Taxonomic name: Anopheles quadrimaculatus Say, 1824
Synonyms: Anopheles annulimanus Wulp, 1867
Common names: common malaria mosquito (English), common malaria mosquito, Gabelmücke (German)
Organism type: insect Anopheles quadrimaculatus is the chief vector of malaria in North America. This species prefers habitats with well-developed beds of submergent, floating leaf or emergent aquatic vegetation. Larvae are typically found in sites with abundant rooted aquatic vegetation, such as rice fields and adjacent irrigation ditches, freshwater marshes and the vegetated margins of lakes, ponds and reservoirs. Description
Anopheles quadrimaculatus is described as a large, dark brown mosquito. The tarsus is entirely dark (The Ohio State University Mosquito Pest Management Bulletin,1998). O'Malley (1992) reports that, "all Anopheles adults are characterised by an evenly rounded scutellum and palpi about as long as the proboscis. A. quadrimaculatus is a medium-sized species. Wings are entirely dark scaled and 4mm or more in length. Scutal bristles are short and wings are spotted with patches of dark scales. The palpi have dark scales and are unbanded and the wing has 4 distinct dark-scaled spots .." Rafferty et al. (2002) found, "a simple method for rapid identification of large numbers of Anopheles mosquitoes, based on polymerase chain reaction (PCR) amplification of rDNA." The authors state that, "This method allows rapid analysis of large numbers of mosquitoes without robotic equipment and should enable rapid and extensive PCR analysis of field-collected samples and laboratory specimens." Similar Species
Anopheles diluvialis, Anopheles inundatus, Anopheles maverlius, Anopheles smaragdinus
More
Occurs in:
lakes, riparian zones, urban areas, water courses, wetlands Habitat description
Chase and Knight (2003) state that, "Many species of mosquitoes are habitat generalists which breed, grow as larvae and emerge from a wide variety of aquatic habitats ." O'Malley (1992) reports that, "In North America, most anophelines prefer habitats with well-developed beds of submergent, floating leaf or emergent aquatic vegetation. Larvae are typically found in sites with abundant rooted aquatic vegetation, such as rice fields and adjacent irrigation ditches, freshwater marshes and the vegetated margins of lakes, ponds and reservoirs. Investigators have suggested that aquatic vegetation promotes anopheline production as it provides a refuge for larvae from predators, such as Gambusia affinis. Additional hypotheses for the beneficial effects of aquatic vegetation include: enhanced food resources in vegetated regions, shelter from physical disturbance and favourable conditions for oviposition (Orr and Resh 1989)." Comparing and contrasting different mosquito species, Chase and Knight (2003) state that, "Although these species have somewhat distinct habitat preferences, they readily lay eggs in, and emerge from, wetlands of all types (Carpenter & LaCasse 1955). Although A. quadrimaculatus will also breed in smaller water-filled habitats (e.g. containers, ditches), which are often associated with humans, wetlands provide a much greater area for potential larval habitats, and often produce many more adult mosquitoes, than the smaller habitats traditionally associated with mosquito control." The Ohio State University Mosquito Pest Management Bulletin (1998) reports that, "These mosquitoes breed chiefly in permanent freshwater pools, ponds and swamps that contain aquatic vegetation or floating debris. Common habitats include borrow pits, sloughs, city park ponds, sluggish streams and shallow margins of reservoirs and lakes. During the daytime, adults remain inactive, resting in cool, damp, dark shelters such as buildings and caves." General impacts
O'Malley (1992) comments that the concern about Anopheles quadrimaculatus "is due primarily to the fact that it is the chief vector of malaria in the eastern, central and southern United States." Anopheles quadrimaculatus is susceptible to infection with Plasmodium falciparum, Plasmodium vivax and Plasmodium malariae (Carpenter and LaCasse 1955). In addition to malaria, transmission of St. Louis encephalitis has been obtained with this species in laboratory experiments (Horsfall 1972). A. quadrimaculatus has been found to be an excellent host for Dirofilaria immitis. According to Lewandowski et al. (1980), this is probably one of the most important species involved in the natural transmission of dog heartworm in Michigan. In central New York, this species was also the most efficient host of dog heartworm out of several species tested, both in the laboratory and