About Opentopia
Opentopia Directory Encyclopedia Tools

Triatominae

Encyclopedia : T : TR : TRI : Triatominae

 

Triatominae is a subfamily of Reduviidae, order Heteroptera; also known as conenose bugs, assassin bugs or kissing bugs. All the ~130 species of this group are haematophageous, i.e. feed on vertebrate blood. They are mainly widespread in America, with some few species in Asia, Africa and Australia. These bugs usually share shelter with nesting vertebrates, from which they suck blood.

All triatomine species are potential vectors of Chagas disease but, only those species (such as Triatoma infestans and Rhodnius prolixus) that are well adapted to live with humans are considered important vectors of the Chagas disease parasite (i.e. Trypanosoma cruzi).

In 1909 the Brazilian doctor Carlos Chagas discovered that these insects were responsible for the transmission of T. cruzi to many of his patients, as he put it in words: "Knowing the domiciliary habits of the insect, and its abundance in all the human habitations of the region, we immediately stayed on, interested in finding out the exact biology of the barbeiro, and the transmission of some parasite to man or to another vertebrate.

Herman Lent, who after being student of Carlos Chagas became devoted to the study of the triatomines, together with Peter Wygodzinsky, made a revision work of the Triatominae that was published in the Bulletin of the American Museum of Natural History (New York), 163 (3):125-520, figures 1-320, 1979, a summary of his 40 years of studies on the triatomines up to that time.

The main vectors of Chagas disease are:

Contents

Description by Charles Darwin

Description from Charles Darwin's Journal and Remarks, commonly known as The Voyage of the Beagle; Extract from entry for 25 March 1835:

"We crossed the Luxan, which is a river of considerable size, though its course towards the sea-coast is very imperfectly known: it is even doubtful whether, in passing over the plains, it is not evaporated and lost. We slept in the village of Luxan, which is a small place surrounded by gardens, and forms the most southern cultivated district in the Province of Mendoza; it is five leagues south of the capital. At night I experienced an attack (for it deserves no less a name) of the Benchuca, a species of Reduvius, the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over one's body. Before sucking they are quite thin, but afterwards they become round and bloated with blood, and in this state are easily crushed. One which I caught at Iquique, (for they are found in Chile and Peru,) was very empty. When placed on a table, and though surrounded by people, if a finger was presented, the bold insect would immediately protrude its sucker, make a charge, and if allowed, draw blood. No pain was caused by the wound. It was curious to watch its body during the act of sucking, as in less than ten minutes it changed from being as flat as a wafer to a globular form. This one feast, for which the benchuca was indebted to one of the officers, kept it fat during four whole months; but, after the first fortnight, it was quite ready to have another suck."

Aspects

Triatomines are haematophagous insects: all five triatomine nymph instars and adults require blood to survive. They also require the stability of a sheltered environment. Most species are associated with wild nesting vertebrates and are named "sylvatic" triatomines. These live in ground burrows with rodents or armadillos, or in tree-dwellings with bats, birds, sloths or opossums. Few species (5%) live in human dwellings or in the surrundings of human houses (peridomicile), near the shelters of domestic animals; these are named "domestic" species. Domestic and sylvatic species carry the Chagas parasite to humans and wild mammals, respectively. Birds are immune to the parasite. Many sylvatic species are in process of domiciliation ("semidomestic").

Rhodnius prolixus nymphs and adult
Enlarge
Rhodnius prolixus nymphs and adult

Chagas transmission is carried mainly from human to human by domestic kissing bugs. T. cruzi parasite is transmited from the vertebrate to the bug by blood, and from the bug to the vertebrate by the insect's faeces and not by its saliva, as occurs in most bloodsucking arthropod vectors such as Malaria mosquitoes.

Triatomine infestation specially affects poor people. One can recognize the presence of triatomines in a house by its faeces. Triatomines characteristically leave 2 kinds of feces like strikes on walls of infected houses, one is white with uric acid, the other is dark (black) containing haem. Whitish eggs can be seen in crevices of the wall.

(After having had a blood meal the insects sometimes show a limited mobility, as they are found resting on walls, probably incapable to fly...)

Tribes, Genera and numbers of described species

fat: containing species are possibly able to transmit Trypanosoma cruzi to humans (Chagas).

Total Number of Triatominae species: 137.

The number of species which are suspected or have shown to be able to transmit Trypanosoma cruzi: 79;

47 of these belong to the genus Triatoma.

note: Taxonomy is changing due to new research, e.g. see:

References

See also

External links

Google picture search

The pictures will give an overview of the main morphology of the main vectors. Today, other species could be also important for the transmission of chagas disease. Some of the pictures could be "open source" also and should be considered to be included in wikipedia (!).

Other

 

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.

Search Titles
0123456789
ABCDEFGHIJ
KLMNOPQRST
UVWXYZ?

E-mail this article to:

Personal Message: