Geographic Range
The
Anopheles gambiae
complex is widely distributed throughout Africa.
Habitat
Individuals live throughout Africa, as long as water is readily available. Some species
prefer fresh water, while others within the
Anopheles gambiae
complex live near water with high saline concentrations.
- Habitat Regions
- temperate
- tropical
- terrestrial
- saltwater or marine
- freshwater
- Terrestrial Biomes
- savanna or grassland
- forest
- scrub forest
- Aquatic Biomes
- lakes and ponds
- rivers and streams
- temporary pools
- brackish water
- Other Habitat Features
- urban
- suburban
- agricultural
- riparian
- estuarine
Physical Description
Mosquitoes, like all insects, have three body segments: a head, thorax, and abdomen.
The thoracic segment possesses three pairs of legs and a pair of wings used for flight.
The hind wings are modified into balancing appendages called halteres. Male antennae
have significantly more hair like structures, called setae, which aid in locating
females.
The general coloration of this species is yellowish brown to brown with the last segment
of the body normally all dark. The legs are spotted or speckled as an adult, and
females normally have three pale bands on their palpi. The wings have pale scales
that are creamy white and tinged with yellow.
Anopheles gambiae
larvae are 5-6 mm long and they are colored in much the same manner as the muddy
water in which they are found. They breathe underwater through posterior spiracular
plates on the 8th abdominal segment.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes colored or patterned differently
Development
Anopheles gambiae
development is holometabolous, with four larval instar stages followed by a non-feeding
pupal stage where the organism undergoes complete metamorphosis from the larval form
to the adult morphology.
All mosquito larvae and pupae are aquatic. The larvae eat small pieces of organic
matter, while the pupae eat nothing and do not move.
- Development - Life Cycle
- metamorphosis
Reproduction
Adults mate almost immediately after emerging.
Adults mate soon after emerging from their pupae. Females require blood meals to
mature their fertilized eggs. Some species in the
Anopheles gambiae
complex are freshwater breeders while others prefer saltwater, but mosquito eggs
must remain in contact with water to survive. Females lay their eggs singly on the
surface of the water, up to 200 eggs at a time. The presence of water is necessary
for the development of the eggs and larvae. Some species in the
Anopheles gambiae
complex prefer small, shaded pools and rice fields to lay their eggs, while others
prefer water with a high salinity concentration. Despite the site preference, the
pools of water are almost always exposed to direct sunlight.
- Key Reproductive Features
- iteroparous
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- oviparous
Behavior
When at rest, Anopheles gambiae larvae float horizontally beneath the water's surface. The larvae breathe underwater through posterior spiracular plates on the 8th abdominal segment instead of through an air tube. This feature allows larvae to remain submerged underwater with only a small portion of their body exposed to the air.
Anopheles gambiae is especially adept at breeding in areas created by humans. After taking a blood meal, females often rest on nearby walls within the human host's residence. This behavior may provide an opportunity to eradicate this species from villages and homes in Africa through residual insecticide use.
In addition, adults in the genus
Anopheles
have a distinctive resting and feeding posture. While at rest, the head, mouth and
abdomen are nearly in a straight line, but when feeding the body is inclined at a
sharp angle to the host's body.
Communication and Perception
Females locate their hosts using a variety of sensory receptors, but respond to movement,
carbon dioxide gradients, and sweat. Also, two odorant-binding proteins (OBP) have
been isolated in
Anopheles gambiae
, which are hypothesized to aid female's search for human hosts.
Food Habits
All
Anopheles gambiae
females are temporary ectoparasites, living in the environment and coming to the
host to feed. The females require blood meals to mature their eggs. Males, however,
are non-parasitic and feed on plant fluids. Females do not display a tremendous amount
of host specificity, but research indicates
Anopheles gambiae
preferentially feeds on humans. Females locate their hosts using a variety of sensory
receptors, but respond to movement, carbon dioxide gradients, and sweat. Also, two
odorant-binding proteins (OBP) have been isolated in
Anopheles gambiae
, which are hypothesized to aid female's search for human hosts.
