Using odour traps for population monitoring and dispersal analysis of the threatened saproxylic beetles Osmoderma eremita and Elater ferrugineus in central Italy

Pheromone-based monitoring could be a very efficient method to assess the conservation status of rare and elusive insect species, but there are still few studies for which pheromone traps have been used to obtain information on presence, abundance, phenology and movements of such insects. We performed a mark-recapture study of two threatened saproxylic beetles, Osmoderma eremita (Scarabaeidae) and its predator Elater ferrugineus (Elateridae), in two beech forests of central Italy using pheromone baited window traps and unbaited pitfall traps. Two lures were used: (1) the male-produced sex pheromone of O. eremita (racemic γ-decalactone) to attract females of both species, and (2) the female-produced sex pheromone of E. ferrugineus (7-methyloctyl (Z)-4-decenoate), to attract conspecific males. In total, 13 O. eremita and 1,247 E. ferrugineus individuals were trapped. For E. ferrugineus, males were detected earlier than females, and 7-methyloctyl (Z)-4-decenoate was much more efficient lure compared to racemic γ-decalactone in detecting its presence. The population size at the two sites were estimated to 520 and 1,369 individuals, respectively. Our model suggests a sampling effort of ten traps checked for 3 days being sufficient to detect the presence of E. ferrugineus at a given site. The distribution of dispersal distances for the predator was best described by the negative exponential function with 1 % of the individuals dispersing farther than 1,600 m from their natal site. In contrast to studies on these beetles in Northern Europe, the activity pattern of the two beetle species was not influenced by variation in temperature during the season.     

Influence of sampling effort on saproxylic beetle diversity assessment: implications for insect monitoring studies in European temperate forests

相似文献   

Demography and dispersal ability of a threatened saproxylic beetle: a mark-recapture study of the Rosalia Longicorn (Rosalia alpina)

The Rosalia longicorn or Alpine longhorn (Coleoptera: Cerambycidae) is an endangered and strictly protected icon of European saproxylic biodiversity. Despite its popularity, lack of information on its demography and mobility may compromise adoption of suitable conservation strategies. The beetle experienced marked retreat from NW part of its range; its single population survives N of the Alps and W of the Carpathians. The population inhabits several small patches of old beech forest on hill-tops of the Ralska Upland, Czech Republic. We performed mark-recapture study of the population and assessed its distribution pattern. Our results demonstrate the high mobility of the beetle, including dispersal between hills (up to 1.6 km). The system is thus interconnected; it contained ～2000 adult beetles in 2008. Estimated population densities were high, ranging between 42 and 84 adult beetles/hectare a year. The population survives at a former military-training ground despite long-term isolation and low cover of mature beech forest (～1%). Its survival could be attributed to lack of forestry activities between the 1950s and 1990s, slow succession preventing canopy closure and undergrowth expansion, and probably also to the distribution of habitat patches on conspicuous hill-tops. In order to increase chances of the population for long term survival, we propose to stop clear-cuts of old beech forests, increase semi-open beech woodlands in areas currently covered by conifer plantations and active habitat management at inhabited sites and their wider environs.     

Modelling geographic distribution and detecting conservation gaps in Italy for the threatened beetle Rosalia alpina

Presence-only models can aid conservation and management of threatened, elusive species. We developed a Maxent model for the rare cerambycid beetle Rosalia longicorn Rosalia alpina L. in Italy and neighbouring regions and identified the variables best explaining the species’ occurrence on a large scale. Once successfully validated, we used the model to (a) evaluate the current degree of fragmentation of R. alpina range in Italy; and (b) quantify the amount of the Italian territory with the highest probability of beetle presence within the existing national conservation areas (Natura 2000 network, parks and reserves). Low (<0.5) probability scores of R. alpina presence corresponded to 89% of the total area considered, whereas high scores (>0.9) covered only 2.5%. R. alpina was predicted to occur mostly in broadleaved deciduous forest at 1000–1700 m a.s.l. with warm maximum spring temperatures and May and November precipitation >80 mm. We found a high degree of fragmentation; gaps were mainly covered with farmland or other unsuitable habitat. Over 52% of potential habitat is unprotected. While the Natura 2000 network protects 42% of potential habitat, parks and reserve covers less than 29%. To preserve R. alpina, we urge to create, or restore, forest corridors to bridge the otherwise impermeable gaps our model detected and grant protection to the still largely unprotected area of the Italian territory e.g. by including it in further Natura 2000 sites. Models such as ours may also help focus field surveys in selected areas to save resources and increase survey success.     

