Anopheles quadrimaculatus is a common mosquito found in the United States, primarily in the eastern half of the country with ranges from the Texas Panhandle to the East Coast. The largest densities of the species are found in the southeastern United States. Anopheles quadrimaculatus is also found in Mexico and southern Canada, including Ontario and Quebec. (La Casse and Carpenter, 1955)
Anopheles quadrimaculatus can be found in many different habitats depending on its stage of life. Larvae are found in freshwater aquatic environments including ponds, swamps and bayous. They can also be found in slow moving canals and streams. Anopheles quadrimaculatus larvae seem to be more prevalent in aquatic environments that contain vegetation and in areas that are exposed to sunlight. Although they are most commonly found in clean water, they are sometimes found in heavily polluted water. Anopheles quadrimaculatus larvae also utilize manmade objects that are filled with water including agricultural ponds and fields, cans, barrels and old tires. Adults are typically found near aquatic habitats. During daylight hours A. quadrimaculatus adults are normally found in sheltered areas. These areas include hollow trees, animal stables and human habitats as well as many other man-made shelters. Anopheles quadrimaculatus adults have been collected at elevations as high as 300 meters. (Boyd, 1949; Foote and Cook, 1959; Horsfall, 1972; La Casse and Carpenter, 1955)
Anopheles quadrimaculatus is a medium sized mosquito that is light brown in color. The tips of the wings lack the copper color seen in many other species. Females have a body length of about 5 mm and wing lengths also near 5 mm. Females also have a long proboscis and labella with small black setae; palpi are the same length as the proboscis. Antennae are filiform and the abdomen is black with many yellow-colored hairs. As in most members of the genus Anopheles, male antennae are more complex than those of females. Male A. quadrimaculatus can be identified by observing their large plumose antennae with long brown hairs that have a yellow luster. Males are also sexually dimorphic in the appearance of their palpi as the last two joints are larger and have many long brown hairs. Males have a body length of 5.5 mm and wing lengths of 4.5 mm. Anopheles quadrimaculatus can be differentiated from other species through the presence of broadly rounded wing scales on the proximal end of the cubitus. The scales of the wings also form four distinct dark spots which makes it fairly easy to distinguish from other Anopheles species. (Boyd, 1949; Dyar, 1928; Headlee, 1945; La Casse and Carpenter, 1955)
Larvae of A. quadrimaculatus have long, rounded heads with single dorsal hairs that are highly branched. The thorax is rounded with short branched hairs and hair tufts. Long feathered hairs are present on the first three abdominal segments. The other abdominal segments have shorter hairs that are less branched. Palmate hairs on the second abdominal segment are also pigmented. Larvae of the genus Anopheles can be distinguished from Culex species by observing the presence or absence of the respiratory siphon located on the rear end. Mosquito larvae of the genus Anopheles do not have siphons while larvae of the genus Culex do. Pupae of Culex and Anopheles show very few differences, although pupae of Anopheles are generally larger. Eggs of A. quadrimaculatus are generally dark in color and more pointed at one end than the other. ("The Mosquitoes of the United States", 1900; Boyd, 1949; Headlee, 1945)
Anopheles quadrimaculatus goes through four stages in its life cycle, progressing through egg, larva and pupa stages to the adult form. Egg, larval and pupal stages all occur in aquatic environments. Developmental times in each stage can vary dramatically depending on the temperatures experienced. Eggs normally hatch within one to three days following oviposition with a mean time of two days; however hatching time can be longer with colder temperatures. Anopheles quadrimaculatus has four larval instars lasting a minimum of twelve days following oviposition with an average of nineteen days under normal conditions. Metamorphosis from larva to adult occurs during the pupal stage, which can last anywhere from two to six days in total with an average of two days, after which fully developed adults emerge. The total life cycle from egg to adult takes a minimum of fourteen days and a maximum of twenty-seven days with a mean of twenty-one days when water temperatures are 74° F. ("Anopheles Mosquitoes", 2008; "Common malaria Mosquito Anopheles quadrimaculatus Say", 2009; Keener, 1945; La Casse and Carpenter, 1955)
