Parasitic nematodes (Family: Hoplolaimidae) associated with ornamental palnts in Guilan Province

Ornamental plants are grown for decorative purposes in gardens and landscape design projects, as houseplants, for cut flowers and specimen display. The cultivation of these, called floriculture, forms a major branch of horticulture. Nematodes are a diverse group of wormlike animals found in a number of habitats. Plant-parasitic nematodes are recognized as one of the greatest threats to crops throughout the world. Nematodes alone or in combination with other soil microorganisms have been found to attack almost every part of the plant including roots, stems, leaves, fruits and seeds. Hoplolaimidae is a family of plant parasitic nematodes. The common name, spiral nematode, is most often applied to nematodes in the genus Helicotylenchus, but it is also sometimes applied to other genera in the family Hoplolaimidae. These are called spiral nematodes because their bodies tend to curl into a spiral when the nematodes are relaxed or dead. The spiral nematodes have been reported in the worlds associated with various cultivated horticultural, agronomic, ornamental, and turfgrass plants.
Materials and Methodes: In order to identify the ornamental plants parasitic nematodes in Guilan province, 115 soil samples from rhizosphere of various species of ornamental plants in greenhouse and landscaping were collected from different parts, during the summer and fall in 2011-12. After extraction, fixation and transferring nematodes to anhydrous glycerol, the nematodes were mounted on permanent microscopic slides and nematode species were identified by using light microscope, equipped with drawing tube and digital camera, based on morphological and morphometric characters using valid identification keys.
In this research, 7 nematode species belonging to Hoplolaimidae family including Helicotylenchus dihystera, H. erythrinae¡ H. exallus, H. Microlobus, H. Pseudorobustus, H. sharafati and Scutellonema brachyurus were indentified. Two species, H. pseudorobustus and H. sharafati were reported for the first time from Iran.
H. microlobus is distinguished from close speciecs by lack of areolation on the tail, fusing of inner incisures of the lateral fields distally for about two annules and unclear phasmid. Distinguishable charatcters of H. Sharafati from close species are as below: less labial annules, angular spear knobs and differently shaped tail with characteristic endings of lateral fields. There is no measurement and description of H. erythrinae available in Iran so the description of this species is also illustrated.