Role of urban green spaces for saproxylic beetle conservation: a case study of tenebrionids in Rome,Italy

Forested urban areas provide many important ecosystem services and their preservation is considered of paramount importance. Although urban forest are known to host a high diversity of saproxylic beetles (i.e. those associated with dead wood), contributions dealing with the role of urban green spaces for their conservation are lacking. We investigated the importance of urban green spaces for saproxylic and non-saproxylic tenebrionid beetles in urban Rome. Based on species vulnerability scores we calculated two indices of area prioritisation, the Biodiversity Conservation Concern (BCC) and the Biodiversity Conservation Weight (BCW) for saproxylic and non-saproxylic species. Site area and forest surface correlated positively with saproxylic richness, whereas site isolation correlated negatively with non-saproxylic richness. BCC and BCW values for saproxylic species were positively correlated with distance from the city centre. For non-saproxylic species, BCW values were negatively correlated with distance from adjacent areas. These results suggest that saproxylic beetles require large areas covered by forest, but are not strongly influenced by isolation, which is important for non-saproxylic species. Non-saproxylic tenebrionids have limited dispersal capabilities, which explains their sensitivity to isolation, but are generally eurytopic species frequently found even in the city centre. By contrast, most saproxylic species are able to fly, but are mainly found in peripheral areas with large and relatively well preserved forest fragments. Maintaining and possibly enhancing connectivity among green spaces is important for the conservation of non-saproxylic species, whereas preserving large forest surfaces, especially in peripheral areas, is needed for the conservation of saproxylic species.     

Conflict between insect conservation and public safety: the case study of a saproxylic beetle (<Emphasis Type="Italic">Osmoderma eremita</Emphasis>) in urban parks

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.     

Hollow oaks and beetle conservation: the significance of the surroundings

In this study we investigated hollow oaks (Quercus robur, Q. petrea) situated in open landscapes and in forests in Norway in northern Europe, and compared their importance for rare and threatened beetles (Coleoptera). Old, hollow oak trees, both in parks and in forests, were extremely rich in red-listed beetles, and hosted a high proportion of threatened species. The proportion of oak associated species and the mean number of red-listed beetle species per tree was similar in the two site types, but rarefaction showed that for a certain number of individuals, oaks in forests had more threatened and near-threatened species than oaks in parks. The species composition also differed between site types: Park oaks had a higher proportion of species associated with hollows and animal nests, whereas in forests, there was a higher proportion of species depending on dead oak wood in general. Four factors were significant in explaining the richness of red-listed beetles in our study: Tree circumference, cavity decay stage, proportion of oak in the surroundings, and coarse woody debris (CWD) in the surroundings. Forest oaks were smaller, but they still trapped a species richness comparable to that of the larger park oaks—probably a result of high amounts of CWD in the surroundings. We show that oaks in open landscapes and oaks in forest have only partly overlapping beetle assemblages and, thus, cannot be substituted in conservation. Planning for conservation of red-listed beetles associated with this key habitat demands a large scale perspective, both in space and time, as the surroundings have important effects on associated threatened and near threatened species.     

Effects of trap baits and height on stag beetle and flower chafer monitoring: ecological and conservation implications

The implementation of conservation actions requires a reliable assessment of presence and/or abundance of targeted species. This is particularly difficult for rare and elusive species. In this study the use of bottle traps and the effects of two potential baits in relation to height in the trees were tested to detect presence and assess abundance of stag beetles (Lucanidae) and flower chafers (Scarabaeidae, Cetoniinae), an important component of forest biodiversity. The study was carried out in a flood-plain forest of northern Italy. Forty-eight handcrafted traps were assigned to two height categories (1.5–2 m and 10–20 m) and three kinds of bait: (i) red wine, white wine and sugar, (ii) red wine, beer and mashed banana, (iii) no bait, as control. Fieldwork lasted 8 weeks, with 32 surveys, from May to July. Overall, we recorded 399 captures of the following species: Dorcus parallelipipedus, Lucanus cervus, Cetonia aurata, Protaetia speciosissima, P.affinis, P. morio and P. cuprea. Traps baited with red wine, white wine and sugar showed the highest detection probabilities for all the species. A clear preference for the canopy layer (traps between 10 and 20 m high) was shown by all species except for D. parallelipipedus which was mostly captured between 1.5 and 2 m of height. The study period was long enough to improve ecological knowledge on species phenology, but not enough to include the whole phenology for all of them. The method allowed the assessment of population size only for flower chafers as the number of stag beetles captures was too low.     

Evolutionary ecology and the conservation of biodiversity

Studies on evolving interactions among species and the coevolutionary process have suggested that the conservation of biodiversity requires a broad geographic perspective, if the `interaction biodiversity' of the earth is to be conserved with its species diversity. Continued maintenance of the geographic mosaic of specialization, defense and population structure appears to be crucial to the coevolutionary process and the long-term persistence of some interspecific interactions.     

