ULTRASTRUCTURE AND PATHOLOGY OF MICROSPORIDIUM-PHYTOSEIULI N-SP INFECTING THE PREDATORY MITE, PHYTOSEIULUS-PERSIMILIS ATHIAS-HENRIOT (ACARI, PHYTOSEIIDAE)
S. Bjornson et al., ULTRASTRUCTURE AND PATHOLOGY OF MICROSPORIDIUM-PHYTOSEIULI N-SP INFECTING THE PREDATORY MITE, PHYTOSEIULUS-PERSIMILIS ATHIAS-HENRIOT (ACARI, PHYTOSEIIDAE), Journal of invertebrate pathology, 68(3), 1996, pp. 223-230
Ultrastructure and pathology of Microsporidium phytoseiuli n. sp. infe
cting the predatory mite Phytoseiulus persimilis Athias-Henriot is des
cribed using light and transmission electron microscopy. Infected mite
s showed no gross, external symptoms, All observed stages of the paras
ite had unpaired nuclei. Schizonts were commonly observed within nucle
i of digestive cells of the ventriculus and within the cytoplasm of ce
lls lining the cecal wall and in muscle tissue underlying it. Sporobla
sts and spores occurred in the nuclei and cytoplasm of digestive cells
within the ventriculus, in cortical regions of the sub- and supraesop
hageal ganglia, within the cecal wall and muscle tissue, and in parenc
hyma cells underlying the cuticle. Mature spores were also observed in
developing eggs within gravid females. These were broad- to elongate-
ovoid, measured 4.33 +/- 0.35 x 1.27 +/- 0.15 mu m (electron micrograp
hs), 5.37 +/- 0.46 x 2.22 +/- 0.17 mu m (fixed and stained), and 5.88
+/- 0.34 x 2.22 +/- 0.19 mu m (fresh) and had an isolfilar polar filam
ent coiled 12 to 15 times within the posterior two-thirds. Within cell
s, individual spores appeared to be in direct contact with host cytopl
asm, while groups of spores were infrequently observed within interfac
ial envelopes. Groups of 4, 8, to more than 16 spores were observed by
light microscopy, while 8 was the maximum observed by electron micros
copy. No spores were observed in Tetranychus urticae, a mite used as f
ood during this study. (C) 1996 Academic Press, Inc.