Overview

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; and

(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 odor 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 odors 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.

Feeding Habits

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<//li>
• 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.