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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 170 (1992), S. 267-274 
    ISSN: 1432-1351
    Keywords: Honeybee ; Monopolar cells ; Spectral coding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Monopolar cells of the first visual ganglion, the lamina, of the bee were recorded from and stained intracellularly. 2. Several different response types to pulses of spectral light were found. The most common response type hyperpolarized in a phasic-tonic fashion. The tonic hyperpolarizing response frequently decreased gradually, but in some cases increased with lasting illumination. Some cells also gave a transient response to light-OFF. In contrast, one stained and several unstained cells showed depolarizing responses. Five cells exhibited spiking responses under normal physiological conditions. 3. The V/log I-functions were steeper than those of the photoreceptors and, in some cases, had both rising and falling parts with increasing intensities. The spectral sensitivity obtained with the constant response method showed a peak in the green (510–535 nm) in most cells. A series of spectral flashes revealed an additional type with highest sensitivity in UV. Indirect evidence was found in one cell for spectral opponent processing. 4. Two morphological types of monopolar cells were stained. These correspond well to Ribi's (1976) L1 and L2 cells, with some differences in detail. The most frequently stained cell type closely resembles his L2 type. All 3 stained spiking cells were of this type.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 171 (1992), S. 171-181 
    ISSN: 1432-1351
    Keywords: Colour vision ; Flower colours ; Evolution ; Hymenoptera ; Pollination ecology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The evolutionary tuning between floral colouration and the colour vision of flower-visiting Hymenoptera is quantified by evaluating the informational transfer from the signalling flower to the perceiving pollinator. The analysis of 180 spectral reflection spectra of angiosperm blossoms reveals that sharp steps occur precisely at those wavelengths where the pollinators are most sensitive to spectral differences. Straight-forward model calculations determine the optimal set of 3 spectral photoreceptor types for discrimination of floral colour signals on the basis of perceptual difference values. The results show good agreement with the sets of photoreceptors characterized electrophysiologically in 40 species of Hymenoptera.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1351
    Keywords: Comparative colour vision ; Opponent processes ; Colour computation ; Hymenoptera ; Colour discrimination behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Behavioural tests were carried out with 9 hymenopteran insect species, which ranked certain sets of coloured stimuli according to their subjective similarity to a previously memorized stimulus. Kendall's τ coefficient is employed for the analysis of correlation between these similarity rankings and the colour distance rankings predicted by various models of neural colour computation. The models are based on the measured spectral sensitivities of photoreceptor colour types and use a variety of simple colour coding systems to derive hypothetical colour distances. The correlation between the predictions of the models and the behavioural results serves as a measure for the likelihood of existence of a colour coding system. In all species, the similarity rankings can be best explained by assuming that colour is coded on a perceptual level by two colour opponent mechanisms. Brightness differences are ignored, indicating that an intensity-coding sub-system is not used in colour discrimination by the insects investigated. The weighting factors of the colour opponent mechanisms differ between species in detail, but not in the principles involved. It is thus possible to employ a standard measure of perceptual colour distance (colour hexagon distance) to predict the capacities of colour discrimination adequately in all the tested insects.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1351
    Keywords: Photoreceptors ; Spectral sensitivity ; Colour vision ; Hymenopterans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spectral sensitivity functions S(λ) of single photoreceptor cells in 43 different hymenopteran species were measured intracellularly with the fast spectral scan method. The distribution of maximal sensitivity values (λmax) shows 3 major peaks at 340 nm, 430 nm and 535 nm and a small peak at 600 nm. Predictions about the colour vision systems of the different hymenopteran species are derived from the spectral sensitivities by application of a receptor model of colour vision and a model of two colour opponent channels. Most of the species have a trichromatic colour vision system. Although the S(λ) functions are quite similar, the predicted colour discriminability curves differ in their relative height of best discriminability in the UV-blue or bluegreen area of the spectrum, indicating that relatively small differences in the S(λ) functions may have considerable effects on colour discriminability. Four of the hymenopteran insects tested contain an additional R-receptor with maximal sensitivity around 600 nm. The R-receptor of the solitary bee Callonychium petuniae is based on a pigment (P596) with a long λmax, whereas in the sawfly Tenthredo campestris the G-receptor appears to act as filter to a pigment (P570), shifting its λmax value to a longer wavelength and narrowing its bandwidth. Evolutionary and life history constraints (e.g. phylogenetic relatedness, social or solitary life, general or specialized feeding behaviour) appear to have no effect on the S(λ) functions. The only effect is found in UV receptors, for which λmax values at longer wavelengths are found in bees flying predominantly within the forest.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Behavioral ecology and sociobiology 32 (1993), S. 17-29 
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The foraging behavior of a single bee in a patch of four electronic flower dummies (feeders) was studied with the aim of analyzing the informational components in the choice process. In different experimental combinations of reward rates, color marks, odors and distances of the feeders, the behavior of the test bee was monitored by a computer in real time by several devices installed in each feeder. The test bee optimizes by partially matching its choice behavior to the reward rates of the feeders. The matching behavior differs strongly between “stay” flights (the bee chooses the feeder just visited) and “shift” flights (the bee chooses one of the three alternative feeders). The probability of stay and shift flights depends on the reward sequence and on the time interval between successive visits. Since functions describing the rising probability of stay flights with rising amounts of sucrose solution just experienced differ for the four feeders, it is concluded that bees develop feeder-specific memories. The choice profiles of shift flights between the three alternative feeders depend on the mean reward rate of the feeder last visited. Good matching is found after visits to the low-reward feeders and poor matching following departure from the high-reward feeders. These results indicate that bees use two different kinds of memories to guide their choice behavior: a transient short-term working memory that is not feeder-specific, and a feeder-specific long-term reference memory. Model calculations were carried out to test this hypothesis. The model was based on a learning rule (the difference rule) developed by Rescorla and Wagner (1972), which was extended to the two forms of memories to predict this operant behavior. The experiments show that a foraging honeybee learns the properties of a food source (its signals and rewards) so effectively that specific expectations guide the choice behavior.
    Type of Medium: Electronic Resource
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