Members of Anopheles quadrimaculatus are polygynandrous as both males and females have more than one mate throughout the breeding season. (Boyd, 1949; Horsfall, 1972; Keener, 1945; La Casse and Carpenter, 1955)
Mating occurs near aquatic environments, especially near ponds with vegetation. Female A. quadrimaculatus are sexually mature and able to mate as soon as they emerge from the pupal stage. Sexually mature males typically stay in vegetation and wait for females to emerge from the pupa. As females leave the pupa, males locate them and mating occurs in flight for about ten to fifteen seconds. After mating, females require a blood meal for eggs to become completely mature. The first brood of eggs is normally laid in April or May after blood feeding begins and proper temperature for egg development is reached. Breeding may occur through November, depending on temperatures throughout the breeding season. Eggs are laid on the surface of water in ponds and other aquatic environments and are specially designed to float with a certain orientation on the water’s surface. Females typically oviposit within two to three days after taking a blood meal. Laboratory observations indicated that female A. quadrimaculatus are able to lay nine to twelve broods of eggs during their lifetime, each consisting of 194 to 263 eggs. Once oviposition occurs females are able to breed again immediately, continuing this cycle until the end of their lives. ("Anopheles Mosquitoes", 2008; Horsfall, 1972; Keener, 1945; La Casse and Carpenter, 1955)
After mating and oviposition, Anopheles quadrimaculatus has no additional parental investment in its young.
Females of Anopheles quadrimaculatus typically live much longer than males, averaging about 21 days as compared to about 7 days for males. The maximum lifespan observed of a female is 62 days while the maximum male lifespan is significantly shorter at 22 days. Females that overwinter die immediately following oviposition in the spring. There are many different measurements for the lifespan of these mosquitoes; however they vary significantly depending on conditions and sex. Factors that affect lifespan include temperature and humidity as well as host abundance and the presence of predators. (Horsfall, 1972; Keener, 1945)
Anopheles quadrimaculatus larva lie just below the surface of the water with their body positioned horizontally. If temperatures drop below twelve degrees Celsius, larvae often sink to the bottom of the aquatic habitat and remain there until temperatures warm again. Anopheles quadrimaculatus larvae do not have a breathing siphon; palmate hairs located on the abdomen are used in place of the siphon. Pupae are active but do not feed. They must obtain oxygen from the water’s surface but will move down in the water column if disturbed. Adults are most active during dawn and dusk and normally feed during this time. During the day when not feeding or seeking mates, A. quadrimaculatus spends its time resting in areas that are near the habitats of host species. These habitats may include hollow trees, culverts, homes, and other shaded habitats that allow easy access to blood meals and oviposition sites. Adults are typically solitary, and do not interact often aside from mating. Females overwinter in various sites depending on geographic location. In warmer climates, they overwinter in homes or barns; in cooler climates females overwinter in isolated areas including storm drains and caves. Females mate before overwintering, thus they are able to oviposit once early in the spring, but typically die afterward. ("Common malaria Mosquito Anopheles quadrimaculatus Say", 2009; Boyd, 1949; Horsfall, 1972; La Casse and Carpenter, 1955)
Anopheles quadrimaculatus has been observed to have a flight range of about 1.6 km, with the majority of adults staying near the breeding site. When host species are limited adults can increase their range with a maximum of about 4 km. Some adults have been observed to stay within 0.25 km or less. Densities typically decline with increased distance from hatching sites. Adults may stay in the same area for long periods of time, often returning to the same host to feed throughout their lives. Males typically stay closer to the breeding site while females have been observed to remain close to the breeding site for less time and later disperse following oviposition. (Boyd, 1949; Eyles, et al., 1945; Horsfall, 1972; Le Prince and Griffitts, 1917)
