Stefano Chiari

Surveying an endangered saproxylic beetle, Osmoderma eremita, in Mediterranean woodlands: a comparison between different capture methods

Measuring population size is riddled with difficulties for wildlife biologists and managers, and in the case of rare species, it is sometimes practically impossible to estimate abundance, whereas estimation of occupancy is possible. Furthermore, obtaining reliable population size estimates is not straightforward, as different sampling techniques can give misleading results. A mark-recapture study of the endangered saproxylic beetle Osmoderma eremita was performed in central Italy by applying four independent capture methods within a study area where 116 hollow trees were randomly selected to set traps. Detection probability and population size estimates were drawn from each of these four capture methods. There were strong differences in detection probability among methods. Despite using pheromone and beetle manipulation, capture histories were not affected by trap-happiness or trap-shyness. Population size estimates varied considerably in both abundance and precision by capture method. A number of 0.5 and 0.2 adult beetles per tree was estimated using the whole data set by closed and open population models, respectively. Pitfall trap appeared the optimal method to detect the occurrence of this species. Since in the southern part of its distribution range, a single population of O. eremita is widespread in the landscape, and includes beetles from more than one hollow tree, conservation efforts should focus not only on preserving few and isolated monumental hollow trees, but should be extended to large stands.

Habitat of an endangered saproxylic beetle, Osmoderma eremita, in Mediterranean woodlands

Abstract: The habitat of Osmoderma eremita, a European endangered beetle species restricted to tree cavities, was examined in central Italy, at the southernmost limit of its distributional range. The occurrence of adults, larvae, and fragments was investigated in 170 and 151 living hollow trees by pitfall trapping and sampling of wood mould (i.e., loose material) in the hollow, respectively. Overall, O. eremita was present in 22% of the trees, which belonged to 4 different tree species (Ostrya carpinifolia, Quercus suber, Acer obtusatum, and Quercus pubescens). The frequency of presence was higher in cavities with more than 4 L of wood mould, in cavities with dry or half-moist wood mould rather than wet wood mould, and with wood mould with low soil contamination. A comparison with northern regions indicated that the warmer macro-climatic conditions in the south make the species independent of a warm microclimate. As most of the hollow trees contain only a small amount of wood mould (<4 L), the habitat quality is generally poorer than in oak pastures studied in northern Europe.

A European monitoring protocol for the stag beetle, a saproxylic flagship species

Developing protocols for threatened invertebrates is often challenging, because they are not only rare but also elusive. This is the case with the stag beetle (Lucanus cervus), a protected and flagship species for the saproxylic beetle fauna in Europe. We applied a standard transect walk at a European scale (8 countries, 29 transects) to test its practicability and reliability as survey design. A total of 533 sightings were recorded throughout the sampling period, but detection probability changed as the season progressed. Considering the observed activity pattern, occupancy models showed that a short period of three consecutive weeks, between the middle of June and the first week of July, resulted in a high probability of detection (P > 0.7). As time of the peak of activity varies from year to year and between sites, we propose to extend the sampling period to five weekly surveys. Detailed information on the transect characteristics and the optimal time for surveying were analysed. The data indicate that a weekly transect at dusk provides a reliable method for monitoring this species throughout its distributional range. No correlation was found between latitude, longitude and phenology of sightings, however. However, a standard method such as the one presented, allows broadening the scale of monitoring studies, provinding data to evaluate the efficacy of conservation measures.

Interactions between larvae of the threatened saproxylic beetle Osmoderma eremita and other flower chafers in Mediterranean woodlands: implications for conservation

Interactions between larvae of one of the most charismatic and threatened saproxylic beetles, Osmoderma eremita (Scopoli, 1763), and other flower chafer species (Coleoptera: Scarabaeidae) were investigated by taking samples of wood mould, i.e. loose material inside the cavity, from 151 living hollow trees in two Mediterranean woodlands during August 2010. Multi‐species occupancy models estimate low occupancy probabilities for both O. eremita (ψ ± SE = 0.36 ± 0.13) and other flower chafer species (0.42 ± 0.06), which showed similar microhabitat requirements without competing. In cavities where larvae of both groups were present, the probability of detecting O. eremita during the sieving of 2 l of wood mould was not affected by whether larvae of other flower chafers occur in the same sample and vice versa. Unexpectedly, larvae of O. eremita were detected with a higher probability when larvae of other flower chafers occurred in the cavity. Model selection statistics strongly support that increasing the sampled volume of wood mould increases the probability of detecting larvae, especially for O. eremita. Wood mould sampling resulted in a reliable method for detecting the presence of O. eremita larvae, but further studies are needed to investigate the potential damage caused by this procedure in the fragile microhabitat of tree cavities. To preserve populations of O. eremita and other flower chafers, management actions should be focused on increasing the density of hollow trees and the volume of tree cavities by favouring the natural ageing of trees and by creating artificial habitats in living trees.

