COMPARATIVE HISTOLOGY OF FEEDING SITES INDUCED BY CACTODERA ROSAE, GLOBODERA MEXICANA, AND MELOIDODERA ASTONEI (NEMATODA: HETERODERIDAE).

Histological studies were conducted on host plants infected by three species of nematodes of the Heteroderidae (Cactodera rosae, Globodera mexicana, and Meloidodera astonei). Cactodera rosae established a syncytium, which extended into the cortex, pericycle, phloem, and cambium of Amaranthus hybridus roots. The syncytial cells showed dense cytoplasm and hypertrophied nuclei and nucleoli. In Solanum rostratum roots, G. mexicana induced a syncytium that expanded from the pericycle into the stele incorporating phloematic elements and interfascicular cambial cells. The affected cells had dense cytoplasm, hypertrophied nuclei and nucleoli, and were surrounded by hyperplastic vascular parenchyma tissue. Females of M. astonei induced an uninucleate giant cell in the pericycle of S. rostratum roots. The giant cell, which had a dense cytoplasm and a hypertrophied nucleus, expanded in the tissues of the stele and especially in the secondary phloem. The cells of vascular parenchyma and secondary phloem tissues were hyperplastic. These anatomical changes are in agreement with those of other species of these genera reported in the literature. [ABSTRACT FROM AUTHOR]