Analysis Of Nematode Population Of Cucumber Rhizosphere In He'nan Greenhouse & Identification Of Insect Nematode Isolates

Analysis on cucumber rhizosphere nematode populations and isolated insect nematode identification were carried out in this study.Forty-four soil samples were collected in LianCheng township, Tongxu county, Kaifeng city, He'nan province during almost whole cucumber growing season in greenhouse from December 2003 to April 2004. All nematodes isolated from the rhizosphere soil were identified into 16 genera belonging to 11 families of 5 orders, among which Acrobeloides, Acrobeles, Rhabditis, Peladera, Trilabiatus, Aporcelaimus and Mononchus were the first record in He'nan province.The results on nematode population dynamics shown that: (1) the amount of nematodes in the soil was increased from December 2003 to April 2004 and the trends of various trophic groups were different, the group of bacterivores went down and that of phytophage and insect nematode grown up; (2) more than 90% nematodes in cucumber rhizosphere in greenhouse were bacterivores, phytophages and insect nematodes; (3) fungivores and omnivore-predator nematodes took only small quantity proportion; (4) among plant parasites root-knot nematodes and stunt nematodes were predominant populations which increased along with the seasons, after March they grown extremely faster than before, from which we presumed that these two co-occurred populations caused much more damage than their alone in April.According to the relationship of bacterivores nematode and bacteria, it was suggested that insect nematode should be separated from the trophic group of bacterivores since insect nematode is not predator but has symbiosis relationship with bacteria. Therefore the nematode populations were classified into 5 groups in this study: insect nematode, bacterivores, phytophages, omnivore predators, and fungivores.Fifteen insect nematode isolates were identified to five genera which included Rhabditis, Dolichorhabditis, Phasmarhabditis, Pelodera and Panagrellus. PCR amplification of the 13 isolates in 2 genera in rDNA region yielded one fragment of 750-1000bp, none in control. Two fragments of 100bp and 300bp were obtained in all samples of the 4 isolates by enzyme Hinfl digestion. There was no difference in RFLP map, which may approve that Hinfl alone could not distinguish the 4 insect nematode isolates.