Potato leafbopper (Homoptera: Cicadellidae) varietal preferences in edible beans in relation to visual and olfactory cues

Migratory adult potato leafhoppers, Empoasca fabae (Harris), have shown a preference for particular cultivars of edible beans, Phaseolus vulgaris L. Laboratory experiments were conducted to determine the role of visual and olfactory cues in these preferences. No preference for any particular cultivar of edible bean was detected in Y-tube olfactometer binary comparison tests: when selecting leaves on the basis of olfactory stimuli. Adult potato leafhoppers chose 'Berna Dutch brown' as frequently as 'Stingray white' bean and 'EMP 419'. When adult potato leafhoppers selected leaflets of uniform shape and size from an aerial position in a Plexiglas chamber, 'Berna Dutch brown' was significantly preferred (54%) over 'Stingray white bean' (24%) and 'EMP 419' (22%). An external integrating sphere attached to a portable spectroradiometer was used to determine the wavelength reflectance of 'Berna Dutch brown','Stingray white', and 'EMP 419' bean leaflets. 'Berna Dutch brown' bean leaflets had higher percent reflectance readings in the green region of the spectrum and lower percent reflectance readings in the blue and yellow regions of the spectrum compared with 'Stingray white' and 'EMP 419'. Although host-finding behavior may involve an interaction between visual and olfactory stimuli, the results of this study indicate that leaf color significantly influences host preference, whereas host odor does not.