the wild (Todaro and Morris 1975). The Ohio State University Mosquito Pest Management Bulletin (1998) reports that, A. quadrimaculatus is the most important vector of malaria the eastern United States. The bites are less painful than many other mosquitoes and often go unnoticed.A. quadrimaculatus can be a vector for the myositic parasite Trachipleistophora hominis. Weidner et al. (1999) found that, "Microsporidian spores of T. hominis Hollister, isolated from a human, readily infected larval stages of both A. quadrimaculatus." The authors state that, "Nearly 50% of the infected mosquito larvae survived to the adult stage. Spores recovered from adult mosquitoes were inoculated into mice and resulted in significant muscle infection at the site of injection." Blackmore et al. (1998) found that A. quadrimaculatus can transmit the Cache Valley virus (CV). The results of their study suggest that A. quadrimaculatus could be involved in the midwestern United State's transmission cycle of the virus. A study conducted by Milam et al. (2000) found that exposure to as much as 31.4 mug/L of seven typical A. quadrimaculatus was required for effective control, but that as little as 2.7 mug/L resulted in substantial mortality of some non-target organisms. The authors state that, "These data suggest that prevailing application rates for effective mosquito control not only affect nontarget organisms but may also confound stormwater and nonpoint toxicity evaluations that utilise sensitive indicator species." Contrary to current research, Chase and Knight (2003) found that, "Mosquito density increased dramatically following a natural drought event in a survey of wetlands, and after an experimental drought event in outdoor mesocosms intended to mimic many features of natural wetlands. These patterns are consistent with our hypothesis that predators and competitors limit mosquito populations in permanent and temporary wetlands, respectively, whereas in semi-permanent wetlands, mosquito densities can outbreak following drought years because of the loss of both these groups of interactors. The reason this occurs is most likely because these mosquitoes are habitat generalists and opportunists, and following a drought event, they can quickly re-colonise these wetlands." Notes
Levine et al. (2004) report that, "Anopheles quadrimaculatus was considered to be a single species until biological evidence necessitated subdividsion into a species complex in the late 1900s. A combination of genetic crossing, isozyme and ctytological information convincingly showed that there are at least five species in the group and they include: A. quadrimaculatus, A. smaragdinus, A. diluvialis, A. inundatus, and A. maverlius." The authors also state that Anophelse quadrimaculatus is the most widely distributed of the species complex in the eastern United States and southeastern Canada (Seawright et al. 1991)." In the United States, Anopheles quadrimaculatus is a cleanwater-loving mosquito. Current wetland regulations could be seen as possibly impeding efforts to control the mosquito, by improving water quality within water management project sites (O'Malley, 1992). Geographical range
Native range: North America; Anopheles quadrimaculatus has a distribution that covers much of the eastern United States. Its range extends from southern Canada to the Florida Everglades, and to the west from Minnesota to Mexico (Kaiser, 1994). Please follow this link for a distribution map (Levine et al. 2004). Nutrition
Anopheles quadrimaculatus larvae are indiscriminate feeders. Their natural food includes a wide range of aquatic organisms, both plant, animal and detritus. Food may be alive or dead at the time of ingestion. The main criterion in selecting food seems to be whether the suspended material is small enough to eat. When feeding, A. quadrimaculatus larvae lie horizontally, with the dorsal side just under the water surface film. The head then rotates 180 degrees until it is upside down and the venter of the head is dorsal. Feeding is either "eddy feeding" or "interfacial feeding". Eddy feeding is employed for infusions when the surface contains islets of floating oil materials. Two eddies with converging streams unite in front of the larva to form a current towards the mouth of the mosquito from a distance of about half the length of the larva. Efferent currents flow outward at right angles to the body from the antenna. Particles which are too large to eat are held by the maxillae, drawn below the surface and discarded as the head is rotated to the normal position. Interfacial feeding on the membranes of algae, bacteria, debris