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The appetitive search

After emergence, or after taking a blood meal, an adult female mosquito

goes through a latent period when it will not blood-feed. InAnopheles

gambiae, this period of inhibition of response to human odour lasts for at

least 40 h after a blood meal (Takkenet al., 2001). Similar inhibition of

activity is seen in other mosquito species (see references in Daviset al.,

1987), and inA. aegyptiinhibition lasts until after oviposition (Klowden,

1987).

However, as the female matures or the blood meal is digested and eggs

mature, the imperative for the female to acquire a blood meal becomes

increasingly urgent. Thus the female undertakes periodic, non-orientated

flight activity to increase her chances of encountering host-derived cues

and obtaining a blood meal (Lehane, 1991). This behavioural pattern has

been recognized in other Diptera apart from mosquitoes, e.g. ranging

behaviour in tsetse-flies (Vale, 1980). The questing behaviour exhibited by

ixodid ticks is believed to perform a similar function (Waladde and Rice,

1982). Undoubtedly this behaviour occurs in many groups of blood-feed-

ing arthropods.

No work has been undertaken that we are aware of to specifically

address the effect of parasitic infection on appetitive search behaviour.

264 J.G.C. Hamilton and H. Hurd

Endogenous

factors

Vector behaviour Exogenous

factors

Insect age

Host

preference

Nutritional

state

Reproductive

state

Biting habit

Nocturnal

Crepuscular

Diurnal

1. Appetitive search
   2. Activation and
   orientation


2. Attraction


3. Landing and
   probing

Temperature

Humidity

Wind speed

Light intensity

Host availability

Host factors

CO 2

Host odours

(olfactory and

gustatory)

Visual cues

Temperature

Fig. 13.1. Factors affecting the blood-meal-seeking process.