The European stag beetle, Lucanus cervus, is recognised as a flagship species for biodiversity conservation. Although the species is widely distributed across Europe declines have led to it being granted protected or endangered status in a number of countries and regarded as "near threatened" by the IUCN. The integration of genetic approaches into conservation efforts is urgently needed but has been impeded to date by the lack of appropriate genetic markers. To provide such a resource the development of the first microsatellite loci for stag beetle is described. Loci were identified using two methods (i) enriched library cloning (ELC) and (ii) Restriction enzyme Associated DNA sequencing (RAD-Seq). Inefficient microsatellite detection using the ELC method suggests that RAD-Seq, or other Next Generation Sequencing based methods, may ultimately be more cost effective for obtaining informative suites of markers for this and other coleopteran species. 18 loci were characterised by genotyping 42 UK specimens collected as prey leftover/roadkill. All loci produced unambiguous genotypes and were polymorphic. Though preliminary, estimates of genetic variability suggest UK populations may be genetically depauperate. The microsatellite loci represent a suite of genetic markers that can be applied to non-invasive population monitoring and numerous other areas of Lucanus conservation and evolutionary research., Niall J. McKeown, Deborah J. Harvey, Amy J. E. Healey, Ilze Skujina, Karen Cox, Alan C. Gange, Paul W. Shaw., and Obsahuje bibliografii
Males in many beetles show horn or mandible dimorphism. The stag beetle Dorcus rectus was assumed to have dimorphic males, but in this species there are not two but three visually distinct mandibular phenotypes. The aim of this study is to determine if the three phenotypes represent an allometric trimorphism in this species by studying the scaling relationship between body length and mandible length in 148 adult males and 31 adult females. The relationship was fitted using the following four statistical models; a simple line, a logistic curve, a continuous segmented line and a discontinuous line. The best-fitting model for the males was a discontinuous line with two break points and that for the females a simple line. The male data was also well fitted by a logistic curve. The discontinuous linear model divided the males into three groups that were in good agreement with the three phenotypes. These results suggest that a subtle allometric trimorphism possibly exists in males of this species. Small males of this species have no distinct teeth on their mandibles, whereas small males of D. striatipennis and D. curvidens, which are closely related to D. rectus, have a pair of distinct teeth on their mandibles. The phylogenetic relationship of these Dorcus species suggests that the trimorphism in D. rectus may have arisen through the loss of teeth in small males., Yutaka Iguchi., and Obsahuje seznam literatury
In insects, allometries of exaggerated traits such as horns or mandibles are often considered species specific and constant during a season. However, given that constraints imposed by the advancing season affect the developmental processes of organisms, these allometries may not be fixed, and the switch point between morphs may vary between populations and within populations during a season. The hypothesis of such a seasonal variation in exaggerated traits was tested using the dimorphic males of the beetle Lucanus cervus. The remains of specimens killed by predators were collected along forest tracks from mid May to late August 2008 in a protected lowland forest in northern Italy. The largest beetles were collected in mid May and average size thereafter decreased. Males collected early in the season mostly had large mandibles (i.e. they belonged to the major morph). In contrast, late in the season the probability of finding males with large mandibles was very low. The threshold body size determining morph expression also shifted during the season. Early in the season, the threshold pronotum width for a 50% chance of developing into the major morph was 1.74 cm, whereas later in the season it was 1.90 cm. This shift in the threshold body size was interpreted as the effect of phenotypic plasticity in a population exposed to constraints imposed by the advancing season. and Sönke Hardersen, Anna L.M. Macagno, Roberto Sacchi, Ilaria Toni.
The benefits for offspring of attendant adult were investigated in the stag beetle Figulus binodulus. The initial growth rate of third-instar larva was significantly higher when the larvae were in a nest with adults compared to those in a nest without adults. The difference in growth rate is reflected in adult body size. Although the presence of adult beetle generally benefited the offspring, the adults did eat some of the larvae. Filial cannibalism was the primary cause of juvenile death in nests with adults. Mortality was lower in nests with adults related to the juveniles compared to nests with unrelated adults, suggesting that infanticide of nest mates may be inhibited. These results suggest that F. binodulus has a level of sociality and nest mate recognition that is very rare in stag beetles. Social behaviour may be more advantageous for small stag beetles than fighting.
The genus Aesalus F., 1801 of the family Lucanidae in the Himalayas is reviewed, and a new species, A. saburoi sp. n., is described from Central Nepal. This new species has been confused with A. himalayicus Kurosawa 1985, but differs from the latter mainly by a darker and broader body, and by different shapes of the intercoxal process of the prosternum and of male genitalia. The male of A. himalayicus sensu stricto is described for the first time and the male genitalia are illustrated. A key to the members of the genus Aesalus from the Himalayas is provided.
Larvae of the stag beetle, Dorcus rectus, feed on decaying wood, which they digest with the aid of symbiotic yeasts; however, they can be successfully reared on artificial diets containing only fungal tissue. In this study we tested whether D. rectus larvae can utilize fungal cell walls, which are an insoluble component of mycelium. Lyophilized Bjerkandera adusta mycelium cultured in potato-dextrose liquid medium consisted of a 47.6% hot-water insoluble fraction by mass, which contains 53.7% of the total nitrogen in the mycelium. D. rectus larvae that hatched from surface-sterilized eggs were reared for 14 days on agar-based diets containing either the soluble fraction, insoluble fraction or both, extracted from 100 mg of mycelium. The larvae increased in mass most on the mixed diet, and there was no difference in their growth on the mixed and positive control diets. Both the soluble and insoluble fractions improved larval growth compared to the negative control diet; however, the growth rates were much lower than those expected from the nitrogen dose-growth response curve obtained in a previous study. Addition of b-chitin to the soluble fraction did not positively affect larval growth. Therefore, we conclude that (1) D. rectus larvae need both the soluble and insoluble fractions of mycelium and (2) the larvae digest the insoluble fraction using their own enzymes., Masahiko Tanahashi, Kôhei Kubota., and Seznam literatury