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| Culicinae | |
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| Culiseta longiareolata | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Diptera |
| Family: | Culicidae |
| Subfamily: | Culicinae |
TheCulicinae are the most extensive subfamily ofmosquitoes (Culicidae) and havespecies in every continent except Antarctica, but are highly concentrated in tropical areas. Mosquitoes are best known asparasites to manyvertebrate animals andvectors fordisease. They areholometabolousinsects, and most species lay theireggs in stagnant water, to benefit their aquatic larval stage.
Thesubfamily Culicinae is the largest subfamily ofCulicidae, afamily ofNematoceradipterans. There are 3,046 species of Culicinae mosquitoes, in 108genera and 11 tribes. Members of the Culicinae subfamily are small flies with fore wings for flight and hind wings reduced tohalteres for balance. The mosquitoes also have long, slender, legs andproboscis-style mouth parts for feeding on vertebrate blood or plant fluids. Only the females are blood feeders, requiring a high quality protein meal before they canoviposit. Because the mosquitoes are well adapted for finding hosts, the females can move quickly from one blood meal to another, and when injecting their saliva, can inject pathogens picked up from other hosts and thus efficiently spread disease.
Culicinae mosquitoes are holometabolous, going through four distinct life stages: egg,larva,pupa, andadult. The duration of each stage is species-specific, but all Culicinae mosquitoes aremultivoltine. The egg, larval, and pupal stages areaquatic. Adults leave the water by flight to find plants or vertebrates on which to feed.Oviposition can occur in natural reservoirs ofsalt water orfresh water, or temporary pools, but oviposition sites are generally stagnant. AllPsorophora and someAedes species oviposit on soil where the eggs remain, unhatched, till flooded. Many species associate closely with humans, using accumulated ground water in developed areas for oviposition. Some species use plant cavities for oviposition. These species can, as larvae, drill into the plant for air.
Culicinae eggs are laid in groups by adult females, often numbering over a hundred. Most species lay the eggs on the surface of stagnant water. The female lays the eggs vertically and side by side, held together by a sticky substance excreted to coat the eggs, head end down, creating an egg raft that is convex below and concave above with ends that are typically upturned. Species that use this form of egg-laying typically hatch as firstinstar larvae within a few hours of laying. Oviposition on the surface of stagnant water is most common, but some species ofAedes and allPsorophora deposit their eggs in areas that will flood. Eggs are laid and embryological development occurs, but the eggs do not hatch till flooded. After flooding, the eggs will hatch within two to three days.
Culicinae larvae are adapted to almost every aquatic environment worldwide, excepting flowing streams and open areas of large water masses. Larvae have three body regions –head,thorax, andabdomen – as well as having compound eyes and antennae on their heads. The same body regions can be found in Culicinae adults, but the form of each region is very different in the larvae and adults. The larvae have fourinstars fromhatching to pupation that occur over four days to two weeks.Culicinae larvae can be distinguished from larvae of other subfamilies by the presence of the posterior siphon. The siphon is used for breathing and breaks the water surface, so the larvae can take in air. Most species hang from the surface of the water, anterior end down, so the siphon stays at the water surface. Some species ofMansonia andCoquillettidia use the siphon differently, piercing underwaterplants to takeoxygen. Larvae eat small aquatic organisms and plant material in the water using brush-style and grinding mouth parts. A few species arepredatory and have additional mouth parts for grasping. Larvae use jerks of their bodies forlocomotion, combined withpropulsion using the mouth bristles. They are sensitive to the conditions of the water in which they live, including light, temperature, and many other factors, and are also subject to predation and depend onaquatic vegetation to hide from predators.
Culicinae pupae are aquatic and do not feed, but they do require air intake. All pupae must come to the water surface for air, with the exception ofMansonia andCoquillettidia species. Pupae areexarate, allowing movement of the exposed abdomen. Thrashing of the abdomen can move the pupae quickly, sideways or downward, but as soon as movement of the abdomen stops, the pupae return to the surface of the water. The pupa naturally rises to the surface of the water due to an air pocket between the wing cases that make it lighter than water. Pupation lasts as little as one day to as much as several weeks, because somediapause can occur.
Adult mosquitoes are about equal in proportions ofmales andfemales, but males emerge from the pupal stage before females. Males stay near thebreeding ground andmate soon after the females emerge. Females only need to mate once, then store sperm to use over their lifetimes. After mating, adults leave the breeding ground and can fly great distances. Culicinae adults inhabit almost every environment, and both males and females feed onplant sugars. Females also feed on animalblood, which most species need before they can lay eggs. After a blood meal, females take two or more days to digest the blood before oviposition. After egglaying, females begin searching for anotherhost for a blood meal. Different species of mosquitoes have preferences to blood meals from specific species of hosts, but can feed on other species. Adults have three body regions, with narrowmembranes joining the segments, and are two to 15 mm in length. The first body region, the head, holds the largecompound eyes,proboscis-style mouth parts, and plumoseantennae. The antennae of males are more plumose than those of females, to catchpheromones to find a mate. The thorax is covered inscales andsetae helpful in species identification. Attached to the thorax are three pairs of long, slender legs, a pair of fore wings used for flight, and hind wings reduced to halteres for balance. The abdomen is slender, but membranous so it can swell when feeding. The abdomen has 10 segments, but only eight are visible. The last two segments are reduced and used forreproduction. Thelifespan of adult Culicinae can vary greatly based onenvironment, predation, andpest control.
Culicinae adults of both sexes feed onplant sugars, such asnectar. Feeding on blood is only practiced by females, to gain a high-protein meal for egg production. The mouth parts of females are adapted for piercing the skin of hosts, whereas the similar mouth parts of males are incapable of piercing skin. When feeding on blood, females use their large compound eyes to initially find ahost. When near a host, females can detect changes in light and odors. They can then land and use their probosces to feel for a place to bite. To feed, they pierce the skin and injectsaliva containing ananticoagulant and ananesthetic. The anesthetic reduces pain so the host does not detect the bite, and the anticoagulant prevents blood from clotting so they can continue to feed. Pathogenic organisms contained in the saliva injection by the female mosquitoes can quickly spread diseases.
The subfamily Culicinae has 3,046 species in 108 genera that are sorted into 11 tribes. The tribes and genera they contain are shown below, with the number of species in each genus noted.
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