The tsetse fly has the glory of an extremely dangerous insect. It is capable of causing a disease in people and animals called trypanosomiasis. There are two forms of this infection: Rhodesian trypanosomiasis, sometimes referred to as East African, and Gambian, or West African. Rhodesian is transmitted from animal to animal and mainly affects cattle, horses, wild ungulates. The Gambian form is common among people and is commonly referred to as sleeping sickness. Tsetse fly lives only in Africa. 22 known species of this insect. It is active throughout the day and feeds exclusively on blood.
Most insects are usually careless parents. The female lays eggs and flies away, leaving the young to survive on their own. The tsetse fly differs from other insects in that it treats its offspring very carefully. The female lays one egg, but she keeps it in the safest place - in her womb. The egg turns into a larva that grows by feeding on a fluid that is rich in fat, which scientists call "intrauterine milk." When the larva completely fills the uterus of the mother, it releases it into the moist soil. The larva hides and immediately pupates.
Studies have shown that "milk" contains the enzyme sphingomyelinase, which is activated in an acidic environment in the digestive tract of the larva. Sphingomyelinase is involved in the metabolism of fats and the formation of cell membranes. This enzyme has similar functions in mammals and tsetse flies during lactation, despite the enormous evolutionary distance between these classes. In addition to the parasitic organism, trypanosomes, there is another bacterium that lives in its digestive tract, which simultaneously evolved with its host over millions of years, the endosymbiotic bacterium Wigglesworthia glossinidia. It provides the insect with nutrients, depends on it the ability of the fly to reproduce. Perhaps this knowledge will someday be used by scientists to prevent the spread of the disease. When bacteria are removed from an insect, scientists can reduce its fertility and, consequently, the transmission of the disease.
The tsetse fly bite is very dangerous. It is a carrier of tiny unicellular organisms of trypanosomes, which are approximately the size of red blood cells. There are several types of parasites, divided into categories according to their effect on vertebrates. Some species do not cause any health problems, while other strains are extremely dangerous. In the process of feeding, an insect acquires them from infected vertebrates and then transfers them to non-infected animals through saliva.
The trypanosome lives in the digestive tract of the insect for several days, after which it moves to the salivary glands. The tsetse fly most likely does not respond to these parasites, but it is quite possible that they increase the chance of insect survival. The fact is that trypanosomes have significantly evolved and formed their own life cycle, which requires a certain time, depending on the owners.
Morphologically, the insect exists in two forms: the larva of the third age stage (when it is separated from the mother) and the adult individual.
The adult fly tsen is a relatively large insect, 0.5 to 1.5 centimeters long, with well-defined characters. It has a large head with a characteristic proboscis, large eyes and unusual antennas that have spines with hairs branched at the ends. The chest is rather large, the abdomen is wide but not elongated, it is shorter than the wings, which have a specific sign in front of them: a segment resembling an ax.