- Primary Diet
- carnivore
-
herbivore
- nectarivore
- eats sap or other plant foods
- Animal Foods
- blood
- Plant Foods
- nectar
- sap or other plant fluids
Predation
Mosquitos are food for many types of birds, bats, frogs, lizards, and spiders.
Ecosystem Roles
These mosquitoes are disease vectors, and also provide food to predators.
- Ecosystem Impact
- parasite
Economic Importance for Humans: Positive
Anopheles gambiae have no known positive economic impact on humans.
Economic Importance for Humans: Negative
In the United States, mosquitoes are often thought of as a pest and a nuisance.
Anopheles gambiae
is much more than a simple pest, it is responsible for the transmission of malaria
and other serious diseases throughout Africa.
Anopheles gambiae
transmits
Plasmodium falciparum
, which is the most severe of the four malarial agents. Although this disease was
wiped out in the United States, it remains a world health hazard. There are an estimated
300 to 500 million cases of malaria each year and as a result, 1.5 to 2.7 million
deaths worldwide. Continental sub-Sahara Africa, however, accounts for roughly 90%
of all malarial cases worldwide.
- Negative Impacts
-
injures humans
- bites or stings
- carries human disease
- household pest
Conservation Status
Other Comments
Anopheles gambiae is not a single mosquito species, but instead a species complex comprising six species that are morphologically similar but reproductively isolated.
An average person in Africa may experience 50 to 100
Anopheles gambiae
bites per night.
Additional Links
Contributors
Sara Diamond (editor), Animal Diversity Web.
Matthew Wund (editor), University of Michigan-Ann Arbor.
Jason Prior (author), University of Michigan-Ann Arbor, Solomon David (editor), University of Michigan-Ann Arbor.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- terrestrial
-
Living on the ground.
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- freshwater
-
mainly lives in water that is not salty.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- brackish water
-
areas with salty water, usually in coastal marshes and estuaries.
- marsh
-
marshes are wetland areas often dominated by grasses and reeds.
- swamp
-
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
- bog
-
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
- urban
-
living in cities and large towns, landscapes dominated by human structures and activity.
- suburban
-
living in residential areas on the outskirts of large cities or towns.
- agricultural
-
living in landscapes dominated by human agriculture.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- estuarine
-
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- metamorphosis
-
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- internal fertilization
-
fertilization takes place within the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- parasite
-
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
- motile
-
having the capacity to move from one place to another.
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- chemical
-
uses smells or other chemicals to communicate
- parasite
-
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
- carnivore
-
an animal that mainly eats meat
- sanguivore
-
an animal that mainly eats blood
- herbivore
-
An animal that eats mainly plants or parts of plants.
- nectarivore
-
an animal that mainly eats nectar from flowers
References
Blackwell, A., S. Johnson. June, 2000. Electrophysiological investigation of larval water and potential oviposition chemo-attractants for Anopheles gambiae s.s.. Annals of Tropical Medicine and Parasitology , 94(4): 389-398.
Comstock, J. 1920. Introduction to Entomology . United States: The Comstock Publishing Company.
Evans, A. 1938. Mosquitoes of the Ethiopian Region . London: Oxford University Press.
Konate, L., O. Faye, O. Gaye, M. Diouf, A. Diop. September, 1999. Observations on the feeding patterns and the alternative hosts selection of the malaria vectors in Senegal. Parasite , 6(3): 257-267.
Meijerink, J., M. Braks, A. Brack, W. Adam, T. Dekker. June, 2000. Identification of olfactory stimulants for Anopheles gambiae from human sweat samples. Journal of Chemical Ecology , 26(6): 1367-1382.
Nchinda, T. 1998. "Centers for Disease Control and Prevention" (On-line). Accessed 12/15/04 at http://www.cdc.gov/ncidod/eid/vol4no3/nchinda.htm .
Roberts, L., J. Janovy, Jr.. 2000. Foundations of Parasitology sixth edition . United States: McGraw-Hill Companies.
2004. "World Health Organization" (On-line). Accessed 12/15/04 at http://www.who.int/tdr/research/progress/mal_str/default.htm .