour are discussed.