By Valeria Leoni, PhD student in Environmental Sciences at University of Milano – Department of Agricultural and Environmental Sciences.

Mountain wildflower honey: an endangered portrait of mountain grasslands

Mountain wildflower honey is a picture of the spontaneous flora of the mountains, an excellence from meadows and pastures of our Alps, habitats protected by the European directives. Beekeeping in environments where spring and summer are short is tougher, inside a general framework where pollinators are facing may difficulties and are in constant decline.

Furthermore, mountain areas are fragile territories subject to climate change and socio-economic change. The habitat of many Alpine floral species is decreasing due to rising temperatures and many plants have a more limited range, with the alpine biome in general reduction. Moreover, in the last decades, and still today, mountain areas are suffering a progressive depopulation. This human process has caused the abandonment of agricultural practices such as haymaking and grazing, and the expansion of forests in areas once occupied by mountain meadows, reducing the habitat for wild and domestic bees, and consequently the possibility of producing wildflower honey. Mountain wildflower honey is framed in Slow Food Presidia for this reason.

A product to study and characterize, to also understand more about honeybees

The commercial definition of honey, otherwise its botanical origin, is most times defined without carrying out formal analysis, through subjective sensory analysis or even simply considering the predominant flora that surrounds the hive.

A detailed phytochemical and melisso-palynological characterization could provide an important tool for a better honey definition: some studies have suggested possible correlations between the floral origin and profile of flavonoids, and the presence of volatile substances derived from nectar in honey aroma. The chemical composition and the consequent properties of honey depend largely on its floral source which is very dependent on the geographical origin of honey.

The knowledge of the botanical origin of honey could give important cues also for beekeeping management, since there are certain key species or plant groups that are particularly important. Although always considered generalist, apparently honeybees appear to prefer some flowers, as some Ericaceae or Rosaceae shrubs and some broad-leaved trees as sweet chestnut or Tilia genus. A valuable area of further research is to discover why these species are important and how flora composition affects bees foraging in different environments, i.e. mountain areas. Understanding the reasons why honeybees target certain plants could help to provide guidance on what constitutes a balanced honeybee diet and facilitate the process of foraging by, for example, placing apiaries in areas rich in nectar sources, considering that one of the Colony Collapse Disorder is the lack of adequate honeybees foraging resources. For example, apparently chestnut nectar could contain substances attractive for bees, as kynurenic acid, of which chestnut nectar and pollen are the most known sources, and a considerable amount of literature highlights the involvement of the neuroprotective kynurenine pathway (KP) fnal product kynurenic acid (KinA) in the regulation of the stress-related hormone dopamine in the honeybee as well as in other animal species. In this framework, plant-insect communication is a fascinating field to explore also to improve the husbandry field of beekeeping.

Let’s consider now also the pattern of the vegetation and the landscape, other than the plant species. It was seen how honeybees from the same colony forage across areas spanning up to several hundred square kilometres, and at linear distances as far as 9 km from the hive. Onlooker bees are those in charge of finding nectar sources and among them there is a difference between the bees that scout for different nectar sources or recruit to well-known floral resources, and there is an optimal ratio of scouts to recruits, for the most effective collective foraging. This balance may change based on the structure of the landscape in which the bees forage for food: theoretical models and empirical tests suggest that when resources are concentrated into a small number of highly rewarding patches, colonies perform best with few scouts and many recruits, while when resource patches are small, evenly distributed, and easy to locate, successful colonies invest more in scouting than in recruitment. This is strictly linked to climate and social changes in the mountains: mountain grasslands are no longer evenly distributed and easily localizable, as they are scattered among expanding areas of shrublands and forests and, for the above-mentioned reasons, it is more efficient for the colony to invest in more recruiters than scouters, as recruiters will identify a small number of highly rewarding patches, such as raspberry or rhododendron shrublands or linden and chestnut woods, that are highly rewarding and very different in quality.

The reverse side of the coin of the challenging activity of beekeeping in high mountain

Considering all the evaluations above, to produce mountain wildflower honey is becoming more and more difficult for beekeepers. When transhumance was widespread and regular in the Alps, bees (wild and domesticated) also benefited: the pastures were cared for and cleaned to the benefit not only of the animals, but also of the vegetation, and then the bees. Even if hives are positioned in grasslands rich in Alpine herbaceous species, nowadays beekeepers often obtain honey from the upper (as rhododendron honey) or lower botanical fascia (as sweet chestnut or linden honey) instead of mountain wildflower honey.

Yet, there is a reverse side of the coin: the poorly connected mountain territories, with few roads and little inhabitants, are also little polluted and the uncontaminated environments guarantee scarce but high-quality productions, other than being a pristine habitat also for other pollinators. Mountain wildflower honey, like many other bee products like propolis, could be interesting as well for herbal medicine and cosmetics. The production of honey in uncontaminated areas as mountain areas, can be a way of promoting this product so difficult to obtain, together with the promotion of bioactive properties of a sustainable product from marginal territories.

Reference:

Leoni, V., Giupponi, L., Pavlovic, R. et al. Multidisciplinary analysis of Italian Alpine wildflower honey reveals criticalities, diversity and value. Sci Rep 11, 19316 (2021). https://doi.org/10.1038/s41598-021-98876-y

Key words: honey, mountain grasslands, climate change, pollinators decline, honeybee behaviour, honey phytochemical composition.