LARVAL AND ADULT NUTRITION EFFECTS ON BLOOD NECTAR CHOICE OF CULEX NIGRIPALPUS MOSQUITOS/

The impact of nutritional variables on the development of host-seeking and biting behaviours after emergence by female Culex nigripalpus mos quitoes were studied using air-flow olfactometer and close-range bitin g assays, respectively. Unfed females failed to develop resting stage ovarian follicles. When offered a bird host in the absence of competin g stimuli, sugar-fed mosquitoes were significantly more responsive in both host-seeking and biting than unfed controls. In a choice olfactom eter assay using nectar odours (honey scented with artificial apple-bl ossom oil) versus host odours (a bird), unfed females preferred honey over bird odours except when honey odour was weak. After sucrose feedi ng, females switched from honey to bird preference. This change in beh aviour was accompanied by significant accumulation of lipid and by fol licular growth to the resting stage. Elevation of host responsiveness after sugar feeding was reversible; starvation ultimately resulted in females preferring honey over bird odours. When the larval diet was re stricted by crowding, the wing-length and total lipid of resultant adu lt females were reduced. Although differences were subtle, unfed bird- responding females tended to have longer wings and more lipid than the ir honey-responding counterparts.