Deborah J. Harvey

Bionomics and distribution of the stag beetle, Lucanus cervus (L.) across Europe

Abstract.  1. The European stag beetle, Lucanus cervus, is thought to be widely distributed across its range, but a detailed description of its occurrence is lacking.

Development of non‐invasive monitoring methods for larvae and adults of the stag beetle, Lucanus cervus

Abstract.  1. The stag beetle, Lucanus cervus is Nationally Scarce in the UK, yet no methods exist for monitoring the abundance of adults or presence of the subterranean larvae.

Size variation and mating success in the stag beetle, Lucanus cervus

Abstract The stag beetle, Lucanus cervus, is Britain’s largest beetle, with a patchy distribution in southern England. The literature suggests that it displays exceptional size variation, particularly in the males, but no analysis of size inequality has ever been conducted. In the present study, stag beetle adults are measured and allometric relationships derived between various parameters and total body length. Most of the specimens found each year are fragments and head width can be used as a good predictor of total body length in each sex. Body size differs between years and between localities and male beetles show a greater degree of size inequality than females. However, L. cervus does not show greater inequality in size than many other beetle species and populations of males are composed of a relatively large number of small individuals. These males are not at a disadvantage in mating because it is the ratio of male : female size that determines mating success. Very large males are less successful in mating and it is suggested that lack of mating success may act as an additional constraint on mandible size in this species. Size variation is most likely caused by variation in larval food resources, coupled with variation in local climatic conditions.

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.

Testing the performance of a fragment of the COI gene to identify western Palaearctic stag beetle species (Coleoptera, Lucanidae).

Abstract The taxonomy of stag beetles (Coleoptera: Lucanidae) remains challenging, mainly due to the sexual dimorphism and the strong allometry in males. Such conjecture confounds taxonomic based conservation efforts that are urgently needed due to numerous threats to stag beetle biodiversity. Molecular tools could help solve the problem of identification of the different recognized taxa in the “Lucanus cervus complex” and in some related Palaearctic species. We investigated the potential use of a 670 bp region at the 3’ end of the mitochondrial cytochrome c oxidase subunit I gene (COI) for barcoding purposes (different from the standard COI barcoding region). Well resolved species and subspecies were L. tetraodon, L. cervusakbesianus, L. c. laticornis, as well as the two eastern Asian outgroup taxa L. formosanus and L. hermani. Conversely, certain taxa could not be distinguished from each other based on K2P-distances and tree topologies: L. c. fabiani / L. (P.) barbarossa, L. c. judaicus / an unknown Lucanus species, L. c. cervus / L. c. turcicus / L. c. pentaphyllus / L. (P.) macrophyllus / L. ibericus. The relative roles of phenotypic plasticity, recurrent hybridisation and incomplete lineage sorting underlying taxonomic and phylogenetic discordances are discussed.

Use of novel attraction compounds increases monitoring success of a rare beetle, Elater ferrugineus

The use of pheromones to determine distributions of rare saproxylic insects is an increasingly popular technique. Pheromones may, however, also be used to elucidate the biology of these cryptic species, a vital requirement if they are to be accurately monitored and conserved. We used non‐invasive aerial trapping to compare the effectiveness of chemicals produced by Elater ferrugineus L (Coleoptera: Elateridae), namely 7‐methyloctyl (Z)‐4‐decenoate (the female‐produced sex pheromone), and male compounds (geranyl and neryl acetone and 6‐methyl‐5‐heptene‐2‐one). The male compounds were identified using headspace analysis by solid phase micro‐extraction gas chromatography‐mass spectrometry. We discovered that males only produce these two compounds after having been attracted to a female, and that this serves to attract further males to a female. Such compounds do not appear to attract females but for a species that has a short activity period and is non‐feeding in the adult stage, may ensure breeding success when populations are low. By marking all beetles caught, we were able to demonstrate that recapture rate using this method is low (approximately 11% of total captures annually). Therefore, the method does not limit dispersal or breeding opportunities, making it a valuable tool for monitoring endangered saproxylic beetle species.

