The life cycle of the tsetse fly (1987): Entire title

Summary

Tsetse flies, found only in tropical Africa, are key vectors for diseases caused by trypanosomes, including human sleeping sickness. There are 22 species of tsetse flies, with Glossina morsitans being economically significant. These flies exclusively feed on blood, with some species having specific host preferences. Tsetse flies mate early in life, and females give birth to one larva at a time, nurturing it in their uterus. The larva burrows into the soil and develops into an adult, emerging to find its first blood meal. Understanding their lifecycle and behavior is essential for disease control efforts in sub-Saharan Africa.

Takeaways

• 😀 There are 22 species of tsetse flies, all of which can carry trypanosomes that cause diseases in animals and humans, including sleeping sickness.
• 😀 Tsetse flies are found exclusively in tropical Africa, inhabiting various environments such as rainforests and dry savannah woodlands.
• 😀 Adult tsetse flies range in size from 6 to 14 mm in length and can be distinguished by the pattern of veins in their wings, known as the 'Hatchet cell'.
• 😀 Tsetse flies feed exclusively on blood and their feeding preferences vary between species, with Glossina morsitans favoring warthogs, antelopes, and cattle.
• 😀 Tsetse flies' mouthparts are inserted into the host's tissues, where they break up blood vessels and suck up blood, which causes the fly to swell.
• 😀 Male and female tsetse flies can be differentiated by the presence of a hypopygium, the external genitalia at the end of the abdomen in males.
• 😀 Female tsetse flies mate when young, likely during their first blood meal, and may mate more than once, storing sperm in the spermatheca.
• 😀 Tsetse flies give birth to one living larva at a time, with the larvae feeding on milk produced by the mother's uterine glands.
• 😀 After the egg is fertilized, the larva grows inside the mother, molting twice before being born as a fully-formed maggot, which is highly active and burrows into the soil.
• 😀 The pupal stage lasts about 30 days at 25°C, during which the larva transforms into an adult fly. The adult fly breaks through the puparium and emerges into the soil before seeking its first blood meal.

Q & A

What diseases are transmitted by tsetse flies?

Tsetse flies can carry trypanosomes that cause diseases in animals, including human trypanosomiasis, also known as sleeping sickness.

What is the size range of adult tsetse flies?

Adult tsetse flies measure between 6 to 14 mm in length.

Where are tsetse flies found, and what habitats do they occupy?

Tsetse flies are found only in tropical Africa and can inhabit a range of environments from rainforests to dry savannah woodlands.

How can tsetse flies be distinguished from other flies?

Tsetse flies can be distinguished by the pattern of veins in their wings, forming a characteristic 'hatchet' cell, and they have a prosis that projects forwards.

What is the feeding behavior of tsetse flies?

Tsetse flies feed exclusively on blood. Different species may have varying feeding preferences, with some feeding on animals like warthogs, bush buck, and cattle.

How does a tsetse fly feed on a host?

The fly lowers its tubular mouthparts, which are inserted into the host's tissues. It breaks up tiny capillary blood vessels under the skin to form a pool of blood, which it then sucks up.

How can male and female tsetse flies be differentiated?

Male tsetse flies can be distinguished by the presence of the hypopygium, the external genitalia at the end of their abdomen.

How does mating occur in tsetse flies?

Tsetse fly females typically mate when they are very young, often during their first blood meal. They use a nonvolatile contact sex recognition pheromone to assist in mate selection.

How does fertilization and reproduction work in tsetse flies?

After mating, the male deposits a spermatophore near the female's spermathecal ducts. The sperm moves into the spermatheca, and the female fertilizes an egg which later hatches into a first instar larva.

What is unique about the way tsetse flies give birth?

Unlike most insects that lay large numbers of eggs, tsetse flies give birth to one living larva at a time. The larva is nourished by 'milk' produced by the mother's uterine glands.

What happens during the pupal stage of a tsetse fly?

During the pupal stage, the larva hardens into a puparium, where it undergoes two molts. The adult fly develops inside the puparium, and the process lasts about 30 days at a mean temperature of 25°C.

How do tsetse flies emerge from the puparium?

The adult fly breaks through the puparium using a balloon-like tum on its head, which expands and contracts to help it emerge. The fly then rests while its wings fill with fluid and expand.

What happens after a tsetse fly emerges from the puparium?

After emerging, the fly's wings expand and dry out. It has some residual food reserves from the puparial stage, but it must obtain its first blood meal as soon as possible to continue the cycle.