Rev 03/16/2021
Length, female: 1.02-1.28 mm; length, male: 0.90-1.30 mm
Female:
Body elongate-cylindrical, C-shaped when relaxed, tapering anteriorly beyond esophagus to a set-off lip region.
Lip region hemispheroid, (bi-lobed, due to deep dorsal and ventral indentations) with distinct annules; basal annule with 6 to 12 longitudinal striations.
Cephalic framework strongly sclerotized, hexaradiate, lateral arms bipartite while subdorsals and subventrals are undivided.
Stylet massive, with knobs usually provided with 1-3 forwardly directed processes, tulip shaped; cone almost half of stylet length.
Dorsal esophageal gland opening 3-4 µm behind spear base.
Metacorpus spheroid, located at middle of esophagus, with well-developed valve.
Esophageal glands overlapping intestine dorsally and laterally; dorsal gland most anterior with 4 nuclei lying in one plane when seen laterally, while the nuclei of the 2 subventral glands lie in 2 planes; the lower one may be obscure.
Excretory pore 115-130 µm from anterior end, located above level of esophago-intestinal valve.
Hemizonid 6 annules (4-7 in some individuals) behind excretory pore, extending over 2 annules; hemizonid and hemizonion sometimes appear double.
Anterior phasmid on right and posterior on left side of body.
Nerve ring 20-25 µm anterior to excretory pore.
Cuticle coarsely annulated.
Lateral field a single incisure (sometimes 2 or 3, weakly developed and incomplete) becoming indistinct on most of body, not observed even in cross section.
Epiptygma indistinct, single, anterior; or double.
Spermatheca present, usually containing sperms.
Ovary outstretched, slightly obscured by intestinal globules. Intestine partially overlapping rectum.
Tail has 8-13 annules and bluntly rounded terminus.
Some of the morphological structures of diagnostic value such as the size of stylet, position of excretory pore, size, shape, and position of esophageal glands, overlap of intestine on rectum, and tail length vary in different populations associated with different crops (Husain & Rashid, 1969).
Male:
Similar to female in general morphology except for sex differences.
Testis single, outstretched; spicules arcuate and cephalated; gubernaculum with titillae.
Tail conoid, enveloped by bursa.
[Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 5, No. 66 (1975)]
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Widely distributed throughout India.
In rice roots, the nematode is both ecto- and endoparasitic (Das & Rao, 1969; 1970).
All stages of the nematode have been observed inside the root tissue, the fourth stage juveniles and adults being more common in soil.
In monoxenic cultures, the nematode feeds and reproduces on maize roots primarily as an ectoparasite, but may completely enter the root.
Sugarcane, tomato, rice, wheat, millet, sorghum, citrus, peach, sugarcane, and vegetables.
Ecophysiological Parameters:
Prior feeding is necessary for oviposition and development of successive post-embryonic stages. On sorghum roots, the life cycle from egg to egg is completed in 27-36 days and from egg to male in 25-27 days at 28-32 C (Dasgupta et al., 1969; 1970).
The first molt occurs within the egg, and the development outside the eggs consists of three larval stages and the adult, with the usual 3 molts.
Sex differentiation is indicated early in the second molt by the presence, in the female only, of four specialized ventral cord nuclei coinciding in position with that of the vagina. Minor variations in the details of the life cycle on different hosts have been reported.
Population density appears to be correlated closely with soil moisture content, although interaction with other factors such as soil temperature may be important. High soil temperature and drought conditions prevalent during summer months (April to June) and low temperature in December to January adversely affect the population.
The optimum conditions for maximum population growth are a temperature of 30 C, soil pH = 7, sandy loam soil (10-20% clay), and 16% moisture content.
In rice soils, more nematodes are recovered from nurseries and well-drained sandy soils, and fewest from ill-drained fields.
The presence or absence of host plants influences the field population considerably, especially in sorghum-wheat-cowpea and sorghum-wheat-fallow rotations.
Survival of nematodes in fallow soils is reported to be 57, 27, and 6% after 1,2, and 3 months, respectively (Das et al., 1970). [Ref: CIH Descriptions of Plant-parasitic Nematodes, Set 5, No. 66 (1975)]
In rice, the nematode causes stunted growth and suppression of ears; leaves become yellowish and brittle with the tips turning to an ash color; curling of leaves has also been observed; can cause complete crop failure.
Young sugarcane plants showed stunting of the upper internodes, drooping of the foliage, curling of new leaves, withered tips in older leaves, but crop later recovered.
Nematode may also facilitate entrance of Fusarium moniliforme fungus into plant tissue.
Host Plant Resistance, Non-hosts and Crop Rotation alternatives:
Nematicides are effective experimentally.
Leaving fields fallow for 3 months decreases nematode population.
Diazinon and DBCP were also effective as preplanting root dips at the rate of 500 ppm for 10 min. in reducing invasion by the nematode and its subsequent development inside the rice roots.
H. Ferris