Rev 04/03/2021
Tylenchorhynchus dubius (Buetschli, 1873) Filipjev, 1936
Synonyms: Tylenchus dubius Buetschli, 1873 Tylenchus (Bitylenchus) dubius (Buetschli, 1873) Filipjev, 1934. Anguillulina dubia (Buetschli, 1873) Goodey, 1932 Tylenchorhynchus dubius Thorne (1949) = T. cylindricus Cobb (1913)
Length, female: 0.62-0.78 mm; length, male: 0.65-0.71 mm.
Female: Body ventrally arcuate in fixed specimens; cylindrical, tapering slightly at both ends.
Annules fine, about 0.8 µm wide.
Lateral fields marked with 4 longitudinal incisures, outer bands incompletely areolated.
Deirids absent.
Phasmids distinct in both sexes, anterior to or near middle of tail.
Lip region hemispherical, offset by a constriction, with 6 to 7 annules; weak head sclerotization.
Stylet well developed with posteriorly sloping, rounded basal knobs.
Orifice of dorsal esophageal gland about 2 or 3 µm behind stylet base.
Median esophageal bulb large, oval, with prominent refractive valve apparatus in center.
Narrow isthmus.
Basal bulb elongate-pyriform; esophago-intestinal valve hemispherical.
Excretory pore near base of isthmus, just posterior to hemizonid, which is about 2 annules long.
Ovaries outstretched, with oocytes in a single row extending one-half to two-thirds the distance to end of tail.
Spermatheca rounded, with sperms.
Vulva median.
Male: Abundant. Similar to female.
Spicules arcuate, about 26 µm long along the arc, with ventral flanges distally.
Gubernaculum about 12 µm long, protrusible, its proximal end rounded.
[Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 4, No. 51 (1974)]
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Common in Europe, but infrequent in the U.S.
Nematode prefers sandy soils.
Ectoparasite - browses on epidermal cells and root hairs, and may be attracted to zone of elongation in sugarbeets.
All stages are parasitic; average feeding time is 10 min. before moving top another root hair or epidermal cell (Klinkenberg, 1963).
Feeding causes reduction of cytoplasmic streaming in epidermal cells.
Feeding occurs in three stages:
Pasture, pine, spruce, grasses, cabbage, carrot, sugarbeet, corn, and cereals.
Ecophysiological Parameters:
Males are required for reproduction.
All stages are susceptible to desiccation.
Sharma (1971) showed that the complete life cycle from egg to egg took 40-48 days in tap water at 20 C: 8 days after a one-celled egg was laid, the first molt occurred inside the egg, quickly followed within hours by the hatching of the L2 juvenile; the L3 stage was reached after 12 days; the L4 stage after 16 days; and adult after 32 to 40 days.
Causes stunting and reduced root system of field beans in England; poor growth of oats in the Netherlands; reduced tops and root system of creeping bentgrass (Agrostis palustris) and Kentucky bluegrass (Poa pratensis) in Michigan.
Nematode feeding may predispose P. pratensis to attack by fungus (Fusarium roseum).
A small amount of nematicide, e.g., 3.5 gpa ethylene dibromide (EDB) (placed 8 in. deep and 10 in. apart) was effective on sugarbeets in England, as was 8 gpa 1,3-Dichloropropene (1,3-D) placed in rows.
Application of oxamyl and Aldicarb improved growth of bentgrass in Michigan.
Organic and green manures of Lupinus sp., Tagetes patula (marigold), and fallen apple leaves effectively controlled T. dubius populations (Skarbilovich, 1970), and populations were also reduced after cultivation of various Compositae (Hijink & Suatmadji, 1967).
Host Plant Resistance, Non-hosts and Crop Rotation alternatives:
CIH Descriptions of Plant-parasitic Nematodes, Set 4, No. 51 (1974)
Klinkenberg, C.H. 1963. Observations On the Feeding Habits of Rotylenchus uniformis, Pratylenchus crenatus, P. penetrans, Tylenchorhynchus dubius and Hemicycliophora similis. Nematologica 9:502-506.