Flower colour and visitation rates of Costus arabicus support the 'bee avoidance' hypothesis for red-reflecting hummingbird-pollinated flowers

摘要

1. Floral colour mediates plant-pollinator interactions by often signalling floral resources. In this sense, hummingbird-pollinated flowers are frequently red-coloured, and there are two tentative hypotheses to explain this pattern: 1. hummingbirds are attracted to red due its easier detection and 2. bees are sensorially excluded from red flowers. The second hypothesis is based on bees' red colour blindness, which lead them to be less frequent and less important than hummingbirds as pollinators of red-reflecting flowers.