Exaggerated Allometric Structures in Relation to Demographic and Ecological Parameters in Lucanus cervus (Coleoptera: Lucanidae)

Enlarged weapons and ornamental traits under sexual selection often show a positive allometric relationship with the overall body size. The present study explores the allometry of mandibles and their supporting structure, the head, in males of the European stag beetle, Lucanus cervus. This species shows a remarkable dimorphism in mandible shape and size that are used by males in intraspecific combats. Stag beetles were captured, measured, weighed, and released in the framework of a capture‐mark‐recapture study. The relationship of mandible length (ML) and head width in respect to the overall body size was described by a segmented regression model. A linear relationship was detected between ML and head width. The scaling relationships for both ML and head width identified the same switchpoint, highlighting the advantages of using combined results of weapons and their supporting structures in such analysis. These results led to a more consistent distinction of males in two morphologies: minor and major. The survival probability of individuals was dependent on the morphological class and was higher for minor males than for major. Elytron length and body mass of the individuals did not show any significant variation during the season. Differences in predatory pressure were detected between morphs by the collection and analysis of body fragments due to the predatory activity of corvids. Morphological differences and shift in demographic and ecological parameters between the two classes suggested that selection continues to favor intrasexual dimorphism in this species throughout a trade‐off mechanism between costs and benefits of carrying exaggerated traits. J. Morphol. 276:1193–1204, 2015.

Fauna Europaea: Coleoptera 2 (excl. series Elateriformia, Scarabaeiformia, Staphyliniformia and superfamily Curculionoidea)

Abstract Fauna Europaea provides a public web-service with an index of scientific names (including synonyms) of all living European land and freshwater animals, their geographical distribution at country level (up to the Urals, excluding the Caucasus region), and some additional information. The Fauna Europaea project covers about 230,000 taxonomic names, including 130,000 accepted species and 14,000 accepted subspecies, which is much more than the originally projected number of 100,000 species. This represents a huge effort by more than 400 contributing specialists throughout Europe and is a unique (standard) reference suitable for many users in science, government, industry, nature conservation and education. Coleoptera represent a huge assemblage of holometabolous insects, including as a whole more than 200 recognized families and some 400,000 described species worldwide. Basic information is summarized on their biology, ecology, economic relevance, and estimated number of undescribed species worldwide. Little less than 30,000 species are listed from Europe. The Coleoptera 2 section of the Fauna Europaea database (Archostemata, Myxophaga, Adephaga and Polyphaga excl. the series Elateriformia, Scarabaeiformia, Staphyliniformia and the superfamily Curculionoidea) encompasses 80 families (according to the previously accepted family-level systematic framework) and approximately 13,000 species. Tabulations included a complete list of the families dealt with, the number of species in each, the names of all involved specialists, and, when possible, an estimate of the gaps in terms of total number of species at an European level. A list of some recent useful references is appended. Most families included in the Coleoptera 2 Section have been updated in the most recent release of the Fauna Europaea index, or are ready to be updated as soon as the FaEu data management environment completes its migration from Zoological Museum Amsterdam to Berlin Museum für Naturkunde.

Antennal fine morphology of the threatened beetle Osmoderma eremita (Coleoptera: Scarabaeidae), revealed by scanning electron microscopy.

The aim of this study was to characterize the antennal morphology of Osmoderma eremita, a threatened scarab beetle inhabiting tree hollows. O. eremita males produce a sex pheromone, (R)‐(+)‐γ‐decalactone, responsible mainly for the attraction of females but also other males. Gross and fine morphology of microstructures including sensilla, microsculpture and pores were analyzed using Scanning Electron Microscopy. The antenna of O. eremita showed the typical lamellicorn shape of scarab beetles, with a basal scape, a pedicel, a funicle composed of five antennomeres and a club composed of three lamellae. Six different subtypes of sensilla chaetica (Ch.1 − 6), Böhm sensilla (Bo), one subtype of sensilla basiconica (Ba.1), two subtypes of sensilla coeloconica (Co.1 − 2), two subtypes of sensilla placodea (Pl.1 − 2), pores and peculiar folds were described. The two sexes did not show any significant differences in the occurrence and number of the sensilla placodea, known to be responsible for the pheromone reception. Instead, some sexual differences were found on the occurrence and topology of three different microstructures: (1) one subtype of sensillum chaeticum (Ch.2) occurring on the pedicel only in males; (2) a characteristic pore occurring on the funicle only in males; (3) a peculiar fold occurring on different antennomeres of the funicle in the two sexes, on the fourth in males and on the fifth in females. A comparison between sensilla of O. eremita and those of other Scarabaeoidea is provided. Microsc. Res. Tech. 79:178–191, 2016.

Scanning electron microscopy analysis of the antennal sensilla in the rare saproxylic beetle Elater ferrugineus (Coleoptera: Elateridae)

Abstract This work provides the first morphological analysis (both at gross and fine level) of the antennal structures in the genus Elater (Coleoptera, Elateridae). The typology, number and distribution patterns of the antennal sensilla in the rare saproxylic Elater ferrugineus (both male and female) were studied using scanning electron microscopy (SEM). The serrate antennae of E. ferrugineus consisted of a scape, a pedicel, and nine flattened flagellomeres. Overall, 10 types of sensilla were identified according to their morphological features: one type of sensilla chaetica (Ch), one type of Böhm sensilla (Bo), three types of sensilla trichodea (Tr.1–3), two types of sensilla basiconica (Ba.1–2), one type of sensilla styloconica (St), one type of grooved peg sensilla (Gp) and one type of sensilla campaniformia (Ca). A marked sexual dimorphism was found at both gross and fine scale. The male antenna was bigger (8.6 mm) than the female one (7.0 mm) and carried one type of sensilla trichodea (Tr.2) absent in female antennae possibly responsible for reception of the female-emitted sex pheromone. The female antenna carried a higher number of sensilla (~ 9800) than the male one did (~7,000), with more abundant sensilla chaetica (Ch) and basiconica (Ba.1 and Ba.2).