Using DNA Metabarcoding to Identify the Floral Composition of Honey: A New Tool for Investigating Honey Bee Foraging Preferences

Abstract

Identifying the floral composition of honey provides a method for investigating the plants that honey bees visit. We compared melissopalynology, where pollen grains retrieved from honey are identified morphologically, with a DNA metabarcoding approach using the rbcL DNA barcode marker and 454-pyrosequencing. We compared nine honeys supplied by beekeepers in the UK. DNA metabarcoding and melissopalynology were able to detect the most abundant floral components of honey. There was 92% correspondence for the plant taxa that had an abundance of over 20%. However, the level of similarity when all taxa were compared was lower, ranging from 22–45%, and there was little correspondence between the relative abundance of taxa found using the two techniques. DNA metabarcoding provided much greater repeatability, with a 64% taxa match compared to 28% with melissopalynology. DNA metabarcoding has the advantage over melissopalynology in that it does not require a high level of taxonomic expertise, a greater sample size can be screened and it provides greater resolution for some plant families. However, it does not provide a quantitative approach and pollen present in low levels are less likely to be detected. We investigated the plants that were frequently used by honey bees by examining the results obtained from both techniques. Plants with a broad taxonomic range were detected, covering 46 families and 25 orders, but a relatively small number of plants were consistently seen across multiple honey samples. Frequently found herbaceous species were Rubus fruticosus, Filipendula ulmaria, Taraxacum officinale, Trifolium spp., Brassica spp. and the non-native, invasive, Impatiens glandulifera. Tree pollen was frequently seen belonging to Castanea sativa, Crataegus monogyna and species of Malus, Salix and Quercus. We conclude that although honey bees are considered to be supergeneralists in their foraging choices, there are certain key species or plant groups that are particularly important in the honey bees environment. The reasons for this require further investigation in order to better understand honey bee nutritional requirements. DNA metabarcoding can be easily and widely used to investigate floral visitation in honey bees and can be adapted for use with other insects. It provides a starting point for investigating how we can better provide for the insects that we rely upon for pollination.

Evaluation of Breeding Programs Susceptibility for Two Important Forage Crops Using DNA Barcoding

“…The usefulness of cox1 for determining phylogenetic relationships among tree topologies were very similar, although support values were generally lower for cox1 (Evans et al, 2007). With agreements to our findings, Hawkins et al, (2015) DNA metabarcoding and melissopalynology were able to detect the most abundant floral components of honey and plant Taxt. There was 92% correspondence for the plant taxa that had an abundance of over 20%.…”

Pollen DNA barcoding: current applications and future prospects

“…Following similar observations, suggestions that plastid DNA (ptDNA) was absent from the pollen (e.g., Willerslev et al 2003) may have discouraged early development of pollen DNA barcoding methods. Several studies have now shown proof-of-concept for amplification of ptDNA from pollen (Galimberti et al 2014;Hawkins et al 2015;Kraaijeveld et al 2015;Richardson et al 2015a), so this is no longer considered an issue.…”

“…Another strategy is to use amplicon cloning techniques (e.g., Galimberti et al 2014), but these are also labour-intensive and not comprehensive with respect to sampling depth. Recent improvements and price reductions in high-throughput sequencing (HTS) are promising in terms of addressing the issue of mixed-species identification (i.e., DNA metabarcoding), and recent studies have demonstrated the potential of these methods (Hawkins et al 2015;Keller et al 2015;Kraaijeveld et al 2015;Richardson et al 2015b;Sickel et al 2015). These recent breakthroughs could enable rapid, large-scale species identification of pollen mixtures, with the potential to transform research in a range of fields.…”

Characterisation of Nature-Based Solutions for the Built Environment

“…It is reported that green roofs flowers can provide important habitant and pollen for urban honey bees [71]. Researchers investigated antibacterial medicinal properties of urban honeys [72].…”