Effects of Tsetse DNA Virus Infection on the Survival of a Host Fly,Glossina morsitans centralis(Diptera; Glossinidae)

Abstract

Freshly deposited third instarGlossina morsitans centralislarvae were infected with the tsetse DNA virus by microinjection. At emergence comparative observations were made on longevity and feeding behavior of infected and control flies. Gut tissues from the control and virus-infected flies were fixed and processed for light and electron microscopy. The longevity of infected flies was significantly reduced compared to that of the controls (P < 0.05). The main mortality factors in the virus-infected flies with severe lesions in the salivary glands were starvation due to failure to feed and clotting of blood in and/or rupture of the crop. Rupture of the midgut also caused some mortalities. Infected flies probed significantly more times during feeding to repletion (P < 0.05) and took significantly longer to feed compared to the control flies (P < 0.05). Infected flies which fed took significantly less blood compared to the controls (P < 0.05). Histological studies revealed pathological changes in the epithelial cells of the anterior midgut secretory midgut and the posterior midgut. There was severe disintegration of the membranous organelles, especially the mitochondria and rough endoplasmic reticulum, leading to extensive vacuolation in such epithelial cells. No viral particles were observed in the secretory and posterior midgut. Virions were observed in the anterior midgut lumen and occasional particles were seen invading the epithelial cells in this area of the midgut, especially in heavily infected flies.