Bee Color Vision Research Articles

A Study in Inspiration: Charles Henry Turner (1867–1923) and the Investigation of Insect Behavior

Charles Henry Turner was an African American scientist who, while eking out a living as a high school science teacher, made important advances in the study of insect learning and behavior. Contributions include the development of research methods, investigations of color vision and pattern vision in honey bees, and the first demonstration of Pavlovian conditioning in an insect. This review begins with a biography and continues with a summary of his major research accomplishments. Also included are quotations from his publications and from people who knew him. In addition, the question is raised as to why Turner did not receive an academic appointment, and similar data of racial disparity are presented on the small number of African American entomologists. It is suggested that the story of Turner can be used to increase interest in entomology, especially among African Americans.

A generalised mimicry system involving angiosperm flower colour, pollen and bumblebees’ innate colour preferences

Flower colour is a major advertisement signal of zoophilous plants for pollinators. Bees, the main pollinators, exhibit innate colour preferences, which have often been attributed to only one single floral colour, though most flowers display a pattern of two or several colours. The existing studies of floral colour patterns are mostly qualitative studies. Using a model of bee colour vision we quantitatively investigate two questions: whether or not component colours of floral colour patterns may mimic pollen signals, and whether or not bumblebees exhibit innate preferences for distinct parameters of naturally existing floral colour patterns. We analysed the spectral reflectances of 162 plant species with multicoloured flowers and inflorescences, distiniguishing between inner and outer colours of floral colour patterns irrespective of the particular structures so coloured.

Patterns of chromatic information processing in the lobula of the honeybee, Apis mellifera L.

The honeybee, Apis mellifera L., is one of the living creatures that has its colour vision proven through behavioural tests. Previous studies of honeybee colour vision has emphasized the relationship between the spectral sensitivities of photoreceptors and colour discrimination behaviour. The current understanding of the neural mechanisms of bee colour vision is, however, rather limited. The present study surveyed the patterns of chromatic information processing of visual neurons in the lobula of the honeybee, using intracellular recording stimulated by three light-emitting diodes, whose emission spectra approximately match the spectral sensitivity peaks of the honeybee. The recorded visual neurons can be divided into two groups: non-colour opponent cells and colour opponent cells. The non-colour opponent cells comprise six types of broad-band neurons and four response types of narrow-band neurons. The former might detect brightness of the environment or function as chromatic input channels, and the latter might supply specific chromatic input. Amongst the colour opponent cells, the principal neural mechanism of colour vision, eight response types were recorded. The receptive fields of these neurons were not centre surround as observed in primates. Some recorded neurons with tonic post-stimulus responses were observed, however, suggesting temporal defined spectral opponency may be part of the colour-coding mechanisms.

Colour similarity to rewarding model plants affects pollination in a food deceptive orchid, Orchis boryi

We studied the pollination of Orchis boryi at five different locations on the Greek mainland. Orchis boryi is food deceptive and obligatorily insect pollinated. Primary pollinators were Apis mellifera and Bombus spp., which foraged on rewarding plant species nearby and visited O. boryi in between. To analyse floral colour similarity among rewarding plants and O. boryi as perceived by bees, a model of bee colour vision was employed. For each food plant an index was calculated that described the probability of a bee foraging on it to subsequently choose an orchid flower. This choice probability correlated to colour distance according to the model of bee colour vision, indicating that bees chose the deceptive orchid more frequently if they foraged on more similarly coloured species. At different sites different plant species served as models. Bees foraging on food plants from which a high choice rate to the orchid was observed visited the orchid less often after approaching it than other bees, which is likely to reflect avoidance learning. In general, the pollination syndrome appears to be a generalized form of Batesian mimicry, in which similarity to rewarding plants determines reproductive success. As expected by negative density-dependent selection, individual fruit set and pollinia export rate correlated negatively with orchid density, but were unaffected by food plant density, orchid frequency, individual variation of labellum colour, labellum size, or mouth width of the flowers.

Colour similarity to rewarding model plants affects pollination in a food deceptive orchid, Orchis boryi

We studied the pollination of Orchis boryi at five different locations on the Greek mainland. E2>Orchis boryi is food deceptive and obligatorily insect pollinated. Primary pollinators were Apis mellifera andBombus sppwhich foraged on rewarding plant species nearby and visited O. boryi in between. To analyse floral colour similarity among rewarding plants and O. boryi as perceived by bees, a model of bee colour vision was employed. For each food plant an index was calculated that described the probability of a bee foraging on it to subsequently choose an orchid flower. This choice probability correlated to colour distance according to the model of bee colour vision, indicating that bees chose the deceptive orchid more frequently if they foraged on more similarly coloured species. At different sites different plant species served as models. Bees foraging on food plants from which a high choice rate to the orchid was observed visited the orchid less often after approaching it than other bees, which is likely to reflect avoidance learning. In general, the pollination syndrome appears to be a generalized form of Batesian mimicry, in which similarity to rewarding plants determines reproductive success. As expected by negative density-dependent selection, individual fruit set and pollinia export rate correlated negatively with orchid density, but were unaffected by food plant density, orchid frequency, individual variation of labellum colour, labellum size, or mouth width of the flowers.

