Avoidance of achromatic colours by bees provides a private niche for hummingbirds

Abstract

SUMMARYThat hummingbird-pollinated plants predominantly have red flowers has been known for decades, but well-investigated research studies are still rare. Preference tests have shown that hummingbirds do not have an innate preference for red colours. In addition, hummingbirds do not depend solely upon red flowers, because white-flowered hummingbird-pollinated plants are also common and temporarily abundant. Here we show that both white and red hummingbird-pollinated flowers differ from beepollinated flowers in their reflection properties for ultraviolet (UV) light. Hummingbird-pollinated red flowers are on average less UV reflective, and white hummingbird-pollinated flowers are more UV reflective than the same coloured bee-pollinated ones. In preference tests with artificial flowers, neotropical orchid bees prefer red UV-reflecting artificial flowers and white UVnonreflecting flowers over red and white flowers with the opposite UV properties. By contrast, hummingbirds showed no preference for any colour in the same tests. Plotting floral colours and test stimuli into the honeybees' perceptual colour space suggests that the less attractive colours are achromatic for bees and therefore more difficult to detect against the background. This underlying colour preference in bees might provide hummingbirds with a private niche that is not attractive to bees. Supplementary material available online at

Flowering phenology of Mouriri guianensis (Melastomataceae) and its interaction with the crepuscular bee Megalopta amoena (Halictidae) in the restinga of Lençóis Maranhenses National Park, Brazil

“…Red flowers pollinated by hummingbirds, for example, represent a color niche that only hummingbirds can identify, as these flowers are inconspicuous to bees (Lunau et al 2011). This study appears to furnish an example of an interaction mediated by this principle, suggesting that the blooming of the plant at twilight is a strategy to escape from undesirable visitors.…”

“…In contrast, an interesting idea about the resource partitioning and resource sharing is "sensory exclusion", where interactions occur in sensory windows to which less efficient members may not have access (Lunau et al 2011;Brito et al 2014). Red flowers pollinated by hummingbirds, for example, represent a color niche that only hummingbirds can identify, as these flowers are inconspicuous to bees (Lunau et al 2011).…”

Plantas, polinizadores e algumas articulações da biologia da polinização com a teoria ecológica

“…O sistema sensorial dos polinizadores possuem propriedades inatas que podem afetar a percepção e a preferência por estímulos (Schaefer & Ruxton 2009;Lunau et al 2011). Desta forma, as plantas podem explorar o sistema sensorial dos polinizadores ao emitir um sinal inatamente preferido por ele e esse mecanismo pode ser muito mais comum que o mimetismo.…”

Getting to the start line: how bumblebees and honeybees are visually guided towards their first floral contact

“…Neurophysiological experiments show that bumblebees and honeybees have peak spectral sensitivities at approximately 350, 450 and 550 nm, which correspond to ultra-violet (UV), blue and green regions of the spectrum (Peitsch et al, 1992;Skorupski et al, 2007). There are no receptors with peak sensitivity near red, which likely accounts for poor learning of red (Chittka, 1997;Lunau et al, 2011), even in species (e.g. Bombus dahlbomii Guérin-Méneville, 1835) that are known to visit red flowers (Martínez-Harms et al, .…”