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NOTES ON TAXONOMY AND BIOLOGY: Like other cyst forming nematodes, it 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 and penetrate host roots, where they establish a specialized feeding site (syncytium) in the stele. They develop into swollen females, which retain the eggs and produce small egg sacs containing a few eggs. Females rupture root cortex and protrude from root surface. At the end of the reproductive phase, females die and become lemon shaped light brown cysts. These cysts are ambifenestrate and have a few bullae, a robust underbridge and an indistinct anus.
GEOGRAPHIC DISTRIBUTION: This species is common in Egypt, India and Pakistan. It is present, but is not known to be widely distributed in Thailand and USA, where it was detected in Maryland and Virginia.
HOSTS: This species parasitizes mainly monocots and especially corn (Zea mays). Other hosts include barley (Hordeum vulgare), German millet (Setaria italica), oats (Avena sativa), rice (Oryza sativa), sorghum (Sorghum bicolor), Sudan grass (Sorghum sudanensis), teosinte (Zea Mexicana) and wheat (Triticum aestivum).
CROP LOSSES: Warm temperatures 27 C (80 F) and 33 C (91 F) favor crop damage induced by this species. Growth suppressions of 30% and 27 % were observed at the above temperatures (Hashami et al., 1993).
MEANS OF MOVEMENT AND DISPERSAL: This cyst nematode is dispersed with soil debris, plant material and machinery contaminated by the cysts.
RATING: (M) Taking into consideration the damage caused by this nematode in India and Egypt, and the introduction and establishment of this pest in Maryland and Virginia, USA., we urge regulatory agencies in corn producing states to adopt adequate measures to prevent the spread of this pest from Maryland and Virginia to other corn growing states and especially, to those located in warm climates in the US. Appropriate actions should be taken by APHIS in order to minimize the risks of the introduction of this nematodes from other countries.
REFERENCES:
CAB International. 2001. Heterodera zeaein
Crop protection compendium, global module, 3rd editon. Wallingford, UK:
CAB International.
Eisenback, J. D., D. M. Reaver, and E. L. Stromberg.
1993. First report of corn cyst nematode (Heterodera zeae) in Virginia.
Plant Disease 77;647.
Hashami. S., L. R. Krusberg, and S. Sardanelli.
1993. Reproduction of Heterodera zeae and its suppression of corn
plant growth as affected by temperature. Journal of Nematology 22:55-58.