Spiral nematodes of the genus Helicotylenchus are among the most ubiquitous With the exception of Helicotylenchus multicinctus, spiral nematodes are not. The damage symptoms are similar to those caused by other serious root endoparasites of the family Pratylenchidae, both on banana plants and plantains. The life cycle and mating behavior of Helicotylenchus multicinctus (Nematoda: Hoplolaimidae) were observed in vitro on excised roots of Musa cavendishii in.
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banana spiral nematode (Helicotylenchus multicinctus)
The common name spiral nematode is most helicotylencbus applied to nematodes in the genus Helicotylenchusbut it is also sometimes applied to other genera in the family Hoplolaimidae, including RotylenchusAorolaimusScutellonemaand Peltamigratus. These are called spiral nematodes because their bodies tend to curl into a spiral when the nematodes are relaxed or dead Figure 1. Spiral nematodes of the genus Helicotylenchus are among the most ubiquitous plant-parasitic nematodes worldwide.
Dozens of Multucinctus spp.
The body of Helicotylenchus spp. This moving nematode is outstretched. Photograph by William T. CrowUniversity of Florida. The body of Helicotylenchus and other spiral nematodes curve into a spiral when the nematode is dead or relaxed. These relaxed nematodes are curled into a spiral.
Reproduction is highly variable among species of Helicotylenchus. Some species, like Helicotylenchus muticinctusreproduce sexually and have males and females that mate. Some species are hermaphrodites that self-fertilize their own eggs without mating. Other species, like Helicotylenchus pseudorobustus, reproduce asexually by parthenogenesis, do not mate, and have only females.
Females lay eggs individually in soil. Inside each egg a first-stage juvenile develops and then molts into a second-stage juvenile before hatching. After hatching, the second-stage juvenile must locate a host plant and begin feeding for further development.
The nematode inserts its mouth-spear stylet into the epidermis and cortical cells and ingests the cellular contents. In some cases, Helicotylenchus pseudorobustus induces development of a specialized food cell on which it feeds Vovlas and Inserra This food cell is not larger than a typical cortical cell, but has denser cytoplasm and larger nucleus than a normal cell.
Helicotylenchus pseudorobustus will generally stay in one location feeding on a single food cell, but can also move to a different location on the same or different root and induce a new food cell at the new location. While generally considered an ectoparasite whose body remains outside of host tissue during feeding, occasionally Helicotylenchus pseudorobustus behaves as a semi-endoparasite and penetrates into the host root with its anterior body portion head region.
In contrast, Helicotylenchus multicinctus is a migratory endoparasite that enters completely into banana roots and moves in the lumen between cells, feeding on different cells as it migrates. After feeding, all Helicotylenchus spp. The various juvenile life stages of Helicotylenchus spp. Eggs of most species are deposited into the soil, although Helicotylenchus multicinctus lays eggs within banana roots.
With the exception of Helicotylenchus multicinctusspiral nematodes are not considered important pests on most hosts. However, often their damage has not been well quantified or documented. Research has shown that some Florida crops, such as soybean, cotton, and corn are damaged by Helicotylenchus pseudorobustus.
Helicotylenchus multicinctus is an important nematode helicofylenchus of banana in Florida McSorley and Parradoand worldwide McSorley and Parrado Helicotylenchus paxilli has been demonstrated to reduce growth of bermudagrass and seashore paspalum used on Florida golf courses Pang et al. The symptoms of Helicotylenchus pseudorobustus are more subtle than those of certain other nematodes such as root-knot or sting nematodes.
Heavy infection by Helicotylenchus spp. On turfgrasses, Helicotylenchus paxilli has been shown to reduce root length and cause thinning of turf. Generally the turf decline will occur in patches Figure 3 and is often accompanied by proliferation of weeds in the affected areas Figure 4. Helicotylenchus multicinctus causes small necrotic lesions on roots, and with heavy infestation these lesions coalesce, leading to root necrosis and die-back of roots.
Plant stunting helicootylenchus reduction in yield can result. Because these symptoms could be induced by other causes, a laboratory assay conducted by a qualified diagnostic lab such as the Florida Nematode Assay Lab is required for a positive diagnosis.
