Phases of maize rough dwarf virus multiplication in the vector Laodelphax striatellus (Fallén)

Maize rough dwarf virus (MRDV) was studied by electron microscopy in its principal insect vector, the planthopper Laodelphax striatellus (Fallén). It was found in many organs and tissues, and is therefore a virus that invades the animal host systematically. MRDV was observed not only as mature particles or virions; but transitional structures, presumably of its multiplication, were also found, particularly in mycetome cells. Eight fundamental phases of probable virus multiplication were identified, as follows: (1) phagocytic vesicles containing accumulations of isometric cores; (2) phagocytic vesicles containing pleomorphic cores; (3) phagocytic vesicles with granules; (4) bundles of granular microtubules; (5) bundles of microtubules with traces of granules; (6) tubular structures and fibrillar viroplasm, both with immature virus particles; (7) tubules, pseudotubules, and fibrillar viroplasm masses, all with virions; (8) aggregates of virions. Details about the various phases are given, and comparisons with other viruses showing microtubular structures are made and discussed.