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- Araújo, Priscila, et al.
(författare)
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Body size and the architecture of the visual system in crepuscular and diurnal bees
- 2023
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 138:3, s. 328-340
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Tidskriftsartikel (refereegranskat)abstract
- Crepuscular bees have larger compound eyes, ommatidia and ocelli than diurnal bees. These visual adaptations allow these bees to forage during twilight. While the sizes of visual organs are positively correlated with body size in diurnal bees, this relationship is as yet unclear in crepuscular bees. Here we measured the sizes of the ocellus; compound eyes; ommatidial density; and dorsal, frontal and ventral facets of 11 phylogenetically related bee species with different temporal patterns. We tested whether and how each of these visual attributes is correlated with body size and/or temporal pattern. Except for ommatidial density and size of the frontal ommatidia, which are similar in crepuscular bees of different sizes, we found that all other visual variables in diurnal and crepuscular bees are correlated with both body size and temporal pattern. The lower variability in ommatidial density among crepuscular bees suggests that their eyes operate on the threshold between light sensitivity and visual acuity. Furthermore, similar frontal ommatidial sizes in bees of different sizes indicate that this eye region is under higher evolutionary pressure in small than in large crepuscular bees to ensure light sensitivity. Finally, those crepuscular bees from different families convergently share the same visual characteristics.
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| 2. |
- Araujo, Priscila, et al.
(författare)
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The role of visual and olfactory floral cues in twilight foraging by Ptiloglossa and Xylocopa bees
- 2024
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Ingår i: Behavioral Ecology and Sociobiology. - 0340-5443 .- 1432-0762. ; 78:2
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Tidskriftsartikel (refereegranskat)abstract
- Bees of Ptiloglossa and Xylocopa explore the chiropterophilous flowers of Pseudobombax longiflorum at twilight, but how the bees find the flowers in low light is unclear. In field experiments, we investigated if visual and olfactory floral cues are used by these bees to find P. longiflorum flowers, and which behaviors are triggered by these cues. While the crepuscular Ptiloglossa bees were more attracted to flowers with a combination of visual and olfactory cues than to isolated cues, the diurnal Xylocopa bees were equally attracted to the combination of visual and olfactory cues and to flowers with visual cues alone. Ptiloglossa bees visit the flowers under lower light intensity than Xylocopa bees. This indicates that the synergy between visual-olfactory cues facilitates flower detection in crepuscular bees. However, in higher light intensities, the large size of flowers with their broad spectrum reflectance may be enough to produce a reliable visual signal for the Xylocopa bees. Olfactory stimuli alone trigger only floral approaches in bees, while visual ones frequently trigger approaches followed by landings on flowers. This suggests that olfactory cues guide the bees to the flowers in twilight, but the presence of a visual cue is necessary to trigger landings and collection of floral resources.
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