Phylogenetic position of a threatened stag beetle, Lucanus datunensis (Coleoptera: Lucanidae) in Taiwan and implications for conservation

Among nine endemic Lucanus beetles in Taiwan, L. datunensis is the island’s smallest and most threatened species. It currently exists as only one population located in tall grasslands of Mt. Datun in the Yangmingshan National Park. Given the isolated population, unique subtropical grassland, and the threats resulting from human activities, L. datunensis raises immediate conservation concern for its long-term survival. Phylogenies reconstructed from combined mitochondrial cytochrome oxidase subunit 1 (1310 bps) and nuclear wingless (436 bps) genes were resolved and placed L. datunensis as a phylogenetically distinct species sister to L. fortunei from China. All 13 examined individuals of L. datunensis shared just one mitochondrial haplotype suggesting extremely low mitochondrial DNA diversity and a small effective population size. L. datunensis and morphologically closest L. miwai were distantly related and appear to have evolved in parallel the life history traits of a small body size and diurnal mate-searching behavior. We hypothesize that these habitat-associated characters are convergent adaptations that have evolved in response to shifts from forests to grasslands.     

Movement and distribution of adult rusty grain beetle, Cryptolestes ferrugineus (Coleoptera: Laemophloeidae), in stored wheat in response to different temperature gradients and insect densities

The movement and distribution of adult Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae) in grain provide important information for detection of insect pests and for simulations of their distribution in grain bins. Adult movement and distribution were determined in 100 by 100 by 1000-mm wheat (14.5 +/- 0.2% moisture content) columns at four insect densities, three temperature gradients, and dynamic (changing) temperature conditions. Insect density was a minor factor influencing insect movement and distribution in grain columns with temperature gradients. Dispersal resulted in a uniform distribution at a higher insect density (higher than two adults per kilogram of wheat), and aggregation occurred at a low insect density. Adults wandered in the first 6 h after introduction, and there were fewer adults wandering in the vertical direction than in the horizontal direction. Adults moved faster in the vertical direction than in the horizontal direction, and the maximum speed of the movement was 6 m/d in the horizontal direction, and >10.8 m/d in the vertical direction through wheat. Adults could detect temperature gradients in <1 h and preferred warmer temperatures when they had a choice. Insect distribution in horizontal wheat columns at any temperature gradient was unstable for 24 h. Twenty-four hours after introduction, adults gradually overcame their positive geotactic behavior if the upper temperature was more biologically suitable or was not <27.5 degrees C. Adults responded faster to higher temperature gradients than to lower temperature gradients. There was a similar pattern of adult distribution in 144 h.     

Biology, ecology and conservation of the Mobulidae

The Mobulidae are zooplanktivorous elasmobranchs comprising two recognized species of manta rays (Manta spp.) and nine recognized species of devil rays (Mobula spp.). They are found circumglobally in tropical, subtropical and temperate coastal waters. Although mobulids have been recorded for over 400 years, critical knowledge gaps still compromise the ability to assess the status of these species. On the basis of a review of 263 publications, a comparative synthesis of the biology and ecology of mobulids was conducted to examine their evolution, taxonomy, distribution, population trends, movements and aggregation, reproduction, growth and longevity, feeding, natural mortality and direct and indirect anthropogenic threats. There has been a marked increase in the number of published studies on mobulids since c. 1990, particularly for the genus Manta, although the genus Mobula remains poorly understood. Mobulid species have many common biological characteristics although their ecologies appear to be species-specific, and sometimes region-specific. Movement studies suggest that mobulids are highly mobile and have the potential to rapidly travel large distances. Fishing pressure is the major threat to many mobulid populations, with current levels of exploitation in target fisheries unlikely to be sustainable. Advances in the fields of population genetics, acoustic and satellite tracking, and stable-isotope and fatty-acid analyses will provide new insights into the biology and ecology of these species. Future research should focus on the uncertain taxonomy of mobulid species, the degree of overlap between their large-scale movement and human activities such as fisheries and pollution, and the need for management of inter-jurisdictional fisheries in developing nations to ensure their long-term sustainability. Closer collaboration among researchers worldwide is necessary to ensure standardized sampling and modelling methodologies to underpin global population estimates and status.     

Characteristics and conservation priority of threatened plants in the Yangtze valley

One hundred and twenty-seven threatened species listed in the ChinaPlant Red Data Book were found in the Yangtze valley. One-third of them belongedto four families with high economic value, including Pinaceae, Magnoliaceae,Lauraceae and Ranuculaceae. Of all the plants, 66.9% grew in forests and 71.7%were threatened with damage to habitats. The threatened plants in the studiedregion formed a geographical pattern with two large and six small distributioncenters. The two large centers were in the high mountains in western Sichuan andnorthern Yunnan or around the Sichuan Basin. The six small centers were situatedin fragmented montane forests in the eastern part of the Yangtze valley. Todetermine a plant's threat category, the number of populations 10 wasused as the basic criterion as accorded with the China Plant Red Data Book. Thethreatened plants in the valley could be divided into five ranks of priority forconservation. The plants in the first rank comprised eight species endemic tothe valley, with only one population, which should be first preserved. It wasconcluded that human activity was the main factor threatening the survival ofplants, and protecting forests had been the most effective approach in savingthe threatened plants in the valley.