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SANDFLIES (Psychodidae) Sandfly
Fevers (Contact) Please
CLICK on
Image & underlined links for details: There are
some medically important species that are vectors of various fevers, such as Leishmania, Pappataci fever,
Kala-azar
and Oroya fever,
especially in tropical regions.
Service (2008) reported that there are almost 1,000 species in six
genera. Those that draw blood from
vertebrates are in the genera Phlebotomus,
Lutzomyia and Sergentomyia. Phelobotomus
species are absent from the Americas but range in parts of Africa and
Asia. They typically are active in
drier savannas. Lutzomyia are restricted to the
Americas where they are abundant in the forests of Central and South
America. Sergentomyia species also are not found in the Americas
but rather Central Africa and Asia.
However, they do not generally encounter humans and are not
vectors. Service (2008) listed the
most medically important species are Phelebotomus
papatasi, P. sergenti, P.
argentipes, P. ariasi, P. perniciousus and Lutzomyia longipalpis and L. flaviscutellata. In addition
to Leismaniasis, sandflies are
involved as vectors of other diseases affecting humans. Bartoneliosis
is a disease found in mountainous areas of the Andes of South America. It is caused by Barionella bacilliformis and vectored by Lutzomyia
verrucarum, L. colombiana and other Lutzomyia species. There are
also seven viral serotypes of sandfly fever, often called "Papataci Fever." They occur in the Mediterranean region but
extend into Egypt and India and possibly China. The principal vector is Phlebotomus
papatasi. Other forms
of the virus occur in Central and South America, vectored by Lutzomyia trapidoi and
others of the genus. Female sandflies
become infective about a week after a blood meal. Eggs containing the virus are laid which give rise to infected
adults. Various mammals are suspected
as reservoir hosts. CHARACTERISTICS & DEVELOPMENT The moth flies and sand flies have abundant scales on
their wings. They are small to very
tiny insects with a large number of hairs on their bodies. When at rest adults may hold their wings
roof like over the body. The habitat
is in moist shady areas but can also be found in drainages or sewers. Adults may occur in bathrooms that they
enter via sink drains. Larvae inhabit
decaying vegetable matter, moss, mud or water. Oviposition
is not directly in water but occurs in ground holes, termite mounds, masonary
cracks in poultry houses and around the roots of forest trees, etc. (Service
2008). The larvae feed as scavengers
on organic matter and rotting vegetation.
The genus Phlebotomus
occurs in partially arid areas, but their larvae still develop in a high
humidity environment. Larvae pass
through 4 instars in about 20-30 days, which of course varies with
temperature and different species.
The 4th instar larva may go into diapause if conditions are
unfavorable. Overwintering is in the
larval state in colder climatic areas. Adults feed
on plant sap and other sweet secretions, but the females draw blood from
vertebrates. Lutzomyia species restricted to the
Americas and Phlebotomus
species elsewhere attack humans and other mammals. They are all especially active during sunset and at night and in
outdoor darkened environments, such as forests. Most species require blood meals to lay viable eggs, but a few
autogenous species lay viable eggs without a blood meal. All adults are weak fliers and will not
spread far from their breeding sites, but windy conditions can drive them
greater distances. Other adult
behaviors are noted by Service (2008). CONTROL Insecticide
control of vector sandflies is effective until resistance sets into the fly
population. Therefore, the use of
repellants is preferable. To reduce
diseases caused by sandflies some efforts have been made to eliminate
reservoir hosts from populated areas.
Further efforts to control the vectors remain experimental, especially
as the breeding sites of most sandflies are not easily found. = = = = = = = = = = = =
= = = = = = = = Key References:
<medvet.ref.htm> <Hexapoda> Adler, P. H., D. C. Currie & D. M. Wood. 2004.
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Control of phlebotomine sandflies.
Med. & Veterinary Entomology 17:
1-18. Ashford, R. W. 2001.
Leishmaniasis. 2001. IN:
Encylopedia of Arthropod Transmitted Infections of Man &
Domesticated Animals. CABI pp. 269-79. Boatin, B. A. & F. O. Richards. 2006.
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