Floral Diversity of Pollen Collected by Honey Bees (Apis mellifera L.) – Validation of the Chromatic Assessment Method

Abstract

A b s t r a c t Pollen collected from flowers by forager bees is the only natural protein source for the hive. This nutritional compound is fundamental for the nurse bee and brood development, and for the queen activity. Pollen has a strong influence on colony health. It is also known that the pollen quality, in terms of the amino acid profile and total protein content, varies significantly according to the floral origin. For this reason, the palynological diversity assessed in corbicular pollen is a good measure of the quality of the environment the bees live in, in terms of available food. An international research initiative "C.S.I. Pollen" aims to elaborate a pollen diversity map for all of Europe, carried out by beekeepers. Chromatic assessment of pellet colours will be used as a method. In our study, we wanted to validate this idea, through the comparison between the two methods: chromatic assessment of the diversity of pollen pellet colours and palynological assessment of the real pollen type diversity. In other words, we wanted to verify whether the pellet-colour profile reflects the palynological one. We found a significant correlation between results obtained from the two methods but some improvements are also proposed in order to increase the determination coefficient and to reduce the differences given by the two answers.

A citizen science supported study on seasonal diversity and monoflorality of pollen collected by honey bees in Austria

“…These findings are again comparable to other studies on pollen diversity 21,26,32 . Compared to the study in Thessaloniki, Greece 15 , we identified more pollen types, which can be attributed to the larger number of rare pollen types in Austria (Fig.…”

“…In some countries citizen scientists were also equipped with sample bags and instructions on how to prepare and conserve samples for later palynological analysis in a laboratory. Therefore, comparable results to this Austrian study are available from seven locations in Liguria, Italy 32,34 .…”

“…Nevertheless, within this study we demonstrate that honey bees in Austria forage on a broader pollen source spectrum compared to many studies conducted in other countries 15,21,25,27,28,32,38,46,55–59 . To cite only a few examples, a comparative sampling and analysis in Northwestern Italy found a total of 90 different ‘palynological types’ 32 . At a single site, and over 9 sampling dates, the highest number of different pollen sources in our study was 105.…”

“…The international C.S.I. Pollen study (citizen scientist investigation on pollen diversity forage available to honey bees), coordinated by the honey bee research association COLOSS, of which this study is the Austrian branch, was comprised of two levels: in many European countries citizen scientists were asked to collect pollen every three weeks and to identify the number of different colours in the pollen sample to roughly estimate pollen diversity 32,33 . That study involved the recruitment and training of citizen scientists in regard of installing pollen traps, sampling, processing the pollen samples and cleaning the equipment to prevent sample contamination.…”

The Colours of Pollen Available to Honey Bees through the Year

“…Pollen-load colours can be used to record the diversity of plants from which bees forage (Kirk, 2006), but caution is needed because one plant species can produce more than one pollen colour and very different species can have pollen loads with identical colours (Hodges, 1952;Hidalgo & Bootello, 1990;Kirk, 2006). However, measurements have shown that there is a good correlation between colour analysis and palynological analysis (Conti et al, 2016).…”