Hemicycliophora
Contents
Rev 05/05/2008
Hemicycliophora |
Contents |
Rev 05/05/2008 |
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| Sheath Nematode |
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Classification |
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Hosts |
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Morphology and Anatomy |
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Life Cycle |
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Economic Importance |
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Damage | |
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Distribution |
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Management |
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Feeding |
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References |
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Tylenchida
Tylenchina
Criconematoidea
Criconematidae
Hemicycliophorinae
Hemicycliophora (de Man, 1921)
Synonyms:
Procriconema (Micoletzky, 1925)
Colbranium (Andrássy, 1979)
Aulosphora (Siddiqi, 1980)
Loofia (Siddiqi, 1980)
There are at least 25 species of Hemicycliophora.
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Nematodes in this
genus are characterized by a
sheath - an extra cuticular layer that surrounds, sometimes quite loosely, each
life stage.
Female: Extra cuticular layer always present, generally loose, never membranous. Sloping stylet knobs. Labial annules two (exceptionally three), not modified or separated (except in H. hesperis and H. truncata). Vulva a transverse slit over half of body diameter long. Vagina straight or curved, but not sigmoid. Female tail: |
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Male: Labial region marked by a discontinuity in body
annulation, usually offset; labial framework in lateral view.
Spicules arcuate, semi-circular, U- or hook-shaped. Lips of cloaca forming a penial tube bearing a single hypoptygma at its tip. Caudal alae covering less than one-third of the tail. Tail longer than that of female. Males are rare in many populations. They have a degenerate esophagus and no stylet. Juvenile: Fourth-stage male juvenile without stylet. Ref: Raski and Luc (1987) H. Ferris Photomicrographs by I.A. Zasada |
Nematode common in sandy soils.
One of the first nematodes to cause damage on the new polders reclaimed from the former Zuiderzee in Holland. Initially the newly-reclaimed soil was free of plant-parasitic nematodes. In the Northeastpolder, reclaimed in 1942, infestations were already apparent by 1949 (Kuiper, 1977).
In the Northeastpolder in Holland, damage to carrot, bulbous iris, gladiolus and sugarbeet was caused by two species, Hemicycliophora conida and H. thienemanni.
Feed as ectoparasites, usually near root tip.
The adaptive significance of the sheath is uncertain, although it may provide protection from predaceous fungi as reported for the entomopathogenic nematode, Heterorhabditis spp. (Order: Rhabditida, Family: Rhabditidae) (Timper and Kaya, 1989).
Hemicycliophora spp. sometimes appear intolerant of low aeration associated with wet soil (e.g. H. arenaria in citrus, Van Gundy et al). In other cases, they are found in very wet, and rather anaerobic, sandy soils along stream banks.
Where two species were present in Holland, H. conida was mostly found in the topsoil while H. thienemanni dominated the deeper layers. Population levels of both species were greatest just below the tilled layer. Experiments revealed differences between the species in relation to soil moisture (Kuiper, 1977).
Usually causes root-tip swelling and stunted root/plant growth.
Hemicycliophora spp., occasionally occur in vineyard sites, especially in wetter areas. Although they parasitize grapevines, and are usually root tip feeders, the amount of damage they cause is unknown. They do, however, cause substantial damage in citrus (Van Gundy and Rackham, 1961).
See information on individual species.
Hemicycliophora spp. tend to be polyphagous so that crop rotation is difficult.
Applications of organic material to sandy soil inhibited population increase (Kuiper, 1977).
Nematicides are generally effective in the sandy soils in which these nematodes typically occur.
Raski and Luc, Rev. Nematol. 10(4):409-444 (1987)
H. Ferris
Kuiper, K. 1977. Introductie en vestiging van planteparasitaire
aaltjes in nieuwe polders, in het bijzonder van Trichodorus teres.
Wageningen Agricultural University dissertation no. 684.
