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 Major Groups | Insecta (insects) | Diptera (true flies) | Culicidae
 

Culicidae

Major Group: Insecta
Order:
Diptera
Family:
Culicidae (now excluding Dixidae, Chaoboridae, Corethrellidae)

Descriptive Features:

  • antenna non-prehensile
  • mouth brushes present
  • 3 thoracic segments fused and enlarged, broader than abdominal segments
  • prolegs not present on any segment
  • head capsule complete, not retractile into thorax
  • mandibles usually with several teeth
  • abdomen 9-segmented
  • Total length:
  • Taxonomic Checklist: Subfamilies
    Anophelinae
    Culicinae
    Note: The genus Toxorhynchites was formerly in its own subfamily, Toxorhynchitinae, but is now within Culicinae. Toxorhynchites larvae are resticted to plant-held water.

    Distribution: Australia wide

    Sensitivity Rating: SIGNAL grade 1

    Functional Feeding Group: filtering collectors, scrapers, predators

    Ecology: Adults are commonly known as ‘mosquitoes’ but not all species of Culicidae are pests to humans.
    Instream habitat: The larval habitat is chosen by the female when she deposits her eggs. She is able to discern physical and chemical properties of different water bodies. Larvae are cosmopolitan, occurring in groundwater lakes, swamps, streams, temporary and semi-permanent ground pools, rain filled depressions, animal wallows, plant-held water, rock pools, flooded animal and crayfish burrows, irrigation drains, dams, wheel ruts, as well as various small container habitats. They can tolerate organically polluted water such as septic tanks, drains, sludge pits, ground water at garbage dumps, as well as brackish water such as estuarine marshes and swamps, tidal reaches of river margins and irrigation run-off in inland areas with saline soil. Within these habitats, the larvae are found in vegetated margins, floating vegetation, isolated quiet reaches and backwaters.
    Feeding ecology:Most mosquito larvae feed on small algae and detritus but by differing methods. Some species (e.g. of Anopheles, Culex, Culiseta, Mansonia) are filter feeders of suspended organic matter using elaborate brushes on either side of the labrum with which they create a current to pull in food from the water column (e.g. Culex) or water surface (e.g. Anopheles) whereas other species (e.g. of Tripteroides, Aedes in part) scrape material from submerged surfaces. Other species of Aedes and all species of Toxorhynchites are predators usually feeding on other smaller mosquito larvae. Females feed on the blood of mammals, including humans, to obtain protein to develop batches of eggs. They also feed on plant nectar or honeydew (the sweet liquid excreted by aphids and some other plant feeding insects) to gain energy for flight. Males of most species do not take blood-meals instead they take sugar-meals.
    Habit: Mosquito larvae, except for Mansonia, breathe atmospheric oxygen through an abdominal siphon or spiracles; when not feeding most of them hang suspended from the surface film. Larvae and pupae are active swimmers and dive rapidly when disturbed. Mosquito pupae breathe through a pair of breathing horns attached to their first thoracic segment, so the orientation of the animal in the water alters from upside down, as a larva, to upright, as a pupa, with the back of the pupae towards the water surface. This allows the adult to break through the pupal skin then through the water surface as it emerges. Larvae and pupae of Mansonia are thought to remain attached to aquatic vegetation to obtain oxygen and avoid predators.
    Life history: The timing of the mosquito life cycle is very temperature dependant (low temperatures will delay development), but also species dependant. Some species are univoltine, while others will have several generations during a season of favourable climatic conditions. In south-eastern Australia, some Culicidae species remain reproductively active throughout the entire year. Immediately following emergence, the adult female generally seeks out a sugar-meal to replenish her energy reserves. Later she seeks a blood-meal then searches for a secluded refuge where she can rest undisturbed and develop a batch of eggs. Eggs take two to four to mature but low temperatures may extend development period up to ten days or more. When the eggs are mature the females will fly to a suitable place for larval development where mating often occurs at dusk and on the wing. Females only mate once, the sperm pack introduced by the male during the mating act will fertilise all the subsequent egg batches she will produce. Females lay their eggs as single units or in a mass, on the water surface or attached to submerged aquatic plants or on a moist substratum above the water level where they will be subsequently flooded. Eggs on or in the water are completely dependant on the presence of water for survival and usually hatch in about 2 days. Those eggs above the water are able to withstand desiccation and can survive for long periods until the water level rises, at which time they begin to hatch, often in batches. During favourable summer conditions larval development may be complete in four to ten days, but some species have, or adverse conditions may contribute to, a larval stage of more than 3 weeks. There are four larval instars, each, increasing in size, followed by a non-feeding but mobile pupal stage. The duration of the pupal stage is generally two to nine days. Emergence of the adults occurs through a dorsal longitudinal split in the cephalothorax. Once free of the pupal skin, the adult rests for about an hour either in the water surface or on riparian vegetation, during which time the wings unfold and harden. The time period from egg to adult varies with environmental variables, particularly temperature, but two to three weeks under optimum conditions is enough for most species to reach the adult stage. The males of a species may develop marginally quicker than the females and males are usually the first to emerge from the larval habitat but they have a short lifespan of one week or less. Females usually live much longer, up to three or more months, however the usual life span is two to four weeks. The longevity of mosquitoes is dependant on predators with less than 10% of mosquitoes surviving more than 10 days as adults.
     
     
    Information Sources: Russell 1993, Colless & McAlpine 1991, Williams 1980, Hawking & Smith 1997, Gooderham & Tsyrlin 2002, Bugledich 1997, 1999, Williams & Feltmate 1992, Merritt & Cummins 1996, Cuda & Hornby 1995
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