Abstract
The growth and reproduction of Plectus sp. and Rhabditis sp., the most frequent detected nematodes from tap water, were investigated at different conditions. Only females of Plectus sp. were found, but most of Rhabditis sp. were. self-fertilizing hermaphrodite while males were rare. It was found that Plectus sp. and Rhabditis sp. did not reproduced well or survived when temperature was below 5°C and/or above 35°C, respectively. It is shown that pH range for reproduction of Rhabditis sp. was wider than Plectus sp. The specific growth rate of Rhabditis sp. was still high even at pH4 or pH9, whereas that of Plectus sp. was very low or not observed at these conditions. Inoculated concentrations of bacteria (E. coli C600) as food highly influenced to the egg-laying of both nematodes. However, the mortality of Rhabditis sp. was far larger than Plectus sp. at the same bacterial concentrations. At 20°C, pH6 and inoculated bacterial concentrations of 108 cells·ml-1, the specific growth rates of Plectus sp. and Rhabditis sp. were 1.0 and 0.6d-1, respectively.