Do "White" and "Green" Look the Same to a Bee?

The hexagon model of color vision predicts that white flowers which reflect ultraviolet light resemble green foliage to a bee's eye, whereas, according to other models of the bee color vision, UV-reflecting white is discriminable from foliage green. The hexagon model is widely used in ecologically and evolutionary oriented literature, and the predicted similarity between white and green has been recently presented as a well established fact (Waser and Chittka 1998). We show that bees detect UV-reflecting white objects presented on a green background, a finding that is in disagreement with the predictions of the hexagon model.

Atmospheric ozone concentration and the colour vision of insect pollinators

Using a theoretical model of honeybee colour vision, and considering direct and diffuse illumination conditions, it is shown that a large reduction in atmospheric ozone concentration would have a minimal effect on bee colour vision over the whole of their colour space.

BEE COLOR VISION IS OPTIMAL FOR CODING FLOWER COLOR, BUT FLOWER COLORS ARE NOT OPTIMAL FOR BEING CODED—WHY?

Model calculations are used to determine an optimal color coding system for identifying flower colors, and to see whether flower colors are well suited for being encoded. It is shown that the trichromatic color vision of bees comprises UV, blue, and green receptors whose wavelength positions are optimal for identifying flower colors. But did flower colors actually drive the evolution of bee color vision? A phylogenetic analysis reveals that UV, blue, and green receptors were probably present in the ancestors of crustaceans and insects 570 million years ago, and thus predate the evolution of flower color by at least 400 million years. In what ways did flower colors adapt to insect color vision? The variability of flower color is subject to constraint. Flowers are clustered in the bee color space (probably because of biochemical constraints), and different plant families differ strongly in their variation of color (which points to phylogenetic constraint). However, flower colors occupy areas of color space that are significantly different from those occupied by common background materials, such as green foliage. Finally, models are developed to test whether the colors of flowers of sympatric and simultaneously blooming species diverge or converge to a higher degree than expected by chance. Such effects are indeed found in some habitats.

Does Bee Color Vision Predate the Evolution of Flower Color?

Does Bee Color Vision Predate the Evolution of Flower Color?

Does bee color vision predate the evolution of flower color?

Does bee color vision predate the evolution of flower color?

Color constancy in the honeybee

A multicolored display was illuminated by 3 bands of wavelengths corresponding to the maxima of the spectral sensitivities of the 3 types of photoreceptors found in the bee retina. The intensity of each band could be varied individually. The light fluxes emitted by the colored areas of the multicolored display were determined quantitatively. Free-flying honeybees were trained with sugar solution to choose one of the colored areas. The illumination was then changed in such a way that the light fluxes formerly emitted by the training area were now measured on another area. When the trained bees were tested under those conditions, they still chose the training area. The relative positions of the colored areas were changed in order to exclude learning of position. It is concluded that color vision in bees is, in a certain range, independent of the spectral content of the illumination. Model calculations show that the behavior observed in bees is consistent with the retinex theory (Land, 1977), i.e., an algorithm using long-range interactions is required to explain color constancy.

Achromatic vision in the honeybee at low light intensities

1. Dark adapted honeybees (Apis mellifera camica) were trained in a T-maze to discriminate spectral light stimuli (λ=533, 430, and 413 nm) from dark or from an achromatic white light stimulus. 2. Bees trained to discriminate a spectral stimulus from an equally bright white light respond to the spectral stimulus as if it were the white stimulus within a certain range of intensities. This range lies between the threshold for detection of light (the achromatic threshold) and that for determination of color (the chromatic threshold); it is termed the achromatic interval. Thus the detection of spectral stimuli has two thresholds; a lower one for the absolute detection of the stimulus and a higher one for the perception of color hue. The achromatic interval for wavelengths λ=533, 430, and 413 nm is≃1.5 log10 units of light intensity. 3. Trained responses to spectral stimuli disappear at high stimulus intensities. Also, bees can not be trained to spectral lights of high intensity (>2 log10 intensity units above color vision threshold). This bright light effect is attributed to the specific response function of the lamina monopolar cells. 4. Achromatic vision is explicable in terms of known characteristics of receptor and neural organization in the bee color vision system. It is concluded that bees pool output of all receptors from a single ommatidium in a neural strategy which produces an achromatic signal. Bees use this neurally derived achromatic signal for orientation at light intensities near visual threshold.