The tsetse flies, Glossina spp, are important blood-feeding flies found in Africa (latitude 5°N–20°S). Tsetse flies are narrow bodied, yellow to dark brown, and 6–13.5 mm long. When resting, their wings are held over the back in a scissorlike configuration. The thorax is a dull greenish color with inconspicuous spots or stripes. The abdomen is light to dark brown.
Both sexes are avid blood feeders. One copulation renders a female fly fertile for its lifetime, during which it can produce as many as 12 larvae. It produces one larva at a time, retaining it within its uterus; after approximately 10 days, the larva is deposited on loose, sandy soil, where it digs in and begins pupation within 60–90 minutes. This pupation period averages approximately 35 days, after which the adult emerges. Adult flies feed avidly on vertebrate blood approximately every 3 days (1).
Pathology of Tsetse Flies
Tsetse flies serve as the intermediate hosts for several species of trypanosomes that cause fatal diseases of both domestic animals (nagana) and humans (African sleeping sickness). Trypanosomes invade the blood, lymph, CSF, and various organs of the body, such as the liver and spleen.
Nagana, a related complex in cattle due toTrypanosoma brucei, has occurred throughout enormous areas estimated to be as great as one quarter of the African continent (1). The disease is fatal to horses, mules, camels, and dogs. Cattle, sheep, and goats usually survive, except when parasitized by certain strains. Many wild ungulates native to Africa show no evidence of harm. (Also see Trypanosomiasis in Animals.)
Diagnosis of Tsetse Flies
Tsetse flies can be identified by their honeybee-like appearance, long proboscis with its onion-shaped bulb at the base, and unique wing venation with the characteristic cleaver- or hatchet-shaped cell in the center of the wing.
Treatment and Control of Tsetse Flies
Insecticide sprays, traps, and insecticide-impregnated targets
Aerial treatment
Treatment of production animals using trypanocides
Tsetse flies can be controlled by catching and trapping (tsetse traps), bush clearing, fly screens, repellents, and insecticides. Experimental field release of gamma sterilized male Glossina palpalis gambiensis has shown promise for an area-wide IPM campaign with a sterile insect component (2).
For More Information
References
Leak SGA. Tsetse Biology and Ecology: Their Role in the Epidemiology and Control of Trypanosomiasis. CABI Publishing/International Livestock Research Institute; 1999.
Pagabeleguem S, Koughuindida O, Salou EW, et al. Gamma-radiation of Glossina palpalis gambiensis revisited: effect on fertility and mating competitiveness. Parasite. 2023;30(8). doi:10.1051/parasite/2023009
