The location of floral nectar sources by mosquitoes: an advanced bioassay for volatile plant odours and initial studies withAedes aegypti(L.) (Diptera: Culicidae)

The development and testing of a bioassay system to evaluate the potency of floral odours as mediators of long-range floral nectar source location by mosquitoes are described. The bioassay is quantitative and behaviourally discriminating, upwind flying and landing acting as indices of behavioural activity over the 24-h light:dark cycle. In initial tests, the responses ofAedes aegypti(L.) to the flowers and floral odours of ox-eye daisy (Leucanthemum vulgare) were investigated.A. aegyptiexhibited a biphasic diel cycle of nectar-feeding behaviour and landed on modified flowers that retained either their disc or ray florets. Most significantly, the mosquitoes responded in a similar way to the odour ofL. vulgarein the absence of visual stimuli or nutritional cues. They did not respond to solvent extracts of ox-eye daisy flowers.