The stag beetle: a collaborative conservation study across Europe

Lucanus cervus L. (the stag beetle) is found across much of Europewhere, throughout its range, it is a species of restricted abundance and conservation interest. However, to date a great deal of the work undertaken on the insect has been carried out by individuals or groups working separately in each country (e.g. Harvey, 2007; Thomaes et al., 2008). At best, this approachmay lead to uncoordinated repetition of techniques, whilst at worst, it may fail to identify the needs of a species, if these differ across regions, resulting in population declines that cannot be reversed. Furthermore, as with many rare insect species, the European distribution of L. cervus is believed to be made up largely of metapopulations, i.e. discrete local populations connected by dispersal (Leisnham & Jamieson, 2002). In these, each of the local contributing populations will be different in terms of age, genetics, biotic and abiotic influences, meaning that each may face a different risk of extinction (Hanski, 1999). Therefore, as population persistence depends on the quantity, quality and connectivity of habitats, it is essential that the correct habitat structure is maintained in all areas where such species exist (Hanski, 1999). Increasing fragmentation of the landscape in urban areas, a major part of the habitat of L. cervus across parts of Europe, may lead to habitat density decreasing, with consequent reductions in dispersal rates, and a decline in the rate of establishment of new populations. For an insect that has a long life cycle (up to 6 years in the larval stage) and limited dispersal (Rink & Sinsch, 2006), habitat colonisation rates may commonly fall below a threshold necessary to sustain the metapopulation and extinctionwill follow (Hanski, 1999). Whilst L. cervus seems to exist in metapopulations, it is clear that those who monitor the species often do not. In this volume are presented the results of a collaborative conservation study of the species across Europe, with information shared across entomologists in a metapopulation-like fashion. The need for such an effort was identified by the fact that previous conservation strategies were determined on a countrywide basis, informed by research carried out within limited geographical areas. Often these were based on single reports of favoured habitats that may be unusual across the range of the species. Such an example is Tochtermann (1992) which reports that the favoured habitat of the insect is oak woodland. Whilst this appears to be true in some parts of the European range, in other areas the beetle seems commoner in urban environments, where oak is rare (Percy et al., 2000). Thus, for successful insect conservation, collaboration and information sharing amongst researchers is crucial, as it not only serves to establish protocols, but also, more importantly, highlights differences in the biology of a species across the whole of its range and prevents folklore from becoming ‘fact’. Trying to establish the life cycle and requirements of many saproxylic and subterranean organisms, includingL. cervus, presents problems since the protracted larval stage, followed by a short crepuscular adult phase, make research that is statistically and biologically significant difficult to achieve. In this issue, Harvey et al. (2011a) present a variety of novel, non-invasive methods for its detection and quantification, which should result in an improved knowledge of the species’ abundance. These techniques should be applicable to a wide range of subterranean and saproxylic species, whose larvae are invisible within a solid substrate. Successful conservation programmes must not just take into account prevailing circumstances, but also look to the future, when environmental and climatic conditions may be different. Predicted climate changes may have an enormous impact on the ecology and distribution of many organisms (Walther et al., 2002). Here, Rink and Sinsch (2011) outline the adverse effects of increasing temperature on L. cervus by considering life condition and activity period. This paper highlights the importance of considering abiotic influences on all stages of an insect’s development. Whilst the subterranean larvae may be buffered against temperature changes, it is clear that the adults are quite sensitive to abiotic effects. There are very few reports in the literature of collaborative initiatives covering the entire range of an endangered species, a notable exception being Ranius et al. (2005) who described the distribution and conservation strategies for another rare beetle, Osmoderma eremita. This multi-author paper is an excellent example of information sharing amongst laboratories leading to a comprehensive conservation plan. Here, Harvey et al. (2011b) present a similar analysis of the bionomics and distribution of L. cervus across 41 countries. Such projects allow the organism’s biology to be understood on a regional scale, thus enhancing the prospects of successful conservation. Biological differences revealed at these scales may lead to population genetics studies that can inform conservation strategies. It is hoped that the papers in this issue will stimulate other cross-country studies of insect conservation across large areas. Correspondence: Alan C. Gange, School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK. E-mail: a.gange@rhul.ac.uk Insect Conservation and Diversity (2011) 4, 2–3

Making the invisible visible: Determining an accurate national distribution of Elater ferrugineus in the United Kingdom using pheromones

To date, conservation‐status saproxylic beetle species in the UK have been monitored by chance findings or by monitor‐based observational studies. Here, using Elater ferrugineus as our target species, we present the first national distribution survey carried out in the UK or across mainland Europe on such a species using chemicals produced by the insect. Over 3 years, mark‐release‐recapture studies were performed across the UK, using 416 lured (pheromone) traps monitored by volunteer recorders; the first survey in Europe to do so. Traps were baited with 7‐methyloctyl‐ (Z)‐4‐decenoate, a compound previously identified as a female sex pheromone. The results were used to plot a distribution map and investigate factors that may influence the distribution, including summer temperatures, possible habitat availability and larval food source. The survey revealed a south‐eastern distribution of E. ferrugineus in the UK, which was suggested by previous casual studies. A correlative model was fitted to the data, indicating that 55% of the variation in the distribution of E. ferrugineus was explained by climatic variables (temperature and wind speed).