by Symington & Rockx
Photo
by Alexander Grey on Unsplash
(http://bit.ly/4lx6mVj)
To analyse the energetic content of the nectar reward which plants offer to pollinators, we must know the amount of sugar in that nectar. This depends on the volume, density and sugar concentration of the nectar in question. The relationship between sugar concentration and nectar density is not linear – it follows a curve, which can be modelled with an equation (density = 0.0037291C + 0.0000178C2 + 0.9988603, where C is the concentration).
We noticed that two digits within that equation were switched in a report from 2001 (0.0037921C, instead of 0.0037291C). Other studies then used this incorrect equation to calculate nectar density and report nectar sugar mass. We wanted to see which version was closer to the measured density of sugar solutions of different concentrations, and using the incorrect version caused a significant difference to the conclusions of any studies.
We found that using the incorrect equation gives results which are only marginally different to those given by using the correct equation, and that the errors introduced are less than errors caused by variation in temperature when sampling, or by measurement error of nectar volume or concentration. We also found that some studies report the use of other equations for calculating nectar sugar mass, sometimes with typographical errors, but the errors introduced do not affect the conclusions of these studies. (We should be clear that we are not calling the methods of any study into question, only the reporting of nectar sugar mass.)
So why report on this, if there is little difference between the equations used? When we noticed this discrepancy, we were unsure whether this error would cause a material difference over 20 years’ reporting, and wanted to be clear on this ourselves. We are pleased that our work has given us confidence in the results of other studies, and wanted to share that confidence with other researchers. We also feel it is beneficial to be clear on which equation should be used to calculate nectar sugar mass.
