Artificial feeding of Ornithodoros concanensis (Acari: Argasidae) nymphs on bovine blood and morphological changes in erythrocytes undergoing hemolysis in the tick midgut.

The morphology of bovine erythrocytes undergoing hemolysis in the midgut of the argasid tick Ornithodoros concanensis Cooley & Kohls was examined after feeding nymphal ticks artificially on parafilm and latex membranes. Percentage of successful feeding was significantly higher on parafilm (63%) than on latex (43%) membrane. However, there was no difference in the amount of blood taken per tick. Scanning electron microscopy was used to follow the morphological changes of red blood cells in the tick gut during an 80-h postfeeding period. Erythrocytes converted from normal discocytes to spiculated cells (echinocyte stage III) within 20 h. During the development of spicules (echinocytosis), erythrocytes lost membrane surface area by the release of microvesicles. At 30 h after feeding, the first spherocytes appeared and after 80 h, only smooth spheres of different sizes were present. Reasons for the observed modifications in red blood cell morphology are discussed.