Anopheles quadrimaculatus is able to communicate through very distinct but low energy sounds. Females produce sounds with higher energy than males; however both sexes appear to have similar sounds for mating, alerting of danger, or anger. Many males will respond to the mating call of a single female with the sounds being picked up by their antennae. These sounds are made in a variety of ways including beating of the wings and rubbing the tarsi against the wings. As in other mosquito species, A. quadrimaculatus finds hosts through olfactory receptors and are attracted by carbon dioxide and ammonia as well as other odors. Maxillary palps are able to detect carbon dioxide while antennae are able to detect host odors. Anopheles quadrimaculatus may be particularly sensitive to carbon dioxide as it often bites humans on their heads. It is believed that each species uses specific odors to locate their hosts, however little information exists on this topic. Studies have also shown that these mosquitoes are also attracted by the heat and moisture of their hosts. (Dekker, et al., 1998; Enserink, 2002; Kahn, et al., 1945)
Larvae of Anopheles quadrimaculatus feed on food particles that are within one to two meters from the surface of the water. Observations indicate that larvae feed on many different aquatic organisms and seem to have no preference for what they consume. The only requirement for the food is the size, however if the food particles are too large they may macerate them before consumption. Filamentous algae is typically macerated by running the food across the mandibles while consuming particles that break off. The maximum food particle size increases with each larval instar ranging from 37 microns to 131 microns. In natural habitats larvae typically feed on detritus, plankton, and filamentous algae. Larvae have been kept alive through development in the laboratory by feeding only yeast, algae, broken hay or ground dog biscuits.
Adults of A. quadrimaculatus have different feeding patterns, depending on the sex. Both males and females feed on many different species of plants for sugars and nectar. Laboratory experiments show that both species can be kept alive by feeding glucose, honey or other sugar syrups. To produce eggs females must feed on blood. They will feed on many animals including humans, cows, horses, pigs, sheep, dogs, cats and also some birds. Many observations have been made on blood feeding of A. quadrimaculatus and there have been mixed results on the preferred host and the amount of feeding on human hosts as the hosts available depend on the habitat of the mosquito. Adults typically feed from dusk until sunrise; however they will feed during the day if hosts are readily available. Feeding times can vary depending on host species as well as environmental conditions. The mouth parts of the females are specially designed for blood feeding through solenophagy. They are able to use a special anti-coagulant that is very powerful, even in 1:10,000 or greater dilutions, to assist in feeding. This anti-coagulant is introduced into the blood before the mosquito feeds, in order to prevent the blood from solidifying inside of the mosquito. ("Common malaria Mosquito Anopheles quadrimaculatus Say", 2009; Boyd, 1949; Horsfall, 1972; Keener, 1945; Metcalf, 1945)
There are many different predators of mosquitoes, however few specific species of predators of Anopheles quadrimaculatus have been named. In general many species of birds and bats are known to feed primarily on adult mosquitoes. Larvae and pupae are commonly eaten by many different predators including carnivorous insects, as well as many species of fish and aquatic fowl. When water levels decrease and larvae and pupae are stranded on land, other insects such as shore bugs as well as many species of ants will feed on them. (Horsfall, 1972)
The primary ecosystem role of Anopheles quadrimaculatus seems to be its role as a vector for various diseases. It is the most important vector of malaria in the United States as it is a competent vector of Plasmodium falciparum, Plasmodium vivax and Plasmodium malariae. Other important human diseases can also be transmitted by A. quadrimaculatus including Cache Valley virus and West Nile virus. In lab studies it has also been shown to be a vector for St. Louis encephalitis. It is also a very common vector of heartworms, Dirofilaria immitis. At least three species of Plasmodium are also transmitted to birds through A. quadrimaculatus, however the rate of infection is undetermined. Aside from its role as a disease vector, A. quadrimaculatus larvae are a common source of food for many aquatic insects such as shore bugs as well as many species of ants, fish and ducks. Adults are also a common source of food for many species of birds and bats, however specific examples are unknown. Anopheles quadrimaculatus adult females are temporary ectoparasites of many vertebrates including cattle, horses, pigs, birds, humans, and domestic cats and dogs. ("Anopheles Mosquitoes", 2008; Horsfall, 1972; Keener, 1945; La Casse and Carpenter, 1955)
There are no known positive effects of Anopheles quadrimaculatus on humans.
