Flower chafers and their potential for non-forest biotope conservation
Flower chafers (Cetoniinae) are charismatic beetles well-known, even to the wider public, as metallic greenish-gold visitors of flowers or as exotic pets. Of course, not every beetle with a metallic sheen is a flower chafer, and not every flower chafer resembles a colourful jewel. Nevertheless, flower chafers can easily be recognised by an educated layperson. Therefore, well-recognisable endangered species can be utilised in protecting habitats teeming with biodiversity. Many such species are saproxylic, i.e. living in dead wood. If a person finds a saproxylic flower chafer, such as Osmoderma barnabita, they can safely assume they have found an old solitary tree deserving special attention and protection as a safe haven for an assemblage of organisms. They will be less conspicuous than flower chafers, but linked to the same solitary trees that are rare and sporadically scattered in the landscape. By protecting habitats suitable for Osmoderma, we protect these entire assemblages.
Certain species, the presence of which allows us to propose the conservation of whole localities, are termed flagship or umbrella species. They are easily identifiable by laypeople who, if instructed what to look for, could help map the individual localities of these flagship species. Indeed, the public, especially amateur entomologists, have contributed significantly to the rediscovery of populations of flower chafers linked to non-forest biotopes, such as the sandy beach ‘Velika plaža’ in Montenegro or the ‘Macedonian steppe’ in North Macedonia. Dominik Vondráček, David Král, and Petr Šípek from the Department of Zoology, Faculty of Science, have investigated these soil-dwelling flower chafers.
They focused on two species of the genus Oxythyrea, namely O. dulcis inhabiting Mediterranean coastal sand dunes, and O. albopicta, a steppe specialist that is currently known in only one European locality: the arid Macedonian steppe in North Macedonia. The former biotope is considered to be one of the most endangered in Europe; as over 70% of coastal sand dunes have disappeared over the course of the last century, mainly due to human pressure (construction of infrastructure for tourists, removal of coastal vegetation, etc.). One such coastal biotope that is shrinking year by year due to tourism is the Velika plaža beach in Montenegro. Although the Macedonian steppe where O. albopicta occurs is not under similarly intense human pressure, it is one-of-a-kind locality characterised by unique flora and conditions typical for Anatolia rather than the Balkans.
Both Oxythyrea dulcis and O. albopicta are specialists linked to specific non-forest habitats occurring in the landscape as figurative islands of biodiversity. This closely resembles the situation encountered with Osmoderma regarding solitary trees. However, unlike saproxylic species, the potential of non-forest specialists for protecting such biotopes has yet to be assessed. This is further complicated by the fact we seem to know very little about such species, even those that are well-known; for example, the aforementioned Osmoderma barnabita used to be known as Osmoderma eremita until recent genetic analyses revealed that O. eremita is a complex of four cryptic species, with O. barnabita the only one occurring in Czechia.
Thus, the authors examined the genetic structure of Oxythyrea dulcis and O. albopicta in order to compare the relict populations in Montenegro and North Macedonia with conspecific populations, as well as populations of congeners that are widespread in Europe (e.g. Oxythyrea funesta). This enabled them to assess the potential of O. dulcis and O. albopicta for the conservation of fragmented non-forest biotopes. In accordance with the assumption that the populations of species from fragmented habitats will be more isolated, the genetic analyses revealed much more pronounced population structure with presumed lower gene flow in specialist species.
A surprising revelation was that O. dulcis from coastal sand dunes comprises multiple genetically isolated lineages. This was unexpected, given that sandy non-forest biotopes are oftentimes unstable and ephemeral. Species associated with O. dulcis can usually disperse over long distances, and thus exhibit genetic population structuring only at larger geographic scales. Even greater genetic diversification was observed in O. albopicta. The genetic differences within both species are more pronounced than interspecific genetic differences in other flower chafers. This suggests the need for taxonomic revision of these species; the authors are currently working on elevating the Adriatic-Ionian lineage of O. dulcis to species status.
Both currently recognised species of specialised Oxythyrea contain relict populations with cryptic diversity, and as such merit further conservation efforts directed at both themselves and, more importantly, the protection of their specific non-forest habitats. Moreover, the authors list other flower chafers that could potentially be used as flagship species for non-forest biotopes, such as Paleira femorata from Iberian Peninsula (sand dunes) or Protaetia (Philhelena) ungarica (a steppe specialist in the northern part of its distribution range). Given that non-forest specialists may react negatively to management changes (afforestation, lack of grazing, etc.) affecting their habitat, such species can act as indicators of ecosystem health. Just as Osmoderma and other saproxylic beetles serve as flagship species for the conservation of old solitary trees, so other flower chafers may serve to protect non-forest biotopes.
Vondráček, D., Král, D., & Šípek, P. (2022). Cryptic diversity of Oxythyrea flower chafers and its implication for conservation of non‐forest biotopes in the Balkans. Insect Conservation and Diversity. 16(1), 133–146.