Coleoptera-Scarabaeidae

Osmoderma barnabita Motschulsky, 1845 is a threatened scarab beetle living in the hollows
of old deciduous trees. Beetles of the genus Osmoderma are known for their fruity odour,
which is released by males. Pheromone-baited traps were used for the first time for the
study of distribution of O. barnabita in Latvia and new data about the species distribution
were obtained. The capture-mark-recapture method was used to estimate dispersal ability
of O. barnabita. Our results suggest that maximum dispersal distance (2090 m) observed
in this study is the farthermost record from wild Osmoderma populations till now.
Key words: Osmoderma barnabita, pheromone-baited traps, dispersal distance, Latvia

Urban parks can harbour small populations of saproxylic insects of high conservation concern, such as Osmoderma eremita and other rare beetles. These areas often host old trees which have become very uncommon in rural areas where they are threatened by commercial forestry management procedures based on frequent tree cutting. Nevertheless, old trees of urban parks may represent a hazard for public safety and are sometimes cut by management authorities. The aim of this work was to assess the loss of reproductive sites for saproxylic beetles of the Scarabaeidae, Lucanidae and Cerambycidae, when felling plans are adopted according to a Visual Tree Assessment Procedure (VTA), in a Mediterranean urban park. On July–August 2004, 1,247 holm oaks were surveyed within the border of an urban park of Rome (Villa Borghese). The occurrence of saproxylic beetles (i.e. the presence of frass, living insects or their remains) was verified in 66 old holm oaks, 41% of which were doomed to cutting by VTA. Eleven of these trees (41% of the trees doomed to be cut) held fragments of adults and sometimes living larvae of Osmoderma eremita, and four of them (36%) were included in the felling plan. The presence of Osmoderma eremita in tree holes was more frequent in deep cavities. The presence of frass in the cavities was positively associated with tree height and a high degree of damage at the root collar and negatively with the presence of hole-nesting birds.

A molecular analysis was carried out on the European hermit beetles (the Osmoderma eremita species complex) to explore their genetic diversification and the robustness of previous morphologically based taxonomic arrangements. Complete sequences of mtDNA cytochrome C oxidase I gene were obtained from 26 individuals. Mean levels of interspecific sequence divergence ranged from 0.044 to 0.186. The results indicate a clear-cut distinction between two clades. The first one includes the W-European O. eremitaScopoli 1763; and the two Italian endemic taxa Osmoderma italicumSparacio, 2000 and Osmoderma cristinaeSparacio, 1994; from southern peninsular Italy and Sicily, respectively. The second one includes the widespread E-European Osmoderma barnabita; and the southern Balcanic Osmoderma lassalleiBaraud and Tauzin, 1991 from Greece and European Turkey. Within the two clades, molecular and morphological data well support a specific rank for O. lassallei and O. barnabita on one side, and for O. eremita and O. cristinae on the other side, while the taxonomic position of O. italicum, more closely related to O. eremita, is still uncertain. Current geographical distribution, interspecific genetic diversification, and very low levels of intraspecific genetic divergence in western European populations of O. eremita sensu stricto are hypothesized to be the result of multiple speciation events (mainly occurred in refugial forest areas of the Italian and Balkan peninsulas and Sicily before and during the Pleistocene glacial peaks), followed by fast post-glacial northward and westward expansion of some species.

Life cycle of the orphnine scarab beetles genus Chaetonyx was recorded for the first time based on the multiyear observations on the populations of its type species, Ch. robustus Schaum, 1862, in riverside habitats at Zemen Gorge region, South-Western Bulgaria. Our observations showed that this geobiont species is common in alluvial soils near Struma River, where it forms large colonies. At the Zemen Gorge, its preferable habitats are sparse riverside forests of Alnus glutinosa L. and Populus nigra L. neighboring grass communities. Larvae, adults and pupae were found up to 50 cm deep with most specimens inhabiting the upper soil layer from 0 to 20 cm deep. The highest recorded density was 89 adults and 581 larvae per 0.25 m2. Oviposition, hatching of the eggs, pupation and emergence of the new adults occur during the summer. Eggs have been found in surface soil layer in July and August, the pupae – mainly in July and August. Larvae of different instars were found in soil during all months of the study period. Adults from the new generation first occur in the beginning of August. In August, September and October adults from different generations can be found together. The main part of the adults seems to die after the reproduction period, and the common lifespan of adults seems to be about a year only. The life cycle of Ch. robustus in investigated habitat seems to be perennial and includes two years as larval stage and one as adult. Tropical Orphninae occupy a number of ecological niches but lack colonial geobiont specialists similar to Chaetonyx.