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Pest Description
IDENTITY: Scientific name: Heterodera elachista
Ohshima, 1974
Common name: A rice cyst nematode

NOTES ON TAXONOMY AND BIOLOGY: This cyst forming nematode has sedentary endoparasitic habits. 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 into swollen females, which retain the eggs and produce large egg masses. Females rupture root cortex and protrude from root surface. At the end of the reproductive phase, females die and become rounded dark or black cysts. These cysts are ambifenestrate and have a long vulval slit, rounded semifenestra, few bullae and a weakly developed underbridge, which is often absent. Heterodera elachista is morphologically close to H. oryzae, H.oryzicola and H. sacchari. The separation of these species requires morphological and biochemical techniques (Luc, 1986; Nobbs, et al., 1986)

GEOGRAPHIC DISTRIBUTION: This species has been reported only in Japan.

HOSTS: Rice (Oryza sativa) is the primary host of this species (Luc, 1986).

CROP LOSSES: The damage induced by this nematode ranges 7-19 % (Bridge et al., 1990).

MEANS OF MOVEMENT AND DISPERSAL: This cyst nematode is dispersed with soil debris and by plant material contaminated by the cysts.

RATING: (L) Taking into consideration the limited host range of this nematode and the low chance of its introduction into the US, the working group ranked this nematode as one with a low priority for a complete pest risk assessment.

    Bridge, J., M. Luc, and R. A. Plowright. 1990. Nematode parasites of rice. Pp. 69-108. in M. Luc, R. A. Sikora, and J. Bridge eds. Plant parasitic nematodes in tropical and subtropical agriculture.  Wallingford, UK: CAB International.
    Luc, M. 1986. Cyst nematodes in equatorial and hot tropical regions Pp.355-372. in F. Lamberti and C.E. Taylor  eds. Cyst nematodes.  New York: Plenum Press.
    Nobbs, J. M., S. K. Ibrahim, and J. Rowe. 1992. A morphological and biochemical comparison of the four cyst nematodes species, Heterodera elachista, H. oryzicola, H. oryzae, and H. sacchari (Nematoda:Heteroderidae) known to attack rice. Fundamental and Applied Nematology 15:551-562.