Blood feeding in mosquitoes follows a species-specific circadian rhythm, which is mainly nocturnal.
Generally three main categories can be distinguished:
- (1) nocturnal, if feeding occurs at night – many, probably most species belong to this group, e.g. some Aedes species and Mansonia africana;
- (2) diurnal, if feeding occurs largely during daylight hours, e.g. Aedes apicoargenteus and Aedes longipalpis; and
- (3) crepuscular, if feeding occurs largely during twilight hours, at dusk or at dawn, e.g. Aedes africanus and Anopheles gambiae (Goma, 1966).
Host Seeking Behaviour
The mosquito's selection of the host seems to be determined by four main factors:
- (1) availability of the host;
- (2) climatic conditions and resting habits of the mosquitoes concerned;
- (3) emanations of the host;
- (4) visual stimuli (Goma, 1966).
Two main determinant complexes influence mosquito host location: endogenous determinants such as genetic make-up, age, mating condition, gonotrophic status, nutritional status and circadian rhythm of the female mosquito; and exogenous determinants, defined by the host and the environment. The mosquito host-finding can be divided into successive phases: activation, oriented flight to the host, alighting on the host, probing, ingestion, withdrawal, and take-off (Mehlhorn, 2001).
Oriented flight is regulated by anemotaxis. Movements of the host are registered by optomotor responses and emanations are noticed. Depending on the species, exhaled air, with carbon dioxide as the most stimulating component, or particular skin emanations are registered. Long distance (up to 70 m) is achieved by odour cues, CO2 attracts over distances of about 20 m, and heat and humidity additionally cover a distance of 1-2 m. Besides CO2, many other chemicals have proven attractive potential.
Alighting involves, additionally to CO2 and odours, visual stimuli and warm, moist convection currents.
Probing is stimulated by thermal gradients, humidity, CO2, the mechanical quality of the surface, and special chemicals.
Ingestion of blood is evoked by platelets and various adenine nucleotides in combination with osmotic conditions.
Termination of feeding is controlled by segmental stretch receptors in the abdomen.
Diverse feeding habits are distinguished in haematophageous insects:
- anthropophagic/anthropophilic: mosquitoes biting (preferably) humans
- zoophagic/zoophilic: mosquitoes biting lifestock and other animals
- endophagic: mosquitoes biting mainly inside houses
- endophilic: mosquitoes resting indoors after blood-feeding while the meal is digested and the eggs mature
- exophagic: mosquitoes biting mainly out of doors
- exophilic: mosquitoes resting outdoors after blood-feeding while the meal is digested and the eggs mature
Many species exhibit a mix of these behavioural patterns, often not being exclusively one of them.
Mosquitoes obtain their blood meals from a very wide variety of hosts. These include warm-blooded animals as birds, cattle, pigs, numerous wild animals, and humans; and cold-blooded animals such as frogs, lizards, snakes, insect nymphs and pupae. The choice of host varies greatly with species of mosquito and the availability. Many species have a marked predilection for one type of host which they select if reasonable available, taking other hosts only in the absence of their preferred food (Macdonald, 1957). Other mosquitoes have no particular preferences and will feed readily on a wide range of hosts.
- Goma LKH: The mosquito. 1966, Hutchinson Tropical Monographs, Hutchinson & Co. (Publishers) LTD, London
- Macdonald G: The epidemiology and control of malaria. 1957, Oxford University Press, London
- Mehlhorn H: Mosquitoes. In: Mehlhorn H (ed.): Encyclopedic reference of parasitology. Biology, structure, function. 2nd edn., 2001, Springer Verlag, Berlin, pp. 378-84