The largest and most studied negative effect of Anopheles quadrimaculatus on humans is its role as the primary vector of malaria in the United States. Anopheles quadrimaculatus serves as the primary vector of the most pathogenic agent of malaria, Plasmodium falciparum as well as the less pathogenic strains of Plasmodium vivax and Plasmodium malariae. Although a competent vector exists, malaria has not been a major problem in the United States since the 1940’s. Since 1957, 63 outbreaks have occurred in the United States, causing 156 cases that were a result of mosquito transmission. Around 1,500 cases of malaria are reported in the United States each year however most are acquired outside of the United States. Due to increased global travel and the large presence of A. quadrimaculatus as a vector there is the potential for more widespread and severe outbreaks of malaria in the United States. The Centers for Disease Control and Prevention as well as state and local health departments monitor cases of malaria carefully and have many control measures in place. ("Anopheles Mosquitoes", 2008; "Common malaria Mosquito Anopheles quadrimaculatus Say", 2009; "Locally Acquired Mosquito-Transmitted Malaria: A Guide for Investigations in the United States", 2006; Boyd, 1949; Headlee, 1945)
Anopheles quadrimaculatus is also a vector for other human diseases including Cache Valley virus. Cache Valley virus is rarely diagnosed in the United States, however it has been observed most commonly in A. quadrimaculatus. It is not yet known if this mosquito is the primary vector in the United States. This mosquito also vectors West Nile virus, which can cause death in humans as well as many other species including birds, dogs, cats, and horses. In 2009 there were 663 cases reported in the United States, with 30 resulting in death. Since A. quadrimaculatus and many other mosquitoes are vectors of several human diseases, many efforts have been taken to reduce their population through the removal of breeding habitats (stagnant water) and the use of insecticides. Anopheles quadrimaculatus is also a common vector of Dirofilaria immitis which is the agent causing heart worm in dogs and cats. This disease can cause serious harm to these household pets and a great deal of money can be spent on preventive measures and treatments. ("CDC West Nile Virus Homepage", 2009; "Common malaria Mosquito Anopheles quadrimaculatus Say", 2009; "Mosquito-borne Dog Heartworm Disease", 1990; Campbell, et al., 2006; Horsfall, 1972)
Anopheles quadrimaculatus populations are large throughout its wide geographical range and do not appear to be in danger of declining in the future. Any efforts to control population numbers are focused solely on reducing their numbers as they are primary vectors of disease.
Paul Glyshaw (author), University of Michigan-Ann Arbor, Heidi Liere (editor), University of Michigan-Ann Arbor, John Marino (editor), University of Michigan-Ann Arbor, Barry OConnor (editor), University of Michigan-Ann Arbor, Rachelle Sterling (editor), Special Projects.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
living in landscapes dominated by human agriculture.
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.
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.
areas with salty water, usually in coastal marshes and estuaries.
an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).
either directly causes, or indirectly transmits, a disease to a domestic animal
uses smells or other chemicals to communicate
active at dawn and dusk
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
mainly lives in water that is not salty.
An animal that eats mainly plants or parts of plants.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
(as keyword in perception channel section) This animal has a special ability to detect heat from other organisms in its environment.
fertilization takes place within the female's body
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).
marshes are wetland areas often dominated by grasses and reeds.
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.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats nectar from flowers
active during the night
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
living in residential areas on the outskirts of large cities or towns.
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
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).
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
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.
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.
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.
living in cities and large towns, landscapes dominated by human structures and activity.
uses sight to communicate
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