THE LIFE HISTORY OF MALAMEBA LOCUSTAE (KING AND TAYLOR) IN THE MIGRATORY GRASSHOPPER MELANOPLUS SANGUINIPES (F.)
Date
1987-09
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Degree Level
Masters
Abstract
Using both light and electron microscopy, the structure
and life history of the protozoan Malameba locustae (King
and Taylor) was studied in the migratory grasshopper
Melanoplus sanguinipes (F.). The ultrastructure of
trophozoites in both midgut and Malpighian tubules was
described. Trophozoites ranged in size from 7-11 pm. The
cytoplasm contained a nucleus with a prominent nucleolus,
many mitochondria with tubular cristae, numerous
lipid
drops, extensive RER and several autophagic vacuoles.
Binucleate trophozoites were common in the tubule lumen. As
trophozoites matured they became rounded, and the cytoplasm
became condensed, obscuring most of the cell organelles.
Numerous small vesicles appeared just inside the cell
membrane, and this was followed by the layered deposition of
cyst wall material. The completed cyst wall was
highly
refractive and about 0.5 pm thick.
Insects fed cysts had developed infection in the
Malpighian tubules when examined 5 to 6 days later.
However, no
trophozoites were seen in haemolymph samples
taken 2 days to 20 days post-feeding. After excystment, a
few trophozoites entered midgut epithelium where they
usually were extracellular. Many of those trophozoites in
midgut epithelium were located near the basement membrane of the epithelial cells, where they appeared to degenerate.
Trophozoites were not seen to divide in the midgut
epithelium, and apparently did not damage the host tissue.
Trophozoites injected directly into the haemocoel could not
be recovered even 4 h after injection, and the Malpighian
tubules did not become infected. It was concluded that
trophozoites did not penetrate the midgut to enter the
haemocoel or move
through the haemocoel to infect the
Malpighian tubules, but instead entered the tubules directly
from the gut.
Description
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Citation
Degree
Master of Science (M.Sc.)
Department
Biology
Program
Biology