and fungi is common in nature. Feeding in this manner is accomplished by setting up currents which draw particles to the mouth in a straight line and at nearly equal velocities. Surface tension of the larval habitat determines the type of feeding. Eddy feeding occurs at a surface tension of less than 60 dynes per square cm; interfacial feeding is practiced in habitats with a surface tension above 62 dynes per square centimetre. Mosquito feeding patterns are largely regulated by host availability and preference (Apperson and Lanzaro 1991). Female Anopheles quadrimaculatus are primarily mammalian feeders and actively feed on humans as well as animals. Females repeatedly seek hosts; often visiting the same feeding site several times during the course of a blood meal (O'Malley, 1992).Larvae of the two most common mosquito species in natural and artificial wetlands, Anopheles quadrimaculatus and C. pipiens, (plus other types of mosquito larvae) utilise different feeding behaviours and have slightly different diets (e.g. Merritt et al. 1992). Both of the mosquitos are generalists and readily consume detritus, microbes and algae. As such, they are likely to compete for resources with several other co-occurring species. (Chase and Knight, 2003) Reproduction
The Ohio State University Mosquito Pest Management Bulletin (1998) reports that, "Anopheles quadrimaculatus eggs are laid singly on the water surface with lateral floats to keep them at the surface. One hundred or more eggs are laid at a time. A single female may lay as many as 12 batches of eggs and a total of more than 3,000 eggs." O'Malley (1992) reports that, "Mating occurs as soon as the females emerge. Males wait in nearby vegetation and seek females as they begin to fly. Copulation is completed in flight and takes 10-15 seconds. One insemination is usually sufficient for the fertilisation of all eggs." Lifecycle stages
Floore (2004) states that, "The mosquito goes through four separate and distinct stages of its life cycle: egg, larva, pupa and adult. Each of these stages can be easily recognised by its special appearance." Egg stage: Eggs are laid one at a time or attached together to form "rafts." They float on the surface of the water and in the case of Culex and Culiseta species, the eggs are stuck together in rafts of up to 200. Anopheles, Ochlerotatus and Aedes, as well as many other genera, do not make egg rafts, but lay their eggs singly. Culex, Culiseta and Anopheles lay their eggs on the water surface while many Aedes and Ochlerotatus lay their eggs on damp soil that will be flooded by water. Most eggs hatch into larvae within 48 hours; others might withstand subzero winters before hatching. Water is a necessary part of their habitat. Larval stage: The larva (plural - larvae) lives in the water and comes to the surface to breathe. Larvae shed (molt) their skins four times, growing larger after each molt. Most mosquito larvae have siphon tubes for breathing and hang upside down from the water surface, however Anopheles larvae do not have a siphon and lie parallel to the water surface to get a supply of oxygen through a breathing opening. Coquillettidia and Mansonia larvae attach to plants to obtain their air supply. The larvae feed on microorganisms and organic matter in the water. During the fourth molt the larva changes into a pupa (Floore, 2004). Pupal stage: The pupal stage is a resting, non-feeding stage of development, but pupae are mobile, responding to light changes and moving (tumble) with a flip of their tails. This is the time the mosquito changes into an adult. The process is similar to the metamorphosis seen in butterflies. In Culex species in the southern United States this process takes about two days in the summer. When development is complete, the pupal skin splits and the adult mosquito (imago) emerges (Floore, 2004). Adult:: The newly emerged adult rests on the surface of the water for a short time to allow itself to dry and all its body parts to harden. The wings have to spread out and dry properly before it can fly. Blood feeding and mating does not occur until a couple of days after the adults emerge (Floore, 2004). This species has been nominated as among 100 of the "World's Worst" invaders Reviewed by: Major update under progress Principal sources: Shiff, 2002. Integrated Approach to Malaria Control
Levine et al. 2003. Distribution of Members of Anopheles quadrimaculatus Say s.l. (Diptera: Culicidae) and Implications for Their Roles in Malaria Transmission in the United States.
Compiled by: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
|
|
Last Modified: Thursday, 23 March 2006
|
