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Article: The diversity of floral temperature patterns, and their use by pollinators

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#1 Andy Perrin

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Posted 23 December 2017 - 02:30

Speaking of the long wave infrared...

The diversity of floral temperature patterns, and their use by pollinators

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Pollinating insects utilise various sensory cues to identify and learn rewarding flower species. One such cue is floral temperature, created by captured sunlight or plant thermogenesis. Bumblebees, honeybees and stingless bees can distinguish flowers based on differences in overall temperature between flowers. We report here that floral temperature often differs between different parts of the flower creating a temperature structure or pattern. Temperature patterns are common, with 55% of 118 plant species thermographed, showing within-flower temperature differences greater than the 2°C difference that bees are known to be able to detect. Using differential conditioning techniques, we show that bumblebees can distinguish artificial flowers differing in temperature patterns comparable to those seen in real flowers. Thus, bumblebees are able to perceive the shape of these within-flower temperature patterns. Floral temperature patterns may therefore represent a new floral cue that could assist pollinators in the recognition and learning of rewarding flowers.


#2 Cadmium

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Posted 23 December 2017 - 06:17

Materials and Methods:

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Thermographs were taken on clear and sunny days, or inside a controlled glasshouse with near-UV permeable windows, while in sunlight. Mean ambient temperature for during sampling was 14.3°C (SD 4.7). More details on the weather conditions are available in Supplementary files 2 and 3. All thermographs were taken with a FLIR E60bx thermal camera (FLIR systems, Inc., Wilsonville, USA), to a standard acceptable for I.T.C. guidelines (I.T.C, 2008; Usamentiaga et al., 2014). The thermal infrared emissivity was set at 0.98. This value is the estimate for vegetation (Rubio, 1997; López et al., 2012) and has been used for floral tissue (Rejšková et al., 2010; Dietrich and Körner, 2014). For the sake of efficiency, reflected temperature was kept at 23°C for all thermographs, due to the high emissivity of floral tissue this would have a minimal effect on temperature readings. All thermographs were viewed and measurements taken using in FLIR tools software (Flir Systems INC, 2015). Using the point measurement functions, the temperature differences between the hottest and coldest points on the flower were measured and used to calculate the temperature range across each flower.

#3 Andrea B.

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Posted 29 December 2017 - 06:16

Bees have a very sophisticated sensory system, don't they? Fascinating little critters.

(Now where can I find some of those stingless bees for the garden next summer?)
Andrea G. Blum
Often found hanging out with flowers & bees.

#4 bobfriedman

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Posted 29 December 2017 - 12:09

View PostAndrea B., on 29 December 2017 - 06:16, said:

(Now where can I find some of those stingless bees for the garden next summer?)

Male carpenter bees are unable to sting.

#5 Andrea B.

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Posted 31 December 2017 - 16:08

We had some of those around here a few years ago. I found two very well drilled round holes in the old screen porch ceiling. There were little piles of sawdust on the floor. Quite amazing that they can excavate like that. There are probably some still around, but the porch is now covered with siding, so the Carpenters must feast elsewhere.
Andrea G. Blum
Often found hanging out with flowers & bees.