Seashore paspalum on a golf course fairway infested by Helicotylenchus paxilli. Nematode damage is visible as patches of declining turf.
A seashore paspalum golf tee box infested with Helicotylenchus paxilli. Nematode damage results in thinning turf and proliferation of weeds.
As previously described, the body of Helicotylenchus spp. The tail is asymmetrical, being curved dorsally with a rounded projection in many species Figure 6.
The presence of males is a useful biological character to separate Helicotylenchus multicinctus from species that do not have males. A combination of morphological evaluation, morphometrics, hellcotylenchus molecular phylogenetic inference should be used to accurately determine the species of an individual population Subbotin et al. An adult Helicotylenchus paxilli. The tail of Helicotylenchus pseudorobustus is asymmetrical and multjcinctus a projection on the end.
While Helicotylenchus pseudorobustus is a parasite of many economically important plants, it is seldom considered a major pest on most multkcinctus them.
In Florida, heelicotylenchus paspalum, a turfgrass used in tropical and subtropical regions, is particularly susceptible to infestation by Helicotylenchus paxilli. On this grass, Helicotylenchus paxilli is among the most common nematodes requiring nematicide application in Florida.
While banana is not an important commercial crop in Florida, Helicotylenchus multicinctus is damaging to banana grown for multicincyus fruit consumption and ornamental banana growing in nurseries and landscapes. Another species that is very common on many crops, ornamentals, and other cultivated and non-cultivated plants in Florida is Helicotylenchus dihystera. However, the damage induced by this nematode in Florida has not been assessed.
The extensive host range of Helicotylenchus spp. Because the body of Helicotylenchus spp. On golf and sports turfgrasses, nematicides are applied for management of Helicotylenchus paxilli in Florida. Refer to Nematode Management for Golf Courses in Florida for current management recommendations on golf course turf. Sanitation, planting of nematode-free banana plants into non-infested soil, is currently the best control measure for Helicotylenchus multicinctus on banana in nurseries and landscapes.
Hoplolaimidae Introduction – Distribution – Life Cycle and Biology – Hosts – Symptoms – Identification – Milticinctus Importance – Management – Selected References Introduction Back to Top The common name spiral nematode is most often applied to nematodes in the genus Helicotylenchusbut it is also sometimes applied to other genera in the family Hoplolaimidae, including RotylenchusAorolaimusScutellonemaand Peltamigratus.
Distribution Back to Top Helicotylenchus spp. Hosts Back to Top Helicotylenchus spp. Symptoms Back to Top The symptoms of Helicotylenchus pseudorobustus are more subtle than those of certain other nematodes such as root-knot or sting nematodes.
Identification Back to Top As previously described, the body of Helicotylenchus spp. Economic Importance Back to Top While Helicotylenchus pseudorobustus is a parasite of many economically important plants, it is seldom considered a major pest on helicotylenchue of them. Management Back to Top The extensive host range of Helicotylenchus spp. Morphometrical variability in Helicotylenchus Steiner, Study of field populations of H.
The spiral nematode Helicotylenchus multicinctus on bananas in Florida and its control. Proceedings of the Florida State Horticultural Society Helicotylenchus multicinctus on bananas: Helicotylenchus species as crop damaging parasitic nematodes. Responses of seashore paspalum cultivars to sting and spiral nematodes. Field responses of bermudagrass and seashore paspalum to sting and spiral nematodes.
Journal of Nematology Diversity and phylogenetic relationships within the spiral nematodes of Helicotylenchus Steiner, Tylenchida: Morphological and molecular characterisation of Helicotylenchus pseudorobustus Steiner, Golden, and related species Tylenchida: Holplolaimidae with a phylogeny of the genus.
Vovlas N, Inserra R.
Single modified food cell induced by Helicotylenchus pseudorobustus in corn roots. Vovlas N, Larizza A. Embryonic patterns and parasitic habits of Helicotylenchus oleae and H. Afro-Asian Journal of Multicinctuw 4: