| 1. |
- 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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| 3. |
- Cordeiro, Guaraci D., et al.
(författare)
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Nocturnal bees as crop pollinators
- 2021
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Ingår i: agronomy. - : MDPI AG. - 2073-4395. ; 11:5
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Tidskriftsartikel (refereegranskat)abstract
- Bees are typically diurnal but around 1% of described species have nocturnal activity. Nocturnal bees are still poorly studied due to bias towards studying diurnal insects. However, knowledge concerning their biology and role as crop pollinators has increased. We review the literature on nocturnal bees’ traits and their host plants, and assess the crop pollination effectiveness of this neglected group. Nocturnal bees have visual adaptations to cope with low light intensities, and floral scents are a key sensory cue used to find their host flowers. Nocturnal bees generally show high flower constancy, the ability to vibrate flowers, and high transfer rates of pollen grains to stigmas. The flowers visited by nocturnal bees range from small radial and zygomorphic flowers to large brush blossoms; moreover, they visit plants with different flowering strategies. Nocturnal bees are effective pollinators of regional fruit crops in Brazil, such as cambuci (Campomanesia phaea), guaraná (Paullinia cupana), cajá (Spondias mombin), and in North America of cultivated pumpkins (Cucurbita species). However, they most likely are pollinators of several other crops. Strategies to host high numbers of nocturnal bees around cropping areas should be taken, such as preserving adjacent native forests, restricting soil management, providing food resources beyond crop flowers, and avoiding light pollution.
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| 4. |
- Liporoni, Rodolfo, et al.
(författare)
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Light intensity regulates flower visitation in Neotropical nocturnal bees
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- The foraging activity of diurnal bees often relies on flower availability, light intensity and temperature. We do not know how nocturnal bees, which fly at night and twilight, cope with these factors, especially as light levels vary considerably from night to day and from night to night due to moon phase and cloud cover. Given that bee apposition compound eyes function at their limits in dim light, we expect a strong dependence of foraging activity on light intensity in nocturnal bees. Besides being limited by minimum light levels to forage, nocturnal bees should also avoid foraging at brighter intensities, which bring increased competition with other bees. We investigated how five factors (light intensity, flower availability, temperature, humidity, and wind) affect flower visitation by Neotropical nocturnal bees in cambuci (Campomanesia phaea, Myrtaceae). We counted visits per minute over 30 nights in 33 cambuci trees. Light intensity was the main variable explaining flower visitation of nocturnal bees, which peaked at intermediate light levels occurring 25 min before sunrise. The minimum light intensity threshold to visit flowers was 0.00024 cd/m2. Our results highlight the dependence of these nocturnal insects on adequate light levels to explore resources.
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