Tsetse fly
The tsetse fly, belonging to the genus Glossina, is a significant parasitic insect found in tropical Africa and southwestern Arabia. These blood-sucking flies are notorious for transmitting trypanosomiasis, commonly known as sleeping sickness, which can be lethal to both humans and animals. Tsetse flies are characterized by their unique wing-folding behavior when resting, as well as their specialized mouthparts designed for piercing skin and sucking blood. They inhabit varied environments, including savannas, forests, and areas near rivers and lakes, and are categorized into three subgenera based on their habitats.
Tsetse flies have a complex reproductive cycle, giving birth to a single larva at a time, which then burrows into the soil to pupate. Their relationship with symbiotic plants in their digestive systems helps them process the blood they consume. While sleeping sickness poses a serious health risk, there are preventive measures, such as habitat management and introducing infertile male flies, to help control their populations. Understanding the biology and ecology of tsetse flies is crucial for combating the diseases they spread and protecting both human and animal health in affected regions.
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Tsetse fly
Five species of tsetse fly are feared by people in tropical Africa and southwestern Arabia because they transmit the deadly disease of sleeping sickness to people and animals. This disease may kill someone either after years or only after a few months.
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Glossinidae
Genus: Glossina
Species: Various (see below)
The blood-sucking tsetse fly is in the same family as the common housefly. They are divided into three subgenera. The Morsitans group lives in Africa's savannas, species in the Fusca subgenus live in forests, and those in the group Palpalis are called riverine or lacustrine flies.
These flies are large, measuring 1/5 to just over 1/2 inch (6 to 16 millimeters) long. There are many species of tsetse flies, but only a few carry a deadly disease called trypanosomiasis, commonly called sleeping sickness. These flies live alone in grasslands and forests along rivers and lakes in tropical regions of Africa between the Sahara and Kalahari Deserts and in southwestern Arabia.
Tsetse flies have bodies, wings, and halteres similar to houseflies. Halteres are two club-like sensory organs behind each fly's two wings which help it balance as it flies and keep it on a straight course. One difference between houseflies and tsetse flies is that tsetse flies fold their wings over their backs and on top of each other when they are resting. Houseflies rest their wings side by side.
Another difference between houseflies and tsetse flies is their mouthparts. Tsetse flies have mouthparts that are designed to pierce the skin of mammals, including humans, reptiles, and birds to suck blood. These mouthparts are a set of forward-pointing, needle-like tubes. They have sharp teeth on the tips to saw into the skin. One tube carries saliva into the victim's skin and contains chemicals to prevent the blood from clotting. The other tube sucks the blood.
Tsetse flies are parasitic insects, which means they feed on other living creatures, called hosts. The flies have tiny plants living inside their stomachs which help the flies digest the blood they suck and also provide nutrients to the flies. These plants are not parasites. Because the flies and the plants help and do not harm each other, they have a symbiotic relationship.
Tsetse flies mate year round. The females only have one young at a time, and they have no more than 12 young in their lifetimes, which range from one to six months. Each egg hatches into a larva inside its mother and is born as a full-grown, white, worm-like maggot. The mother deposits the maggot in the shade of a tree, shrub, or log. It immediately burrows into the soil and becomes a brown pupa, which is the form it has between being a larva and an adult. After one month it crawls from the ground and hatches from its pupal case into an adult.
Tsetse flies are dangerous because they carry a deadly disease called trypanosomiasis which is commonly known as sleeping sickness. Microscopic organisms called trypanosomes infect the flies. Trypanosomes are among the many species of tiny, organisms called protozoans. Inside the flies, the trypanosomes develop into forms that can infect people with the disease. When the flies bite animals or people, the trypanosomes enter the victims' bodies and multiply. Their bite is painful. Sleeping sickness causes its victims to become very tired. Some animals do not get sleeping sickness, but they carry the trypanosomes inside them and can pass them to flies which bite them and then people.
Sleeping sickness may be treated with medication. People may prevent the disease by clearing or burning vegetation where the flies live, spraying poisons, killing diseased animals, and introducing male tsetse flies which cannot fertilize the females' eggs.
A female tsetse fly mates one time and develops her young in a special sack. Before they hatch, she buries them in the ground where they develop into larvae. They remain larvae for 20 to 30 days before becoming flies.
The lifespan of a female tsetse fly is one to four months, but males live around two to three weeks.
Bibliography
"African Trypanosomiasis (African Sleeping Sickness)." Centers for Disease Control and Prevention, 16 Sept. 2022, wwwnc.cdc.gov/travel/diseases/african-sleeping-sickness-african-trypansosomiasis. Accessed 15 May 2024.
"Tsetse Fly." A-Z Animals, 15 Mar. 2023, a-z-animals.com/animals/tsetse-fly. Accessed 15 May 2024.