Stevia mascotensis Soejima y Yahara

This is the final version of the article. Available from eLife Sciences Publications via the DOI in this record.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 2ºC 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.MJMH was supported by a Natural Environment Research Council studentship within the GW4 +Doctoral Training Partnership [NE/L002434/]. HMW was supported by an ERC Starting Grant (#260920). The authors would like to thank Natasha de Vere, Laura Jones and the National Botanic Garden of Wales for use of their facilities; Nick Wray and the Bristol Botanic Gardens for use of their facilities and assistance with plant species identification; Paul Chappell and Derek Carr for manufacturing the large artificial flowers; and Andy Whitcher and the Infrared Training Centre for training and advice concerning infrared cameras