Bumblebee foraging responses to variation in floral scent and color in snapdragons (Antirrhinum: Scrophulariaceae)

摘要

The roles of floral scent and colour in attracting Bombus spp. to Antirrhinum flowers, Sonnet cultivar, were investigated. Corolla colour differences covaried with differences in floral scent emissions in 2 inbred lines of snapdragon. White-floweredplants emitted methyl cinnamate, a scent compound not produced by yellow flowered plants, but lacked methyl benzoate, one of the major floral volatiles of the yellow-flowered line. Qualitative scent differences between the two lines were eliminated by applying the complementary scent compounds to filter paper wicks placed within the corollas. Laboratory analyses were performed using GC-MS to verify appropriate modification of floral scents by this method. Two randomized arrays of control and scent-augmented flowers were visited by freely-foraging bumblebees in subalpine meadows in Colorado, USA. Overall, yellow-flowered plants received more pollinator visits and had more flowers foraged per plant visit than did white-flowered plants. The addition of sweet-smelling methyl benzoate or spicy methyl cinnamate neither stimulated nor deterred bumblebee visits to either flower colour.