The role of carbon dioxide in host-finding by mosquitoes (Diptera: Culicidae): a review

From a critical review of the literature, it is concluded that the role of carbon dioxide in host-seeking by mosquitoes comprises two distinct actions. Firstly, it acts as an ‘attractant’, orientation towards the host being mediated by kinesis and optomotor anemotaxis. When tested in the absence of moving air currents, orientation to the source is not possible and only the kinetic or ‘activating’ effect is manifested. Moreover, in the absence of other host factors, sustained flight takes place only in response to intermittent pulses of carbon dioxide; this response is not elicited in uniformly permeated airstreams. Secondly, carbon dioxide has a combined action with warm moist convection currents at close range and with odour factors at a distance from the host.