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NOTES ON TAXONOMY AND BIOLOGY: This cyst forming nematode has sedentary endoparasitic habits and it is morphologically similar to H. cyperi. Cysts are persistent tanned sacs derived by the female body and contain the eggs. Cysts persist in soil for many years. Second-stage juveniles (J2) emerge from the cysts, penetrate host roots and establish a specialized feeding site (syncytium) in the stele. They develop producing swollen females, which retain the eggs without production of egg masses. Females rupture root cortex and protrude from the root surface. At the end of the reproductive phase, females die and become lemon shaped dark to mid-brown cysts. These cysts are ambifenestrate and usually lack bullae, but have a strong underbridge with a subcircular central mass. J2 have a lateral field marked by 3 incisures as that of H. cyperi. This species differs from H. cyperi by the longer female stylet (22-28 vs 22 µm) and by a large transparent subcircular mass attached to the underbridge, which is not present on the underbridge of H. cyperi cysts (Jairajpuri et al.1979).
GEOGRAPHIC DISTRIBUTION: This cereal cyst nematode has been reported only in India (CAB International, 2001).
HOSTS: This nematode infects finger millet (Eleusine caracana) (Swarup and Sosa Moss, 1990).
CROP LOSSES: The role played by this nematode in suppressing the yield of finger millet and probably corn is not known (Swarup and Sosa Moss, 1990).
MEANS OF MOVEMENT AND DISPERSAL: This cyst nematode is dispersed with soil debris and by plant material contaminated by the cysts.
RATING: (L) Uncertain damage and limited distribution of this ceral cyst nematode indicates a low priority for a complete risk assessment.
REFERENCES:
CAB International, 2001. Heterodera delviiin:
Crop protection compendium, global module, 3rd edition. Wallingford, U.K:
CAB International.
Jairajpuri, M. S., W. U. Khan, K.G.H. Setty and
H. C. Govindu. 1979. Heterodera delvii n. sp. (Nematoda: Heteroderidae),
a parasite of ragi (Eleusine coracana) in Bangalore, India. Revue
de Nématologie 2:3-9.
Swarup, G., and C. Sosa-Moss. 1990. Nematode parasites
of cereals. Pp. 109-136 in M. Luc, R. A. Sikora, and J. Bridge eds.
Plant parasitic nematodes in tropical and subtropical agriculture. Wallingford,
UK: CAB International.