| Summary: | 碩士 === 國立中興大學 === 植物病理學系所 === 100 === Free-living, predatory and plant-parasitic nematodes that associated with the commercial submerged aquatic plants were surveyed in the study. Seventy-six species from 20 dicotylendonous families and 5 monocotylendonous families were investigated. Six families of free-living nematodes were found to associate with aquatic dicots in the families of Chronogasteridae, Diplopeltidae, Leptolaimidae, Mesorhabditidae, Rhabditidae and Tripylidae. The predatory nematodes in the families of Actinolaimidae, Anatonchidae, Cyanotholaimidae and Dorylaimidae were attained from aquatic dicots. Only one genus of plant-parasitic nematodes, identified as Aphelenchoides, was isolated from aquatic dicots, and the greatest amount of Aphelenchoides spp. were found from Cabomba aquatic plants. From monocotylendonous aquatic plants, free living nematodes in the families of Cephalobidae, Chronogasteridae, Leptopaimidae, Mesorhabditidae, Panagrolaimidae, Plectidae, Rhabditidae, and Tripylidae were detected. Nine families of predatory nematodes in the families of Actinolaimidae, Aporcelaimidae, Belondiridae, Dorylaimidae, Metateratocephalidae, Mononchidae, Mylonchulidae, Sphaeroliamidae and Tylencholaimellidae were found from aquatic monocots. Parasitic nematodes belonging to Aphelenchoides, Meloidogyne and Hirschmanniella were also found from aquatic monocots. Chronogateridae of free-living nematodes and Dorylaimidae of predatory nematodes were the two dominant families found in this survey, aquatic plants might provide the main food resources and a suitable habitat for Chronogateridae and Dorylaimidae populations. There were only three genus of plant-parasitic nematodes found in this survey. The morphology of Aphelenchoides spp. from C. aquatic was similar with an Aphelenchoides new species reported by Yang. There were only two Hirschmanniella individual females isolated in this survey which were not sufficient for species identification. Significant galling symptoms caused by Meloidogyne spp. were observed on the anubias roots. The perineal pattern had closed lines with lower and disorderly dorsal arch. Lateral ridges and subcuticular punctuations surrounding the anus were absent. The morphology of perineal pattern indicated the root knot nematodes might be M. arenaria. The mitochondria DNA sequence of COII region from five single female populations all yielded an approximately 1.7 kb fragment, and the SCAR-PCR yielded specific bands, indicated that the root knot nematodes were M. arenaria or M. incognita, respectively.
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